Method for removing heavy metal in rare earth extraction waste water

Abstract

The invention provides a method for removing heavy metal in rare earth extraction waste water, comprising the following steps: (1) adding a precipitator to the rare earth extraction waste water for pretreatment, then performing filter pressing to remove residues, and performing subsequent treatment on waste liquor; (2) adding a coagulant aid to the waste liquor treated in step (1), then adding thewaste liquor together with the coagulant aid into a reaction chamber of an electric flocculation reactor, starting the electric flocculation reactor for flocculation treatment, then adding an adsorbent at the water outlet of the electric flocculation reactor, discharging mixed liquor containing floccule and hydrogen produced in the flocculation treatment process from the water outlet, and then performing solid-liquid separation, so as to obtain a solution which can be directly discharged. By adopting the method for removing heavy metal in the rare earth extraction waste water, the heavy metalcontent in the treated solution is far lower than that of the national 'Rare Earth Industrial Pollutant Discharge Standard' GB26451-2011 by one to two orders of magnitude, the treatment effect is steady, and the treated solution can be directly discharged.

Description

technical field [0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method for removing heavy metals in rare earth extraction wastewater. Background technique [0002] Rare earths are widely used in military construction and modern electronics industries, and are a very important strategic resource. Since the reform and opening up, my country's rare earth industry has developed rapidly and made some achievements, but the large-scale mining of rare earth is also accompanied by serious environmental pollution. [0003] The industrial production of rare earth enterprises has widely adopted the organic phase extraction technology under acidic conditions, and the extraction agent is mainly phosphorus extraction agent. The extraction waste produced in the production process of rare earth smelting and separation has the characteristics of high salt content and oil content, mainly containing organic phases such as kerosene, P5...

AI Technical Summary

Problems solved by technology

The extraction waste produced in the production process of rare earth smelting and separation has the characteristics of high salt content and oil content, mainly containing organic phases such as kerosene, P507, and P204, as well as pollution factors such as strong acidity, high COD concentration, total phosphorus, and ammonia nitrogen; at the same time, due to rare earth The concentrate contains a large amount of heavy metals and radioactive elements, such as Cr, Cd, Pb, Zn, As, Th, U, etc. These elements will also enter the rare earth waste during the smelting process, making the heavy metal elements in the wastewater exceed the standard

Because the rare earth extraction waste not only contains a variety of heavy metal elements, but also contains a large amount of organic matter, phosphorus compounds, oil and other substances, the composition is very complex, and it is difficult to process and recover heavy metals.

[0004] In recent years, most of the rare earth production enterprises in China generally degrease and release the extraction waste to obtain the rare earth extraction wastewater, and then use lime to neutralize the precipitation and add sodium sulfide or recapture agent to remove heavy metals in the rare earth wastewater. However, the sodium sulfide or recapture agent used in this method is expensive, the operating cost is high, and there is instability when dealing with some heavy metals

In the face of increasingly severe environmental problems, the country has paid more and more attention to environmental protection. Sodium sulfide or recapture methods have been difficult to meet the national discharge standards. Therefore, it is urgent to research and develop a method that can effectively and stably remove heavy metals in rare earth extraction wastewater.

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