Abstract:

A lot of alkaline-rich ash and slag wastes which are produced from calcium carbide production has the potential to capture and then mineralize CO₂. In this paper, the purified dust removed from the flue gas of a calcium carbide furnace was viewed as the research object and the deionized water was used as leaching agent. The influences of the mineralized reaction temperature, the volume fraction of CO₂, the liquid-to-solid ratio on the pH of the leaching solution from purified dust during CO₂ absorption process and the mineralization efficiency were studied. At the same time the reaction difference between direct mineralization and indirect mineralization was compared. The experimental results showed that the initial pH of mother liquor leached by deionized water from purified dust was about 12.7. The CO₂ mineralized product of purified dust was calcite with nanoscale diameter at 25 ℃. Enhancing the reaction temperature could shorten the required time for mineralization reaction. Meanwhile, it also promoted the formation of flower-shaped aragonite CaCO₃ and its particle grew in size. The mineralization reaction time became shorten through reducing the liquid-to-solid ratio and increased the volume fraction of CO₂. The efficiency for direct mineralization was close to about 60%, which was greatly higher than indirect mineralization efficiency. But the reaction time required for direct CO₂ mineralization was much longer than that for indirect CO₂ mineralization.

Key words: mineralization, CO₂, purified dusts, calcium carbide, leaching

摘要：

电石生产过程中会产生大量富碱性灰、渣废弃物，具有捕集和矿化CO₂的潜力。本文以某电石炉烟气脱除的净化灰为研究对象，以去离子水为浸取剂，对比研究了矿化反应温度、CO₂体积分数、液固比对净化灰浸取液吸收CO₂中pH和矿化效率的影响，同时也对比了湿法直接矿化和间接矿化的反应差异。实验结果表明，净化灰浸取母液的初始pH处于12.7左右，25℃矿化产物为纳米级方解石。提高反应温度，能够缩短矿化反应时间，促使花瓣状方解石型碳酸钙生成，同时碳酸钙颗粒粒径也会变大。降低液固比和提高CO₂体积分数也能缩短矿化反应时间。净化灰的CO₂直接矿化效率接近60%，明显高于间接矿化效率，但矿化反应时间却远长于间接矿化方式。

关键词: 矿化, 二氧化碳, 净化灰, 电石, 浸取