Modeling the Composition of Mine (Waste Rock) Water at the Deposits of the Balkhach Gold-Bearing Field

摘要

Modeling of hydrogeochemical processes in the rock—water system showed that the concentrations of Al, Fe, Sb, Sr, and W do not exceed the MAC levels even under conditions of prolonged interaction between water and rock minerals (R/W> 0.0001). The concentrations of As, Cd, Co, and Se are unlikely to significantly exceed the MAC even at decreasing rates of water exchange (at increasing R/W) owing to the low concentrations of these elements in the rocks of the deposit. The concentrations of Mn are likely to exceed the MAC level under reducing conditions, while they remain well within the MAC under weakly to moderately oxidizing conditions. A different situation is for Cr and S, which may be well above the MAC under oxidizing conditions and below the MAC under reducing conditions, when weakly oxidized species of S and Cr predominate. Model and measured concentrations of Cu, Mo, Ni, Pb, V, and Zn are generally similar to each other and to the MAC levels, but they may considerably exceed the MAC in the case of reduction in water exchange rates (longer duration of water—rock interaction and higher R/W). The concentrations of Cu, Mo, Ni, Pb, V, Zn, and Cr may exceed the MAC levels in the case of the prolonged exposure of strongly disintegrated rocks to moist air, whereas the wet environment is favorable for Mn hydroxide precipitation.