Jie Sha

A Design of an Inclined Froth Zone in Column Flotation Device to Reduce Ash Content in Clean Coal

A modified column flotation was designed based on the cyclonic microbubble flotation column (FCMC). In the modified flotation column, the froth zone was designed with an inclined arrangement to enhance the gravity settling of coarse middling particles, which were collected as a third product. The modified flotation column was referred as S-FCMC. In this study, the effects of process parameters (collector dosage, frother dosage, superficial gas velocity, and froth layer height) on the performance of the S-FCMC were investigated. For comparison purposes, tests were also conducted using the standard FCMC. The results showed that clean coal obtained using the S-FCMC had lower ash content than that obtained with the FCMC. Under the optimized operating conditions, the decrease in clean coal ash content and clean coal yield was 1.29% and 3.93%, respectively. The increase in tailings ash content and flotation efficiency index was 6.77% and 1.57%, respectively. About 64.55% of the settled (third) product in the inclined zone consisted of −0.045 mm sized particles and the ash content of this size fraction was 58.04%.

Hydrodynamics of Coarse Coal Slime and Quartz Particles in a Liquid-Solid Fluidized Bed Separator

The hydrodynamics of particles of coarse coal slime and quartz of different sizes in a liquid-solid fluidized bed separator were investigated experimentally, including minimum fluidization velocities, bed expansion ratios, and segregation of mixed particles with two methods. Experimental parameters studied included density and size of particle, superficial water velocity and initial static bed height. The results provide a reference for choice of size scope on coarse coal slime separation by liquid-solid fluidized bed separators.

Separation of 0.75-0.125 mm Fine Coal Using the Cylindrical Section of a 710/500 mm Three-Product Dense Medium Cyclone

ABSTRACT Dense medium cyclone is effective in beneficiation of fine coal with great separation precision. Small-diameter cyclones (usually 150 mm to 350 mm) are preferred in industrial applications. But the handling capacity of a small cyclone is low, which brings about the problems of maintain and operation. The separation efficiency of large-diameter cyclones with greater handling capability in fine coal treatment is questionable. In this study, the cylindrical section of a 710/500 mm three-product cyclone was adopted to treat 0.75–0.125 mm fine coal, where the cylinder-cone cyclone was a surge section. Influence of inlet pressure and feed rate were studied in an industrial environment. According to the results, the separation efficiency was sharp at relatively low feed pressures (110 KPa to 160 KPa). The separation effect increased with the feed rate. The favorable Ecart probable (Ep) value of 0.054 was obtained at an inlet pressure of 120 KPa and a feed rate of 42 t/h. Results of the studies showed that large-diameter cyclones will be applicable for fine coal treatment. These results will be significant for fine coal with a high content of near-density material.

Comparison of Separation Performance of Liquid-Solid Fluidized Bed Separator and Dense Medium Cyclone for Cleaning Coal

ABSTRACT Both a liquid-solid fluidized bed separator (LSFBS) and a dense medium cyclone (DMC) are used for cleaning coal of -1+0.25 mm size. However, a comparison of LSFBS and DMC’s performance in separation of difficult-to-separate coal has seldom been reported. Difficult-to-separate coarse coal from the Tangkou plant was processed using LSFBS and DMC. The products with the same ash content were analyzed by the float-sink tests to compare the separation efficiencies. According to the results, the concentrate yield and Ep value obtained by the DMC were 48.85% and 0.045, respectively, while the values obtained by LSFBS were 32.86% and 0.12, respectively. The results showed that DMC was more efficient than LSFBS for separating the Tangkou difficult-to-separate coal with a higher yield and a lower Ep value.

Comparative Study of Separation Performance of a Spiral and Dense-medium Cyclone on Cleaning Coal

Spiral separators and dense-medium cyclones (DMCs) are widely used for separation of −1 + 0.125 mm fine coal. In this study, testing was carried out using −1 + 0.125 mm fine coal with low near dens...

Overview of Typical Coal Flotation Flowsheets in China’s Coal Preparation Plants

The entrainment of high-ash fine slime severely contaminates clean coal product of traditional flotation cell, leading to serious technical problems such as high ash in clean coal, low recovery, and the sacrifice of the yield of gravity separation to lower the ash content of final product. In order to solve those issues, the performance of FCMC series cyclonic microbubble flotation column and traditional flotation cell were compared. Several typical flowsheets for the separation of coal flotation in China’s coal preparation plants (CPPs) were extensively reviewed and deeply explored. Results show that FCMC flotation column is especially suitable for the beneficiation of fine and non-selective coal slime downstream the heavy medium separation. The mixed (one-stage) flotation process utilizing the combination of flotation column and clean coal quick-operating pressure filter is recommended in newly built and retrofitted CPPs. As for those utilizing one-stage flotation flowsheet equipped with traditional flotation cell and pressurized filter, either classified flotation process or secondary flotation for the filtrate of pressurized filter using flotation column and clean coal quick-operating pressure filter is recommended in their technical modifications.