Method for preparing high-purity vanadium pentoxide from vanadium-chromium solution without ammonium

Abstract

The invention discloses an ammonium-free method for preparing high-purity vanadium pentoxide from a vanadium-chromium solution, which comprises the following steps: adding calcium sulfate into the vanadium-chromium solution, adjusting the pH value, heating and stirring to obtain calcium vanadate precipitate and vanadium-free chromium-containing filtrate; washing the calcium vanadate precipitate, and mixing the washed calcium vanadate precipitate with water and a sulfuric acid solution to obtain vanadium-containing leachate and calcium sulfate precipitate; adding a sulfuric acid solution into the vanadium-containing leachate, heating and stirring to obtain hydrated vanadium oxide; mixing the hydrated vanadium oxide with water and an oxalic acid solution, heating and stirring to obtain a vanadyl oxalate solution and a calcium oxalate precipitate; adding an oxalic acid solution into the vanadyl oxalate solution to adjust the pH value, heating and stirring to obtain vanadium dioxide; calcining the vanadium dioxide to obtain vanadium pentoxide; stirring the calcium oxalate precipitate with water and a sulfuric acid solution to obtain an oxalic acid solution and a calcium sulfate precipitate; according to the method, ammonium salt is not used, ammonium-containing wastewater is not generated, waste residues are not discharged, and the purity of the prepared vanadium pentoxide is more than 99.5%; the calcium sulfate precipitate generated in the preparation process can be recycled.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and chemical industry, and specifically relates to a method for preparing high-purity vanadium pentoxide from a vanadium-chromium solution without ammonium. Background technique [0002] Both vanadium and chromium are important strategic resources with wide application fields and application prospects. Vanadium and chromium are both transition elements of the fourth period, and their chemical properties are similar. They often exist in minerals in the form of symbiosis in nature. Chromium is difficult to separate. Vanadium and chromium in vanadium titanomagnetite are extracted into vanadium slag by pyrotechnic method, and exist in vanadium slag in the form of spinel. At present, the domestic vanadium slag sodium roasting and calcification roasting processes are mainly aimed at the extraction and recovery of vanadium. The entire vanadium extraction process uses ammonium salt, which produces a l...

AI Technical Summary

Problems solved by technology

[0003] Thus, the Chinese patent CN109750169A uses a reducing agent to reduce vanadium and chromium to tetravalent vanadium and trivalent chromium respectively, adds a complexing agent to complex the tetravalent vanadium, adds alkali to precipitate the trivalent chromium, separates the trivalent chromium and then separates the tetravalent chromium. The valence vanadium is oxidized to pentavalent vanadium, and the vanadium is extracted by the traditional ammonium method. Although the present invention realizes the separation of vanadium and chromium, the vanadium is first reduced and complexed, and then the ammonium salt is oxidized to precipitate the vanadium. The process is complicated, and the complexing agent makes the whole production system COD exceeds standard, and ammonium salt is still used

In order not to use ammonium salts, Chinese patent CN111592042A uses hydrolysis to precipitate vanadium to obtain hydrated vanadium oxide, and then uses organic acid to desodiumize and purify the hydrated vanadium oxide. The direct hydrolysis method of this invention is a traditional method that has long been eliminated and is not suitable for vanadium-chromium solution. , and organic acids will also cause COD that is difficult to handle in the entire production system