SODIUM TRIPOLYPHOSPHATE PRODUCTION PROCESS Russian patent published in 2000 - IPC

FIELD: industrial inorganic synthesis. SUBSTANCE: sodium tripolyphosphate used in surfactant production , in flotation processes, and in oil production industry is prepared from extraction phosphoric acid and soda, process consisting in two-step neutralization of phosphoric acid to molar ratio Na₂O:P₂O₅ = 1.63-1.71. In the first step, 60-70% of soda is added and suspension is filtered to separate phosphate-fluoride sludge, which is then neutralized in presence of seed: first-step phosphate-fluoride sludge taken in amount corresponding to 0.3 to 1.5 wt parts of solid phase per 100 wt parts of the second-step suspension. To filtrate is added conditioning additive, after which filtrate is pulverized into particles of recycle mixture of orthophosphate and/or tripolyphosphate, which are dried and calcined in rotary furnaces at 100 to 450 C and then crushed to yield final product. In total, 3 to 25 wt.pts of phosphate-fluoride sludge as the first-step suspension per 100 wt.pts of the second-step suspension are used. EFFECT: intensified (by 5-15%) neutralization process. 2 cl, 1 tbl, 2 ex