Modifying <Emphasis Type="Italic">CRI</Emphasis> and <Emphasis Type="Italic">CSR</Emphasis> values of coke

The influence of the following factors on the reactivity CRI and hot strength CSR in industrial coking is studied: eliminating bituminous coal from the coal batch; considerably increasing the coking periods; and significantly reducing the ash content of the batch. Batch composition such that the coke quality meets the needs of export customers (including requirements regarding CRI and CSR) is identified. Sharp deterioration in CRI and CSR is seen when the batch includes coal with high ash basicity and coal concentrate that is heavily contaminated with intermediate products.     

Assessing the metallurgical coke produced at OAO NLMK

Up-to-date methods of assessing coal and coke quality have been introduced at OAO NLMK. Industrial coking tests using high-quality Russian and imported coal have been conducted to boost coke quality. Algorithms are proposed for predicting the postreactive strength (CSR) and reactivity (CRI) of coke as a function of the batch characteristics.     

Industrial utilization of spent ion-exchange resin in the coke battery

Experimental coking with spent ion-exchange resins as an additive in the coal batch is considered; rammed batch is employed. Both box coking and large-scale coking are considered; the resin content in the batch is 1–5 wt %. The influence of the resins on coke quality is assessed. The coal blend used in industrial coke production is employed. Adding small quantities of resin (<5 wt %) to the batch improves the coke’s cold strength M ₈₀ and M ₄₀, without impairment of CRI and CSR. The quality of the coal tar and the organized gas emission remains unchanged. Hence, spent ion-exchange resins may be recycled by adding small quantities (3%) to the coal batch in coke production.     

Influence of batch composition and clinkering properties on the hot strength of coke and blast-furnace operation

The relation of the basic characteristics of coking batch to the hot strength CSR and reactivity CRI of coke is established. The plastic layer of the batch components influences CRI and CSR. The relation of the batch composition to CSR and CRI is determined. When using enrichment batch that contains ～50.4% cokeforming coal, the best results are obtained: CSR = 61.8–62.3% and CRI = 26.4–26.7%.     

Mechanical and physicochemical properties of coke produced by wet and dry slaking

Relations of the form M ₁₀ = f(M ₂₅), CSR = f(M ₂₅), CRI = f(M ₁₀) and CSR = f(CRI) are investigated for wet- and dry-slaked coke. The corresponding mathematical models-linear regression equations-describe these relations with a mean square deviation that is consistent with the relevant standards. The discrepancy between the predicted and actual characteristics of the coke may be considerably increased by adopting special preparation methods and/or by increased basicity of the ash content in the batch.     

Influence of the batch’s ash content on coke quality (CRI and CSR)

To permit more precise assessment of Russia’s coal reserves, the influence of the batch’s ash content on the reactivity (CRI) and postreactive strength (CSR) of the coke produced is analyzed.     

Preparation of coal batch for top loading: Experimental research

The packing density is an important parameter of coal batch in the top loading of coke ovens. By careful adjustment of the packing density, the coke quality may be maximized and the productivity of the coke battery may be enhanced. Various methods of compacting coal batch for top loading are considered. The influence of batch preparation on the charge density and quality of the coke produced (CRI and CSR) is assessed.     

Predicting ash basicity from its density

Physical determination of the chemical composition and actual density of the ash in coal and coal batch reveals that they are statistically related, as confirmed by high values of the multiple-correlation and determination coefficients. The proposed method of determining the actual density of the ash in coal and batch permits significantly more rapid prediction of the reactivity CRI and postreactive strength CSR of coke produced from such coal (batch).     

Relation between the coking properties and quality of coke

On the basis of laboratory data for production batch employed at AO Evraz NTMK and AO Evraz ZSMK, including batch that contains Ulug-Khem coal, a coking characteristic is proposed. This characteristic permits relatively precise prediction of CSR and CRI. Its relation with the quality of coke produced by the classical method and from rammed coal batch is analyzed.     

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.     

Optimizing the batch composition at OAO Moskoks

A multiple-regression equation is derived to describe the change in hot strength CSR of coke as a function of the coal quality in the batch and the coking parameters. The influence of these parameters on the hot strength of coke is analyzed. A computer program is written for calculating the optimal batch composition on the basis of the available coal.     

