Phosphoric Acid → Phosphorus oxide (P4O10)

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Reaction Steps

In the conventional methods for the production of wet process phosphoric acid, finely ground phosphate rock is reacted with dilute phosphoric acid (10% P2O5 to 25% P2O5) and sulphuric acid which may or may not be diluted. The reaction product is leached (i.e., digested or reacted with the acid) to yield a crude aqueous phosphoric acid solution in which is suspended a substantial quantity of solid impurities. This slurry is filtered to separate most of the undissolved calcium sulfate and other solid impurities to yield a crude (22% P2O5 to 45% P2O5) aqueous product sometimes known as the number one filtrate. This filtrate contains suspended, finely divided, impurities that were not removed during the solid-liquid separation step plus solids that have crystallized after filtration. The solution also contains dissolved impurities. Reference is made to Chapter 16 of Volume II, Phosphorus and its Compounds, Van Wazer, Interscience Publishers (1961).

Provenance & Evidence