Top 10 Questions for Inby (Roof Bolter) Interview

Feeling lost in a sea of interview questions? Landed that dream interview for Inby (Roof Bolter) but worried you might not have the answers? You’re not alone! This blog is your guide for interview success. We’ll break down the most common Inby (Roof Bolter) interview questions, providing insightful answers and tips to leave a lasting impression. Plus, we’ll delve into the key responsibilities of this exciting role, so you can walk into your interview feeling confident and prepared.

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Essential Interview Questions For Inby (Roof Bolter)

1. What is the purpose of roof bolting?

Roof bolting is a technique used in underground mining to support the roof of a mine, preventing it from collapsing.

2. What are the different types of roof bolts?

Types of Roof Bolts

• Cable bolts
• Fully grouted bolts
• Mechanical anchor bolts
• Split set bolts

3. What are the key considerations when choosing a roof bolt?

When choosing a roof bolt, it is important to consider the following factors:

• Ground conditions
• Depth of the bolt
• Diameter of the bolt
• Type of resin or anchor

4. What is the proper procedure for installing a roof bolt?

The proper procedure for installing a roof bolt is as follows:

• Drill a hole in the roof of the mine
• Insert the roof bolt into the hole
• Tighten the bolt until it is fully seated
• Apply a torque wrench to the bolt to ensure it is properly tightened

5. What are the safety precautions that must be taken when working with roof bolts?

When working with roof bolts, it is important to take the following safety precautions:

• Wear a hard hat
• Wear safety glasses
• Wear gloves
• Use a torque wrench to ensure the bolts are properly tightened
• Never work under a roof that is not properly supported

6. What are the common problems that can occur with roof bolts?

Some common problems that can occur with roof bolts include:

• The bolts can loosen over time
• The bolts can be damaged by falling rocks
• The bolts can be corroded by water

7. What are the maintenance procedures that should be performed on roof bolts?

Roof bolts should be inspected regularly for signs of damage or corrosion. The bolts should also be tightened periodically to ensure they are properly seated.

8. What are the different types of roof bolting machines?

Types of Roof Bolting Machines

• Manual roof bolting machines
• Semi-automatic roof bolting machines
• Fully automatic roof bolting machines

9. What are the advantages of using a roof bolting machine?

Roof bolting machines offer a number of advantages over manual bolting:

• They are faster and more efficient
• They are more accurate
• They are safer

10. What is the future of roof bolting?

The future of roof bolting is likely to see the development of new and innovative bolt designs and installation methods.

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Key Job Responsibilities

An Inby (Roof Bolter) is responsible for maintaining and securing underground mine workings by installing roof bolts and other support systems. Their key job responsibilities include:

1. Drilling and Bolting

Operate a roof bolting machine to drill holes and install roof bolts in underground mines.

• Determine the appropriate bolt pattern and hole depth based on geological conditions.
• Drill holes at precise angles and depths, and insert bolts with proper torque and tension.

2. Ground Support Installation

Install various ground support systems to reinforce mine workings and prevent roof collapses.

• Set up and operate hydraulic props, cable bolts, and other support systems.
• Ensure that support systems are properly anchored and tightened according to specifications.

3. Safety and Maintenance

Uphold safety standards and maintain equipment in optimal condition.

• Comply with safety regulations and wear appropriate protective gear.
• Inspect and maintain roof bolting machines and other equipment regularly.

4. Monitoring and Inspection

Monitor ground conditions and inspect installed support systems for any signs of deterioration or failure.

• Report any unsafe or unstable conditions to supervisors.
• Conduct regular inspections of roof bolts, cable bolts, and other support systems.

Interview Prepration Tips

To ace an interview for an Inby (Roof Bolter) position, it’s crucial to prepare thoroughly and showcase your skills and experience. Here are some helpful tips:

1. Research the Company and Role

Learn about the mining company, its operations, and the specific responsibilities of the Inby role. This knowledge will help you tailor your answers to the interviewer’s questions.

• Visit the company’s website and read about its history, values, and current projects.
• Study the job description carefully and identify the key skills and qualifications required.

2. Practice Common Interview Questions

Prepare for common interview questions by practicing your answers. This will boost your confidence and help you articulate your experience and strengths effectively.

• Prepare answers to questions about your drilling and bolting experience, ground support installation skills, and safety practices.
• Practice STAR (Situation, Task, Action, Result) method to provide specific examples of your accomplishments.

3. Highlight Your Safety Mindset

In underground mining, safety is paramount. Emphasize your commitment to following safety regulations and maintaining a safe work environment.

• Describe your understanding of safety protocols and how you apply them in your work.
• Provide examples of your proactive approach to identifying and mitigating potential hazards.

4. Demonstrate Your Physical Endurance

The job of an Inby requires physical endurance. Prepare to discuss your physical capabilities and how you maintain them.

• Explain your experience working in confined spaces and operating heavy machinery.
• Share any certifications or training you have received in physical fitness or endurance.

Next Step:

Armed with this knowledge, you’re now well-equipped to tackle the Inby (Roof Bolter) interview with confidence. Remember, preparation is key. So, start crafting your resume, highlighting your relevant skills and experiences. Don’t be afraid to tailor your application to each specific job posting. With the right approach and a bit of practice, you’ll be well on your way to landing your dream job. Build your resume now from scratch or optimize your existing resume with ResumeGemini. Wish you luck in your career journey!

