Double decomposition method for preparing potassium nitrate

Abstract

The invention provides a double decomposition method for preparing potassium nitrate from ammonium nitrate and potassium chloride, and relates to the technical field of inorganic chemical engineering. In the prior art, the mother liquid is circularly used, potassium chloride brings in impurities, and the impurities in mother liquid are accumulated and are not processed in circulation for a long period. The double decomposition method is characterized in that a distribution impurity-removing production line is arranged tightly near to production equipment, wherein the distribution impurity-removing production line is provided with a sodium and magnesium removing unit; 1% to 30% of the total circulation amount of mother liquid is introduced into the production line to carry out an impurity removing treatment, wherein the main components of the impurities are water-soluble sodium salt and magnesium salt, magnesium chloride is taken as a salting-out agent to remove sodium salt, ammonium bicarbonate is taken as a precipitating agent to remove magnesium salt, the solution temperature is 10 DEG C to 90 DEG C, and the processed mother liquid is returned to the mother liquid circulation system.

Description

Technical field [0001] The invention relates to the technical field of inorganic chemical industry, and relates to a method for preparing potassium nitrate by double decomposition. Background technique [0002] Potassium nitrate has a wide range of uses in industry and agriculture. In industry, it is used to make fireworks, black gunpowder, matches, medicines, catalysts, ceramic glaze medicines, and glass clarifiers. In recent years, with the development of regenerative solar energy utilization, potassium nitrate is used as a raw material for high-temperature molten salt. The volume keeps increasing. In terms of agriculture, it is a high-efficiency nitrogen-potassium compound fertilizer and a high-efficiency chlorine-free potassium fertilizer. Among the three major potassium fertilizers: potassium chloride, potassium sulfate, and potassium nitrate, potassium nitrate has high grade, fast fertilizer efficiency, and no residue, and is suitable for all crops. With the developm...

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Problems solved by technology

With the gradual increase of the accumulation of impurities in the mother liquor, the impurities in the product gradually increase, which affects the quality of the product, and at the same time leads to a gradual decrease in product yield and a gradual increase in product energy consumption

The weak point of above patented technology is, there is the accumulative problem of impurity in mother liquor in the long-term circulation, does not see as the potassium nitrate production plant circulation mother liquor impurity removal technology disclosed by the present invention

[0004] (2) "Mother liquor treatment in the production process of potassium nitrate - separation of nitric acid and hydrochloric acid by solvent extraction" (Du Fanglin, Gong Yuzhen. Shandong Chemical Industry, No. 1, 1997), which discloses the production method of potassium nitrate, using tributyl phosphate Ester is used as extractant, and kerosene is used as diluent, which can effectively extract nitric acid from mother liquor to achieve the purpose of complete separation of nitric acid and hydrochloric acid. Mother liquor impurity removal technology

In order to further optimize the utilization of the mother liquor, an experimental study was carried out in which the mother liquor first extracted the rare earth-containing phosphate rock, and then neutralized it step by step with magnesium-containing compounds and ammonium bicarbonate to prepare rare earth phosphates and slow-release ternary compound fertilizers with higher economic value. , the weak point is that there is no impurity removal technology for the circulating mother liquor of the potassium nitrate production plant disclosed in the present invention

[0006] (4) "New Process for Preparing Potassium Nitrate by Conversion of Sodium Nitrate" (Zhang Gang. Chemical Design, 2009, 19(5)), which discloses the production method of potassium nitrate, the process of producing potassium nitrate by double decomposition of sodium nitrate and potassium chloride In the paper, the accumulation and treatment of impurities in the mother liquor were noticed, and it was proposed that the mother liquor should be regularly treated to remove impurities to ensure the product quality and normal production operation. It was proposed that the main impurities in the mother liquor were sodium nitrite, sodium sulfate and magnesium chloride, and the solution was to add Ammonium nitrate removes sodium nitrite, adds barium chloride to remove sodium sulfate, adds potassium carbonate to remove magnesium chloride, and the disadvantage is that there is no technology for removing impurities in the circulating mother liquor of potassium nitrate production plant disclosed in the present invention

[0007] (5) Chinese Patent Publication No. CN1113886A (disclosure date on December 27, 1995), discloses the method for preparing potassium nitrate process mother liquor recycling, the circulating mother liquor containing sodium nitrate is reacted with potassium chloride to obtain solid sodium chloride and nitric acid Potassium mother liquor, cooling obtains potassium nitrate product, separates mother liquor and drops into sodium chloride, ammonium nitrate, obtains by-product ammonium chloride and the circulation mother liquor that contains sodium nitrate, and weak point is not seen as the potassium nitrate production plant circulation mother liquor disclosed by the present invention Impurity removal technology

[0008] (6) Chinese Patent Publication No. CN1371864A (disclosure date on October 2, 2002), discloses the method for preparing potassium nitrate process mother liquor recycling, mixing salt lake potassium resource ore with natural sodium saltpeter and potassium nitrate mother liquor, adjusting potassium, nitric acid The mass ratio of roots and water is used to make the mixed material undergo thermal dissolution conversion reaction to form a solid-liquid mixed slurry, which is separated to obtain a hot-soluble saturated clear liquid, and is cooled to room temperature to precipitate potassium nitrate. There is no technology for removing impurities in the circulating mother liquor of the potassium nitrate production unit disclosed in the present invention

[0009] (7) Light magnesium carbonate and medicinal magnesium carbonate (Second Edition of Inorganic Salt Industry Handbook, Volume 2, pp. 1054-1061), which discloses the preparation of light magnesium carbonate and medicinal magnesium salts (magnesium chloride, magnesium sulfate) and ammonium bicarbonate. With magnesium carbonate technology, relate to a kind of removal technology of magnesium salt, weak point is that there is no technology for removal of impurities in the circulating mother liquor of potassium nitrate production plant as disclosed in the present invention

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