Lab-scale Experiment and Industrial Test for Direct Alloying with the Ferrosilicon-MoO₃ Self-reducing Briquette

Abstract

Lab-scale experiment and industrial test for direct alloying with ferrosilicon-MoO₃ self-reducing briquette have been conducted. In order to avoid volatilization of MoO₃ during direct alloying, the high-temperature volatilization characteristics of MoO₃ has been studied, and it can inhibit the volatilization of MoO₃ when adding ~25% MgO during the heating. Furthermore, lab-scale direct alloying experiments with self-reducing briquette were carried out to determine the optimum composition of briquette to get high yield of Mo in a medium frequency induction furnace. The Mo yield was related to the excess reducing agent (ferrosilicon) and the right flux addition (MgO, CaF₂) inside the briquette. The results indicated that the amount of ferrosilicon maintaining the mixing molar ratio Si/O at 2 should be added. The flux addition must be controlled to form molten slag rapidly inside the self-reducing briquette. With the optimum composition of reducing agent and flux addition, the yield of Mo could reach as high as ~96%. When adding the self-reducing briquette into a 60 t ladle of Shijiazhuang Iron and Steel Co. Ltd. for industrial test, the average yield of Mo was 98.25%, and the change in the technology did not have an impact on the quality of products.