Assessing the ash composition and properties in mathematical models of <Emphasis Type="Italic">CSR</Emphasis> and <Emphasis Type="Italic">CRI</Emphasis>: A review

Quantitative characteristics of the chemical composition (U _b and I _b ) and properties (melting point, actual density) of ash used in predicting CSR and CRI for coke are analyzed. It is found that U _b and I _b are interdependent but are not analogs, since the first includes the ash content of the coal, whose variation affects the ash composition. Because of the considerable discrepancy in the U _b and I _b values calculated from the actual density or chemical composition of the ash and used in the prediction of CSR and CRI, there will be a great discrepancy between the actual and predicted values of CSR and CRI (7–11%).     

Influence of the composition of coal ash on its flow temperature and on the <Emphasis Type="Italic">CSR</Emphasis> and <Emphasis Type="Italic">CRI</Emphasis> values of the coke produced

Two sets of experimental data characterizing the chemical composition of coal ash, its flow temperature t _c, and the CSR and CRI values of the coke from such coal are analyzed. The results indicate that the content of four oxides (SiO₂, Fe₂O₃, CaO, and Na₂O) may be used to predict t _c and also CSR and CRI in mathematical models. Models of the form y = a(I ₄) ^b , where y = t _c, CSR, or CRI and I ₄ = SiO₂/(Fe₂O₃ + CaO + Na₂O), adequately describe the experimental data within the range considered.     

Group chemical composition of coal batch and reactivity of coke. Part 2

The dependence of CRI and CSR on the group chemical composition of coal and coal batch is investigated. This dependence is associated with change in the coal properties in the plastic state.     

Influence of the reactivity of coke on blast-furnace performance

The cold strength M ₂₅₍₄₀₎ and M ₁₀ of the coke determines the gas permeability of the batch bed in the blast furnace down to the viscoplastic zone of the ore and the coke windows in that zone. The hot characteristics CRI and CSR determine the mechanical strength of the coke in the lower part of the furnace batch, in and below the viscoplastic zone, including the furnace well. It is wrong to regard the hot and cold characteristics as alternatives, since they describe different conditions; the significance of each one should be acknowledged. The coke consumption may be reduced with increase in reactivity of the coke, so long as the high initial strength of the coke is maintained. The minimum permissible reactivity of the coke without clogging of the hearth depends on the operating conditions in the specific blast furnace.     

Petrographic aspects of the hot strength of coke

The strength CSR of metallurgical coke after high-temperature reaction with CO₂ is determined by the depth of reaction and depends on the petrographic composition of the initial coal, the degree of metamorphic development, and the content of catalytically active ash components. Qualitative aspects of coke’s hot strength are reflected in the mathematical model, whose parameters include the vitrinite content Vt in the batch, the inertinite content I, the reflective index R _o,r of vitrinite, and the basicity index of the ash.     

Influence of the Batch Composition at AO EVRAZ NTMK on the Coke Quality and Pulverized-Coal Consumption

The clinkering, coking, and lean components of the coking batch at AO EVRAZ NTMK are experimentally studied. On the basis of the laboratory coking of 67 versions of the production batch at AO EVRAZ NTMK, with different content and properties of the clinkering, coking, and lean components, the formation of the coke’s CSR and CRI values is analyzed. A mathematical model is developed for predicting the coke quality on the basis of the batch characteristics. The pulverized-coal consumption at the blast furnaces is predicted for wet- and dry-quenched coke produced from different batches at AO EVRAZ NTMK.     

Predicting CSR and CRI of coke on the basis of the chemical and petrographic parameters of the coal batch and the coking conditions

A model is developed for predicting the postreactive strength CSR and reactivity CRI of coke. The model adequately reflects the dependence of these characteristics on the chemical and petrographic parameters of the coal batch, taking account of the batch preparation and coking period, as well as the slaking method.     

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.     

Predicting the reactivity and hot strength of coke on the basis of ash basicity

Models for predicting the reactivity and hot strength of coke are analyzed. The models take account, for example, of the genetic characteristics of the coal and the ash composition. Predictive formulas for CSR and CRI are proposed on the basis of the ash basicity in the coal batch.