STUDY OF ACID MINE DRAINAGE AND ITS NEUTRALIZATION FOR THE AREA OF THE ABANDONED MINE

The study of Acid mine drainage (AMD) formed in the area of the abandoned mine. The neutralization method for the AMD was developed, under which the processes occurring in AMD with increasing pH by Na2CO3 were studied. It was shown that after increasing the pH to 6.0, a slight decrease in pH values is observed. Along with a decrease in pH, an increase in water turbidity is also observed. The decrease in pH and increase in turbidity can be explained that the precipitation of schwertmannite (to pH 4.5-5.0) is caused by the transition of divalent iron to ferric iron, which consumes an additional amount of alkali, which leads to a decrease in pH. When metals are deposited from AMD using Na2CO3, two mechanisms appear to be at work. The first is based on the formation of carbonates of individual metals. The second is the formation of hydroxides due to an increase in pH. Apparently, these two mechanisms are competitive and in such a complex system it is difficult to assess which of these mechanisms prevails. Thus, the suggested AMD neutralization method can be used to improve water quality of the rivers which flow crossing the mining areas.