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CN-121974376-A - Mirabilite recycling method based on micro-nano bubble reinforced mass transfer

CN121974376ACN 121974376 ACN121974376 ACN 121974376ACN-121974376-A

Abstract

The invention belongs to the technical field of mirabilite recycling, and particularly relates to a mirabilite recycling method based on micro-nano bubble reinforced mass transfer. The method comprises the steps of (1) dissolving mirabilite solid waste water or concentrating mirabilite waste water to enable sodium sulfate concentration to be close to a saturated state, obtaining mirabilite solution, (2) firstly introducing ammonia gas in micro-nano bubble forms into the mirabilite solution in the step (1) to form a sodium sulfate solution system rich in dissolved ammonia, then continuously introducing carbon dioxide in micro-nano bubble forms for crystallization precipitation reaction, (3) carrying out solid-liquid separation on the reaction materials in the step (2), washing and drying the solid phase to obtain sodium bicarbonate products, adding sulfuric acid into the liquid phase to react to convert the dissolved sodium bicarbonate into sodium sulfate, concentrating-crystallizing the solution to obtain ammonium sulfate crystal products, and recycling the residual mother liquor in the step (1). The method can simultaneously obtain the sodium bicarbonate product and the ammonium sulfate product with high purity through simple process.

Inventors

  • ZHOU MINGPU

Assignees

  • 厦门正元环境科技有限公司

Dates

Publication Date
20260505
Application Date
20260309

Claims (10)

  1. 1. A mirabilite recycling method based on micro-nano bubble reinforced mass transfer is characterized by comprising the following steps: (1) Dissolving mirabilite solid waste water or concentrating the mirabilite waste water to ensure that the concentration of sodium sulfate is close to a saturated state to obtain a mirabilite solution; (2) Firstly, introducing ammonia gas in the form of micro-nano bubbles into the mirabilite solution in the step (1) to form a sodium sulfate solution system rich in dissolved ammonia, and then continuously introducing carbon dioxide in the form of micro-nano bubbles to carry out crystallization precipitation reaction; (3) And (3) carrying out solid-liquid separation on the reaction material in the step (2), washing and drying a solid phase to obtain a sodium bicarbonate product, adding sulfuric acid into a liquid phase to react to convert dissolved sodium bicarbonate into sodium sulfate, concentrating and crystallizing the solution to obtain an ammonium sulfate crystal product, and recycling the residual mother liquor in the step (1).
  2. 2. The method for recycling mirabilite based on micro-nano bubble reinforced mass transfer of claim 1, wherein in the step (1), the near saturation state is that the concentration of sodium sulfate is controlled to be 70% -95% of the saturation solubility at the current operating temperature.
  3. 3. The mirabilite recycling method based on micro-nano bubble reinforced mass transfer according to claim 1 is characterized in that the operation temperature of the step (1) and the step (2) is controlled to be 30-40 ℃.
  4. 4. The method for recycling mirabilite based on micro-nano bubble intensified mass transfer according to claim 1, wherein the average bubble diameter of the micro-nano bubble form in the step (2) is smaller than 1 μm.
  5. 5. The mirabilite recycling method based on micro-nano bubble reinforced mass transfer according to claim 1, wherein the molar ratio of the ammonia gas introduced in the step (2) to sodium sulfate in the mirabilite solution is 2-2.6:1, and the ammonia gas which is not absorbed after the ammonia gas is introduced is recovered for recycling after gas-liquid separation.
  6. 6. The mirabilite recycling method based on micro-nano bubble reinforced mass transfer according to claim 1, wherein the molar ratio of the carbon dioxide introduced in the step (2) to sodium sulfate in the mirabilite solution is 2-2.6:1, the carbon dioxide introduced time is 20-60 min, and unreacted carbon dioxide after the carbon dioxide introduced is recovered for recycling after gas-liquid separation.
  7. 7. The mirabilite recycling method based on micro-nano bubble reinforced mass transfer according to claim 1, wherein in the step (2), after carbon dioxide is introduced, the system is concentrated to 50-60% of the original water content, and the temperature is reduced to 5-15 ℃ and kept stand for 20-60min to promote sodium bicarbonate crystal growth.
  8. 8. The method for recycling mirabilite based on micro-nano bubble enhanced mass transfer according to claim 1, wherein the solid-liquid separation in the step (3) is realized by filtration, centrifugation or sedimentation.
  9. 9. The mirabilite recycling method based on micro-nano bubble reinforced mass transfer according to claim 1, wherein the molar ratio of the sulfuric acid addition amount to the dissolved sodium bicarbonate in the step (3) is 0.8-1.2:1.
  10. 10. The mirabilite recycling method based on micro-nano bubble reinforced mass transfer according to claim 1 is characterized in that concentration in the step (3) is concentration to 1/3-1/5 of the original water content, and the crystallization temperature is 30-40 ℃.

