Study On The Effect Of Ultrafine Particles On The Properties Of Coal Water Slurry And Its Pulping Mechanism

The purpose of this paper is to reveal the mechanism of high-concentration coal slurry formation,focusing on such scientific problems as the change of the apparent characteristics of coal particles during ultra-fine grinding,the spatial distribution characteristics and interaction mechanism of multi-scale particles in high-concentration coal slurry,etc.,the experiments of slurry formation with wide particle size distribution,the representation of the apparent properties of ultrafine particles,the calculation of the interaction force between multi-scale particles,and the derivation of mathematical models have been carried out:(1)The best mixing ratio of fine slurry and ultra-fine slurry is 15%;First the coarse powder and the super fine pulp are mixed and kneaded,and then the additive is added,the slurry performance is the best;The performance of superfine pulp was the worst when the superfine pulp and additives were mixed first and then the coarse powder was added;A large number of ultrafine particles were coated on the surface of coarse particles in the skeletal image,and the number ratio of ultrafine particles between the surface of coarse particles and the gap was between 109-579.(2)With the decrease of particle spacing,the total potential energy between particles follows the law of "first positive and then negative,first increase and then decrease",and the critical point of change is 11μm.Coal particles less than 11μm are defined as ultrafine particles;In the process of pulping,a large number of ultrafine particles break through the "energy barrier" and adhere to the surface of the coarse particles,forming the coenobium water film structure.(3)Coarse particles can increase the solid content of coal slurry to improve the concentration,fine particles fill the gap between the coarse particles to improve the accumulation efficiency,and ultra-fine particles fill the gap and cover the surface of the coarse particles to reduce the sedimentation rate of the coarse particles and play a role in ball lubrication.By precisely controlling the size and proportion of fine and ultrafine particles,the slurry presents tight filling,dispersive adsorption-lubrication rheological characteristics;on this basis,the particle controlled concentration model was constructed,verified and modified.