Parameter

Results of Analyses

National Quality Standard

Methods of Analyses

Raw

material

Lab-scale extraction

Scale-up

extraction

(120 kg∙batch⁻¹)

pH H₂O

9.52

12.2

12.7

-

pH meter

Nitrogen (%)

0.02

0.01

0.01

-

Kjehdahl

P₂O₅ HCl 25% (%)

0.53

0.11

0.12

-

Spectrophotometer

K₂O (%)

0.10

0.12

0.22

-

AAS

Sulfur (%)

0.1

0.28

0.22

-

AAS

Total SiO₂ (%)

31.4

10.9

10.1

Min. 10

Gravimetry

Soluble Si (%)

0.008

2.5

1.6

-

Spectrophotometer

Water content

0.37

0.79

1.5

Max. 5

Gravimetry

Organic Carbon

0.49

0.24

0.25

-

Spectrophotometer

MgO (%)

1.96

0.64

0.99

-

AAS

CaO (%)

4.82

1.35

2.14

-

AAS

Al₂O₃ (ppm)

28.16

8.60

8.97

-

AAS

Fe₂O₃ (ppm)

20.91

4.4

7.5

-

AAS

Pb (ppm)

17.1

20.4

32.6

Max. 500

AAS

Cd (ppm)

10.5

0.9

0.8

Max. 100

AAS

As (ppm)

nd*

nd

nd

Max. 100

AAS

Hg (ppm)

Nd

nd

nd

Max. 10

AAS

Cr (ppm)

326.8

nd

6.2

<4%

AAS

Ni (ppm)

40

15.3

19.1

<0.4%

AAS