Pyrophyllite
Pyrophyllite is a secondary mineral of composition Al2O3 4 SiO2 H2O. In appearance it looks like talc and in physical properties also it is identical to talc but in chemical composition it differs form it. Talc is a hydrous magnesium silicate while pyrophyllite is hydrous aluminum silicate.

Pyrophyllite finds the same use as talc. It is used in insecticide, refractory bricks and industries. It is regarded to have better refractoriness than steatite.

There is no BIS specification for pyrophyllite for its use in any industry. However, specifications quoted by major consuming industries is as follows:

 1.Refractory

Chemical

28% Al2O3 to 31% Al2O3

3 - 4% Alkali

28 to 30% Orton PCE.

The sub-committee on refractory Raw Materials of the DGTD for refractories has stipulated the two grades mentioned below:

Refractory

Grade-I

Grade-II

Al2O3

38% min.

28% min.

SiO2

60% max.

60% max.

Alkalis

1% max.

1% max.

PCE

30% min.

28% min.

 

1. Ceramic Industry:

Physical

Residue below

150 U sieve

- 95%

Chemical

SiO2 64 2%

Al2O3   - 28 2%

Fe2O3   - Less than 1%

TiO2 Less than 0.2%

K NaO Less than 1%

CaO - Less than 0.5%

MgO Less than 0.5%

LOI 4.5 1%

2. Insecticide Industry:

There is no separate specification available for use of pyrophyllite in insecticide industry. However, the specifications for insecticide industry as available for talc/steatite can also be applicable to this, which is as below:

L. O. I.

7% max.

Matter soluble in HCL

3% max.

Fe2O3

1.5 max.

Pyrophyllite has not been included in the list of minerals for the preparation of mineral inventory. However, the known reserves are not at present classified according to the end use.

Industry:

1.

Refractory

Al2O3

SiO2    

Alkalies

PCE (Orton cone.)

28% min.

60% max.

1% max.

28% min.

2.

Ceramic

Al2O3

SiO2    

Fe2O3  

TiO2    

CaO

MgO

28 2%

64 2%

Less than 1%

Less than 0.2%

Less than 0.5%

Less than 0.5%

3.

Insecticide       

L. O. I.

Matter soluble in HCL

Fe2O3  

7% max.

3% max.

1.5% max.

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