钛白废酸无焙烧直接浸出提钒短流程新工艺及装备研究

A Novel Process of Leaching the Converter Vanadium Slag with Titanium Dioxide Waste and Equipment Research

钒钛磁铁矿是我国主要提钒资源,广泛地分布于我国的攀枝花、承德地区。以钠化焙烧—水浸为代表的焙烧浸出工艺存在着污染环境、金属回收率不高的问题,目前正被逐步改进。据统计每生产1 t钛白粉就会排出20%的废酸8-10 t,而中国钛白行业年产废硫酸达到600万吨,直接排放将造成严重的环境污染。该报告围绕无焙烧直接加压酸浸提钒技术中的直接加压酸浸、浸出液中有价元素分离、新型加压连续浸出反应器研发、系统内物流循环与利用、浸出渣的综合利用、工艺放大等研究内容进行,通过相关研究取得以下成果：（1）研究并对比了无焙烧常压酸浸、无盐氧化焙烧常压酸浸、无焙烧氧压酸浸3种提钒过程的现象,结果表明：相比无焙烧常压酸浸、无盐氧化焙烧常压酸浸等2个工艺,明显地具有反应快速、高效的特点。（2）采用硫酸体系加压浸出四川攀枝花地区的转炉钒渣,矿物学表明,转炉钒渣中的主要物相为尖晶石相、钛铁矿相以及铁橄榄石。加压浸出过程中,铁橄榄石和尖晶石相逐渐分解,钒、铁被浸出进入浸出液,部分未反应的钛、硅相在浸出渣中富集。（3）对该技术核心加压酸浸过程进行了放大实验研究,对实验室研究结果进行了验证,放大实验研究结果表明：钒的浸出率随着初始酸度的增加而增加,随着液固比的增大而增大。在加压温度150℃,硫酸浓度300 g/L,搅拌转速300 rpm,浸出时间90 min,液固比8∶1的条件下,钒的浸出率可达到99.10%。（4）提钒酸浸液萃取最优工艺条件为：常温,还原剂用量20 g/L、浸出液pH=2.0、有机相组成为20%P2O4,5%TBP,75%磺化煤油、相比（O/A）=1∶1、震荡时间5 min,钒的一级萃取率达到74.49%,Fe的萃取率仅为1.92%。在最优条件下,进行4级错流萃取,钒的总萃取率可达97.89%。以硫酸为反萃液进行反萃,其最优工艺条件为：反萃时间t=4 min、反萃液浓度200 g/L、反萃相比（O/A）=1∶1时,钒的反萃率达到98%以上。

As the major recourse for vanadium extraction, Vanadium-titanium magnetite is widely distributed in China Panzhihua, Chengde.area. The traditional technique of vanadium recovery from vanadium-containing minerals contains two key steps, roasting and water leaching. Meanwhile, low vanadium recovery and high energy consumption cause it can not be used in large-scale production. Currently, Sulfuric acid process is the main method for the production of titanium dioxide,during which the production of 1t titanium dioxide will generate 8-10 t waste sulfuric acid. In this study, the process of direct acid leaching without roasting, valuable elements separation, new pressurized continuous leaching reactor research,circulation of logistics system, leaching slag utilization and amplification technology have been researched. The results are as follow：（1）The process of atmospheric pressure leaching without roasting, none salt roasting with atmospheric pressure leaching and oxygen pressure leaching without roasting were researched. The results indicate that： compared with other process, the pressure acid leaching process has the advantage of respond quickly and efficiently characteristics.（2）The process of pressure leaching the vanadium slag by sulfate was research. It was found that spinel, fayalite and titanomagnetite are the main phase in the converter vanadium slag. The fayalite and spinel phase are gradually decomposed by sulfuric acid in the high pressure acid leaching process the unreacted silicon and titanium enrich in the leaching residue.（3）An enlarge experiment was researched. It was found that the leaching rate of vanadium increased with the acid concentration, and also increased with the liquid to solid ratio. Under the condition of 300 g/L sulfuric acid, 300 rpm, 90 min, 8∶1 liquid-solid ratio, at 90 min,the leaching rate of vanadium can reach 99.10%（4） At the experimental conditions of room temperature, the reducing agent20 g/L, the leaching solution p H=2.0, the organic phase consisting of 20% P2O4, 5% TBP, 75% sulfonated kerosene, phase ratio（A/O）=1∶1,shaking time 5 min, the extraction rate of V is 74.49%, the extraction rate of Fe is 1.92%. And the loss rate of vanadium is 1.39% after 4 level extraction at the optimal extraction conditions; Extract with sulfuric acid to stripping,the result shows that at the stripping time of 4 min、acid concentration of 200 g/L, phase ratio（A/O）=1∶1, stripping rate of vanadium is above 98%.