CALORIMETRIC AND FOURIER-TRANSFORM INFRARED SPECTROPHOTOMETRIC STUDIES OF POTASSIUM ELIMINATION BY DUNITE

This report contains the results of simultaneous and comparative diffe rential thermal, thermogravimetric, and Fourier transform infrared spe ctrophotometric studies of the interaction between K2CO3 and a mineral of dunite. The use of olivine during the reduction of iron oxides in the blast furnace is a common practice employed to increase the magnes ium content of the slag and to eliminate alkaline elements, principall y potassium. However, the use of dunite is less known and can have cer tain advantages over olivine. In this investigation, a dunite-coke-K2C O3 system was studied to simulate the operating conditions of a furnac e in temperatures up to 1200 degrees C. The results obtained show that the reaction begins with the dehydration of dunite and its transforma tion into forsterite and enstatite. This is followed by the fusion of potassium carbonate and, at temperatures between 1000 degrees C and 12 00 degrees C, a series of consecutive chemical reactions that includes the formation of potassium vapor and its reaction with enstatite and clinoenstatite, possibly via an intermediate phase in which unstable p otassium iron silicates are produced. Ultimately, this leads to the fo rmation of magnesium potassium silicate complexes. In the blast furnac e, this silicate would be incorporated into the slag, taking with it t he potassium brought in by the coke and iron ore of the load.