微波强化铵盐浸出冶金废渣及碳酸化固定二氧化碳的机理研究

In order to curb global warming, the indirect aqueous carbonation of metallurgical waste slags has better application prospect to fix carbon dioxide and produce calcium carbonate. It is of great significance for carbon dioxide emission reduction of the iron and steel enterprises and calcium carbonate manufacturers, as well as resource and value-added processing of metallurgical waste slags. However, lower leaching rate of calcium ion in the leaching period and high concentration of impurity ions in the leaching solution in indirect aqueous CO2 carbonation process as well as lack of basic theory in the ammonium leaching systems are urgent problems required to be solved. The applicant found that calcium in the waste slags can be selective leaching during the leaching stage when the ammonium salts were used as a leaching agent, and the usage of microwave technology can effectively enhance the chemical reactions. In this project, the leaching and precipitation thermodynamics of calcium and magnesium ions in the complex ammonium salt systems would be studied in order to guide the microwave strenthening leaching of metallurgical slag process which use the ammonium salt as a leaching agent. The leaching reaction mechanism is also investigated. In addition, the relationship of precipitation parameters of calcium carbonate, product form and conversion rate of calcium carbonate, as well as the precipitation kinetics mechanism of calcium carbonate in a microwave field are studied. Moreover, the key technical parameters such as recycling ratio of leaching medium and energy consumption are also explored. The theoretical and experimental basis are, therefore, provided to fit in with the CO2 source reduction in the iron and steel enterprises and reclamation and value-added processing of metallurgical waste slags.

为了遏制全球变暖趋势，采用冶金废渣间接湿法工艺固定CO2同时生产碳酸钙是一种应用前景较好的矿物碳酸化固定CO2工艺，对钢铁企业和碳酸钙生产企业CO2减排以及冶金废渣资源化和增值化处理都具有重要意义。但间接湿法碳酸化固定CO2工艺中浸出阶段Ca2+浸出率不高、浸出液中杂质离子浓度高、铵盐浸出体系基础理论缺乏等都是迫切需要解决的问题。申请人发现在浸出阶段采用铵盐作为浸出剂可以选择性的浸出钙，且采用微波技术可以有效促进化学反应进行。本项目拟研究复杂铵盐体系钙镁等离子浸出和沉淀热力学理论基础，用于指导微波强化铵盐浸出冶金废渣，探明浸出反应动力学机理，并揭示微波强化碳酸化反应阶段碳酸钙沉淀条件与产物形态和碳酸钙转化率的影响规律以及沉淀动力学机理，探索浸出介质的循环再利用及能耗等关键技术参数，为配合钢铁企业CO2源头减排和冶金废渣资源化和增值化处理提供理论和实验依据。

为了遏制全球变暖趋势，采用冶金废渣间接湿法工艺固定CO2同时生产碳酸钙对钢铁企业和碳酸钙生产企业CO2减排以及冶金废渣资源化和增值化处理都具有重要意义。本项目旨在完善铵盐浸出体系基础理论，并采用微波辅助浸出手段，从而解决间接湿法碳酸化固定CO2工艺中浸出阶段Ca2+浸出率不高、浸出液中杂质离子浓度高的问题，同时探究微波场中铵盐体系浸出废渣中钙及碳酸钙沉淀反应机理，为钢铁企业实现CO2减排，以及冶金废渣的资源化和增值化利用提供理论依据。主要开展了如下研究工作：（1）铵盐体系中钙镁离子浸出和碳酸化过程中的理论基础；（2）冶金废渣所含主要元素赋存形式及浸出体系在微波场中的升温和电导行为；（3）微波强化浸出过程中工艺参数对主要元素离子浸出的影响规律、反应动力学机理和模型；（4）微波强化铵盐浸出冶金废渣的内在机制；（5）微波场作用下工艺参数对体系中碳酸钙形成的影响规律及沉淀动力学机理；（6）模拟尾气条件下微波作用铵盐体系中碳酸钙的制备；（7）微波强化铵盐浸出冶金废渣固定CO2工艺中关键技术参数的探讨及工艺应用潜力评估。