Coking Batch Research Articles

Alternative Components in Coking Batch: A Review

Alternative Components in Coking Batch: A Review

Preparation of Coking Batch in Vibrational Impact Equipment

Preparation of Coking Batch in Vibrational Impact Equipment

Better Use of Enriched UK Mezhegeyugol Coal in Coking Batch. 2. Composition of Concentrate Fractions and Coke Quality (CSR and CRI)

The mineral composition of coal from the Mezhegeyskaya mine (specifically, concentrate fractions of the machine classes >13.0, 0.5–13.0, and 13.0, 0.5–13.0, and <0.5 mm classes indicates the corresponding variation in coke quality (CSR and CRI). Experimental data permit practical recommendations regarding the enrichment of Mezhegeyskaya coal at EVRAZ enterprises so as to significantly increase the value of the concentrate and hence improve the CSR and CRI values of the coke. On that basis, the content of Mezhegeyskaya concentrate in the coking batch may be increased to 20.0%, as against 3.0–5.0% for traditionally enriched coal.

Coking of Batch with Elevated Gas-Coal Content at Azovstal Iron and Steel Works

By laboratory coking and experimental industrial coking, it is found that increasing the content of gas coal in the coking batch from 25 to 35% decreases the yield of blast-furnace coke and also its mechanical strength (M25, M10) and its hot strength CSR. Along with decrease in coke strength, its content of the >80 mm class declines and the contamination with the <25 mm class increases. In addition, the yield of all the basic coking byproducts (tar, raw benzene, ammonia, hydrogen sulfide, coke-oven gas) increases. After the coking of batch with increased gas-coal content, no disruption of the refractory lining or graphitization is noted. When blast-furnace coke produced from batch with elevated gas-coal content is used, the mean consumption of skip coke, blast-furnace coke, and coke nuts is increased. The oxygen concentration in the blast and the natural-gas consumption are slightly decreased. Economic calculations show that the decrease in cost of 1 t of hot metal associated with decrease in cost of the coking batch is $8.40.

Better Use of Enriched UK Mezhegeyugol Coal in Coking Batch

Abstract—Industrial coking data from Kuznetsk and Raspadsk concentrates consisting of coal from OOO UK Mezhegeyugol are analyzed to determine the strength M25 and M10 and the ratio CSR/CRI for the coke produced from such batch at AO EVRAZ NTMK. Preliminary limits are established on the optimal content of UK Mezhegeyugol coal in the coking batch. On the basis of industrial experiments, the optimal batch composition is determined, so that coke of satisfactory quality is produced at AO EVRAZ NTMK from batch with the maximum possible content of enriched UK Mezhegeyugol coal and the minimum content of third-party coal.

Coke Quality and the Prospects for Coking with Proprietary Coal Concentrates at AO EVRAZ NTMK

Abstract—The main suppliers of coal for coke production at AO EVRAZ NTMK are considered, along with the technological value of each concentrate in systems with wet and dry quenching. Alternative suppliers may be identified by ranking the concentrates. Laboratory and industrial coking reveals the influence of the coal concentrates on the quality of metallurgical coke. On that basis, their ideal content in the coking batch may be determined.

Determining the Vitrinite Reflectance of Coal from Its Fuel Ratio

The use of an empirical equation to calculate the vitrinite reflectance of coal from the fuel ratio Fr is considered. The fuel ratio is based on the fixed coal content (Cfixed = 100 – Ad – Vd) and the yield of volatiles (Vd). We investigate ten samples of bituminous coking coal (Zh coal) used as the clinkering component in the coking batch. Technical and elemental analysis indicates that the ash content of the samples is <10% and the yield of volatiles is 33.2–37.7%. Petrographic analysis shows that the vitrinite reflectance Ro,r = 0.825–0.982%, while the content of vitrinized components is 78–90%. The experimental data confirm that the relation between Ro,r and Fr may be used with high accuracy to calculate the vitrinite reflectance. Hence, the proposed method may be recommended to calculate the vitrinite reflectance for coal in the clinkering component of the coking batch.

