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CN-121974377-A - Iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite

CN121974377ACN 121974377 ACN121974377 ACN 121974377ACN-121974377-A

Abstract

The invention belongs to the technical field of mirabilite recycling, and particularly relates to an iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by mirabilite recycling. The method comprises the steps of introducing carbon dioxide gas into ammonia water for reaction to obtain an ammonium bicarbonate aqueous solution, adding mirabilite solid or solution into the ammonium bicarbonate aqueous solution to prepare a mixed solution, firstly reacting for 10-30 min at a low temperature of 0-30 ℃, then heating to 85-95 ℃ for heat preservation reaction for 30-60 min, filtering while the reaction is finished to obtain a sodium carbonate product and an ammonium sulfate enriched mother solution, cooling the ammonium sulfate enriched mother solution to 35-45 ℃ for crystallization, enabling the solid phase to be the ammonium sulfate product, and iteratively recycling the rest circulating mother solution for preparing the mixed solution. The method can directly obtain high-purity sodium carbonate and ammonium sulfate by a crystallization separation method.

Inventors

  • ZHOU MINGPU

Assignees

  • 厦门正元环境科技有限公司

Dates

Publication Date
20260505
Application Date
20260309

Claims (9)

  1. 1. An iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite is characterized by comprising the following steps: (1) Introducing carbon dioxide gas into ammonia water to react to obtain ammonium bicarbonate aqueous solution; (2) Adding mirabilite solid or solution into ammonium bicarbonate aqueous solution to prepare a mixed solution, reacting for 10-30 min at a low temperature of 0-30 ℃, heating to 85-95 ℃ to perform heat preservation reaction for 30-60 min, and filtering while the reaction is hot to obtain sodium carbonate products and ammonium sulfate enriched mother solution; (3) And (3) cooling the ammonium sulfate enrichment mother liquor in the step (2) to 35-45 ℃ for crystallization, wherein the solid phase is an ammonium sulfate product, and the rest circulating mother liquor is recycled for preparing the mixed solution in the step (2).
  2. 2. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite, which is characterized in that in the step (1), carbon dioxide gas is introduced into ammonia water for reaction, namely, carbon dioxide gas is introduced into a micro-nano bubble generator for reaction under the stirring condition and at the temperature of 5-35 ℃ until the pH value is kept at 8.5-9.5.
  3. 3. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite according to claim 1, wherein in the preparation of the mixed solution in the step (2), the concentration of the ammonium sulfate is controlled to be 85% -100% of the solubility at the temperature of 85-95 ℃.
  4. 4. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite, which is disclosed in claim 1, is characterized in that the heating rate in the step (2) is controlled to be 1-2 ℃ per minute, and the heating process is kept to be stirred at a rate of 200-400 r per minute.
  5. 5. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite according to claim 1, wherein the heat preservation reaction in the step (2) adopts a closed system or adopts a condensation recovery device.
  6. 6. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite according to claim 1, wherein the hot filtering in the step (2) is vacuum filtration or centrifugal filtration.
  7. 7. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite, which is disclosed in claim 1, is characterized in that the cooling rate in the step (3) is controlled to be 1-2 ℃ per minute, and the cooling process is kept to be slowly stirred at 100-200 r/min.
  8. 8. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite, which is disclosed in claim 1, is characterized in that the crystallization time in the step (3) is 30-60 min, and the crystallization process is kept at 100-200 r/min and is slowly stirred.
  9. 9. The iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite according to claim 1, wherein the solid phase after crystallization in the step (3) is separated by vacuum filtration or centrifugal filtration, and the ammonium sulfate product is obtained after drying.

