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.     

Determining the strength of coke under crushing forces

Despite the many characteristics of coal relating to its use as blast-furnace fuel, few characteristics have been proposed to predict the productivity of the furnace and its coke consumption. Drum tests of coke permit ample assessment of its ability to withstand mechanical loads (in particular, abrasive and impact forces). At the same time, models of coke failure in the blast furnace indicate that the crushing forces on the coke play an important role. Thanks to those forces, the mean piece size of the coke declines as it falls though the furnace. The method used to determine the coke’s ability to withstand abrasive and impact forces has been codified in GOST State Standards (in terms of the strength indices M ₂₅, M ₄₀, and M ₁₀). However, there is no standard method for assessing the ability of the coke to withstand crushing forces. To address that deficiency, a compact system for determination of the coke’s ability to withstand crushing forces is proposed: it consists of a press for the creation of compressive forces; a matrix with a punch in which the coke sample may be placed; and an instrument for measuring the compressive force (the crushing force). Values of the compressive strength determined using the new system are presented for various coke samples.     

焦炭反应性与反应后强度的关系及其影响因素探讨

为了很好地预测焦炭在高炉中的反应行为,对大量的焦炭进行了检测及数据的分析,说明焦炭反应性与反应后强度之间有良好的负相关性;对焦炭冷态强度与热态性能之间进行了对比,建议焦化企业在保证焦炭的冷态强度合格的同时,更要关注焦炭的热态性能指标;对影响焦炭反应性与反应后强度的反应温度、碱金属、钝化剂等因素进行了试验,指出在生产中应严格控制高炉操作温度,并在按国标方法测定时,加入一定浓度的碱类,以模拟高炉生产的实际过程。提出熄焦时采用一定浓度的硼砂溶液喷洒焦炭,可改善焦炭的热性能。     

Coke Quality and Blast-Furnace Performance

On the basis of six-year operational data for a 5000-m³ blast furnace, the dependence of the coke consumption on its strength M₂₅ and M₁₀ and the content of the >80 mm fraction is calculated by different methods. The quality of the coke has a clear influence on coke consumption and blast-furnace economics. As an illustration, for some of the equations derived, means are established for predicting the economic benefit associated with improving coke quality and reducing its consumption, in specific blast-furnace conditions.     

Information content of methods of determining coke reactivity

The reactivity of coke plays an important role in blast-furnace smelting. The reaction of carbon in coke with oxygen generates the heat required for various chemical reactions in the blast furnace. The reaction of carbon in coke with carbon dioxide and water vapor forms carbon monoxide and hydrogen, which reduce the iron and alloying elements from their oxides. As a result of these reactions, the strength of the coke pieces in the blast furnace is reduced, and they break down more as they move in the furnace batch, with consequent decrease in gas permeability of the batch column.     

Producing high-quality coke from blends of domestic and imported coal at PAO Zaporozhkoks

The evolution of quality requirements on blast-furnace coke indicates the need to use low-sulfur imported coal of the required quality. The best performance characteristics of European blast furnaces are noted. At such furnaces, with the injection of pulverized coal, the consumption of low-reactivity blast-furnace coke is 280.9–355.8 kg/t of hot metal. On the basis of the requirements imposed on coal used in the production of low-reactivity, low-sulfur, high-strength coke, an industrial coking method has been developed and tested at PAO Zaporozhkoks on the basis of Ukrainian, Russian, and United States coal of the required quality. The coke produced is tested in blast furnace 5 at PAO Zaporozhstal’. The results show that coke of improved quality may be obtained from batch containing 50% Ukrainian coal, 30% Russian coal, and 15% United States coal at PAO Zaporozhkoks. Thus, in the first 11 months of 2013, the quality of the blast-furnace coke produced was as follows: moisture content 3.6%; ash content 11.0%; sulfur content 0.78%; M ₁₀ = 6.3%; content of the >80 mm class 4.1%; content of the <25 mm class 3.1%; CRI = 31.8%; CSR = 51.9%.     

Examination of some effects of dry cooling on coke quality

A series of coals were carbonized, on the 250 kg scale under standardized conditions, to provide both dry-cooled and wet-quenched cokes which were subsequently subjected to reactivity and strength testing. The data from the tests of reactivity to CO₂ at ≈1000 °C support the view that dry coke cooling leads to lower reactivity, but examination of the porous structure in the pore size range > 5.45 μm and of the optical anisotropy of the coke carbon revealed no changes to account for this effect. Although the micum test indices were sometimes improved by dry coke cooling, the differences were not statistically significant. On the other hand, there was clear evidence of increased coke tensile strength. The effect of dry coke cooling on coke properties appears to be sufficient to exert some influence on the blast furnace coke rate and thereby on the economy of the dry-cooling process.     