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• 1. 1. (a)Define the nature of underground mining system? -1 (b)Discus the criteria of selecting mining method? -2 (c)What is caving system? -3 (d)Briefly discus about hoisting and it's types. -4 (e)Classify the ore deposit mineral system. -5 Answer to the question no : 1 a) The nature of underground mining system: 1. The most critical factors are ore & rock strength. 2. The presence of groundwater & the rock temperature gradient in the locality. 3. The social, economic, political & environment factors in underground mining are often quite different from surface mining b) The criteria of selecting mining method: The following are (1) Spatial characteristics of the deposit: *Size *Shape *Attitude *Depth (2) Geologic and hydrologic conditions: * Mineralogy *Chemical composition *Deposit structure (3) Geotechnical properties: *Elastic properties *Plastic behavior * State of stress *Rock mass rating (4) Economic considerations: *Reserves *Production rate *Mine life
• 2. *productivity *Comparative mining and capital costs (5)Technological factors: *Recovery *Dilution *Flexibility of the method *Selectivity of the method (6)Environmental concerns: *Ground control to maintain integrity of opening *Subsidence or coving effect at the surface *Atmospheric control *Workforce *Comparative safety *Availability of suitable waste c) Caving system: We define caving methods as those associated with induced, controlled, massive caving of the ore body, the overlying rock, or both, concurrent with and essential to the conduct of mining. There are three current methods that are considered to be caving methods. 1. Longwall mining 2. Sublevel mining 3. Block caving d) Hoisting system It is with the hoisting system itself those components of the hoist plant located in then hoist room- that engineering design is mainly needed. Three key factors govern hoist selection : 1. Production rate or tonnage to be hoisted per unit of time 2. Depth of shaft 3. Number of levels to be accessed There are only two hoist types commonly used today: Drum and friction a drum hoist stores the rope not extended in the shaft on the face of the drum. A friction hoist passes the rope over the top of the drive wheel but does not store it. Here the types of hoisting
• 3. 1. Single – drum, Unbalanced hoist: a single drum is the simplest type, with on rope and on conveyance 2. Single- drum, counterweighted hoist : when configured with two ropes, winding in opposite direction so that on conveyance ascends while the other descends, the conveyances balance each other and the power requirements decrease significantly 3. Double- drum hoist: The disadvantages of a single drum over under hoist are eliminated with a double drum configuration 4. Blair multi rope hoist: while traditional drum hoist can lift loads from very deep depths, the limitations is that is conveyance is held by only one rope. 5. Friction hoists: friction or koepe hoist make use of the fact that loads in balanced often generate sufficient rope pressure on the sheave to be driven by friction. 6. Performance characteristics: with their different principles, shapes and numbers and arrangements of ropes, the various hoisting systems exhibit quite different performance characteristics. e) Classification of ore deposit mining system: class Class description group Group description 11 Open stope system 1 Under hand system 2 Over hand system 3 Longwall systems 4 Room and pillar systems 5 Sublevel stopping systems 6 Room and level system 2 Shrinkage systems 1 System with blasting from shrinkage system 2 System with breaking from special workings 3 System with breaking by deep holes 3 Supported stope systems 1 System with reinforced stolls & square set 2 System with stope composite support 4 Cut & fill systems 1 Horizontal slicing systems with filling 2 Inclined slicing system with filling 3 Overhand system with filling 4 Long wall system with filling 5 Descending slicing system with filling 6 Systems with support & filling 5 Rock caving systems 1 Slicing & caving systems 2 Shield systems 3 Pillar system with roof caving 6 Ore & rock caving systems 1 Sublevel caving systems 2 Self level-shelf caving system 3 Level forced caving systems 7 combined system 1 Combined room open stope systems 2 Combined room shrinkage systems 3 Combined room stopping & filling systems
• 4. 2. (a) What is crop caol? -1 (b) Classify supported mining method. -2 (c) Explain ramp with proper sketch. -3 (d) Define shrinkage system and classify the system. -4 (e) Draw and describe the multi-level acess design. 5 Answer to the question no : 2 a) Coal of inferior quality near the surface. The coal next to the roof in a seam. b) Supported underground mining methods:  Cut and fill stoping  Stull stoping  Square set stoping c) Ramp is a sloping surface joining two different levels, as at the entrance or between floors of a building. Spiral ramps: Spiral ramps allow vehicles to travel at moderate speeds without having to slow to round corners, as in the case of switchback ramps, and can access multiple levels reasonably well with short cross-cuts. They also provide a compact footprint when land parcel size on surface is a design constraint. They can however be harder on equipment and operators who must be subjected to continuous centripetal forces. Switchback ramps: Switchback ramps are ideal for accessing all levels and sublevels with minimal cross-cuts and should therefore be the primary choice for ore handling and service ramps, particularly when
• 5. low development costs are a priority. They do however require vehicles to slow at each corner, which can substantially increase travel/ cycle times. Straight ramps: Straight ramps are rarely capable of accessing all the necessary levels of a mine and should therefore be reserved for surface production ramps. They allow vehicles to travel faster than other ramp types. Straight ramps will reach surface a substantial distance from the orebody and infrastructure placement should be planned accordingly. Consequently, larger land ownership requirements are also required. It should however be noted that in some cases these problems can be solved with a single well placed switchback. d) Shrinkage system: It is called vertical stoping method in which the ore is mined in horizontal slices from bottom to top and remains in the stope as temporary support to the walls and to provide a vertical platform for the miners. Stope width 3 to 100ft (1-30m), length 150 t 300ft (45-90m) and height from 200 to 300ft (60-90m). Classification of shrinkage stoping system: (i) Systems with blasting from shrinkage system (ii) Systems with breaking from special workings (iii) Systems with breaking by deep holes e) Drift: Drift is a more general mining term, meaning a near-horizontal passageway in a mine, following the bed (of coal, for instance) or vein of ore. A drift may or may not intersect the ground surface. A drift follows the vein, as distinguished from a crosscut that intersects it, or a level or gallery, which may do either. All horizontal or subhorizontal development openings made in a mine have the generic name of drift. These are simply tunnels made in the rock, with a size and shape depending on their use—for example, haulage, ventilation, or exploration. Fig: Drifting Ramp: A sloping surface joining two different levels, as at the entrance or between floors of a building.
• 6. Fig: Ramp Conveyor belt: A conveyor belt is the carrying medium of a belt conveyor system. A belt conveyor system is one of many types of conveyor systems. A belt conveyor system consists of two or more pulleys with an endless loop of carrying medium—the conveyor belt—that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The powered pulley is called the drive pulley while the unpowered pulley is called the idler pulley. There are two main industrial classes of belt conveyors; Those in general material handling such as those moving boxes along inside a factory and bulk material handling such as those used to transport large volumes of resources and agricultural materials, such as grain, salt, coal, ore, sand, overburden and more. Fig: Conveyor belt 3. (a)Define underground mining system. -1 (b) What is the function of underground mine pumping?? -2 (c)Illustrate an adit. -3 (d)Explain the cycle of operations of stope and pillar mines. -4 (e)Briefly describe the types of haulage system in underground mining. -5
• 7. Answer to the question no: 3 a) Minerals or ore deposits are exploited from beneath the earth surface which technics are applied is called underground mining system. Underground mining systems are applied below the depth about >300m. b) Function of underground mine pumping-  Cooling the underground area  Discharge the contaminated water  Protect the mine from underground water  Protect the sump from over loaded of water  Maintain the pure water supply c) Main horizontal or near horizontal underground opening with single access to the surface for working or developing of mine. d) The stope and pillar method is the most widely used of all underground hard rock mining procedures. Stope and pillar mining is the unsupported method in which openings are driven horizontally regular or random pattern to from pillars for ground support. Nearly all stope and pillar mines use conventional mining practice, with the production cycle involving: Production cycle = drill + blast + load + haul
• 8. The cycle of operations consists of the following: Drilling: Hydraulic or pneumatic drill jumbos are heavily favored; rotary drill rigs can be used in softer rocks. Blasting: Ammonium nitrate and fuel oil, gels,or emulsions; charging by hand or by pneumatic loader; firing by electric, nonelectric, or detonating fuse. Secondary blasting: Drill and blast; impact hammer; drop ball. Loading: A load-haul-dump device and front-end loader are very common; shovel, overhead mucker, and slusher occasionally used. Haulage: Truck, LHD, belt conveyor, shuttle car. e) In underground mining haulage is a horizontal transport system. Bulk materials in mining are transported by haulage system.  This can be described under two headings – track and trackless.  Track haulage includes rope and locomotive haulage, which runs on rail or track.  Trackless systems includes automobile (e.g. trucks), conveyors and transportation through pipes. In underground mines rails, trucks, shuttle cars, LHDS and conveyors are widely used. Haulage also perform in working zones are as follows-  Loading  Travelling loaded  Dumping  Traveling empty 4. (a)What is ramp -1 (b)Difference between haulage & hoisting in an underground mining. -2 (c)Discuss about the classification of underground mining. -3 (d)Illustrate the mining methods which are used in Boropukuria. -4 (e)Define shaft? Classify the shaft according to their activities & structure. Describe about the Shafts which are available in maddhapara. -5 Answer to the question no: 4 5. (a)What is blasting agent? -1 (b)Difference between rock caving system & ore and caving system. -2 (c)Which mining method is applied in Maddhapara hard rock mine and also describe. -3
