Influence of Coating Granulation Process on Iron Ore Sinter Quality and Productivity

For better blast furnace performance, there has always been a need for better quality raw materials like sinter, lump ore, and pellets. Among these raw materials the usage of sinter in blast furnace is at higher side compared to other iron bearing materials. As the quality of sinter product improves, its usage in blast furnaces also increases. Iron ore fines are the main source for sinter making. To improve the sinter properties it is necessary to provide good quality of iron ore fines. Due to depletion of high grade iron ore resources, goethite and limonitic ore content in iron ore fines is expected to increase gradually. Usually limonitic and goethite ore are associated with higher alumina and LOI. The conventional sintering process is one of the well established processes for high quality hematite ore. It does not fully respond to the low grade iron ore associated with goethite and limonite. This has led to deterioration in sinter properties and productivity. In recent years the improvement in the quasi‐particle structure with the granulation process is an effective method for improving sinter quality and productivity. To improve the sinter quality and productivity for low grade iron ore fines, different granulation processes like the conventional one, and other two advanced granulation processes like coke breeze, and flux & coke breeze coating granulation were studied in detail by conducting laboratory pot grate sintering experiments. From the test results it was found that sinter productivity, physical and metallurgical properties of the sinter improved with flux & coke breeze coating granulation process compared to conventional and coke breeze coating granulation process. Proper selection of the granulation time is very important to achieve the desired sinter properties. In the present work detailed laboratory experiments have been carried out by varying the coating time from 30s to 110s to study the influence of flux & coke breeze coating granulation time on mineralogy, productivity, physical, and metallurgical properties of sinter. With a coating granulation time of 50s, higher productivity, higher yield, and stronger sinter (higher T.I) with lower RDI and ‐5mm size sinter were achieved.     

钢铁企业烧结制粒工艺与设备优化进展及趋势

 为明晰当前烧结制粒工艺的发展进展及未来发展的趋势,对钢铁企业烧结制粒工艺与设备进行了充分的总结与分析。烧结制粒性能直接影响着料层透气性以及准颗粒结构分布,是钢铁企业烧结工序中重要的环节,长期以来铁矿石烧结工序的热态性能受到较多关注,但制粒性能欠缺重视。近年来,随着理论和工艺的发展,烧结制粒受到钢铁企业越来越多的重视,随之针对制粒也采取了诸多工艺与设备的优化措施。首先阐述了烧结制粒优化的意义,进而总结了近些年来国内外钢铁企业在原料预处理、滚筒设备、生石灰消化以及混合料水分监测4个方面针对制粒做出的优化进展,并基于对烧结制粒的理解和新兴人工智能技术的认识展望了在可预见的未来钢铁企业烧结制粒优化的趋势。     

强力混合强化微细粒精矿烧结的工艺试验分析

为了研究强力混合工艺对微细粒精矿粉烧结的作用,针对太钢微细粒精矿为主的烧结原料结构,系统开展了强力混合对制粒效果、烧结指标影响的研究。结果表明,与传统圆筒混合、制粒工艺相比,强力混合因强化了水分的分散和物料混匀,适宜制粒水分明显降低,混合料制粒效果明显改善,制粒强度提升,有利于减少粉尘排放量。对于太钢原料结构而言,适宜的强力混合-制粒工艺流程为圆筒混合+强力混合+圆筒制粒,烧结速度和利用系数大幅提升,烧结效果得到改善。     

铁矿粉颗粒特性对其烧结制粒性的影响

 掌握铁矿粉的烧结制粒性是进行制粒工艺参数优化以保证混匀矿优良制粒效果的基础,确定铁矿粉颗粒特性对其制粒性的影响,是值得深入研究的工艺理论问题。通过微型圆筒制粒法研究铁矿粉的圆形度[（Ψw）]、气孔率[（P）]、润湿性[(cosθ)]以及粒度分布对其制粒性的影响,在此基础上,采用回归方法预测混匀矿的制粒性。结果表明,铁矿粉的圆形度和气孔率对其制粒性有负面影响,而提高润湿性则有利于铁矿粉制粒;铁矿粉粗颗粒群的制粒性与其等效表面积呈反比,细颗粒群的制粒性与其黏附粉与中间粒级的比值[(R<0.25 mm/0.25～1.00 mm)]呈正比;混匀矿的制粒性可以根据各组元的配比和颗粒特性进行有效预测。     

Influence of nature and particle size distribution on granulation of iron ore mixtures used in a sinter strand

Abstract

The ore mixture granulation process is described and the granulation fitness of a series of iron ores forming part of the mixture is studied. Good granulation and control of the maximum sintering temperature makes it possible to achieve the optimum sinter structure, formed by a hematite nucleus surrounded by a lattice of acicular ferrites. The granulation fitness of ore mixtures used to manufacture a series of sinters in a pilot plant are also determined. It is verified that sinters with an optimum structure have been obtained. A series of iron ores are classified using the granulation index (G index). The evolution of the G index of ore mixtures used in ACERALIA during recent years is considered and it is verified how improvement of the G index increases productivity and decreases coke consumption in the sinter strand.     

