OAO EVRAZ ZSMK Research Articles

Modification of Refractory Components in Russian Coke-Oven Linings

To date, Giprokoks designs have been used for all Russian coke batteries. The condition of these coke batteries has been deteriorating from year to year. The mean life of Russian coke batteries is 32 years, with values of 35 years for OAO EVRAZ ZSMK, 40 years for OAO MMK, 33 years for OAO Altai Koks, and 30 years for PAO Severstal’. The condition of the coke ovens determines the stability of steel output. The Russian coke industry faces the challenge of renewing (modernizing) its worn-out coke batteries. Changes are proposed here in some refractory components used in coke-battery linings. These proposals may be of interest to coke-battery designers and to contractors preparing for the reconstruction (or construction) of coke batteries.

Nonparametric modeling of oxygen-converter processes

Preliminary data analysis in the identification of multidimensional discrete–continuous processes is considered. A method is proposed for generating a working sample from an initial training sample consisting of normal operating data. The method somewhat resembles the bootstrap process. In the present case, the process begins with a training sample that reflects the properties of the object to be identified. By means of the proposed method, the unknown stochastic dependence at the limit of definition of the corresponding input–output variables for the object may be automatically derived. The identification of the oxygen-converter process in converter shop 2 at OAO EVRAZ ZSMK is considered in the case with insufficient available information and gaps in the observation sample. The model is based on a new working sample containing both the measurements and data generated by the proposed method. By using the working sample as a training sample, the precision of identification is doubled.

Properties of Ulug Khem coal. 2. Quality of coke from batch containing Mezhegei coal

In the laboratory coking of production batches at OAO EVRAZ ZSMK, including those containing coal from the Elegest deposit, special attention is paid to batches with different quality of the clinkering, coking, and lean components, so as to determine the maximum possible content of Elegest coal in the batch if the coke produced is to be satisfactory quality for use in blast furnaces at OAO EVRAZ ZSMK with pulverized-coal injection.

Modification of steel with barium and strontium

The modification of steel by natural materials containing barium and strontium is considered. Thermodynamic modeling of the reduction of barium and strontium by silicon and aluminum is undertaken. The influence of modification by barium and strontium on the structure and mechanical properties of the steel is studied. The results are employed in the production of 25Γ2C and Γ13 steel in arc furnaces at the casting shop of OAO EVRAZ ZSMK and also in the production of 35XΓCЛ, 30XΓCЛ, and 12HЛ2ΦX steel at OAO Yurginskii Mashinostroitel’nyi Zavod by two-slag technology. The results of industrial tests indicate that modification with barium and strontium affects the microstructure and nonmetallic inclusions; and increases the margin of structural strength of the steel, estimated in terms of the yield point, strength, and impact strength at positive and negative temperatures. To identify the presence of barium and strontium in the steel, its structure is analyzed by means of extraction replicas on a transmission electron-diffraction microscope. The presence of barium and strontium within the grains indicates their reaction with the metallic melt, which affects the structure of the metallic matrix.

Improving the reduction and ladle treatment of Electrosteel for rail production

Research in the electrosmelting shop at OAO EVRAZ ZSMK indicates that, if inert gas is injected into molten rail steel in the ladle for 122 min, rather than 63 min, the quantity of nonmetallic oxide inclusions may be reduced, without impairing overall rail quality. Industrial experiments show that replacing MnS18 silicomanganese with FeMnSi30HP silicomanganese in the reduction of rail steel is economically effective in the electrosmelting shop at OAO EVRAZ ZSMK. The assimilation of carbon and silicon is increased by 4 and 13%, respectively. The mechanical properties and macrostructure of rails obtained by this experimental technology match those of the steel currently produced. According to the calculation results, the use of FeMnSi30HP ferroalloy provides savings of 13.99 and 32.64 rub/t for rails of category T1 and NE, respectively.

Resource-saving bar production on existing mills

Simulation of rolling in simple bar grooves permits analysis of the flow of surface layers of the billet and its influence on the stress–strain state of the metal in rolling; the conclusions are experimentally confirmed. The new groove system developed on the basis of those recommendations for the roughing rollers in the 250-2 continuous small-bar mill at OAO EVRAZ ZSMK is tested in industrial conditions. This system increases the product yield (reduces the rejection rate) by 3% in the production of bar from high-quality structural steel. The improvement in production efficiency due to the increase in productivity when slit rolling is introduced at the existing 250-1 continuous small-bar mill at OAO EVRAZ ZSMK is estimated. A method is proposed for determining the splitting conditions as a function of the required gain in productivity. Recommendations are made regarding the calculation of the rolling speed in the roughing and finishing cells. The change in total extrusion and rolling speed in the groups of cells during the production of rebar 10, rebar 12, and rebar 14 is recorded.

Mineral composition and crystalline structure of iron-bearing components in metallurgical waste

The waste stored in tailings and sludge pools at metallurgical enterprises—including wastes from raw-materials processing (extraction, enrichment, sintering, etc.), metallurgical processing, and ancillary processes—may be used for production purposes; in particular, it may prove valuable in ferrous metallurgy. With declining reserves of iron ore, the processing of industrial waste as a source of iron is of particular interest. For more than fifty years, production wastes—rock from coal enrichment, ash from coal combustion in the thermoelectric plant, gas-purification sludge, etc.—have been accumulating in the sludge pools at West Siberian Metallurgical Works (now OAO EVRAZ ZSMK). Since the sludge pools are now at the end of their working life, it is necessary to develop a technology for processing that waste. To assess the prospects for producing iron concentrates from the basic wastes in the sludge pool, the mineral composition and crystal-chemical structure of the iron-bearing minerals are investigated by means of Mossbauer spectroscopy, X-ray phase analysis, chemical analysis, and optical microscopy. Significant differences are observed in the types of iron in waste from different processes. That must be taken into account in developing the appropriate processing technology.