• 9. (d)Explain the typical variations of room and pillar mining. -4 (e)Briefly discuss about open stope systems and It's types. -5 Answer to the question no: 5 a) Blasting agent – Any material consisting of a mixture of a fuel and an oxidizer. Example: Ammonium Nitrate and fuel oil. b) Differences between rock caving system and ore & rock caving system – Rock caving systems are the 5th class of underground mining which have low labor productivity. On the other hand ore & rock caving systems are the 6th class of same mining system but the systems are highly productive. c) Room and pillar mining method is applied in Maddhapara hard rock mine. Room and pillar mining – Room and pillar mining system is the 4th group of open stope systems. It is consider as an unsupported method. It is very old method applied to horizontal or near horizontal deposits that have been adopted is refined over the years. These systems are used for horizontal and flat dipping ore bodies 2 to 30m thick with stable ore and overlying rock. Cycle of operation: Production cycle = Cutting + Drilling + Blasting + Loading + Hauling  Cutting: Cutting machine is used for coal mining. For noncoal mining cutting isn’t used.  Drilling: Hydraulic and pneumatic drill jumbo’s ore heavily favored rotary drill rigs can be used in softer rocks.  Blasting: Ammonium nitrate and fuel oil (ANFO) gels or emulsion charging by pneumatic loader, firing by electric, nonelectric or detonating fuse.  Loading: A laud-haul-dump device and front end loader are very common, shovel, slushier are used.  Hauling: Truck, LHD, belt conveyer, shuttle car used. d) Advantages, disadvantages and applications of room and pillar mining: Advantages: 1) Moderate high productivity. 2) Moderate mining cost. 3) Moderately high production rate. 4) Good recovery. 5) Low to moderate dilution (0 to 40%). 6) Suitable to mechanizations. Disadvantages: 1) Caving and subsidence occur with pillar recovery.
• 10. 2) Poor recovery (40 to 60%) without pillar extraction. 3) Ground strength stress and support loads increase with depth. 4) Potential health and safety hazards. Applications: Room and pillar dominantly used in coal mining but finds some use in many other commodities. e) There are three typical variations of room and pillar mining such as i. Classic room and pillar mining. ii. Post room and pillar mining. iii. Step room and pillar mining. Classic room and pillar mining: Applies to flat deposits having moderate to thick beds and to inclined deposits with thicker beds. Mining the ore body creates large open stopes where trackless machines can travel on the flat floor. Ore bodies with large vertical heights are mined in horizontal slices starting at the top and benching down in steps. Fig: Classic room and pillar mining Post room and pillar mining: Applies to inclined ore bodies with dip angles from 20° to 50°. These mines have large vertical heights where the mined out space is backfilled. The fill keeps the rock mass stable and serves as a work platform while the next ore slice is mined.
• 11. Fig: Post room and pillar mining Step room and pillar mining: It is an adaptation of trackless mining to ore bodies where dip is too for rubber tired vehicles. A special “angle” orientation of haulage drifts and stopes related to dip creates work areas with level floors. This allows trackless equipment to be used in drilling and mucking. Mining advances downward along the step room angle. Fig: Step room and pillar mining 6. (a) What is backfill? -1 (b) Define about shaft sinking?? -2 (c) Expline the working principle of axial flow fan?? -3
• 12. (d) Discuss the differences between supported and unsupported mine?? -4 (e) Briefly describe the Room and pillar method for Barapokuria coal mining?? -5 Answer to the question no: 6 a) Mine waste or rock used to support the roof after coal removal. b) Shaft sinking define as the excavation a vertical or near the vertical tunnel from the top down where there is initially no access to the bottom. When the top of the excavation is the ground surface, it is referred to as shaft sinking when the top of the excavation is underground it is called a sub shaft. c) Axial flow fans are categorized as turbo machines. They have an impeller which is made up of a hub which carry the blades. The impeller is attached to a shaft which is rotated by an electric motor in most common applications. Before and after the blade row it is good practice to install guide vanes or straightened vanes, to reduce swirl and turbulence. The diffuser forms part of the casing that helps in recovering velocity pressure..  An axial fan with improvised efficiency, by using an industrial example for demonstration purpose and establish a systematically design procedure which predicts the fan performance where usage of computational fluid dynamics (CFD) will be instrumental.  High volume flow and low pressure fans are used in cooling applications for several process equipment and also for ventilation of silo cones, mines etc.  Present paper focuses on a specific application, related to clinker kiln-shell cooling.  Present work deals with axial flow fan of type power absorbing turbomachines.  The flow in the investigated form, i.e., air, is characterized by Mach numbers below the compressibility limit (< 0.3).  It is a clear case that fan operating with incompressible flow, which is a type of high capacity, low head (pressure), and single stage axial flow type turbomachine. Fans are a kind of equipment where we can use engineering strategies and optimize the energy consumption without effecting their efficiency. An axial flow fan can achieve high efficiencies as with an optimum blade settings and is only slightly lower than that obtained with the backward inclined aerofoil centrifugal fan and much better than convectional fans d) Unsupported Methods.
• 13.  The unsupported methods of mining are used to extract mineral deposits that are roughly tabular (plus flat or steeply dipping) and are generally associated with strong ore and surrounding rock.  These methods are termed unsupported because they do not use any artificial pillars to assist in the support of the openings  However, generous amounts of roof bolting and localized support measures are often used.  Room and pillar mining is the most common unsupported method, used primarily for flat-lying seams or bedded deposits like coal,trona, limestone, and salt Supported mining methods  Supported mining methods are often used in mines with weak rock structure. Cut-and-fill stopping is the most common of these methods and is used primarily in steeply dipping metal deposits.  The cut-and-fill method is practiced both in the overhand (upward) and in the underhand (downward) directions.  As each horizontal slice is taken, the voids are filled with a variety of fill types to support the walls.  The fill can be rock waste, tailings, cemented tailings, or other suitable materials. Cut- and-fill mining is one of the more popular methods used for vein deposits and has recently grown in use. . e) The underground mining is the only potential way for the utilization of the lignite reserves from an open pit exploitation which could remain unexploited due to high stripping ratios.  It is the most common supported pillar method, designed and used primarily for mining flat-lying seams ,or tabular ore bodies, or gently dipping bedded ore deposits of limited thickness (like coal, oil shale ,limestone ,phosphate ,salt ,trona ,potas )  Room and pillar method are well adapted to mechanically use and it applied on the sedimentary rock such as shale’s limestone coal seams phosphate layers.  Pillars are left in place in a regular pattern while the roof support.  Support of roof is provided by natural pillars in systematic way.  Mining cavity is supported by the strength of the roof support.  Room and pillar mining has a low recovery rate. In many room and pillars generally the pillars take out in a starting stop access allowing the roof t to collapse and fill in the stop.
• 14.  It is an advantageous mining method for shallow ore bodies as a mine of preventing surface subsidence. His tonic ultra-shallow ore bodies underground coal mining g (<30 m) never the are characterized by subsidence in the areas between the pillars.  Pillars are sometimes mined on retreat from a working area in cluing closer and caving of these working panels and raising the risk of surface subsidence. Fig :Room and pillar mining 7. (a) What is Adit? - 1 (b) Write down the advantages and disadvantages of stope and pillar Mining. – 2 (c)How many types of underground mining are there? Explain with proper Illustration.-3 (d) Which conditions are considered in cut and fill mining method. - 4 (e)Draw layout of main access opening for an underground coal mine. – 5 Answer to the question no: 7 a) A nearly horizantal passage from the surface by which a mine is entered and dewatered. b) Given below the conditions which are considered in cut and fill mining method. 1. Ore strength 2. Rock strength 3. Deposit shape 4. Deposit dip 5. Deposit size 6. Ore grade 7. Ore uniformity 8. Depth
• 15. c) Drawing below the layout of main access opening for an underground coal mine. Fig: Main access opening for an underground coal mine. d) Mainly there are three types of underground mining method. These are- 1. Supported method 2. Unsupported method 3. Caving method 1. Supported method: Three methods are in this class- I. Cut and fill stoping II. Stull stoping III. Square set stoping 2. Unsupported method: The following methods are in this class- I. Room and pillar mining II. Stope and pillar mining III. Shrinkage stoping IV. Sublevel stoping 3. Caving method: There are three current method that are considered to be caving methods- I. Longwall mining II. Sublevel caving III. Block caving e) Stope and pillar mining: It is the unsupported method in which openings are driven horizontally in regular or random pattern to form pillars for ground support. The advantage and disadvantage of this method are given below- Advantage:-
• 16. i. Moderate to high productivity ii. Moderate mining cost iii. Moderate to high production rate iv. Fair to good recovary Disadvantage:- i. Ground control requires continous maintenance ii. Difficult to provide good ventilation iii. Some ore loss in pillars iv. Recovary of pillars difficult or impossible 8. (a)Define Grizzly. -1 (b)What are the condition of Room and pillar mining method? -2 (c)Difference between fracture and Fisher? -3 (d)Why artificial ground freezing is required for Shaft construction? Explain briefly -4 (e)Sketch and explain block development for sublevel stopping with self-propelled Machinery. -5 Answer to the question no: 8 a) Grizzly: Arrangement that prevents oversized rock from entering an ore transfer system. A grizzly usually consists of a steel grating for coarse screening. b) The conditions of room and pillar mining are- *Room and pillar mining is designed for flat- bedded deposit. *This method is used to recover resources in open stopes. *The deposit should be in tabular form. * The thickness of the deposit must be greater than 30cm. c) Difference between fracture and fissure – A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will sometimes form a deep fissure or crevice in the rock. Fractures are commonly caused by stress exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. Fractures can provide permeability for fluid movement, such as water or hydrocarbons. Highly fractured rocks can make good aquifers or hydrocarbon reservoirs, since they may possess both significant permeability and fracture porosity.
