Mine Tailings Treatment
Zeolite provides a simple solution to the complex issue concerning mine tailings. Simple science using zeolite can reduce and eliminate these concerns. Zeolites are low cost ion-exchangers for the removal and recovery of heavy metals cations, particularly in acid mine drainage. They are used in four ways in order to treat heavy metals and mine waste:
1) Removal of metal cations in effluent/wastewater by Direct Filtration. Zeocan Zeolite has a very high CEC as compared to other zeolites and will trap and hold the various metal ions (see the list below). Significant properties include: -High cation exchange capacity -Selectivity for many metals -Low cost relative to resins or synthetic zeolites -Capacity for regeneration 2) Soil remediation by Stabilization. This involves the application of zeolite directly into the contaminated soil in order to chemically bind the metal ions via cation exchange. (Refer to Stabilization Menu in the Oilfield Section). 3) Soil remediation by Encapsulation. This involves a process of mixing the mine waste with water, zeolite, and cement in order to create a concrete block that passes TCLP1311 Leachability Testing. Currently, there are many environmental companies using this method to handle oilfield drilling waste. (Refer to the Encapsulation Menu in the Oilfield Section). 4) Soil reclamation. Zeolite is an excellent Soil Conditioner as it holds fertilizer and makes it available year round by preventing leaching into the environment. In many cases the zeolite amended soil reclamation program outperforms the control plots prior to the mining activity. (Refer to the Soil Conditioner Menu in the Agriculture Section). 5) Removal of heavy metals from industrial and mine drainage, currently achieved by direct addition of lime or soda, may be done in the future by zeolite. Heavy metal removal, particularly in acid mine drainage, has potential for a growing market.
These are some of the metal cations that zeolite can trap: Ag (Silver) Co (Cobalt) Mn (Manganese) Al (Aluminum) Cs (Cesium) Mg (Magnesium As (Arsenic) Cu (Copper) Mo (Molybdenum) Cd (Cadmium) Fe (Iron) Ni (Nickel) Cr (Chromium) Hg (Mercury) Pb (Lead) Sr (Strontium) Ur (Uranium) Zn (Zinc)
The recovery of some metals can be as high as 97% removal. Once bonded to the zeolite matrix it is very difficult to break as they are trapped with cation exchange. The other metals like As, U, Cr, Mo may be immobilized by hydrogen bonding of oxyanions. Salts, Na, is also bound up by the zeolite. Zeolite is able to greatly reduce the alkalinity effects in soil.