Sustainable recycling of residues of nickel production in EAF steelmaking route

A stock of over 100 Mt of residues (colas) from metallurgical production of nickel exists presently in Cuba with concentrations around 0.4%Ni, 42%Fe and 2.0%Cr. The annual production of colas in year 2005 will be about 10 Mt/year. The aim of this study is to develop a sustainable recycling concept in EAF steelmaking route for utilising a part of these residues, thus reducing impact on the environment and recycling valuable materials. Experiments have been carried out in suitably equipped 50 kg lab-scale electric induction furnace adding, inserting or injecting of tailings at 1600°C with or without reducing agents (e.g. anthracite) to study recovery of the metals contained to the steel melt under equilibrium, quasi-equilibrium and non-equilibrium conditions. Thermodynamical calculations at RWTH had shown nearly complete reducibility of the compounds NiO and Cr₂O₃ from the colas. The experiments reported in this study have confirmed this, resulting in about 90% recovery of Ni, 80%of Cr and 99% of Fe.