Ammonium chloride dry rolling granulation process and unit

1. Physical properties of ammonium chloride:

Ammonium chloride, also known as brine sand, is a colorless cubic crystal or white crystalline powder. The taste is salty, cool, and slightly bitter. It dissolves in water and appears acidic, The pH value is generally around 5.6. The relative molecular weight is 53.49, the relative density is 1.527, and the refractive index is 1.642. Easy to dissolve in water, slightly soluble in ethanol, soluble in liquid ammonia, insoluble in acetone and ether. When heated to 100 ℃, it begins to significantly evaporate. At 337.8 ℃, it dissociates into ammonia and hydrogen chloride, and when cooled, it recombines to form extremely small particles of ammonium chloride, resulting in white thick smoke that is not easy to sink and is highly insoluble in water. Heat to 350 ℃ for sublimation, with a boiling point of 520 ℃. Low moisture absorption, but can also absorb moisture and form lumps in humid and rainy weather. Powdered ammonium chloride is highly hygroscopic, especially wet ammonium, with a moisture absorption point generally around 76%. When the relative humidity in the air exceeds the moisture absorption point, ammonium chloride undergoes moisture absorption and is prone to clumping. Hydrochloric acid and sodium chloride can reduce their solubility in water. Their solubility in water is 29.4g at 0 ℃, 33.2g at 10 ℃, 37.2g at 20 ℃, 41.4g at 30 ℃, 45.8g at 40 ℃, 50.4g at 50 ℃, 55.3g at 60 ℃, 60.2g at 70 ℃, 65.6g at 80 ℃, 71.2g at 90 ℃, and 77.3g at 100 ℃. The aqueous solution is weakly acidic, and the acidity increases when heated. Corrosive to black metals and other metals, especially copper, but has no corrosive effect on pig iron. It is a quick acting nitrogen chemical fertilizer with a nitrogen content of 24% to 25%, belonging to physiological acidic fertilizers. Can be used as a fertilizer, belonging to nitrogen fertilizer, but ammonia fertilizer cannot be applied together with alkaline fertilizer, and it is best not to apply it in saline alkali land to avoid reducing fertilizer efficiency.

2. Production of ammonium chloride:

Ammonium chloride is a co product of alkali production and is closely related to the soda ash industry. One ton of alkali is co produced with approximately one ton of ammonium chloride. In recent years, China's soda ash enterprises have developed rapidly. The production capacity of ammonium chloride has exceeded 5 million tons per year since 2005, and the production capacity of the equipment exceeded 10 million tons per year in 2008, with an average annual growth rate of 26%. As of 2013, the capacity of China's alkali plant has expanded to 16 million tons per year, and the production capacity of ammonium chloride has increased by more than 15%. There will still be some new production capacity investment in 2014 and the following years. The concentration of ammonium chloride production enterprises in China is relatively high, with six provinces and cities including Sichuan Chongqing, Jiangsu, Henan, Hunan, and Hubei accounting for 78% of the national ammonium chloride production, which has a significant impact on the national ammonium chloride industry.

3. Market for ammonium chloride:

In terms of the use of ammonium chloride fertilizer, it can be applied directly or used as a raw material for compound fertilizers. In terms of fertilizer utilization, nitrogen fertilizer is divided into base fertilizer and topdressing, requiring multiple fertilizations, while phosphorus fertilizer and potassium fertilizer are mainly used as base fertilizers. Therefore, base fertilizer usually requires compound fertilizer, while topdressing mainly applies nitrogen fertilizer. In addition, the total amount of nitrogen fertilizer in the world is 2-4 times that of phosphorus fertilizer, so the compounding rate of nitrogen fertilizer is relatively low, while the compounding rate of phosphorus fertilizer and potassium fertilizer is relatively high. The average compounding rate of nitrogen fertilizers in the world is only about 15%, while in the United States it is 19-20% and in Western Europe it is only 16%. However, the compounding rate of phosphorus fertilizers in both the United States and Western Europe is over 90%.

