Purification And Sodium Modification Of Volcanic Sedimentary Type Bentonite

This study was based on the chemical coupling physical compound process for montmorillonite purification in bentonite.First of all,combined with X-ray diffraction analysis(XRD),scanning electron microscope(SEM)analysis the characters such as mineral content in bentonite,so as to determine the impurity species that influence the purification process for of montmorillonite of a bentonite;Secondly,the influence factors in the purification process of montmorillonite were found by preprocessing and sifting the bentonite in shanxi.Again,through physical purification by wet process,namely subsidence,ultrasonic and centrifugal method to deal with bentonite,combined with characterization techniques such as swelling capacity,blue uptake and whiteness to determine the better purification process parameters;Finally,the influence of NaOH concentration,heating temperature and heating time on the properties of montmorillonite in bentonite were studied.The main findings were as follows:The Shanxi bentonite is calcium base bentonite,with montmorillonite content is 68%,the main impurity are calcium feldspar,quartz.The impurities have characterws of large size,low expansion capacity and low glia,which are not conducive to industrial production and need to be further improved.Through the preprocessing and grinding and sieving of bentonite,the study found that the binding force between montmorillonite and impurities such as calcium feldspar was weak and was easily shattered;The montmorillonite in bentonite can be purified by ball mill and sieve,but the purification efficiency was very low.Single factor tset was used to explore the influence of bentonite slurry concentration、mass fraction of(NaPO3)6 and ultrasonic time,with the expansion capacity,than the swelling capacity,blue uptake and whiteness were analyzed and the study found that when the bentonite slurry concentration was 10%,(NaPO3)6 mass fraction was 0.08%,ultrasonic for 30 min,the study got a purification sample that the swelling capacity was 20.1 mL/g,the whiteness was 93.09,the blue uptake was 0.4083g/g,the content of montmorillonite was increased from 68%to 92.37%,and the recovery rate was over 53.24%.The wet method was good for removing the calcium feldspar in bentonite,but can not remove quartz and still needs to be processed by chemical method.The NaOH solution was used as the sodium agent for the purified bentonite,and the control parameters of the orthogonal experiment was the concentration of NaOH solution,heating temperature and heating time.The study found that when the concentrate of NaOH was 3.13%,the reaction temperature was 80℃ and the heating time was 1.5h,the performance of sodium bentonite was better.The high concentration of NaOH was noticeable for Si02 removal,but it also damaged the structure of montmorillonite in a certain extent.Combined with XRD and swelling capacity analysis results show that after the sodium bentonite layer spacing was changed from 15.120 A to 11.748 A,swelling capacity increased from below 10 mL/g to 91 mL/g,The bentonite slice layer was more dispersed and belongs to sodium bentonite.This study is of great significance to improve the purification and sodium modification of volcanic sedimentary montmorillonite and the comprehensive utilization of resources in the Shanxi Province.