Study On Separation Behavior And Motion Characteristic Of Particles In Liquid-Solid Fluidized Bed Separator

Liquid-solid fluidized bed separator, as one of the most effective coarse coal slimeseparation, has been widely used in many coal preparation plants at home and abroad. It is ofgreat theoretical significance for further development and innovation of the liquid-solid fluidizedbed separation technology to study separation behavior and movement characteristics of solidparticles in liquid-solid fluidized bed. In this thesis, based on setting up the improved liquid-solidfluidized bed separation system and studying the liquid-solid fluidized bed separation theory,experimental study and numerical simulation is carried out for particulate fluidizationcharacteristics and coarse coal slime separation characteristics and high speed dynamic analysissystem is used to study kinetic characteristic of solid particle in the process of sorting. Theconclusions are drawn as following.The particles of different density and size have different initial fluidization velocity which isequal to settling velocity on numerical. The initial fluidization velocity increase with the increaseof the density and particle size. Different bed expansion characteristics come out when the risingwater velocity is different. The lower the initial fluidization velocity, the higher bed expansiondegree. When different density particles are fluidized, the particles layer by the density innarrow grain size, but blend or layer by the size in more and more wide grain size. It is proposedby tests that when the lower limit of0.25mm in fluidized bed separation, particles of>1mmshould be avoided into the separator to ensure the sorting accuracy.The velocity of transient liquid phase at different heights is analyzed in the process ofliquid-solid fluidized bed of coarse coal slime separation. And the relationship of the velocity oftransient liquid phase and apparent water velocity and particle loose is derived as follows:Vdh=Qu/dhθS·=VS/θdh=VS/1-λdhThe paper indicate that Instantaneous flow rate at the bottom of the cylinder is higher thanthat at the upper of the cylinder. The study concludes that the concentration of the particle phasedistribution at the bottom is in high concentration and the upper is in low concentration on thewhole, and particle concentration at material inlet is higher than that at the near area. The contentof high density particles is lower and lower as column height increase, while the content of lowdensity particles is gradually higher. Eventually it leads to the reducing bed density constitutedby particles and fluid with the increase of height. The density presents gradient variation and itincrease slightly at material inlet and will continue to reduce latterly. In the process of separating, the ash of coarse slime presents cascade distribution of high bottom and low upper in bed height.The paper elicits the function expression regarding with bed density, particles loose degree andParticle composition properties.ρdh(v,h)=λdh(v,h)(Σi(v,h)δi(v,h)-1)+1When particle density is different, the kinetic characteristics of particle in the liquid-solidfluidized bed is different. On the whole, low density particles move up while high densityparticles down, and middle density particles stay in the middle of the bed. The study concludesthat instantaneous velocity of single particle is constantly changing and fluctuates in a certainrange. The fluctuating of velocity conform to the law of normal distribution. The averagefluctuating is close to the average velocity of similar particle group in the same area.The result of separating of coarse slime of Gu Cheng coal preparation plant in Lin YiMineral bureau has been integrative optimized. Clean coal yield of product is71.52%, clean coalash is6.87%, combustible material recovery is82.26%and recovery efficiency is91.77%at theoptimum operating parameters combination. The thesis proposes an innovative technique on thecombination of liquid solid fluidized bed separator and micro-bubble flotation column is used tore-separate middlings resulting in a new idea in improving clean coal yield in coal preparationplant.