Immobilization of arsenic and iron from acid drainage waters by using reagent

Abstract

In the paper the precipitation of arsenic and iron from an acid drainage water of the Berikul mine wastes by using lime milk, NaOH, and Na2S were studied. The wastes were stored in the southern part of the Komsomolsk tailings impoundment, near the Komsomolsk settlement (Kemerovo region, Russia). The interaction of natural waters with the wastes produced ultra-acid drainage with a pH of about 2, with arsenic content of 1.3 g/l and iron-6.5 g/l. The results of in situ experiments showed that adding lime milk and sodium hydroxide to drainage increases pH and entails precipitation of iron hydroxides and co-precipitated arsenic. The adding of Na2S changes Eh of the solution and recovers of arsenic and iron. In the mineralogical composition of the newly formed mineral phases gypsum, sulfur, kaatialaite, arsenosiderite Ca3Fe4(AsO4)(OH)6×3H2O, were found. The study was set the most optimal ratio of reagents by which the arsenic concentration decreased to 0.11 mg/L and iron up to 3.0 mg/L.