优化大冶竖炉球团焙烧工艺参数的试验研究

为了探索改善球团矿原料质量的途径,用润磨处理和未润磨处理精矿作原料的球团矿,按大冶竖炉球团矿生产的工艺条件在实验室进行了预热、焙烧等项目的试验。试验表明,在同样的预热、焙烧的工艺参数下,用润磨原料生产的球团矿,其抗压强度高于未润磨原料生产的球团矿;如按球团矿抗压强度达到3000N／个为基准,润磨原料比未润磨原料需要较少的预热时间、焙烧时间和较低的预热温度、焙烧温度。采用润磨技术处理精矿是改进竖炉球团矿生产的一项有效措施。     

天钢200万t链篦机-回转窑高硅球团矿生产实践

天钢炼铁厂200万t链篦机-回转窑球团生产线使用高硅磁铁矿和国内低品味赤铁矿,使成品球抗压强度受到影响。通过实验研究和生产实践,找出影响成品球抗压强度的主要影响因素。通过调整造球参数、采用薄料层快机速、提高预热和焙烧温度等途径,使成品球抗压强度稳定在2500～3200N/个,提高了成品球质量。     

马钢综合利用转炉污泥技术

主要介绍了在综合利用转炉炼钢污泥的过程中,马钢近年所开发的炼钢污泥管道输送工艺、制做冷固球团工艺和滚筒给料、对辊打碎炼钢污泥工艺,并对其中一些工艺的试验或工业应用效果进行了简要分析.     

Investigation of factors affecting pellet strength in straight grate induration machine

Abstract

During induration in a straight grate machine, the green pellets pass through four different thermal treatments, namely drying, preheating, heating and cooling. The pellet bed is fired with downdraught firing leading to thermal gradients through the bed. Corex sludge, which is used as fuel in the pellet mix, supplies the necessary energy for uniform heating of the pellet. The physicochemical conditions, e.g. the temperature and oxygen partial pressure mainly depend on the amount of fuel incorporated in the pellet mix. As a result the percentage and the distribution of various phases in the pellets vary, leading to deviation in quality. To study the distribution of phases and their impact on cold crushing strength at different carbon levels (1·20 and 1·35%), pellets from different layers of the induration bed in an industrial straight grate were characterised. It was observed that the strength of the pellets varied from 142 to 268 kg/pellet and 128 to 245 kg/pellet across bed, with carbon 1·20 and 1·35% respectively. It was found that middle layer pellets had higher strength compared to top and bottom layers. It was observed that amount of hematite, magnetite, porosity and the pore size plays a significant role on the pellet strength. Pellets with 1·20% carbon showed better physical and microstructural properties across the pellet bed compared to pellets with 1·35% carbon.     

冷压球团技术在高碳铬铁生产中的应用

重点介绍了不同铬粉矿采用冷压方式成球后,经过自然晾晒直接入炉,该方法对提高技术经济指标、降低生产成本起到了积极作用,并概述了影响冷压球团强度和质量的各种因素,以达到合理使用冷压球团矿的目的。     

马钢链箅机-回转窑氧化球团试验研究

基于马钢球团原料条件,在模拟试验装置中研究了链箅机-回转窑氧化球团生产的料层高度、鼓风干燥热风温度、抽风干燥热风温度、预热热风温度和回转窑焙烧等工艺参数。在配用40%(质量分数)赤铁精矿时,采用最佳链箅机-回转窑工艺参数条件下,获得了冶金性能良好的成品球团矿,主要指标为:单球抗压强度3 113 N,转鼓强度93.16%,抗磨指数2.00%,w(TFe)63.64%,w(FeO)1.62%。     

Al2O3细粉对MgO系浇注料性能的影响

本文研究了Al2O3细粉的加入对MgO系浇注料性能的影响。在110℃×24h烘干,1500℃×3h烧成制度下,通过改变基质中Al2O3细粉的加入量,对材料物理性能和力学性能进行测试。结果表明：3％～5％Al2O3细粉的加入能显著改善MgO系浇注料的综合烧结性能：显气孔率15％～17％;体积密度3．01～3．03g／cm^3;耐压强度和抗折强度分别高达85～92MPa和12．4—14．5MPa;当Al2O3细粉的加入量大于5％时,由于材料线变化率和显气孔率的过度增大,引起材料结构的松散,导致材料强度的降低和抗渣性能的下降如：显气孔率大于20％;体积密度小于2．90g／cm^3;耐压强度和抗折强度则分别小于70MPa和10MPa。     

Replacement of bentonite in hematite ore pelletisation using a combination of sodium lignosulphonate and copper smelting slag

