This study focuses on the mineral carbonation to capture CO₂ using an alkaline industrial waste, the grits, formed during the kraft pulp production process. An indirect mineral carbonation route was adopted, composed by two steps: first the extraction of calcium from the grits and second the precipitation of calcium carbonate. Firstly, four solvents were analyzed (HNO₃, CH₃COOH, NaOH and NH₄Cl). Only HNO₃ and CH₃COOH have shown significant extraction efficiencies of 79.4 and 73.2%, respectively, after 2 h at 30 °C. Kinetic tests demonstrated that equilibrium conditions are reached after 60 minutes. Since the nitric acid is a corrosive acid and with high associated costs, the acetic acid was selected for the dissolution of grits and extraction of calcium. The optimal conditions determined were an acetic acid concentration of 2 M, solid/liquid ratio of 30 g/L and temperature of 45 °C with an efficiency approximately of 77%. In the second step, carbonation experiments were performed contacting the Ca-rich liquor, obtained from the extraction step, with a flux of pure CO₂ gaseous in a stainless inox reactor. The optimal conditions determined were 30 °C and 30 bar, reaching a carbonation efficiency of 74%, corresponding a CO₂ sequestration capacity of 460 kg CO₂/ton of grits.

这项研究的重点是利用牛皮纸浆生产过程中形成的碱性工业废料即沙粒，将矿物碳酸化以捕获CO ₂。采用间接矿物碳酸化路线，包括两个步骤：首先是从粗砂中提取钙，其次是碳酸钙的沉淀。首先，分析了四种溶剂（HNO ₃，CH ₃ COOH，NaOH和NH ₄ Cl）。仅HNO ₃和CH ₃在30°C下放置2 h后，COOH的萃取效率分别为79.4％和73.2％。动力学测试表明，在60分钟后达到平衡条件。由于硝酸是腐蚀性酸，且相关成本较高，因此选择乙酸用于砂砾的溶解和钙的提取。确定的最佳条件是乙酸浓度为2 M，固/液比为30 g / L，温度为45°C，效率约为77％。在第二步中，进行了碳酸化实验，使从萃取步骤获得的富含Ca的液体与纯净的CO ₂流量接触在不锈钢Inox反应器中呈气态。确定的最佳条件是30°C和30 bar，碳酸化效率达到74％，对应的CO ₂截留能力为460 kg CO ₂ /吨粗粉。