• 17. Where fissure is a deep and narrow depression cutting across the reef front with origins relating to jointing planes in the reef limestone or non-limestone bedrock. Fissure is an extensive crack, break, or fracture in the rocks. d) The reason why artificial ground freezing method is required - Ground freezing in construction. Artificial ground freezing is a construction technique that is used in the construction of shafts, mines and tunnels to provide temporary earth support and groundwater control when other conventional methods such as dewatering, shoring and grouting or soil mixing do are not feasible. Ground freezing for deep shaft excavation. Deep shafts are the most common application of ground freezing. The freeze pipes are drilled and installed around the perimeter of the proposed shaft do the required depth. The circulation of the coolant is initiated until a frozen zone ranging from 1 to ten meters is formed. Ground freezing is mostly used for temporary ground support or structural element respectively and as a ground water control system. The advantage of frozen ground is that frozen water is 100% impermeable. Even obstacles like stones, concrete remnants or similar materials, which usually cause problems as a barrier when grouting techniques are used for sealing tasks, will just be embedded in the frozen soil volume as the frost grows through and around all obstacles. Ground freezing is being used in underground construction projects for the following listed applications:  Sinking and lining of deep mineshafts up to depth of more than 600 m  Deep excavations (shafts) – tunneling using the sequential excavation method SEM under the protection of a structural and watertight frozen soil body  Cross-passages between shafts and tunnel tubes or between tunnel tubes, respectively  Large open excavations, retaining walls  Temporary soil improvement under foundations  Temporary sealing of leakages e) In parallel development several development workings are driven simultaneously at several levels. This method has several advantages-lower cost of shrinking the main shaft to several levels simultaneously.
• 18. The stopping technique is vital for selecting the arrangement of haulage working and block raises. Fig: Block development for sublevel stopping with self-propelled machinery The figure illustrates a variant of block development for sublevel stopping with self-propelled machinery. The main haulage drift 1 and auxiliary drift is connected by the ventilation raise 3 to sublevel drifts 4 and ventilation drift 5 of the upper horizon. The OE from the sublevel is fed via permanent ore passes 6 and loading chambers 7 to the main haulage drift. The spiral entry 8 serves to move the self-propelled machinery between the horizons. 9. (a)Define dilute? -1 (b)How many types of underground openings. -2 (c)Discuss about the ventilation system of underground mine. -3 (d)Briefly discuss about unsupported Method in underground mining. -4 (e)Illustrate Room and Pillar mining method. And describe why it is suitable for Maddhapara Hard rock mine? -5 Answer to the question no: 9 10. (a) What is sump? -1 (b)Define raise and drift.-2 (c)Sketch the opening by vertical shaft.-3
• 19. (d)Describe feasibity analysis of mining.-4 (e)Write down the main opening schemes for ore deposits.-5 Answer to the question no: 10 a) Sump – The bottom of a shaft , or any other place in a mine , that is used as a collecting point for drainage water . b) Raise-  a secondary or tertiary inclined or vertical opening  driven upward from a level to connect with the level above  to explore the ground for a limited distance above one level. Drift-  a near-horizontal passageway in a mine  following the bed or vein of ore  it is distinguished from a crosscut. c) The opening method by vertical shaft are as follows- 1. Opening by vertical shafts sunk in the footwall (fig:1). 2. Opening by vertical shafts sunk in the hanging –wall (fig: 2) 3. Opening by vertical shaft intersecting deposit (fig :3) Fig : 01
• 20. Figure : ‘2’ & ‘3’ d) Prospecting and exploration of a mineral deposit finally in the preparation of a detailed study of the feasibility is called prefeasibility. With the development and exploration of the mine, feasibility study is to proceed terminate work on the project. The following list of topics to be covered in the feasibility report-  Preface  General information  Environment concern  Geologic factors  Mineral reserves  Mining plan  Processing  Surface plant  Auxiliary and support facilities  Staffing  Marketing  Cost projection  Economic evaluation  Risk analysis  Profit projection e) Main opening schemes for ore deposits are as follows
• 21. Figure : layout of main access openings for an underground coal mine (top) drift , (center) slope and (bottom) shaft.
• 22. 11. (a)Define pitch. -1 (b)Write down the advantages of underground mining system. -2 (c)Sketch opening by inclined shaft. -3 (d)How you can select a mining method? -4 (e)Briefly describe about the components of hoist plant. -5 Answer to the question no: 11 a) Pitch- The inclination of a seam; the rise of a seam. b) The advantages of the underground mining are as follows-  Moderately high productivity.  Moderate mining cost.  Moderately high production rate.  Fair and good recovery.  Low to moderate dilution.  Suitable to mechanization.  Ventilation enhances with multiple openings. c) Opening by inclined shafts are as follows-  Opening by an inclined shaft sunk in the footwall rock.  Opening by an inclined shaft sunk through the deposit.  Opening by a side inclined shaft. Fig: Opening by inclined shaft d) Selection of a mining method is given below- There are many factors, both quantitative and qualitative, that must be evaluated in the choice of a mining method. These are the followings- i. Spatial characteristics of the deposit
• 23.  Size  Shape  Attitude  Depth ii. Geologic and hydrologic conditions  Mineralogy and petrography  Chemical composition  Deposit structure iii. Geotechnical properties  Elastic properties  Plastic behaviour  State of stress  Rock mass rating iv. Economic consideration  Reserves  Production rate  Mine life  Productivity  Comparative mining and capital costs v. Technological factors  Recovery  Dilution  Flexibility of the method  Selectivity of the method vi. Environmental concerns  Ground control to maintain integrity of opening  Subsidence or caving effect at the surface  Atmospheric control  Workforce  Comparative safety e) Components of hoist plant- The hoist plant consists of all those components of the mine plant that are necessary to elevate ore, coal, stone, or waste and to raise and lower personnel and materiel in the mine. Classified by location, they consist of the following:
• 24. I. Surface plant  Hoist room (headframe- or ground-mounted)  Hoist drum or sheave (imparts motion to rope)  Hoise electrical and mechanical equipment (prime mover, brake, clutch, controls)  Hoist ropes (steel wire strands, woven in a pattern or lay)  Headframe (tower or A-frame, steel or reinforced concrete)  Idler sheaves  Storage bins (ore and waste)  Skip dump mechanism (overturning or bottom dump II. Shaft plant  Skips (bulk transport)  Cages, elevators (personnel, materiel)  Shaft guides (tracks for skips and cage III. Underground plant  Dump and storage bin  Crusher (if size reduction required for hoisting)  Loading pocket  Personnel and materials-handling facilities Fig: Components of the hoist plant installed with a vertical shaft.
• 25. 12. (a)Define Chute. -1 (b)Classify Supported mining method. -2 (c)List out the materials used in roads in an underground mining. -3 (d)Describe the sequence of development and cycle of operations of longwall mining. -4 (e)Difference between capital cost & operating cost estimation associated With underground mining activities. -5 Answer to the question no: 12 a) A chute is a vertical or inclined plane, channel or passage through which objects are moved by means of gravity. b) Classification of supported mining method:-  Cut –and –fill stoping  Stull stoping  Square-set stoping. c) Materials for underground support:  Timber  Cement  Limes  Mortars  Concrete  Gunite  Natural Stone  Brickwork  Precast Concrete Blocks  Reinforced concrete  Steel  New materials for underground support d) Sequence of Development Longwall development is strikingly similar to development in room-and-pillar Mining. By referring to Figure 9.4, we can see how a coal mine is ideally laid out for either method of mining. Main entries are driven across the property, from which orthogonal panel entries divide the coal into large blocks, mineable by either the room-and-pillar or the longwall method. Continuous miners are used to develop the headgate and tailgate entry systems. Generally
• 26. continuous miner sections perform this task, though the continuous miners are sometimes equipped with integral roof bolters to enhance the advance rate. After the gate entries are developed, bleeders are normally driven at the inby extreme of the panels to allow for better ventilation of the longwall faces. When the panel entries are completed and the bleeders established, the longwall face is started from the inner bleeder entry (Trent and Harrison,). As a cut is taken across the face, the hydraulic supowing the roof behind to cave. The armored conveyor used to transport coal along the face is snaked forward by the supports, while the mining machine advances by means of a chain or ruck and pinion. As the coal arrives at the headgate, it is transferred from the chain- and-light conveyor to a belt conveyor (the belt is usually installed when the panel entries are driven). Additional support is often required in the entries, where cribs may supplement roof bolts Cycle of Operations The development cycle of operations is essentially the same as in the room- and-pillar mining method using continuous miners. Continuous Mining. Continuous mining is a method that has been practiced, primarily in coal, since about . The method uses a simplified cycle of operations, as follows: Production cycle mine +haul As in conventional mining, the auxiliary operations of roof control, ventilation,and cleanup must also be performed. The method depends heavily on the ruggedness and reliability of the continuous miner. The continuous miner breaks and loads the coal mechanically and simultaneously eliminates the steps of cutting, blasting, and loading. It is not, however, truly a "continuously operating machine. Maintenance, moving from face to face, and waiting for other production and auxiliary operations contribute to its inefficiency. Although more efficient
• 27. than conventional mining, the method is also subjected to simulation studies to improve its productivity. In the actual longwall operation, the cycle of operations is quite simple. The unit operations that must be conducted are the following: Mining (breaking and loading): shearer (normally a double-drum version),plow Haulage: armored chain-and-flight face conveyor, normal belt conveyor utilized in the headgate entry set. e) Clay Vein: a body of clay like materials that fills a void in coal bed Ground pressure- The pressure to which a rock formation is subjected by the weight of the superimposed rock and rock materials or by diastrophic forces created by movements in the rocks forming the earth's crust. Such pressures may be great enough to cause rocks compressional strength to deform and be squeezed Into and close a borehole or other underground opening not adequately strengthened by an artificial support, such as casing or timber Working Section: From the faces to the point where coal is loaded onto belts or rail cars to begin its trip to the outside. 13. (a)What is tunnel?-1 (b)Define is cross-cut? -2 (c)Describe the importance of mine ventilation?-3 (d)Describe CBM method and describe the functions of CBM method?-4 (e)What is the prospecting of underground mining system in Bangladesh?-5 Answer to the question no: 13 a) Tunnel: Main horizontal or near-horizontal opening, with access to the surface at both ends. b) Cross-cut: Tertiary horizontal opening, often connecting drifts, entries, or rooms; oriented perpendicularly to the strike of a pitching deposit; also breakthrough. c) The importance of mine ventilation – i. Good ventilation in underground mines gives the ability to remove and dilute harmful dust and gas. ii. The dust and gas can be a by-product of the ore being mined, explosives or machinery exhaust. Mine ventilation is provided via large intake and exhaust fans, pulling fresh air into the mine and extracting the unwanted dust and gases via internal ventilation ducts. iii. Volume is very important when providing good mine ventilation as it assists in managing and maintaining safe percentages of required carbon dioxide and