Bentonite is the most common binder used in iron ore pelletisation owing to its good bonding properties in green and dry pellets at both ambient and elevated temperatures. However, due to its high alumina and silica content, it increases the slag volume and energy consumption in downstream processes. Organic binders may be used to replace bentonite; however, they fail to provide strength at a high temperature (700–900°C) due to poor thermal stability during pellet induration. In the present study, an organic binder Na lignosulphonate (NLS) has been used along with copper smelting slag (Cu-SS). FeO in Cu-SS provides diffusion bonding at high temperature and maintains the strength of pellets even after evaporation/burning of NLS. It also enhances recrystallisation bonding at relatively lower temperature to provide good strength. The study has been carried out with hematite ore and varying amounts of NLS and Cu-SS. Copper smelting slag (1.0%) addition with 0.5%NLS has been found to be optimum to provide very good green properties and ～300?kg/pellet cold crushing strength (CCS) at 1250°C induration temperature. However, hematite pellets of similar basicity with 0.5% bentonite requires higher induration temperature (1300°C) to achieve a similar CCS. The developed pellet also shows better reducibility (80%), similar reduction degradation index (18%) and swelling index (10%) to the usual bentonite pellet. Thus, the induration temperature of hematite pellet has been lowered by 50°C using a combination of NLS and Cu-SS eliminating bentonite completely, which can provide a considerable energy and cost saving.     

链箅机-回转窑直接还原的适宜焙烧温度

在实验室进行的链箅机—回转窑直接还原法的试验研究表明,还原产品的铁收得率与入窑球团的抗压强度、抗磨能力呈正相关关系;球团抗压强度及抗磨能力取决于链箅机焙烧温度。提高链箅机焙烧温度是提高链箅机—回转窑直接还原法的铁收得率和杜绝结圈的重要途径     

澳大利亚卡拉拉精矿造球性能的研究

通过对卡拉拉精矿一系列的基础检测,包括各精矿的同化温度、流动性指数、连晶强度、黏结相强度,以及与鞍钢自产精矿的生球的落下强度、成球率、抗压强度和成品球的抗压强度、膨胀率的对比试验,证明卡拉拉精矿的各种性能与鞍钢自产精矿性能接近,所以卡拉拉精矿能够满足鞍钢球团生产的需要。     

MgO对球团矿质量的影响

通过对临钢两种磁铁精矿球团焙烧及冶金性能研究表明，在最佳试验条件下，MgO含量在2．8％（塔儿山矿60％）以下时，球团矿抗压强度能达到2000N／个。并且随着MgO含量增加，球团矿抗压强度下降，而冶金性能得到改善。     

链篦机—回转窑直接还原的适宜焙烧温度

在实验室进行了链篦机－回转窑直接还原的试验研究。结果表明：还原产品的铁收率得与入窑球团的抗压强度、抗磨能力正相关关系;球团抗压强度及抗磨能力取决于链篦机的焙烧温度。提高链篦机焙烧温度是提高链篦机－回转窑直接还原法铁假得率和杜绝结的重要途径。     

球团返矿二次利用新途径

为了合理利用济钢球团厂的球团返矿,根据球团返矿的特性,进行了冷固结压团试验研究,以寻求适合压团的原料粒度组成及添加剂.试验结果表明:将球团返矿破碎至小于4mm的粒级,另配加部分铁精矿进行压团,同时配加两种不同的添加剂,压球的强度和铁品位都达到了较理想的指标.     

高硅镁质熔剂性球团成球过程及冷态性能实验

生球质量的好坏是直接关系到企业是否顺利生产高质量熔剂性球团的前提。为探明SiO2、碱度及MgO含量对生球性能的影响规律,以唐钢生产所用3种磁铁矿为原料,通过添加生石灰调节碱度,添加白云石调节MgO含量,配比3种铁矿粉调节SiO2含量,进行了造球及生球冷态性能的试验。研究发现,无论是改变SiO2、碱度还是MgO含量,其生球适宜水分基本都保持在8%~9%(质量分数)之间。生球的成球率维持在90%以上,成球率良好。生球的抗压强度、落下强度的大小以及爆裂温度的高低,主要受铁矿粉及熔剂的粒度组成、物理性能以及生球适宜水分大小的影响。     

大掺量高钛型高炉渣实心砖的研制

首次将支持向量机算法应用于优化胶凝材料的组成,建立了胶凝材料组成与28 d耐压强度的数学模型,并成功应用于实践,试制出高钛高炉渣掺量达80%以上的MU15矿渣实心砖,为攀钢高钛型高炉渣利用提供一条新的途径.数学模型的建立也为今后高钛型高炉渣生产矿渣砖提供一条新的材料设计途径.     

