Study On Preparation, Characterization And Application Of High-purity Bentonite

High-purity bentonite and inorganic gel are important ways to enhance the added value of bentonite. In this thesis, the preparation process, characterization, and application property of high-purity bentonite and inorganic gel were researched systemically.A new pure sample graduation method was proposed based on the CEC values of test samples and pure sample. Influence of impurity, exchengeable cation type and edge charge to measuring results were considered. Using weighted method, Na-bentonite sample and pH=4 were recommended as the test condition.Preparation process of high-purity bentonite was systemically studied. The optimal conditions are as follows: rotational speed is 1500rpm, ore slurry is 10%, use level of Na₄P₂O₇ is 1%, jitter time is 1 hour, rotational speed of centrifugal machine is 2000rpm, use level of NaOH is 10%, temperature of alkali solution is 85℃, time of alkali solution is 2 hours. Results of XRD, chemical constitution analysis and performance measurement show that montmorillonite content of preparation concentrate is greater than 95% and the performance indexes of preparation concentrate are far better than that of raw ore.Performance influence factors of inorganic gel were optimized. Test results indicate that low layer charge and high montmorillonite content are demanded; slurry concentration is from 5% to 6%; pH value should be approached to 7; room temperature can be adopted; and ball milling time is 50 minutes. Furthermore, interfusion of electrolyte and increase of water content are adverse to gel quality. Test results of rheologic behavior of WF inorganic gel show that WF, SM inorganic gel are all plastic body liquidity, whose viscosity reduces as the shear rate runs up. The static shearing stress values are 33.98Pa, 45.16Pa respectively; the moving shearing stress values are 91.89Pa, 78.93Pa respectively; and the thixotropic values are 95.2dyne·s/cm², 83.7dyne·s/cm² respectively.Results of application of inorganic gel in dentifrice show that the optimal return-service rate of inorganic gel and CMC is 3:8. Contrast tests show that return-service effect of WF inorganic gel with middle and low layer charge and CMC is better than that of LX inorganic gel with high layer charge, WF Na-bentonite and CMC, and it can be compared with SM. Results of application of high-purity bentonite in medicine declare that indexes of WF, LX samples all measure up to industry standard, so both of them can be used as the medical material.