Principal processing flowsheet of copper–brass wastes of metallurgical brass production

Abstract

The process flowsheet of dusty wastes forming during metallurgical brass production with the use of two-stage leaching is proposed. The production solution, which contains the main amount of zinc ions (0.46 mol/L) and a small amount of copper ions (less than 0.02 mol/L) is formed at the first stage during the dust dissolution with the 0.5 mol/L sulfuric acid solution. Copper and zinc are sequentially electrochemically isolated from this solution at the current density of 0.1 A/dm2 and 5.0 A/dm2, respectively. A dry residue (cake) is subjected to copper–ammonia leaching, due to which copper completely transfers into the solution, while accompanying metals remain undissolved. To recover copper from the formed solution, liquid extraction with the solution of 0.34 mol/L DX-510A in kerosene is applied. Copper ions are recovered from the organic phase by reextraction with the 2.0 mol/L sulfuric acid solution. Cathodic copper is isolated from the sulfuric acid electrolyte at the current density of 1.5–2.0 A/dm2. The advantages of the proposed flowsheet are an increase in environmental safety due to the use of recirculation of solutions at all process stages, as well as minimization of wastes of the whole process of processing of dusty metallurgical slime.