Su Tung-Hsin, Yang Huai-Jen, Shau Yen-Hong, Takazawa Eiichi, Lee Yu-Chen
Department of Earth Sciences, "National" Cheng-Kung University, Tainan 70101, Chinese Taipei.
Department of Earth Sciences, "National" Cheng-Kung University, Tainan 70101, Chinese Taipei.
J Environ Sci (China). 2016 Mar;41:99-111. doi: 10.1016/j.jes.2015.06.012. Epub 2015 Sep 5.
Basic-oxygen furnace slag (BOF-slag) contains >35% CaO, a potential component for CO2 sequestration. In this study, slag-water-CO2 reaction experiments were conducted with the longest reaction duration extending to 96hr under high CO2 pressures of 100-300kg/cm(2) 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 24hr slag-water-CO2 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 ≤0.5mm under 100°C and a CO2 pressure of 250kg/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 24hr. However, the water chromium content was generally at least an order lower than the vanadium concentration, which decreased when the reaction duration exceeded 24hr. Therefore, long reaction durations of 48-96hr are proposed to reduce environmental impacts while keeping high carbonation degrees. Mineral textures and water compositions indicated that Mg-wüstite, 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 CO2 sequestration capability of the BOF-slag by ~20%. Therefore, the BOF-slag is a better CO2 storage medium than that previously recognized.
碱性氧气转炉渣（BOF 渣）含有超过 35%的 CaO，是一种潜在的二氧化碳封存成分。在本研究中，进行了炉渣 - 水 - 二氧化碳反应实验，在 100 - 300kg/cm² 的高二氧化碳压力下，最长反应持续时间延长至 96 小时，以优化 BOF 渣的碳酸化条件，探讨碳酸化机制，并评估炉渣碳酸化过程中钒和铬的释放程度。炉渣碳酸化程度一般在炉渣 - 水 - 二氧化碳反应 24 小时后达到最大值，且受炉渣粒径和反应温度控制。在 100°C、250kg/cm² 的二氧化碳压力、水/渣比为 5 的条件下，使用粒径≤0.5mm 的细渣进行实验，产生了 71%的最大碳酸化程度。炉渣碳酸化显著增强了钒从炉渣向水中的释放（通常超过 2 个数量级）。相比之下，在反应持续时间超过 24 小时之前，炉渣碳酸化并未促进铬的释放。然而，水中铬含量一般比钒浓度至少低一个数量级，且在反应持续时间超过 24 小时时会降低。因此，建议采用 48 - 96 小时的长反应持续时间，以减少环境影响，同时保持高碳酸化程度。矿物结构和水成分表明，除含 CaO 的矿物外，镁方铁矿也可发生碳酸化。因此，仅考虑含 CaO 矿物碳酸化的传统表述低估了 BOF 渣约 20%的二氧化碳封存能力。所以，BOF 渣是一种比之前认为的更好的二氧化碳储存介质。
