| Vanadium slag is a blast furnace slag, which is point to containing vanadium molteniron blowing oxidation into a rich vanadium oxide and iron oxide by methods ofconverter. It is an important raw material of vanadium extraction. Due to the vanadiummainly occur in spinel phase by low valence form. So vanadium spinel phase wasdamaged and low valence vanadium of not easy soluble in acid was oxidized to highvalence vanadium of easy to soluble in acid, which were the premise condition ofvanadium extraction.The traditional methods of vanadium extraction were mostly the process ofroasting-leaching-heavy vanadium. It produced Cl2, HCl and other harmful gases in theprocess, which polluted environment seriously. Recently, the researchers proposed wetvanadium extraction （mainly acid leaching directly）. The method avoided effectivelyproducing HCl, Cl2waste gas. It caused pollution. But there were also someshortcomings （such as serious equipment corrosion, a lot of waste acid and lowvanadium leaching rate）. Therefore, looking for new vanadium extraction methods oflow pollution and high efficiency has become a problem, which to be solved in theglobal vanadium smelting industry.At present, wet leaching process was intensified by outside field （microwave field,ultrasonic field, electromagnetic field, etc）. It has been confirmed by many researchs. Atthe same time, the electro-oxidation has been extensively applied to treat copper sulfide,lead and zinc sulfide ore, bismuthinite, vulcanization silver, pyrite, and so on. Butelectro-oxidation applied to the study of vanadium slag leaching. There was noliterature report. Therefore, vanadium slag in Pan Gang Group Company, SichuanProvince in China was taken as the research object. According to vanadium slag objectphase was complex, many complex characteristics of vanadium forms and valence inthe vanadium slag. Put forward the study of vanadium slag leaching by electric fieldintensification. This paper mainly studied the following respects:①The experiments of vanadium slag acid leaching by electric field intensification.Effect of current, temperature, leaching agent concentration, time on vanadium leachingrate were studied by electric field intensification. The results showed that vanadiumleaching rate was79.64%acid leaching with MnSO4by electric field intensification.vanadium leaching rate was67.18%by direct acid leaching at an optimal condition of 40wt.%H2SO4, current0.6A, voltage2.83.0V，electrode spacing20mm，L/S4:1，m（vanadium slag:MnSO4）5:1, temperature of85℃and leaching time of4h. The mainreason was that object phaseis was not only destructed by electric field intensification,and low vanadium of not easily soluble in acid was oxidized to high vanadium of easyto soluble in acid by the effect of anode oxidation, so the leaching rate of vanadium wasimproved.②The experiments of vanadium slag alkali leaching pretreatment-acid leaching byelectric field intensification. Factors associated with pretreatment effect were studied,including NaOH concentration and CaF2quality. It showed that more pretreatmentsuitable condition was NaOH concentration10mol/L and m （vanadium slag:CaF2）5:1.In this condition, pretreatment slag was acid leaching again by electric fieldintensification, vanadium leaching rate was81.72%, improved25.21%compared withoriginal slag direct acid leaching at40wt%H2SO4, current0.6A, voltage3.13.3V,electrode spacing20mm, L/S4:1,85℃and2h. The main reason was that vanadiumspinel phase was packed by silicate phase. Silicate phase was destried by alkalineleaching pretreatment. So vanadium spinel phase was bared outer and facilitate tofurther damage.Then the leaching rate of vanadium was improved.③The experiments of vanadium slag selective leaching by electric fieldintensification. That vanadium slag was acid leaching with TBP and kerosene byelectric field intesification. It showed that vanadium leaching rate was49.83%at anoptimal condition of50wt%H2SO4, current0.8A, voltage3.84.0V, electrode spacing20mm,85℃,2h, L/S8:1, proportion of kerosene and TBP1:1and A/O ratio2.5.Vanadium leaching rate improved2.27%with TBP and kerosene by electric fieldintensification acid leaching compared with direct acid leaching, but iron leaching ratedecreased0.95%. Therefore, vanadium leaching better than iron in the TBP andkerosene systems, realize the selective leaching of vanadium slag. |
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