The Development And Properties Characterization And Its Application Of Low-to Medium-Grade Bentonite

In this dissertation, the studies were finished on wet process of purification,modification, organizing and its application of low-to medium-grade bentonite from Xiazijie Bentonite Mine which possesses abundant reserves. Firstly ,the mineralogical and physicochemical properties of Xiazijie bentonite were tested and characterized. It was proved that the three samples belonged to all low-to medium-grade sodium-type bentonite,which can be developed and used widely because of good physicochemical properties. Secondly , each sample was studied by purification with different technics.The content of montmorillonite reached 93.40% after the bentonite(PRT-3) from Wulanlingge was purified by natural sink with water.The content of montmorillonite of bentonite(PRT-3) from Wulanlingge reached 99% by high-speed centrifugal. The content of montmorillonite of bentonite(PRT-3) from Riyuelei reached 87.17% after natural sink. Meantime, the study of the modification of calcium bentonite was made .It was shown that NaF was one kind of good sodium salt for modification .Its CEC reached 67.88mmol/100g bentonite and was improved 24 mmol/100g compared to crude mine when the bentonite was modified in optimum process condition. It can be shown from organizing that the properties of gel was better when the ratio of HDTMA to bentonite is 85-90 mmol per 100g bentonite.The structures and morphology of the organo-bentonite were characterized by Fourier-transformed infrared (FTIR), X-ray diffraction (XRD) ,scan electron microscopy (SEM) and TG. FTIR scan showed that the HDTMA was intercalated into the silicate crystal layers of the clay. Increase in the spacing between the adjacent silicates layers from 1.23 nm to 3.26 nm were determined by XRD.It was observed by SEM that the organo-clay was less compact in comparison with the original samples, and the dimensional scale of the clay particles were dropped into the nano-level, it was suggested that the spacing of layers reached about 72 nm. TG shew that the CEC between the crude clay and 1631 was 71.13mmol/100g , the CEC between the crude clay and CTAB was 73.34mmol/100g .Consequently, the organo-clay was applied in the preparation of oil based drilling mud and in dope. Organobentonite basically is up to all quality index, and showed good to excellent performance in all compulsory test items. It was demonstrated that the development of low-to medium-grade clay into high performance organo-bentonite was practical.