JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III Year SURFACE MINING TECHNOLOGY Previous Question Paper (October - 2020 - R13)

Surface mining in India is the dominant method of mineral extraction, accounting for over 90% of the country's total mineral production. The sector is characterized by large-scale open-cast operations, particularly in coal, iron ore, limestone, and bauxite.

Key aspects of the current status include:

• Coal Dominance: The vast majority of India's coal production is derived from massive open-cast mines managed by Coal India Limited and its subsidiaries. These mines utilize high-capacity heavy earth-moving machinery (HEMM) such as draglines, electric rope shovels, and large-capacity dumpers to handle high stripping ratios.
• Technological Advancements: There is a significant shift toward the adoption of surface miners for selective mining, which eliminates the need for conventional drilling and blasting. This technology is increasingly used in coal and limestone sectors to improve productivity, quality control, and environmental compliance.
• Scale of Operations: Operations have transitioned from manual or semi-mechanized methods to fully mechanized systems. Mega-projects are common, involving deep-pit mining that requires sophisticated slope stability monitoring and advanced dewatering techniques.
• Environmental and Social Challenges: As mines expand, the industry faces stringent environmental regulations regarding land reclamation, dust suppression, and water management. The status is also defined by the increasing complexity of land acquisition and the implementation of corporate social responsibility (CSR) initiatives for project-affected communities.
• Safety and Sustainability: The regulatory framework, overseen by the Directorate General of Mines Safety (DGMS), emphasizes rigorous safety protocols. Sustainability is becoming a core focus, with companies investing in green mining practices, renewable energy integration, and the transition toward digital mining solutions to optimize resource recovery.

In summary, surface mining remains the backbone of the Indian mining industry, driven by the need to meet the country's growing energy and industrial raw material demands through large-scale, mechanized, and increasingly technology-driven operations.

In opencast coal mining, a bench is a horizontal slice or layer of material being excavated. The formation of benches is essential for safety, operational efficiency, and the systematic extraction of coal and overburden. The process involves creating a series of steps that allow for the simultaneous operation of drilling, blasting, loading, and hauling equipment.

The formation process follows these key steps:

• Bench Height Determination: The height is selected based on the reach of the loading equipment (e.g., shovel or excavator) and the geological stability of the strata.
• Drilling and Blasting: Vertical or slightly inclined blast holes are drilled into the bench face. Explosives are detonated to fragment the rock or coal, creating a muck pile at the toe of the bench.
• Loading and Hauling: Excavators load the fragmented material into dump trucks or conveyors, which transport it to the surface or disposal sites.
• Bench Advancement: As the material is removed, the bench face advances forward into the deposit, creating a new working area.

Key components of a bench include the bench height (vertical distance between the top and bottom of the bench), bench width (the horizontal distance available for equipment movement), bench face angle (the slope of the vertical face), and the berm (a safety ledge left between benches to catch falling debris).

Sketch description: A cross-sectional view shows a terraced structure resembling a staircase. Each step represents a bench with a flat top (bench floor), a near-vertical face (bench slope), and a horizontal ledge (berm) between the top of one bench and the base of the next. The overall slope of the mine wall is defined by the angle connecting the crest of the top bench to the toe of the bottom bench, ensuring structural stability.