| ≥1 piece |
|
index
|
Wonderful grade
|
First grade
|
Up to grade
|
|
purity% ≥
|
99.6
|
99.4
|
99.0
|
|
suiphate group % ≤
|
0.08
|
0.10
|
0.20
|
|
ignition (850 o C) % ≤
|
0.08
|
0.10
|
0.20
|
|
heavy metal % ≤
|
0.001
|
0.002
|
0.02
|
|
Iron content % ≤
|
0.0012
|
0.002
|
0.01
|
|
chlorides % ≤
|
0.003
|
0.004
|
0.01
|
|
calcium % ≤
|
0.0012
|
/
|
/
|