Study On Extraction Of Iron Powder From High-iron Bauxite By Deep Reduction

With the rapid and continuous development of aluminum and iron industry in China, high-grade bauxite resources supply tension increasingly, comprehensive utilization of low-grade bauxite resources are paid more and more attention. There are a large number of high-iron bauxite in Guangxi, due to technical and economic issues, these bauxite has not been exploited yet. The existing technologies of ironmaking pollute environment seriously, from the perspective of clean energy, it is of practical significance to reduce high-iron bauxites by hydrogen.This paper aims at extracting iron powder from high-iron bauxite in Guangxi, which is studied, firstly hydrogen and natural gas were used as the reducing agent, reduction temperature, reduction time and material thickness have effect on the reduction degree of iron oxide, which was studied, and a suitable reduction process was obtained, meanwhile the two sets of parallel experiments were carried out, as result that the reduction technology was determined. On this basis, in this paper pure substances and the corresponding mineral components in high-iron bauxites were compared by thermal analysis techniques, mechanism functions that hematite in high-iron bauxite were reduced by hydrogen were to determine, and gibbsite dehydration mechanism function was also determined, the apparent activation energy E, pre-exponential factor A and the kinetic equation in reaction is obtained by calculating.the conclusions is followed:(1) Using hydrogen as the reducing agent, when the reduction temperature is800℃, reduction time is90min, material thickness is5mm, iron oxides in the high-iron bauxites can be reduced to metallic iron, through the magnetic separation, iron elemental mainly exists in the form of metallic iron and are riched in magnetic material, aluminum, silicon are enriched to in non-magnetic material, separation of iron and aluminum is achieved.(2) Using natural gas as the reducing agent, when the reduction temperature is800℃, reduction time is120min, material thickness is5mm, iron oxides can be reduced and form of metallic iron, metallic iron is enrichment to the magnetic material, by the magnetic, aluminum and silicon are enriched to a non-magnetic material, the separation of iron and aluminum are realized.(3) Five different grain size of the nano-iron oxide reaction mechanisms function is g(a)=[1-(1-a)1/3]2which is determined by using Coats-Redfern method with experimental data, and the apparent activation energy of the reaction of nano-iron oxide increases with the increasing of grain size. The AR iron oxide reduction mechanism function was determined, which is g(a)=[1-(1-a)1/3]1/2, using the mechanism the apparent activation energy E of hematite in high-iron bauxite is65.610kJ·mol-1, the pre-exponential factor A is2.4458×103and the kinetic equation is AR gibbsite dehydration mechanism function is g(a)=[(1-α)-1/3-1]2, using the mechanism function, gibbsite in high-iron bauxite is calculated, apparent activation energy E is421.022kJ·mol-1, the pre-exponential factor A is3.0159×1038and the kinetic equation...