Experimental study on high basicity lime fine powder fast-melting refining slag

High basicity can improve the distribution ratio of sulfur and phosphorus of refining slag, and therefore improve the efficiency of sulfur and phosphorus removal. However, high basicity can also increase the melting point of refining slag, resulting that the melting rate of refining slag becomes slow, which extends the time of secondary refining. Calcium aluminate premelting slag has a low melting point and high melting speed, but the premelting productions needs high energy consumption, and besides the A12O3 content is high, so the basicity is low. With the combination of lime fine powder and flux, melting speed can be increased and meanwhile low energy consumption and high basicity can be obtained comparing with premelting slag. In order to solve the problem that lime fine powder is easily to be hydrochemical metamorphism that affects its application, it is employed in this paper that the methods of physical deactivation and heating melt or alcohol dissolution to dissolve out cladding to dispose the lime fine powder. The results show that 4% of stearic acid has a relatively good passivation effect under ethanol dissolution cladding treatment process, which can make the passivating lime fine powder samples store for a week and its hydration rate was only 16%. In addition, the effect of slag granularity on the melting rate of slag is also analyzed by experiments, and the results show that when the particle size of slag is at around 200 mesh, its melting rate tends to reach a limit. This provides a guideline for the application of high basicity lime fine powder to refine refining slag.