煤炭取样 coal sampling

煤粉取样装置 coal powder sampler

煤层煤样采取方法 Sampling of coal seams ; Sampling of coal in seams

商品煤样采取方法 Sampling for commercial coal

煤层取样平面图 sampling plan of coal seam

生产煤样采取方法 Method of sampling run-of-mine coal

煤层的取样 Sampling from coal seams

煤粉取样装配 coal powder sampler