• 28. oxygen. Temperature also effects the workings of a good ventilation system, this is generally determined by mining engineers in accordance with safety laws and guidelines, and the type of mine it is being applied to. iv. It is of importance to maintain good ventilation in underground mines due to the risk of fatalities, explosions, carcinogen exposure and illness, sluggishness and low-productivity due to workers being exposed to insufficient breathable air. v. Due to the cost of creating and the ongoing cost of running ventilation systems, they often get pushed to the absolute limit of their ability. It is imperative for the safety of all mine workers that good ventilation is maintained consistently in underground mining situations. d) CBM –Coal Bed Methane (CBM extraction) is a method for extracting methane from a coal deposit. The functions of CBM method – i. Methane adsorbed into a solid coal matrix (coal macerals) will be released if the coal seam is depressurized. ii. Methane may be extracted by drilling wells into the coal seam. iii. The goal is to decrease the water pressure by pumping water from the well. iv. The decrease in pressure allows methane to desorb from the coal and flow as a gas up the well to the surface. v. Methane is then compressed and piped to market. vi. The objective is to avoid putting methane into the water line, but allow it to flow up the backside of the well (casing) to the compressor station. vii. If the water level is pumped too low during dewatering, methane may travel up the tubing into the water line causing the well to become "gassy". viii. Although methane may be recovered in a water-gas separator at the surface, pumping water and gas is inefficient and can cause pump wear and breakdown. e) The prospecting of Underground mining in Bangladesh –Barapukuria coal mine Petrobangla coal mining subsidiary is Barapukuria Coal Mining Co. Ltd (BCMCL) owns an underground coal mine at Barapukuria in the Dinajpur District. While initially designed to produce 1 million tonnes a year from a long wall mining operation,"[1] the mine has encountered strong community opposition, dissatisfaction of the workforce with the company and limited production. Approximately 70% of the output from the mine is supplied to the existing Barapukuria Coal Power Plant.[11] The 2,500-acre underground mine includes 650 acres of agricultural land on the surface. The International Accountability Project reports that mining operations at Barapukuria have destroyed roughly 300 acres of land, impacting about 2,500 people in seven villages, as land subsidence of over one meter in depth has destroyed crops and lands and damaged homes. People in 15 villages have also reportedly lost their access to water, as huge quantities of water pumped out for the Barapukuria mine caused a rapid drop in water levels.[12] The mine has been the subject of substantial community opposition and the subject of ongoing protests.
• 29. Underground Coal Gasification in Bangladesh Main source of energy fuel in Bangladesh is natural gas and day by day it is trimming the proven reserves. There are provisions of potential renewable energy resources like the solar, wind, tidal etc.; but the initiatives are very slow. Coal reserves and their prospects could not assure the nation as there are proven coal reserves of about 4,750 Mt (equivalent to 975 GM3 of gas, which is around 3 times greater than the present gas reserve in Bangladesh). Those coal reserves are discovered in the North-Western part of Bangladesh at the depth ranging 200- m. The special feature of the coal seams are found in the same geological formation and thickness is high (on average 38-64 m).One of the major issues, is the minable amount of the resources in conventional mining method. Barapukuria coal mine is under operation since and running a 250 MW coal fired power plant. But the mining method is not yet proven as suitable one, due to jointed layer thick coal seam (51 m) with faulty overburden and wider aquifer zone. The underground mining environment is hazardous including high temperature, suffocative humidity and releasing of unpredictable carboneus gases from the coal faces which make the life expectancy of this mine questionable. Maddhapara Granite Mining Company Limited (MGMCL) Maddhapara Granite Mining Company Ltd. Was established with multifold responsibilities of production of hard rock with daily production capacity of 5,500 M. tons from the underground mine, marketing & selling of the produced hardrock to different Government entities e.g. BBA, PWD, Roads & Highways, Water Development Board, Bangladesh Railway etc. 14. (a)What is country rock? -1 (b) Define advanced mining. -2 (c) Difference between gravity haulage & ramp. -3 (d) Determine shaft plant & discuss about the functions of shaft. -4 (e) What is blind shaft accessibility in underground mining & its advantages of ore disposal? -5 Answer to the question no: 14 15. (a) What is foot wall? -1 (b)Note down the characteristics of ore for sublevel stopping? -2 (c) Write the factor of development shrinkage stopping? -3 (d)Sketch the big hole open stopping? -4 (e)Discuss the important features of stop design? -5 Answer to the question no: 15 a) Footwall- Wall or rock under the ore deposit. b) The characteristics of ore for sublevel stopping:  Steep-dip the inclination of the footwall must exceed the angle of repose.
• 30.  Stable rock in both the hanging wall and the footwall.  Competent ore and host rock.  Regular ore boundaries. c) The Factor of development shrinkage stopping:  A haulage drift along the bottom of the stope.  Crosscuts into the ore underneath the stope.  Finger raise and cones from the crosscuts to the undercut.  An undercut or complete bottom slice of the stope 5 to 10m above the haulage drift.  A raise from the haulage level passing through the undercut to the main level above to provide access and ventilation to the stope. d) Sketch the big hole open stopping: Figure: Big hole open stopping e) The important features of stope design:  One or two large bridge cranes over the motor pits.  Easy access from several different directions for access to and around the cranes when they are in service for extended periods of time.  A motor pit and service area separate from the break-down motor pits for scheduled lubrication performed as part of a preventive maintenance program.  A separate area and equipment for tire mounting and repair.  A separate area for welding operations.  A separate enclosed area for recharging batteries.  Various work areas equipped with steel worktables or benches.  A separate area for washing and steam-cleaning equipment.  An office for the shop foreman computers, records, manuals, catalogs ,drawing and possibly a drafting table. The main pit areas should be visible from the office windows. 16. (a)What is conventional mining?
• 31. (a) Define ventilation raise. (b) Sketch open room combined system. (c) Explain the methods of blasting. (d) Note down the advantages and disadvantages of sublevel stoping system Answer to the question no: 16 a) The first fully mechanized underground mining method involving the insertion of explosives in a coal seam, the blasting of the seam, and the removal of the coal onto w conveyor of shuttle car by a loading machine b) Ventilation is the control of air movement, its amount and direction, although it contributes nothing to the production phase, of an operation. The lack of proper ventilation often will cause lower worker efficiency and decrease productivity, and increase accident rate. To ensure adequate ventilation of mine, provision is made For suitable path for the air to flow down the mine to the working places and suitable routes out of mine when it has become unsuitable for the further use. c) Sketch of open room combined system is given below:
• 32. d) The main method of breaking in underground mining of ore and non metallic deposit is blasting. When working soft manages ores, potassium salt, and refractory clays, extraction is performed by cutter loader. There are three methods of blasting.  Short-hole blasting  Long-hole blasting  Blasting by chamber charges Short-hole blasting is used with blast holes up to 5m deep and with greater depth long- hole blasting is used. Blast hole from 6 to 10m deep drilled by mounted or telescopic feed drills with the use of screwed jib holes. Short-holes are drilled in stoping face by drills and drilling rigs. Hand mounted and telescopic drills are used in small size faces, usually in thin ore bodies. Long-hole blasting has gained wide acceptance in mining of thick deposit in underground mining. It ensure high labour productivity of drillers and more safe and healthy labor condition since the holes are drilled from small size workings and long- hole drilling liberates far less dust than short-hole drilling. Long-hole drilling decrease the volume of development work and cut the ore extraction production cost. e)advantages and disadvantages of sublevel stoping: Advantages:  Moderate to high productivity  Moderate mining cost  Moderate to high production rate  Lends itself to mechanization, not labor intensive  Low breakage cost  Little exposure to hazardous conditions  Unit operation can be carried on simultaneously  Fair recovery (about 75%)  Modest dilution Disadvantages:  Fairly complicated and expensive development  Inflexible in mining plan  Longhole drilling requires precision  Large blast can cause significant vibration, air blast and structural damage. 17. (a) Define undercut. -1
• 33. (b) Coal mining equipment selection process? -2 (c) Explain the cycle of operations in cut and fill stoping. -3 (d) Illustrate VCR version of sublevel stoping. -4 (e) Write short notes on: -5 Answer to the question no: 17 a) Undercut: Low horizontal opening excavated under a portion of a deposit, usually a stope, to induce breakage and caving of the deposit; also a narrow kerf cut in the face of a mineral deposit to facilitate breakage. b) Coal Mining Equipment Selection: The selection of equipment for coal mining depends heavily on the dip of the coal seams to be mined. For room-and-pillar mining and for development of longwall operations, the pattern is to choose a continuous miner unit suited to its use, a section haulage system, a roof bolter, and any auxiliary equipment that is necessary. The traditional choice for a continuous miner is a drum-type machine with remote control and an integrated dust collector. For haulage, there are a number of choices: electric shuttle cars, diesel shuttle cars, full- dimension mining equipment and other continuous conveyor system. For roof control, the normal choice is a two-bottom bolter, with each bolter location protected by a hydraulic roof support system. c) The following operations are normally used: 1. Drilling: pneumatic or hydraulic percussion or rotary-percussion drills; handheld drill now avoided except in extremely rare situations; hole sizes normally 2 to 3 in. 2. Blasting: ammonium nitrate and fuel oil, slurries, emulsions; charging by cartridge or by bulk methods, firing electrically or by nonelectric methods 3. Secondary breakage: drill and blast, mudcapping, impact hammer. 4. Loading: load-haul-dump device, front-end loader, slusher. 5. Haulage: LHD, truck, rail
