Improvement of Copper Metal Leaching in Sulfuric Acid Solution by Simultaneous Use of Oxygen and Cupric Ions

Abstract

A new concept for copper (Cu) metal leaching by the simultaneous use of cupric ions (Cu2+) and oxygen (O2) was proposed to improve Cu metal leaching in sulfuric acid. According to this concept, Cu2+ oxidizes Cu metal into cuprous ion (Cu+), and O2 oxidizes Cu+ into Cu2+. The improvement in Cu leaching efficiency from Cu metal was investigated experimentally in the sulfuric acid solution using Cu2+ and O2 simultaneously. Furthermore, the result was compared with that for the sulfuric acid solution containing neither Cu2+ nor O2 and with the sulfuric acid solution without Cu2+ and O2. When both Cu2+ and O2 were used in the leaching solution, the leaching rate of Cu from Cu metal powder was higher than at other leaching conditions, and the leaching efficiency of Cu increased to more than 99.9% in 1 mol/L sulfuric acid solution at 400 rpm and 50 °C with ≤75 µm Cu metal powder, 1% pulp density, 10,000 mg/L initial Cu2+ concentration, and 100 cc/min O2 introduction. These results indicated that the leaching of Cu from Cu metal could be accelerated by adding Cu2+ and O2 in the sulfuric acid solution.