Anthracite mechanical-mining investigations. Use of yielding steel supports (props) in combination with backfilling for mining thick, flat beds

Successful tests of steel roof supports, used in place of conventional wooden timbers, in mining anthracite at Plymouth, Pa. are described. The yielding steel supports, called Becorit props, were imported from Germany, where they have been used for some time. At the same time, tests with a mechanical stower to fill in mined areas with rock and shale, thus minimizing subsidence of overlying strata, were arranged by the company.