Influence of Alumina on Iron Ore Sinter Properties and Productivity in the Conventional and Selective Granulation Sintering Process

Iron ore sinter constitutes a major proportion of blast furnace burden. Hence, its quality and consistency have a significant impact on blast furnace performance. Iron ore fines are the main source for sinter, and the chemical composition of the iron ore fines, together with the thermal conditions that blends are subjected to, plays an important role in forming the primary melt during the sintering process and accordingly determines the sinter structure and quality. Therefore, considerable importance has been placed on the chemical composition and consistency of iron ore fines, particularly in terms of alumina content. Due to depletion of high grade iron ore resources, alumina content in the iron ore fines is expected to increase gradually. Ore with higher alumina content is usually expected to be detrimental in forming the sinter matrix, if sintered alone, due to the low reactivity of alumina bearing minerals and the high viscosity of primary melts. The selective granulation process is a new sintering process for high alumina iron ore fines, and can eliminate the adverse effects of ‘hard to sinter’ or ‘unsuitable – for ironmaking’ ores. In the present work laboratory sintering experiments have been carried out with iron ore fines of different alumina level (2.00 to 5.46 mass‐%) to know the influence of alumina on mineralogy, productivity, physical and metallurgical properties of sinter prepared by the conventional and the selective granulation process. With increasing alumina content in sinter of both the conventional and selective granulation process, the fractions of hematite and of silico‐ferrites of calcium and alumina (SFCA) as well as the pore phase increased whereas the magnetite and silicate phases decreased. With increase in alumina content sinter productivity and tumbler index (T.I.) decreased, and metallurgical properties like sinter RDI and reducibility improved. However, sinter of the selective granulation process showed better results compared to the conventional process.     

烧结制粒工艺研究进展

阐述了各种烧结制粒工艺及其发展,并对各制粒工艺进行了比较,重点阐述了基于原料性质的分层制粒工艺。应用传统的烧结制粒工艺处理多孔铁矿石,烧结利用系数、烧结矿冷强度和还原性都下降。而试验应用基于原料性质的分层制粒工艺,不但可以减少烧结矿过熔,而且液相流动性也得到改善,烧结料层的透气性增加,烧结利用系数及烧结矿的强度明显提高。     

高比例精矿粉对烧结的影响分析及强化措施探讨

太钢吕梁铁矿投产,烧结铁料中自产铁矿的配比超过了85%,且自产铁精矿粒度很细,其中吕梁铁精矿不超过0.045mm的比例占到了96%以上。要在730mm左右的料层高度条件下,为4350m3高炉生产优质烧结矿,难度较大。会使混合料制粒效果变差,而且自产精粉比例较大,配矿结构调整余地很小,不利于烧结过程的进行和烧结矿质量的改善。为了给烧结配用自产资源提供技术支持,摸清高比例精矿粉对烧结造成的影响,在技术中心进行了烧结杯试验。试验结果表明：随着精粉率的提高,烧结矿的产、质量指标变差,当精粉率超过70%时,烧结过程变得缓慢,特别是全精粉烧结时,控制不好,会出现烧结熄火,烧结过程停滞的现象。为此,要采取强化制粒、优化燃料粒度、提高碱度等有效措施。     

铁矿粉烧结制粒过程颗粒行为研究综述

摘要：烧结原料需经过制粒处理以确保高效低耗的烧结生产,即在水或其他粘结剂的参与下混合料颗粒在相互运动、碰撞中形成粒度更大且粒度分布更窄的聚团颗粒体。制粒效果受制粒设备参数和铁矿粉物理化学性质的影响,因而合适的制粒工艺和铁矿粉优化配置对烧结技术经济指标的改善具有显著作用。阐述了制粒现象的基本理论,综述了制粒过程中颗粒聚结长大的作用力以及颗粒的长大机制,制粒工艺参数如加水量、搅拌动能、制粒时间等和铁矿石的粒度组成、表面性质、颗粒形貌等性质对制粒效果的影响规律。相关结果为系统深入理解铁矿粉制粒过程以及高效生产优质准颗粒提供理论基础。     

