Method for treating waste water generated in ionic rare earth production

Abstract

The invention discloses a method for treating waste water generated in ionic rare earth production. The method includes (1) feeding sodium carbonate into the waste water, keeping the pH (potential of hydrogen) value to range from 7.5 to 8.5, mixing the sodium carbonate with the waste water for 10 to 25 minutes, settling the mixture for 15 to 35 minutes, separating sediment and enabling calcium ion removal rate to reach 98% at least; (2) regulating the pH value of the mixture to range from 8.5 to 9.5 by supernate after sedimentation, simultaneously feeding magnesium chloride and sodium hydrogen phosphate into the mixture according to a ratio of n(Mg):n(N):N(P) of (1.5-2):(1-1.5):(1.2-2), mixing and stirring the mixture for 20 to 30 minutes, settling the mixture for 15 to 30 minutes, separating mud from water; and (3) repeating the step (2) once, regulating the pH value to range from 6 to 9 by the aid of hydrochloride acid after settling and water draining are performed in a secondary MAP (magnesium ammonium phosphate) method, then removing salt by a reverse osmosis membrane, and recycling drained water for production. The quantity of the fed sodium carbonate ranges from 105% to 120% of the molar concentration of calcium ions. Reveres osmosis concentrated liquor is used as an industrial salt raw material to be recycled after being dried. The method has the advantages of low cost, thorough and short reaction process, small size of reaction device, simple equipment and the like.

Description

technical field [0001] The invention relates to a method for comprehensively treating oxalic acid and ammonium bicarbonate to separate ion-type rare earth wastewater by using a combined process of chemical precipitation and reverse osmosis. Background technique [0002] The production process of rare earth is as follows: add water and hydrochloric acid to the dissolving tank for mixing rare earth raw materials, stir and dissolve, and obtain filtrate and filter residue after the solution is filtered. The filtrate is directly pumped into the extraction tank, and the light, medium and heavy rare earth elements are grouped and separated in the extraction system to obtain a single rare earth material liquid, and oxalic acid or ammonium bicarbonate is added to precipitate the single rare earth, and the precipitated rare earth salts are washed, After filtration and burning, a single rare earth oxide product is obtained. [0003] According to research, according to the above-mentio...

AI Technical Summary

Problems solved by technology

During the rare earth production process, a large amount of wastewater containing high chlorine, high nitrogen, high oxalic acid, high calcium and other ions will be produced, which is difficult to be treated biochemically or physically, and will easily lead to salinization of the soil and eutrophication of the water body, which must be treated

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