Colemanite

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Introduction:
Colemanite is a borate mineral with the chemical formula Ca2B6O11·5H2O and is the main ore for Boron production.
Thermal decomposition at 330 °C, loosing its water of hydration according to the following reaction:
Ca2B6O11·5H2O -> Ca2B6O11 + 5H2O
The Ca2B6O11 char residue has better mechanical properties than MgO, the char residue coming from the thermal decompostion of hydromagnesite.
Further characterized by:
- Relatively low density of 2.42 g/cm3 compared to other mineral fillers, which are typically at 2.7 g/cm3
- Medium Mohs Hardness of 4.0
- Decomposition around 330°C, releasing water.
Basic properties
Property | Value | Unit |
Hardness (Mohs) | 4.0 | [-] |
Refractive index | 1.61 | [-] |
Density | 2.42 | [kg/ dm3] |
PORTAFLAME® CA, C grades are micronized halogen-free flame retardant (HFFR) fillers (based on Colemanite), used as an effective synergist for other flame retardant fillers, such as ATH and magnesium hydroxide.
Setting PORTAFLAME® CA, C grades apart from other flame retardant minerals is that the flame-retarding mechanism of PORTAFLAME® CA, C is based mainly upon its high char forming and glazing/fluxing ability in combination with endothermic decomposition (heat-sink effect). In applications such as polyolefin-based Wire & Cable compounds, a significant reduction of the peak Rate of Heat Release, as measured by the oxygen depletion method, is achieved.
PORTAFLAME® CA, C grades are easy to process and are an economical alternative to other flame-retardant fillers.