No matter which process is used to produce any grade of ternary compound fertilizer, it must contain basic raw materials of nitrogen, phosphorus and potassium. The following introduces the raw materials commonly used in the production of npk compound fertilizers in most countries.
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Urea for npk fertilizer production
Physical characters
Urea CO(NH2)2, namely carbonic diamide (urea), colorless or white crystal, odorless, salty taste, density (20C) 1.335g/cm, melting point 132.4C, soluble in water, alcohol, insoluble in ether, chloroform. Pure urea contains 46.6% nitrogen.
Why urea can be the basic fertilizer for compound fertilizer production?
Urea has the highest nitrogen content among solid nitrogen fertilizers, and the nitrogen it contains is easily absorbed by plants.
In terms of its ability to be absorbed, it is comparable to nitrogen in ammonium phosphate.
As a fertilizer, urea is better than ammonium nitrate, has no explosion hazard, and has less hygroscopicity. The hygroscopic point of urea at 20 degrees celsius is not serious, and the hygroscopic point is 80%, while that of ammonium nitrate is 67%. When urea is used as a raw material for compound fertilizer production, it is easy to granulate due to its high nitrogen content, but it is easy to agglomerate due to high temperature during the drying process.
Superphosphate as raw materials for npk manufacturing
Superphosphate is a light gray or dark gray powder. Its main components are calcium dihydrogen phosphate monohydrate [Ca(H2P04)2. H20] and anhydrous calcium sulfate (CaSO4), a small amount of calcium sulfate hemihydrate CaSO4*0.5H2O and silicic acid SiO2*nH2O and undecomposed minerals, etc. In addition, it also contains phosphoric acid, free water, fluorosilicic acid, fluorosilicate and the like.
The active ingredient of superphosphate is P2O5, about 12% to 20%, most of which are soluble in water. It has quick effect after fertilization, and it belongs to the quick-acting phosphorus fertilizer mainly based on water-soluble phosphorus.
Why use it as raw materials for compound fertilizer production?
Superphosphate is the main phosphate fertilizer used in plants, and it is the main fertilizer that provides phosphorus for plants to generate. Plants need phosphorus to grow and make starches, proteins, and sugars. Therefore, plants cannot grow without phosphorus. When crops are deficient in phosphorus, they will grow slowly, fall leaves quickly, mature late, and yield low yields. According to statistics, applying 10~20kg of superphosphate per mu of land can increase the yield of grain by 1~1.5kg, soybean 0.8~1.2kg, cotton 0.3~1.2kg, wheat 0.6~2.3kg, corn 1~1.5kg per kilogram of superphosphate. kg, broad bean 0.5~1kg, rapeseed 0.8~1.3kg.
The fertilizer effect of superphosphate is different under different soil conditions, which is mainly affected by the acidity and alkalinity of the soil. In acidic soil (pH value is 4~5) or in alkaline soil (pH value is above 7), the application of superphosphate is effective, but it is not obvious in Huangnishan and calcareous soils.
The fertilizer effect of superphosphate alone is poor, and the application effect of ammonium nitrogen fertilizer and organic fertilizer is more obvious.
Calcium magnesium phosphate fertilizer as compound fertilizer production materials
Calcium magnesium phosphate fertilizer is a slightly alkaline vitreous fertilizer, which belongs to citric acid soluble phosphate fertilizer. The main components of calcium magnesium phosphate fertilizer are CaO, MgO, P2Os and SiO2. CaO and P2O5 come from phosphate rock, while MgO and SiO2 are compounded from other raw materials.
The calcium magnesium phosphate fertilizer powder is fine and dry. It is used to produce compound fertilizer. The process is simple and does not need to be crushed. Moreover, adding an appropriate amount of acid to react, the heat of reaction generated can evaporate water. Therefore, it is often not necessary to use a drying device to produce compound fertilizer.
Calcium magnesium phosphate fertilizer can be applied directly or used to make compound fertilizer in the npk plant. Calcium magnesium phosphate fertilizers cannot be mixed with ammonium sulfate because ammonia is lost in the reaction.
Potassium chloride for npk manufacturing process
Potassium chloride is a physiologically acidic water-soluble quick-acting fertilizer, which can significantly improve the yield of most crops. Because potassium chloride has a large content of chloride ions. For some chlorine-avoiding crops, such as tobacco, sugarcane, potato, the quality of tea, etc. is unfavorable. Therefore, when using potassium chloride as a potassium source to produce compound fertilizers, the concentration of chloride ions must be marked on the package.
Potassium chloride is the main variety of potash fertilizer, accounting for 90% to 94% of the amount of potash fertilizer. Potassium chloride can significantly increase the yield of crops. It can be used as top-dressing fertilizer or base fertilizer, and it can be applied singly or mixedly. It is the main raw material for the production of compound fertilizer.