Influence of Small Coal Particles in Coking Batch on Coal-Tar Quality

Traditional concepts regarding the influence of the entrainment of coal particles in coking on the quality of coal tar may usefully be expanded. In addition to increase in the ash content, the water content of the tar is increased. To eliminate stabilization of the emulsion forming in the condensation department, a limit of 10–13% has been imposed on the content of coal in the ≤0.2 mm class. Analysis of production data shows that the presence of coal particles smaller than 0.071 mm in the batch increases the density of the coal tar and its content of quinoline-insoluble materials. It is found that the water content of the tar is increased more strongly by the aromatic component of the coal than by the mineral component. The emulsifying properties of dusty coal are greatest for Zh coal and least for G coal.

Improving the Preparation of Coking Batch

Currently, the most promising blast-furnace technology involves pulverized-coal injection, and the most promising blast-furnace technology for coke production involves ramming the coal batch before delivery to the coke ovens, so as to ensure high packing density. In classic bed coking, the packing density of the coal batch is also of great importance. In the absence of mechanical methods (such as ramming or partial briquetting), the packing density mainly depends on the ash and moisture content and the degree of crushing of the batch. It follows from industrial tests in the coke plant at PAO ArcelorMittal Krivoy Rog and analysis of the multifactorial correlation of the strength M25 and wear resistance M10 with the packing density of the batch that, with decrease in packing density, the coke strength and wear resistance decline. That increases coke consumption and considerably complicates blast-furnace operation. Since improvement in coke quality entails decreasing the moisture content of the coal batch, a method has been developed for decreasing the moisture content directly in the silo, on the basis of osmosis and vacuum, that permits decrease in the coal’s moisture content to the optimal value, thereby boosting coke quality and improving blast-furnace performance. For example, it has been established that, in the blast-furnace shops at PAO ArcelorMittal Krivoy Rog, 1% decrease in M10 lowers the mean coke consumption by 5.5%. With increase in M25 by 1%, the mean coke consumption falls by 2.1%, on average.

Influence of the Crushing of Bituminous Batch on Coke Quality

Laboratory and industrial research confirms that decrease in the clinkering properties of bituminous coal when it is present to excess in the coking batch improves the strength of blast-furnace coke. If coal batch containing >70% bituminous coal is crushed until its content of the ≤3 mm class is 90%, the crushability Π25 may be increased by 1.8%, with decrease in the susceptibility to wear И10 by 0.8%. This behavior may be explained in that increase in the specific surface of the coal particles reduces the fluidity of the plastic mass and hence increases its viscosity. Consequently, the residence time of the gaseous products in the plastic zone increases. That results in the formation of a large quantity high-molecular gas, creating higher expansion pressure. The overall outcome is greater utilization of the destruction products as plasticizers; the formation of additional liquid from the gaseous products within the grains; and improvement in the contact conditions.

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.

Thermogravimetric Analysis of Moisture Desorption from Coal

In coke production, the moisture content of the initial coal is an important parameter. The moisture present in the pores of coal changes the properties of the coking batch. Note also that, together with methane and/or carbon dioxide, water may form gaseous hydrates in the coal bed. In the present work, to study the state of the moisture in coal, attention focuses on eight samples of natural gas saturated to constant moisture content in an atmosphere where the relative partial pressure of water vapor is 91%. The moisture sorbed from the atmosphere has a U-shaped dependence on the metamorphic stage of the coal, with a minimum at coking coal (K coal). In similar conditions, the more mature T and A coal contains twice as much moisture as K coal, while the younger D and G coal contains about four times as much moisture. Thermogravimetric analysis of coal samples saturated to constant moisture content permits calculation of the rate of mass loss and activation energy for the evaporation of moisture in the heating of the given samples. For each coal sample, the temperature range where the evaporation of moisture may be described by a first-order Arrhenius equation is determined. The upper limit of this range is compared with the temperature corresponding to maximum rate of mass loss and also with the temperature corresponding to the maximum thermal effect.

