Periclase-carbon parts with a graphite kish (periclase-carbon refractories for steel melting production)

Abstract

The Eastern Refractory Institute together with the Dnepropetrovsk Metallurgical Institute and the Chelyabinsk Metallurgical Combine has developed and tested a method of production of periclase-carbon parts from periclase-lime patching powders with the addition of graphite kish. This method may also be introduced in the tar-bonded dolomite shops of Krivoi Rog and Karaganda Combines and other steel plants without any capital expenditures.Type PPIM-78 periclase-lime patching powder (GOST 24862-81), graphite kish, which is waste of steel melting and blast furnace production and is a metal-graphite-silicate composition, and an organic carbon-containing binder were used as the original materials (Table i).Graphite kish, at present removed by the cyclones of oxygen converter shops, has not obtained the necessary economic rating and annually 200,000 tons of high-quality graphite concentrate containing 50-80% graphite goes to the dump.* Under laboratory conditions these materials were mixed with the binder, cylindrical specimens with a diameter and height of 50 mm were pressed under a pressure of 125 N/mm 2, and they were fired in air at 1600~ for 5 h (Table 2).With an increase in the quantity of graphite kish the compressive strength of the specimens decreases while the porosity remains practically the same. The lowest degree of burning off of the carbon is observed in the mixtures containing 15% graphite kish. The periclasecarbon specimens with natural graphite have high porosity and a 1.5-2 times greater degree of burning off of the carbon than the specimens with graphite kish.In the Tar-bonded Dolomite Shop of Chelyabinsk Metallurgical Combine 116.2 tons of periclase-carbon parts with the addition of graphite kish were produced. The parts were prepared using two methods, successive and parallel mixing of the components..After pressing the parts were removed from the press by an automatic ejector, stacked on a pallet, and unloaded in finished product storage (Table 3).The periclase carbon parts produced by parallel mixing of the components had higher strength and increased density.Parallel mixing of the components causes simultaneous coating of the grains of all of the components with the graphite kish, which decreases the coefficient of internal friction of all of the grains simultaneously, increases the plasticity and homogeneity of the mixture, and creates a denser structure in forming of them.The periclase-carbon parts were tested in the lining of a 130-ton converter in the Oxygen Converter Shop of Chelyabinsk Metallurgical Combine. With them 1/3 of the converter lining at the top was made, starting from the 28th row to the mouth.In heating of the converter it was established that the graphite kish did not burn off. The service conditions of the converter were steels melted transformer, ball bearing, lowcarbon, and low-alloy, heat time 40-50 min, temperature of the metal at pouring 1590-1630~ and oxygen consumption per ton of steel 60-65 m 3.