Reduction of leachability of heavy metals in acid mine drainage

Abstract

The leaching characteristics of sludges from the treatment of acid mine drainage(AMD) from Iron Mountain Mine near Redding, California were compared using two different processes: caustic soda treatment and a modified lime/sulfide treatment process. The modified lime/sulfide process produced a sludge with better dewaterability characteristics than sludge from the caustic soda process. The results of the Cal WET indicated that the modified lime/sulfide process sludge had less leachability than that of sludge from the caustic soda process. Both processes could achieve a substantial reduction of heavy metals in leachate to levels below the federal regulatory limits(TCLP). For cadmium and zinc, however, neither process produced a sludge that met the requirements of the Cal WET procedure.

Key words:

• Leachability
• Acid Mine Drainage
• Heavy Metals
• Dewaterability
• TCLP
• Cal WET
• High Density Sludge