Experimental Study on Deep Desulfurizer in LF Process

CaO-Al2O3-SiO2-CaF2-MgO was selected as the slag system for desulfurization in LF process. The reaction between steel and slag during desulfurization has been simulated by using Factsage software to study the influence of component on the sulfur distribution ratio. In order to research the influence of CaO content, aluminum powder content and its granularity on desulfurization, laboratory experiments have been carried out in a 200 kg inductive furnace. Results showed that the optimal composition of deep desulfurizer is wCaO = 64% and aluminium powder 10% with a granularity of 30 μm. Industrial trials showed that the main composition range of final slag in LF process is wCaO = 53.0%–57.0%, wAl2O3 = 23.4%–25.1%, wSiO2 = 8.1% – 10.0%, and wCaF2 = 3.2%–4.7%. The sulfur mass percent in steel is lower than 0.0008% with a desulfurization rate above 89%. According to the result of industrial production, this desulfurizer could meet the production requirement for ultra-low sulfur steel, of which sulfur mass percent is under 0.0015%.