Research On The Characteristic And Utilization Of Low Grade Bauxite

The low grade bauxite has not been well utilized because of its high contents of impurities and low refractoriness.The phase composition,the physical and chemical changes in the heating process and the sintering characteristics of bauxite were researched by the XRD,TG-DSC and particle analyze in this paper.On this basis,the application of using low grade bauxite as main raw material to prepare mullite ceramics and proppants were studied.The mullite are widely used in the preparation of various ceramic materials because of its excellent mechanical properties.The mullite ceramics were prepared using raw bauxite and calcined bauxite as the starting materials by traditional sintering method,the effect of content of calcined bauxite and the calcining process of raw bauxite on the mechanical property of ceramic were investigated.Besides,the mechanism of the effect of calcining temperatures of raw bauxite on the flexural strength of mullite ceramics was studied.The results showed that the mullite ceramics could be prepared successfully in 1360 ^oC,the flexural strength could reach 195 MPa,and the suitable calcining temperature of raw bauxite was 1150 ^oC,the holding time was 30 min.In the process of preparing low density and high strength proppants,the components in bauxite served as flux in the sintering process at high temperatures,and the clay was introduced to enhance the plasticity.Finally,the proppants with excellent properties were obtained in 1320 ^oC.The bulk density of proppants was 1.565 g?cm^-3,the performances were 6.51%of acid solubility and 4.65%of breakage ratio under 52 MPa.Moreover,the breakage ratio under69MPa can reach 5.67%,the breakage ratio satisfied the requirement of 10 K grade in the standard of SY/T5108-2014 and ISO13503-2.For the sake of weakening the influence of crystal transformation of quartz in the cooling process on the properties of proppants,a new research method was explored by preparing the high silicon proppant from low grade bauxite,fly ash and other solid waste.Meantime,the effect of chemical compositions of the formula,sintering temperature and holding time on the properties of proppants were studied respectively in this paper.The results showed the bulk density of proppants was 1.352 g?cm^-3,the performances were 4.2%of acid solubility and5.3%of breakage ratio under 35 MPa when sintering temperature was 1240 ^oC and the holding time was 20min.And the breakage ratio satisfied the requirement of 5 K grade in the standard of SY/T5108-2014 and ISO13503-2.