Study of the technology for raw coal in-depth destoning under the condition of combined mining of contiguous seams

In order to rationalize and optimize the technological process for washing the raw coal produced by mining of contiguous seams using combined mining method in Wuhai mining area, and increase the recovery of coal resource, four kinds of equipment that can be used for preremoval of dirts in this case are compared and analyzed from both technical and economic aspects:movable-bed jig, heavy medium vessel, TDS intelligent dry separator and compound double-entry air chamber jig. It is demonstrated that the compound double-entry air chamber jig can remove 43.20% of the dirts and the ash of the rejects is as high as 80.75%. Comparatively, the use of the jig offers the merits of being capable of effectively getting the finer dirts removed with lower operating costs. Furthermore, its use for in-depth preremoval of dirts from raw coal can reduce the volume of raw coal for treating by primary washing system and weaken the adverse effect produced by mining dirt that is prone to undergo degradation in water. And it's use can yield noticeably favorable economic result. The study made in the paper may serve as a guidance for in-depth raw coal deshaling under similar mining conditions in other mining areas.