Cleaning of Extracted Phosphoric Acid

Abstract

Introduction: World production of extraction phosphoric acid (EPA) amounted to 48.9 million tons of P₂O₅ in 2015 and is projected to increase by 7.7 million tons of P₂O₅ by 2020. The widespread development of the production of purified phosphoric acid (PPA) compared to thermal acid (TPA) is facilitated by lower energy costs (up to 200 kWh per 1 ton of P₂O₅ versus 7500 kWh per 1 ton of P₂O₅), high manufacturability and the possibility of producing phosphoric acid of any quality (technical, food, pharmaceutical, reactive). In this regard, they predict an annual growth of OFK production by 3.3% per year, further improvement, and development of its production.

Objectives: purification of extractive phosphoric acid from additives and obtaining a suspended complex fertilizer.

Methods: Extraction phosphoric acid is in contact with an organic solvent, which is partially or completely immiscible with aqueous. After settling, two phases are separated: the aqueous phase (raffinate) and the organic phase, which contains a significant amount of H₃PO₄ and a small amount of impurities.

Results: The results of the study of the FA extraction process with 100% MEA, DEA and TEA are presented in Table 2. A characteristic feature of the FA extraction process with MEA, DEA and TEA is the increase in Kd with increasing FA concentration, which is associated with a change in the composition of the extracted complex, which is a combination of molecules FA, water and extractant [3]. It should be noted that the Kd value remains almost constant, about 0.30. During the experiment, at most points the ratio of the volumes of the organic and aqueous phases was equal to 1, while the degree of extraction (φ) was in the range of 25-30%..

Conclusions: Thus, the removal of primary silicon nuclei from the EPA solution is ensured by the movement of sediment particles into organic matter and thereby reducing their concentration in the volume of the solution. The EPA solution sequentially transforms into a single-phase system that does not contain primary sediment particles, which, in turn, are the result of the interaction of complexing ions that prevent the binding of HF into complex compounds, especially into aqua complexes. Along with this, the formation of complex compounds of iron and aluminum is possible in the amorphous phase.