Yu Zheng-yi
2013
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Journal
Sulphur Phosphorus & Bulk Materials Handling Related Engineering
Abstract
Fluorosilicic acid consists of perfluorosilicic acid nH2F2·SiF4,fluorosilicic acid H2F2·SiF4 and oxygen fluorosilicic acid H2O·SiF4 which is mainly SiF4.Extracted phosphoric acid is not orthophosphoric acid H3PO4,instead,it exists in the forms of fluorophosphoric acid mH2O·nH2F2·(P2O5·kSiF4),and HF and SiF4 can be combined with sulfuric acid to form fluorosulfonic acid.The fact is analyzed that during concentration of extracted phosphoric acid,when the energy concentration of phosphoric acid CE(H3PO4)73.13%,the energy coefficient of SiF4 and P2O5 is close to α(SiF4) and α(P2O5),hence defluorination from fluorophosphoric acid is very difficult,and particularly,it is even more difficult for defluorination from extracted phosphoric acid containing impurities like Fe2O3,Al2O3 and MgO.