Improving the processing of steelmaking waste. Part 2. Development of the basic processing system

Abstract

The expediency of reducing steelmaking slags to obtain metallic and oxide phases for use in metallurgy and construction is studied experimentally. Slag from the tailings at Zlatoust Metallurgical Plant is investigated. Experiments are conducted on the reduction of slag samples by carbon. The composition of the experimental samples is determined by X-ray spectral microanalysis. Experimental and theoretical data indicate that 20% (or even more) of the initial slag mass may be converted to metal by reduction. Practically complete reduction of the iron in the slag is possible. Significant proportions of the chromium, nickel, manganese, and other valuable components may pass to the metallic phase. Reduction of the liquid slag is expedient at 1500°C or more, so as to extract the metals more completely and form a consolidated metal phase. Preliminary solid-phase reduction of the slag at 1100–1200°C is found to be expedient. This process converts much of the iron present as oxides in the slag to a form susceptible to magnetic separation. Subsequent magnetic separation allows the fraction with an elevated content of valuable metals to be extracted from the oxide phase, which has a low metal content. The oxide fraction may be used in construction materials. In the design of systems based on these principles, utilization of the large quantities of carbon monoxide and metal vapor in the gas phase is recommended. One possibility is to use the carbon monoxide for preliminary solid-phase reduction of the slag. This research permits the development of an efficient system for processing slag tailings.