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Boron nitride - also called white graphite - is considered to be the world’s second-hardest material after diamonds. It is not found in nature and is therefore produced synthetically. Compared to diamonds, boron nitride has the advantage of being much more heat resistant and suffering little loss of hardness even at 1000°C.
For the production of this material, which is mostly used as grinding medium, AVA has once again found an innovative technological solution: A vertical reactor with a gross volume of 1000 litres working at a temperature up to 700°C, the vessel at full red heat. This temperature can be reached and held only with special steels, ceramic heating elements and very special insulation. Inside the reactor a Mitrava helix with particular design moves the product mixture up along the heated vessel wall, where it flows down in the centre along the shaft, first as a powder, then as a molten mass and finally as the solid end product.
Feeding and discharge valves must be designed for extreme temperatures, as well as all connections, bearings and seals. For monitoring the filling level the mixing reactor was built on load cells. Once again a piece of “more than just mixing” from the AVA technology think tank!
If you want to learn more about innovations and trends in mixing and drying technology please visit the AVA booth no. 314, Hall 9 at the Powtech in Nuremberg
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