JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech III Year SURFACE MINING TECHNOLOGY Previous Question Paper (March - 2021 - R18)

The selection of the mode of entry into an opencast mine is critical for operational efficiency and safety. The primary factors influencing this choice include:

• Topography and Terrain: The natural surface profile determines whether a box cut, trench, or hillside entry is feasible. Steep terrain may necessitate switchback haul roads or conveyor systems.
• Depth and Geometry of the Deposit: Shallow deposits may allow for simple benching from the surface, while deeper deposits require complex ramp systems or spiral entries to maintain safe gradient limits.
• Geological Conditions: The nature of overburden and ore (competency, stability, and presence of water) dictates the required slope angles and the stability of entry points.
• Production Capacity: High-volume operations require wide, multi-lane haulage ramps, whereas smaller mines might utilize simpler, narrower access points.
• Equipment Constraints: The turning radius and grade-climbing ability of the chosen hauling fleet (trucks vs. conveyors) directly influence the design of the entry ramp.
• Economic Factors: The cost of stripping overburden to create an entry must be balanced against the long-term savings in haulage costs and operational cycle times.

Surface mine planning is a systematic process aimed at optimizing resource extraction while ensuring safety and profitability. The key elements include:

1. Geological Modeling: Establishing a precise 3D model of the deposit based on exploration data, including ore grade distribution, structural geology, and rock mass characteristics.
2. Pit Limit Optimization: Utilizing algorithms like the Lerchs-Grossmann method to determine the ultimate pit limit, defining the boundary where the cost of extraction equals the revenue generated.
3. Production Scheduling: Sequencing the extraction process over the life of the mine to manage cash flow, meet grade blending requirements, and ensure consistent output.
4. Waste Management and Disposal: Planning the location and capacity of external and internal waste dumps, ensuring stability and minimizing the haulage distance for overburden.
5. Haulage and Infrastructure Design: Designing the layout of haul roads, ramps, workshops, and processing plants to optimize cycle times and minimize operational bottlenecks.
6. Safety and Environmental Planning: Incorporating slope stability analysis, drainage management, and progressive reclamation strategies to comply with regulatory standards and minimize the ecological footprint.
7. Economic Evaluation: Conducting sensitivity analysis on capital and operating costs, commodity prices, and discount rates to verify the project's net present value (NPV).