Description

Mirabilite recycling method based on micro-nano bubble reinforced mass transfer Technical Field The invention belongs to the technical field of mirabilite recycling, and particularly relates to a mirabilite recycling method based on micro-nano bubble reinforced mass transfer. Background The mirabilite solid waste or wastewater (the main component is sodium sulfate) is widely sourced from salt chemical industry, phosphating industry and related inorganic salt production processes, has large yield and low added value, is mainly piled up as a low-value byproduct or simply treated for a long time, not only causes resource waste, but also can cause environmental problems. In the prior art, a route for preparing 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 taking 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 prior art generally adopts ammonium bicarbonate and mirabilite to carry out double decomposition reaction, or firstly CO 2 gas is introduced into ammonia water to prepare ammonium bicarbonate aqueous solution, then the ammonium bicarbonate aqueous solution and mirabilite are subjected to double decomposition reaction, and sodium bicarbonate is utilized to have the solubility in water which is obviously lower than that of ammonium sulfate/sodium sulfate (double salt) so as to crystallize and separate sodium bicarbonate components. The main reaction process involved is 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. however, the following disadvantages still exist in the practical application process: (1) The preparation of ammonium bicarbonate in advance is needed, the process flow is increased, or the unstable ammonium bicarbonate raw material is adopted, so that the requirement on the storage condition is high. (2) The reaction efficiency is low, the Na 2SO4 conversion rate is low, the content of sodium sulfate double salt in the mother solution after separating sodium bicarbonate components is high, and the subsequent separation difficulty of the (NH 4)2SO4 product is increased. (3) The residual dissolved NaHCO 3 in the mother liquor after separating the NaHCO 3 components by crystallization precipitation is difficult to separate from (NH 4)2SO4) and is difficult to separate by crystallization treatment to obtain a high purity (NH 4)2SO4 product, which requires a complicated separation step. (4) The crystallization and precipitation process of NaHCO 3 is unstable, the concentration of HCO 3-、Na2SO4 in the early stage is high, and the crystallization speed leads to inclusion of impurity ion components easily, so that the quality of sodium bicarbonate products is affected. Therefore, a new method for recycling mirabilite, which can remarkably improve the reaction efficiency and also has the product quality and the economy, is needed. Disclosure of Invention Aiming at the defects and shortcomings of the prior art, the invention aims to provide a mirabilite recycling method based on micro-nano bubble reinforced mass transfer. The invention aims at realizing the following technical scheme: A mirabilite recycling method based on micro-nano bubble intensified mass transfer comprises the following steps: (1) Dissolving mirabilite solid waste water or concentrating the mirabilite waste water to ensure that the concentration of sodium sulfate is close to a saturated state to obtain a mirabilite solution; (2) Firstly, introducing ammonia gas in the form of micro-nano bubbles into the mirabilite solution in the step (1) to form a sodium sulfate solution system rich in dissolved ammonia, and then continuously introducing carbon dioxide in the form of micro-na