Experimental Study Of Coal Slurry Water Settlement With Electric Field

Coal will be the main resource during a long period in the future in China. The development of coal preparation processes is good for coal utilization and environment protection. Coal slurry water settlement plays a very important role in coal preparation processes, which is in relation to the stable operation of the coal preparation plant and the offering of qualified products. Coal slurry water which has a large amount of coal slurry is very hard to settle, what is more, it is a very common phenomenon among the coal preparation plants. Doing the research on coal slurry water settlement with electric field is a good way of finding new method of coal slurry water settlement.Taking the detection of the coal slurry water from a coal preparation plant in Huainan as the foundation, experiments on coal slurry water settlement with both contiguous and non-contiguous electric fields focus on the effects of electric fields giving to coal slurry water especially experiments on the effects of the condition of the electric field and coagulants have been done, the principle on the effects of contiguous electric field has been originally discussed. Results of the experiments indicate some interesting conclusions. Particles whose sizes are bellow0.045mm in coal slurry are mainly kaolinite and quartz which have strong ability of hydrophilia and are hard to settle. As the voltage is not big enough, the non-contiguous electric field almost does not have significant effects on the coal slurry water settlement no matter how long it exists. The pH value rises as the voltage and time enhance when the contiguous electric field exists. The settlement of coal slurry water with contiguous electric fields is improved as the combination effects of electrophoresis and electrocoagulation, the best settlement of coal slurry water comes when the voltage and effective time are3.2kV and30minutes respectively. Polarizations of particles, ions and water molecules in coal slurry water with electric fields, the macroscopic performances of which are chaining and electroviscous effects will affect the coal slurry water settlement. Experiments on the effects of pretreatment with electrocoagulation on coal slurry water, kaolinite and quartz powder with deionized water, as well as experiments on coal slurry water settlement with the combination of electrocoagulation pretreatment and coagulant have done. Results are as follows, the absolute value of the Zeta potential and the pH value of kaolinite and quartz powder with deionized water rise as the voltage and effective time rise. The pH value of coal slurry water, kaolinite and quartz powder with deionized water positive as the voltage and effective time rise, while the absolute value of the Zeta potential rise to a certain degree and keep fluctuating as the combination effects of the cation from electrode corrosion and the rising pH value. Results of coal slurry water settlement with the combination of electrocoagulation pretreatment and coagulant indicate that it is an effective method to improve the effect of coal slurry water settlement, reduce the amount of coagulant, and stop using the polyacrylamide which is toxic. A device which produces coagulants is designed, waste steel parts can be used as the raw material and the cost of the coal preparation plant could be decreased as this device is used.