Zero discharge and resource utilization method for vanadium-containing high-salinity wastewater

Abstract

The invention relates to a method for zero discharge and resource utilization of vanadium-containing high-salinity wastewater, and discloses a method for treating vanadium-containing high-salinity wastewater obtained by sodium-process vanadium extraction, which comprises the following steps: recovering and enriching vanadium ions, chromium ions and other ions through chemical reduction precipitation, and then returning to a sodium-process vanadium extraction process; sodium sulfate and sodium chloride in the salt are separated and recycled through the specific combination of two times of evaporative crystallization and one time of cooling crystallization, evaporation condensate water serves as reclaimed water to be recycled, the separated sodium sulfate can be sold in the form of a sold product, the separated sodium chloride can be returned to the sodium-method vanadium extraction process to be recycled, no impurity salt is discharged, and the method is environmentally friendly. Therefore, efficient green treatment and zero emission of the high-salinity wastewater are realized.

Description

technical field [0001] The invention relates to the field of water treatment, in particular to a water treatment process for vanadium-containing high-salt wastewater in the metallurgical industry. Background technique [0002] It is understood that the total volume of vanadium trade in the world is 150,000 tons / year, and vanadium elements such as steel slag and stone coal are mainly extracted through the sodium vanadium extraction process. In the sodium vanadium extraction process, the amount of sodium chloride used The leaching rate is the largest when it is close to 8 times the mass of vanadium in vanadium ore, and the demand for sodium chloride in the vanadium extraction industry by sodium method is huge. At present, the vanadium extraction route consumes a large amount of sodium chloride and produces waste water containing a large amount of sodium chloride, which not only wastes resources but also causes pollution. [0003] Since the wastewater produced in the sodium va...

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Problems solved by technology

At present, while the vanadium extraction route consumes a large amount of sodium chloride, it also produces wastewater containing a large amount of sodium chloride, which not only wastes resources but also causes pollution

[0003] Because the waste water produced in the process of extracting vanadium by sodium method contains not only toxic heavy metal ions such as vanadium and titanium, but also rich in various inorganic salts such as calcium, magnesium, sodium chloride and sodium sulfate, the concentration of salt is high, and the treatment is difficult. Direct discharge will cause huge pressure on the environment, so relevant wastewater treatment technologies are urgently needed to treat high-salt wastewater

[0004] At present, some technologies have been disclosed regarding the resource utilization of vanadium-containing high-salt wastewater, including, for example, the chemical precipitation method, which first reduces pentavalent vanadium to tetravalent vanadium and trivalent vanadium, and simultaneously reduces hexavalent chromium to trivalent chromium, and then Neutralization and precipitation to recover vanadium and chromium; ion exchange method, using ion exchange resin to absorb vanadium, chromium and other heavy metal ions in wastewater, and then desorb and regenerate the resin for reuse; and extraction method, electrolysis method, adsorption method and biological method Etc., also disclosed the technology that the salt in waste water is recycled while reclaiming heavy metal ions such as these chromium, vanadium, for example CN108911237 A, it is mainly by separating out chromium, sodium sulfate and carrying out vanadium-containing waste water Recycling reduces the treatment cost of vanadium-containing wastewater, but directly using cooling crystallization to desalinate wastewater can only remove a small part of sodium sulfate, and a large amount of sodium sulfate still exists in wastewater, so the resource utilization of sodium sulfate is not thorough

In addition, the obtained salt is sodium sulfate decahydrate, which requires further decrystallization water, which increases the cost and complexity of the salt extraction operation

[0005] In the prior art, most of the reports on the treatment of vanadium-containing high-salt wastewater are aimed at a certain local treatment, especially focusing on how to improve the recovery of heavy metals such as chromium and vanadium, but there is still a lack of recovery and reuse of salts. The system solution cannot effectively recycle the salt in it, and the technical cost is relatively high. In particular, the problem of miscellaneous salt discharge has not been solved

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