I. Ya. Prokhorova

Interaction of basic refractories with converter slag

ConclusionsConverter slags based on a tar binder are located in the following order with respect to the increase in the degree of impregnation with slag: dolomite→dolomite-magnesite→magnesite. The greater degree of impregnation of magnesite refractories is due to recrystallization of the periclase grains, accompanied by an increase in their size, by saturation with magnesioferrite, and by dilatation of the reaction zone of the refractory.The degree of impregnation of the refractory with slag increases with the open porosity of the material and its impurity content.The presence of a coke residue in tar-bound and pitch-impregnated roasted refractories reduces their impregnation by fused slag.Converter refractories are located in the following order with respect to the degree of influence of preliminary heat treatment on the increase in the penetrability by slag: roasted, pitch-impregnated →heattreated→carbonized→roasted.

Fabrication Of Periclase-Carbon Refractories With An Antioxidant And Their Testing In A Lining Of A 370-ton Converter

Periclase-carbon refractories based on electrofused periclase with an additive of passivated aluminum have been tested in service in the top cone of a 370-ton converter of the Magnitogorsk Metallurgical Works. The lining with experimental refractories withstood 1501 heats whereas the endurance of commercial periclase-carbon refractories of grades PUPK-6 and PUPK-8 equals 1185–1416 heats. It was concluded that the periclase-carbon articles with an aluminum antioxidant have good prospects for lining converters.

Vibration machines for forming of refractory parts

ConclusionsLong service of vibromachines under production conditions has shown a number of indisputable advantages of this form of equipment:the capability of replacement of manual pneumatic ramming of shaped refractory parts, including blocks weighing up to 300 kg;the capability of production of shaped parts with improved service properties from poorly pressable stiff refractory mixtures;the capability of production of small lots of shaped refractory parts, the cost of which is lower than that of pressed as the result of elimination of costs for expensive molds.

Vibration pressing of refractory blocks of the lining of removable induction units

ConclusionsAt Krasnoyarsk Metallurgical Plant a method of vibropressing large shaped blocks for lining of the removable induction units of IAK-40 furnaces on a V-21 machine developed by the All-Russia Refractory Institute has been introduced. The method makes it possible to mechanize the laborious process of production of refractory parts, to increase labor productivity, and significantly improve working conditions.

A vibration machine for pressing of refractory blocks

At Krasnoyarsk Metallurgical Plant the removable induction units of channel furnaces are lined with individual blocks of complex configuration weighing up to 250 kg. For vibrofozuning of such parts it was necessary to develop new technical solutions directed toward increasing the effectiveness of the vibroaction and mechanization of the wzhole process, ineluding the operations of removal and transportation.

Sorption removal of oxygen by refractory materials from iron-nickel melts

ConclusionsIt is shown that it is possible in principle to carry out the sorption deoxygenation of a metal by refractories. A highly developed surface helps to provide a more complete sorption deoxygenation.Experimentally, periclase has better sorption properties than corundum.Most of the oxygen is removed from the melt in the first 5–10 min. The extent of the oxygen removal from the melt increases with an increase in its original concentration.

Refractories based on fused material in the dolomite-magnesite system

ConclusionsFused materials in the CaO-MgO system ware obtained by electric-arc firing of dolomite and magnesite. These materials have a dense fine-grain (unoriented) structure with bonds between the periclase and lime grains.The refractories based on the fused materials of the CaO-MgO system, whether unfired tar-bonded or fired pitch-impregnated, are better than the refractories based on sintered materials. They have greater density and strength; higher resistance to hydration and the effect of slag; and a lower rate of established deformation at operational temperatures.The tests in an experimental converter of tar-bonded unfired refractories based on fused materials showed that the wear for these products is ∼30% lower than for the corresponding refractories made from sintered materials. The wear of the fired, pitch-impregnated refractories based on fused materials is ≈1/2 that for the corresponding unfired refractories.

Vibroimpact forming of tarred converter refractories

ConclusionsUsing experimental vibroimpact equipment in production conditions studies were made of the vibroimpaet molding of tarred dolomite-magnesite converter refractories.Vibroconsolidation yields tar-containing dolomite-magnesite refractories at pressures of 1 kg/cm2 with much improved quality factors (density, homogeneity, strength), and also a much higher (by about one order) hydration resistance, than pressing at 1300 kg/cm2.The density of the vibromolded products is greatly affected by the quantity of tar in the body and its temperature. The quantity of tar added should be not less than 5.5%, and the body temperature 90–100°.To achieve a density in tarred dolomite-magnesite products by vibromolding, corresponding to the technical specifications, a process time of 30 sec is quite sufficient.

Effect of the viscosity of the resin on the properties of resin — Dolomite — Magnesite refractories

ConclusionsCalcined dolomite with a porosity up to 5% is not impregnated by resins of different viscosities (from 86 to 1200 sec at 40°C).Unfired products made from pastes in soft resins are characterized by a high degree of hydration and relatively low strength. Products in hard resins have better properties. The properties of the products after coking calcination are practically identical.Aging of the pastes does not substantially change the properties of unfired products. An increase in the aging time from 3 to 10 days leads to a noticeable worsening of the properties of the products after coking calcination.Since the properties of the products in resins of different viscosity after coking calcination are practically identical, in the production of resindolomite — magnesite products for converters, successful use can be made of resins of different viscosity, but with a coking number no less than 28–32%. The choice of the resin is determined by the technological flowsheet of the process for production of converter refractories: resins with low viscosity (C4010 up to 100 sec) by the cold process, resins with high viscosity (C4010 more than 1000 sec) by the hot process for preparation of the products.

The effect of ferrosilicon additions on the phase composition and properties of graphite-fireclay products

ConclusionsAdding 75%-ferrosilicon in amounts of 10–15 % to compositions of graphite-fireclay bodies contributes to the production of specimens whose properties are not inferior to articles made from bodies containing elemental silicon.In terms of phase composition, specimens with 75 %-ferrosilicon are close to articles with elemental silicon in them. During the firing of specimens containing 75 %-ferrosilicon, as with specimens containing elemental silicon, we get the formation ofΒ-silicon carbide which leads to the production of high-grade articles.Adding 45 %-ferrosilicon instead of elemental silicon or instead of 75 %-ferrosilicon to the graphite-fireclay bodies imparts the properties of the fired specimens. With respect to the phase compositions, the specimens containing 45 %-ferrosilicon are very different from specimens containing elemental silicon and 75 %-ferrosilicon. In specimens containing 45 %-ferrosilicon, there is no Β-SiC; the new phase is a new formation of ferroalloy.