Separation performance of 0.5–1 mm fine coal in a gas–solid fluidized bed without dense medium

Abstract

The polluting elements in coal are mainly concentrated in gangue, and it is difficult for existing dry coal preparation technologies to separate fine gangue below 1 mm effectively. Because 0.5–1 mm raw coal particles belonging to the Geldart B group can form a stable bubbling fluidized bed, the fluidization and segregation of simulated coal particles composed of 0.5–1 mm quartz sand and clean coal were investigated in this study. The results showed that the optimum operation gas velocity was slightly higher than the minimum fluidization gas velocity when the content of quartz sand was less than 60%; when it was higher than 60%, the optimum gas velocity was somewhat less than or equal to the minimum fluidization velocity. When the content of quartz sand was 60%, the separation effect was the most obvious, and the segregation standard deviation was 0.37. The initial bed height was in the range of 150–210 mm, and the separation effect was good. In addition, the separation tests of three raw coal samples showed that the research results of binary-simulated coal particles composed of quartz sand and clean coal were valid. Under the optimal conditions, the ash content of clean coal products of three raw coal samples can be reduced by 75.65%, 79.03%, and 83.03%, respectively.