Item

Index

Type I

Type Ⅱ

Type Ⅲ

Premium product

First-class product

First-class product

Qualified product

First-class product

Qualified product

appearance

White crystalline particles

Na2SO4）/w/% ≥

99.6

99.0

98.0

97.0

95.0

92.0

water-insoluble substance
/w/% ≤

0.005

0.05

0.10

0.20

—

—

Total content of calcium and magnesium（Mg）/w/% ≤

—

0.15

0.30

0.40

0.6

—

Ca
/w/% ≤

0.01

—

—

—

—

—

Mg
/w/% ≤

0.01

—

—

—

—

—

Cl
/w/% ≤

0.05

0.35

0.70

0.90

2.0

—

Fe
/w/% ≤

0.0005

0.002

0.010

0.040

—

—

moisture content
/w/% ≤

0.05

0.20

0.5

1.0

1.5

—

Whiteness（R457）
%/ ≥

88

82

82

—

—

—

pH(50g/L aqueous solution，25℃)

6-8

—

—

—

—