Fundamental Research Of Reducing Dephosphorization On Silicon-manganese Alloy With High Phosphorus

In recent years, Steel industry is developing rapidly in China, the corresponding manganese-based alloys industry also develops rapidly and the manganese-based alloy production of China becomes the first in the world. However, China’s manganese-based alloy industry still is a low concentration ratio, backward technology and equipment, high energy consumption, low-quality products and high impurity elements contained. Meanwhile, because of the low grade ore, China always depend on the high-grade manganese ore imported, which lead to high production cost. In this case, the manganese-based alloys industry urgently needs to improve.The manganese ore resources is abundant in china, however, the average manganese grade is less than 30%, and the manganese ore contains high impurity content, especially in Chengkou and Xiushan area, the ore contains high phosphorus and sulfur content. When the manganese alloy was smelted to produce silicon-manganese alloy directly, the phosphorus content in the alloy would be exceed seriously, and silicon-manganese alloy is usually used as a compound deoxidizer and alloying agent in steelmaking, so the phosphorus contained in the alloy would be dissolved into the steel liquid, which is causing the steel "cold crisp" and reduces steel quality. Therefore, controlling manganese alloy`s phosphorus content is the subject of the study.In this paper, dephosphorization of silicon-manganese alloy with high phosphorus is been studied under reducing atmosphere in silicon molybdenum furnace, the influence of temperature, smelting time, the amount of Ca Si, the initial silicon content, the rate of Ca O in Ca O-Ca F2 slag and other factors on the dephosphorizing rate are investigated, and the element contents in silicon-manganese alloy is analyzed using ICP spectrometer and chemical analyses, and conclusions are listed as following:① Low temperature was conducive for dephosphorization, but the reaction kinetics condition deteriorates if the temperature is too low, so the best temperature range is between 1400 ℃ to 1420 ℃.② Prolonged processing time is not conducive to dephosphorization, the best processing time was the time when the dephosphorizer just completely dissolved.③ The dephosphorization rate is increasing with dephosphorization agent. The dephosphorizing rate is up to about 76% when dephosphorizing agent is 19 wt.% of alloys, and the alloy`s phosphorus content was 0.25 wt.% which is reaching the national standard value.④ A certain amount of Ca C2 added can inhibit the reaction of Ca and carbon under high temperature, reduce the loss of Ca, it is conducive for dephosphorization, but the Ca C2 has a poor dephosphorization capacity.⑤ Alloy dephosphorization rate is increasing with silicon content, when the silicon content in the alloy is larger than 20%, the dephosphorization rate increases significantly.⑥ It is conducive for dephosphorization by increasing the content of Ca O in covering slag, when the temperature was 1420 ℃, the best Ca O content is 19mol%.