Sulfur Species in Blast Furnace Slag and Their Mutual Relationships

Abstract

The sulfur species in some blast furnace slags were analyzed by means of the newly developed methods, and their mutual relationships were considered under various conditions (storage environment, standing time, particle size). Sulfide, thiosulfate and sulfite sulfur were determined by iodometric titrimetry, sulfate and total sulfur by chelatometric titrimetry, and elemental sulfur by photometry. It was confirmed that the total sulfur content is approximately equal to the sum of sulfide sulfur, elemental sulfur, thiosulfate sulfur, sulfite sulfur and sulfate sulfur. Each content of elemental sulfur, thiosulfate and sulfate had a close correlation with the sulfide content in the total sulfur con-tent (correlation coefficient 0.96). Therefore, the contents of these sulfur species could be estimated easily from the analytical values of sulfide and total sulfur. It was found that the smaller the particle size of slag, the more oxidation of sulfur species occurred on standing, and that finally the content of sulfide in slag decreased rapidly to produce sulfate when it was exposed to sunlight, wind and rain water in the atmosphere.