Method for separating and reclaiming vanadium and chromium from solution containing vanadium and chromium

Abstract

This invention relates to an entirely new technology of completely recovering chromium and vanadium from vanadium-chromium miscible liquid. The main procedures include: first a primary-secondary compound amine extracting agent contacts the vanadium-chromium miscible liquid by means of countercurrent contact and extract, so as to extract most of vanadium and a small amount of chromium into a organic phase while most of chromium stays into a aqueous phase; and a reduction reaction is conducted with pH of acid adjustable faffinate (aqueous phase) and a certain amount of a reducing agent; the sodium hydroxide is used for adjusting pH value of the solution and filter, and finally the product is hydrous chromium oxide; at that time, the lye is used as a stripping agent; the vanadium is stripped from the vanadium-rich organic phase into water in the manner of countercurrent contact; and the vanadium is separated from the solution witthe method of ammonium precipitation and in the form of ammonium metavanadate; and finally the supernatant clear solution of the one is processed with deposited vanadium with a high-efficient distillation technology, and the strong aqua ammonia is left in the tower top and deamidization solution is left in the tower bottom until the extraction process is reached. The invention uses the primary-secondary compound amine as the extracting agent, extracts and separates vanadium and chromium selectively at a low temperature. The invention not only has a simple process flow, but also is low-cost, quite applicable in large-scale industrial production. In addition, the invention also provides high-purity ammonium metavanadate and 16 percentage strong aqua ammonia, and makes sure the vanadium and chromium can be completely recovered through re-use of the solution.

Description

technical field [0001] The invention belongs to the field of hydrometallurgy or wastewater treatment, and relates to a method for separating vanadium and chromium from a vanadium-chromium solution, in particular to a method for separating vanadium and chromium from a vanadium-chromium-containing solution by using an extraction-chemical precipitation-medium circulation combined process Process for recovery of vanadium and chromium. Background technique [0002] Both vanadium and chromium are important strategic resources, and both pentavalent vanadium and hexavalent chromium are very toxic, seriously threatening human health and safety. Due to their similar properties, vanadium and chromium usually exist in minerals in a symbiotic manner, resulting in the simultaneous entry of pentavalent vanadium and hexavalent chromium into the aqueous solution (including wastewater) during mineral processing, which is difficult to separate from each other, which not only causes waste of re...

AI Technical Summary

Problems solved by technology

Due to their similar properties, vanadium and chromium usually exist in minerals in a symbiotic manner, resulting in the simultaneous entry of pentavalent vanadium and hexavalent chromium into the aqueous solution (including wastewater) during mineral processing, which is difficult to separate from each other, which not only causes waste of resources, but also seriously polluted environment

[0003] So far, people have developed a variety of technologies for treating wastewater containing vanadium and chromium. Among them, the ferrous sulfate reduction method or iron filings reduction method is relatively simple and mature, but the biggest disadvantage is that It is difficult to recover vanadium and chromium resources in water, and it is easy to produce secondary pollution

In addition, in order to improve the oxidizing properties of vanadium and chromium, it is usually necessary to add acid to adjust the pH value of the water to below 4 before chemical reduction, which consumes a lot of acid resources

Sulfur dioxide and sodium sulfite are used to treat wastewater. Although vanadium and chromium can be recovered, since both pentavalent vanadium and hexavalent chromium have strong oxidizing properties, it is easy to cause simultaneous reduction of pentavalent vanadium and hexavalent chromium, which affects the yield.

Chinese patent CN1073414A adopts FeCl 3 Precipitate vanadium, and then use chemical reduction to recover chromium. This technology is difficult to obtain high-purity vanadium pentoxide and chromium oxide, and the process route is relatively complicated, and the processing cost is also high.

Chinese patent CN1065494A uses a large pore size weakly basic anion exchange resin to selectively adsorb vanadium, and the effect is better, but due to the limited capacity of the resin, it is difficult to treat high-concentration wastewater

Chinese patent CN86106414 uses iron anode electrolysis to treat vanadium-containing wastewater, respectively reducing pentavalent vanadium and hexavalent chromium in water to solids of trivalent vanadium and trivalent chromium, and the removal of vanadium and chromium in water is more obvious, but due to the Separation still requires high-temperature calcination, so the equipment investment is large, the treatment cost is high, and it is still difficult to separate vanadium and chromium again

Chinese patent CN1035998A adopts vanadium slag particle iron rolling method to treat vanadium-chromium-containing wastewater, and waste is treated with waste, but it is difficult to realize the recovery of vanadium resources

This technology is relatively simple, and can obtain higher purity vanadium and chromium products, but due to the limited capacity of the extractant, it is difficult to obtain high-concentration vanadium liquid

In addition, the extraction agent reported in the patent cannot yet achieve complete separation of vanadium and chromium, and the patent does not involve the treatment of the supernatant after vanadium precipitation, so the full recovery of vanadium and chromium resources cannot be realized

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