| The low-grade bauxite is not fully applied in the Chinese alumina metallurgy industry, for the reason that low-grade bauxite contains low concentration of aluminum and iron. In order to promote the development of recying economy and builde a conservation-social society, it is meaningful to carrying out low-grade bauxite comprehensive recying research. The small partial size of aluminum and iron in the bauxite mingles together, and also the single useful element has poor separation ability. If the bauxite is separated only considering the single point of iron or alumina, the higher operation cost and difficult treat technology are current issue. In this paper, based on the analysis and testing of the nature of raw material, Al, Fe, Si were comprehensive recyed using bauxite-sulfuric acid roasting method. Through condition experiments, the relevant suitable conditions for process were determined and the process was created. The major elements were as follows:(1) The influence of roasted temperature, holding time, the mass ratio of sulfuric-to-ore, the mass ratio of water-to-sulfuric on extraction Al2O3and Fe2O3in the bauxite-sulfuric acid roasting process were studied.The orthogonal test was desiged on the basis of sigle factor experiments, the best roasting conditions were agained:roasted temperature350℃, holding time two hours, the mass ratio of sulfuric-to-ore1.7, the mass ratio of water-to-sulfuric0.5. under such conditions, the extraction rate of Al2O3and Fe2O3was up to98%. Diluted H2SO4was used to absorb the SO3from roasting bauxite process in order to produce the H2SO4which can be circularly used as the raw mater for roasting.(2) The influence of dissolution temperature, holding time, the mass ratio of sulfuric-to-ore, the mass ratio of water-to-sulfuric on extraction Al2O3and Fe2O3were studied during the dissoluting process. The suitable conditions were agained:the dissolution temperature95℃, the time of dissolution30min, the ratio of dissolution liquid to solid5:1. under such conditions, the extraction rate of Alumina and iron oxide was up to98%.(3) The SiO2product can be obtained after washing and drying the roasting leaching residue. the silica content of it was more than90%.(4) Precipitate iron With (NH4)2Fe6(SO4)4(OH)12method from the solution that dissolution of the roasted clinker, the influence of the pH, reaction temperature and reaction time on the precipitation rate of iron and the loss rate of aluminum from the dissolution liquid were studied, the suitable conditions were agained:the end pH value3.5, reaction temperature95℃, reaction time three hours, the precipitation rate of iron was up to96%, the loss rate of aluminum was about7%.(5) Fe2O3was obtained by roasting and hydrolyzing (NH4)2Fe6(SO4)4(OH)12. The content of Fe2O3was96.94%after roasted at650℃for2h, and the content was90.83%after hydrolyzed at the end PH value of10. H2O was used to absorb the SO3and NH3from roasting (NH4)2Fe6(SO4)4(OH)12. process in order to produce the (NH4)2SO4.Diluted H2SO4was used to absorb the suplus NH3from hydrolyzing (NH4)2Fe6(SO4)4(OH)12.(6) After Precipitating iron, the NH4Al(SO4)2solution was prepared (NH4)2CO3solution. Throuth studing the influence of reaction temperature,(NH4)2CO3concentration and the mass ratio of (NH4)2CO3to NH4A1(SO4)2on the Al Precipitation ratio and Filtration rate. The suitable conditions were agained:the reaction temperature45℃, the (NH4)2CO3concentration1.75mol/L, the ratio of raw material3.75. The Al Precipitation ratio was up to99%, and the filtration rate was430ml/min.(7) The AACH was calcined at1200℃for1.5h, Al2O3.product was obtained, the product was almost Al2O3acorrding to the test. |
PDF Full Text Request