Importance

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Abstract

In the mining of various minerals from the earth, large mining shafts extending from the surface down to the deposited mineral layers or seams in the earth can be provided through the use of large diameter bore hole drilling equipment. With the drilling equipment stationed on the surface of the earth, a drilling member is drilled down into the earth for forming a shaft in excess of 10 feet to a depth of at least 2000 feet. As the earth is broken up during the drilling operation, the broken fragments are removed from the drilled hole by a reverse circulation drilling operation. During the drilling operation, the drilling bit is maintained in proper alignment with the shaft being drilled by the use of non-rotating stabilizers having an outer diameter substantially equal to the diameter of the hole being drilled. By maintaining fluid at a sufficient level in the drilled hole during the drilling operation, an adequate hydrostatic head can be created for exerting an opposing pressure on any zone of instability on the walls of the drilled hole for preventing inflow of water and debris.

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First Claim