• 34. d) Illustrating Vertical crater retreat (VCR) version of sublevel stoping: Fig: VCR version of sublevel stoping e) Surface plant: The surface plant consists of a variety of facilities to provide the mine with necessary services. These include access roads and parking, transportation facilities, power supply, water supply, service and maintenance buildings, mineral processing plant, bulk storage, and waste disposal facilities for air, water, and solids. The surface facilities that are unique to understand mining are tha shaft collar and enclosure, headframe, bins, and hoist house. Shaft plant: The shaft plant consists of the facilities installed for material handling of ore, coal, or stone an associated waste and the means of transport of miners and material. It generally also includes systems for ventilation, drainage, power supply, and the communications .0 18. (a) What is the meaning of MSHA? -1 (b) Give a list of underground mine equipment’s. -2
• 35. (c) Write a short note about -3 i ) blasting circuit ii ) Fly ash (d) Classify the mine machines -4 (e) Explain the selection of roof control in coal mines. -5 Answer to the question no: 18 a) MSHA means Mine Safety and Health Administration. b) A list of underground mine equipment’s. i. Shuttle cars, ii. Roof bolters, iii. Personnel vehicles, iv. Cutting machines, v. Rock dusters, vi. Ventilation fans, vii. Scoops, viii. Longwall miners & ix. Continuous miners. c) Blasting Circuit: - i. It is an electrical circuit, ii. It is used to fire electric detonators, iii. Also used for blasting in mining sectors, Fly ash: - i. Finely divided particles of ash, ii. Resulting from the combustion of fuel, iii. Electrostatic precipitators are used to remove fly ash from the gases prior.
• 36. d)
• 37. e) Ground control is one of the primary tasks that any mining engineer must be followed, it is fundamental to both safety and productivity in the mine. The choices for ground control are fairly numerous. The following are the most common choices are--- i. Rock Bolts and Variations, ii. Mechanical point-anchor bolts iii. Resin-anchored bolts iv. Split-set bolts v. Swellex bolts vi. Combination-anchor bolts vii. Bolts with steel mesh viii. Bolt trusses ix. Grouted steel cable x. Grouted wooden dowels xi. Mechanical Supports xii. Timber sets xiii. Steel sets xiv. Yieldable steel arches and ring sets xv. Resin grouts xvi. Concrete Support xvii. Gunite sprayed-on linings xviii. Shotcrete lining xix. Formed concrete lining xx. Concrete grout xxi. Concrete crib rings xxii. Miscellaneous Supports xxiii. Wood cribs xxiv. Temporary hydraulic supports xxv. Powered mobile hydraulic supports xxvi. Freezing techniques xxvii. Chemical grouts 19. (a)What is blasting cap? -1 (b)Write the name of three level of Maddhapara hard rock mine with their height, length and Width. -2 (c)Discuss about combined system. -3 (d)Advantages and disadvantages of underground mining method. -4 (e)Briefly explain cut and fill system and It's types. -5 Answer to the question no : 19
• 38. a) Blasting cap: A detonator containing a charge of detonating compound which is ignited by electric current. Used for detonating explosives. b) The name of three level of Maddhapara hard rock mine:- 1. Ventilation level. Height: 20m Length: 230m 2. Sub level. Height: 20m Length: 230m 3. Production level. Height: 20m Length: 230m The width of the total pillar is 60m. c) Combined system: The combhinedining systems' are distinguished by dividing the level in uniformly alternating rooms and intervening pillars which are relatively close in size and are worked successively in two stages by different mining systems. The rooms are stopped in the first and the pillars in the second stage after extracting two or three (seldom the pillar more) adjacent rooms. By the method of room stopping, the combined systems may be divided into four groups which differ by the conditions of employment: 1) Open-room combined systems: the rooms are stopped by a variant of the sublevel or level stopping systems, the pillars are robbed by the level or sublevel caving. 2) Combined shrinkage systems: the room pillars are robbed among the stowed ore (aş the ore is discharged) by slice firing of the pillar from top to bottom or mass caving with undercutting. 3) Combined cut-and-fill systems: as stopping progresses the rooms get with a filling material, sometimes together with permanent timbering, the pillar surrounded with fill on both sides is robbed by slice or sublevel caving. 4) Combined systems of mining with subsequent filling of rooms: after extraction of rooms by the first or second class systems they are filled with a dry or hardening filling material and the pillars are robbed within the fill. d) Advantage of underground mining method:- (1) Moderately high productivity. (2) Moderate mining cost. (3) Moderately high production rate. (4) Low to moderate dilution. (5) Suitable to mechanization. (6) Ventilation enhances with multiple openings. Disadvantage of underground mining method:-
• 39. (1) Potential health and safety hazards exist, especially in coal mines. (2) Poor recovery (3) Ground stress and support loads increase with depth (4) Fairly high capital investment associated with mechanism. (5) Difficult to provide good ventilation. e) Cut and fill stopping system: cut and fill stopping is normally used in an overhand fashion. The ore is extracted in horizontal slices and replaced with backfill material. The backfilling operation is normally performed after each horizontal slice is removed. An estimated 3% of underground mineral production is derived from cut and fill stopping. Crandall list's the major types of fill as follows - 1. Waste fills. 2. Pneumatic fill. 3. Hydraulic fill with dilute slurry. 4. High -density hydraulic fill. Classification of cut and fill system: 1. Horizontal slicing system with filling. 2. Inclined slicing systems with filling. 3. Overhand systems with filling. 4. Descending slicing systems with filling. 5. Longwall systems with filling. 6. Systems with support and filling. 20. (a) Define roof jack. -1 (b) What is shaft shrinking? -2 (c) How to find way if underground collapse? -3 (d) Explain function of underground mine pumping. -4 (e) Describe various types of underground opening with sketch. -5 Answer to the question no : 20 a) A screw or pump type hydraulic extension post made of steel and used as temporary roof support. b) At the early stage of making a shaft needs some procedures. In the underground if the area is hard then the process of creating shaft become easier but if there is water it becomes hard to make a shaft and in the water shaft can’t be created. In this type of situation the water is freezed then the process of making a shaft go under work. And in which system the shaft is created after freezing the system is called shaft shrinking.
• 40. c) If underground collapse and someone stuck there it’s necessary to know the way of escaping from this danger. We can find way by the given options-  Air-the side of hot air flow is the way to shaft so it’s an indication of escaping and finding way.  Lamp- if one have lamp it can be used as a tool for finding way.  Drainage- if there is any water flow one can find way by following the flow direction. d) Pump is a device that moves fluids or other slurries by mechanical action. In underground mining pump is a major part of mining process. Slurry pumps, centrifugal pumps, magnetic drive pus, submersible pumps , borehole pumps, self priming pumps are used in mining industry depending on the fluid transfer and application needed. Mainly in underground mining pumps works for –  Abrasive sludge dewatering.  Mineral processing  Slurry transfer  Reagent(acid and chemical) dosing  Water supply  Waste water and trailing transfer e) Underground mining opening can be ranked in three categories. These are- 1. Primary : Main openings( e.g. shaft , slope) 2. Secondary : Level or zone openings( e.g. drift, entry) 3. Tertiary : Lateral or panel openings.(e.g. ramp, crosscut) Primary openings: Slope- primary inclined opening of a mine. Figure: main slope
• 41. Shaft-primary vertical opening through mine strata. Figure: shaft Secondary opening: Drift- A horizontal passage underground it follows the vein or a level or gallery. Figure: drift Tertiary opening:
• 42. Ramp: A secondary or tertiary inclined opening, driven to connect level, driven in downward direction and used for haulage. Crosscut: A passageway driven between the entry and its parallel air course or air ventilation purposes. 21. (a)Define underground openings? -1 (b)Briefly describe the directional terms? -2 (c)Distinguished surface mining and underground mining? -3 (d)Give the explanation of continuous mining and discuss about auxiliary operations of room and pillar mining. -4 (e)Describe state of stress about mine openings? -5 Answer to the question no : 21 a) Underground development openings can be ranked in three categories by order of importance in the overall layout of the mine: 1. Primary: main openings (e.g. shaft, slope) 2. Secondary: level or zone openings(e.g. drift, entry) 3. Tertiary: Lateral or plane openings (e.g. ramp, crosscut) b) Directional Terms: Breast: Advancing in near-horizontal direction; also the working face of an opening. Inby: Toward the working face, away from the mine entrance. Outby: away from the working face, toward the entrance. Overhand: Advancing in an upward direction.
• 43. Underhand: Advancing in a downward direction. c) Criteria of surface mining and underground mining Surface mining: 1. Work in shallow depth (>300m). 2. Low cost than underground mining. 3. Less risk than underground mining. 4. Environment damage must be occurred. 5. No need of ventilation system because it is an open air method. Underhground mining: 1. Work in depth of <300m. 2. Too much costly method. 3. It is too much risky. 4. No damage of environment sight. 5. Ventilation is first criteria of underground mining method. d) Continuous Mining: Continuous mining is a method that has been practiced, primarily in coal. The method uses a simplified cycle of operations ,as follows: Production cycle= mine + haul As in conventional mining, the auxiliary operations of roof control, ventilation, and cleanup must also be performed. The method depends heavily on the ruggedness and reliability of the continuous miner. Auxiliary Operations: 1. Health and safety: strata gas control, dust control, noise abatement. 2. Environmental control: flood protection, water treatment, subsidence control, remote monitor to sense atmospheric contamination. 3. Ground control: scaling of roof, roof control (roof bolts, timber, arch, crib, hydraulic jack), controlled caving. 4. Power supply and distribution: electric substation, diesel service station. 5. Water and flood control: pump station, drainage system (ditches, pipelines) 6. Cleanup and waste disposal: scoop” waste storage, hoisting, dumping. 7. Material supply: storage, delivery. 8. Maintenance and repair: shop facilities, parts warehouse. 9. Lighting: stationary lights, equipment-mounted lights. 10. Communications: radio, . 11. Construction: haulage, stoppings, overcasts. 12. Personnel transport: mantrips, shuttle jeeps, cages. e) State of Stress about mine openings: The vertical stress Sy = wL = (62.4SG/144)*L = 0.433SG*L lb/in2 Sy = wL = SG*L Pa For average rock with SG= 2.77 Sy = 1.2 in lb/m2. (L. in Pa). the horizontal stress Sx acting on a vertical plane is a function of the vertical stress: Sx = kSy In which k is a constant varying from 0 to <1.
