A. G. Marants

Standardization of the refractory products for the slide gates of steelcasting ladles

ConclusionsNew technical specifications, viz., TU 14-8-185-75 and TU 14-8-213-76, for the refractory products for the slide gates of steelcasting ladles have been prepared and put into effect.The standardization of the types, dimensions, and technical specifications of the refractory products for slide gates will help to improve the quality of the products and accelerate the changeover to an advanced method of steelcasting.

Refractories based on fused pe riclase — Chromite material for vacuum steel refining plants

ConclusionsThe relevant technology was developed and production has started of high-quality refractories based on a high-density fused periclase —chromite material.The refractories are characterized by a low content in silica and silicates, well-developed direct bonds between the high-refractoriness minerals, and high indices for density, cold-crushing strength, thermal strength, refractoriness under a load, and in-vacuo stability to the action of slag and steel melts and the gases. The most favorable combination of properties was achieved when using starting materials of high-purity, fused periclase-chromite with a maximum grain size of 5 mm, batches with a low content of fine-ground components, high specific molding pressures, high firing temperatures, and long holding times at the peak temperature.The refractories are designed for the lining of the pipe, bottom, and walls of the chamber of equipment for vacuum steel refining and can be used with good results in the lining of converters, electric-arc and plasma furnaces, and other installations for melting high-temperature materials.

Castings from a corundum melt

ConclusionsThe apparent density of castings from Kor-95 corundum depends on the chemical and mineral compositions of the alumina, the temperature and degree of carburization of the melt, the volume of the shrinkage head, and the weight of the casting.Corundum castings with a maximum apparent density of 3.5–3.7 g/cm3 can be produced using a large shrinkage head (60–80% on the product volume for castings weighing more than 20 kg and 100–120% for castings weighing less than 20 kg) which is subsequently cut off with a diamond tool together with the regions of gaseous porosity and shrinkage flaws.

Prospects for using a cyclone melter for obtaining fused refractories

ConclusionsStudies showed that it is in principle possible to use melting cyclones employing oxygen-enriched blast for obtaining fusion cast refractories with fusion points of 1800–1900°C providing the melt is collected in a heated collecter. The dust emission during cyclone melting does not exceed 5%, which ensures the production of melt whose chemical composition is close to the original batch.

Some technological features of the production of fusion-cast corundum products

ConclusionsMeasurements of the temperature cooling of corundum melt in graphite molds (from 2100° C and below) can be made with tungsten — rhenium thermocouples.The relationship was established between the structural features of corundum castings and the initial temperature of the melt.The intensity of cooling the cast in the mold made from material with a high thermal conductivity (graphite, metal) in the setting period is determined by the total specific heat of the mold.The most dangerous period in regard to the formation of cracks in corundum castings is the period from the end of setting to the moment of reducing the drop in temperature inside the casting to about 150–100° C.

Refractories made from magnesite powder manufactured by the slurry process

ConclusionsIt was found under plant conditions that when magnesite slurry powder is used to make bricks, there is no longer any need to age them first, or any need for other methods of hydrating the free calcium oxide in the powder or charge.Magnesite slurry powder containing 86% MgO, 5% SiO2 and 4.5% CaO can be used as a basis for making magnesite-chrome and chrome-magnesite bricks which come up to the required standards, provided the chromite ore contains a considerable proportion finer than 0.09 mm or a fine-ground mixture of chromite ore and magnesite powder.