Study On Experiment Of Low Density Fine Coal Separation By Pulsed Fluidized Bed

Dry coal beneficiation technology could over come the limit of water in separation process, owning wide application prospect. Due to the widespread use of fullmechanized coal mining technology, fine coal content in raw coal is constantly rising. Even through traditional air dense heavy medium can be used to separate-50+6mm coal,-6mm coal cannot be separated effectively. Pulsed fluidized bed is able to diperse and segregate-6mm coal according to its density differences effectively. However, with the increase of clean coal product quality, conventional heavy medium for pulsed fluidized bed cannot form uniform and stable low density fluidized medium layer, thus low ash clean cannot be separated out. This paper aims at study material and constitution of low density heavy medium for pulsed fluidized bed as well as suitable operating parameter range.In this subject, pulverized coal cannot be used as one of the material for regulating magnetite heavy medium density in pulsed fluidized bed, after investigating the fluidization characteristics of magnetite powder and pulverized coal with different grain size as well as its mixture binary heavy medium fluidization properties and mixing and segregation characteristics.In addition, by experiment research, material constitution for pulsed fluidized bed low density heavy medium is-0.15+0.074 mm magnetite powder and-0.25+0.15 mm quartz sand. Influence regulation of operation airflow velocity, pulsation frequency and quartz mass fraction for bed layer average density and density stability are acquired after single and 3 factors orthogonal experiment. Pulsed fluidized bed layer will be lower average density when quartz mass fraction of binary heavy medium is 40%-50%, airflow velocity is between 7.87-9.83cm/s range and pulsation frequency is 3Hz-4Hz.The effect weight and interaction of operation airflow velocity, pulsation frequency and quartz mass fraction for bed layer average density are obtained: C(mass fraction)>A(airflow velocity)>B(pulsation frequency); AC(airflow velocity× mass fraction) > BC(pulsation frequency× mass fraction)>AB(airflow velocity× pulsation frequency). Bed layer density will decrease with the increasing of quartz sand mass fraction, decrease first and then increase gradually with the increasing of airflow velocity, increase first then decrease with the increasing of pulsation frequency. The approximation formula of bed layer average density is: density=8.38632-0.56439A-0.27193B-0.16858C+2.99142×10-3AB+4.46853×10-3AC+1.17862×10-3BC+0.019583A2+0.029867B2+1.26000×10-3C2In this formula, density means bed layer average density, A represents airflow velocity, B is pulsation frequency, C represents quartz sand mass fraction of binary heavy medium.-6+3mm jet coal of a Xinjiang coal mine is used for separation experiment by obtained binary heavy medium. The results show that the binary heavy medium consists of-0.15+0.074 mm magnetite powder and-0.25+0.15 mm quartz sand can achieve clean coal low density beneficiation under appropriate operating parameters.Besides in this paper, the separation and recovery technology is also explored briefly, quartz sand and magnetite powder can be recovered effectively by screeningdry magnetic separation-pulsed fluidized bed process.With the aid of Fluent software stimulating planar pulsed fluidized bed fluidization process and high speed dynamic system shooting, quartz sand- magnetite powder particle motion rule, bed layer density distribution law and bubble motion rule are all verified further.Material and constitution of low density heavy medium for pulsed fluidized bed as well as suitable operating parameter range is achieved and verified in this paper by means of experiment study and simulation, offering effective process technology for dry coal beneficiation low ash fine coal product.