Industrial & Engineering Chemistry Research, Vol.35, No.11, 4257-4263, 1996
Gravity-Enhanced Magnetic (HGMS) Coal Cleaning
For economic and environmental reasons, precombustion magnetic coal cleaning must be performed on dry pulverized coal. Gravity-enhanced high-gradient magnetic separation has been successfully applied to the removal of mineral impurities from coal with a 4-T superconducting solenoid magnet. Under optimum separation conditions obtained in this study, this technique effectively cleans up to 72 wt % of the pyritic sulfur and 44 wt % of the ash content from a typical pulverized coal in a vertically upward airstream rig, and the heating value recovery is 95 wt %. Increasing applied magnetic fields and separator matrix lengths and decreasing superficial gas velocity each individually improve the cleaning performance. The results have indicated that the matrix made of 0.360-mm circular AISI 430 stainless steel wires is the best one for all the matrix grades used. These tests have paved the way for pilot plant trial runs at the power station site to be conducted.