DEProduction of aluminium oxide powder
Mixer and agitators
After oxygen and silicon, aluminium, coming in at around 7.5 %, is the third most common element in the earth’s crust. It is extracted from natural deposits of bauxite in a series of laborious processes. Aluminium’s versatility makes it indispensable in almost all areas of life and manufacturing. In the Bayer method, the bauxite is first mixed with caustic soda, processed in an autoclave and then dehydrated into a fine white powder, aluminium oxide (Al2O3), in a calcinating kiln. In this process approx. two tons of aluminium oxide are obtained from four tons of bauxite.
Continuous measurement with VEGAPULS 62 in the digester and in the decanter
The bauxite is decomposed by adding thinned caustic soda and mixing it throroughly with the bauxite in the digester. To achieve an optimal utilisation of the process, it is important to regulate the filling level in a fixed range. Contactless radar technology has all the right prerequisites for this measurement task. The VEGAPULS 62 radar sensor records the current level and passes it on to the control system. Even the rotating agitator blades do not disrupt the measurement. Also in the decanter, which immediately follows the digester, VEGAPULS 62 reliably performs its service in temperatures up to 200 °C (473 °F) and pressures up to 40 bar (580 psig). The steam atmosphere prevailing in the vessel does not affect the measurement either.