Background and overview[1-3]
Ammonium chloride, molecular formula NH4Cl, is colorless cubic crystal or powder. It tastes cool and sublimates or decomposes when heated. In humid and rainy weather, it absorbs moisture and clumps. It is easily soluble in Water, soluble in glycerin, slightly soluble in alcohol, insoluble in acetone and ether. It can be divided into pharmaceutical grade ammonium chloride, industrial grade ammonium chloride, agricultural grade ammonium chloride, and reagent grade ammonium chloride. Among them, pharmaceutical grade ammonium chloride is an expectorant, cough reliever, and diuretic; industrial ammonium chloride is mainly used in dry batteries, batteries, ammonium salts, tanning, electroplating, medicine, photography, electrodes, adhesives, etc.; agricultural grade chlorine Agricultural ammonium chloride is a nitrogen fertilizer with a nitrogen content of more than 25%. It is suitable for neutral and calcareous soils and has a significant effect on increasing the yield of rice, corn, wheat, cotton, millet, rape, hemp and other crops. ;Reagent grade ammonium chloride is used for metal welding, electroplating, tanning and making dry batteries.
Purification method[1-2]
Report 1,
(1) Weigh 800g of deionized water, weigh 524.8g of industrial grade ammonium chloride according to the solubility of ammonium chloride at 80°C, and place the beaker containing deionized water and ammonium chloride in a constant temperature water bath Heat to 80°C and stir continuously to completely dissolve the ammonium chloride to obtain a saturated ammonium chloride solution;
(2) Place the saturated ammonium chloride solution at room temperature and slowly cool it down to crystallize the ammonium chloride. When the temperature reaches room temperature, place it in a low-temperature constant-temperature water bath and continue crystallization until the temperature reaches 5°C;
(3) Filter the ammonium chloride crystallized in step (2) through a sand core funnel while maintaining the crystallization temperature to obtain ammonium chloride crystals. The ammonium chloride mother liquor obtained by filtration is collected for processing;
(4) Elute the ammonium chloride crystals obtained in step (3) with a saturated ammonium chloride solution at 5°C for 1 minute to collect the ammonium chloride crystals;
(5) Slowly heat and dissolve the ammonium chloride crystals obtained in step (4) according to the method of step (1), and then slowly lower the temperature at room temperature to crystallize the ammonium chloride. When the temperature reaches room temperature, place Put it into a low-temperature constant-temperature water bath and continue cooling and crystallizing until the temperature reaches 5℃;
(6) Elute the ammonium chloride crystals obtained in step (5) with a saturated ammonium chloride solution at 5°C for 1 minute to collect the ammonium chloride crystals;
(7) Concentrate the collected ammonium chloride crystals with pure hot air and dry them to obtain high-purity ammonium chloride.
Report 2,
A method for improving the quality of industrial ammonium chloride products, the steps are as follows,
(1) First use 50°C water to dissolve ammonium chloride into a saturated solution of ammonium chloride, in which the content of sulfate ions SO4 2- in ammonium chloride is about 0.05%;
(2) Then cool the saturated ammonium chloride solution to 12°C to precipitate ammonium chloride crystals;
(3) Pass the ammonium chloride crystal liquid through a thickener to increase the solid-liquid ratio. When the solid-liquid ratio reaches 16:84, enter the centrifuge for dehydration and drying to obtain the finished ammonium chloride. The content of sulfate ion SO4 2- is about 0.01%;
(4) Add a barium chloride solution that is not excessive relative to the sulfate radicals in the mother liquor I to the mother liquor I thrown out during dehydration by the centrifuge to generate a barium sulfate precipitate and then filter it to obtain the filtered mother liquor II. After the mother liquor II is heated to 50°C, it is then used to dissolve ammonium chloride and recycled.
The first step can be carried out in a hot liquid container. After it is fully dissolved into a saturated ammonium chloride solution, it is cooled by heat exchange through a heat exchanger, and then enters the cold liquid container to precipitate ammonium chloride crystals. In the fourth step, after the mother liquor II is heated to 50°C, it is then put into the hot liquid container of the first step to dissolve ammonium chloride and recycled.
References
[1] [Chinese invention] CN202010930681.7 A method for producing high-purity ammonium chloride from industrial-grade ammonium chloride
[2] [China invention, China invention authorization] CN02157284.4 A method for improving the quality of industrial ammonium chloride products
[3] [Chinese invention] CN200810045097.2 Preparation method of large particle crystalline ammonium chloride
