基于矿相重构-溶液浸出条件下高硅冶金渣中含硅矿物的高效解离及演变规律

Desilicication is a traditional difficult problem in wet process for resources of high silicon metallurgical slag (and minerals). The essential reason lies in the existence of complex polymeric gel behavior of the dissolved silicate molecules in the leaching solutions. However, the concomitant silicic acid products polymerization and gelation during the subsequent valuable components precipitation process, which leads to difficulties of product purification and high value-added utilization. Based on the original exploration of direct extraction of target component in the slag, this project intends to use refractory high silicon metallurgical slag-Ti bearing blast furnace slag as the object of study and designed perovskite CaTiO3 in slag as the target component, the reconstruction of the silicon minerals and enrichment of valuable components in the target component are achieved by thermal modification methods with creating suitable physical and chemical conditions at the same time. SEM, ICP, and XRD techniques are used to illuminate the effect of composition, morphology and mineral phases of silicon minerals on the directed migration of water soluble “Si” and the acid soluble silicon minerals in solutions; to find out the interaction behavior for the reconstruction of silicon minerals and enrichment precipitation of target component; to clarify the hydrochloric acid leaching mechanism of Al、Mg and undissolved Si oxides in the slag using Shrinking Core Model(SCM). Finally, efficient separation of the target component and silicon minerals was realized in the high silicon metallurgical slag. The expected fruit can provide the theoretical principle and scientific basis of direct extraction of the target component in the Ti bearing blast furnace slag and establish a new method for direct materials utilization of the slag, therefore, the difficult problem of polymerization of silicic acid can be solved. Furthermore, there is important reference for resource of low grade high silicon metallurgical slag.

脱硅是高硅冶金渣(及矿物)湿法资源化过程中棘手的传统难题，其本质原因在于：溶出的硅酸分子在浸出体系中存在复杂的聚合胶凝行为。基于直接提取渣中目标组分的创新性探索，本项目以难处理高硅冶金渣-含钛高炉渣为研究对象，以渣中的钙钛矿CaTiO3为目标组分，通过创造适宜的物理化学条件对渣进行热态改性，同时实现含硅矿物的重构及有价组元"Ti"在目标组分的富集；查明含硅矿物重构与目标组分富集析出的相互作用；阐明含硅矿物的成分、形态及矿相组成对水溶性及酸溶性硅酸盐在溶液中定向迁移规律的影响；运用收缩核模型(SCM)，探明改性渣经水溶解浸出"Si"后，含硅矿物的酸解行为，揭示酸溶出硅酸聚合和目标组分解离的动力学控制机制，实现目标组分与含硅矿物的高效分离。预期成果不仅可为含钛高炉渣中目标组分的直接提取提供理论基础，开辟该类渣直接材料化新途径，破解硅酸聚合胶凝难题，且对低品位高硅冶金渣的资源化具有重要借鉴意义。

本项目针对宝贵含钛高炉渣资源化中的脱硅难题，设计渣中的钙钛矿CaTiO3为目标矿物，通过创造适宜的物理化学条件对渣进行热态改性，同时实现含硅矿物的重构及有价组元"Ti"在目标组分的富集；查明含硅矿物重构与目标组分富集析出的相互作用；阐明含硅矿物的成分、形态及矿物相组成对水溶性及酸溶性硅酸盐在溶液中定向迁移规律的影响；运用收缩核模型(SCM)，探明改性渣经水溶解浸出"Si"后，含硅矿物的酸解行为，揭示酸溶出硅酸聚合和目标组分解离的动力学控制机制，实现目标组分与含硅矿物的高效分离。获得如下重要原创性成果：1. 采用适当含氧酸钠盐对含钛高炉渣进行高温改性，不仅实现了渣中钙钛矿的富集、长大、析出，并且脉石矿物转化为可以完全溶于稀盐酸溶液的硅酸盐；2.本研究所采用的NaNO3、Na2SO4、NaOH、Na2CO3均能实现渣中钙钛矿的富集析出，考虑到环保等因素，优先使用30%的Na2CO3为宜； 3.后续湿法浸出，可实现硅酸盐的高效脱除（浸出渣中SiO2含量可低至1.3%），并且钙钛矿含量达85%左右；4. 通过实验判定酸浸过程符合核收缩模型，浸出过程受界面传质和固体产物层扩散混合控制，根据阿伦尼乌斯公式，求得Si的浸出表观活化能为18 kJ/mol。成果不仅可为含钛高炉渣中目标组分的直接提取提供理论基础，开辟该类渣直接材料化新途径，破解硅酸聚合胶凝难题，且对低品位高硅冶金渣的资源化具有重要借鉴意义。