Phosphorus pentoxide from Kazakhstan phosphorus as a base for production of polyphosphoric acids (PPA) in the cascade reactors system

The polyphosphoric acids (PPA) were synthesized in a cascade reactors system from P₂O₅ obtained from the burning of Kazakh phosphorus. Presented system provides guidelines for the PPA production process using phosphoric acids only at concentrations above 100% (in conversion to H₃PO₄). Polyphosphoric acids are processed in a cascade reactors system, where the in 1^st concentration of PPA is increased by addition of P2O₅, while in the 2^nd reactor PPA is diluted with the use of 85% phosphoric acid. Produced PPA can be obtained in the 100–118% range and is characterized by high chemical purity due to the reduction of the corrosivity of the reaction, which results in very low content of iron (below 2 ppm Fe).