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.
Surface mining is defined as the extraction of ore from an open pit or burrow. Surface mining is sometimes known as open-pit, open-cut or open-cast mining and is only commercially viable if the deposit is located relative close to the surface. Less than 20% of Alberta's bitumen reserves
A group of northeast Iowans effectively is keeping large frac sand mine companies from mining silica-rich sand in their county by building a consortium that set aside politics and focused on dealing with the matter locally, instead of with state intervention.
To get a look at the oil sand mines we rented this Cessna 172 which the pilot was allowed to bring down to 1,000 feet — from there, through the open window and with a long lens we were able to see what really goes on in one of the most controversial places on the planet
K Series Mobile Crushing Plant. Based on more than 30 years' manufacture experience, millions of equipment units' installation experience and abundant invested in research and development, SBM has released the K series portable crushing and screening plants