Study On The Influence Of Particle Morphology On The Performance Of Coal Water Slurry

Research on the influencing factors of coal water slurry performance at home and abroad mainly focuses on three aspects: slurry coal quality,particle size grading and additives.In addition,the existing particle size grading models are all stacking efficiency mathematical model derived by particle size and quantity calculating,where the influence of particle morphology factors is not considered.It cannot fully explain the effect of particle packing efficiency on slurry flow performance.Based on the exploring of characterization indexes and detection methods of particle morphology,this paper focuses on the influence of particle morphology factors on the performance of coal water slurry.The research content mainly includes: particle morphology characterization indexes and detection methods selecting;effect of crushing and grinding methods on coal particle morphology;effect of the morphological changes of narrow-grained particles on the performance of coal water slurry;effect of full-grainlevel shaping of vertical stirring mill on the performance of coal water slurry.This paper redefines the calculation method of the surplus particle accumulation efficiency,and establishes a mathematical model of coal slurry particle accumulation related to the particle morphology parameters,by drawing on the compressible accumulation model of the cement industry and introducing the circularity parameter of coal slurry particles.The main conclusions of this paper are as follows:1)The characterization index and detection method of coal particle morphology were optimized.It was found that the roundness and length to width ratio of the particles can reflect the morphology of the particles better.The dynamic particle image analyzer can quickly obtain the statistics of the morphological parameters of a large number of particles.2)By studying the effect of crushing and grinding methods on particle morphology,it was found that compared with the roller crushing method,the coal particles obtained by hammer crushing have a higher roundness and a smaller length to width ratio,especially in the 0.45-0.25 mm particle size segment,the morphological difference is obvious.Compared with the ball milling method,the particles obtained by rod milling are smaller in roundness and larger in length to width ratio,especially in the 0.25-0.15 mm particle size section,the particle shape difference is obvious.Through mechanism analysis,it is considered that rod milling is linear contact and ball milling is point contact.3)The experiment method of controlling variables was used to explore the influence of narrow-size-fraction particle morphology on the performance of coal water slurry.The narrow size-fraction of 0.25-0.15 mm was selected as the sample,and mixed with the fine pulp for slurry ability studying.The results showed that the apparent viscosity of the coal slurry decreases and the fluidity of coal slurry increases with the increase of the roundness of the 0.25-0.15 mm particle size and the decrease of the aspect ratio.4)Through the use of vertical agitating and grinding equipment for reshaping the full size-fraction of coal slurry,it was found that agitating and grinding can effectively improve the circularity of the coal particles and reduce the particle length to with ratio.The best working conditions in laboratory grinding and shaping are: grinding media of 6-6.5mm ceramic balls,stirring speed of 150 r / min,grinding for 5min.Therefore,this paper proposes a method for preparing high-performance coal-water slurry by optimizing full size-fraction particle morphology with vertical stirring mill as the core equipment.5)Based on the compressible accumulation model,industrial coal slurry particles were divided into five grades of 1.0-0.45 mm,0.45-0.25 mm,0.25-0.15 mm,0.15-0.075 mm,0.075-0mm and the roundness parameters of each grade were determined.Based on the parameters,the roundness parameter of the particles was introduced,the expression of the surplus accumulation efficiency was redefined,and the coal slurry particle accumulation model associated with the particle morphology parameters was established.The model can be used to further deduce the mathematical expressions of stacking efficiency and pulping concentration,which can be used for the prediction of industrial pulping concentration.