Abstract
Retreat longwall mining is the most productive system for underground extraction of tabulated deposits. However, the steady growth of the mining depth dramatically increased the ground pressure in chain pillars protecting the longwall entries. Therefore, several coal industries have tried to shift to pillarless mining and practiced maintenance of the head or tail entry behind the longwall in the stress relief zones using the backfill bodies in the thin coal seams. We modernized the pillarless variant of the retreat longwall system introducing the third roadway, which is driven in the consolidated goaf behind the moving longwall in a stress relief zone. We used a computer code FLAC3D to simulate stress redistribution during pillarless extraction of adjacent panels that assisted to determine optimal parameters of mining layout. This modernized technology provides for sustainable mining due to enhancement of transport, ventilation, safety conditions, and a comfortable environment because of the stability of the underground roadways, which serve the high productive longwalls.
Highlights
Shallow reserves of energy resources have depleted since the middle of the twentieth century
An economic assessment has demonstrated that extra cost of the third roadway driven in the goaf does not exceed 10% of the total profit from the increase of the coal output due to enhancement of transport, ventilation, safety conditions, and comfortable environment because of stability of the underground roadways serving the high productive longwalls
Retreat longwall mining using the chain pillars has become popular in underground mining since the 1960th
Summary
Shallow reserves of energy resources have depleted since the middle of the twentieth century. The depth of mining has increased steadily that was followed by the intensifying of the ground pressure. The growing ground pressure augmented the problem of the underground roadway maintenance deteriorating its stability radically [1]. The underground roadways present the main part of the underground mine fixed assets Their deterioration dramatically inflates the total cost of extracted mineral resources. The task of maintaining the underground roadways’ stability at the great depth has become a challenge. The purpose of this presentation is to develop a prospective longwall technology using the maintenance of the roadways in the stress relief (SR) zones. We outlined the methods for the investigation of ground pressure redistribution during the pillarless panel extraction. The advantages of the new system have been discussed and the main conclusions outlined
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