Characterization of arsenical mud from effluent treatment of Au concentration plants, Minas Gerais – Brazil

Abstract

The determination of the general properties of arsenical mud was carried out in effluent treatment plant of an Au metallurgical facility, located in Nova Lima, Minas Gerais, Brazil. This effluent, which comes from the calcination stage, is treated via Fe-coprecipitation / lime-neutralization and thus mud with high As concentration is generated. Instrumental methods were applied to investigate physical-chemical characteristics, such as pH, in addition to the forms of occurrence of As and its associations. The results indicated that the mud has an alkaline pH (≈ 8.5), particles with grain size below 20 µm, and As, Fe, S and Al concentrations above 5%. The element As is essentially associated with Fe, Ca, S, and Al, forming phases with wide compositional variation as major and minor constituents generically classified as “complex sulfates” and “compounds with S”. The obtained results could assist optimization of the treatment routes in the plant and even to consider the potential reuse of this arsenic mud as a potential valuable product.