Mine Development and Mining Methods MCQs Questions & Answers | Mining Engineering

Definition of Mine Development:
Mine development refers to the set of activities undertaken to prepare a mineral deposit for production. It involves the construction of shafts, adits, declines, drifts, crosscuts, and other underground or surface infrastructure required to reach and access the ore body. This phase comes after exploration and before the actual extraction of ore.

Correct Answer: Option C: Accessing ore body
The primary purpose of mine development is to access the ore body so that it can later be extracted efficiently and safely. Development creates the physical infrastructure that allows workers, equipment, ventilation, and materials to reach the ore. Without proper development, mining cannot begin.

Key components of mine development include:
• Shafts – Vertical openings used for transporting miners, equipment, and ore.
• Declines or ramps – Inclined tunnels that provide vehicle access between levels.
• Drifts and crosscuts – Horizontal passages used to reach the ore body and provide pathways for ventilation, drainage, and utilities.

All these elements are essential for setting up the operational framework of a mine, making ore accessible for subsequent extraction.

Explanation of Other Options:
Option A: Extraction of ore
Extraction is the next stage after development. While development may involve limited ore removal, its main goal is not extraction but preparation.

Option B: Ventilation planning
Ventilation is an important part of mine design but is not the primary goal of development. It is planned as part of the overall infrastructure to support access and safe working conditions.

Option D: Waste disposal
Waste disposal is a part of mine operations and environmental management. It is not a core function of development itself, though development work may include access to waste storage areas.

Conclusion:
The correct answer is Option C: Accessing ore body, as mine development is fundamentally aimed at creating the necessary infrastructure to reach and prepare the ore body for mining operations.

Definition of Adit:
An adit is a nearly horizontal or gently inclined tunnel driven from the surface into the side of a hill or mountain to access an underground mineral deposit. Unlike vertical shafts, adits provide direct access from the surface without the need for hoisting systems. They are commonly used when the ore body is located in hilly or mountainous terrain and can be reached by tunneling into the hillside.

Correct Answer: Option B: Adit
The correct answer is Option B: Adit because an adit is specifically defined as a horizontal or slightly inclined opening driven from the surface to access a mineral deposit. Adits are used for multiple purposes such as providing access for miners and equipment, enabling natural drainage of water from the mine, and serving as entry points for ventilation.

Adits are cost-effective in suitable topographies because they eliminate the need for vertical hoisting and can also be used for transporting ore and waste using rail or conveyor systems. They are particularly common in underground mining operations where the ore body is close to the surface but located within a hillside.

Explanation of Other Options:
Option A: Shaft
A shaft is a vertical or near-vertical opening driven downward from the surface to access underground ore bodies. It is not horizontal, so it does not match the description in the question.

Option C: Stope
A stope is the excavated area where ore is actually mined, typically located underground. It is not an access tunnel and is not driven from the surface.

Option D: Raise
A raise is a vertical or inclined opening driven upward from a lower level to a higher level in the mine. It is the opposite of a shaft and is also not driven from the surface.

Conclusion:
Therefore, the correct answer is Option B: Adit, as it is the only option that accurately describes a horizontal opening driven from the surface to access a mineral deposit.

Definition of Cut and Fill Mining:
Cut and Fill is an underground mining method used primarily in steeply dipping, irregular ore bodies. In this method, the ore is extracted in horizontal slices, usually starting from the bottom of the ore body. After each slice is removed, the void is filled with waste rock, tailings, or other backfill material to provide ground support and a working platform for the next slice.

Correct Answer: Option B: Cut and Fill
The correct answer is Option B: Cut and Fill because this method involves the extraction of ore in horizontal slices from the bottom upward. Once a horizontal layer or "cut" of ore is removed, the resulting space is immediately backfilled to maintain stability. Then the next slice is mined on top of the backfilled material. This sequence is repeated until the entire ore body is mined.

This method is particularly suitable for ore bodies that are irregular in shape or structure and where selective mining is required. It provides excellent control over ore recovery and dilution and ensures worker safety by maintaining continuous ground support.

Explanation of Other Options:
Option A: Room and Pillar
Room and Pillar involves mining out "rooms" of ore while leaving "pillars" to support the roof. It is typically done in flat or gently dipping deposits and does not proceed in horizontal slices from the bottom upward.

Option C: Block Caving
Block Caving is a mass mining method where a large section of ore is undercut and allowed to collapse under its own weight. It is not performed in horizontal slices, nor does it progress upward in a controlled slicing manner.

Option D: Shrinkage Stoping
Shrinkage Stoping involves mining upwards in vertical stopes and temporarily storing broken ore in the stope to provide a working platform. Although it moves upward, it does not use horizontal slicing and backfilling like cut and fill.

Conclusion:
Therefore, the correct answer is Option B: Cut and Fill, as it is the mining method that involves extracting ore in horizontal slices starting from the bottom and advancing upwards, with each slice being backfilled to support the subsequent operations.

