Applications of ammonium chloride_industrial additives

Background and overview^[1]

Ammonium chloride is a colorless equiaxed crystal that easily absorbs moisture and agglomerates. Ammonium chloride is weakly acidic when dissolved in water. When heated, the acidity increases and has a strong corrosive effect on metals. China’s soda ash industry widely adopts the Hou’s soda production method (co-alkali method) to produce ammonium chloride. Ammonium chloride is divided into two specifications: agricultural and industrial. The ammonium chloride content for agricultural use is greater than 96%, and the ammonium chloride content for industrial use is greater than 99%. China’s coking plant applies the principle of the combined alkali method to produce ammonium chloride using concentrated ammonia water, the product of coke oven gas purification, with a purity of 97%. Ammonium chloride is used for rice fertilization, and its fertilizer efficiency is better than ammonium sulfate. Agricultural ammonium chloride is dissolved in water and recrystallized to the specifications of industrial ammonium chloride, which can be used in electroplating, batteries, metal welding, printing and dyeing, printing and pharmaceutical industries.

Apply^[2-4]

1. Medicine: It can stimulate the gastric mucosa, reflexively excite the respiratory tract glands, promote the increase of bronchial gland secretion, make sputum thinner, make it easier to cough up, and exhibit an expectorant effect. It is suitable for animals with acute and chronic bronchitis and lung infection, and cases where the phlegm is thick and difficult to cough up. It has diuretic and urine acidification effects and can strengthen the diuretic effect. Oral administration: A dose of 1 to 2 grams for pigs, 2 to 5 grams for sheep, 10 to 25 grams for cattle, 8 to 15 grams for horses, and 0.2 to 1 grams for dogs. For cats, 20 mg per kilogram of body weight, 2 to 3 times a day. Notes are as follows: 1) This product is not compatible with sulfonamide drugs because this product can make urine acidic, and sulfonamide drugs have reduced solubility in acidic urine and tend to precipitate and crystallize. 2) After a large amount of ammonium chloride is absorbed by the body, it can make the blood acidic, so it is contraindicated in sick animals with symptoms of sepsis. 3) This product will decompose when exposed to alkali or heavy metal salts, so its incompatibility is contraindicated. 4) It should not be used on animals with severe liver and kidney dysfunction and gastric ulcer disease.

2. Food: Used as a food leavening agent (used together with sodium bicarbonate) and to make toffee, yeast nutrients, and dough conditioner. The application of ammonium chloride in food has attracted more and more attention in recent years. , demand is also showing a steady growth trend. Ammonium chloride is generally used as a dough conditioner mixed with sodium bicarbonate. The dosage is about 25% of sodium bicarbonate. Adding vitamin C and ammonium chloride mixture can make the dough have good elasticity, extensibility and mechanical processability, thus Make the bread have good volume, color, aroma and elasticity. Since consuming too much sodium chloride is obviously harmful to the body, a series of studies have shown that long-term excessive salt consumption not only causes and aggravates high blood pressure, but also causes kidney disease, aggravates diabetes, aggravates asthma, and is prone to osteoporosis and even fractures. Cause many chronic diseases such as gastric digestive system. In developed Western societies, mixtures of ammonium chloride, potassium chloride, partially hydrolyzed protein, and plant peptides are gradually used to replace table salt, making them a nutritious and functional condiment widely used in bread and biscuits. And in many countries and places, ammonium chloride and licorice are boiled into a flavoring agent (black crystal shape) and used in various foods (such as braised chicken in Finland, ragu rice in Sweden, Zote noodles in the Netherlands, blood in Denmark products, delicacies, etc.), and ammonium chloride is added as a flavoring agent to vodka.

3. Others: used in dry batteries, solders, printing and dyeing, tanning, medicine (diuretics, expectorants, gargles), electroplating (tin plating and galvanizing); chemical fertilizers (not suitable for chlorine-resistant crops, Such as sweet potatoes, tobacco, sugar beets).

Preparation^[3]

A method for producing high-purity ammonium chloride through multi-stage (three-stage) flash evaporation cooling and continuous crystallization, following the following steps in sequence:

1). Put 7500 kilograms of ammonium chloride (purity) with a weight content (purity) of 96.5% (a by-product of potassium carbonate produced by the ion exchange method) into 9000L tap water and heat it to 100~105℃ to obtain a temperature of 100~105℃ Saturated solution of ammonium chloride Ⅰ;

2). Filter the entire ammonium chloride solution I (approximately 15,000L) obtained in step 1 at a temperature of 100 to 105°C through a security filter with thermal insulation performance with a pore size of 5 microns (the purpose is to remove Insoluble substances), ammonium chloride solution II was obtained (after testing, the suspended solids were less than 0.5 mg/l, the concentration of ammonium chloride was approximately 43.2%, and the concentration of potassium chloride was 1.36%, Ca2+: 0.0012%, Mg2+: 0.0011%, Fe≤0.0005%, heavy metals ≤0.0005%). Note: The above % are all weight %.

