DH-HH Process

The process was developed by JSC NIUIF and is protected by RF patents.

Technology advantages:

  • implementation of a two-stage process for WPA production from various types of phosphate raw materials: Khibiny apatite concentrate and Karatau phosphate rock (Koksu deposit);
  • conducting d/h stage in high-temperature high efficiency process mode, which reduces the required reaction volume, increases the degree of Р2О5 extraction in WPA and eliminates steam injection at the recrystallization stage;
  • increase of the Р2О5 content in the production of weak WPA by 3÷6% relative to a single-stage DH process;
  • reduction of flow rate coefficients for phosphate raw materials and sulphuric acid (due to Р2О5 analytical yield increase) and steam flow rate for concentration of weak WPA by 20%;
  • possibility of implementing the process with full or partial processing of the obtained alpha-hemihydrate of calcium sulfate;
  • obtaining higher quality gypsum raw materials with the lowest possible content of Р2О5 and F impurities;
  • obtaining high-quality gypsum binder directly on the basis of alpha-hemihydrate after drying, regrinding and additives injection (if necessary).

DH-HH process flowsheet for WPA production from Khibiny apatite concentrate is shown in Figure 1.

DH-HH process eng.jpg

Main parameters of JSC NIUIF DH-HH process:

Parameter

Apatite concentrate KOLA

Phosphate rock Karatau (Koksu)

Plant production capacity, thousand tons of Р2О5 per year

180

up to 220

Reaction volume, m3

DH stage

HH stage

 

650

180

 

1100

50

Amount of DH slurry for recrystallization, %

20÷25

10÷15

Total filtration surface, m2

DH stage

HH stage

 

80

60

 

250

20

Р2О5 content in WPA from filtration unit, %

32÷33

30÷31

Р2O5 process yield, %

98,8÷99,2

98,0

Amount of commercial gypsum, thousand tons per year

~700

~150

Content of impurities* in commercial gypsum, % by mass: 

Р2О5total 

Р2О5water 

F

     


0,25÷0,30 (≤0,5)

≤0,1(≤0,2)

≤0,1(≤0,2)

 


 ≤0,30

≤0,1

≤0,1

* - in brackets you can see the data on the quality of gypsum obtained from Khibiny apatite concentrate on DH-HH plant (Central Prayon process is the closest industrial analogue).