Ammonium Phosphate

Product Overview

Ammonium Phosphate (CAS: 7722‑76‑1) is a nitrogen‑phosphorus binary inorganic composite compound produced by the neutralization reaction of phosphoric acid and liquid ammonia. It is one of the world's most widely‑used high‑concentration fast‑acting nitrogen‑phosphorus raw materials. Commercially mainstream industrial grades include Monoammonium Phosphate (MAP, ammonium dihydrogen phosphate) and Diammonium Phosphate (DAP, diammonium hydrogen phosphate). Triammonium phosphate is extremely unstable at ambient temperature and atmospheric pressure; it readily decomposes to release ammonia gas and becomes inactive, hence it has no value for industrial production or commercial application.

The product normally appears as white crystalline granules or crystalline powder. It is odor‑free, features excellent water solubility, high nutrient purity and reliable impurity controllability. It is widely used in agricultural fertilization, industrial processing, food additives, flame‑retardant materials, new‑energy materials and other application scenarios.

Distinct physicochemical differences exist between the two mainstream products. The aqueous solution of monoammonium phosphate is weakly acidic; it has extremely low hygroscopicity, good anti‑caking property and outstanding thermal stability. The aqueous solution of diammonium phosphate is weakly alkaline with higher nitrogen content and faster fertilizer efficiency. Nevertheless, it is prone to moisture absorption and caking under high‑temperature and high‑humidity conditions, accompanied by slight ammonia volatilization and nutrient loss. Both products are non‑toxic, non‑flammable and non‑explosive. They are compliant general inorganic chemical raw materials and core base materials for high‑analysis compound fertilizers. China has a complete supporting ammonium phosphate industrial chain with sufficient production capacity and prominent cost‑performance, making ammonium phosphate a premium alternative to traditional low‑concentration phosphate fertilizers.

Basic Parameters

Production Processes of Ammonium Phosphate

(1) Conventional Process

First, phosphoric acid is concentrated. Wet‑process dilute phosphoric acid (P₂O₅: 28 %‑32 %) is vacuum‑concentrated to a P₂O₅ concentration of 45 %‑54 % for neutralization. Concentrated phosphoric acid reacts with gaseous ammonia in a pre‑neutralization reactor at an NH₃/H₃PO₄ molar ratio of approximately 1.4 (the solubility maximum point of ammonium phosphate) and a reaction temperature of around 115 °C, generating slurry with 16 %‑20 % moisture content.

Ammoniation granulation is carried out afterwards. The slurry is fed into a rotary drum granulator, and supplementary ammonia is added to adjust the molar ratio to 1.85‑2.0 for DAP or 1.0 for MAP. Reaction heat evaporates water and precipitates crystals, which are mixed with recycled feedstock for granulation, followed by cooling. Wet granules are sent to a rotary dryer with hot flue gas in co‑current flow until moisture content drops below 2 %. Qualified 2‑4 mm granules are screened out; coarse particles are crushed and fine powder returns to the granulator. Qualified granules are cooled to 45‑50 °C, coated and packed. Tail‑gas treatment is critical: ammonia and dust escaping from each working procedure are recovered by scrubbing with dilute phosphoric acid and returned to the pre‑neutralization reactor.

(2) Slurry Process

First, dilute phosphoric acid undergoes direct neutralization. Unconcentrated wet‑process dilute phosphoric acid (P₂O₅: 20 %‑30 %) directly reacts with gaseous ammonia in a neutralization reactor or tubular reactor to produce ammonium‑phosphate slurry.

Then comes slurry concentration. The neutralized dilute slurry is concentrated through multi‑effect evaporation (double‑effect or triple‑effect). As the core innovation of the slurry process, it changes from "concentrating phosphoric acid" to "concentrating slurry", achieving significant energy reduction.

Subsequently, granulation or spray‑drying is performed. Concentrated slurry can be sprayed onto recycled feedstock for granulation and drying to obtain granular products; spray‑drying yields powdered products. Ammonia and dust in tail gas are recovered via scrubbing, and crystal mother liquor is recycled to the neutralization or concentration system.

Difference between the two processes: whether phosphoric acid is concentrated prior to neutralization.

Grade Classification of Ammonium Phosphate

(1) Agricultural‑Grade Ammonium Phosphate

As high‑concentration nitrogen‑phosphorus compound fertilizers, agricultural‑grade monoammonium phosphate and diammonium phosphate serve as major raw materials for compound‑mixed fertilizers, accounting for 80 % of phosphate‑fertilizer consumption in China. The aqueous solution of monoammonium phosphate has a pH value of 4.4‑4.8 and is weakly acidic, suitable for alkaline soils. The aqueous solution of diammonium phosphate has a pH value of 7.8‑8.2 and is weakly alkaline, suitable for acidic soils.

(2) Industrial‑Grade Ammonium Phosphate

When heated, ammonium phosphate decomposes and forms an insulating carbon layer to block combustion, which enables its application in dry‑chemical extinguishing agents. In 1961, the United States developed the "multi‑class dry‑chemical agent", namely the ABC dry‑chemical extinguishing agent. Diammonium phosphate was initially used as the base material, and later replaced by monoammonium phosphate due to its superior anti‑moisture‑absorption performance.

In 1982, the Shanghai Fire Research Institute of the Ministry of Public Security of China successfully developed an ABC dry‑chemical extinguishing agent adopting a mixture of ammonium dihydrogen phosphate and ammonium sulfate as base materials. It also acts as a functional auxiliary for flame‑retardant coatings for steel structures, cables and other scenarios.

