Device for preparing ammonium chloride through co-production of baking soda

Abstract

The invention discloses a device for preparing ammonium chloride by co-production of baking soda, which comprises a first-stage baking soda precipitation device and a first solid-liquid separation device which are communicated in sequence, an ammonium chloride preparation device, a second-stage baking soda precipitation device and a mother liquor circulation device which are communicated in sequence, and a sodium precipitation device and a second solid-liquid separation device, the sodium precipitation device comprises a first sodium precipitation kettle and a second sodium precipitation kettle which are sequentially communicated, the top end of the first sodium precipitation kettle is connected with a salt metering scale, the feeding end of the first sodium precipitation kettle is connected with the first solid-liquid separation device, and the discharging end of the second sodium precipitation kettle is communicated with the second solid-liquid separation device; and the second solid-liquid separation device is respectively communicated with the ammonium chloride preparation device and the first-stage baking soda precipitation device. According to the method, the phenomenon that baking soda and ammonium chloride generated by residual ammonium bicarbonate and sodium chloride in the cold separation process are difficult to separate can be avoided, the content of sodium salt in ammonium chloride is reduced, the content of ammonia in ammonium chloride is increased, and the yield of baking soda and ammonium chloride is increased.

Description

technical field [0001] The invention relates to the technical field of chemical production, in particular to a device for preparing ammonium chloride through combined production of baking soda. Background technique [0002] Baking soda, also known as sodium bicarbonate, is a kind of inorganic salt, white crystalline powder, odorless, alkali taste, soluble in water, widely used in pharmaceutical industry, food processing, fire fighting equipment and other industries. [0003] Ammonium chloride, referred to as ammonium chloride, refers to the ammonium salt of hydrochloric acid, mostly a by-product of the alkali manufacturing industry (such as baking soda), in the form of white or slightly yellow square or octahedral small crystals, available in powder and granular forms , easy to store, is widely used in agricultural fertilizers, batteries, electroplating, metal welding, dyes, printing and medicine. [0004] The preparation of baking soda in industry often uses sodium chlorid...

AI Technical Summary

Problems solved by technology

[0006] 1) The content of ammonium salt in the baking soda product prepared by this device is high. The reason is that in the later stage of the metathesis reaction, the concentration of sodium ions becomes thinner, and the metathesis reaction tends to ease from intense, forming an unsuitable sodium chloride and ammonium bicarbonate. The atmosphere of the metathesis reaction makes some of the ammonium bicarbonate lack reaction power and coexist with baking soda in the form of solid crystals, and enter the drying process together with baking soda after filtration and centrifugation. The temperature when drying the baking soda is 50 -60°C, ammonium bicarbonate crystals are difficult to decompose into free ammonia and volatilize at this drying temperature, and the ammonium salt content in the obtained baking soda product exceeds the standard; the other part of ammonium bicarbonate is directly dissolved and cannot be combined with the metathesis ions under low sodium conditions Collision forms crystal nuclei, resulting in slower formation of crystal nuclei and slower crystal growth, resulting in finer crystallization, which in turn will reduce the subsequent filtration effect and affect the yield of baking soda;

[0007] 2) The ammonium chloride prepared by this device has low nitrogen content and high sodium salt content. The reason is that the carbonate content in the mother liquor M1 after the separation of baking soda is high and high. Phase diagram Na, HCO 3 Crossing curves, NaHCO formed at low temperature 3 It cannot be separated from ammonium chloride, but together with ammonium chloride, it enters the ammonium chloride treatment device from the bottom of the crystallization tank and is brought into the ammonium chloride product, resulting in the increase of sodium salt and partial nitrogen content in the ammonium chloride product. Low; in addition, because a large amount of sodium chloride solid salts have been added in the salting-out kettle in the salting-out process, when the ammonium chloride crystal slurry that the salting-out kettle crystallizes out is directly input crystallization kettle through crystal slurry taking-out outlet, sodium chloride It will directly enter the crystallization tank with the ammonium chloride, causing the sodium ion in the ammonium chloride product crystallized from the crystallization tank to exceed the standard, making it difficult for the ammonium chloride to reach the agricultural standard and reducing the product quality of the ammonium chloride;

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