Vermiculite specifications

Safety Data sheet

Technical Specification: Crude & Exfoliated Vermiculite

Crude vermiculite from the Palabora mine consists of golden/brown flakes which are carefully classified into different grades – each with a specified range of particle sizes, as detailed in the table below. 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. Completely safe and easy to handle, exfoliated vermiculite is available in different grades.

Palabora Vermiculite: Typical Specification
Vermiculite		Crude Vermiculite		Exfoliated Vermiculite
No	Grade	(1) Size (mm)	(2) Density (kg/m³)	(3) Yield (m³)	(4) Density (kg/m³)
4	Large	- 8.0 + 2.8	700 - 850	12.0 - 14.5	60 - 75
3	Medium	- 4.0 + 1.4	800 - 950	10.0 - 13.0	70 - 85
2	Fine	- 2.0 + 0.71	850 - 1050	8.0 - 11.5	75 - 85
1	Superfine	- 1.0 + 0.355	850 - 1050	7.0 - 10.0	85 - 100
0	Micron	- 0.71 + 0.25	850 - 1050	6.0 - 9.0	105 - 135
	Supermicro	1.0 + 0.25	850 - 1050	6.2 - 9.0	90 - 135
	RSU	- 0.5 + 0.18	850 - 1050	3.0 - 5.0	115 - 150
	DDM	- 0.1 + 0.0	1250 - 1550	2.0 - 2.5	350 - 400
Notes: (1) Particle size distribution minimum 80% retained (mm). (2) Loose bulk density of product (kg/m³). (3) Typical volume yields (cubic metres of exfoliated vermiculite) per tonne of crude vermiculite processed (m³). (4) Typical loose bulk density of product (kg/m³). The typical loose bulk densities and volume yields for exfoliated vermiculite produced in the table above are values obtained by commercial operation of an S.S.T. Rotary Exfoliator. These values may vary slightly depending on the type of furnace used, the efficiency of the production system and on the feed rate of the crude vermiculite into the furnace.

Chemical Analysis: Crude & Exfoliated Vermiculite

When analysed chemically, crude and exfoliated vermiculite give the same values. Because vermiculite is a naturally occurring substance its exact composition may vary from sample to sample.

Typical Ranges for Major Components
SiO₂	Silicon Dioxide	35 - 41%
Al₂O₃	Aluminium Oxide	6.0 - 9.5%
Fe₂O₃	Iron Oxide	6.0 - 9.5%
MgO	Magnesium Oxide	21.5 - 25.5%
K₂O	Potassium Oxide	3 - 6%

Typical Ranges for Minor Components
CaO	Calcium Oxide	2.0 - 6.0%
CO₂	Carbon Dioxide	0.6 - 2.5%
TiO₂	Titanium Dioxide	0.6 - 1.4%
F	Fluorine	0.2 - 0.8%
Cr₂O₃	Chrome Oxide	0.01 - 0.15%
P₂O₅	Phosphorus Pentoxide	0.2 - 2.0%
Cl	Chlorine	0 - 0.5%

Specific Surface Area: Exfoliated Vermiculite

The specific surface area for exfoliated vermiculite, as measured by the nitrogen absorption technique, is typically:

Exfoliated vermiculite
No	Grade	M²/g	No	Name	M²/g>
4	Large	3.4		Supermicro	6.0 *
3	Medium	4.0		RSU	7.2
2	Fine	4.4		DDM	7.5
1	Superfine	5.4
0	Micron	6.4

* Not determined by nitrogen absorption but calculated from Superfine and Micron values.

Absorption Capacity: Exfoliated Vermiculite

All grades of exfoliated vermiculite will retain liquids within the inter-laminar voids of the individual particles as well as between the particles themselves.

This table gives an indication of the quantity of liquid which can be retained using Superfine grade vermiculite before drainage of the liquid occurs.

Liquid	Volume of Liquid Absorbed in 1 Litre of Vermiculite (ml)
Liquid	DDM	RSU	Micron	Superfine	Fine	Medium	Large
Water			517	457	406	310	280
Diesel Oil			454	335	273	213	183
Heavy Gear Oil			488	411	353	268	174
15/40 Multigrade Oil			543	356	350	262	193
Note: (a) Diesel oil used in the test is 35 second gas oil, which is very similar to paraffin. (b) 15/40 Multigrade oil is oil that meets certain low-temperature and high-temperature requirements simultaneously and is commonly used as engine oil. (c) Absorption is related to surface area of the particle and the finer grades have, on a volume basis, more surface area than the coarser grades (i.e. Large Grade).

Other supporting technical data: Crude Vermiculite

Angle of Repose	This varies from 38º to 26º according to grade
Melting Point	Collapse and coalescence of the individual flakes begins at 1330ºC
Specific Heat	1.03 kJ/kg.K. at 20ºC 1.05 kJ/kg.K. at 30ºC
Specific Gravity	2.5 to 2.6 depending on grade
Mohs Hardness	Between 1 & 2
pH Value	Crude Vermiculite: 8.5 to 10
Weight Loss	At 105ºC - 4.5 to 6.5% At 950ºC - 8.0 to 10.0% Note: (a) At the lower temperature all the weight loss will be water. (b) At the higher temperature most of the weight loss will be water but some will be volatile components such as carbon dioxide.
Aspect Ratio: Ratio of flake diameter to flake thickness	As received, this varies from 7:1 to 30:1 depending on grade. Mechanical processing can produce aspect ratios of 50:1. Chemical and mechanical processing can produce ratios of 200:1. Note: The higher the aspect ratio the thinner the vermiculite flake.
Cation Exchange	The exchangeable cation normally present in vermiculite is Magnesium. The cation exchange capacity of Palabora Vermiculite is up to 600 milliequivalents per kg. The rate of cation exchange will depend on exposed surface area; therefore, the best results are obtained using exfoliated vermiculite.

Disclaimer: The details contained in this document are provided as a source of information and for guidance only. Whilst every effort is made to ensure the content is accurate and up to date, use of the information contained in this document is solely at the discretion, risk and liability of the recipients.

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