Ensuring stable coke properties

Information is presented regarding the coal used for coke production in 2010. At least four problems must be addressed in order to ensure stable coke properties. The first three are associated with exhaustive information regarding the coal batch, the stability of its properties, and the uniformity of the coal supplied to the enterprise. The fourth is associated with the method of calculating coal batch of specified quality and properties. An approach to the fourth problem is proposed.     

European quality requirements on blast-furnace coke

European quality requirements on blast-furnace coke are compared with the quality of coke produced in various countries. Close internal and external pair relations are observed: between M ₄₀ and M ₁₀, CSR and CRI, M ₄₀ and CSR, M ₄₀ and CRI, M ₁₀ and CSR, and M ₁₀ and CRI.     

Changes in granulometric composition of blast-furnace coke

The basic requirements on the granulometric composition of blast-furnace coke are considered. The change in granulometric composition over time is considered for the example of Krivoi Rog coke plant (now the coke-production facility at PAT ArcelorMittal Krivoi Rog). Recently, the size classes in the gross coke produced have been redistributed, with increase in the content of the >80 mm, <25 mm, and 80–60 mm classes; coke quality (in terms of the strength M ₂₅ and ease of wear M ₁₀) has also declined. To obtain more uniform granulometric composition, consistent mechanical treatment of the coke is required.     

New insights into the reactivity of blast-furnace coke

The factors most responsible for the reactivity of metallurgical coke—the structure of the carbon matrix and the catalytic action of the inorganic components—are considered in the light of new data regarding the relation between CRI and the anisotropy of the reflectance ΔR _o and data regarding the variable composition of the mineral components during the high-temperature reaction of CO₂ with coke. New literature data regarding the transformations of coke samples within special metal baskets in a prototype blast furnace are also discussed.     

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.     

Gasification of a blast-furnace coke. A study using scanning electron microscopy

Metallurgical coke (3 mm size) was gasified to controlled burn-offs in carbon dioxide and oxygen at 920 and 1200 °C. Changes of surface topography were monitored using scanning electron microscopy. Gasification proceeded not by a process of smooth surface ablation, but instead, surface pitting and fissure formation occurred. Increasing temperature apparently encouraged fissuring. The surface pitting may occur at positions of catalytically active impurities. Such modes of gasification could increase the proportion of fines in a blast furnace because of decreased abrasion resistance of a pitted surface and of decreased strength of fissured coke pieces.     

Methods of determining coke quality

Methods of determining coke quality are compared.     

焦炭质量预测方法的应用

以太原煤炭气化(集团)有限责任公司的工业焦炉数据为基础,建立了该公司的焦炭质量预测模型。利用单种煤和配合煤的各种性质指标预测焦炭质量,并指导配煤,以获得稳定的焦炭质量。     

Processes for boosting coke quality

The temperature stress in coke pieces of different sizes is calculated during cooling by sprayed water. In the range 650–200°C, no cracks are formed if the cooling time is more than 13 min. The benefits of the new cooling method are outlined. Examples of industrial-drum application are presented. In coke production, drums may provide great benefits.     

影响焦炭质量的因素分析

焦炭的质量主要取决于配合煤性质和工艺条件。配合煤的性质主要是结焦性、煤的粘结性对焦炭强度的影响较大;炼焦煤的性质影响焦炭的灰分、硫分等化学组成,影响焦炭强度。炼焦的工艺条件是水分、灰分、细度、堆密度等;结焦时间影响焦炭冷态、热态性能和显微特性。     

Enhancing coke quality in dry slaking

Improvement in coke strength by methane treatment in dry quenching is considered. Kinetic and thermodynamic data for the thermal decomposition of methane indicate that its decomposition products may participate in a secondary reaction: the crosslinking of graphite planes in the coke structure, with consequent increase in strength. Laboratory tests confirm this conclusion. The proposed method may be used at coke plants to improve coke strength.     

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%.     

