Table 2 Saturation index (SI) values simulated at the final concentration factor (CF) obtained in MAC tests performed at different temperatures for real mine tailings wastewater before (Real) and after (BT) basic treatment (numbers in bold refer to the species that were actually detected in the solid precipitate by PXRD analysis)

Huntite

CaMg₃(CO₃)₄

5.39

9.99

6.00

10.78

6.38

11.64

Gorgeyite

K₂Ca₅(SO₄)₆·H₂O

5.13

3.52

4.25

2.66

5.36

5.21

Dolomite

CaMg(CO₃)₂

3.53

5.55

3.73

5.84

3.85

6.14

Magnesite

MgCO₃

1.63

2.92

1.57

2.90

1.60

3.08

Calcite

CaCO₃

0.97

1.71

1.03

1.82

1.04

1.85

Aragonite

CaCO₃

0.77

1.51

0.80

1.58

0.79

1.60

Gypsum

CaSO₄·2H₂O

0.41

−0.04

0.34

−0.10

0.52

0.26

Anhydrite

CaSO₄

0.38

−0.05

0.46

0.03

0.74

0.57

Halite

NaCl

−0.15

−0.08

−0.17

−0.10

0.05

0.37

Nesquehonite

MgCO₃·3H₂O

–

−0.16

–

−0.22

–

−0.24

Glauberite

Na₂Ca(SO₄)₂

−0.39

−0.45

−0.36

−0.40

0.17

0.69

Sylvite

KCl

−0.64

−0.47

−0.74

−0.58

−0.61

−0.26

Nahcolite

NaHCO₃

–

−0.76

–

−0.72

–

−0.43

Thenardite

Na₂SO₄

–

−1.14

–

−1.09

–

−0.53

Polyhalite

K₂MgCa₂(SO₄)₄·2H₂O

−1.18

−1.38

−1.53

−1.70

−0.74

0.09

Artinite

Mg₂CO₃(OH)₂·3H₂O

−1.49

−0.29

−0.88

0.41

−0.98

0.21

Arcanite

K₂SO₄

–

−1.72

–

−1.84

–

−1.58

Hexadryte

MgSO₄·6H₂O

–

−1.77

–

−1.85

–

−1.55

Pentahydrite

MgSO₄·5H₂O

−2.02

−1.94

−2.15

−2.06

−2.00

−1.71

Kieserite

MgSO₄·H₂O

−2.43

−2.33

−2.31

−2.19

−1.94

−1.48

Kainite

KMgClSO₄·3H₂O

−2.54

−2.28

−2.66

−2.40

−2.29

−1.57

Bloedite

Na₂Mg(SO₄)₂·4H₂O

−2.69

−2.08

−2.84

−2.36

−2.42

−1.40