铁矿石高温烧结基础特性评价方法的国外研究进展

 随着全球优质铁矿石日益减少、资源禀赋变差,国内外钢厂普遍面临着烧结原料供应不稳定、铁矿石性质波动大、原料结构频繁变化等问题,对烧结生产、高炉冶炼和产品质量产生了极大的不利影响。因此,开展铁矿石烧结性能评价研究具有重要的现实意义。铁矿石烧结基础特性可分为冷态特性和高温特性两大类,前者主要包括铁矿石的化学成分、粒度组成、矿物学特性等常温性质,后者主要包括铁矿石的同化性能、液相生成特性等高温成矿行为及实际烧结性能。概述了国外关于铁矿石高温烧结基础特性评价方法的研究进展,系统归纳了不同研究机构提出的评价指标和试验方法。已有研究表明,现有基于团块烧结法的评价方法虽然对铁矿石不同的烧结行为分别进行了深入研究,但未能在其与铁矿石的实际烧结性能之间建立起准确可靠的关系,主要原因在于,对影响铁矿石实际烧结性能的最关键因素把握不准,同时对烧结过程的模拟性有待提高。因此,揭示铁矿石基础特性与其烧结性能的内在联系,首要前提在于必须深入研究和把握“铁矿石-制粒物料-烧结矿”不同阶段物料性质的传递规律,查明影响铁矿粉烧结过程的主要因素,这对找准高温烧结基础特性研究的切入点具有十分重要的意义。     

赤铁精粉烧结技术的研究

从物理、化学和表面特性上分析了赤铁精粉的烧结特点,提出了赤铁精粉烧结适宜的粘结相是多元铁酸钙,相适应的烧结条件是低温、高碱度和氧化性气氛,结合对铁矿石烧结过程的研究,给出与赤铁精粉的烧结相适宜的烧结技术：优化混合料粒度分布,强化造粒,改善料层透气性;优化燃料在烧结料层内分布,提高完全燃烧比例,充分利用有效热量;选择适宜的粘结相量;利用烧结添加剂获得合理矿相结构;采用厚料层操作,充分利用燃烧热量,降低烧结固体燃耗等。     

New method to determine optimum water content for iron ore granulation

Abstract

Granulation is necessary before iron ore sintering. The optimum granulation moisture added to the mixture of iron ores, fuel and coke for obtaining suitable size distribution of the granules after tumbled in a drum is of vital importance for the sintering. In order to investigate the optimum moisture content, the moisture capacity of the iron ore, which means the maximum water content held in iron ores of unit mass, is defined and measured in a self-designed apparatus. The relationship between the moisture capacity and some other characteristics of iron ores, which include mineral and chemical composition, size distribution and mineralogy, is discussed. It was found that the mineral composition and the size distribution of the iron ore particles greatly influence the moisture capacity of the iron ores. The moisture capacity of the iron ore was also applied to optimise the granulation by finding the relationship between the moisture capacity of the mixture and the optimum water content. The moisture capacity has positive correlation with the optimum water content. The iron ore, which has high moisture capacity, needs more water added in the granulation process in order to get high permeability. The correlation was given to predict the optimum water content in the granulation based on the moisture capacity measurement.     

基于生石灰吸水性的适宜烧结制粒水分

为了有效发挥生石灰在制粒过程的作用,依据生石灰的吸水特性对烧结料制粒水分进行优化,是值得深入研究的工艺技术问题。考察了固定量配水、满足生石灰完全消化的配水,以及满足生石灰湿容量的配水等3种加水量选取方式,对烧结混合料制粒效果的影响。研究结果表明:烧结制粒过程中生石灰的吸水,一方面消耗于生成Ca(OH)2的化合水,另一方面还包括生石灰消化后自身吸收的物理水,二者影响烧结料的水分含量及分布;当制粒水分满足化合水消耗时,虽然烧结料水分得以保证,但消石灰和CaCO3吸水会争夺铁矿粉中的水分而影响制粒效果;当制粒水分满足生石灰湿容量时,可获得适宜烧结制粒水分,使铁矿粉中的水分得以保证,生石灰改善制粒的作用充分发挥。     

Improvement of sintering characteristics by selective granulation of high Al2O3 iron ores and ultrafine iron ores

The worldwide steel companies are expected to use low grade iron ores such as pisolitic iron ores, high Al₂O₃ iron ores and ultrafine iron ores etc. in their sinter blends due to the depletion of high grade iron ores or for the economic reason. This study investigated the methods for improving sintering characteristics without deteriorating sintering productivity and sinter quality by blending mini-pellets comprising high Al₂O₃ pisolitic iron ores and ultrafine iron ores containing low alumina. The results showed that the blending of iron ore mini-pellets produced by selective granulation is an effective way to improve sintering productivity and sinter quality without increasing the Al₂O₃ content in sinter as well as to effectively utilise high Al₂O₃ iron ores and ultrafine iron ores in the sintering process.     

