GB1270062A - Process for treating moulded refractory - Google Patents

Abstract

1,270,062. Drying refractory materials. MAKOSID-WERKE AKEN VEB. 8 June, 1970, No. 27578/70. Heading F4G. To reduce the drying time of, and provide high mechanical strength in, moulded bricks 1 of refractory materials either having an MgO or Cr 2 O 3 (or a mixture) content of at least 50% by mass or having an SiO 2 content of at least 55% by mass, a moisture content of 1À4-5% by mass, up to 5% by mass of an adhesive, and a compressive strength of 20-30 kg./cm.<SP>2</SP> at room temperature, the moulded bricks 1 are trans ported through a continuous treatment tunnel in which the bricks 1 are subjected either to infrared radiation or to a counterflow of a drying medium (hot air or flue gases) at a temperature of 250-350‹ C. for 12-20 minutes, and then to a flow (in the transport direction) of cooling air at a temperature of 16-25‹ C. for 10-15 minutes, through nozzles extending across the width of the tunnel or spaced apart across the width of the tunnel, so as to have a moisture content less than 50% of the original aud a compressive strength of at least 80 kg./cm.<SP>2</SP>. Batches of spaced moulded bricks 1 are deposited by an automatic grab system (not shown) on a plate conveyer 2 of a continuous treatment tunnel, and transported step-by-step therethrough. The drying medium is heated by the waste heat from tunnel kilns, and the cooling air is supplied through five nozzles extending the full width of the conveyer 2 or five assemblies 5 of nozzles 4. In the tunnel, the atmosphere may contain CO 2 .