V. Ya. Gushchin

Improvement of the manufacturing process of carbon-containing refractories at magnezit works JSC and some results of their use in various metallurgical plants

The Magnezit Works Company has developed and is installing a technology for manufacturing spinel-periclase-carbon refractories based on molten powders of periclase and aluminomagnesia spinel. Pilot tests of the refractories in a steel-melting ladle have shown that they can compete with the best foreign counterparts. The effectiveness of use of ShPUP refractories in the functional layer of the bottom and the branch pipe of the vacuum chamber of a batch degasser is shown. A study directed at creation of ShPUP refractories with elevated operating characteristics for the slag lines of ladles is carried out. The application range of the refractories is expected to widen.

Implementation of a production technology for refractories of the MgO-Al2O3-C system

It is shown that PShUS-2 products produced by the Dinur JSC are quite comparable in exterior appearance and accuracy of dimensions to PL 9310 periclase-carbon refractories manufactured by Magnesit Werke (Germany) with the same wear rate. Their average durability is no less than 45–50 heats. The Kompozit-Ural JSC and the Kombinat Magnezit JSC in cooperation with the Dinur JSC have improved the production technology for refractories of the MgO-Al2O3-C system to produce a variety of articles with the aim of utilizing as much as possible the reserve of their durability in various zones and sections of metallurgical units.

Mass exchange in the tuyere zone of the lining of converters with bottom fuel-oxygen blowing of vanadium iron

The authors test the corrosion and wear resistance of several refractories used in the tuyere zone of furnaces to the effects of temperature and slags consisting of vanadium oxides, silicates, and iron. Their investigation leads them to make the following recommendations to increase this properties: the acid iron-silicate composition of the slags mandates the use of high-chrome refractories; an increase in the thermal-shock resistance and oxidation resistance can be achieved by preliminary impregnation of the refractories with fusible metals such as aluminium, silicon, and magnesium; and to reduce the slag impregnation and accelerate the formation of the cermet structure in chromite-periclase refractories it is necessary to carry out preliminary impregnation with carbonaceous material with a high coke residue. The contribution of these recommendations to the overall service and efficiency of the furnace is cited.

Tests of refractories in argon-oxygen refining of metal

ConclusionsAs the result of comparative tests of refractories of different forms in the lining of the cylindrical portion of a 10-ton converter using argon-oxygen refining it was established that the most resistant of the tested materials is the periclase-spinellide refractory with the addition of chrome-alumina-spinellide. These parts may be recommended for lining the cylindrical portion of a pilot production argon-oxygen refining unit.

Comparative tests of refractories in the tuyere zones of a converter with bottom oxygen blowing

For the purpose of investigation of highly resistant refractories for use in the tuyere zones of the bottoms of converters with bottom oxygen blowing after semiproduction tests, comparative tests were made of different domestic refractories under production conditions. Tuyere refractories in the form of 280x225x190 mm blocks with a center channel under the 30 mm diameter tuyere were produced for the investigation at Magnesite Combine in TsMI-2. Blocks of the type PKhK periclase-chromite composition, type PShGP periclase with a spinel binder, type KhM chromite-periclase, KhPT, and type MKhVP periclasechromite were produced. The chemical compositions of the mixtures for production of the parts are given. Vanadium iron was blown and the bottom fuel-oxygen blowing of the vanadium iron was done using two variations. The amount of wear of the blocks and tuyeres is presented and a chemical analysis of the samples of parts after service is shown. Under the conditions of the investigation conducted, KhM chromite-periclase refractories showed the greatest resistance.

Comparative tests of various forms of refractories in the bottom of a converter in the blowing of vanadium iron

Comparative tests have been made of different forms of refractories in the zone near the tuyeres of the bottom of a 300-kg converter in bottom blowing of vanadium iron into steel. The various types of refractories that were prepared for testing in the experimental converter were: KhM chromite periclase; PkhP periclase-chromite; PShV and PShPKhV, periclase-spinellide; fired fused periclase base experimental composition; and unfired type PGBP periclase-carbon based on fused periclase. The basic properties of the refractories used are shown.

Use of increased quality sulfite-yeast mash for the production of mangnesia refractories

ConclusionsLaboratory investigations and production tests established that with the use of sulfite-yeast mash concentrates meeting the requirements of Technical Specification 81-04-546-79 as a temporary binder, unfired refractory parts possess higher strength than with the use of sulfite-yeast mash concentrates to Industry Standard 81-79-74, which is particularly important in mechanized removal of parts from the press.Sulfite-yeast mash concentrates meeting the requirements of Technical Specification 81-04-546-79 are recommended for introduction as a temporary binder in pressing of magnesia parts.

Some properties of refractories based on clinkers with various concentrations of calcium oxide

ConclusionsWe have studied the properties of the refractories prepared from periclase-lime clinkers with a CaO concentration of 2 to 60%. It is established that as the concentration of CaO is increased, the rate also increased at 1500–1650°C; the degree of dissolution of the refractories in slag is reduced; and in connection with this, their wear resistance is also lowered when tested under conditions simulating, in a first approximation, normal production conditions.The wear-resistance of the fired, pitch-impregnated refractories is higher than for the resin-bonded refractories of the same composition; this is the result of their greater density and strength at the test temperatures. The stability of the resin-bonded refractories made from synthetic clinker with 20% CaO is roughly 20% higher and that of the pitchimpregnated fired refractory 40–50% higher than the resistance of the resin-magnesite refractories normally used in production.

Effect of the decarbonization cycle for dolomite and magnesite on the sintering of powders

ConclusionsA study was made of the effect of the decarbonization schedule for dolomite and magnesite on the activity of the powders in relation to sintering. During rapid heating and with the minimum soaking at the final temperature of calcination, in. conditions of complete decarbonization for the original materials, it is possible to obtain caustic powders with a high specific surface and defect concentration in the lattices of MgO and CaO, which predetermines their hydration and sintering activity. With the optimum conditions of decarbonization for the powdered dolomite and magnesite the maximum densities of the fired briquets based on hydrated powders (respectively, 3.34 and 3.42 g/em3) are obtained with moderate firing temperatures (1500 and 1600°C).

Production and service-testing of refractories based on flotation-concentrated magnesite

ConclusionsFlotation-concentrated magnesite and pure and concentrated chromite were used for producing high-temperature fired magnesite, magnesite-chromite, and periclase-spinel refractories which, compared with ordinary types, contained less silicates and, more direct bonds between the high-refractoriness minerals so that their refractoriness under a load and their thermal strength were higher.In the lining of 100-ton converters for steel, the durability of the experimental magnesite refractory produced from concentrated magnesite and tar-impregnated was 19% better than that of ordinary tarbonded magnesite brick.In the lining of the tuyere zone and of the zone above it in 20-ton and 30-ton converters for copper and nickel, the durability of the experimental magnesite-chromite and periclase-spinel refractories produced from concentrated magnesite and concentrated and pure chromite was 30–35% better than that of ordinary MKhS and PShS type refractories.