As shown above, the compounding rate of nitrogen fertilizers in developed regions is less than 20%, while in China it is around 13%, which means more than 80% of nitrogen fertilizers are directly applied. Due to the fact that the total nitrogen content of ammonium chloride accounts for only 3% of the total nitrogen fertilizer in the country, and the nitrogen fertilizer demand in regions and crops suitable for ammonium chloride (such as southern rice) is much higher than this value, the market capacity of ammonium chloride can be said to be vast as a direct fertilizer and an alternative to urea and ammonium bicarbonate. To open up the direct fertilization market for ammonium chloride, the first step is to improve the physical properties of ammonium chloride products, that is, to produce large particles of ammonium chloride.

4. Excellent properties of large particle ammonium chloride

The key factors affecting the use of fertilizers include not only fertilizer efficiency, but also storage, transportation, and handling performance. Powdered fertilizers have many drawbacks, such as segregation, difficulty in controlling clumping, poor flowability, difficulty in achieving mechanized fertilization, and easy formation of dust and loss during application. One way to solve the above problems is to achieve granulation of fertilizers. Granular fertilizers have good physical properties, do not generate dust during loading and unloading, do not clump when stored for a long time, have good fluidity, are easy to spread during fertilization, and can meet the requirements of airplane sowing and reducing losses. At the same time, they can also have a slow-release effect, improving the utilization rate of fertilizers. In addition, different but similar sized granular fertilizers can be directly mixed to obtain low-cost mixed fertilizers (BB fertilizers) with the same fertilizer efficiency as compound fertilizers. Therefore, the granulation technology of fertilizers at home and abroad continues to develop, and products such as large particle urea, ammonium phosphate, compound fertilizer, and granular potassium fertilizer are developing rapidly. Currently, granular fertilizers account for about 35% of the total amount of fertilizers in the world. In economically developed regions such as Europe and America, mechanized fertilization is more common, requiring fertilizer granulation and compounding. For example, in the United States, 40% of potassium fertilizer production is further processed into granular potassium. Granular fertilizers account for about 60% of the total consumption of fertilizers.

Ammonium chloride is more suitable for rainy areas in the south and humid climates in Southeast Asia. Powdered fertilizers are prone to moisture absorption and compaction, while granular fertilizers are superior to powdered fertilizers and have longer fertilizer efficiency. Therefore, granular ammonium chloride is an effective way to explore the direct fertilization market in the south.

5. Production process of large particle ammonium chloride:

The process of powder agglomeration into dense and hard plates under pressure is called extrusion; The process of crushing and sieving the plates into granular materials is called granulation. The function of squeezing is to expel the air between particles, and to bring the distance between particles close enough to generate attractive forces such as van der Waals forces, adsorption forces, crystal bridges, and embedded connections. The strength of extruded granules is mainly formed by the intermolecular forces between molecules.

The dry rolling granulation process has the following characteristics:

1. Low energy consumption:Roll granulation is the process of granulating materials at room temperature, and compared to other granulation methods, it does not require drying measures such as fuel or gas. Production only requires electricity consumption, with each ton of product consuming only about 30kWh of electricity.

2. No need to add adhesive:Other granulation processes are mostly wet processes that require a drying process, resulting in high energy consumption and high product moisture content. Dry granulation does not require additional additives and only utilizes the intermolecular forces of the material itself, simplifying the process and reducing energy consumption.

3. Low investment:Due to the elimination of the drying process and the simple process flow, the investment is relatively low. The system mainly consists of four parts: (1) powder pretreatment; (2) Roll pressing; (3) Consolidation and fragmentation; (4) Processing after granulation.

4. Wide range of abilities:For roll granulation equipment, the capacity ranges from 1 ton/hour Up to 50 tons per hour Taiwan can carry out more economical designs, so it has a wide range of applicable capabilities.

5. The shape of roll granulationIt is an irregular particle that does not affect the application of fertilizers. If necessary, a trimming process can be added to further round the particles. Fertilizer produced by extrusion granulation has sufficient strength, less dust, no clumping, narrow particle size distribution range, and good flowability.