Improved process for firing ceramic substances having a high proportion of combustible substances including carbonaceous shales and apparatus for carrying out such process

摘要

931,186. Continuous kilns. HOUILLERES DU BASSIN DU NORD ET DU PAS-DECALAIS. Jan. 25, 1960 [Feb. 9, 1959], No. 2682/60. Class 51 (2). Ceramic products from carbonaceous shales of the type disclosed in Specification 931,185 are fired in a Hoffmann kiln comprising a treatment chamber divided by a central well 21, Fig. 8, a peripheral waste gas flue 24 with diagonally opposite offtakes 27 respectively controlled by dampers 28 and 29, and apertures 25 each controlled by a damper 26 joining said chamber and said flue. During the initial heating period when considerable evolution of combustible substances takes place, the temperature is controlled by supplying an excess of air through roof ports 8, Fig. 5, and extracting large quantities of waste gases through dampered openings 6 into waste gas flue 4. The waste gases may be used for drying the ware. For a time combustion of evolved substances makes the firing process self-sustaining, but eventually, and particularly when glazing, cool dust is supplied through roof ports 9. In the final cooling zone 11 cooling air supplied through roof ports 10 passes partly in the direction of the arrow 15 to join the waste gases and partly through dampered openings 6f direct to the flue 4.