Mine Development And Mining Methods - Study Mode

[#241] In mine development, what is the primary function of a crosscut?
Correct Answer

(D) Connect drifts

Explanation

Solution: 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.

[#242] Declines in mines are inclined tunnels primarily used for:
Correct Answer

(D) Access by vehicles

Explanation

Solution: 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.

[#243] What is the key factor in choosing between vertical crater retreat and sublevel stoping?
Correct Answer

(B) Orebody geometry and height

Explanation

Solution: Vertical Crater Retreat (VCR) and Sublevel stoping differ in layout and fragmentation.The correct answer is: Orebody geometry and heightVCR is good for tall, steep bodies

sublevel stoping for medium height.Geometry directly affects method suitability.

[#244] A "box cut" is:
Correct Answer

(A) Initial open cut to access underground ore

Explanation

Solution: A box cut is Option A: Initial open cut to access underground ore First, let's define what a box cut is in the context of mining engineering. A box cut is a type of open-pit mining operation. It's an initial excavation, typically rectangular or square in shape, used to gain access to underground ore bodies. The purpose of a box cut is to provide a surface opening for further underground development. From this initial opening, various underground mining methods can be employed to extract the ore. This approach is particularly useful when the ore body is situated beneath a layer of overburden (the layer of rock or soil above the ore deposit) that needs to be removed before underground workings can commence. Why other options are incorrect: Option B: A stoping method is incorrect. Stoping refers to a variety of underground mining methods where ore is extracted from a stope (an underground excavation). A box cut is not a stoping method itself
rather, it is a pre-requisite for accessing the underground area where stoping might later be used. Option C: A rock bolting technique is incorrect. Rock bolting is a ground support method used to reinforce and stabilize underground excavations. It's a separate technique used *after* access to the underground area has been established (e.g., via a box cut), not the access method itself. Option D: An ore pass support is incorrect. An ore pass is a chute or passageway used to transport ore from underground workings to the surface. Again, this is a feature of the underground mine *after* access has been gained
it is not the initial access method.

[#245] Which equipment is commonly used in mechanized mine development?
Correct Answer

(C) Jumbo drill

Explanation

Solution: Jumbo drill is a mechanized drilling machine for tunnel and drift development.The correct answer is: Jumbo drillIt ensures precision drilling of blast holes in hard rock.Draglines are for surface mining
dredgers for marine mining.