Desulfurization of high sulfur fine coal using a novel combined beneficiation process

Abstract

The throughputof high-ash and high-sulfur fine-grain coal (0–6 mm) increases year by year. The seriousproblemof direct combustion is the formation of acid rain and smog. Therefore, the pre-combustion desulfurization and ash reduction can reduce environmental pollution. A combined process of dry separation and microwave desulfurization for the cleaning of the 0–6 mm fine coal was applied. The effectsofgas velocity, vibration amplitude and frequency on the removal ofinorganic sulfurwere analyzed systematically. At the same time, the effects of additives, microwave power, irradiation time and temperature on the removal of organic sulfur in the microwave desulfurization reactorwere investigated. The results show that the compounddry separator cansorts the 0–6 mm fine coal under the optimal operating parameters (A = 3 mm, f = 22.5 Hz, v = 0.68 m3/s). After the separation, the yield, ash and sulfur contents of the pre-separatedclean coalis 63.6%, 12.4% and 4.12%, respectively.The compounddry separatorcan effectively remove mineral impurities such as inorganic sulfur. The ash is reducedapparently.However,the organic sulphide cannot be removedby the separator. Asthe pre-separatedclean coal has high sulfur content thatis mainly organic sulfide, the microwave desulfurization reactoris used to remove this part of organic sulfur. The results show that the NaOH solution additive is more beneficial to improve the microwave desulfurization. The desulfurization rate increase with the increasing of temperature and radiationtime and the irradiation time has amore obviouseffect. After the microwave desulfurization the yield, sulfur and ash contents of the clean coal are60.8%, 0.98% and 9.74%, respectively. As a result, the microwave desulfurization processcan effectively remove the organic sulfur compounds.