NaClを含むHNO<SUB>3</SUB>水溶液中における銅アノードスライムの浸出挙動

Abstract

The acid leaching for copper anode slime in dilute acid solutions and the oxidative leaching behavior of the acid leach residue sample in a nitric acid solution containing sodium chloride have been investigated from both a thermodynamic consideration and an experimental study based on the results obtained on the leaching rates, the stoichiometry of the leaching reaction and the X-ray diffraction analysis of the leaching products. The main results obtained are summarized as follows:(1) The pre-treatment of Cu-anode slime by using an acid leaching technique is effective, and the precious metals such as Au, Ag and Pt remain in the acid leach residue. However, Cu and Pb are easily dissolved under the acidic conditions, and this tendency coincides with thermodynamic considerations.(2) The oxidative leaching for the acid leach residue of Cu-anode slime in a nitric acid solution containing sodium chloride is fast, and the leaching rate increase with an increase in the concentractions of sodium chloride and nitric acid in the leaching solution. The precious metals such as Au, Pt and Pd are dissolved into the leaching solution. However, Ag remains as AgCl in the oxidative leach residue.(3) From the experimental results obtained, the optimum leaching conditions are as follows. The concentrations of sodium chloride and nitric acid in the leaching solution are 2 kmol/m3 and 1 kmol/m3, respectively, and the mass of the acid leach residue sample is below 10 kg.