The removal of pyritic sulfur from a Turkish lignite in aqueous suspension by nitric acid was investigated. The effects of particle size ( - 60, - 100 and - 200 mesh), reaction time (0 - 10 800 s), nitric acid concentration (5-30 wt.%), temperature (25-103 degreesC) and speed -of stirring (0.75-20 s(-1)) were studied. The pyritic sulfur was quantitatively removed at boiling temperature (approximate to103 degreesC in Erzurum) in 25% HNO3 solution. (C) 2002 Elsevier Science B.V. All rights reserved.