Electrorecovery of gold and silver from thiosulphate solutions

Abstract

The present invention is related to the mining industry and treatment of mineral and materials that contain gold and silver. Specifically, it is related to a process to recover gold and silver, from copper thiosulfate solutions with a autogenerated electrolysis process. The advantages of the present invention, relative to those of the state of the technique, reside in the increased velocity compared with cementation using copper, without employing electric current. Our process is characterized by operating in an electrochemical autogeneration cell, in which the anode and cathode are connected in short circuit and the anodic and cathodic compartments are separated by an ion exchange membrane. Additionally, using a copper anode and the stripped solution as the anolyte, the levels of soluble copper are maintained stable, conserving the leaching power of the thiosulfate solutions, whereby it is possible to recycle them back to the leaching stage.

1 .- 3 . (canceled) 
     
     
         4 . An autogenerated electrolysis cell for the electrorecovery of silver from thiosulfate leaching solutions comprising a cathodic and an anodic compartment separated by a ion exchange membrane, a copper anode and a titanium cathode, connected in short circuit, a catholyte consistent in a pregnant leaching solution and an anolyte, stripped of its gold and silver in the cathodic compartment. 
     
     
         5 . A silver electrorecovery process from thiosulfate leaching solutions, in an autogenerated electrolysis cell, consisting of the following: in the first stage, feed the cathodic compartment with a solution proceeding from the leaching step, feed to the anodic compartment a synthetic solution similar to the catholyte, but without dissolved silver, maintain the operation of the electrolysis cell during a specified time, mechanically recover the silver deposit by being performed in an autogenerated electrolysis cell as was stated in the previous claim; the predetermined time that the cell operates is that which permits the silver concentration in the catholyte and the copper concentration in the anolyte to achieve a predetermined level; successive stages follow the first, in which the anolyte is the catholyte after having been stripped of silver and the leaching solution is the anolyte after having been enriched with copper ions. 
     
     
         6 . The silver electrorecovery from thiosulfate leach solutions of  claim 5 , wherein the predetermined level of the copper concentration is adequate, on one hand, to maintain the potential difference necessary from 4 to 7 g/L of dissolved copper for the autogenerated electrodeposit and, on the other, for silver leaching.