3). Transport the ammonium chloride solution II with a temperature of 100 to 105°C to the DTB type I effect flash crystallizer through a feed pump at a flow rate of 15m3 per hour for flash cooling and concentration. The I-effect flash crystallizer uses a DTB type crystallizer. The temperature of the materials in the I-effect flash crystallizer is controlled at 76~80°C, the vacuum degree is controlled at -0.080Mpa~-0.086Mpa, and the circulation flow is the ammonium chloride in the crystallizer. 1 times the volume/hour of the slurry (i.e. the amount of material in the I effect flash crystallizer); until the obtained ammonium chloride slurry I contains ammonium chloride crystals accounting for 4.5% of the total weight of the ammonium chloride slurry I;

4) Ammonium chloride slurry I is transported to the II-effect flash crystallizer through a slurry forced circulation pump for flash concentration and cooling; the II-effect flash crystallizer uses a DTB type crystallizer; the II-effect flash crystallizer The temperature of the materials in the device is controlled at 48~52℃, and the vacuum degree is controlled at -0.094Mpa~-0.096Mpa; the circulation flow is 1 times the volume/hour of the ammonium chloride slurry in the crystallizer (the amount of material in the II effect flash crystallizer) ; Until the obtained ammonium chloride slurry II contains ammonium chloride crystals accounting for 10.6% of the total weight of ammonium chloride slurry II;

5) Ammonium chloride slurry II is transported to the III-effect flash crystallizer through a slurry forced circulation pump for flash cooling and crystallization. The III-effect flash crystallizer uses a DTB type crystallizer; the III-effect flash crystallizer is used The temperature of the materials in the crystallizer is controlled at 18~22℃, the vacuum degree is controlled at -0.098Mpa~-0.099Mpa, and the circulation flow is 1 times the volume of the ammonium chloride slurry in the crystallizer (the amount of material in the III effect flash crystallizer)/ hours; until the obtained ammonium chloride slurry III contains ammonium chloride crystals accounting for 16.8% of the total weight of ammonium chloride slurry III; Note: The secondary steam generated by the III-effect flash crystallizer is pumped through a steam jet compression pump Condensation, the tail gas is cooled by the standpipe condenser and then pumped away by the water circulation vacuum pump; the formed steam condensate can be returned to the boiler as pure water or reused in the production process; the steam injection compression pump uses the raw steam from the boiler as power to extract Secondary steam; since the flash evaporation temperature of the III-effect flash crystallizer is too low, it is no longer utilized.

6). Ammonium chloride slurry III is separated by centrifugation (the centrifugal speed is about 1200 rpm, the time is about 10 minutes), and 4140 kg of ammonium chloride wet product with a water content of 2.8% is obtained. The temperature is 20 A total of 11m3 of ammonium chloride mother liquor I at ℃. Among them, 10% (11m3*10%=1.1m3) of the ammonium chloride mother liquor I was moved out of the high-purity ammonium chloride production line as the raw material liquid for the production of agricultural ammonium chloride (thereby ensuring that the potassium chloride content in the ammonium chloride mother liquor I is less than 2.0%).

7). Dry the centrifuged 4140 kilograms of ammonium chloride wet product with a moisture content of 2.8% through a vibrating fluidized bed (the temperature during vibrating fluidized bed drying is 125°C), and pass through a 40-mesh sieve to obtain 4015 Kilogram of high-purity ammonium chloride finished product, the ammonium chloride content of the finished product is 99.8%, the sodium chloride content is 0.08%, the sulfate content is less than 0.003%, calcium and magnesium are both less than 0.0001%, heavy metals and arsenic are both less than 1ppm, water content It is 0.12% and the average particle size is 0.9mm.

Main reference materials

[1] Encyclopedia of Chinese Metallurgy·Coking Chemical Industry

[2] New Practical Veterinary Drug Manual

[3] CN201310590527.X Method for producing high-purity ammonium chloride by multi-stage flash cooling and continuous crystallization

[4] Practical Fine Chemical Dictionary