Calorimetric and fourier transform infrared spectrophotometric studies of potassium elimination by dunite

This report contains the results of simultaneous and comparative differential thermal, thermogravimetric, and Fourier transform infrared spectrophotometric 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 magnesium content of the slag and to eliminate alkaline elements, principally potassium. However, the use of dunite is less known and can have certain advantages over olivine. In this investigation, a dun ite-coke-K₂CO₃ system was studied to simulate the operating conditions of a furnace in temperatures up to 1200 °C. The results obtained show that the reaction begins with the dehydration of dunite and its transformation into forsterite and enstatite. This is followed by the fusion of potassium carbonate and, at temperatures between 1000 °C and 1200 °C, a series of consecutive chemical reactions that includes the formation of potassium vapor and its reaction with enstatite and clinoenstatite, possiblyvia an intermediate phase in which unstable potassium iron silicates are produced. Ultimately, this leads to the formation of magnesium potassium silicate complexes. In the blast furnace, this silicate would be incorporated into the slag, taking with it the potassium brought in by the coke and iron ore of the load.