Experiment
No.

t (min), A
30,45, 60

Slurry (%), B
5, 10, 15

Molar ratio, C
 (moles Na2CO3/ moles gypsum)
0.8, 1.4, 2

v(rpm) D
100,300;500

Phospho- gypsum Conversion
(%)

1

0

5

0.80

100

7

2

120

5

0.80

100

54

3

0

15

0.80

100

2.61

4

120

15

0.80

100

52

5

0

5

2

100

12.60

6

120

5

2

100

86

7

0

15

2

100

2.40

8

120

15

2

100

37

9

0

5

0.80

500

11

10

120

5

0.80

500

72

11

0

15

0.80

500

4.43

12

120

15

0.80

500

58

13

0

5

2

500

4.8

14

120

5

2

500

97

15

0

15

2

500

5.60

16

120

15

2

500

61.71

17

0

10

1.40

300

4.32

18

120

10

1.40

300

58.81

19

60

5

1.40

300

69

20

60

15

1.40

300

51

21

60

10

0.80

300

53

22

60

10

2

300

62

23

60

10

1.40

100

42

24

60

10

1.40

500

83

25

60

10

1.40

300

58.21

26

60

10

1.40

300

57.91

27

60

10

1.40

300

59.61

Table 4: Experimental results for treatment of Foskor phosphogypsum with Sodium Carbonate using central composite design.