Predicting the Yield of Coking Products

The properties of coal concentrates are determined: the technical analysis, clinkering properties, petrographic and elementary analysis, and the product yields in coking. Structural characteristics of the coal’s organic mass are also calculated. The results obtained for Kuznetsk Basin coal are subjected to mathematical analysis. The experimental dependences obtained may be used to formulate optimal coking batch in actual production conditions.

Oxidation of coke with petroleum-based coking additives

The properties of coking batch may be stabilized by means of DK coking additive based on the products of petroleum pyrolysis, characterized by low ash content (Ad = 0.4%), high sulfur content (Std= 4.1%), and high yield of volatiles (Vdaf = 17.2%) relative to coal concentrates. Individual coking of DK coking additive yields a product (particle size >40 mm) with postreactive strength CSR = 77–79%, reactivity CRI = 18–22%, and density 1200–1400 kg/m3. Differential scanning calorimetry of experimental coke samples reveals six stages in their heat treatment in air: preliminary heating, intense oxidation, gasification of carbon, surface combustion of the gaseous products, their flare combustion, and oxidation of the residue. The use of DK coking additive in the coking batch shifts the oxidation process to higher temperatures and ensures the largest interval of heat liberation at elevated heating rate, with up to 50% DK additive. With increase in the content of DK additive from 30 to 50%, the activation energy is increased by 4.56 kJ/mol for each additional 10%. In that case, the supply of atmospheric oxygen to the combustion zone must be improved

Petroleum additives for coking batch

At OAO Gubakhinskii Koks, the influence of the content of coking additive in the batch on the operation of coke battery 2 is studied experimentally. The goal is to determine the maximum permissible content of petroleum additive in the batch for improvement in battery performance. Batch compositions are developed on the basis of the materials available at OAO Gubakhinskii Koks, with 25, 50, and 75% petroleum additive. After quenching, the experimental coke is sorted by size and loaded into rail cars, according to the standard production procedure, and studied by standard monitoring methods. With increase in the content of the petroleum additive from 10% (standard production batch) to 75%, the mechanical strength of the coke is improved: M 25 rises from 85.6 to 88.6%, while M 10 falls from 8.6 to 7.0%. Improvements in terms of CSR and CRI and the ash content of the coke are also seen. However, during discharge of the coke cake produced from batch with 50% and 75% additive, the discharge force required is increased. That may result in damage to the chamber lining. The results indicate that the content of petroleum additive in the coking batch may be increased above 50%, but more detailed study is required.

Optimizing the composition of coal batch

The optimality of coking batch may be assessed on the basis of the coefficient Kopt(Vt). A method is proposed for determining Kopt(Vt) by means of petrographic and reflectogram analysis. This approach permits ongoing assessment of the optimal composition of the coking batch and prediction of the coke’s mechanical strength.

Group chemical composition of coal batch and reactivity of coke. 3. Phase composition of the primary products of coal pyrolysis

The action of the group chemical composition of coal’s organic mass on its phase composition in the plastic state and hence on the coke quality is quantitatively described and experimentally verified.

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.

Group chemical composition of coal batch and reactivity of coke 1. Determining coke reactivity

With a view to finding correlations between coke reactivity and the coal batch employed, methods of determining coke reactivity are considered—in particular, the standard and pulsed methods. The kinetic equation fundamental to all methods of assessing the coke reactivity from the gasification rate constant is presented. The possibility of combining data obtained by different methods of estimating the coke reactivity is established.

Ensuring stable quality of blast-furnace coke

Blast-furnace performance is dependent on the coke quality and, above all, its stability. The stability of coke properties is ensured by effective homogenization of the coal components on storage and on blending crushed coal to form the coking batch.