IMPROVING LIMESTONE-NEPHELINE CHARGE SINTER QUALITY BY GYPSUM ANHYDRATE TECHNOGENIC RAW MATERIAL INTRODUCTION

Abstract

The PURPOSE of the paper is to study the possibility to change the quality indicators of limestone-nepheline charge sinter by the introduction of gypsum anhydrate technogenic additives (GATA). METHODS. The study uses physico-chemical computer modeling based on the thermodynamic analysis, as well as thermoanalytical, electronic and microscopic research methods, an X-ray phase and X-ray diffraction analysis. RESULTS. Introduction of GATA in the proportion from 0.2 up to 2% of the charge weight into the limestone-nepheline charge increases the reactionary ability of components and decreases the sinter formation temperature by 30-70ºС. When entering the reaction, calcium sulfate contributes to the formation of Ca₂SiO₄ and NaAlO₂, as well as the sulfates of alkaline metals - K₂SO₄ and Na₂SO₄. The researches have shown that the introduction of 0.4% of GATA in the charge increases the content of sulfur oxide in sinter from 0.28 to 0.38%, while the raise in the sintering temperature from 1230 to 1290ºC increases sulfate extraction from sintered material up to 67.2 and 89.7% respectively. CONCLUSION. Pilot tests have shown that introduction of gypsum anhydrate technogenic raw materials in the proportion of 0.4% wt of furnace charge increases the output of potassium sulfate by 11900 tons/year as well as reduces the consumption of limestone under charge sintering by 35600 tons/year.