METHOD OF OPEN-UNDERGROUND EXTRACTION OF COAL PILLARS LEFT BETWEEN MINE-FILED BOUNDARY AND PIT WALL

摘要

FIELD: mining. ^ SUBSTANCE: method includes extracting coal pillars by conducting shrink stoping from pit wall to mine-field boundary and leaving supporting coal pillars between shrink stoping. A coal pillar is divided into blocks; supporting coal pillars are left between the blocks so that the width of each exceeds the maximum width of a pillar and when it is reduced, destruction of pillar by rock pressure occurs. The length of shrink stoping is defined according to the mathematical expression. ^ EFFECT: higher stiffness of shrink stoping and labour efficiency of conducting thereof. ^ 3 cl, 3 dwg