Studies On The Technology Of Al-Fe Separation Of High-Fe Bauxite

Metals such as iron and aluminum are important raw material for our national economic development. The lack of easy selective iron ore and bauxite results in high degree of dependence on foreign trade. However a large amount of high-Fe bauxite has been found in China especially in Guangxi, Fujian, Shanxi provinces etc. The exploitation and utilization of high-Fe bauxite makes a significant importance for the sustainable development of our mining economy.Generally, magnetic separation, flotation or magnetic separation-flotation united process are adopted to deal with common ore, and magnetization roasting with refractory ore. But some of those can’t to be used to separate closely embedded fabric of iron mineral and aluminum mineral. This paper uncovers the mechanism of high-Fe bauxite reduced and sintered by CaO and carbon.Chemical composition, mineral components and contents, mineral association and mineral grain size distribution of high-Fe bauxite from Sichuan province are studied by means of chemical analysis, optical microscopy, and x-ray diffraction (XRD). It is indicated that the raw ore contains TFe22.56%, Al2O336.26%, the main minerals bearing iron and aluminum in the ore contain gibbsite, hematite and limonite, the main structure of gibbsite is fine scaly structure and cryptocrystalline structure, and the main structure of hematite is granular structure, irregular structure, honeycomb structure, and the main structure of limonite is colloidal structure. Hematite involucra circles around the gibbsite aggregate while gibbsite usually occurs in the interspaces of colloidal and honeycombial hematite.The effect of calcium oxide content on metallization rate and magnetic separation of the reducted-sintered material and leaching efficiency of rich-aluminum slag are analyzed. The Al-Fe separation index is evaluated on the basis of retention rates of TFe and Al2O3.The result shows that optimal addition amount is70percents. Combining with components and microscopic structure of the reduced and sintered product and relevant thermodynamics reaction, it can be concluded that the addition of CaO improves the reduction of iron oxide and the production of12CaO·7Al2O3and2CaO·SiO2which is favorable for the separation of iron and aluminum.Conditions of reduction-sintering such as temperature(1350℃), time(20min), carbon additive coefficient(2.0) and particle size(-0.18mm)are determined on the basis of retention rates of TFe and Al2O3. A performance of iron powder with grade89.93%, recovery84.08%was given in the conditions of grinding fineness-0.074mm91%and magnetic field intensity60kA/m.The reduction-sintering process of high-Fe bauxite is a compound reaction which includs the process of Fe2O3â†'Fe involving direct reduction reaction and indirect reduction reaction and the process of Al2O3â†'M2CaO·7Al2O3which was influence by temperature and calcium oxide content.Each reaction takes place in different degrees in different stages of reduction-sintering process of high-Fe bauxite. The reduction of iron oxide and the calcium salinization of alumina were conducted slowly at950℃, and conducted deeply as the temperature rises, local slightly melting phenomenon was discovered at1325℃, the two processes reacted thoroughly at1350℃which favours the separation the iron from aluminum.