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The massive deposit of medium-grained, white-colored sandstone of about 20 m thick, is located immediately above the coal seam in Quarry No. 2, resulted lesser yield due to lower powder factor (m3/kg) and over-sized boulder formations, specifically from the stemming zones at Chotia Opencast Coal Mine of M/s Prakash Industries Limited, which was operating at a depth of about 30 to 40 m with an average bench height of 5.5 m. The criticality of the problem led to the rectification of the blast design parameters through incorporation of pilot holes and pocket charges, decked charges, air-decking, evolution of static energy distributions, and fragment data analysis for establishing optimized design patterns with available machinery. Several test blasts along with on-site testing of explosive quality, rebound hardness tests of overlying strata, and rearrangements of firing patterns through surface delay connections were considered for adopting the best-suitable blast pattern for the mine. Generalized and perceptible inferences were made to apply the results in other mines with similar kinds of problems. [ABSTRACT FROM AUTHOR]

Stabilization of highwall slope by implementing presplit blasting and productivity enhancement by improving the powder factor using controlled blasting at Sharda project of South Eastern Coalfields Ltd. (SECL) was the endeavour of the research team of CSIR-CIMFR in the first trench highwall mining of India. Good fragmentation was achieved through improved rock-explosive interactions and redefined design parameters in the trench which had restricted width and lesser initial powder factor (in m³/kg) due to varying rock-geologic and rock-explosive characteristics. Through systemic analysis of blast-results and implementation of scientific theories combined with the usage of rock parameters and its physico-mechanical properties, it could possible to achieve around 2.0 m³/kg powder factor instead of 1.3-1.4 m³/kg maintaining stable highwall benches with 700or more slope angle. The work led to huge cost benefits in explosive consumption for the company i.e. M/s Cuprum Bagrodia Ltd. and also markedly reduced the environmental implications from production blastsduring day-to-day operations. [ABSTRACT FROM AUTHOR]

A comprehensive review of the mechanism of rock breakage by blasting is presented. Topics covered include the properties of rock and rock mass and their influence, property of explosives including strength of a commercial explosive, the density of the majority of explosives, detonation velocity and water resistance of explosives.

This paper presents basic issues concerning the pit slope stability with special reference to the stability of highwall slopes in Indian coal mines. Scientific design of highwall slopes along with the implementation of an appropriate slope monitoring plan are suggested as the key inputs towards effective planning and management of highwall slopes. [ABSTRACT FROM AUTHOR]

High-wall mining, an extension to open cut mining, commonly use auger and continuous highwall mining system. Rock properties and structural geology' of rock are the vital parameters for designing highwall mining. The limitations of basic equations/models developed for computing web and barrier pillar strength, geological conditions and improper execution of highwall mining are the key causes for instability of highwall. Meticulous monitoring of displacement rates is imperative to evaluate the stability of the highwall and, in turn, safety of men, material and machinery. There are several land based, airborne and satellite based techniques of highwall movement monitoring systems. Frequency of measurement depends on the rate of ground movement. Total station can be used for daily monitoring whereas slope stability radar can be adopted for continuous monitoring if required. A study was conducted at OC-II of Singerani Collieries Company Ltd. by Total Station. The safe limits of highwall stability in terms of strain are discussed in the paper. [ABSTRACT FROM AUTHOR]

Highwall mining technology is the modified version of earlier auger mining. It facilitates recovery of locked up deposit in open pit highwalls, below villages, road, and other surface structures. Mining operations consist of driving series of parallel roadways at intervals in a planned way to recover considerable amount of coal from the highwall. The method offers great safety to mining personnel because of remotely controlled highly mechanised mining operations and unmanned extraction drivages. Although key to successful operations is scientific design of web pillars that support these drivages, optimum design to increase recovery is the main requirement. Design methodology includes estimation of long and narrow pillar strength through CIMFR empirical equation with some modification and application of numerical simulation to consider multi-seam interaction, pillar stress, etc. This methodology' has been utilised for highwall mine design at Opencast Project II (OCP-II) mine of Singareni Collieries Company Limited (SCCL) and Medapalli OCP (MOCP) of SCCL by CIMFR. Although, mining operations at both the sites are successful, performance analysis reveals that ooccurrence of roof fall, breakdown on account of geological disturbances and poor power supply, exposure of stone bands in the seam, working in cross gradient, etc., are some of the issues that has jeopardised full production capacity of the CHM. The highwall mining design methodology and performance analysis at couple of sites are discussed in detail in this paper. [ABSTRACT FROM AUTHOR]

The article explores the environmental impact of the use of explosives. Topics discussed include the important role of blasting in mineral extraction, important factors that need to consider when conducting blasting operations, and blast vibrations monitoring. A case study of the effects of seismic blasting in upper Assam in India is also discussed.

The article discusses the scientific investigations carried out by the Central Institute of Mining and Fuel Research (CIMFR) in Dhanbad, India to asses the stability of the proposed man-winding shaft due to nearby opencast blasting. It details the shaft of the Singareni Collieries Co. Ltd. (SCCL) located 250 meters away from the high wall of the RG OCP-II mine of SCCL. The article informs that the shaft lining has been made by taking into consideration of the tensile strength of concrete.