Each package of commercially available potassium chloride fertilizer weighs 50kg, the inner layer is a plastic film, and the outer layer is a fiber bag.
Potassium sulfate as based fertilizer used in compound fertilizer production line
Potassium sulfate K2SO4 is a high-efficiency chlorine-free potassium fertilizer. As a fertilizer, potassium sulfate generally contains 46% to 52% potassium oxide. The melting point of potassium sulfate is 1074 °C, and the relative density is 2.66. At 0 °C, 6.85 g of potassium sulfate can be dissolved in every 100 g of water, and 24.1 g of potassium sulfate can be dissolved at 100 °C. The aqueous solution of potassium sulfate is neutral, and when heated with sulfuric acid, potassium sulfate becomes the acid salt KHSO4.
Commercial potassium sulfate, some are made into granules, the product is stable, does not absorb water, and does not agglomerate; some are in the form of potassium and magnesium powder as a product. Potassium magnesium powder is a double salt of potassium sulfate and magnesium sulfate, containing about 27% potassium oxide and 12% magnesium oxide.
Potassium sulfate is a physiologically acidic fertilizer. After use, some sulfate roots remain in the soil to acidify the soil. Long-term application will affect the harvest of crops. Therefore, in the soil with more potassium sulfate, it is advisable to add an appropriate amount of lime or other slightly alkaline fertilizers to neutralize the acidity of the soil.
Since potassium sulfate does not contain chloride ions, it is the most ideal potash fertilizer for the production of compound fertilizers for various chlorine-avoiding crops. For example: special compound fertilizer for tobacco, special compound fertilizer for potato, citrus, sugar cane, etc.
Ammonium chloride for compound fertilizer npk production
Ammonium chloride has low hygroscopicity, is not easy to agglomerate, and is easy to use. Ammonium chloride was used as fertilizer in agriculture earlier. Because ammonium chloride contains chloride ions, it is rarely used in chlorine-avoiding plants, such as sugar cane and potatoes. Ammonium chloride can be used in crops such as hemp, flax, rice, and wheat. Ammonium chloride is used to produce compound fertilizer, which is easy to granulate and not easy to agglomerate when dried. Therefore, at present, most of the ammonium chloride is used as the nitrogen source of compound fertilizer, which not only makes the process easy, but also lowers the product cost.
Ammonium sulfate for compound fertilizer manufacturing
Ammonium sulfate is one of the commonly used nitrogen fertilizers. It is not easy to agglomerate and has low hygroscopicity, and is especially suitable for use as a raw material for the production of compound fertilizers. Ammonium sulfate is a physiologically acidic fertilizer. When ammonium sulfate is applied to the soil, the sulfuric acid in the soil is left in the soil, causing acidity.
Therefore, after long-term application of ammonium sulfate in the soil, some alkaline fertilizers, such as lime, must be applied to neutralize the acidity of the soil. Calcium sulfate is more suitable for crops such as oats, cotton, potatoes, hemp, and kohlrabi.
Ammonium bicarbonate used in npk manufacturing plant
Ammonium bicarbonate is a neutral fertilizer suitable for various crops and various soils.
Ammonium bicarbonate is easily decomposed and lost. Under normal conditions (20°C), the weight is reduced by about 0.3% after one day and night, about 4% after 5 days, about 9% after 10 days, and when the temperature is 30°C, the loss of 10% on 5 days.
Ammonium bicarbonate has strong hygroscopicity and low nitrogen content, so it must be specially treated as a compound fertilizer raw material.
In addition to the above-mentioned raw materials, there are many other raw materials in the production of compound fertilizers, such as sulfuric acid, stone powder, phosphoric acid, organic fertilizers, slow-release agents, etc.
Monoammonium phosphate for high and medium concentration ternary compound fertilizers production
Monoammonium phosphate is a compound fertilizer mainly composed of phosphorus and nitrogen. It is an important raw material for the production of high and medium concentration ternary compound fertilizers. Monoammonium phosphate has little hygroscopicity, and will not cause ammonia loss when heated to about 100 °C, and hydrate will not occur in the range of 0~100 °C. At 19℃, the relative density is 1803kg/m3, the pH value of 0.1mol solution is 4.4, and it is soluble in water. At 25℃, the solubility in water is 40.
