Unfired refractories for uphill teeming

Teeming of bearing and structural steels through a bottom gate lined with unfired refractories is described for the first time. Tests showed that unfired hoppers, spiders, and central and siphon tubes, produced using a charge of 65% chamotte, 17.5% clay, and 17.5% kaolin, possess high heat resistance and strength and reduced erosion by a molten metal stream, and their operational properties are not affected by shrinkage after use. The unfired articles have proved to be suitable for uphill teeming. The quality of the metal teemed through the unfired bottom refractories meets the specifications required for non-metallic inclusions. 2 refs.