利用冶金含铁固废制备多元掺杂型Fe基载氧体的基础研究

The mutil target components and high added uses of metallurgical solid wastes containing iron is the challenging problem due to the complexity of components. For the solid wastes have the characteristics of containing iron and other valuable elements，the studies is following：①simulating the Fe-sludge to prepare the sol system of Fe3+ and Al3+ contained Ca、Si、Mg as the research object, the degree of super saturation of Fe(OH)3 is deduced by determine activities of correlative ions and electric potential,and the macroscopic kinetics model of the target components is established.Systemic studies are performed to obtain the effects of reaction conditions on the structure and shapes of particles. Thus the control mechanism of precipitation of combination for the target components Fe(OH)3 and multi-metal-doped components can be clarified.②Furthermore,the Fe-base oxygen carrier material is fabricated by the coprecipitates and the effects of the structure and composition on Chemical-Looping Combustion are also examined via TG-MS.Therefore,the key scientific problems,which is the control of precipitation of combination for the target components,the growth mechanism of Fe(OH)3 and multi-metal-doped particles in the Fe-Ca-Si-Al-Mg system in the basic coprecipitation process and the mechanism of Fe-base oxygen carrier material in chemical-looping combustion,is resolved. Therefore we can not only provide the theory evidence of precipitation of combination for the target components in solid wasts,but also enrich solid waste recycling scientific connotation of high value-added and it is helpful to promote the research of low carbon emission in combustion technology, which has economic and environmental benefits.

冶金含铁固废复杂组分有效分离及高附加值利用是目前具有挑战性的课题。针对此固废具有大量铁和其它多种有价元素的特点，课题提出以此为原料，制备多元掺杂型Fe基载氧体材料思路，具体展开研究：①模拟冶金含铁固废成分合成含Fe3+和Al3+的Ca、Si、Mg溶胶体系，通过测定胶体电位和离子活度，建立目标粒子Fe(OH)3过饱和度的方法，系统研究反应条件对其结构和形貌的影响，阐明目标组分析出机制,并构建Fe(OH)3及掺杂粒子宏观生长动力学模型。②结合TG-MS及流化床燃烧等技术，分析目标产物所制备的掺杂型Fe基载氧体材料的结构特性及载氧能力，从而解决：“多元Fe-Ca-Si-Al-Mg体系中目标组分的掺杂析出、粒子生长机制以及其在化学链燃烧中的反应机制”的关键科学问题。预期成果将为冶金含铁固废多组分有效分离提供理论基础及技术依据，且有助于推动低碳排放燃烧技术的研究，具有一定的经济及环境效益。

基于目前钢铁冶金工业排放大量含铁固体废弃物未能实现高附加值利用，项目前期研究发现冶金含铁尘泥具有制备掺杂型Fe基载氧体的潜质，由于载氧体是化学链燃烧技术的关键，而化学链燃烧技术又是降低CO2排放的一项前沿技术，且目前全世界降低碳排放的问题已经迫在眉睫；项目通过对含铁固废的基本物理化学性质及模拟体系的共沉淀行为的研究，发现冶金尘泥浸出的反应浸出率受温度、盐酸浓度、浸出时间和液固比较为显著，通过正交试验，冶金尘泥中FCSAM体系最高浸出率达到89.82%。此外，实验发现由内扩散控制的未反应核模型适用于冶金尘泥模拟体系FCSAM在293-353K温度范围内浸出动力学研究；由拟合结果和计算得到反应的活化能为37.97kJ/mol。载氧体前驱体进行焙烧得到的掺杂型Fe基载氧体的外部形貌主要由棒状、球状以及块状颗粒组成，表面并无明显的颗粒物质；Al，Si和Ca的掺杂明显地提高了还原反应的反应速率和整体的反应速率；且负载惰性载体如SiO2、Al2O3及CaSO4的载氧体随着循环次数的增加，降低了烧结的概率，从而使得掺杂型Fe基载氧体的还原转化率在5周期循环内一直保持在较高且稳定性良好；在三种不同的还原气氛下，选取燃烧温度以及Fe析出率作为影响因素，结果发现Fe基载氧体受Fe浸出率的影响较为显著，呈现一次线性关系，与燃烧温度的关系呈现二次非线性关系。研究成果将为冶金高铁固废高附加值利用提供科学依据，其一般性规律将可应用于其它工业含铁复杂固废有价组分的高效利用，对指导以固废为主体的新型低廉高效的掺杂型Fe基载氧体的开发，降低CO2的污染具有重要的经济价值和环境意义。