Gold extraction by chlorination using a pyrometallurgical process

The feasibility to recover the gold present in alluvial material, by means of a chlorination process, using chlorine as a reactive agent, has been studied. The influence of temperature and reaction time was studied through changes in the reactant solid. The techniques used to characterize the mineral samples and the reaction residues were stereomicroscopy, X-ray diffraction, X-ray fluorescence and scanning electronic microscopy. Results indicate that gold extraction is favored by increasing, both, the temperature and the reaction time. The best recovery values were of 98.23% at 873 K and 3600 s and of 98.73% at 873 K and 5400 s, with very low attack of the matrix containing the metal. The powder of pure gold was not chlorinated at this temperature level.