• 44. Case 1: No confining pressure or restraint (k= 0); occurs at very shallow depths, close adjoining a bench face; Sx = 0 Case 2: No lateral deformation or strain, k = ( µ 1−µ ) Sy = 1/3Sy Case 3: Hydrostatic pressure (k = 1); occurs at great depth or in wet, squeezing and running ground: Sx = Sy Case 4: High lateral pressure due to techtonic forces ( k > 1); occurs in regions of recent orogenic or volcanic activity: Sx = kSy 22. (a)What is shaft? -1 (b)Write a short note about leaching and mine. -2 (c)Differentiate between post and step room and Pillar mining system. -3 (d)Advantage and disadvantage of room and pillar mining system. -4 (e)Explain about ventilation rise. -5 Answer to the question no : 22 a) Shaft- It is a long ,narrow part or section forming of a tool or club, the body of a spear or arrow or similar b) Leaching-Natural process by which water soluble substances (such as calcium, fertilizers, pesticides) are washed out from soil or wastes. These leached out chemicals (called leachites) cause pollution of surface and sub-surface water. Mine-1. It is an excavation made in the earth for the purpose of extracting ores, coal, precious stones, etc. 2.It is a place where such minerals may be obtained, either by excavation or by washing the soil. c) Condition of room and pillar mining system 1. Ore strength: weak to heard. 2. Rock strength: moderate to strong. 3. Deposit shape: tabular. 4. Deposit dip: low, prefer flat. 5. Deposit size: large areal extent; prefer seams with less than 15 ft thickness. 6. Ore grade: moderate.
• 45. 7. Ore uniformity: fairly uniform. 8. Depth: shallow to moderate. d) Advantage of room and Pilar mining system 1. Moderately high productivity. 2. Moderate mining cost. 3. Moderately high production rate. 4. Suitable to mechanization. Disadvantage of room and pillar mining system 1. Caving and subsidence occur with Pilar recovery. 2. Poor recovery without pillar extraction. 3. Ground stress and support loads increase with depth. 4. Potential health and safety hazards exit, especially in coal mines. e) It is a flow of air to the underground workings of a mine of sufficient volume to dilute and remove dust and noxious gases and to regulate temperature. The source flow these gases are equipment that runs on diesel engines, blasting with explosives,[1] and the orebody itself. The largest component of the operating cost for mine ventilation is electricity to power the ventilation fans, which may account for one third of a typical underground mine's entire electrical power efficient volume of air is required for proper ventilation. A bulk of electric power is required for driving fans. By installing variable speed control air quantity can be optimized hence the power. at every place in the mine where persons are required to work or pass, the air does not contain less than 19% of oxygen or more than 0.5% of carbon dioxide or any noxious gas in quantity likely to affect the health of any person; the percentage of inflammable gas does not exceed 0.75% in the general body of the return air of any ventilating district and 1.25% in any place in the mine; 23. (a)What is stope? -1 (b)What are the conditions of long wall top coal caving system? -2 (c)Differentiate between overhand and underhand systems. -3 (d)Describe the sublevel caving method and the sequence of mining. -4 (e)Briefly describe the classification of ore and rock caving systems. -5 Answer to the question no : 23 a) Stope: underground excavation made by removing ore from surrounding system. b) 1. Longwall mining is a highly mechanized underground mining system for mining coal.
• 46. it of longwall mining equipment consists of a coal shearer mounted on conveyor operating underneath a series of self-advancing hydraulic roof supports. 2. Longwall mining machines are typically 150-250 meters in width and 1.5 to 3 meters high. 3. Longwall miners extract "panels" -rectangular blocks of coal as wide as the face the equipment is installed in, and as long as several kilometers. 4. A layer of coal is selected and blocked out into an area known as a panel (A typical panel might be m long X 250 m wide). 5. Powerful mechanical coal cutters (Shearers) cut coal from the face, which falls onto an armored face conveyor for removal. 6Into an area of coal, or more commonly, retreat back between development tunnels(called "Gate roads") As a longwall miner retreats back along a panel, the roof behind the supports is allowed to collapse in a planned and controlled manner. c) Difference between post and step room and pillar mining systems: POST ROOM PILLAR MINING STEP ROOM PILLAR MINING 1.It is a combination of room and pillar and cut and fill stopping. 1.It is an adaptation of trackless mining to ore bodies where dip is too steep for rubber- tired vehicles. 2. Dip angles 20-25 degree. 2. Dip angles 15-30 degree. 3.Ore is recovered in horizontal slices. 3.Its applies to inclined ore bodies. d) Sublevel caving: Sublevel Caving is one of the most advanced mining methods. This method is usually undertaken when mining the orebody through an open pit is no longer economically viable. In Sublevel Caving, mining starts at the top of the orebody and develops downwards. Ore is mined from sublevels spaced at regular intervals throughout the deposit. A series of ring patterns is drilled and blasted from each sublevel, and broken ore is mucked out after each blast. Sublevel Caving can be used in orebodies with very different properties and is an easy method to mechanize. Advantages: • Inexpensive method that yields a large amount of muck • Highly mechanized process: - in most cases the drifts and tunnels are sufficiently large enough to introduce large trackless mining equipment • High efficiency: - with the repetitive nature of this mining method you can standardize all the mining activities • High amount of flexibility with production rates Disadvantages
• 47. • High level of dilution • Low recovery Mine development: 1.Production Shaft 2. Internal ramp 3. Sublevel extractions drifts 4. Production Headings 5. Orepasses 6. Main Haulage Level(s) 7. Mine Infrastructure Sequence of mining: All caving methods require extensive development prior to and during mining .In sub level caving,as much as 15to20% of the production takes place during development .The major portion of the development is horizontal, both on the haulage level and on the sublevels . e) Ore and rock caving system: Group decryptions: 1. Sublevel caving systems 2. Level self-caving systems 3. Level forced caving systems Ore and rock caving systems comprises the systems which differ from the systems of the preceding class in that, in addition to country rock, the ore mass cut previously at the bottom and sides also undergoes caving during stopping a result, the stopping area as it is formed gets filled with loose ore and caved barren rock on top. It would be more proper to divide these systems into two independent classes since falling of the stopping area with caved ore and the barren rock on top drastically change the conditions of discharge, delivery and loading of ore.The structural elements of these two systems have little in common. The ore and rock caving systems are characterized by complex preparation of block bottoms with funnels,trenches,and draw holes not used in slicing and caving systems and pillar systems with roof caving 24. (a) What is roof ? -1 (b)Define fossil fuel and formation. -2 (c)Distinguish between Longwall Top Coal Caving System and Room & Pillar Mining method. -3 (d)Briefly discuss about the uniqueness of underground mining system. -4
• 48. (e)Write short note on -5 Answer to the question no : 24 a) Back, Top and Overlaying surface of an excavation . b) Formation: Any assemblage of rocks which have some character in common, whether of origin, age, or composition. Often, the word is loosely used to indicate anything that has been formed or brought into its present shape. Fossil Fuel: Any naturally occurring fuel of an organic nature such as coal crude oil and natural gas. c) Longwall Top Coal Caving System: a) Applicable to very thick seam. b) Used of natural forces to aid the winning of coal. c) Increase recovery for only an incremental additional cost. d) Conventional longwall support system set up with roof supports AFC and shearer. e) Recovery is good more than room and pillar mining. Room and Pillar Mining: a) It is used for Flat Deposit. b) Natural roof support. c) Used for thick bed deposit. d) It is used for coal mine, iron and base metal ores e) Versatile for variety of roof conditions. d) A number of development steps are required for underground mining that are not necessary in surface mining. These are Factors in Mine Development o Locational Factor o Natural and Geologic Factor o Social-Economic-Political-Environment Factors Sequence of Development Other factors are, Most critical factors are ore and rock strength, the presence of groundwater, and the rock temperature gradient in the locality.
• 49. More skilled labour force may be required, financing may be more difficult because of increased risk, and subsidence may become the most important environmental concern. Limited excavation and relatively small openings are necessary for most underground mines. Development openings may be considerably more costly on a tonnage basis, and more types of excavations may be required. Underground mines normally must be provided with an artificial atmosphere as a means of ensuring that the quantity and quality of air are always adequate. e) Borehole: It is a vertical or near vertical opening .It is also called well logging. It gives us more information about the subsurface. By making borehole we know about the subsurface condition and formation of rock in the subsurface. Coal mine: An area of land and all structures, facilities, machinery, tools, equipment, shafts, slopes, tunnels, excavations, and other property, real or personal, placed upon, under, or above the surface or such land by any person, used in extracting coal from its natural deposits in the earth by any means or method, and the work of preparing the coal so extracted, including coal preparation facilities. British term is "colliery“. 25. (a)What do you mean by core sample? -1 (b)Define rock caving system. -2 (c)Difference between open stope system and shrinkage system. -3 (d)Give a brief of continuous mining. -4 (e)Short note: -5 Answer to the question no : 25 a) Core sample – A cylinder sample generally 1-5” in diameter drilled out of an area to determine the geologic and chemical analysis of the overburden and coal. b) Rock caving system – It covers the systems which are drastically different from other classes in that the stopping area is filled with caved rock in the course of stopping. Only a small face area is supported. c) Differences between haulage and hoisting systems – Haulage Hoisting
• 50. 1) Horizontal transport system. 1. Vertical or inclined transport system. 2) Haulage directly held along the floor of the seam. 2. Hoisting held in cages or on bogeys. 3) Mainly use the level and cross-cut to the pit bottom. 3. Hoisting happened through the shaft. 4) Mainly happened in hilly area by using adit or drift. 4. It is not happened in hoisting. d) Continuous mining – Continuous mining is a method that has been practiced primarily in coal. The method uses a simplified cycle of operations as follows: Production cycle = mine + haul As in conventional mining, the auxiliary operations of roof control, ventilation and cleanup must also be performed. The method depends heavily on the ruggedness and reliability of the continuous miner. The continuous miner breaks and loads the coal mechanically and simultaneously eliminates the steps of cutting, blasting, and loading. It is not, however, truly a “continuously” operating machine. Maintenance, moving from face to face and waiting for production and auxiliary operations contribute to its inefficiency. A though more efficient than conventional mining, the method is also simulation studies to improve its productivity. Continuous mining is practiced in coal, salt, potash, trona and other soft-rock applications. It is not normally effective in mining hard-rock formations. However, if a road header is employed in place of a continuous miner, the method can be used in harder rocks. The road header is a powerful continuous miner with smaller cutterhead designed to attack tougher materials. Its capabilities allow for additional use of room-and-pillar mining where the geologic conditions are unsuitable for a traditional rotating-drum continuous miner. e) Short note –  Factor of safety: The ratio ultimate breaking strength of the material to the force exerted against it. If a rope will break under a load of lbs and it is carrying a load of lbs. Its factor of safety is divided by which equals 3.  Fan / booster: A large fan installed in the main air current and thus in tandem with the main fan.  Exploration: The search for mineral deposits and the work done to proven or establish the extent of a mineral deposit. Alt: Prospecting and subsequent evaluation.
