Hydrothermal leaching behavior of complex polymetallic secondary sulfide concentrate enhanced by ultrasonic

Complex polymetallic secondary sulfide concentrate (CPSSC) is difficult to efficiently be utilized because of its special mineral phase structure and high content of lead and iron. A novelty process proposed in this study, hydrothermal leaching without acid (water as lixiviate) enhanced by ultrasonic, can achieve eco-friendly and selective separation of copper from CPSSC, inhibiting production of hazardous material plumboferrite contained in leached residue. The influence of controlling parameters on the leaching efficiency and the mineral phase composition and structure of the obtained leached residue are studied. The obtained results show that, without sulfuric acid, the leaching efficiency of copper is the best under the conditions of temperature 180?C, oxygen partial pressure 1.0 MPa, stirring speed 600 r/min, ultrasonic power 360 W, liquid-solid ratio 10:1 and mass ratio of lignosulfonate to raw material 0.2%. Under the above optimal conditions, the leaching efficiency of copper and iron reached 99.12% and 19.46%, respectively. Ultrasonic enhancement increases the copper leaching efficiency by 10.02%, and promotes the leaching efficiency of iron decreases by 5.20%. The leaching process conforms the unreacted contraction core model under mixed control, the activation energy is 71.76 kJ/mol, and the macroscopic kinetic equation related to stirring rate, oxygen partial pressure and ultrasonic power is 1-(1-X)1/3 -1/3ln(1-X) = 40.457Po20.771?0.903P0.431e(-8630.19/T)t?