The Dynamics Model Of Coal Slime Water Settlement With The Assistance Of Electric Field

In China2011, the coal consumption have occupied66.4%percentage of energy total consumption, in oder to reduce the pollutant emission by the coal utilization, it is necessary to develop the Clean Coal Technology, however, with the increasing complication of mineral component of the raw coal which was caused by the applyment of mechanization exploit, for the source technology of CCT, the mud of clay mineral in slime water has been increased dramatically in coal preparation industry,which made slime water treatment more difficult. For the purpose of speeding up the slime water treatment and reducing the pharmacy adding, the electric field assisted slime settling technology has been researched and developed via analysising the mechanisation of zeta potential of single slime particle and simulating the setting velocity of the single particle and the particle swarm.The kaolinite, one of the main mineral in slime water, has been chosen for study single slime particle zeta potential simulation with the influencing factors of different Ca2+Concentrations and pH values. Because kaolinite have different charge on different fracture surfaces,so the particle total-surface zeta potential model was established using the crystal cell number of different kaolinite fracture surface as weight and the model was used to simulate the kaolinite surface zeta potentials in different Ca2+concentrations aqueous solution, and using the electrophoresis test data to adjust the model. The results shown that the model could effectively predict kaolinite surface zeta potential when Ca2+concentrations more than25mg/L and pH less then9.In order to probe the zeta potential of the particle swarm, the zeta potential of coal slurry and clay slurry in the concentration of20±1g/L are measured in different pHs and Ca2+concentration by the mean of ESA (Electroacoustic Supersonic Amplitude) The results showed that with the increasing of Ca2+concentration, the fluctuation of kaolinite zeta potential has been intensify around PZC, the two PZC of quartz approached the range of pHs from8.32to8.77. When the Ca2+concentration is greater than0.86mmol/L and the pH decrease from4to2the zeta potential of montmorillonite was reduced due to the unit layer gathering to the larger particles,in addition, the adsorption of H+will lessen with the Ca2+concentration increasing. By compareing zeta potential of three types of clay slurry, three condition of coal slurry sedimentation are explained from the perspective of zeta potential and sedimentation situation, which include dispersion, network and half dispersion network, and the Ca2+concentration are0mmol/L,0<Ca2+<1.49mmol/L,>1.49mmol/L, respectively. Compared to others, network condition can get a clear clarification area.According to Coulomb principle, the settlement of charged particle in aqueous solution can accelerated by the applied electric field. In order to simulate the speed v and the displacement S of single slime particle settlement accelerated by the applied electric field, the dynamic equation has been established based on the force condition analysising of single particle in applied electric field and the simulation results was examined by the F and t examining methods, the results was shown significantly compared with electrophoresis test data correspondingly, the maximum deviation of v was4.57μm/s and the S was3.21μm.What’s more, the effection of influencing factors which can dominating the simulation results has been simulated and analyzed via the model, for example, the particle inherent nature and electric field factors. The simulation results show that the electric field assisted slime settling technology was suitable to the single particle which can satisfy the following conditions:the size was lower than0.015mm, the zeta potential was higher than30mV and the density was as higher as possible, also, the inter-electrode voltage should be as higher as possible in the range of the production cost and the electrical safety.The device which was set up by immersed iron electrode was used to probe the velocity of slime water settlement with the assistance of electric field and the experiment data was used to fitting. The results show that the transmittance of sedimentation clarification zone has been elevated, the zeta potential of slime water has been declined. What’s more, the power supply time shoudn’t to be maintained much too long,10min was the best; the voltage shoudn’t promote much too high,1kV was the best; the distance between electrode shoudn’t much too long,25cm was the best; the pH value should been lower than9. The flocculant was used to accelerating the settlement and the CaCl2was used to increasing the transmittance.