有机复合粘结剂特性表征及对球团矿性能的影响

摘要：添加有机粘结剂代替部分膨润土是减少成品球团矿的脉石含量的有效途径之一。通过残烧实验和XRD研究了膨润土与有机粘结剂间的相互作用,结果表明有机复合粘结剂比原始膨润土的晶层间距增加了008 nm。造球和焙烧实验结果表明,添加有机粘结剂替代膨润土可以提高生球落下和抗压强度。气基还原实验结果表明,添加有机粘结剂替代05%（质量分数）膨润土可以提高球团矿还原性,还原粘接指数也同时升高。SEM显微结果表明,添加有机复合粘结剂可以提高球团矿的孔隙率,有利于还原气体进入球团矿内部,从而改善球团矿的还原性。为制备有机复合粘结剂球团矿提供了参考,有助于扩大有机复合粘结剂在炼铁中的应用。     

包钢球团配加复合粘结剂替代膨润土研究

文章针对包钢球团膨润土配比高、球团矿SiO_2含量高的生产状况,提出使用复合粘结剂替代膨润土的技术方案,并进行了试验研究。结果表明:使用8#复合粘结剂可提高球团矿品位0.84个百分点,降低SiO_2含量0.86个百分点,能更好的满足高炉冶炼需求。     

在铁矿球团矿生产中膨润土聚合物复合粘结剂的应用前景

从冶金学意义上研究了粘结材料应用的演化——从膨润土到膨润土聚合物复合粘结剂。根据最近的实验室研究、工业试验研究和大规模工业试验研究,表明了膨润土聚合物复合粘结剂在球团矿生产中具有提高冶金性能的独特效果。该粘结剂的选择原则考虑到了铁精矿的组成特性和自身特性。研究表明,俄罗斯生产厂（莫斯科市的“膨润土”公司）对该种粘结剂的应用效果要优于高价进口的类似材料（Floform）。     

鞍钢球团矿添加镁质复合粘结剂的研究

为改善球团矿高温冶金性能,用镁质复合粘结剂代替传统粘结剂膨润土进行造球、氧化焙烧、冶金性能等试验研究。试验结果表明,随着镁质复合粘结剂逐渐增加,生球强度、TFe含量、成品球团抗压强度等技术指标有所降低,但仍高于生产技术指标要求,球团矿冶金性能得到改善,还原膨胀率由16.7%降低到13.1%,初始软化温度和滴落温度提高。     

球团矿粘结剂的最佳选择

为了降低球团膨润土用量 ,进行了几种膨润土、有机粘结剂及有机 /无机复合粘结剂的造球试验 ,试验结果表明 :在本钢现有条件下 ,选择合适比例的钠基膨润土和有机粘结剂生产的球团矿能满足高炉冶炼要求 ,但复合粘结剂效果最好     

添加复合粘结剂的球团试验

对复合粘结剂与无机膨润土粘结剂进行了球团对比试验。试验结果表明，复合粘结剂的成球性能远远优于无机膨润土的，可大幅度降低粘结剂配比(由2．5％降低至0．6％～1．0％)，提高球团矿品位(球团矿品位上升0．8％～1．0％)。配加复合粘结剂的生球爆裂温度和成品球强度指标均有下降，但这些指标都能满足球团生产和高炉冶炼要求。     

铁精矿冷固球团矿煤基回转窑直接还原新工艺

铁精矿冷固球团矿煤基回转窑直接还原新工艺的关键技术包括复合粘结剂及相应的配套实用技术,提出了含复合粘结剂的生球强度界面作用力综合模型,冷固球团矿强度的粘结膜机理,含复合粘结剂的冷固球团矿催化还原体积反应机制及全窑高温快速还原热工制度。     

润磨预处理对改善MgO球团矿预热焙烧性能的影响

 通过在铁精矿粉中配加镁质粘结剂进行了生产镁质球团矿的试验研究。研究结果表明,与酸性球团矿相比,配加镁质粘结剂生产MgO球团矿时所需要的预热温度和焙烧温度均较高,且焙烧时间也较长。但对铁精矿和镁质粘结剂混匀进行润磨预处理能改善MgO球团矿预热焙烧性能。混合料经润磨预处理后,球团矿预热温度能降低80℃,焙烧温度至少能降低30℃,焙烧时间至少能缩短4min。     

