Atmospheric leaching of EAF dust with diluted sulphuric acid

Abstract

In this study the hydrometallurgical processing of EAF steelmaking dust (Paul Wurth S.A.) is investigated on a laboratory scale under normal temperature and pressure conditions. The behaviour of zinc and iron under the influence of sulphuric acid as the leaching agent is discussed. The dependency between the temperature and the liquid/solid ratio is investigated. The main aim is the transfer of zinc into the solution while iron ought to remain as a solid residue. The hydrometallurgical recovery of zinc from EAF dust is feasible with a relatively high recovery yield, while iron mostly remains in the solid phase. Calcium, too, is transferred to the solution with a relatively high recovery yield. This results from the use of a low concentration of sulphuric acid. In such a way, it is possible to set up the conditions for the leaching of EAF dust, namely sufficient sulphuric acid concentration in order to achieve an optimum zinc yield to the solution without an iron dissolution. However, the problem is that the chemical and mineralogical composition of each steelmaking dust is individual. Therefore, it is necessary to study the processing conditions for each one of them.