The Separation And Extraction Process Of Iron And Aluminum From High Iron Gibbsite Ore Based On Metallic Reduction And Self-disintegrating

With the rapid development of China’s economy,the domestic demand of iron ore and aluminum ore is gradually increased,which leads to the heavily reliant on imports.High iron gibbsite ore in Guangxi province is a type complex ore,which owns high iron content,high silica content and low mass ratio of Al2O3 to SiO2(A/S).Since the contents of iron and aluminum do not meet the requirements for industrial application of each other,and the iron and aluminum minerals are joined with each other,complex and the monomer dissociation performance is poor,the high iron gibbsite ore have not been reasonably developed and utilized so far.The comprehensive utilization of high iron gibbsite ore has an important significance in the development of steel industry and aluminum industry of China.Based on previous studies,the process of separating and extracting iron and aluminum from high iron gibbsite ore based on metallized reduction and self-disintegrating was put forward in this paper.Firstly,the preparation of high iron gibbsite carbon composite iron ore hot briquette(Al-CCB)was investigated in the laboratory.The effects of hot-briquetting temperature,carbon ratio,flux addition ratio(molar ratio of CaO to Al2O3,abbreviated C/A)on cold crushing strength of Al-CCB were researched,and the optimum preparation parameters of Al-CCB were determined.Secondly,the experimental studies on the metallized reduction and self-disintegrating of Al-CCB were carried out.The influences of reduction temperature,carbon ratio,reduction time,C/A,cooling rate and cooling temperature on the process indexes were investigated and the iron particles and the calcium aluminate slag under optimized conditions were obtained.Thirdly,the experiments of extracting aluminum from calcium aluminate slag were carried out.The effects of Na2CO3 concentration,leaching temperature,leaching time and the ratio of liquid to solid on leaching ratio of alumina were studied.Finally,the carbothermic reduction thermodynamics of high iron gibbsite ore were discussed.With systematical researches,some conclusions were obtained as follow:(1)To some extent,with increasing hot-briquetting temperature and carbon ratio,the crushing strength of Al-CCB is increased.However,the effect of flux addition ratio on the crushing strength of Al-CCB is not obvious.The suitable preparing parameters of Al-CCB are hot-briquetting temperature 3500℃,carbon ratio 1.0 and C/A 1.7.Under this condition,the crushing strength of Al-CCB is no less than 920 N,which could meet the requirements for industrial application of Al-CCB.(2)The results of metallized reduction and self-disintegrating of Al-CCB show that,reduction temperature and carbon ratio have great influences on the recovery ratio of iron.While,the reduction temperature,reduction time,C/A,cooling rate and cooling temperature have significant effects on the self-disintegrating ratio of calcium aluminate slag.The appropriate process parameters of metallized reduction and self-disintegrating include reduction temperature 1425 ℃ reduction time 25 min,carbon ration 0.9,C/A 1.7,cooling rate 5℃/min and cooling temperature 1225 ℃.Under these conditions,the recovery ratio of iron and aluminum are 97.42%and 94.62%,respectively.Moreover,the self-disintegrating ratio of calcium aluminate slag is up to 97.53%.(3)The TFe and C content,metallization ratio of iron particles obtained at the optimal conditions are 92.74%,4.90%,and 97.27%,respectively.The Al2O3 content of calcium aluminate slag is 29.17%.The main phase minerals in calcium aluminate are 12Ca0·7Al2O3 and γ-2CaO·SiO2,in which the 12CaO·7Al2O would be used to extract alumina.(4)The results attained from the experiment of leaching aluminum from calcium aluminate slag show that,the leaching ratio of alumina is increased and then decreased with increasing leaching time.While firstly increases and then tends to level off with the increase of leaching temperature.Additionally,leaching ratio of alumina is increased with the increase of Na2CO3 concentration and liquid to solid ratio.The optimal leaching parameters are Na2CO3 concentration 100 g·L-1,leaching temperature 60℃,leaching time 100 min and the ratio of liquid to solid 12.5.At the conditions of optimal parameters,the leaching ratio of calcium aluminate slag is 86.20%.(5)Based on the principle of stable existence of minimum ΔG0T,the solid reaction thermodynamics and carbothermic reduction thermodynamics of solid phase reaction products of FexOy-Al2O3-CaO-SiO2 complex system in high iron gibbsite ore are researched.The results show that,compared with FeO,alomost all the composite phases containing FeO have worse reducibility.The higher temperature and higher partical pressure of CO are required for reducing the FexO to Fe in the complex system,separating iron from Al2O3 and SiO2.