Recuperación de oro a partir de tarjetas de circuitos impresos de aparatos eléctricos y electrónicos descartados con tiosulfato de sodio como agente lixiviante.

Abstract

The objective of this work is to recover gold with sodium thiosulfate, which is an eco-friendly leaching agent that can improve the dissolution kinetics of precious metals compared to cyanide, because the generation of waste electrical and electronic equipment is imminent , due to the increasing technological advance and excessive increase in the production thereof, therefore, recycling is proposed as they are a source of base metals and precious metals such as gold and silver waiting to be extracted. In the first instance, a preliminary conditioning treatment of the material was carried out: crushing, oxidation roasting, pulverization and copper removal using nitric acid reaching a 93% dissolution. The leaching of gold was carried out at room temperature with 5% solids and a 0.7 M Na2S2O3 solution, using NH3 to adjust the pH to 10.5 for 6 hours and stirring speed of 700 rpm, allowing dissolution of 85% gold. Subsequently, the adsorption process was evaluated with the Purogold MTA5011 resin, it being possible to adsorb 87% gold using a resin: leach ratio of 100 g / L for 24 hours at room temperature. Then, the elution process was carried out in two stages, the first one allows 83% of copper to be eluted with an ammoniacal sodium thiosulfate solution, and the second allows the elution of gold with potassium thiocyanate reaching 98% recovery. Finally, it was made the electrowinning process, applying a current of 0.5 V to the solution resulting from the elution, for 6 hours at pH 12 and room temperature, reaching a recovery of 62% gold.