Study On Solid Phase Reaction Properties Of K-feldspar System In Baiyunebo Iron Ore Sintering

Baiyunebo iron ore, as the main raw material containing iron for Baotou iron andsteel company, is a special iron ore containing many kinds of deleterious elements such askalium （K）, sodium （Na） and fluorine （F）. In addition, SiO₂and Al2O3in Baiyunebo ironexist as complicated silicate or aluminosilicate of K and Na elements. It is important toexplore Baiyunebo iron ore sintering special compound iron acid calcium complexformation mechanism optimized for special ore sintering environment in order to promotethe formation of acid compound iron calcium, improve the performance of the compositeiron acid calcium, fundamentally solved clad steel high basicity sinter strength andmetallurgy performance issues for Baotou iron and steel company sintering technologyprogress to provide important theory basis. So how to deeply and scientifically analyze theproblem of the forming mechanism of complex calcium ferrite in Baiyunebo iron ore willplay a very important role for Baotou iron and steel company’s improvement of sinteringtechnology.The solid phase reaction of Baiyunebo Iron ore which contains K element in the formof complex silicate and aluminosilicate was studied by means of differential thermalanalysis （DTA） and X-ray diffraction （XRD） in this paper. At the same time, theexperiments focus on the initial products and starting temperature of solid phase reaction.Adopting high basicity sintering, on the one hand,we should take measures in the aspectof mineral separation to decrease the content of silicate and aluminosilicate ganguecontaining kalium （K）, sodium （Na） and the content of fluorine （F）, and increase thegrade of iron ore; on the other hand, we should add appropriate outside iron ore whichcontains free SiO₂and Al2O3gangue, in order to promote the formation and influencingmechanism of complex calcium ferrite in the sintering process of Baiyunebo sintering ore.The results show that the natural potassium slate contain a certain amount of impuritiessuch as potassium nepheline except the main minerals （K-feldspar）,moreover, afterroasting the potassium slate at986degree centigrade, the potassium nepheline andK-feldspar occur solid state reaction and generate leucite with a amount of heat. The bestsynthesizing K-feldspar reaction system is K₂CO₃-Al2O3-SiO₂system and the bestsynthesizing temperature is1000degree centigrade. In the sintering progress ofKAlSi₃O₈-CaO-Fe₂O₃system heated from room temperature to1350℃,2CaO·Al2O3·SiO₂and Ca2SiO4generate at1173℃, the free Fe₂O₃does not take part in the reaction, andSiO₂and Al2O3existing in the K-feldspar are apt to react with CaO to generate silicate and aluminosilicate, but not easy to generate SFCA. In the system of KAlSi₃O₈-CaO-CaF₂andKAlSi₃O₈-CaO-Fe₂O₃-CaF₂, CaF₂can involve in reaction which generate3CaO·2SiO₂·CaF₂, fiercely inhibiting the formation of complex calcium ferrite. Adoptinghigh basicity sintering, excluding the exhaustion of the CaO which take part in the reactionof generate3CaO·2SiO₂·CaF₂, the remaining CaO react with Fe₂O₃at1122℃to generatea high iron low calcium style calcium ferrite Ca2Fe22O33. As the reaction temperaturegrows higher, more and more CaO melt into the system and generate a different kind ofhigh iron low calcium style calcium ferrite （Ca4Fe14O₂5） at1140℃, so high basicity isbeneficial to the formation of SFCA in the sintering progress of Baiyunebo iron ore.