E. Ya. Shapiro

Increasing the resistance of oxygen converter linings

ConclusionsWe developed a. differentiated construction for converter linings using tarred dolomite and periclase — spinel refractories in sites most prone to erosion: the throat, the neck, and the upper cylindrical parts on the pivot sides. Taking into account the topography of the wear we selected a rational profile for the working layer of the lining with which we obtained a higher and more uniform resistance.We developed and introduced a production technology for tarred dolomite refractories by pressingbodies cooled to 35–45°C, using tar with an increased coke residue and a viscosity of C1040=40-50 sec as the bond.We also improved the order of feeding in the batch materials, introduced slag and blow cycles for converter melting, ensuring rapid finishing of the high-basic slag in the blow process, reducing the melting time and the number of heats produced with the blow, etc.As a result of improving the quality of the tarred dolomite refractories, the introduction of the differentiated (with respect to thickness and types of refractories used) constructions for the linings, the use of rational firing cycles for the linings, improvements and stabilization in the quality of the batch materials, and improvements in the converter melting technology, the average life of the converter linings increased to 612 heats and the total consumption of refractories dropped to 2.95 kg/ton of steel; the maximum resistance reached 646 heats.The increase in the life of the linings ensured regular operation of the converter shop and provided a substantial increase in steel output.

Testing MKB-75 mullite-corundum articles in linings of casting ladles

The West Siberian Integrated Iron-and-Steel Works has tested in 350-ton casting ladles mullite-corundum refractories of grade MKB-75 (TU 14-8-633-95) produced by the Semiluki Refractory Plant. The use of these refractories in the ladles for casting steel into molds provides an endurance of 40 heats without replacing the slag zone or the bottom, which is 1.5 times higher than the endurance of ladles lined with conventional KVKB refractories. The use of MKB-75 refractories for continuous casting is inexpedient because of the elevated specific consumption and low endurance of the refractories.

Improvement and introduction of the lining of a gas-oxygen refining vessel

ConclusionsA design of lining differentiated by thickness and form of refractories used has been developed and introduced in Dnepr Special Steel Plant for the first time in the USSR for a vessel for gas-oxygen refining of low-carbon and corrosion-resistant types of steel specifying use in the working layer of the lining of:type BPGK periclase-carbon refractories in the bottom (920 mm);type PShPKh periclase-spinellide refractories with addition of fused chrome-alumina-spinellide in combination with PKhK refractories in the housing (690 mm) and throat (460 mm). The average life of such a lining is 63 heats and the maximum 73 heats under unfavorable operating conditions of the vessel.With an increase in the melting of low-carbon types of steel a thicker design of lining with a variable lining thickness in the cylindrical housing of the vessel (from 690 to 920 mm) with an increase in the power of its drive mechanisms is recommended for introduction. In the experimental campaigns the maximum life of the thickened lining reached 80 heats. For the purpose of further increasing the gas-oxygen refining vessel life it is primarily necessary to improve its operating conditions, for which there are very signifcant reserves, and also to accelerate work on introduction of torch guniting.

Structure evolution in periclase-carbon refractories at elevated temperatures

ConclusionsAt high temperatures, periclase-carbon systems exhibit a significant change in their phase composition and spatial distribution of the oxide and the carbonaceous components. The structure evolution of the periclase-carbon refractories occurs due to sintering of the mineralogical filler under the conditions involving a change in the volumetric proportions of the oxide and the carbonaceous phases because of the oxidation-reduction reactions.

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.