MOH'S HARDNESS SCALE

 

   One of the major factors which governs the choice and design of size reduction machines, air classifiers, mixers and dryers, etc. is the hardness of the material to be processed.

 

  As general rule, the hardness is defined in accordance with Moh's scale of hardness, which divided into 10 grades of hardness.

 

          Hardness 1 -3 = soft

          Hardness 3.5 -5 = medium hard

          Hardness 5 -10 = hard

 

HARDNESS

MATERIAL

1

1

1-2

1-2

1-2

2

2

2

2.5

3

3

3

4

4

4-5

4-5

5

6

6

6-7

7

7

8

8.5

8.5

9

9

9.5

9-9.7

9.7

10

Talcum

Graphite

Boron nitride (BN)

Coloured clay

Gypsum

Whetstone

Rock salt

Sulphur

Mica

Calcite

Chalk

Marble

Barites

Dolomite

Magnesite

Ironspar

Apatite

Feldspar

Magnetite

Rutile

Quartz

Pyrite

Basalt

Tungsten carbide

Zircon Oxide

Corundum

Silicon nitride

Borium carbide

Silicon carbide

Borium nitride,cubic

Diamond

 

 =============================================

Analysis Sieve Comparison Table

ISO 565

1987

DIN 4188

1977

US Std/ASTM

E-11-1987

Tyler®

BS 410

1986

mm

mm

US Mesh

Mesh

Equivalent BS Mesh

 

 

Inch

Inch

 

 

 

3" .

 

 

 

 

2".

 

 

26,5

25

1.06"

1.05".

 

25

22,4

1"

 

 

22,4

20

7/8"

0.883"

 

19

18

3/4"

0.742"

 

16

16

5/8"

0.624"

 

13,2

14

0.530"

 

 

12,5

12,5

1/2 "

 

 

11,2

11,2

7/16"

0.441"

 

9,5

10

3/8"

0.371"

 

 

9

 

 

 

 

 

 

Mesh

 

8

8

5/16"

2.5

 

6,7

7,1

0.265"

3

 

6,3

6,3

1/4"

 

 

 

 

Mesh

 

 

5,6

5,6

3.5

3

4,75

5

4

 

 

4,5

 

 

 

4

4

5

5

4

3,35

3,55

6

 

5

 

3,15

 

 

 

2,8

2,8

7

 

6

2,36

2,5

8

8

7

 

2,24

 

 

 

2

2

10

 

8

1,7

1,8

12

10

10

 

1,6

 

 

 

1,4

1,4

14

12

12

1,18

1,25

16

14

14

 

1,12

 

 

 

1

1,0

18

16

16

Microns (µm)

Microns (µm)

 

 

 

850

900

 

 

18

 

800

20

20

 

710

710

25

24

22

 

630

 

 

 

600

 

30

28

25

 

560

 

 

 

500

500

35

32

30

 

450

 

 

 

425

430

40

35

36

 

400

 

 

 

355

355

45

42

44

 

315

 

 

 

300

 

50

48

52

 

280

 

 

 

250

250

60

60

60

212

224

70

65

72

 

200

 

 

 

180

180

80

80

85

 

160

 

 

 

150

 

100

 

100

 

140

 

 

 

125

125

120

115

120

106

112

140

150

150

 

100

 

 

 

90

90

170

170

170

 

80

 

 

 

75

 

200

200

200

 

71

 

 

 

63

63

230

250

240

53

56

270

270

300

 

50

 

 

 

45

45

325

325

350

38

40

400

400

400

 

36

 

 

 

32

32

450

450

440

25

25

500

500

 

20

20

635

635

 

16

16

 

 

 

10

10