Abstract

BARRAZA, Juan  and  MEJIA, Isabel. Ultraclean coal production using froth flotation and acid leaching. Rev.fac.ing.univ. Antioquia [online]. 2009, n.49, pp.50-60. ISSN 0120-6230.

Ultraclean coals represent an important raw material to elaborate high value products such as carbon fiber, electrodes, carbon foam and so on. In this work, ultraclean coals having less than 0.50% (w/w, db) of ash and 1.00% θ(w/w) of mineral matter were obtained using flotation column and leaching with acid fluorhídric (HF) and nítric (HNO₃). Ash content was reduced from 19.60 to 8.70 %, using three flotation stages. Chemical processing, using HF 7.53 M and HNO₃ 2.30 M, produced 1.42% of ash content, 0.86 % of sulphur and 2.00% of mineral matter, whereas a combined process, froth flotation followed by leaching of HF 19.2M and HNO₃ 8.12M produced a coal having 0.48 % of ash content, 0.71% of sulphur content and 0.96% of mineral matter. However, when it was used the original coal (unfloated) at the same acid conditions of the combined process, it was obtained an ultraclean coal having 0.33% of ash content.

Keywords : ultraclean coal; froth flotation; acid leaching.