| Popis: |
The role of sulphide minerals in the process of Ag reprecipitation during the supergene alteration of polymetallic ores has been evaluated using the databases WATEQ4F (Ball and Nordstron,1991) and SUPCRT'92 (Johnson et al., 1992). Four common principle oxidation stage were fixed previously with formation of the following Agproducts, when oxygen fugacity decreases: (1) cerargyrite AgCl(s) below the residual ore zone at lg f% atm 10 97Stool/l; (2) Ag(s) in the upper part of the zone of oxidation. Corresponding to the differences in Eh-pH regimes, the Ag § activity can vary within the limits: lg jo_~,atm pH lgaAg,,mol/1 30 --40 3 --3.23 --5.73 --40 --50 4 --6.73 --9.23 |
