Environmental Mineralogical and Hydrogeochemical Studing of Coal Tailing in Zirab Coal Cleaning Factory, Mazandran Province

Nowadays، environmental minerals represent one of the most important problems in coal mine and coal cleaning factory contamination. Zirab coal cleaning factory in Mazandaran Province is one of the largest and the oldest in the coal concentration of the Central Alborz Coal Basin. So، annually، a huge amount of coal tailing will be left. The sampling of environmental secondary surface minerals، drainage water from coal tailing،the factory''s waste water، and river water have been carried out. Hydrogeochemical studies demonstrate that drainage and seepage water from tail dumps are of the (Na-Ca-Mg) -SO4 type. Gibbs diagram indicates that lithology is the most important factor in increasing the ionic concentration in drained and seepage water from tailing and river water. In arid seasons due to the evaporation of hydro-sulfate solution، blodite and secondary minerals are formed on the tailing dump surfaces. This drainage water from tailing and Zirab coal cleaning factory into the adjacent river has caused the precipitation of hematite، calcite and amorphous iron oxide. Hydrogeochemical modeling has shown that hematite goethite and iron hydroxides along with carbonate minerals (calcite، dolomite and aragonite) are present. The rate of SO4، PO4، Ca، Sr، Sb، and Bi in seepage water from tailing and coal cleaning factory are higher than the standard values، which can cause both surface and groundwater pollution in this region.