熔盐分解含钛高炉渣反应体系中有价组元相际转移规律及高效分离

The aim of project was enhance the recovery rate with titanium resources in the titanium-bearing blast furnace slag. The traditional acid process discharged a large amount of toxic waste, resulting in serious environmental problems, and the base process consumed a large amount of alkali and required a higher sintering temperature. A cleaning production process of low-temperature decomposition of titanium-bearing blast furnace slag was proposed. The aim of this process is to eliminate the pollution from the source and to fully utilize valuable compounds in titanium slag. The main points are as follows: A novel reaction system of molten salt and titanium-bearing blast furnace slag was established. By thermodynamic calculation, the possible products of the main compositions existed in titanium-bearing blast furnace slag were investigated in the decomposition process with molten salt. The kinetics, impact factors, variation of the crystal structure and migration of titanium in the molten salt reaction process were investigated. The recycle of molten salt reaction medium could be carried out by multi-stage countercurrent wash of molten reaction product and separation of impurities was studied. Process conditions and mechanism of hydrous titanium oxides by the thermal hydrolysis of titanium sulfate solution was investigated. The project provided a cleaning process for the cycle utilization and efficient decomposition of titanium-bearing blast furnace slag. The project had theoretical and practical significance on environmental problems by a large number of titanium-bearing blast furnace slag accumulation and waste of resources.

以全面提升含钛高炉渣中钛资源的回收率为目标，针对传统酸法工艺存在废物量大、毒性强、环境污染重及碱法工艺存在碱耗量大、烧结温度高等问题，本课题提出了低温熔盐分解含钛高炉渣的新体系，拟从生产源头消除环境污染，实现钛资源的高效-清洁-综合利用。重点研究包括：熔盐-含钛高炉渣反应新体系的构建，并通过热力学计算分析含钛高炉渣主要组分在熔盐中可能生成的产物；熔盐反应过程的工艺条件及动力学规律，包括反应过程中固相组元晶体结构的变化规律及钛的迁移规律；熔盐反应产物经多级逆流洗涤循环熔盐反应介质及杂质离子的高效分离；硫酸钛溶液低浓度水解制备偏钛酸工艺条件及机理。该项目对高炉渣的循环利用、高效分解提供新的"清洁"方法，对解决高炉渣大量堆积所带来的环境问题及资源浪费问题具有理论意义及现实意义。

针对传统酸法工艺存在废物量大、毒性强、环境污染重及碱法工艺存在碱耗量大、烧结温度高等问题，以全面提升含钛高炉渣中钛资源的回收率为目标，基于熔盐分解技术平台，提出氢氧化钠/氟化钠--含钛高炉渣反应新体系生产二氧化钛工艺，围绕含钛高炉渣新熔盐体系的构建、熔盐分解体系过程分析、分解过程元素迁移规律及高效分离等方面的展开研究工作。. 构建了氢氧化钠/氟化钠--含钛高炉渣反应新体系。通过热力学计算，对含钛高炉渣中的有价组元在新熔盐体系中分解情况进行分析，掌握钛及硅、铝组元的迁移情况。 以钛浸出率为目标，考察了反应温度、反应时间、碱渣比及含钛高炉渣粒度等影响因素，实现熔盐分解含钛高炉渣工艺条件的优化。结果表明NaOH:TBBFS= 3:1(质量比)），NaOH:NaF=3:1(摩尔比)，含钛高炉渣的起始粒度范围为45-75 μm，熔盐反应温度为500℃，实现钛浸出率达99%以上。作为有价组元钛，由含钛高炉渣中的CaTiO3相向Na2TiO3转变。但并没有Na2TiO3和Na4TiO4新相的生成。新生成相溶于稀酸。其它组分CaO、Na2TiO3、Ca(OH)2可溶于稀酸，而Na2SiO3可溶于热水。这为后续的浸出实验带来便利。可以在后续的实验中经过水洗、酸洗等简单步骤完成有价组元的纯化、杂质分离。 . 多级逆流洗涤再生反应介质氢氧化钠，实现反应介质内循环。同时根据熔盐反应产物中各元素在洗涤过程中的浸出行为差异。在实验考察的条件下，要保证钠离子的浸出率较高，同时目标元素钛的损失率在1%以下较为合理。最终确定洗涤温度50-55℃，液固比4:1，搅拌时间30min，可以实现钠离子的较高浸出却目标元素 钛的损失率较低。. 系统研究硫酸氧钛溶液水解制备偏钛酸过程。从产品纯度、水解率、粒度控制三个方面考察水解过程，实验结果表明总酸总钛比为15，TiO2的浓度为20g/L，所需酸浓度为300g/L，将水解后得到的偏钛酸洗涤合格后，920℃锻烧2h，得到平均粒度约为100nm，粒子球形度较好，粒度大小均匀金红石型TiO2。. 课题提出熔盐分解含钛高炉渣制备二氧化钛的清洁新工艺，这个生产工艺有两大突出优势：高效——钛转化率高达98%；清洁——酸碱介质的循环利用，废物废气排放量减少。拟从源头消除环境污染，实现钛资源有价组元的高效清洁综合利用。