CO_2 sequestration utilizing basic-oxygen furnace slag:Controlling factors,reaction mechanisms and V–Cr concerns  

作　　者：Tung-Hsin Su Huai-Jen Yang Yen-Hong Shau Eiichi Takazawa Yu-Chen Lee 

机构地区：[1]Department of Earth Sciences,National Cheng-Kung University,Tainan 70101,Taiwan [2]Department of Marine Biotechnology and Resources,National Sun Yat-Sen University,Kaohsiung 80424,Taiwan [3]Department of Geology,Niigata University,8050,Ikarashi 2-no-cho,Nishi-ku,Niigata 950-2182,Japan [4]China Steel Corporation,1,Chung-Kang Rd.,Kaohsiung 81233,Taiwan

出　　处：《Journal of Environmental Sciences》2016年第3期99-111,共13页环境科学学报（英文版）

基　　金：sponsored by research funds from the China Steel Company 97T1F–RE038);the National Science Counsel(NSC-99-2116-M-006-013,NSC-100-2116-M-006-011-MY2)

摘　　要：Basic-oxygen furnace slag（BOF-slag） contains 〉35%CaO,a potential component for CO_2sequestration.In this study,slag-water-CO_2 reaction experiments were conducted with the longest reaction duration extending to 96 hr under high CO_2 pressures of 100-300 kg/cm2 to optimize BOF-slag carbonation conditions,to address carbonation mechanisms,and to evaluate the extents of V and Cr release from slag carbonation.The slag carbonation degree generally reached the maximum values after 24 hr slag-water-CO_2 reaction and was controlled by slag particle size and reaction temperature.The maximum carbonation degree of 71%was produced from the experiment using fine slag of〈0.5 mm under 100℃and a CO_2 pressure of 250 kg/cm^2 with a water/slag ratio of 5.Vanadium release from the slag to water was significantly enhanced（generally 〉2 orders） by slag carbonation.In contrast,slag carbonation did not promote chromium release until the reaction duration exceeded 24 hr.However,the water chromium content was generally at least an order lower than the vanadium concentration,which decreased when the reaction duration exceeded 24 hr.Therefore,long reaction durations of 48-96 hr are proposed to reduce environmental impacts while keeping high carbonation degrees.Mineral textures and water compositions indicated that Mg-wustite,in addition to CaO-containing minerals,can also be carbonated.Consequently,the conventional expression that only considered carbonation of the CaO-containing minerals undervalued the CO_2 sequestration capability of the BOF-slag by^20%.Therefore,the BOF-slag is a better CO_2 storage medium than that previously recognized.Basic-oxygen furnace slag（BOF-slag） contains 〉35%CaO,a potential component for CO_2sequestration.In this study,slag-water-CO_2 reaction experiments were conducted with the longest reaction duration extending to 96 hr under high CO_2 pressures of 100-300 kg/cm2 to optimize BOF-slag carbonation conditions,to address carbonation mechanisms,and to evaluate the extents of V and Cr release from slag carbonation.The slag carbonation degree generally reached the maximum values after 24 hr slag-water-CO_2 reaction and was controlled by slag particle size and reaction temperature.The maximum carbonation degree of 71%was produced from the experiment using fine slag of〈0.5 mm under 100℃and a CO_2 pressure of 250 kg/cm^2 with a water/slag ratio of 5.Vanadium release from the slag to water was significantly enhanced（generally 〉2 orders） by slag carbonation.In contrast,slag carbonation did not promote chromium release until the reaction duration exceeded 24 hr.However,the water chromium content was generally at least an order lower than the vanadium concentration,which decreased when the reaction duration exceeded 24 hr.Therefore,long reaction durations of 48-96 hr are proposed to reduce environmental impacts while keeping high carbonation degrees.Mineral textures and water compositions indicated that Mg-wustite,in addition to CaO-containing minerals,can also be carbonated.Consequently,the conventional expression that only considered carbonation of the CaO-containing minerals undervalued the CO_2 sequestration capability of the BOF-slag by^20%.Therefore,the BOF-slag is a better CO_2 storage medium than that previously recognized.

关 键 词：Mineral CO_2 sequestration BOF-slag Carbonation 

分 类 号：X701[环境科学与工程—环境工程]