Study On Calcination Desulfurization And Digestion Performance Of High-Sulfur And High-Silica Bauxite

With the high-speed development of the aluminum industry in China,the high-quality bauxite is increasingly poor.The high-sulfur bauxite reserves are huge,of which 42.8%belong to the high-sulfur high-silicon aluminum soil,and only 200million tons of high-sulfur high-sulfur high-silicon ore in Guizhou is in the unmined form.The development of this kind of ore is an effective way to relieve the stress of ore resources.At present,the research focus of high-sulfur and high-silicon bauxite is focused on the roasting and desulfurization and desiliconization,and the structure and composition of the ores are different,and the process parameters are different.Therefore,the process of roasting and desulfurization-high-pressure dissolution is adopted for the two kinds of ore in different areas A and B.By studying the characteristics of the ore,the temperature,time and the roasting method are explored to the desulfurization.The dissolution properties of the ore were studied by comparing the dissolution properties of the ore.On the basis of the study of ore characteristics,the dissolution mechanism of class B ore is studied by dissolution thermodynamics,kinetics,solution structure and crystal.The main conclusions are as follows:A,B ore composition Al₂O₃ 62.83%?52.6%,SiO₂ 16.42%?12.55%,TS 1.2%?2.66%,Fe₂O₃ 4.15%?11.16%,TiO₂ 2.37%?3.57%.Class B ore has the characteristics of low aluminum,medium high iron and high sulfur.After calcination at 600?-90s,the TS of type B roasted ores decreased to 0.32%and 0.58%respectively,and the desulphurization rate was 73.33%and 79.86%,respectively.The TS of class B ores decreased to 0.5%after calcination at high temperature.The main phases of the original ore are diaspore and kaolinite,but there is a soft aluminite phase in class A ore,which disappears after calcination at low temperature.The phase of type B high temperature ore is mainly?-alumina,silica,hemite and anatase.The desulphurization effect of static roasting is better than that of suspension roasting,and the desulphurization effect of B ore is better than that of A ore.The desulphurization effect can be improved by increasing calcination temperature and prolonging time.When the static calcination temperature is 600?and the calcination time is 180S,the sulfur content of the ore decreases from 1.2%,2.66%to 0.29%,0.49%,and the desulphurization rate is 75.83%and 81.58%,respectively.Mineral morphology has an important influence on dissolution,and the dissolution performance of Class A ore is better than that of Class B ore.When NK245g/l,70min,8%lime was added and calcined at 280?,the relative dissolution rates of B and B ores were 97.52%and 96.02%,respectively,which were significantly better than those of raw ores.After calcination at high temperature,the dissolution rate of class B ore is low,and the dissolution rate of class B ore is only92.26%by pre-desilication.The dissolution thermodynamics shows that when aluminum minerals exist in the phase of diaspore,kaolinite,alumina and so on,kaolinite reacts with caustic soda to form NaAlO₂,while pyrite is easy to react with caustic soda to form Na2S,resulting in an increase in alkali consumption.It is found that the reaction restriction link of middle and low grade high sulfur bauxite is internal diffusion in the process of dissolution kinetics.In the process of low temperature calcination,the crystal of diaspore becomes smaller and changes to alumina with poor crystallization degree,which is beneficial to the improvement of dissolution effect.When the temperature increases and the time prolongs,the crystallization degree of alumina increases and the crystal size increases gradually,which is not conducive to dissolution.After hydrogen peroxide oxidation And the complex dimer ion structure of the circulating mother liquid is changed,the chemical activity is enhanced,and the dissolution of the bauxite can be effectively promoted.