Underground Mining Methods:
Underground mining methods are employed when mineral deposits are located deep beneath the surface, making surface mining impractical or impossible. These methods involve excavating ore bodies from within the earth, requiring extensive underground infrastructure and specialized techniques.

Open-Pit Mining:
Open-pit mining, also known as open-cast mining, is a surface mining technique where a large pit is excavated to access mineral deposits near the surface. This method is the opposite of underground mining.

Shrinkage Stoping, Sublevel Stoping, and Cut and Fill:
Shrinkage stoping, sublevel stoping, and cut and fill are all underground mining methods. They involve various techniques to extract ore from underground, including creating openings within the orebody and supporting the surrounding rock.

Correct Answer: A
The correct answer is Option A: Open-pit mining because it is explicitly a surface mining method, not an underground method. The other options (shrinkage stoping, sublevel stoping, and cut and fill) are all established underground mining techniques.

A vertical or near-vertical excavation used for transportation of men and material is called:
Option B: Shaft

First, let's define the terms involved:
Shaft: A deep, vertical, or near-vertical excavation in the earth, usually cylindrical in shape, used for transporting personnel, materials, and equipment between the surface and underground workings of a mine.
Drift: A nearly horizontal passageway or tunnel in a mine, usually driven from a shaft or another drift.
Crosscut: A horizontal or nearly horizontal passageway in a mine that intersects other workings (like drifts or veins) at an angle, usually connecting them.
Raise: An inclined or vertical passage driven upwards from a lower level to a higher level in a mine. It is often used for ore extraction, ventilation, or access.

The question asks for the term describing a vertical or near-vertical excavation used for transportation. A shaft precisely fits this description. Shafts are specifically designed and constructed for vertical transportation, incorporating features like hoisting systems for efficient movement of people and materials.

Drifts, crosscuts, and raises are all underground passages, but they are not primarily vertical and are not designed for the main transportation of personnel and materials in the same way a shaft is. Therefore, options A, C, and D are incorrect.

Low-grade ore body: An ore body with a relatively low concentration of valuable minerals. This means that a large volume of rock must be mined to extract a worthwhile amount of valuable material.

Large-scale ore body: A very extensive ore deposit, implying significant size and volume.

Now, let's analyze why Block Caving is the most suitable method:

Block Caving is a bulk mining method designed for large, low-grade ore bodies. It involves creating an undercut at the bottom of the ore body to initiate a controlled collapse of the ore. The broken ore then flows downwards through draw points, where it is collected and transported to the surface. This method is highly efficient for low-grade ores because it allows for the extraction of large volumes of material at a relatively low cost per ton. The scale of operation is ideally suited to the vast size of large ore bodies.

Why other options are less suitable:

Shrinkage Stoping: This method is suitable for steeply dipping, high-grade ore bodies. It involves mining in a series of levels and filling the stopes (excavations) with broken ore. This makes it unsuitable for low-grade deposits, where the dilution of ore with waste rock would reduce profitability.

Room and Pillar: This method involves creating rooms separated by pillars of ore. It’s more suitable for relatively flat-lying, tabular ore bodies. While it can handle some scale, it's not as efficient for the extreme volumes found in large, low-grade deposits. The percentage of ore left in pillars as support reduces overall extraction.

Cut and Fill: This method involves mining in horizontal slices, with waste rock used to create fill. While it can be used for steeply dipping ore bodies, it's generally not economically viable for extremely large, low-grade deposits due to higher costs associated with the filling process.

In summary, Block Caving is the most efficient and economical method for extracting valuable minerals from large, low-grade ore bodies due to its bulk mining nature and high extraction rate.

Crosscut Definition:
A crosscut, in the context of mine development, is a horizontal or nearly horizontal passageway driven from one mine workings to another, typically at right angles (or "crosses") to the main haulage ways or other drifts. It's not just any tunnel; it serves a specific purpose within the mine layout.

Correct Answer: Option D: Connect drifts
The primary function of a crosscut is to connect two or more separate drifts (or other mine workings). Drifts are essentially tunnels that follow a specific geological structure, like an ore body or a specific rock layer. Crosscuts are strategically placed to establish connections between these drifts, enabling various crucial operations. This connectivity is fundamental for multiple reasons, including:
• Improved access: Connecting drifts allows easier and faster access to different parts of the mine, improving transportation of materials and personnel.
• Enhanced ventilation: Crosscuts play a critical role in mine ventilation by providing alternate pathways for airflow, helping to dilute harmful gases and provide fresh air to various sections.
• Support for other operations: Crosscuts can facilitate other operations, such as access for exploration or development of new sections, improved access for ground control measures, or providing multiple escape routes.

