Pressure Leaching Of White Metal As An Alternative To Conversion

In the processing of copper concentrates by the conventional smelting-converting technology, complying with the increasingly severity of environmental legislation in some countries has become difficult, mainly due to severe fugitive emissions of gases produced during the batch PS (Peirce-Smith) converting step. In this work, the results of an investigation on the pressure leaching with sulfuric acid and oxygen of white metal (produced in a Teniente Converter reactor) are discussed. The study was carried out at laboratory scale and the main variables studied were temperature, concentration of sulfuric acid and partial pressure of oxygen. The experimental results indicated that most of the sulfur in the white metal was oxidized to sulfate in the whole range of temperature studied (105ºC to 150 ºC). The concentration of sulfuric acid over 0.05 M, and oxygen partial pressure over 6 atm had little effect on the dissolution of copper from the white metal. On the other hand, temperature had the most significant effect on copper dissolution; below 130 ºC copper dissolution was incomplete after 5 hours of leaching while at 150 ºC the dissolution was complete in 90 minutes and 10 atm of partial pressure of oxygen