Experimental Research On The Fluidization Characteristics And Separation Of Fine Kaolin In A Vibrated Dense Medium Fluidized Bed

In recent years,as the world's unique mineral resources,in-depth purification development and utilization of the hard coal series kaolin has gradually become the focus of scholars in various countries.Coal series kaolin through the purification,calcination,ultra-fine grinding and other deep processing can produce physical and chemical stability of high-grade filler and pigment grade products,which are widely used in papermaking,chemical,electrical,plastics,rubber composite materials and other industrial fields.In this paper,the vibrated dense medium fluidized bed(VDMFB)was used to study the desulfurization of 6-3mm and 3-1mm grain sizes natural coal series kaolin in Hebei Lingshou,and with 0.074-0.4mm ferrosilicon powder as the dense medium to separate coal series kaolin.The density of the ore is mainly distributed in the range of 1.9-2.7g/cm3 and the Loss on ignition(LOI)is 23.18% and 24.98% respectively.From the XRF data of the ore,it can be seen that the main constituent elements are Si and Al,in which the content of impurity element Fe is higher and the content of Ti is less.The fluidization characteristics of the air dense medium fluidized bed(ADMFB)and the vibrated dense medium fluidized bed were studied,it can be obtained that the vibration energy can significantly reduce the bed pressure drop ?P,the minimum fluidization gas velocity Umf and the bed expansion rate ?.With the increase of the vibration frequency,the bed pressure drop and the bed fluidization density(?p)decrease first and then increase.With the increase of the amplitude,the bed pressure drop and the bed fluid density have been reduced,the difference of fluidized bed density between different static bed height decreases with the increase of Hs.The introduction of vibration energy activates the movement of particles in fluidized bed,enhances the friction between gas and solid phases,effectively inhibits the formation and growth of bubbles in the bed,reduces the phenomenon of particles' adhesion in the fluidized bed,The bed pressure drop in the three-dimensional space of the bed is evenly distributed,forming a stable separation environment.The influence factors such as feed weight,vibration frequency(f),amplitude(A)and fluidization number(N)on the separation effect about 6-3mm and 3-1mm grain sizes coal series kaolin were studied,and the optimal range of single factor suitable for separating was determined.The orthogonal design of 6-3mm and 3-1mm grain sizes coal series kaolin was evaluated by using the central composite design response surface method(CCD-RSM),and the interaction between the operating factors was studied by the difference of loss on ignition,burnout ratio and total burn margin.Finally,the optimal evaluation indexes of the two kinds of grain size are determined as the total incineration of the concentrate and the loss of the concentrate respectively.At the same time,the quadratic polynomial prediction model corresponding to the evaluation index is established.For 6-3mm grain size coal series kaolin,the separation results shows that the yields of concentrate and tailing are 23.42%,and 23.39% and the loss on ignition are 21.91% and 28.93% respectively,and the difference ?X of the concentrate and tailings was 7.02% and the concentrate recovery rate was 22.80% when the Hs=100mm,f=15Hz,A=2.0mm and N=1.7.The yield of concentrate is higher,the loss of ignition is smaller,the total burning capacity is as high as 42.76%,and the ideal sorting effect is achieved.For the 3-1mm grain size coal series kaolin,the separation results shows that the yields of the concentrate and tailing were 10.73% and 25.92%,and the burn loss was 18.72% and 30.52% respectively,the concentrate recovery rate was 25.17%,and the difference in burn loss from fine tailings was 11.80% when Hs=100mm,f=15Hz,A=2.0mm and N=1.7.The yield of concentrate is higher,the loss of ignition is smaller,and the ideal sorting effect is obtained.