Description

Iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite Technical Field The invention belongs to the technical field of mirabilite recycling, and particularly relates to an iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by mirabilite recycling. Background Natrii sulfas is used as a large amount of byproducts generated in the chemical production and salt lake development processes, the main component is sodium sulfate, and the sodium sulfate is directly piled up or utilized in a low value, so that not only land resources are occupied, but also salinization and leachate environmental risks can be possibly caused. The existing mirabilite recycling way is mainly focused on preparing sodium sulfate products or simply converting the sodium sulfate products into ammonium sulfate, but the problems of low added value of the products, low purity of the ammonium sulfate and large consumption of raw materials and energy generally exist. Although ammonia and carbon dioxide in the traditional Soxhlet method system can be recycled, high-value conversion of sulfate radical cannot be realized. How to realize the iterative recycling of mother liquor while improving the purity of the conversion product is a key technical problem of high-valued utilization of mirabilite. In the prior art, a route for preparing sodium carbonate/sodium bicarbonate and ammonium sulfate by reacting sodium sulfate with an ammonium-containing system has been proposed, for example, the invention patent with publication number CN 109437248B discloses a method for jointly producing sodium carbonate and ammonium sulfate by using mirabilite and ammonium bicarbonate as raw materials, wherein ammonium bicarbonate, sodium sulfate and water are simultaneously added into a premixing tank with a stirrer, and the materials are initially reacted in the premixing tank to generate sodium bicarbonate crystals. The patent publication No. CN 114436297B discloses a method for preparing sodium carbonate from mirabilite, which utilizes the double decomposition reaction of ammonium bicarbonate and sodium sulfate, and the obtained precipitate is sodium bicarbonate. The invention patent with publication number CN 119430231A discloses a method for preparing sodium bicarbonate and co-producing ammonium sulfate by using low-temperature mirabilite, wherein ammonium bicarbonate solid is added into low-temperature mirabilite slurry, the reaction is carried out, the sodium bicarbonate is separated out by crystallization, and wet sodium bicarbonate and sodium bicarbonate mother liquor are obtained by solid-liquid separation. The main reaction processes involved in the prior art are as follows: (1) Ammonia and carbon dioxide react in the liquid phase to produce ammonium bicarbonate: NH3 + CO2 + H2O → NH4HCO3; (2) The ammonium bicarbonate and sodium sulfate undergo double decomposition reaction: Na2SO4 + 2 NH4HCO3 → 2 NaHCO3↓ + (NH4)2SO4; (3) Sodium bicarbonate thermal decomposition reaction: 2NaHCO3→Na2CO3+CO2↑+H2O。 However, the prior art generally comprises the steps of crystallizing and separating sodium bicarbonate solid under the condition of low temperature, and calcining at high temperature to obtain sodium carbonate product. On one hand, the process flow and the energy consumption are increased, and on the other hand, the residual sodium bicarbonate in the mother solution can be co-separated out in the subsequent concentration, cooling and crystallization processes of the ammonium sulfate product, so that the purity of the ammonium sulfate product is reduced, and a complex separation and purification process is needed. Disclosure of Invention Aiming at the defects and shortcomings of the prior art, the invention aims to provide an iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite. The invention aims at realizing the following technical scheme: An iterative production method for preparing high-purity sodium carbonate and ammonium sulfate by recycling mirabilite comprises the following steps: (1) Introducing carbon dioxide gas into ammonia water to react to obtain ammonium bicarbonate aqueous solution; (2) Adding mirabilite solid or solution into ammonium bicarbonate aqueous solution to prepare a mixed solution, reacting for 10-30 min at a low temperature of 0-30 ℃, heating to 85-95 ℃ to perform heat preservation reaction for 30-60 min, and filtering while the reaction is hot to obtain sodium carbonate products and ammonium sulfate enriched mother solution; (3) And (3) cooling the ammonium sulfate enrichment mother liquor in the step (2) to 35-45 ℃ for crystallization, wherein the solid phase is an ammonium sulfate product, and the rest circulating mother liquor is recycled for preparing the mixed solution in the step (2). Further, in the step (1), the carbon dioxide gas is introduced into ammonia water for r