Novel method for preparing sodium bicarbonate and co-producing ammonium sulfate from sodium sulfate

Abstract

The invention provides a novel method for preparing sodium bicarbonate and co-producing ammonium sulfate from sodium sulfate. The method comprises the following steps of: (1) reacting a sodium sulfate solution (salting-out mother liquor obtained in the subsequent process) with ammonium bicarbonate to prepare sodium bicarbonate solid and sodium bicarbonate mother liquor; (2) adding sodium sulfate (comprising externally added sodium sulfate and sodium sulfate obtained in the step (3)) into the sodium bicarbonate mother liquor, reacting under certain conditions, and performing liquid-solid separation to respectively obtain double salt and salting-out mother liquor; (3) washing the double salt with ammonium sulfate mother liquor and evaporation condensate water in the subsequent process to obtain an ammonium sulfate solution and sodium sulfate; and (4) evaporating the ammonium sulfate solution to obtain an ammonium sulfate product, and returning evaporation mother liquor and the evaporation condensate water to the step (3). The method is simple in process and low in cost, the utilization rate of sodium sulfate is larger than 95%, the purity of the sodium bicarbonate is larger than 96%, and the purity of the ammonium sulfate product meets the requirement of GB535.

Description

technical field [0001] The invention relates to the field of chemical technology, in particular to a novel method for preparing sodium bicarbonate from sodium sulfate and co-producing ammonium sulfate. Background technique [0002] Sodium bicarbonate is an important industrial and daily-use chemical. Sodium bicarbonate is generally produced from sodium chloride through the Solvay method or combined alkali-making method, and the raw material sodium chloride is mostly obtained by drying and refining seawater or by salt wells. With the substantial increase in the demand for soda ash in industrial production, the raw material of sodium chloride is in a tense situation. At the same time, my country produces a large amount of sodium sulfate. According to statistics, my country's annual by-product sodium sulfate reaches more than 10 million tons, while the sales volume of sodium sulfate is less than 50%. A large amount of sodium sulfate is surplus and stored in the storage yard, ...

AI Technical Summary

Problems solved by technology

However, due to the low conversion rate of sodium sulfate metathesis reaction, the utilization rate of sodium sulfate is less than 60%, and the ammonium sulfate with pure phase cannot be obtained, and the cost is high, so that the technology of sodium sulfate to prepare soda ash is at a standstill

CN101544385A discloses a kind of method that takes sodium sulfate as raw material and supplements organic amine to prepare sodium carbonate co-production calcium sulfate, this method draws lessons from the process route of former Soviet Union, can realize that the transformation rate of sodium reaches more than 90%; But organic amine boiling point is high , high viscosity, high energy consumption for evaporation and recovery; more organic amines are entrained in sodium bicarbonate and calcium sulfate, difficult recovery, more losses, and high production costs

CN104355326A, CN102198953A, CN202016881U disclose a kind of method that double decomposition method prepares sodium bicarbonate to co-produce ammonium sulfate, and this method uses sodium sulfate and ammonium bicarbonate as raw material, obtains sodium bicarbonate by double decomposition reaction, and the mother liquor that separates obtains deamination through high temperature , 130 ℃ evaporation and concentration to obtain sodium sulfate crystals, after separation, the mother liquor is cooled and crystallized to obtain the double salt of sodium sulfate and ammonium sulfate, and the mother liquor is evaporated and crystallized to obtain ammonium sulfate product. , high energy consumption, low utilization rate of sodium ions and sulfate radicals, large evaporation depth, large material circulation volume, high production cost, and no industrialized precedent at present

The cooling temperature of this method is too low, the optimal cooling temperature is -5°C to -2°C, the energy consumption is high, and the overall yield is low, the utilization rate of sulfate is only about 25%, the material circulation is large, and the production and operation cost is high , so far failed to achieve industrialization

CN105000579A, CN105712382A have announced a kind of precipitation method, and this kind method prepares sodium bicarbonate by double decomposition reaction of ammonium bicarbonate and sodium sulfate, then adds lime in sodium bicarbonate mother liquor, reclaims wherein ammonia, but the recovery rate of this process ammonia is only There are about 50%, resulting in waste of resources and increasing operating costs, and the calcium sulfate produced has large output, low value, poor quality, difficult sales, and easy to cause secondary pollution

CN103754898A discloses a kind of method that utilizes sodium sulfate and calcium chloride to prepare sodium chloride and combine combined soda making method to produce sodium carbonate, the method uses sodium sulfate and calcium chloride as raw materials, and obtains sodium chloride solution and calcium sulfate through metathesis reaction solid, and then produce sodium carbonate through the combined soda production method. This method is simple and easy to implement, and the process is mature, but it still does not bypass the generation of new solid waste calcium sulfate, and has not been popularized and applied.

[0005] As can be seen from the above analysis, the current technology for preparing sodium bicarbonate from sodium sulfate has problems such as complicated process, low sodium utilization rate, and low purity of ammonium sulfate.

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