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Etude de l'oxydation thermique des composants carbones dans des refractaires de pises corindon-graphite et periclase-graphite contenant des liants phosphates

On etudie l'effet de liants phosphates (solutions aqueuses d'acide ortho-phosphorique et de polyphosphate) et d'un liant silicate (verre soluble) sur la cinetique d'oxydation de poudres de graphite utilisees dans les pises refractaires

The possibility in principle of the production and application of ramming forsterite mixtures from olivinites of the weathering crust of the Kovdorsk Massif under the conditions of converter production at the Severstal' JSC is described.

Tarasovskii Deposit quartzite wastes were investigated. The possibility of use of quartzite wastes of the 2-0 mm fraction was established. An experimental production lot of ramming compound of these wastes was produced at Tarasovskii Mine Administration and tested with positive results in the linings of 350-ton steel teeming ladles of Novolipetsk Metallurgical Combine.

Ramming mixtures with a carbon-containing component and mullite-corundum chamotte from Chinese bauxites instead of electrofused corundum have been developed for linings of cupolas designed for a prolonged continuous melting campaign. Ramming mixtures of grade MMKU are produced by the Semiluki Refractory Plant in correspondence with modification No. 2 of TU 14-8-559-88. Use of the mixture in the lining of a bottom, a hearth, and a compression siphon provided an endurance of the cupola equal to that of a lining from a conventional mixture based on electrofused corundum.

It has been established that orthophosphoric acid, which is used as an antifreeze moistener in ramming mixtures for sand-blasting ramming of walls of steel-teeming ladles, can be replaced by an aqueous solution of sodium acetate, a waste product of the Kaluzhskii Integrated Works of Synthetic Aromatic Substances.

The slag resistance of a silica ramming compound increases more than twofold with the addition of 10% graphite.

Electrofused ZrO2 is the best filler for a phosphate-bonded zirconia ramming compound. The bond should contain an addition of fine-ground monoclinic ZrO2.

An investigation was carried out of the interaction of a phosphate-bonded rammed zirconia compound with molten stainless steel in the presence of (U, Pu)O2.

Trials were carried out with a ramming compound consisting of 80% zirconia partly stabilized in cubic form and 20% monoclinic zirconia binder activated by fine-grinding. The grain size distribution of the compound was 50% fraction 2−0.5 mm, 10% 0.5−0.09 mm, and 40% finer than 0.09 mm. This type of compound possesses adequate strength and high spalling resistance and is suitable for lining induction furnaces for heating billets to 2000–2300°C. It can also be used as heat insulation in other high-temperature equipment in which the medium used does not erode the lining.

Dead burned magnesite without free lime and with an alcohol sulfite binder is recommended for the production of carbon free ramming mixtures. Magnesite mixtures with the above binder retain high refractoriness and are sufficiently resistant to the effects of hydration in drying and firing rammed bottoms. In regard to firing properties they are superior to mixtures with fusible binders. Thoroughly rammed mixtures with a sufficient amount of fines produce a highly resistant bottom in electric steel-melting furnaces. A gradual sintering of the rammed mixtures occurs under the action of the migration of liquid metals at high temperatures in service. It is, therefore, recommended to base the production of magnesite ramming mixtures for electric steelmelting furnaces on dead burned magnesite with an alcohol sulfite binder. The use of the above mixtures in the industry would facilitate ramming and repair work in comparison to mixtures to which carbon binders have been added.

We developed a composition for aluminous shrink-free ramming body with a phosphate bond, and a technology for manufacturing removable induction units for low-frequency channel furnaces used for smelting copper and copper alloys. The induction units had a long life — 22 months. The production of powders for ramming bodies is being arranged in refractories plants.

On the basis of sintered corundum and electrocorundum compositions were developed for ramming bodies containing phosphoric acid which can be recommended for making the bottoms of soaking pits.

Ramming compounds based on Latnensk clay-containing quartz sand and intended for the monolithic lining of steelcasting ladles were developed and tested and are now in production. The average durability of the lining of the 180-ton steelcasting ladles of converter section No. 1 of the Novolipetsk Metallurgical Plant is 9–10 melts when it consists of a ramming compound produced from Latnensk quartz sand. The lining becomes unserviceable owing to the low durability of the working layer of the bottom. When using a ramming compound based on Chasov-Yar semifatty sand, the lining of the lateral parts of the ladle bottom and that of the slag zone are severely eroded after 7–8 melts.

A composition was developed for the industrial production, at the Kazogneupor factory, of mullite-corundum and corundum ramming compounds without kaolinite-containing component with a bond made of orthophosphoric acid. The necessary degree of tamping for the compound is provided by the presence, in the finely milled constituent, of fine-grained electrofused corundum with particle sizes of less than 12 μm in amounts of at least 50% (parts by weight) of the content of finely milled constituent. Compounds of this kind are being used for lining: induction channel furnaces for storing iron, casting plants, induction furnaces for casting iron under pressure, and the bottoms of soaking pits with walking hearths of rolling machines.

An investigation was carried out of the physico- and thermomechanical properties of ACP-bonded zircon ramming compounds, of the conditions for their drying and firing processes, and of their solid-solution interaction with a mixed (U, Pu)O2 nuclear fuel.

The composition was developed for a high-alumina chrome-aluminophosphate bonded ramming compound for the lining of the runners of high-frequency induction furnaces for melting cast iron. Industrial scale tests showed that these compounds are very durable and remain serviceable for two and a half to three months. The results of this investigation make it possible to recommend that industrial trials be carried out with runners fabricated from ramming compounds containing added orthophosphoric acid which are produced by the Semiluk Refractories Plant and supplied in ready-for-use form.