Title: Mobility of elements released from coal during CO2 sequestration

Authors: Changjiang Liu; Geoff Wang; Shuxun Sang; Huihu Liu; Kun Zhang

Addresses: Department of Petroleum Geology, China University of Petroleum (East China), Qingdao, Shandong 266580, China; Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China ' School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia ' School of Resource and Earth Science, China University of Mining and Technology, Xuzhou, Jiangsu 221008, China ' School of Earth Science and Environment, Anhui University of Science and Technology, Huainan, Anhui 232001, China ' School of Resource and Earth Science, China University of Mining and Technology, Xuzhou, Jiangsu 221008, China

Abstract: A key greenhouse emission reduction strategy is to sequestrate CO2 in the subsurface by injecting it into coal seams. We investigated the injection of CO2 into coal seams using static batch experiments conducted under similar temperature and pressure conditions to that of the formation from which the coal samples were originally obtained, in an effort to understand the mobilisation of elements released from the coal. Anthracite and high volatile bituminous coal samples (4-8 mm in size) were exposed to a solution of supercritical CO2 (ScCO2) and water at a temperature of approximately 40°C and a pressure of 9.8 MPa. The results obtained indicate that elements show different mobilities after exposure to the ScCO2-H2O solution. Their mobilities are mainly influenced by the occurrence of the elements in the coal minerals. It was found that the mobilisation of elements associated with carbonate minerals was greater than that of elements associated with sulphide and sulphate minerals; which was in turn greater than that of elements associated with silicate minerals. The results also show that close attention should be paid to the potential environmental hazards that might arise if the elements are released into groundwater systems during the CO2 sequestration process. [Received: December 16, 2015; Accepted: June 18, 2017]

Keywords: coal; elements mobility; CO2 sequestration; environmental hazard.

DOI: 10.1504/IJOGCT.2019.097450

International Journal of Oil, Gas and Coal Technology, 2019 Vol.20 No.2, pp.224 - 242

Available online: 22 Jan 2019 *

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