Effective stabilization of coke properties

The efficiency in stabilizing coke properties is assessed on the basis of half of the coke savings in the production of 1 t of hot metal. The relation between the quality of the coke (M ₄₀, M ₁₀) and its consumption in the production of 1 t of hot metal is derived from literature data for blast furnaces in the United States and China. The cost of coke of different classes is taken in accordance with 2010 market prices. The maximum stabilization is estimated. The results are compared with data obtained on the basis of list prices for coke 01–06. The conclusion is that the effectiveness may be greater at high prices than at low prices.     

Influence of the size distribution of batch components on coke quality

Different degrees of crushing of coal in different technological groups, with constant rank and granulometric composition of the batch, significantly affect all the basic characteristics of coking: the packing density of the batch, the yield and strength (M ₂₅ and M ₁₀) of the coke, and its granulometric composition. That influence is practically always expressed through the products of factors (the contents of coals of different rank and different size class in the batch). This indicates systematic interaction of the components.     

Influence of batch properties and its preparation and coking conditions on the characteristics of coke

The influence of batch preparation on the properties of blast-furnace coke is considered for OAO Zapadno-Sibirskii Metallurgicheskii Kombinat. In particular, the influence of the batch composition and its preparation and heating conditions on the strength of blast-furnace coke is investigated. It is found that increasing the moisture content of the batch from 7.3 to 12.6% impairs coke strength: M ₁₀ changes from 7.8 to 9.4%. The mechanical strength is also reduced by increasing the ash content and reducing the piece size of K, OS, and KS coal.     

Improving the shaft smelting of minerals by changing the activity of coke

Metallurgical coke is a common fuel in smelting shaft furnaces. The properties of the coke largely determine furnace performance. If coking additives are used to stabilize the properties of the coal batch, coke of increased hot strength may be obtained, with reactivity CRI = 18–22% and density of the pieces 1200–1400 kg/m³. Industrial tests on a slag-cotton cupola furnace establish the variation in its performance when using experimental coke, with reduction in coke consumption by 0.20–0.25% and increase in heat input by 90 kW on average. The proportion of heat in the melt is increased here, along with the degree of incomplete combustion. The heat consumption in melting the initial components declines by 2.3% on average, while the total thermal efficiency of the system decreases by 1.8% for each additional 10% of the experimental coke.     

Optimizing the preparation of coal batch for coking at ChAO Makeevkoks

The expediency of introducing up-to-date systems in the preparation of coal batch for coking at ChAO Makeevkoks is evident if the quality of the coal concentrates employed is assessed in terms of technical, plastometric, petrographic, and granulometric characteristics. Coking trials indicate that separating out the small coal classes prior to final crushing significantly improves the technological characteristics (M ₂₅, M ₁₀) and structural parameters (the Ginzburg abrasive hardness and Gryaznov structural strength) of the blastfurnace coke produced. Introducing hydrocarbon briquets in the coal batch permits the utilization of coking waste without impairing the coke strength.     

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.     

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.     

Assessment of petrographic model for the prediction of coke strength

The strength of coke produced from Mongolian coal is calculated within the framework of Eremin’s petrographic model, on the basis of literature data from a maceral analysis of such coal. The model produces quantitatively correct values of the strength characteristics M ₂₅ and M ₁₀. The clinkering microstrength of coal grains for individual ranks and the postreactive strength CSR of the coke may also be estimated.     

安钢75t/h干熄焦经济效益综合评价

介绍了安钢75 t/h干熄焦在节约能源,提高焦炭质量,提高炼铁生产能力及环境改善(节能减排)等方面的直接经济效益。由于干熄焦的焦炭冷、热强度提高,可使高炉焦比降低2%,高炉生产能力提高1%,并且减少酚、氰、硫等污染物向大气中排放,环境效益较好。     

焦炭钝化剂在高炉炼铁中的应用研究

在焦炭上喷洒一定浓度的钝化剂溶液,可防止高温下焦炭气孔壁变薄而粉化,减少高温下焦炭破碎,有利于降低高炉中焦炭的热反应性,提高反应后强度,相应增加喷煤量,进一步提高冶炼强度,增加高炉产量。     

Influence of the high content of Zh coal in coking batch on the coke quality

Industrial tests show that the enrichment of coal batch containing more than 70% Zh coal must be increased in order to boost coke strength. However, it makes more sense to replace some of the Zh coal in the batch with an optimal quantity of G coal, and to reduce the degree of crushing, so as to ensure coke quality consistent with blast-furnace requirements (minimum strength M ₂₅ = 90%, M ₁₀ = 6%).     

炼焦煤质量与焦炉加热制度对焦炭热性质的影响

随着高炉冶炼强度及喷煤比的不断提高,炼铁生产对焦炭质量提出了更高的要求。焦炭的反应性和反应后强度是考核焦炭质量的重要指标,影响焦炭反应性和反应后强度的因素很多,本文根据梅山的生产数据,从炼焦煤的质量和焦炉加热制度2个方面对焦炭反应性及反应后强度的影响进行了分析。     

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.