Study On The Settlement Characteristics Of Coal Slurry Containing Montmorillonite

For a long time, coal slurry purification has been the difficulty of the production management in most coal preparation plant. The clay minerals in slime water will seriously deteriorate the effect of coal slurry treatment due to its nature.In this paper, montmorillonite was selected as the research object, because of its serious effect to coal slime sedimentation. Montmorillonite with high purity and low ash coal were firstly prepared to be samples. Later the characteristics of particle size, surface morphology, electrical properties and functional groups of these samples were determined through particle size analyzer, scanning electron microscopy, zeta potential analyzer, fourier transform infrared spectrometer etc. Through the microscopic analysis, it was found that after the immersion in water, montmorillonite would shatter into very fine particles and adhere to the coal particles when mixed with coal, which increase the overall electrical negative and negative electrical functional groups, hence the settlement of coal slime with montmorillonite would be very difficult.Through the natural sedimentation test, it was believed that the high purity coal and the coal slurry with montmorillonite in the deionized water were very difficult to settle. However, pure montmorillonite settled dowm though its compression layer was fluffy and the supernatant was turbid. With the increase of water hardness, the settlement effect became better gradually but the swelling of montmorillonite has a serious impact on the effect of coal slurry, so the compression layer is still loose.According to the flocculation sedimentation test, the effect of the comprehensive settlement of the coal slime water containing montmorillonite under the action of the coagulant Al Cl3 is better than the coagulant Ca Cl2. The comprehensive influence on the sedimentation effect :concentration of slurry, the montmorillonite content,and the dosage of coagulant were studied by a three factors and five levels orthogonal test. According to the experimental results, the settlement models of the settling velocity and the supernatant turbidity were obtained, which can be used to predict settlement effect in the actual production.By settling floc fractal dimension analysis, adding coagulation agent can make the flocs becomes larger, and with increase of dosage, the changes in the floc fractal dimension has certain rules,so fractal dimension can be used as one of the evaluation indexes of sedimentation effect.