Back — The roof or upper part in any underground mining cavity. Backfill — Mine waste or rock used to support the roof after coal removal. Barren — Said of rock or vein material containing no minerals of value, and of strata without coal, or containing coal in seams too thin to be workable.
A. Abutment - In coal mining, (1) the weight of the rocks above a narrow roadway is transferred to the solid coal along the sides, which act as abutments of the arch of strata spanning the roadway; and (2) the weight of the rocks over a longwall face is transferred to the front abutment, that is, the solid coal ahead of the face and the back abutment, that is, the settled packs behind the face.
The Raymond mill is used to grind materials in the fields of building materials, mining, metallurgy and chemical industry. The materials must be non-flammable and non-explosive materials such as: limestone, calcite, barite, dolomite, potassium feldspar, marble, talcum, gypsum, kaoline, medical stone, rock phosphate, manganese ore, iron ore, glass, ceram, active carbon, carbon black, fireproof ...
Gravel - Wikipedia. Gravel /ˈɡrævəl/ is composed of unconsolidated rock fragments that have a general particle Crushed stone: rock crushed and graded by screens and then mixed to a Also known as "crusher run", DGA (Dense Grade Aggregate) QP (Quarry In locales where gravelly soil is predominant, plant life is generally more
[2008-10-14]1.2015 professional china unique industrial 100tph mobile crusher for sale [2008-12-03]dustrial mobile crushing plant with competitive price [2009-01-22]3.new improved industrial best sand making machine mobile stone crusher for aggregate for sale