Research On Dissolution Performance Of High Ferrous And High Titaniferous Bauxite

The shortage of high quality bauxite resources in C hina is becoming increasingly obvious, and the production costs of Al2O3 remain high. Therefore, the conflict of supply and demand in bauxite could be solved by studying the application of dealing with complex refractory bauxite. Refractory bauxite from Yunnan was studied, the mineral characteristics, dissolution properties and mineral reaction behavior were studied to obtain theoretical basis of the bauxite in this paper.The results of mineralogical characteristics show that the ore was of diasporic bauxite with high ferrous and high titaniferous, the content of Al2O3 was 54.35%, and A/S was 8.02; ferrous mineral in ore was mainly hematite with a small amount of chlorite; titanium mineral was mainly anatase, which also contain ilmenite formed by a small amount of Fe and Ti. Diasporic bauxite in the ore output through aggregation of gravel sand and clastic, hematite output through aggregation of compact mass, lamellar and mud with sand, anatase mainly output through small shape.The dissolution performance of bauxite shows that titanite drgged some certain amount of Al2O3 into red mud, which lead to low dissolution ra te of alumina, sodium alumino silicate hydrate, hydrate garnet and cancrinite also lead to the loss of Al2O3. Fe2+ in chlorite could eliminate the harm caused by TiO2, but chlorite ore content was low, which did not significantly affect the dissolution rate of alumina, the addition of lime could eliminate the influence of TiO2. In the high temperature section(250~280℃), the anatase has some effect on the dissolution of alumina, but the effect of the dissolution is relatively weakened with the strengthening of the dissolution conditions. Better dissolution conditions were obtained: amount of lime addition was 8%, solution temperature was 270℃, caustic concentration was 225g/L, dissolution time was 60min; under these conditions, dissolutio n rate of Al2O3 was 77.74%, dissolution rate of Fe2O3 was less than 3%, dissolutio n rate of TiO2 was only 5%.Kinetic experiments results show that the digestion behavior of Al2O3 could be described by regional reaction kinetics equation of Hulbert-Klawitter, that the kinetics is [?ln(1?x)]2/3 ?kln t ?C, apparent activation energy of reaction was Ea=43.296kJ/mol, the process was controlled by surface chemical reaction, but mass transfer process still affected the reaction rate, which can not be ignored. The dissolution behavior of TiO2 was well described by kinetic equation, that the kinetics is 1/32 t ?K[1?(1?x) ] ?C and the apparent activation energy was Ea=77.320 k J/mol, which was controlled by chemical reaction.