Diammonium phosphate for npk fertilizer production process
Diammonium phosphate is a fertilizer mainly composed of phosphorus and nitrogen. It is suitable for various soils and various crops. It is the raw material for the production of high and medium concentration ternary compound fertilizers. Diammonium phosphate is alkaline, the pH value of 0.1mol solution is 7.8, it has good stability, it will decompose into monoammonium phosphate at 70℃, the density is 1619kg/m’ at 19℃, and the solubility is 72.1 at 25℃. Diammonium phosphate should not be mixed with alkaline fertilizers such as plant ash, lime nitrogen, and lime to avoid fertilizer failure. The packaging of diammonium phosphate is the same as that of monoammonium phosphate.
Borax used in the compound fertilizer production process
Borax is a colorless translucent or white monoclinic crystalline powder, odorless, salty, with a relative density of 1.73. It loses 8 crystal waters at 60°C, loses all crystal water at 350~400°C, and is easily soluble in water. The aqueous solution is weakly alkaline and easily weathered in dry air. Borax is the main raw material for providing boron for the production of compound fertilizers, sacks or kraft paper for packaging.
Boric acid for compound fertilizer production
Boric acid is an odorless triclinic crystal powder with pearl luster, the relative density is 1.435 (15℃), soluble in water, the aqueous solution is acidic, and also soluble in glycerol and ethanol. The use of boric acid in agriculture is the same as that of borax, both of which provide the trace element boron, which can be used to form compound fertilizers with other nutrients, or can be used alone. The boric acid has a long fertilizer effect, and one application can last for 2 to 3 years. The external fertilization is foliar spraying. The spraying liquid is 30 to 5 kg per mu, and the concentration is 0.1% to 0.15%. The concentration of fruit trees can be appropriately larger. Boric acid is toxic to the human body, and it affects the nerve center when taken orally. Pay special attention when using it. Boric acid is packed in kraft paper or plastic bags, and the outer layer is sacks. It cannot be stacked with wet items and other colored items.
Zinc sulfate for compound fertilizer production factory
Zinc sulfate, also known as Hao alum, zinc alum, is anhydrous needle crystal or powder crystal, zinc sulfate heptahydrate contains 23% zinc, zinc sulfate monohydrate contains 36% zinc, relative density: zinc sulfate monohydrate 3.31, heptahydrate Zinc sulfate 1.957, heptahydrate is easily soluble in water, slightly soluble in ethanol and glycerol, loses a crystal water at 39°C, loses crystal water when heated to 280°C, and decomposes into zinc oxide and sulfur trioxide at 767°C. Zinc sulfate is mainly used as the production of zinc compound fertilizer to supplement the deficiency of soil zinc. Zinc fertilizer can be used for a variety of plants, including rice, corn, flax, cotton, sugar beets, fruit trees, etc. Zinc sulfate can also be used for external fertilization, that is, compounded into a multi-element foliar fertilizer, with good results. Application (when compound fertilizer) zinc sulfate should not be mixed with alkaline fertilizer or farmyard manure (such as ammonium bicarbonate, plant ash, etc.) to avoid hydrolysis.
Manganese sulfate for fertilizer compound production process
Manganese sulfate is a light rose red small crystal, easily soluble in water, insoluble in ethanol; the relative density is 2.95, the manganese content of pure manganese sulfate is 31%, usually with a crystal water, when heated to 200 ℃, the crystal water will be dehydrated. At 280°C, the crystal water will be completely removed, and it will start to decompose at 850°C, releasing SO3, SO2 or O2, and finally Mn304 is generated.
Manganese sulfate is mainly used as a raw material for the production of manganese compound fertilizers or applied to crops alone. Manganese is involved in photosynthesis, nitrogen conversion, carbohydrate transfer, etc. in crops. Manganese fertilizer can be applied to crops such as barley, corn, millet, sugar beet, potato, sweet potato, rapeseed, tobacco, soybean, peanut, mung bean, etc. The dosage per mu is 1 ~ 2kg. It can also be used for seed soaking, with a concentration of 0.01%~0.1% aqueous solution; it can also be poured, with a concentration of 0.1%~0.2% aqueous solution.
Ammonium molybdate for npk fertilizer production plant
Ammonium molybdate is a colorless or light-yellow prismatic crystal with a relative density of 2.38~2.98, soluble in water, strong acid and alkali, but insoluble in alcohol and acetone. It is easy to be weathered in the air to lose crystal water and ammonia. When heated to 90 °C, it loses one crystal water. At 190 °C, it is decomposed into ammonia, water and molybdenum trioxide. Ammonium molybdate is also used as a raw material for molybdenum-containing compound fertilizer. Molybdenum directly participates in the nitrogen transformation and nitrogen fixation of crops. Only the presence of molybdenum can promote the synthesis of protein in crops. Molybdenum is particularly effective for soybeans, peanuts, broad beans, rape and other crops. Ammonium molybdate is usually packed in iron drums lined with plastic bags and cannot coexist with acids.
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