Pretreatment Of Chromite Microwave Heating Processes

Chromium is mainly used in three areas:metallurgy, refractory materials and chemical industries, with important strategic significance. Chromite resources is extreme-poor in China, only account for0.15%of world reserves and distribute scattered with small scale, and nearly half being lean ore (CraO3<35%). Therefore, China depends heavily on importing of chromite concentrate, and has not sufficient capacity to resist the turbulence of international market. Thus, while strengthen exploring domestic chromite resources, carry out research of mineral processing technology in view of the existing chromite resources, improve the utilization rate of resources has increasingly attracted attention.Chromite concentrate not only requires high-grade chromium, the value of Cr/Fe is also an important factor. Low Cr/Fe ratio chromite (Cr2O3/FeO<2.5), even the content of Cr2O3is ideal, it is difficult to smelting high-grade ferrochrome. How to improve Cr/Fe ratio of chromite with a cost-effective method, is issues of concern in the field of chrome smelting.The common agglomeration methods of Chromite fines are sintering, pellets law and briquetting process. Produce carbon ferrochrome with conventional sintering combine smelting furnace is the lowest energy consumption posscess in several agglomeration methods combine smelting furnace process technology. But the energy consumption of conventional sintering process is still high, much higher than ordinary iron ore sintering process.This paper comprehensive analysed the conventional chromite fines pretreatment process at home and abroad, and combined with the basic principle and characteristics of microwave heating, elaborated the application of microwave technology in chromite pretreatment research status at home and abroad, also based on the feasibility and superiority of chromite pretreatment by microwave. Put forward the beneficiation of chromite with combination process of microwave carbothermy prereduction and the process of sintering chromite fines by microwave.(1) The paper studied the pretreatment process of chromite by microwave, with the raw material as South Africa chromite fines and Semi-coke, provided by a special ferroalloy company special ferroalloy company in sichuan province.(2) Exploring experiments of beneficiation of chromite with combination process of microwave carbothermy prereduction showed, reduction chromite fines by microwave heating could obtain good effect of prereduction, provide good conditions for ore dressing. Through the process of microwave thermal prereduction+chemical leaching, could increase the Cr/Fe ratio effectively; microwave thermal prereduction+magnetic separation is not a effective method.(3)Exploring experiments of sintering chromite fines by microwave heating have proved that, the optimum value and range for each factor can be confirmed as:the sintering temperature1000℃-1200℃, the adhesive accessing amount2%, the holding time Omin.The optimum technological conditions for response surface methodology optimizing the microwave sintering chromite fines is:sintering temperature1153"C, sintering time16min, adhesive accessing amount1.90%, and the strength predicted valuesof sintered product are compressive strength11155.8N, drop number95.6849%. Under optimum conditions,compressive strength of the sintered product is11021N, and dropping number94.855%, which is close to the predicted compressive strengh11155.8N, drop number95.6849%. It can be concluded that response surface methodology cando regression analysis and parameter optimization for the process of microwave sintering chromite fines.(4) Through the experiment exploring of this paper, it can be known that microwave heating is an effective means of chromite pretreatment. microwave heating apply to the pretreatment process of chromite, will provide a new way for chromium industry.