Method for co-producing sodium bicarbonate and ammonium sulfate from sodium sulfate

Abstract

The invention provides a method for co-producing sodium bicarbonate and ammonium sulfate from sodium sulfate, which comprises the following steps: carrying out double decomposition reaction on sodiumsulfate and ammonium bicarbonate under the action of an accelerator to obtain the sodium bicarbonate and the ammonium sulfate. The method is simple in process and low in cost, the utilization rate ofsodium sulfate is higher than 85%, the purity of sodium bicarbonate is higher than 90%, and the purity of the ammonium sulfate product meets the requirements of GB535-1995.

Description

technical field [0001] The invention belongs to the field of alkali production and secondary resource recovery, and in particular relates to a method for preparing sodium bicarbonate and co-producing ammonium sulfate with sodium sulfate as a raw material. [0002] technical background [0003] With the strict requirements of the chemical industry on environmental protection, the discharge of high-salt wastewater containing sodium sulfate is no longer allowed; the conventional treatment process is high-salt wastewater evaporation and crystallization to precipitate waste sodium sulfate, and the evaporated condensed water is returned to the production system for reuse. At present, the annual production of sodium sulfate in my country is expected to exceed 10 million tons, and its low added value and narrow application fields lead to a large amount of stockpiling. Waste sodium sulfate is a soluble salt, which is easy to enter the soil and rivers under the erosion of rainwater, th...

AI Technical Summary

Problems solved by technology

The process of this method is complex, the required equipment is many and huge, and the investment in building a plant is huge, and in the gas-liquid phase reaction process carried out in the carbonization tower, ammonia and Na + The utilization rate of the factory is only 64-65%, the factory cost is high, and the economic benefit is poor

The heavy alkali crystals produced by the gas-liquid phase reaction in this method are fine, which brings very unfavorable factors to the separation, washing and calcination processes.

[0008] Scientists in the former Soviet Union once added organic amines to the reaction system of preparing sodium carbonate from sodium sulfate to promote the metathesis reaction, which can increase the conversion rate to more than 90%. However, because this type of organic matter is soluble in water, it is extremely difficult to separate the organic matter. Moreover, due to the residue of organic matter in ammonium sulfate and sodium carbonate, it is difficult to sell the product; in addition, the loss of organic amine in the production process is large, and the production cost is too high

[0009] CN101544385A discloses a kind of method that takes sodium sulfate as raw material and supplements with organic amine to prepare sodium carbonate co-production calcium sulfate, this kind of 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 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

[0010] CN104355326A, CN102198953A, CN202016881U disclose a kind of method that double decomposition method prepares sodium bicarbonate to co-produce ammonium sulfate, 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 is decomposed by high temperature. Ammonia, evaporated and concentrated at 130°C to obtain sodium sulfate crystals. After separation, the mother liquor was cooled and crystallized to obtain the double salt of sodium sulfate and ammonium sulfate, and the mother liquor was evaporated and crystallized to obtain ammonium sulfate. and other processes, high energy consumption, low utilization rate of sodium ions and sulfate radicals, large evaporation depth, large material circulation, and high production costs. There is currently no industrialized precedent

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 operation High cost, so far, there is no precedent for industrialization

[0012] A kind of precipitation method is disclosed in CN105000579A, CN105712382A, and this 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

Disclosed in CN103754898A is a method of utilizing sodium sulfate and calcium chloride to prepare sodium chloride in conjunction with the combined alkali-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 solid, and then produce sodium carbonate through the combined soda production method. This method is simple and easy, 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.

[0013] Although the above-mentioned documents disclose the preparation methods of some sodium bicarbonate and ammonium sulfate, there are still complex preparation processes, low raw material utilization, high cost, and insufficient product purity. Therefore, a short process, good sodium sulfate conversion rate, and The technical route of low cost and high purity of the prepared sodium bicarbonate and ammonium sulfate is still of great significance

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