Process for extracting vanadium and chromium from chromic slag by using waste acid of titanium powder plant

Abstract

The invention discloses a method for separating and extracting vanadium and chromium. The method comprises the following steps of: (1) producing chromium fine sand (Cr2O3) of which the content is over 80 percent and ferric vandate of which the content is over 20 percent from two waste materials by taking waste acid of a titanium powder plant as a leaching agent and vanadium-chromium slag (containing 2.5 to 4.5 percent of vanadium and 14 to 25 percent of chromium) as a raw material; (2) putting the vanadium-chromium slag into the waste acid to allow the chromium and the vanadium in the slag to form chromium sulfate and vanadyl sulfate which can be dissolved in water very easily, wherein the leaching time is about 6 hours; (3) adding a certain amount of steel making steel slag during leaching to fulfill the aim of generating a great deal of calcium sulfate when a great deal of calcium oxide meets the acid during filtration, and wrapping, adsorbing or and stopping 'silica gel' formed by silicon dioxide in the chromium slag by the calcium sulfate which is used as a filter medium to ensure that the filtration is performed smoothly; (4) adjusting the pH value of the filtrate to be 2.5 by using sodium hydroxide, and then adding an oxidant and oxydol to ensure that the chromium in the solution is oxidized to be hexavalent, the iron is oxidized to be trivalent, and the vanadium is oxidized to be pentavalent; (5) heating the leaching solution to the temperature of between 70 and 90 DEG C to ensure that the vanadium and the iron is combined together to generate water-fast 'ferric vandate', wherein the time for thermal precipitation is about one hour, and the vanadium residual in the solution is not more than 0.4 g / L; (6) adding sodium hydroxide into the solution of which the ferric vandate is filtered out, and fully stirring the mixture until the pH value of the solution is between 5.5 and 5.9 to ensure that the chromium in the solution is completely converted into chromium.

Description

Technical field: [0001] The invention relates to separating and extracting dichromium trioxide and ferric vanadate from vanadium-chromium-containing slag by using waste acid. technical background: [0002] At present, in the process of extracting vanadium from sodium roasted high vanadium slag, chromium combines with sodium ions in the form of hexavalent chromium to generate water-soluble sodium chromate (NaCrO 2 ), and then leached out by water, the hexavalent chromium in the waste liquid after vanadium precipitation has a strong carcinogenicity, which will cause serious water pollution problems to the surrounding environment of people's life, especially to the water system of the river basin, especially to the living environment. Drinking water poses a serious hazard. Therefore, the waste liquid hexavalent chromium must be discharged before it can be discharged. Because the waste acid also contains less vanadium, and sometimes due to the incomplete precipitation of vanad...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a kind of simple production technology, utilize the waste acid of titanium dioxide plant, be used for leaching chromium slag, and utilize the divalent iron in the waste acid to separate vanadium from solution, successfully solve the problem of vanadium, The technical problem of chromium is not easy to separate, and reduce the production cost, in order to achieve the purpose of "using waste to treat waste and recycling", which has great guiding significance for environmental protection and the development of circular economy

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