Casting compounds

are usually produced on the basis of Al2O3 or MgO. Depending on the applica- tion, approx. 5 – 11% water is also added. The compaction is carried out in vibra- tion vessels, which are available in the trade with diameters of approx. 15 to 60 mm. The lower the water content during processing, the denser the compound becomes. The drying of the compounds must take place very carefully and very slowly. The recommended temperature increase should be 30 °C/h, followed by a standing time of 30 minutes on reaching 500 °C, which is repeated at every fur- ther 100 K while increasing the temperature again by 50 °C/h. The compounds must be heated up to at least 1,000 °C, followed by a standing time of 2 hours. High-performance burners using oxygen reach temperatures of approx. 1,200 °C, in which case a standing time of 1 hour is sufficient.