The main feature of WPA production dihydrate method is decomposition of phosphate raw materials with a mixture of sulphuric and phosphoric acids with calcium sulphate crystallization in the form of a stable phase - CaSO4*2H2O dihydrate. Standard DH process flowsheet is shown in Figure 1.
Figure 1. DH process flowsheet
Plant unit production capacity is up to 300 thousand tons of Р2О5 per year or more.
General advantages of the DH process:
Main disadvantages of DH process:
JSC NIUIF developed high efficiency dihydrate process, which allows to significantly improve efficiency and increase the content of Р2О5 in WPA from filtration unit.
The improvement of the DH process for phosphate raw materials - Khibiny apatite concentrate is:
Increasing Р2О5 content in WPA can significantly reduce the energy consumption for its concentration. The average process yield of Р2О5 in the improved process reaches 97.5÷97.7%. The implementation of the process is relevant for new plants with a unit capacity of about 300 thousand tons of Р2О5 per year, the modernization of operating plants is also possible.
Main parameters of JSC NIUIF high efficiency dihydrate process
Parameter |
Apatite concentrate KOLA |
Karatau Phosphate rock |
Plant production capacity, thousand tons of Р2О5 per year |
300÷450* |
up to 220 |
Reaction volume, m3 |
1200÷3200* |
1100 |
Total filtration surface, m2 |
250÷390* |
250 |
Р2О5 content in WPA from filtration unit, % |
30÷33 |
25÷27 |
*for modernization of operating plants