Plastic wastes, lube oils and carbochemical products as secondary feedstocks for blast-furnace coke production

Two plastic wastes (polyolefin-enriched and multicomponent), two lube oils (paraffinic and synthetic) and one coal-tar were assessed as individual and combined additives to coal blends for the production of blast furnace coke. The effects of adding 2 wt.% of these additives or their mixtures (50:50 w/w) on the coking capacity of coal, coking pressure and coke quality parameters were investigated. It was found that the two plastic wastes reduce fluidity, whereas the addition of oils and tar helps to partially restore the fluidity of the coal-plastic blend. From the co-carbonization of the coking blend with the different wastes in a movable wall oven of over 15 kg capacity, it was deduced that polyolefins have a detrimental effect on coking pressure. The addition of oils and tar to the coal-plastic blend has different modifying effects. Whereas paraffinic oil eliminated the high coking pressure caused by the polyolefins, polyol-ester oil had a weak reducing effect unlike coal-tar which had a strong enhancing effect. The compatibility of the oils/tar with plastics and coal and the beneficial influence of these combinations on coking pressure is discussed in relation to the miscibility of the plastic and the oily and bituminous additives, and the amount and composition of the volatile matter evolved from each additive during pyrolysis as evaluated by thermal analysis. Furthermore, it was found that coke reactivity towards CO₂ (CRI) and coke strength after reaction with CO₂ (CSR) are heavily dependent on the composition of the plastic waste, with polystyrene (PS) and polyethylene terephthalate (PET) having a clear negative effect. The porosity of the cokes obtained from blends containing plastic wastes is always higher, but the pores are smaller in size.     

捣固炼焦对焦炭质量的影响

利用40kg试验焦炉进行顶装与捣固炼焦试验,对比分析发现,捣固炼焦工艺可以明显改善焦炭的冷态强度,提高焦炭抗碎强度,改善耐磨强度,还可提高焦炭的反应后强度,但对焦炭的反应性影响不大,可以使焦炭粒度组成更加均匀化。     

焦炭塔内温度场分布对生成针状焦质量的影响

正近年来随着针状焦生产技术研究的深入,对针状焦形成机理有了进一步认识和理解。工业生产装置的操作水平也在逐步提高,工艺技术控制水平日臻成熟。针焦产品广泛使用,产品质量提升速度也在加快,尤其是在形成针状焦重要环节延迟焦化工序的生产技术研究,有了积极改进和提高。本文根据中钢集团鞍山热能研究院多年来生产针焦所得经验,探讨焦炭塔内温度场分布对生成针焦质量的影响。     

焦炭质量的多参数预测与调控

开展配煤炼焦试验研究,在原传统经验型配煤调控质量指标体系的基础上,增加新的指标参数。预测调控焦炭质量。介绍了多参数预测调控在实际应用中所发挥的作用,通过增加新指标,保障了焦炭强度的稳定．满足了炼铁高炉不同阶段和状态下对焦炭质量的要求。     

选择性破碎对焦炭质量的改善

介绍了煤粒度对焦炭质量的影响,试验对熔融性差的大庄煤进行了粒级及配入比例的研究,经分析,确定了合适的煤料粒度及最佳的配煤方案,从而达到改善焦炭质量,降低配煤成本的目的。     

Uniformity of coal batch and coke quality

Improving the mixing of batch components in the charge significantly improves their wear resistance but does not affect the crushability, on account of the different disintegration processes of the coke pieces.     

鞍钢鲅鱼圈7m焦炉焦炭质量评述

鞍钢鲅鱼圈7m焦炉是国内首座开工建设的大型化焦炉,经过1年多的运行,现焦炉运行稳定,焦炭各项质量指标均达到国内焦化行业的先进水平,其焦炭强度指标很好地满足了4000m,大容积高炉的生产要求。文中详述了7m焦炉投产后配煤的优化管理、改善焦炭质量以及保证干熄焦稳定运行的一系列措施。