Strength and high temperature behaviour of carbon composite pellets containing BOF fine dust

Abstract

Steel plants produce significant amounts of dust and sludge during iron and steel production. These wastes contain valuable elements, such as Fe, Cr, Ni, C, K and Na and should be handled properly to prevent them from polluting the environment. In order to utilise the BOF fine dust, the effects of the dust on cold bonded pelletising, solid state reduction and reduction melting behaviours of composite pellets made from iron ore and anthracite with added BOF fine dust were investigated at laboratory scale. The BOF dust was found to improve the cold compressive strength of the wet green carbon composite pellet, and increased with increasing dust content. Almost four times the amount of dust was needed to get the same effect on the strength of the pellet when it was used to replace bentonite. The carbothermic reduction of the composite pellet proceeded effectively at temperatures above 1200°C. The BOF dust had a positive effect on the reduction rate of the pellet, and the rate increased with increased dust content. The reduction of iron oxide was topochemical and conformed to a shrinking core kinetic model. The dust was found to improve the iron and slag melting separation rate of reduced pellets at 1400°C when its content was less than 23·11 wt-%. The liquidus temperature of the slag would decrease with the content of BOF dust increasing from zero to ～30 wt-% and then increase if the content continued to become more in the experiment. Utilising the BOF dust as the binder and flux to adjust the composition of the slag system can potentially reduce the slag ratio and production cost compared with using bentonite and limestone. This work can help to find a new process for the effective utilisation of BOF dust in a more appropriate and environmentally friendly way.     

Influence of raw material particle size on quality of pellets

Abstract

Pellet plant (4·2 MPta capacity) of JSW Steel Ltd imports iron ore fines from different mines to produce pellets for its Corex and Blast Furnace plants. The pelletisation process involves drying the ore fines to reduce the moisture content to less than 1%, grinding in open circuit ball mills to get required fineness. To produce good quality of pellets certain additives are important and limestone is employed for modifying the pellet basicity. Iron ore fines of ?10 mm size and limestone are ground together in a ball mill to get sufficient fineness for the balling process. However, as limestone is harder than iron ore fines the + 100 mesh size limestone particles is higher than required and not all the limestone is fully consumed in the reaction for melt formation. Microstructural studies were conducted under a Leica DMRX polarized microscope at different level fineness (?325# ? 56, 58 and 60%) to investigate its effect on the pellet quality. The cold crushing strength of the pellet improved from 203 to 220 kg p^?1 with increase in fineness. With increase in percentage of ?325# particle size in the ground product RDI of the pellet decreased from 13·8 to 11·9% with increased melt formation from 5 to 9%. With increase in fineness ?325# from 56 to 60% the 150 to 500 μm size pores decreased from 51·8 to 13·6%.     

二元铁酸钙还原行为的研究

实验在合成CF2，CF、C2F的基础上，利用热台显微镜动态地观察了二元铁酸钙还原过程中的显微结构变化，考察了它们的还原性，还原前后的强度变化，结果表明C2F，CF．CF2还原性依次增强；CF2的抗压强度在还原度较低时有明显的下降，在还原度较高时随还原度的增加抗压强度增加；CF与C2F的抗压强度随还原度的提高而提高；CF2在还原过程中有明显的裂纹产生，裂纹的产生影响了CF2的强度。     

冷固球团矿热态强度变化规律的研究

西方研究了几种铁精球团矿在煤基回转窑直接还原过程中热态强度变化规律。结果表明：添加“复合粘结剂”铁精矿冷固球团矿在还原过程中抗压强度下降幅度和强度低谷区宽度上于预热球团矿，水泥冷固球团矿和氧化才矿，其热态强度能满足工业生产加转窑的要求，适于做回转窑直接还原炉料。     

优化球团原料的配矿

为了获得低成本、质量好的球团矿产品,以两种铁精矿粉（低铁高硅磁铁矿和高铁低硅磁铁矿）和一种膨润土为原料,以生球落下强度、抗压强度以及焙烧后成品球团抗压强度为评价指标,在相同造球工艺和膨润土加入量的条件下,研究两种质量不同的铁精矿混合配料造球对球团性能的影响。研究表明,随着低铁高硅矿配比的增加,生球落下强度、抗压强度以及焙烧后成品球团抗压强度均随之降低。通过优化配矿,当低铁高硅矿配比达40%时,生球的落下强度达到3次以上,抗压强度达20N以上,焙烧后抗压强度为3850N,完全满足生产要求。