Lee Han, Peng Yen-Ling, Whang Liang-Ming, Liao Jiunn-Der
Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan.
Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan.
Materials (Basel). 2021 Jun 9;14(12):3187. doi: 10.3390/ma14123187.
Steel slag is a secondary product from steelmaking process through alkaline oxygen furnace or electric arc furnace (EAF). The disposal of steel slag has become a thorny environmental protection issue, and it is mainly used as unbound aggregates, e.g., as a secondary component of asphalt concrete used for road paving. In this study, the characteristics of compacted porous steel slag disc (SSD) and its application in phosphorous (P)-rich water filtration are discussed. The SSD with an optimal porosity of 10 wt% and annealing temperature of 900 °C, denoted as SSD-P (10, 900) meets a compressive strength required by ASTM C159-06, which has the capability of much higher than 90% P removal (with the effluent standard < 4 mg P/L) within 3 h, even after eight filtration times. No harmful substances from SSD have been detected in the filtered water, which complies with the effluent standard ISO 14001. The reaction mechanism for P-rich water filtration is mediated by water, followed by two reaction steps-CaO in SSD hydrolyzed from the matrix of SSD to Ca and reacting with PO. However, the microenvironment of water is influenced by the pH value of the P-rich water at different filtration times and the kind of P-rich water with different free positive ion that interferes the reactions of the release of Ca. This study demonstrates the application of circular economy in reducing steel slag deposits, filtering P-rich water, and collecting Ca(PO) precipitate into fertilizers.
钢渣是通过碱性氧气转炉或电弧炉（EAF）炼钢过程产生的副产品。钢渣的处置已成为一个棘手的环境保护问题，它主要用作松散集料，例如用作道路铺设用沥青混凝土的次要成分。在本研究中，讨论了压实多孔钢渣盘（SSD）的特性及其在富磷水过滤中的应用。孔隙率为最佳的10 wt%且退火温度为900℃的SSD，记为SSD-P(10, 900)，满足ASTM C159-06要求的抗压强度，即使经过八次过滤，它在3小时内去除磷的能力也远高于90%（出水标准<4 mg P/L）。过滤后的水中未检测到来自SSD的有害物质，符合出水标准ISO 14001。富磷水过滤的反应机制由水介导，随后是两个反应步骤——SSD中的CaO从SSD基质水解为Ca并与PO反应。然而，水的微环境受不同过滤时间富磷水的pH值以及含有不同游离阳离子的富磷水种类影响，这些游离阳离子会干扰Ca释放的反应。本研究展示了循环经济在减少钢渣堆积、过滤富磷水以及将Ca(PO)沉淀物收集制成肥料方面的应用。
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