Tanaka Shunsuke, Takahashi Kosuke, Abe Masahiro, Noguchi Miyuki, Yamasaki Akihiro
Department of Materials and Life Science, Faculty of Science and Technology, Seikei University, 3-3-1 Kichijoji-kitamachi, Musashino, Tokyo 180-8633, Japan.
ACS Omega. 2022 Jun 1;7(23):19600-19605. doi: 10.1021/acsomega.2c01297. eCollection 2022 Jun 14.
A new type of mineral carbonation process for concrete sludge, a waste of fresh concrete under hydration, was developed, and the carbonation performances of the process were examined by laboratory-scale experiments. The process is composed of two steps; filtration of concrete sludge and bubbling of CO into the filtrate to form calcium carbonate. Model concrete sludge, a mixture of cement and water, was filtered through a cellulose filter after hydration for 24 h to obtain a solution containing dissolved calcium ions. Then, the model flue gas containing CO (10%) was bubbled through the filtrate solution, and calcium carbonate was precipitated by the carbonation reaction. About 3% of calcium in the concrete sludge could be extracted into the filtrate in a single filtration step, and more than 95% of dissolved calcium was recovered as calcium carbonate by the bubbling of CO. The obtained calcium carbonate was calcite with a high purity (>95%) and 5-10 μm. The solid residue (concrete sludge) after filtration was mixed with fresh water and filtered through a cellulose filter. Then, the model flue gas was bubbled into the filtrate solution for carbonation. This filtration-bubbling step was repeated 5 times, and 10.8% of calcium in the feed cement was extracted into the filtrates in total. More than 95% of the extracted calcium could be recovered as calcium carbonate with high purity (>97%), and the overall conversion of calcium in the feed cement to calcium carbonate was 10.1%. The purity of calcium carbonate and the calcium conversion were much higher than those for the direct bubbling method, where the model flue gas is bubbled into concrete sludge.
开发了一种针对混凝土污泥（水化作用下新鲜混凝土的废弃物）的新型矿物碳酸化工艺，并通过实验室规模的实验研究了该工艺的碳酸化性能。该工艺由两步组成：过滤混凝土污泥，然后向滤液中鼓入二氧化碳以形成碳酸钙。将水泥和水的混合物——模拟混凝土污泥在水化24小时后通过纤维素过滤器进行过滤，以获得含有溶解钙离子的溶液。然后，将含有10%二氧化碳的模拟烟道气鼓入滤液溶液中，通过碳酸化反应使碳酸钙沉淀。在单次过滤步骤中，混凝土污泥中约3%的钙可被提取到滤液中，通过鼓入二氧化碳，超过95%的溶解钙以碳酸钙的形式回收。所得到的碳酸钙为方解石，纯度高（>95%），粒径为5 - 10微米。过滤后的固体残渣（混凝土污泥）与淡水混合，再通过纤维素过滤器进行过滤。然后，将模拟烟道气鼓入滤液溶液中进行碳酸化。这个过滤 - 鼓泡步骤重复5次，进料水泥中总计10.8%的钙被提取到滤液中。超过95%的提取钙能够以高纯度（>97%）的碳酸钙形式回收，进料水泥中钙向碳酸钙的总体转化率为10.1%。碳酸钙的纯度和钙转化率远高于直接鼓泡法（将模拟烟道气鼓入混凝土污泥中）的情况。
