| Title: | In Situ Capturing and Absorption of Sulfur Gases Formed during Thermal Treatment of South African Coals |
| Author(s): | Matjie RH; Lesufi JM; Bunt JR; Strydom CA; Schobert HH; Uwaoma R; |
| Address: | "Centre of Excellence in Carbon-Based Fuels, School of Chemical and Minerals Engineering and Centre of Excellence in Carbon-Based Fuels, School of Physical and Chemical Sciences, North-West University, Potchefstroom 2520, South Africa. Chemical Engineering - Faculty of Engineering & Technology, Vaal University of Technology, Vanderbijlpark Campus, Vanderbijlpark 1911, South Africa. The EMS Energy Institute, Penn State University, University Park, 16802 Pennsylvania, United States" |
| ISSN/ISBN: | 2470-1343 (Electronic) 2470-1343 (Linking) |
| Abstract: | "The objective of this study, the first of its kind on these specific South African low-sulfur coals, was to capture H(2)S and SO(2) produced under inert and oxidizing conditions from sulfur compounds present in the coals. The capturing agents were calcium and magnesium oxides formed during the transformation of calcite and dolomite. The effectiveness of two different scrubbing solutions (0.15 M cadmium acetate and 1.1 M potassium hydroxide) for absorption of volatilized H(2)S and SO(2) was also investigated. The bituminous coal (coal A) contained dolomite, calcite, pyrite, and organic sulfur. Lignite (coal B) had a high organic sulfur content and contained gypsum, no or low dolomite and pyrite contents, and no calcite. A third sample (coal C) was prepared by adding 5 wt % potassium carbonate to coal A. Under oxidizing conditions and at elevated temperatures, FeS(2) produced Fe(2)O(3), FeO, and SO(2). It transformed to FeS and released H(2)S under inert conditions. Organic sulfur interacted with organically bound calcium and magnesium at 400 degrees C in an inert atmosphere to form calcium sulfate and oldhamite ((Ca,Mg)S). CaO, produced from calcite or dolomite, reacted with SO(2) and O(2) at 950 degrees C to form calcium sulfate. Treatment of lignite at 400-950 degrees C resulted in 96-98% evolution of sulfur as gases. Hydrogen sulfide formation increased with the increasing thermal treatment temperature under inert conditions for the three coals. Under oxidizing conditions, sulfur dioxide formation decreased with the increasing temperature when heating coals B and C. The lowest ratio (0.01) of H(2)S to SO(2) was achieved during thermal treatment of the blend of coal and potassium carbonate (coal C), implying that almost all of sulfur was retained in the coal C ash/char samples. In situ capturing of sulfur gases by CaO and MgO and by the added K(2)CO(3) in coal C to form calcium/magnesium/potassium sulfates and potassium/calcium/magnesium aluminosilicate glasses during utilization of these and similar coals could reduce the percentage of sulfur volatilized from the coals by 54-100%, thereby potentially decreasing their impact on the environment" |
| Notes: | "PubMed-not-MEDLINEMatjie, Ratale H Lesufi, Jeanett M Bunt, John R Strydom, Christien A Schobert, Harold H Uwaoma, Romanus eng 2019/08/29 ACS Omega. 2018 Oct 26; 3(10):14201-14212. doi: 10.1021/acsomega.8b01359. eCollection 2018 Oct 31" |
