Research On The Settlement Of Coal Slurry With Microwave Irradiation Preprocessing

At present, the treatment methods of slime water in coal preparation plant are mainly flocculation sedimentation in our country. However, the coal quality of our country is relatively poor in general, high ash coal accounted for the main part; and there is a serious phenomenon of mudding in coal washing,so that the coal slime is difficult to settlement. Therefore, the reagent addition is increasing while treating slime water, and the cost of purchasing flocculant is also increasing. In this experiment, the microwave technology and flocculation sedimentation technology are combined to form the microwave-flocculation technology to treat the slime water, in order to reduce the usage of the reagent and save the cost of the reagent.This article experiment research on the slime water in Huainan Wangfenggang coal preparation plant.Firstly, experiment research on some basic properties of slime water. Doing small screening test to coal slime by the Vibrating Screen,analyze particle size and ash distribution of -0.5mm coal slime; analyze the mineral composition of coal slime by the X-ray diffraction; analyze the size composition of-0.045mm coal slime by the laser particle size. The results show that, the coal slime particles of -0.045mm accounted for 86.94%, ash for 56.48%, belonging to the high ash fine slime. In the coal slime particles of -0.045mm,there are 78.37% slime size smaller than 0.01mm, which are difficult to settlement in slime water. There are clay minerals (kaolinite、montmorillonite、quartz and so on) in the coal slime, The zeta potential of slime water is -25.1mV, the clay mineral particles in slime water are mutual exclusiveness, forming a relatively stable structure, so that it is difficult to settlement.Then, the experiment research on the treatment effect of slime water for the single flocculant and single coagulation, and determine the best the reagent addition under different conditions of coal slime.And then the experiment research on the sedimentation effect of coal slurry after microwave pretreatment adding flocculant、 coagulation, microwave power、irradiation time and reagent addition are taken to orthogonal test of three factors and three levels, test results take slime water transmittance、the initial settlement speed and clarified sediments height as evaluation index.through intuitive analysis to determine the important order of the influencing factors and the best combination of factors under different conditions. And then the experiment further study the mechanism of flocculation,and the mechanism of microwave assisted it. The experiment results show that:(1)While using anionic polyacrylamide (APAM) flocculant in treatment of slime water, single flocculant working, the optimum flocculant dosage is 1.2ml (0.0048g/L), after 20min settlement, the transmittance is 86.7%. While using the microwave-flocculation combined technology, flocculant dosage can be reduced to 0.7ml (0.0028g/L), the effect of settlement of slime water is basically the same with that of single flocculant addtion of 1.2m1(0.0048g/L).(2) While using alum (12H2O.KAl (SO4) 2) coagulant treatment of slime water, single coagulant working, the optimum coagulant dosage is 14ml (0.56g/L), after 20min settlement, the transmittance is 92.4%. While using the microwave-coagulation combined technology, coagulant dosage can be reduced to 10ml (0.4g/L), the effect of settlement of slime water is basically the same with that of single coagulant addtion of 14ml (0.56g/L).(3)Appropriate microwave power and irradiation time can improve the sedimentation effect of slime water, reduce the usage of the reagent and save the cost of the reagent; but the higher microwave power or longer irradiation time can reduce the sedimentation effect of slime water.(4) the sedimentation effect of microwave heating and flocculant combination technology on coal slime sedimentation is better than that of conventional heating and flocculant combination technology.