KINETIC DISCUSSION ON DEOXIDATION AND DESULPHURIZATION OF MOLTEN STEEL WITH CALCIUM TREATMENT

摘要

Based on kinetic researches of deoxidation and desulfurization with calcium treatment for molten steel, it is found that when solid calcium particles are fed into molten steel, some dissolve and the others become calcium bubbles reacting with oxygen and sulfur. The bigger the diameter of calcium particle is, the bigger the residence time and average flotation speed of the calcium bubble in molten steel are, and the less the mass transfer coefficients of deoxidation and desulfurization are. The residence time and flotation speed have hardly relationship with temperature in the range of steelmaking temperature, but the mass transfer coefficients become big with increasing temperature. When oxygen and sulfur contents increase, the optimum diameter of calcium particle increases. The utilization rate of calcium decreases with increasing particle size at a given depth of molten steel and given contents of oxygen and sulfur. Calcium particle with its diameter less than 0.002 m will be wholly utilized at the temperature T = 1823 K, the mass content of sulphur in molten steel w[S] = 0.012 % and the height of molten bath H=3m. The utilization rate is 84.4 % when particle diameter is in the range of 0.002～0.003 m.