Baryte
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Introduction
Natural baryte (barium sulphate, chemical formula BaSO4) can be characterised by:
- High inertness in various media
- High density and, as a result, low oil absorption
- Medium Mohs hardness of 3
- High Refractive Index of 1.64
- Easy wetting
- Easy to disperse (also compared to precipitated barium sulphate)
Natural barium sulphate comes without any residual salts when compared to precipitated grades. In addition, natural barytes are easier to disperse than precipitated grades.
Basic properties
| Portaryte | B | C | D | |
| Property | Value |
Unit | ||
| Moisture | 0.1 | 0.1 | 0.1 | [%] |
| pH | 9 | 9 | 9 | [-] |
| Hardness (Mohs) | 3.5 | 3.5 | 3.5 | [-] |
| Refractive index | 1.64 | 1.64 | 1.64 | [-] |
| Colour (D65/ 10°) L* | 96 | 91.5 | beige | [-] |
| BaSO4 + SrSO4 | 98.5 | 97.5 | 96.5 | [%] |
| SiO2 | 1 | 2 | 3 | [%] |
| Fe2O3 | 0.05 | 0.15 | 0.3 | [%] |
| Density | 4.4 | 4.4 | 4.4 | [kg/ dm3] |
Portaryte is the product name for Sibelco’s natural barytes. Portaryte grades have a low level of (transition) metal impurities (improving thermal stability) and a low silica content. They also exhibit high brightness
Because of its intrinsic high density baryte is often used to increase the weight of an object/article and hereby changing the perception of the quality of the article, especially when made from light-weight plastic material.
Portaryte grades are also used in plastic applications where sound-deadening is desired, e.g in highly filled PP and PE pipes, as well as in many under the hood automotive parts (PP-based engine air intake system).
The relative high refractive index of Portaryte grades also makes them very usefull as opacifiers in certain resin systems, for instance in sunroofs made from PC.
Portaryte grades are also commonly used as cost-effective replacements for precipitated barytes in applications where colour is not critical. Compared to the precipitated grades they are also much easier to wet and to disperse making them more economical as less time and energy is required to make the compound.
Additionally the low oil absorption of Portaryte grades allows for high loading levels in compounds based on a variety of resoin systems
Due to its inertness of baryte, Portaryte grades support good UV and weatherability and chemical resistance compared to conventional fillers.
Barytes are because of their intrinsic high temperature stability also often used in compositions of friction materials (brake-pads).
