CO2 sequestration utilizing basic-oxygen furnace slag: Controlling factors, reaction mechanisms and V–Cr concerns

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 of0.5 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.     

钢渣吸附除磷性能的试验研究

研究了钢渣的吸附除磷效果并进行机理探讨。结果表明：钢渣采用0．5g,即可在25℃下、2个小时内,将100ml的磷浓度为10mg／L（以磷计）的模拟含磷废水的磷浓度降至0．5mg／L以下,达到磷的国家一级排放标准;钢渣吸附平衡时问为2小时;钢渣吸附除磷的机理主要是沉淀、吸附（表面络合反应）,并辅以静电作用。