Desulfurizing iron-carbon melts with lime under reduced pressures

Experiments were carried out to compare the rates of formation of CaS on CaO crystals which were either immersed in a sulfur-bearing, carbon-saturated iron melt or held in the effluent gases just above the melt. Temperatures ranged from 1375°C to 1600°C, and times ranged from one to twelve hours. The CaS layers were measured both metallo-graphically and with an electron microprobe. Data on the time and temperature dependence of the layer thickness are presented. These layers were about 15 microns thick after 6 h at 1460°C, independent of whether or not the crystal was immersed in molten iron. The role of lime in the desulfurization process is to act as a getter for removal of sulfur from the gas stream. W. C. PHELPS, JR., Deceased, formerly with the Department of Metallurgy and Materials Science, Purdue University, Lafayette, Ind. 47907.