Table 5 2FI model terms and significance.

From: Investigation on process optimization and kinetics for leaching of rare earth elements from red mud using citric acid

Source

Sum of Squares

Degree of freedom

Mean square

F-Value

P-Value

Remarks

Model

357.42

6

59.57

102.92

< 0.0001

Significant

A-Leachant Concentration

224.48

1

224.48

387.85

< 0.0001

 

B-Temperature

95.58

1

95.58

165.15

< 0.0001

 

C-Time

24.93

1

24.93

43.08

< 0.0001

 

AB

2.72

1

02.72

4.70

0.0492

 

AC

5.11

1

05.11

8.83

0.0108

 

BC

4.59

1

04.59

7.94

0.0145

 

Residual

7.52

13

0.579

   

Lack of Fit

6.03

8

0.753

2.52

0.1625

Not significant

Pure Error

1.50

5

0.299

   

Correlation Total

364.95

19