Vermiculite specification

Specification Details


Grades

Crude Vermiculite from the mine consists of golden to brown flakes which are carefully classified into five grades - each with a specified range of particle sizes, as detailed in the table below:

Grade Particle size distribution min. 80% retained (mm) Loose bulk Density kg/m3
LARGE -8.0 + 2.8 700 - 850
MEDIUM -4.0 + 1.4 800 - 950
FINE -2.0 + 0.710 850 - 1050
SUPERFINE -1.0 + 0.355 850 - 1050
MICRON -0.710 + 0.250 850 - 1050
* The above specified values may vary to the actual values

Exfoliated Vermiculite

Vermiculite is most widely used in its exfoliated form. The concertina-shaped granules of exfoliated vermiculite are non-combustible as well as being insoluble in water and all organic solvents. Safe and easy to handle, exfoliated vermiculite is available in the market place in five different grades as shown in the table below:

Volume Yields for Exfoliated Vermiculite

Grade Typical loose bulk densities of product(kg/m3) Typical volume yields per ton of crude vermiculite processed (m3)
MICRON 105 - 135 7.5 - 9.0
SUPERFINE 85 - 100 8.5 - 10.0
FINE 75 - 85 10.5 - 11.5
MEDIUM 70 - 85 11.5 - 13.0
LARGE 60 - 75 13.0 - 14.5
* The above specified values may vary to the actual values

The above values are those obtained by commercial operation and these values may vary for different designs of exfoliate.

pH Value:7.5 - 9.0
Thermal Conductivity:0.063 - 0.069 W/mºC under ambient conditions
Specific Surface Area:The specific surface area for exfoliated vermiculite, as measured by the nitrogen absorption technique, is typically:
Specific Surface Area m2/g
Micron 6.4
Superfine 5.4
Fine 4.4
Medium 4.0

Chemical Analysis

The chemical analysis of both crude and exfoliated vermiculite is the same

Typical Ranges for Major Components
SiO2 35 - 41%
Al2O3 6.0 - 10.0%
Fe2O3 6.0 - 9.5%
MgO 21.5 - 25.5%
K2O 3.0 - 6.0%
Typical Ranges for Minor Components
CaO 2.0 - 6.0%
CO2 0.6 - 2.5%
TiO2 0.6 - 1.4%
F 0.2 - 0.8%
Cr2O3 0.01 - 0.10%
P 0.2 - 2.0%
Cl 0 - 0.5%
Angle of Repose:38º to 26º according to grade
Specific Heat:1.03 kJ.K. at 20ºC 1.05kJ/kg.K. at 30ºC
Specific Gravity:2.5 to 2.6 depending on the grade
Mohs Hardness:Between 1 & 2
pH Value :8.5 to 10
Weight Loss: At 105ºC - 4.5 to 6.5%. At 95ºC - 8.0 - 10.0%

 

 

 
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