济钢球团配加碱性复合粘结剂试验

济钢在球团膨润土中配加碱性物料,采用雷蒙磨细磨,试验成功了低SiO2含量、造球粘结性能良好的碱性复合球用用粘结剂,取代以SiO2含量为主的膨润土类粘结剂。工业试验结果表明,配加该碱性复合粘结剂,提高了球团矿品位,改善了球团矿冶金性能,经济效益显著。     

低成本球团矿原料的合理配置

基于现代创新理论开创者Joseph Schumpeter的创新理论,根据包钢炼铁厂球团矿生产可用铁精矿和粘结剂种类相对较多的生产实际,充分利用各种铁精矿资源以及粘结剂的特性,开辟和利用新的原材料,通过合理配置各种资源,实现资源配置的合理优化,降低了球团矿生产成本,并改善了球团矿质量.     

Humic Substance-based Binder In Iron Ore Pelletization: A Review

Due to the reducing ability and bonding effect, a humic substance-based binder has been added into iron ore pellets, both as a reductant and a binder. However, humic substance-based binders were not commonly used in pelletization since some pelletizing results indicated they were not as good asbentonite or other binders. Thus, there were few detailed investigations using humic substance-based binders in pelletization before the 1980s. Funa, which is a type of humic substance-based binder extracted from lignite, was successfully invented and applied in cold-bonded pellets in China. Since the organic fraction in the humic substance-based binder is burnt away during heating, leaving no contaminant in pellets and improving the iron content of the pellets, humic substance-based binders were also gradually utilized in oxidized pellets. On the basis of Funa binder research, the extracting procedure of a humic substance-based binder was modified, and a composite binder named Modified Humic Acid (MHA)was prepared for oxidized pellets, especially for making Vanadium-Titanium (V-Ti) magnetite pellets, and achieved qualified V-Ti magnetite oxidized pellets in industrial testing. The behaviors of humic substance-based binders in wet balls, dry balls and fired balls were well investigated. Moreover, MHA binder was gradually tested in a lab for pelletization of several other types of iron ore concentrates, such as magnetite from different districts, specularite and fluxed hematite, and good quality pellets were obtained. A review of the development of a humic substance-based binder and its characteristics, preparing method, and behaviors in pelletizing were considered in this paper.     

铁矿球团用有机黏结剂研究进展

 随着钢铁行业绿色低碳转型,使用有机黏结剂替代膨润土已经是铁矿球团工序提质降耗的必然趋势。然而,有机黏结剂彻底替代膨润土的技术壁垒仍未突破,严重限制了其在工业生产中的广泛应用。有机黏结剂的黏结效用也是控制球团强度的关键因素,研究其在球团生产中的作用机理对提高球团强度以及开发具有国内知识产权的新型有机黏结剂意义重大。通过总结有机黏结剂在铁矿球团中的研究进展,旨在为其在中国钢铁行业的广泛应用以及新型有机黏结剂的研发工作提供理论指导与试验依据。在介绍理想有机黏结剂分子结构模型的基础上,揭示了4种常见有机黏结剂的结构及特性。重点讨论了黏度和吸水性对有机黏结剂黏结效用的作用机理,有机黏结剂的高黏度特性能够调节球团颗粒间液桥黏滞力大小,从而显著提高生球强度;吸水性是有机黏结剂调控生球自由水含量的重要特性,只有在最佳吸水率下,才能获得强度较高、粒径均匀的生球。总结了有机黏结剂的常见优缺点,其主要优点是微量高效、烧失量大、基本不影响球团铁品位,缺点是生产球团矿缺乏渣相固结而强度不足。分析了优化原料粒度组成、添加含硼化合物及分散剂等强化有机黏结剂球团生产的调控手段,并展望了有机黏结剂未来的发展方向。     

