Tratamiento químico y biológico de efluentes mineros cianurados a escala laboratorio

Abstract

Cyanide is a chemical compound used per excellence for gold leaching in the mining industry. However, it is highly toxic for the environment and its organisms. This work focused on determining the optimum conditions for the degradation of CN- using chemical compounds and a microbial consortium. Chemical and biological assays were performed separately using samples of mining effluents at different cyanide concentrations (280 and 10 mg/L CN-). For chemical degradation, three different oxidizing compounds were used: sodium hypochlorite, Caro’s acid and hydrogen peroxide at different concentrations, pH (10-11), and degradation times (4.71 and 20.75 h.). For the biodegradation assays, a microbial consortium was cultivated in flasks containing the cyanide effluent, liquid medium, pH (11), agitation (200 rpm) and temperature (20±5°C). Free cyanide concentration, pH and the biomass concentration were measured. Chemical treatment results showed that the best oxidizing compound was hydrogen peroxide (8:1 g H2O2 / g CN-) and pH (10), thus obtaining a 92.73% removal of free cyanide in 45 minutes (280 mg/L CN-) and 91.01% removal in 25 minutes (10 mg/L CN-). While in biodegradation the removal was 73.68% (280 mg/L CN-) in 384 h and 78.57% (10 mg/L CN-) in 240 h.