The use of fly ASH and portland cement to chemically fix metal mine drainage treatment sludges

摘要

The conventional treatment of metal mine drainages produces a sludge consisting principally of metal hydroxides and oxides. The volume of these sludges can be substantial, commonly ranging from 5 percent to 10 percent of the volume of mine drainage treated. Sludge volumes of 33 percent of the treated water volume have been reported~1. In addition, mine drainage treatment sludges are pH-sensitive. Exposure to even mildly acidic environments can cause the solid-phase metal hydroxides and oxides to dissolve and mobilize metals. Figure 1 illustrates the Ph-phase relationship of several metals commonly found in metal mine drainages. High volumes and chemical instability make mine drainage sludge disposal a challenging engineering problem and an expensive component of mine drainage treatment.