Evaluation of Arsenic bioavailability in waste from cyanidation Gold Processing using sequential extraction schemes (SES)

Non-free Gold ores is frequently associated with minerals rich in Arsenic, such as arsenopyrite. The waste from Gold mining processing from the flotation and cynidation stages. The dams are a potentially source of environmental contamination, because many hazard elements are present, especially Arsenic. The study of characterization is essential, once that many natural processes can interfere at the stability and mobility of these elements. Sequential Extraction Schemes (SES) is a method where it is possible to evaluate the characteristic of bioavailability which the element of interest is associated. Marin SES1 uses reagents to extract transition metals from four phases, classified from the easiest, available with just an exchange of pH, named Exchangeable, until the metals associated with the crystal structure, named residual. This research studied the waste from Cyanidation process in order to evaluate Arsenic forms potentially available to the environment. Marin SES evaluated the amount of each one of the schemes. The extractions were analyzed by Inductive Couple Plasma Optical Emission Spectrometry (ICP-OES) technique (Table 1), the average total digestion concentration for As is 413 ± 4 mg Kg-1. The sum from fractions was 405 ± 15 mg Kg-1. The Arsenic was released in the order residual>organic matter>bound to Fe/Mn oxides>exchangeable (Figure 1). This result shows that Arsenic is a potential source of contamination from this tailing sample.