The kinetic behavior of Cr 2 O 3 reduction by iron melts containing carbon, aluminum and silicon were investigated at various conditions in order to understand effective slag treatment for recovery of chromium from stainless slag. It was found that the recovery rate of chromium was fairly slow, but it was considerably accelerated by the addition of some fluxes, such as Al 2 O 3 and SiO 2 to the slag, which promoted the formation of liquid slag at the early stage of the reaction, and the recovery ratio of chromium was also improved. In addition, SiO 2 addition was more effective for increasing the chromium recovery than Al 2 O 3 addition due to the effect of CaO/SiO 2 ratio of slag on the reduction rate of Cr 2 O 3 in slag. The experimental results were well simulated by the previous kinetic reaction model based on two-film theory. The modeling study showed that the transfer rate of chromium from slag to metal was controlled by the mass transport in the slag phase.
In order to understand effective conditions to recover chromium from stainless steel-making slags, the kinetic behavior of Cr 2 O 3 reduction by iron-carbon melts were investigated at various conditions by using solid Cr 2 O 3 powder and Cr 2 O 3 -CaO-SiO 2 -Al 2 O 3 -CaF 2 slags. The effect of temperature on the reduction rate of solid Cr 2 O 3 was fairly large and the apparent activation energy was about 180 kJ mol
Ϫ1. The overall reduction of solid Cr 2 O 3 was considered to be controlled by a chemical reaction step. For reduction of Cr 2 O 3 in slag, the addition of CaF 2 to slag and of silicon to iron melt promoted the reduction rate, but the reduction of Cr 2 O 3 powder was retarded by the silicon addition. The kinetic behavior of reduction of Cr 2 O 3 in slag could be well simulated by the kinetic reaction model proposed previously. As a result, it was found that the overall reduction rate of Cr 2 O 3 in slag was controlled by the mass transport in the slag phase.
An efficient continuous desiliconization process equipped with a mechanical stirrer in a hot metal runner was newly developed. The facility was installed during the revamping of No.3 blast furnace at Kobe Works, and the commercial operation started up successfully in January 2008. Before the installation of the commercial facility, the reaction behaviour was investigated under various experimental conditions for the application of a mechanical stirring method to continuous desiliconization treatment in the hot metal runner. Hot metal experiments at laboratory scale showed that the stirring intensity was an important factor for the process performance, and the mechanical stirring method was available for the improvement of reaction efficiency. As a result of plant tests, it was confirmed that a higher oxygen efficiency of desiliconization was achieved by the combination of runner arrangement and mechanical stirrer compared with the conventional injection of the desiliconizing agent. According to the reaction analysis of continuous desiliconization in the hot metal runner using the semi‐batch reaction model, it was estimated that the average slag‐metal residence time in the reaction region is improved due to an increased entrainment of foamed slag into the stirred metal bath in the mechanical stirring method, and therefore, it leads to a high desiliconization efficiency. Based on the experimental results, the equipment specifications and the runner design for this process were determined.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.