A Novel Process For Extracting And Preparing Vanadium Products From Stone Coal Acid Leaching Solution

Vanadium palys an important role in the fields of iron and steel, chemical and otherassociated industries. China has an abundant resource of vanadium ore, and the vanadiumextraction from stone coal has been an important research subject from1960s. The disadvantagessuch as the low metal recovery rate and the serious environmental pollution make the use oftraditional stone coal vanadium process limited, and this makes it a hot point on stone coalvanadium researching in the other hand. So far, the solvent extraction and the ion exchange aretwo general methods on vanadium sparation and preconcentration from leaching solution.However, there are some problems, such as process complication, strict demand in operation andthe heavy interference of impurities for the purify process, in using these methods, and these makethem limited in their industrial applications.In this paper, in order to solve the problems above, anovel technological process, the leaching by sulfuric and aid leaching agent, decontaminate bycrystallization, vanadium precipitate, precipitation alkaline roasted, leaching, alkaline leachingmake vanadium precipitate technological process has been propose.Result of the leaching procedure shows that the leaching rate is low with the method ofextracting vanadium by using sulfuric directly leaching from stone coal, which is less than55%.The leaching rate can be sharply increased by adding HF. Under the condition of leachingtemperature90℃, H2SO4amount40%, leaching time12h, liquid-solid ratio1:1and aid leachingagent amount8%, the vanadium extraction yield is from53.5%to88.4%.In the process of separate and enrich of vanadium from stone coal acid leaching, the resultindicates that it is feasible to use precipitation and separation to concentrate vanadium. Thespecific process can be described as follows, adding30g/L K₂SO₄, using Ca（OH）2to adjust pH tobe around2, and make most of metal ions like Al3+, Fe3+removed. H₂O₂was selected as theoxidant to oxidize V（Ⅳ） to V（Ⅴ）,99.7%of vanadium could be obtainedin precipitation afteradjusting the pH value of the solution to4by using Na2CO₃, and remaining95℃for2h understirring. And then roasting the precipitation including vanadium with60%NaOH at thetemperature of600℃, remaining2h with liquid-solid ratio of1:1, in the process,97.5%vanadium could be extracted from the precipitation.Results of the precipitation of vanadium and the preparation of vanadium products show that,ammonium metavanadate can be direactly precipitated by adding NH4Cl. In the31g/L ofvanadium alkaline leaching solution, the optimum technological conditions of precipitatingvanadium are the coefficient of ammonification K=4.0, remaining95℃for2h under stirring.After the process of precipitation, washing and being roasted, the purity rate of products can reach 98%and meets the vanadium pentoxide specification of National Standards metallurgical98-level（GB3283-87）.This process has the advantages of low consumption of chemicals, simplicity of operation,low costs and lighter environmental pollution, and it can realize efficient recycling of elementvanadium. Meanwhile, there are no poisonous and harmful gas produced during the entire process,the different kinds of produced waste water can be neutralized with each other, and parts ofpurified water can be reused, parts can be discharged after reaching emission standard. Thisprocess is environmental friendly and of good applicability.