• 51. 26. (a)Define working face? -1 (b)What is function of vertical rise? -2 (c)Write a short note on - compressed air -3 (d)Short note on loading pocket and open end pillaring. -4 (e)Explain briefly haulage way. -5 Answer to the question no : 26 a) Working face: Any place in a mine where material is extracted during a mining cycle. b) Vertical raise: Vertical or near-vertical opening driven upward from a level to connect with level above, or to explore the ground for a limited distance above one level. c) Compressed air: Compressed air is commonly used as a power source due to the flexibility afforded by compressed air equipment and because of complications involved with the use of electric or diesel power in some locations underground. d) Loading pocket: Transfer point at a shaft where bulk material is loaded by bin, hopper and chute into a skip. Open end pillaring: A method of mining pillars in which no stump is left; the pockets driven are open on the gob side and the roof is supported by timber. e) Haulage way: Any underground entry or passageway that is designed for transport of mined material, personnel or equipment, usually by the installation of track or belt conveyor or rubber- tired vehicle. 27. (a)What is cage? -1 (b)Difference between cage and skip shaft. -2 (c)Short note on angle of draw and angle of repose. -3 (d)Explain various types of transport system. -4 (e)When we don't know the way of underground and we have no guide, how can we find the right way such as skip shaft? -5 Answer to the question no : 27 a) A conveyance used for moving workers and supplies below the surface, which is suspended from the hoist on steel wire rope. Cages are used in either vertical or incline mine shafts. All cages are required to contain necessary safety features. b) Difference between cage shaft and skip shaft are given below –
• 52. Skip Shaft Cage Shaft 1. Which transport ore and mineral from underground. 1. In a mine shaft, the device, similar to an elevator car, that is used for hoisting personnel and materials 2.The skip shaft height is 379.9m 2. The cage shaft height is 330.5 m c) Angle of draw - The surface position of the boundary between areas of subsidence and no subsidence is defined by the "angle of draw." Draw usually proceeds at an angle of 65– 75° to the horizontal. Angle of repose - The maximum angle from horizontal at which a given material will rest on a given surface without sliding or rolling. d) There are mainly two types of transportation system used in a mine. 1. Haulage 2. Hoisting 1. Haulage – Haulage means horizontal transportation system in a mine. There are many sub-classes in haulage system .Those are given below:  Locomotive: A locomotive or engine is a rail transport vehicle that provides the motive power for a mine car.  Adit: A horizontal or near-horizontal passage driven from the Earth’s surface into the side of a ridge or mountain for the purpose of working, ventilating, or removing water from a mine.  Dump Truck: A dump truck, known also as a dumper truck is used for transporting loose material (such as sand, gravel, or demolition waste) for construction. 2. Hoisting – vertical transportation systems are called hoisting. There are also many sub classes in this system. Those are-
• 53.  Conveyor belt - A conveyor belt is the carrying medium of a belt conveyor system. Used to transport large volumes of resources and agricultural materials, such as grain, salt, coal, ore, sand, overburden and more.  Slusher –  Ramp -The development of moderately inclined access ways from the surface to mining levels for haulage of ore, materials, waste, workers, and equipment.  Gravity flow hoisting system-  Blind Shaft- Those are the main transportation system in mining. 28. (a)What is slot? -1 (b)What do you mean by step room and pillar mining? -2 (c)Explain gasification process? -3 (d)Write short note on: -4  inclined shaft  mine ventilation (e)Sketch hydraulic filling systems. -5 Answer to the question no : 28 a) Vertical or inclined ore section excavated to open up for further stopping. b) Step room and pillar mining is an adaption or trackless mining to ore bodies where dip is too steep for rubber-tired vehicles. Although applications cannot be fully generalized, step room and pillar mining applies to tabular deposits with thickness from 2 to 5 m and dips ranging from 15 to 30 degrees. c) The conversion of coal into a gaseous fuel. Coal gasification is the process of producing syngas –a mixture consisting primarily of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), natural gas (CH4) , and water vapour (H2O)–from coal and water, air and/or oxygen.Historically, coal was gasified to produce coal gas, also known as "town gas". Coal gas is combustible and was used for municipal lighting, and heating, before the advent of large scale production of natural gas from oil well.
• 54. Fig: Coal gasification process. d) (i) Compressed air: Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is used as an energy source frequently in mining because of its flexibility over the use of diesel and electric power in locations underground. In some cases, compressed air may be used in ventilation systems. (ii)Mine ventilation: The provision of a directed flow of fresh and return air along all underground roadways, traveling roads, workings, and service parts. Mine ventilation provides a flow of air to the underground workings of a mine of sufficient volume to dilute and remove dust and noxious gases (typically NOx , SO2, methane, CO2 and CO) and to regulate temperature. The source of these gases are equipment that runs on diesel engines, blasting with explosives, and the ore body itself.
• 55. e. Sketch hydraulic filling systems. Fig: hydraulic filling systems 1=hopper,2=Mixing chute,3=Giant,4=Filling pipeline,5=pipeline for supply of clarified water to giant,6=clarifier,7=water pipeline,8=pump,9=collector,10=workings with drainage ditches,11=filtering sreens,12=worked out area 29. (a)what is leaching? -1 (b) Define mine, mining, mining engineering? -2 (c) Illustrate opening by adit and blind shafts? -3 (d) Sketch opening by adits on strike and show permanent adit in footwall, waste pile, Level Ore adits, ore pass, cross cut? -4 (e)How many types of principle scheme of level of development & it's described? Answer to the question no : 29 a) Leaching - A chemical process for the extraction of valuable minerals from ore; also, a natural process by which ground waters dissolve minerals, thus leaving the rock with a smaller proportion of some of the minerals than it contained originally. b) Mine: an excavation made in the earth to extract minerals. Mining: the activity, occupation, and industry concerned with the extraction of minerals. Mining engineering: the practice of applying engineering principles to the development, planning, operation, closure, and reclamation of mines. c) Opening by adit and blind shafts are as follows: (i) Two permanent adits.
• 56. (ii) Blind vertical shaft. (iii) Inclined shaft d) Opening by adits on strike are as follows: (i) Permanent adit in footwall (ii) Waste pile (iii) Level ore adits (iv) Ore pass (v) Cross cut e) There are two principal schemes of level development: (a) sequential (b) Parallel. Sequential development is used in thick ore bodies when large ore reserves in the level determine prolonged time of mining. To accelerate the development of the level, temporary blind shafts are sometimes sunk through the foot wall rock or the deposit. This method is employed only in exceptional cases. In parallel development, several development workings are driven simultaneously at several levels. This method has several advantages over sequential development: lower cost of sinking
• 57. the main shaft to several levels simultaneously; detailed prospecting of the ore body to a considerable depth, which simplifies the mining plan; favorable conditions for stoping owing to preliminary drainage. 30. (a) What is collar? -1 (b)Define conveyer belt, waste, berm? -2 (c)Difference between overhand and long wall system.-3 (d)Briefly describe the characteristics of ores and country rock? -4 (e)Sketch and explain cut and fill system?? -5 Answer to the question no : 30 a) The term applied to the timbering or concrete around the mouth or top of a shaft. b) Conveyer: An apparatus for moving material from one point to another in a continuous fashion. This is accomplished with an endless procession of hooks, buckets, wide rubber belt etc. Berm: A pile of mound of material capable of restraining a vehicle. Waste: The rock and mineral which must be removed from a mine to keep a mining scheme practical, but which has no value. c) Overhand system Longwall system 1. Advancing in an upward direction. 1. Advancing in a dip direction. 2. In open stope overhand systems are used to mine steeply dipping veins. 2. In open stope longwall systems are used for mining flat, more seldom inclined, ore bodies of average.
• 58. 3. Sheet deposits from 0.6 to 0.3 thick. 3. Ore bodies 10m to 12m thick. d) Strength and stability are most vital characteristics of all the physical and mechanical properties of ores and country rock, which determine the choice of the mining method and system to be used. Rock strength determined by a set of many physical and mechanical properties (hardness, toughness, jointing, lamination, presence of foreign inclusions and intercalations) influences the choice of the mining system, machine and tools to be used for working, mining equipment and productivity, consumption of material and the cost of extraction. Standards and consumption rates are determined, depending on physical and mechanical properties, by rock classification elaborated for individual process such as drilling or firing. For underground mining, the stability of ore and country rock is of no less importance than the rock strength. The importance of this characteristic manifests itself in the fact that the method of supporting the massive of ore and rock surrounding the worked-out space is adopted as the main feature for classification of the ore deposit underground mining systems. Apart from physical and mechanical properties of rock, massive stability is affected by various external conditions such as the mine working depth from the earth surface, its position with respect to the horizon, and the cross section dimensions of the working. Unstable ores and rock which allow small exposure of the roof that demand strong supporting immediately after extraction. e) After selecting the cut and fill system variant, its parameters length, level interval, slice thickness, and drift top and bottom pillar thickness should be determined. The schemes of