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碱熔盐法处理直接还原钒钛渣回收钒和钛的研究
Alternative TitleRecovery of titanium and vanadium from titanium-vanadium slag obtained by direct reduction of titanomagnetite concentrates with alkaline molten salt method
刘雪洁
Subtype硕士
Thesis Advisor齐涛
2014-05
Degree Grantor中国科学院研究生院
Degree Discipline化学工艺
Keyword直接还原   含钒富钛渣   回收   氢氧化钠熔盐   钒   钛
Abstract我国超过85%的钒和90%以上的钛资源来源于钒钛磁铁矿,而传统工艺处理钒钛磁铁矿,钛、钒利用率低,近年来提出的直接还原工艺,提高了铁、钒、钛的综合利用率,得到含 TiO2 49%(以TiO2计,下同)、V2O5 1.2%以上的含钒富钛渣,能满足后续加工的质量要求。为了实现含钒富钛渣中钒/钛分离及分别提取利用的目的,本文利用本课题组提出的氢氧化钠熔盐法,展开了钒/钛分离及分别提取利用的工艺研究,重点研究了在氢氧化钠熔盐介质中含钒富钛渣的分解规律及晶型转化、水浸出过程钒/钛及杂质离子的走向,并初步探索了高浓碱液提钒的工艺研究。氢氧化钠碱熔盐法克服了传统硫酸法和氯化法制备钛白过程中的污染和对原料要求苛刻的问题。为含钒富钛渣的利用提供了一条新工艺,对钒钛磁铁矿中钛资源利用率的提高具有重要突破。本文的主要研究内容及结论如下: (1)在氢氧化钠熔盐作用下,将钒、钛分别转化为可分离的中间产物形式。通过XRD、SEM/EDS等交叉印证,确定了原料渣中主要物相结构。通过单因素实验-响应面法(RSM)优化考察了反应温度、碱渣质量比、反应时间对渣中钛、钒转化率的影响,结果表明,在优化的条件下,钛、钒的转化率分别达到96%和93%以上。通过XRD、SEM、TG-DSC表征,证实原料中黑钛石在438oC左右被分解生成不溶于水的Na2TiO3,钒转化为可溶于水的五价钒酸盐,同时,氢氧化钠将部分杂质转化为相应的钠盐形式,为钒钛及杂质分离奠定基础。 (2)熔盐反应产物经多级浸出,实现钒/钛分离。研究了浸出温度、浸出液固比、浸出时间对钒及杂质离子的浸出率,结果表明,在优化条件下经三级浸出后,93%以上的钒被浸出至碱液,而产物中的钛损失率小于1%,实现了钒/钛分离。同时杂质硅、铝、锰等部分浸出至碱液中,而杂质铁、钙、镁随钛进入固相水洗产物,实现杂质离子与钛的选择性分离。 (3)二氧化钛的制备及高浓碱液中钒的回收初步探索。研究水洗产物在硫酸介质中的溶出规律,钛溶出至酸液中,而杂质钙、硅等以固体的形式析出,实现钛与杂质二次选择性分离。研究钛液性质对偏钛酸制备的影响,将水解合格的偏钛酸煅烧制备出纯度98%,白度96的二氧化钛初品。初步探索高浓碱液中钒的回收技术路线,第一次提出钙沉-浸取-二次富集-钒产品的工艺路线。
Other AbstractMore than 85% of vanadium and 90% of titanium originate from titanomagnetite ores in China. However, the recovery efficiency of titanium and vanadium from titanomagnetites is very low by traditional treatment. Direct reduction process has been developed as an alternative in recent decades. The new route improves recovery efficiency of titanium and vanadium. A new type of titanium-vanadium slag containing TiO2 45%~50% and V2O5 1.5%~1.8% was obtained by the process and the slag could satisfy the quality requirement for subsequent treatment. To realize seperation and recovery of titanium and vanadium in titanium-vanadium slag, correspongding researche was carried out by NaOH molten salt roasting process developed by our laboratory. The paper mainly focuses on decompose behavior of titanium-vanadium slag and seperation of titanium and vanadium in water leaching process. A preliminary study about recovery of vanadium from high alkaline solution was also carried out. The main points are as following: (1) Titanium and vanadium in titanium-vanadium slag was coverted to intermediate products that could be seperated. The mineralogical phases were identified by XRD and SEM/EDS techniques. Effects of temperature, NaOH-slag mass ration and time on coversion of titanium and vanadium were investigated with single–factor experiment design combined with response surface methodology. More than 96% of titanium and 93% of vanandium were converted at the optimal conditions. XRD, SEM and TG-DSC were used to characterize the roasting process and the results show that MgxTi3-xO5 was converted to insoluble Na2TiO3 and vanadium was converted to water soluble vanadate. At the same time, impurities were converted to corresponding sodium salts partly. (2) Titanium and vanadium were successfully seperated through multi-stage water leaching. Effect of leaching temperature, solid-liquid ratio and time on leaching efficiency of vanadium and impurities were investigated. More than 93% of vanadium was leached out, while less than 1% of titanium dissolved in the solution. At the same time, Si, Al and Mn were partly leached out, while titanium and impurities of Fe, Ca and Mg remained in the solid intermediate. Therefore, titanium was initially separated from impurities selectively. (3) Preparation of TiO2 and exploratory experiments for recovery of vanadium from high alkaline solution were carried out. Release law of titanium from washing solid in H2SO4 was studied. Titanium dissolved in H2SO4, while impurities of Si and Ca precipitated from the titanyl sulfate solution, which realize second separation of titanium from impurities. Effect of concentration of titanyl sulfate on distribution of hydrous titanium oxides was investigated. TiO2 with approximately 99% of purity and Hunter white (Wh) 96 was obtained. Exploratory experiments for recovery of vanadium from high alkaline solution were carried out and the technique route for recovery of vanadium was first proposed, that is precipitation of vanadium from alkaline solution-leaching of vanadium residue-secondary enrichment of vanadium-vanadium product.
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/15565
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
刘雪洁. 碱熔盐法处理直接还原钒钛渣回收钒和钛的研究[D]. 中国科学院研究生院,2014.
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