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How to make phosphoric acid and its properties

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How to make phosphoric acid and its properties

phosphoric acid is an important inorganic acid with a chemical formula of Hover PO, which is widely used in chemical, agricultural, food processing, pharmaceutical and electronic industries. In this paper, the manufacturing method and characteristics of phosphoric acid will be discussed in detail, and its application value in industry will be analyzed.

1. Manufacturing method of phosphoric acid

the production of phosphoric acid mainly relies on phosphate ore (the main component is CaⅨ F (POⅨ)), which is extracted by a chemical process. The following are the main manufacturing methods of phosphoric acid:

1.1 wet process

the wet process is the main method of producing phosphoric acid at present, which is suitable for the treatment of high-grade phosphate rock. The process includes the following steps:

  • ore crushing and grinding: Crushing and grinding the phosphate rock into fine particles to increase the reaction surface area.
  • acidification reaction: The ground ore is reacted with sulfuric acid (H₂ SOO₂) at high temperature to produce calcium phosphate and calcium sulfate. The reaction equation is: [ Ca₅F(PO₄)₃ H₂SO₄ → 5CaSO₄ H₃PO₄ HF ]
  • filtration and purification after the reaction, insoluble impurities and calcium sulfate were removed by filtration to obtain a phosphoric acid solution.
  • concentration and crystallization the phosphoric acid solution is concentrated and crystallized by cooling or evaporation to obtain phosphoric acid solid.

1.2 thermal process

the thermal process is suitable for the treatment of low-grade phosphate rock, which is converted into phosphate by high-temperature calcination and then reacted with acid to produce phosphoric acid. The specific steps are as follows:

  • calcination: Phosphate ore is mixed with coke or coal and calcined at high temperature to produce phosphorus oxides (such as Ca1 (PO4)).
  • acidification reaction: The calcined product reacts with sulfuric acid to produce phosphoric acid.
  • filtration and purification: High-purity phosphoric acid is obtained through steps such as filtration and distillation.

2. Characteristics of phosphoric acid

as a strong acid, phosphoric acid has the following physical and chemical properties:

2.1 physical characteristics

  • appearance: Colorless or yellowish liquid, highly corrosive.
  • Density: about 1.80g/cm³ (pure phosphoric acid).
  • Melting Point: about 47°C.
  • Boiling Point: about 158°C (at atmospheric pressure).

2.2 chemical characteristics

  • acidic phosphoric acid is a medium and strong acid that can react with alkaline substances (such as metal oxides, hydroxides) to generate the corresponding salts and water.
  • complexation phosphoric acid has a certain complexation effect and can form complexes with metal ions.
  • Hydrolysis phosphoric acid is partially ionized in water to generate H, H, PO, and PO ions.

2.3 Application Features

  • buffer phosphoric acid and its salts have good buffering properties and are widely used in the pharmaceutical and food industries.
  • Corrosion phosphoric acid is highly corrosive to metal and non-metal materials and needs to be stored and transported with acid-resistant materials.

3. Application fields of phosphoric acid

phosphoric acid has important applications in many fields, including:

3.1 chemical industry

  • phosphate production phosphoric acid reacts with alkali to produce phosphates, such as diammonium phosphate (DAP) and diammonium phosphate (MAP), which are widely used in fertilizer production.
  • surface active agent phosphate ester compounds are used as surfactants in detergents and cosmetics.

3.2 agricultural field

  • fertilizer production phosphoric acid is the main raw material for the production of phosphate fertilizer, which can promote plant growth and enhance crop disease resistance.
  • soil improvement phosphoric acid can be used to improve acidic soil and adjust soil pH.

3.3 food processing

  • food Additives phosphoric acid is used as a food acidity regulator, stabilizer and preservative.
  • Beverage production phosphoric acid is an important component of carbonated drinks such as cola.

3.4 pharmaceutical industry

  • pharmaceutical intermediates phosphoric acid is used in the production of pharmaceutical intermediates such as antibiotics, vitamins and anticoagulants.
  • buffer system phosphate buffer is used in pharmaceutical preparations and biotechnology research.

4. Environmental issues in the manufacture of phosphoric acid

contaminants such as fluoride, sulphate and phosphogypsum (a by-product) may be produced during the production of phosphoric acid. In order to reduce the impact on the environment, modern phosphoric acid production adopts the following environmental protection measures:

  • exhaust gas treatment: Reduction of fluoride and sulfur dioxide emissions through dust removal and desulfurization technologies.
  • wastewater treatment: Neutralization and precipitation processes are used to treat phosphorus-containing wastewater to reduce water pollution.
  • phosphogypsum utilization: Use phosphogypsum as a building material (such as cement additive) or soil conditioner to realize resource utilization.

5. Conclusion

as an important industrial raw material, the manufacturing process and application characteristics of phosphoric acid have a profound impact on many industries. Through wet and thermal processes, phosphoric acid can be produced efficiently and meet the needs of different fields. The process of phosphoric acid production also faces environmental challenges, which requires technological innovation and resource optimization to achieve green production.

Phosphoric acid has broad application prospects in industry, agriculture and medicine, but its production and application still need to pay attention to environmental protection and sustainable development. In the future, with the advancement of technology, the manufacture and application of phosphoric acid will be more efficient and environmentally friendly.

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