Organic-waste disposal in high-temperature metallurgical systems

Globally, organic waste is the largest component of hazardous waste. Chlorine-bearing organic waste is a particular environmental hazard. The main disposal method for organic waste is high-temperature combustion in special incinerators and in rotary cement furnaces. However, combustion is associated with the risk that secondary supertoxics such as dioxins and furans may be formed. Comparison of dioxin formation for waste combustion in incinerators, cement furnaces, and high-temperature metallurgical systems (oxygen converters) shows that oxygen converters are preferable, thanks to the high temperatures, intense heat and mass transfer, active oxidizing atmosphere, the presence of highly active basic slag, rapid cooling, and complete combustion of the waste gases. Data on the content of 17 dioxin and furan isomers in the dust transported by exhaust gas from converters containing paper and plastic waste at OAO EVRAZ ZSMK show that the total concentration is considerably below European standards for waste gases from stationary sources. No significant difference is observed in the concentrations and isomer profile of dioxins and furans in the experimental and standard melts.

Controlling the blast-furnace hearth

At OAO EVRAZ ZSMK, the operation of the blast-furnace hearth is regulated by means of special briquets with good granulometric composition, high iron content, and low impurity content. The briquet charge depends on the total iron-ore consumption, primarily in the intermediate region of the furnace. With steady briquet content (around 2.1% of the charge), the variation in the hearth obstruction is smooth and confined to a narrow range. When the briquets account for 1.0–2.5% of the total charge, the actual mean furnace productivity increases by 6.7%; the adjusted value increases by 3.5%. The actual coke consumption is reduced by 0.5%, and the adjusted value by 0.7%.

Plasma hardening of cast-iron rollers for channel production on a 450 mill at OAO EVRAZ ZSMK

The microstructure and microhardness of the hardened surface layers of cast-iron rollers are investigated. Plasma hardening of the grooves in a 450 mill is proposed. Industrial tests show that this approach extends roller life.

Geometric conditions in bar rolling

Analysis of the scope for more efficient bar rolling is considered; a method of rapid analysis is outlined. By this means, the geometric parameters of the rolling pathways may be represented by alternative groups of repeatedly transformed dimensionless factors, and the results of repeated transformation may be statistically analyzed, to obtain an assessment of competitiveness. The multivariant representation of the geometric conditions yields significantly more information, including unexpected technological reserves of the process. Such analysis provides a set of recommendations regarding the local correction of the deformation region in one or more passes of the steel through the mill. As an example, this approach is employed in assessing the potential for increasing the product yield in rolling structural-steel bar for cold extrusion and upsetting on small-bar and wire mills at OAO EVRAZ ZSMK. The proposed method may be used to improve the production of a wide range of steel bar.

Maintaining the quality of electrode pitch produced at OAO EVRAZ ZSMK

The quality of the coal tar used in the production of electrode pitch at OAO EVRAZ ZSMK is analyzed. The factors that impair pitch quality are identified, and remedial measures are proposed. Promising refinements of tar processing are noted.

Optimizing coke production at OAO EVRAZ ZSMK on the basis of the available coal

A model is proposed for predicting the coke strength (M 40 and M 10) and its NSC parameters CSR and CRI on the basis of the chemical and petrographic parameters of the coal. The model takes account of the chemical composition of the ash, the duration of coking, and the coke-slaking technology. On the basis of this model, the technological value of the coal types used at OAO EVRAZ ZSMK is assessed, and the batch composition is optimized to produce coke of elevated quality.

Introduction of dust-free coke discharge at OAO EVRAZ ZSMK

It is of great importance today to reduce the environmental impact of coke production. To that end, dust-free coke discharge has been adopted at OAO EVRAZ ZSMK.

Elegest coal in coking batch at OAO EVRAZ ZSMK

The coking of batch with different proportions of Elegest coal from the Ulug-Khemsk Basin is investigated in laboratory and production conditions. The mechanical strength of the coke is improved when such coal is used in the batch. At the same time, CSR falls, while CRI rises.

Selecting mixtures for continuous casting of rail steel at OAO EVRAZ ZSMK

Two versions of TSK-K-20 mixture are selected for the casting of 300 × 340 mm rail-steel billet on a radial continuous-casting machine: TSK-K-20B1 and TSK-K-20B1m. Their chemical composition and thermophysical characteristics are investigated. The mixtures ensure the required surface quality of the billet and the rolled product; the life of the submersible nozzles is at least 20 h. At present, these mixtures are used instead of ShOS-1 mixture for continuous casting in the electrosmelting shop.

Repair of coke-furnace linings by ceramic surfacing in the EvrazKokSibir’ coke shop

Defective sections of furnace-chamber linings must be cleaned by air-powder abrasion prior to ceramic surfacing. Devices for smoothing the walls may be used for this purpose. Data regarding the scorching of linings in coke batteries at OAO EVRAZ ZSMK are presented, along with the results of repairs by ceramic surfacing.