氧化物料制粒技术在ISP烧结工艺中的应用研究

分析了氧化物料直接返回烧结配料的不良影响,介绍了韶关冶炼厂将氧化物料通过制粒应用在生产中,并逐步提升制粒颗粒在烧结配料中的占比,调整烧结过程的工艺参数,逐步改善烧结过程中物料流转状态,使烧结块的产能和电尘的产出逐步形成一种良性的平衡的应用实践。此技术的实施应用有效地提升了烧结车间的烧结块产能,降低ISP工艺原料成本,提升ISP工艺的经济效益和社会效益。     

用小球团烧结法生产高碱度烧结矿的经验

总结了安钢集团水冶钢铁公司采用小球团烧结法生产高碱度烧结矿九年来取得的经验。其经验如下：1)宜采用厚料层低温烧结和热风烧结技术；2)强化混合料制粒是小球团烧结工艺的核心；3)实行均匀烧结、保持烧结矿较高的成品率是烧结生产稳定高效的关键。     

Present situation and development of saving energy and reducing emission technology in iron ore sintering process

The energy consumption of iron ore sintering process is about 10%- 15%of the total of iron and steel industry.Therefore,it is of great significance to take effective measures to reduce the energy consumption in the iron ore sintering process to reduce the costs of sintering product and cut down the emissions of harmful gases,such as CO₂ and SO₂.In this study,the technology development of saving energy and reducing emission in iron ore sintering process was reviewed and discussed;some new directions and measures of saving energy were presented for the sintering process in the future.     

Preparation of blast furnace burdens with middle-low basicity from high-SiO2-content iron concentrates by composite agglomeration process (CAP)

With the depletion of high-grade iron ores, iron and steel companies all over the world are expected to use refractory iron ore resources in the sintering process. Composite agglomeration process (CAP) was utilised to improve the sintering performances of high-SiO₂-content iron concentrates in this study. Theoretical calculation indicates that CAP is more effective for the agglomeration of high-SiO₂-content iron concentrates compared with traditional sintering process (TSP). The sintering pot tests results showed that the sintering yield of 74.15 wt-%, tumbler index of 72.75 wt-% and productivity of 1.54 t·(m²·h)^?1 were achieved, which is 9.12 wt-%, 10.70 wt-% and 0.45 t·(m²·h)^?1 higher than that by TSP, respectively. Moreover, CAP decreased the solid fuel consumption by 11.77 kgfuel/tproduct. Researches of metallurgical performances showed the CAP product can be used as high-quality blast furnace burdens. This investigation provides an effective route to utilise the inferior high-SiO₂-content iron concentrates.     

酸性物料的粒度对承钢分流制粒厚料层烧结的影响

研究了承钢分流制粒厚料层酸性物料粒度对烧结工艺的影响。大粒度物料能改善料层的透气性,有利于厚料层的应用。酸性物料的粒度较大时,矿相里有大量集中分布的赤铁矿,局部形成交织熔蚀结构,能极大的改善钒钛磁铁矿的冶金性能。     

Improvement of sintering performance of sinter mixtures containing high ratio of specularite fines

Although specularite fines possess high iron grade and low impurities, their granulation performance was poor so that the ratio of specularite fines is kept below 20% in sinter ore blends because of low permeability and productivity and weak strength. In order to increase its ratio in sintering, binders were used to improve the granulation performance of sinter blends containing high ratio of specularite fines in sintering pot test. Results show that cold permeability of the sintering bed increases by 19. 05% by adding 0. 65mass% bentonite or by 27. 98% by 0. 55mass% BF composite binder respectively when 36 mass% specularite fines are proportioned in sinter blends. In addition, the hot permeability is also improved by adding bentonite or BF composite binder, respectively, resulting in an increase in the productivity of 11. 67% and 7. 50% as well as an decrease in solid fuel consumption of 2. 82kg/t and 4. 01kg/t, respectively, while the tumble index, chemical composition and metallurgical performance meet the requirement of blast furnace. So using suitable binders is one of effective ways to improve the granulation and sintering performance of sinter ore blends comprising high ratio of specularite fines.