Why other options are incorrect:
Option A: Access ore body: While a crosscut *might* intersect an ore body, its primary purpose is not to directly access the ore. Access to the ore is usually achieved via drifts or other specific development workings designed to follow the ore's geological configuration. Crosscuts aid in access indirectly by connecting these ore-accessing drifts.
Option B: Drain water: Water drainage in mines is typically handled by dedicated systems like sumps, pumps, and drainage galleries. Although a crosscut *could* incidentally aid in water drainage by providing an additional pathway, it is not its primary function.
Option C: Provide ventilation: While crosscuts contribute to ventilation, as mentioned above, their main purpose is not solely to provide ventilation. Ventilation is usually a more complex system involving shafts, fans and dedicated ventilation pathways, which crosscuts support, but don't replace.

Definition of Raise:
A raise in mining is a vertical or steeply inclined underground opening that is driven upward from a lower level to a higher level. It is commonly used to connect different levels of a mine, facilitate ventilation, provide ore transfer routes, or create access between working areas.

Correct Answer: Option C: Upward from a lower level
The correct answer is Option C: Upward from a lower level because a raise is specifically driven upward from an existing underground level. It is created by drilling and blasting upward through the rock, or using mechanical raise-boring methods.

Raises are essential for a variety of functions in a mine, including:
• Ventilation raises to circulate fresh air
• Ore passes to transfer broken ore to lower levels
• Manways to allow personnel movement between levels

The construction of a raise requires careful planning and safety measures due to the challenges of working in an upward direction, including rock fall risk and ventilation constraints.

Explanation of Other Options:
Option A: Downward from the surface
Driving downward from the surface creates a shaft, not a raise.

Option B: Horizontal from shaft
A horizontal opening driven from a shaft is called a drift or crosscut, not a raise.

Option D: Vertical from adit
An opening driven vertically from an adit would typically be a shaft or winze, depending on the direction, but it is not classified as a raise unless it is driven upward from a lower level.

Conclusion:
Therefore, the correct answer is Option C: Upward from a lower level, as this accurately describes the standard direction and purpose of driving a raise in underground mining operations.

Definition of Room and Pillar Mining:
Room and Pillar mining is an underground mining method used primarily for extracting flat or gently dipping, tabular ore bodies. In this method, "rooms" of ore are mined out while leaving behind "pillars" of unmined material to support the roof of the mine. The layout resembles a grid-like pattern of openings and pillars.

Correct Answer: Option C: Room and Pillar
The correct answer is Option C: Room and Pillar because this method is specifically designed for flat, tabular ore deposits. The geometry of the method allows for efficient ore recovery while maintaining structural integrity through the use of support pillars.

Room and Pillar is commonly used in coal mining, as well as in deposits of potash, gypsum, and salt. The design of the pillars is based on rock mechanics principles to ensure they can support the overburden without collapsing. In some cases, after primary extraction, pillars may be partially or fully removed in a process called "pillar recovery" or "retreat mining."

Explanation of Other Options:
Option A: Shrinkage Stoping
Shrinkage stoping is used for steeply dipping ore bodies, not flat ones. It involves mining upward and storing broken ore in the stope to provide a working platform.

Option B: Block Caving
Block caving is suitable for massive, lower-grade ore bodies that are mined by undercutting and allowing the rock to cave under gravity. It is not ideal for thin, flat deposits.

Option D: Sublevel Caving
Sublevel caving is used in steeply dipping ore bodies and involves controlled caving of both ore and waste. It is not optimal for flat, tabular deposits.

Conclusion:
Therefore, the correct answer is Option C: Room and Pillar, as it is the most suitable mining method for extracting ore from flat, tabular deposits while maintaining ground stability through the use of pillars.

A decline in mining is an inclined tunnel driven from the surface into the mine.
Declines are not exclusively used for a single purpose; they serve multiple functions in mine development.
Option A: Drainage only is incorrect. While declines can be used for drainage, this is not their primary purpose. Drainage is often a secondary benefit, or a consideration in their design and placement.
Option B: Hoisting ore is incorrect. While ore can *sometimes* be hoisted using a decline, it's far more common to use shafts or ramps for main ore hoisting because those structures can handle higher volumes and steeper angles efficiently. Declines are generally less efficient for large-scale ore transport.
Option C: Surface ventilation is incorrect. Ventilation is crucial for mine safety, but declines aren't primarily designed for this purpose. Ventilation is usually achieved through a combination of shafts, raises, and other ventilation openings specifically designed to create airflow throughout the mine.
Option D: Access by vehicles is the most accurate answer. Declines provide inclined access for vehicles (like trucks, loaders, or smaller personnel carriers) to transport personnel, equipment, and materials to and from the underground workings. This is their main function. The grade (slope) of the decline is designed to accommodate vehicles and their operational needs. A decline offers a more flexible and potentially less costly access solution compared to a vertical shaft which requires substantial infrastructure for hoisting and personnel transport.