Method for co-producing sodium hexafluoroaluminate and biurea

Abstract

The invention discloses a method for co-producing sodium hexafluoroaluminate and biurea. The method comprises the following steps: (1) adding ammonium hexafluoaluminate into a sodium carbonate-removed refined hydrazine hydrate solution wherein sodium chloride in the refined hydrazine hydrate solution performs double decomposition reaction with the ammonium hexafluoaluminate, thus generating the sodium hexafluoroaluminate and ammonium chloride, and separating the sodium fluoroaluminate, thus obtaining a mother solution 1; (2) adding urea and hydrochloric acid into the mother solution 1 where hydrazine hydrate and urea in the mother solution 1 performs condensation reaction with the hydrochloric acid, thus generating the biurea and ammonium chloride, and separating the biurea, thus obtaining a mother liquid 2. According to the method, the sodium hexafluoroaluminate, the biurea and the ammonium chloride which are high in yield and high in purity can be respectively produced; the yield of the sodium hexafluoroaluminate is up to 99.3 percent or above, and the contents of fluorine and aluminum in the sodium hexafluoroaluminate can meet the requirement of the national standard; the yield of the biurea is up to 97 percent or above, and the purity is 98 percent or above; the yield of the ammonium chloride is 98 percent or above, and the purity can meet the industrial standard.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a method for co-producing sodium hexafluoroaluminate and biurea. Background technique [0002] Biurea is a chemical substance with the molecular formula C 2 h 6 N 4 o 2 . Chinese alias: N, N'-dicarbamohydrazide, molecular weight: 118.09524, mainly used in the production of ADC foaming agent. The conventional method for producing biurea is to first produce a crude solution of hydrazine hydrate by the urea-sodium hypochlorite method, which contains hydrazine hydrate, sodium carbonate, urea, sodium chloride and water. Among them, the content of hydrazine hydrate is 50-55g / L, sodium carbonate is 110-150g / L, sodium chloride is 130-150g / L, and then the crude solution of hydrazine hydrate is frozen and crystallized to separate sodium carbonate decahydrate, and then hydrochloric acid or sulfuric acid is added After neutralization to pH 3~5, add urea and heat to 102~120°C ...

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Problems solved by technology

Among them, the content of hydrazine hydrate is 50-55g / L, sodium carbonate is 110-150g / L, sodium chloride is 130-150g / L, and then the crude solution of hydrazine hydrate is frozen and crystallized to separate sodium carbonate decahydrate, and then hydrochloric acid or sulfuric acid is added After neutralization to pH 3~5, add urea and heat to 102~120°C for condensation reaction to generate biurea and ammonium chloride or ammonium sulfate, and biurea is obtained after separation. The centrifuged mother liquor contains sodium chloride and sulfuric acid Ammonium or ammonium chloride, urea, etc. are difficult to separate or treat and are discharged directly. The sodium chloride, ammonium sulfate or ammonium chloride in them are not recycled and are directly discharged, causing great pollution to the environment.

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