Comprehensive Utilization Of High Sulfur Bauxite

With the development of alumina industry, the demand for bauxite continued to increase, while high-grade bauxite resources are increasingly scarce, so research the way to use the low grade bauxite is of great significance. Because of the particularity of the composition and structure, high sulfur bauxite what accounting for a large proportion of diasporic bauxite of China’s bauxite resources is not widely used for alumina production. So study the process of high sulfur bauxite to produce alumina and bauxite resources comprehensive utilization is of great significance to promoting the circular economy development of China.This paper designed the process of high sulfur bauxite-sulfuric acid roasting to produce alumina on the basis of analysed the composition and nature of the raw mineral, and realized the separation and utilization of valuable elements. Employing bauxite and sulfuric acid as raw materials, aluminum and iron were extracted from bauxite by the method of sulfatizing roasting, and obtained as sedimentation in digestion process, then separated in the form of sodium aluminate and ferric hydroxide by alkali extraction of the sedimentation mentioned above. Used sodium hydroxide to dissolve the precipitated mixture, and got the ferric hydroxide and sodium aluminate, so finished the separation of aluminum and iron; Finally, iron oxide and alumina were obtained through further treatment.The experiments researched the influence of roasted temperature, the ratio of sulfuric-to-ore and holding time on the extraction rate of aluminum and iron in the process of bauxite-sulfate acid roasting. On the basis of the single factor experiments and orthogonal experiments, the optimum conditions of roasted process were obtained:roasting temperature was350℃, the ratio of sulfuric-to-ore was2.75:1, holding time was180min, extraction rate of Al was more than83%, extraction rate of Fe was more than99%.The influence of the ratio of water-to-sulfuric, dissolution temperature and time on the extraction rate of aluminum and iron were researched during the dissolution process. The dissolution conditions:the ratio of liquid to solid was6:1, dissolution temperature was95℃, time was30min. The experiments researched the technology of separation of aluminum and iron in the leaching solution. Adjusted the pH value of the solution to precipitate aluminum and iron by ammonium bicarbonate, achieved the separation of aluminum and iron after treated the precipitation with sodium hydroxide. The conditions of precipitate aluminum and iron:pH value was6.0, reaction temperature was50℃, reaction time was60min. The conditions of alkali-soluble:the ratio of alkali to aluminum was3.5:1, reaction temperature was95℃, time was30min, the dissolution rate of Al(OH)3reached99.5%.Ferric hydroxide and sodium aluminate solution were obtained from the reaction of alkali-soluble, the ferric hydroxide was used to produce iron oxide by calcination reaction. Sodium aluminate was used to produce aluminum hydroxide, then prepared alumina by calcining aluminum hydroxide.