(3) Food‑Grade Ammonium Phosphate

In food processing, it is used as an acidity regulator, buffering agent, leavening agent and fermentation buffer.

In flour‑product and baking industries, it improves dough texture and promotes leavening of bread, pastries and other baked goods.

It can be used as a buffering stabilizer in beverages to adjust pH value and maintain product stability, and create a proper acid‑base environment for dairy products and drinks. Its usage shall comply with Chinese National Standard GB 2760‑2024.

Industrial‑Chain and Core Advantages of China's Industry

Upstream core raw materials: phosphate ore, wet‑process phosphoric acid, high‑purity liquid ammonia, purified water, purification & impurity‑removal auxiliaries. China has abundant phosphate‑ore reserves, complete mining and processing systems, as well as world‑leading synthetic‑ammonia production capacity. The raw‑material self‑sufficiency rate reaches 100 %, realizing cost and quality control from the source.

Downstream application sectors: agricultural compound fertilizers, grain‑crop cultivation, fruit‑and‑vegetable planting, industrial flame‑retardant materials, water‑treatment chemicals, food processing, precision electroplating, ceramic manufacturing, new‑energy additives and others.

Safety, Storage and Transportation

Ammonium phosphate is a conventional non‑toxic inorganic chemical raw material. It is non‑flammable and non‑explosive, and is not classified as a hazardous chemical substance. It shall be stored and transported as general chemical cargo with low operational risks. Only product dust may cause mild irritation to the human respiratory tract and eye mucous membranes. Under high‑temperature, high‑humidity and confined conditions, diammonium phosphate will slowly decompose and release trace ammonia gas without major safety hazards.

Storage Specifications

Store in dedicated dry, cool, well‑ventilated and clean chemical warehouses. Packages shall remain fully sealed to isolate humid air, rainwater and water vapor. Keep away from high‑temperature heat sources, open flames and high‑temperature equipment; avoid long‑term high‑temperature stacking to prevent ammonia loss and nutrient degradation of diammonium phosphate. Implement zoned independent stacking. Do not store together with strong acids, strong alkalis or strong oxidizing substances to avoid chemical reactions and material deterioration. Warehouses in high‑humidity regions shall be equipped with ventilation and dehumidification facilities to minimize the risk of product caking.

Transportation Specifications

Comply with general chemical‑cargo transportation specifications. Take full protective measures against rain, moisture, direct sunlight and package damage during transportation to guarantee intact and sealed product packages. Do not transport together with toxic, odorous, strongly corrosive, strong‑acid or strong‑alkali goods to prevent product contamination, deterioration and performance loss. It supports LTL (less‑than‑truck‑load), FTL (full‑truck‑load), sea and land transportation. Export shipments do not require hazardous‑goods filing or hazardous‑goods containers, featuring simpler documentation, lower logistics costs and higher customs‑clearance efficiency.

Safety Protection

For routine operation scenarios, dust‑resistant respirators, safety goggles and labor‑protection gloves provide adequate safety protection. Keep work areas well‑ventilated and reduce dust accumulation and flying dust. In case of skin contact or eye splashes, rinse immediately with large volumes of running water. No major safety hazards such as explosion, poisoning or corrosion exist throughout storage, handling and usage under ambient conditions; the overall operational safety level is high.

Frequently Asked Questions (FAQ)

Q: What core advantages does purchasing Chinese ammonium phosphate have compared with imported supplies?

A:
① Stable supply chain: The complete domestic industrial chain eliminates supply‑disruption risks, and lead‑time for large‑volume orders is controllable.
② Lower costs: Large‑scale mass production and self‑sufficient raw materials avoid import tariffs and ocean‑freight premiums, delivering superior cost‑performance compared with imported products.
③ Flexible customization: Particle size, purity, nutrient indicators and packaging specifications can be adjusted on demand; small‑batch trial orders and long‑term large‑volume framework agreements are supported.
④ Convenient services: Goods can be shipped locally in China for fast after‑sales response. Export logistics formalities are simple with efficient customs clearance.
⑤ Reliable quality: Stable batch‑to‑batch performance and qualified impurity levels; it avoids prominent batch variations and difficult after‑sales claims commonly seen with imported goods.

Q: Does ammonium phosphate bring corrosion risks to equipment?

A: Aqueous solutions of ammonium phosphate are only weakly acidic or weakly alkaline with very low corrosivity. Conventional carbon steel, 304/316 stainless steel, PP, PE and fiberglass‑reinforced plastic are all compatible; special anti‑corrosion reconstruction is unnecessary. Avoid ordinary thin‑walled iron equipment under long‑term high‑concentration operating conditions. It poses no strong‑corrosion risks to copper‑based metals, featuring wide equipment compatibility and low operation‑and‑maintenance costs.

Q: Ammonium phosphate has a relatively high salt‑base level and high Salt Index (SI). What precautions should be taken during application?

A: Both monoammonium phosphate and diammonium phosphate feature relatively high salt‑base level and high Salt Index (SI). For agricultural application, direct contact between seeds, seedlings, root systems and fertilizer shall be strictly avoided to prevent seed burn and seedling scorch induced by excessive local salt concentration. Deep application with soil covering or layered fertilization is recommended. Small‑dose topdressing is preferred at seedling stage. Matching application with urea, potash fertilizers and medium‑ & trace‑element fertilizers can balance nutrients and effectively improve fertilizer utilization rate and crop yields.