Method for preparing sodium carbonate and co-producing ammonium sulfate by using sodium sulfate

Abstract

The invention provides a method for preparing sodium carbonate and co-producing ammonium sulfate by using sodium sulfate, which comprises the following steps: (1) mixing sodium sulfate, ammonium bicarbonate recovery liquid, ammonium bicarbonate solid or mixed gas of ammonia gas and carbon dioxide, and carrying out double decomposition reaction to obtain sodium bicarbonate and double decomposition mother liquor; calcining the obtained sodium bicarbonate to obtain sodium carbonate; (2) separating the double-decomposition mother liquor through a nanofiltration membrane to obtain ammonium bicarbonate recovery liquid and sulfate concentrated liquid; (3) mixing the double salt, the evaporation mother liquor and the sulfate concentrated solution, and heating and crystallizing to obtain sodium sulfate and double salt washing liquor; (4) cooling and crystallizing the double salt washing liquid to obtain double salt and an ammonium sulfate-rich solution; and (5) evaporating and crystallizing the ammonium sulfate-rich solution to obtain ammonium sulfate and evaporation mother liquor. According to the method provided by the invention, the problem of excessive sodium sulfate is relieved, high-value utilization of sodium sulfate is realized, meanwhile, energy consumption is reduced, the technological process is simplified, and both environmental protection property and economical efficiency are taken into account.

Description

technical field [0001] The invention belongs to the technical field of alkali production, and relates to a method for preparing sodium carbonate by utilizing sodium sulfate, in particular to a method for preparing sodium carbonate and co-producing ammonium sulfate by utilizing sodium sulfate. Background technique [0002] Sodium sulfate is a basic chemical raw material, mainly used in synthetic detergents, production of sodium sulfide, textile printing and dyeing and glass manufacturing. According to data released by the National Bureau of Statistics, in 2019, the proven resource reserves of mirabilite (sodium sulfate decahydrate) in China were 119.06 billion tons, ranking first in the world. The sodium sulfate produced with mineral thenardite as raw material has high purity and low cost. Another source of sodium sulfate is produced in the form of by-products in various chemical production processes, such as acid-base neutralization, sodium vanadium extraction, non-ferrous ...

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Problems solved by technology

Because this method needs to pass through excessive carbon dioxide, it will produce carbon dioxide waste gas, and there will also be a small amount of calcium carbonate in the gypsum, which will reduce the quality of gypsum, and the solubility of sodium bicarbonate is very low, so it is necessary to introduce an excessive amount of water in the whole system. Calcium residues, subsequent use of sodium bicarbonate for desulfurization can easily cause severe scarring of the reactor

[0004] CN112850747A discloses a kind of method and device for preparing ammonium sulfate and sodium bicarbonate with sodium sulfate and ammonium bicarbonate, described method is provided with a plurality of anion-cation exchange membranes in the electrodialysis unit in electric field, sodium ion, sulfate ion , ammonium ions and bicarbonate ions are recombined to form ammonium sulfate solution and sodium bicarbonate solution, but this method and device have strict requirements on the raw materials. If the raw materials contain chloride ions, metal ions or organic matter, it will not only affect the product quality adverse effects and damage to equipment

In addition, due to the complex structure of electrodialysis equipment, the operation is relatively cumbersome, and the maintenance and replacement costs of later equipment are high.

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