Pneumatic-hydrothermal drying and firing - of ceramic prods and silicate building mat-erials

摘要

The raw products are simultaneously dried and fired in an electrically heated, gas-tight unit. The charge-firing material is first heated without appreciable dehydration to 1-160 degrees C and then dried with vapour temps. of 1-200 degrees C and water vapour partial pressures of 0.1-6 atm. The material thus dried is heated to 550-950 degrees C at water vapour partial pressures of 0.1-6 atm. While this temp. is maintained final firing takes place, followed by cooling the firing material and unit. The water vapour escaping from the charge or firing material during the entire combined process is utilized as a drying medium in the drying phase and as a decisive parameter in the firing phase. This is effected by using fans to force the vapour, under an excess pressure of 0.1-6 atm. in the gas-tight apparatus, through the charge-firing material, formed as a hollow product, to generate convective heat and material transfer.