Method for clean production of vanadium pentoxide

Abstract

The invention discloses a method for the clean production of vanadium pentoxide, and belongs to the field of production of vanadium oxide. The method comprises the steps of raw material pretreatment, roasting, diluted acid leaching, vanadium liquid purification, vanadium precipitation, pyrolysis, recovery of Mn in residual vanadium precipitation liquid and the like. According to the method, the discharge of the residual vanadium precipitation liquid is avoided, and vanadium extraction tailings do not contain Na and K, and can be returned to a blast furnace or directly reduced to realize the comprehensive recycling of resources; the total recovery rate of vanadium is higher than that of a conventional sodium salt roasting-water leaching vanadium extraction process in the industry, the V2O5 content of a product is higher than 98 percent, the production cost is lower than that of a process for the sodium treatment vanadium extraction preparation of vanadium pentoxide, and meanwhile, the residual vanadium precipitation liquid can be completely recycled, and the vanadium extraction tailings can be secondarily and comprehensively utilized.

Description

technical field [0001] The invention belongs to the field of vanadium oxide production, in particular to a method for clean production of vanadium pentoxide. Background technique [0002] For vanadium-titanium magnetite, vanadium slag, steel slag and other raw materials for extracting vanadium, most of the industry currently uses the traditional sodium roasting-water immersion process to produce vanadium pentoxide, and the sodium salt additives are NaCl, Na 2 SO 4 、Na 2 CO 3 and NaNO 3 The combination of one or several sodium salts in the medium is evenly mixed with the vanadium-containing material and then roasted at high temperature. The roasting temperature is 700-800°C. The amount of sodium salt added is 10%-20% by weight. The conversion of low-priced vanadium in the vanadium raw material It is pentavalent vanadium, which combines with sodium in the additive to form sodium vanadate which is soluble in water. The roasted clinker is leached with water, and after solid...

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Problems solved by technology

(2) During the sodium roasting process, harmful gases HCl and Cl will be decomposed 2 , SO 2 and SO 3 etc., pollute the environment and corrode equipment; the melting point of sodium salt is low, and it is easy to form rings and stick to the furnace during the roasting process, which affects the conversion rate of vanadium; the addition of sodium salt is large, and the production cost is high; (3) the tailings of sodium vanadium extraction contain alkali High (about 5%), it has been difficult to comprehensively utilize. Tailing slag ingredients in ironmaking will cause nodules in the blast furnace, deteriorate the air permeability of the blast furnace material column, erode the furnace lining, and affect the operation of the blast furnace

(5) Roasting with sodium salt - it is difficult to recycle the mother liquor of vanadium precipitation after ammonium salt precipitation

Due to the high sodium content in the vanadium precipitation mother liquor, and the sodium will continue to enrich during the circulation process, it is necessary to add more ammonium sulfate in the vanadium precipitation process, and the accumulation of a large amount of sulfate will increase the viscosity of the vanadium-containing solution. During the process, the phenomenon of "sinking" occurs. At present, the vanadium precipitation wastewater of vanadium production enterprises adopts the method of terminal treatment, and it is discharged directly after the removal of vanadium, chromium and neutralization treatment, but this will salinize the surrounding land and affect the growth of plants. , destroy the ecological environment

(6) The vanadium recovery rate of the traditional sodium roasting vanadium extraction technology is low, and the single-pass vanadium extraction rate is about 75%. The vanadium in the tailings is mostly extracted by secondary roasting to reduce its content, and the secondary vanadium extraction rate is lower than 50%. Only 80% after multiple firings

New vanadium extraction technologies such as sub-molten salt vanadium extraction technology and direct acid leaching technology both use ion exchange and solvent extraction to purify vanadium-containing solutions, but ion exchange is only suitable for small-scale use, and cannot be used for vanadate anions and Si, Al, and P. Effective separation; solvent extraction consumes a large amount of high-concentration acid solution in the pre-extraction sulfonation and stripping sections, and the stripping solution containing a small amount of organic phase cannot be recycled and forms a new source of pollution

In addition, ion exchange and solvent extraction purify vanadium-containing solution compared with chemical precipitation to remove impurities, the process is complicated and the cost is high

[0008] So far, there is no such thing that can efficiently extract vanadium from vanadium-containing raw materials, and solve the problem of removing impurities Ca, Mg, Al, and Si in the acidic vanadium leaching solution, and obtain V with a grade > 98%. 2 o 5 At the same time, it can completely solve the relevant research reports on the recycling of vanadium precipitation wastewater and the comprehensive utilization of vanadium extraction tailings

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