LÜ Li, LIANG Bin, LIU Qiang, et al. Reactions between P2O5 and calcium phosphate in kiln phosphoric acid[J]. CIESC Journal, 2016, 67(10): 4399-4405. DOI: 10.11949/j.issn.0438-1157.20160688.
LÜ Li, LIANG Bin, LIU Qiang, et al. Reactions between P2O5 and calcium phosphate in kiln phosphoric acid[J]. CIESC Journal, 2016, 67(10): 4399-4405. DOI: 10.11949/j.issn.0438-1157.20160688.DOI:
Side reactions of gaseous product P2O5 with phosphate ores (so-called P2O5 back absorption) in rotary kiln produce large quantities of low melting point solid products
which could form a kiln ring
block material flow and cause unstable operation of the kiln. The back absorption of gaseous P2O5 with calcium phosphate was studied at different temperatures and the products were characterized for P2O5 content
morphology
phase composition
structure and thermal stability by chemical analysis and other techniques of SEM
XRD
IR
Raman
TG and DSC. The experimental results show that temperature significantly affected the back absorption
which was occurred above 500℃. Calcium metaphosphate was formed at 500-900℃ with almost pure calcium metaphosphate at 900℃. Calcium metaphosphate decomposed into calcium pyrophosphate and P2O5 at 1000-1300℃ with almost pure calcium pyrophosphate at 1300℃.