Method of mining heavy coal seams in two or more benches

Mining or in situ disintegration of hard material – Processes – Stabilizing underground structure

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405267, E21C 4100, E21F 1500

Patent

active

043402542

ABSTRACT:
In mining a heavy coal seam that must be excavated in several benches, the excavation of the uppermost bench is accompanied by the introduction of a cementitious slurry into the resulting stope for consolidating the waste rock present therein, preparatorily to the excavation of the next-lower bench, and proceeding in like manner with the second bench if a third one is to follow. The cementitious slurry comprises burnt or slaked lime, and/or portland cement, suspended in water in a quantity of about 10 to 60% by weight and preferably together with a small percentage of chlorides of one or more alkali or alkaline-earth metals, to which ceramic aggregates at large specific surface such as mineral ashes, slag, sand or dolomite powder may be added in a quantity of up to about 30% of the weight of the water. The slurry, on being admitted to the stope in an amount of at least 10% of the volume thereof, causes the waste rock to swell and to form a solid layer of up to approximately a meter in thickness which allows the next-lower bench to be excavated after only about a month's delay.

REFERENCES:
patent: 1233301 (1917-07-01), Bartlett
patent: 4059963 (1977-11-01), Wayment
patent: 4198097 (1980-04-01), Fondriest

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