Pelletization Using Humic Substance-based Binder

Humic substances exist widely in lignite coal as high molecular weight organic molecules. They can be used as binders in iron ore pelletization mostly in the form of salt, such as sodium humate and amine humate via extraction from lignite coal. It is worth determining if lignite can be used as a binder without extraction. As a composite binder of organic and inorganics, due to the combustion of humic substance, the strength of fired pellets made with humic substance-based binder decreases slightly. To compensate for this defect and make stronger pellets, cheap calcium bentonite was added into humic substance binder. In this study, a fluxed hematite concentrate was pelletized with various types of binders: lignite plus sodium hydroxide, calcium bentonite activated with modified humic acid (MHA), and MHA binder. Good quality pellets were obtained at optimal parameters. The results show that without extraction procedure, lignite plus sodium hydroxide can be directly used as a binder in pelletization of fluxed hematite; that calcium bentonite improves pellet strength when added to MHA; and that humic substance can partly replace calcium bentonite, reducing the dose of calcium bentonite.     

Use of Iron Ore Fines in Cold-Bonded Self-Reducing Composite Pellets

The feasibility of producing direct reduced iron from cold-bonded, self-reducing composite pellets, constituted from beneficiated iron ore slime, coke, and different binders (dextrin, bentonite, calcium lignosulfonate, and carboxymethyl-cellulose [CMC]) was studied. This was done using a design of experiments approach. It was found that as-received beneficiated iron ore slime is suitable as a raw material for the production of self-reducing composite pellets with carboxymethylcellulose as the most suitable binder. Dry strengths in excess of 300 N/pellet were attained by curing the pellets under ambient conditions. The composite pellets reduced within 20 min to degrees of metallization in excess of 90% at 1100°C, with decrepitation indices significantly below 5%. The degree of metallization of composite pellets increased with an increase in reduction temperature (from 1000 to 1100°C), reduction time (20 min. vs. 40 min), and coke quantity (15% vs. 20%). CMC was identified as the most economical and suitable binder for the Sishen concentrate.     

Effects of Binder on the Properties of Iron Ore-Coal Composite Pellets

Large amounts of fines and superfines are generated in Indian iron ore and coal mines due to mechanized mining and mineral dressing operations. Utilization of these fines for extracting metal is of vital concern for resource utilization and pollution control. For agglomeration of these fines, a suitable binder is required. Iron ore-coal composite pellets were prepared by cold bonding. Various binders such as lime, Ca(OH)₂, slaked lime, dextrose, molasses, and sodium polyacrylate (SPA), alone or in combination, were employed for making composite briquettes. The slaked lime–dextrose combination produced the highest strength among the various binders employed for producing composite briquettes and was therefore selected for producing composite pellets for the smelting reduction. In cold bonding, the composite pellets attain the requisite properties due to physico-chemical changes of the binder in ambient conditions. It was possible to obtain a dry strength of more than 300 N per pellet in some cases and more than 200 N per pellet in many trials. Drop strength and shatter index values of composite pellets were also measured. In the present paper an attempt has been made to evaluate the mechanical properties of cold-bonded composite pellets so as to throw some light on the capacity of these pellets to withstand stresses during handling and transportation.     

The Effect of Calcined Colemanite Addition on the Mechanical Strength of Magnetite Pellets Produced with Organic Binders

Iron ore pellets must have sufficient mechanical strengths against degradation in all stages of pellet production. Low strength is also a problem for product pellets since they abrade during transportation to the reduction furnaces. The use of a binder is necessary to provide sufficient strength to the pellets and for better operation and handling of pellets. Bentonite is the standard binder in the industry; however, it is considered an impurity due to its acid oxide contents. Organic binders have been tested for many years as alternative binder to bentonite. They have been found to give sufficient wet pellet properties. However, they failed to provide sufficient strength to the preheated and fired pellets due to lack of slag bonding. It has been assumed that one possible effective method to improve the preheated and fired pellet strengths is addition of a slag-bonding constituent. In this study, calcined colemanite was added to the pellet feed to overcome the lower strength problem encountered with organic binder use. The strength of pellets produced with organic binders and calcined colemanite alone and in combination was comparatively studied against the strength of pellets made with standard bentonite binder in magnetite concentrate pelletizing. The results showed that addition of calcined colemanite into the pellet mixture improved the preheated and fired pellet strengths of pellets produced with organic binders.     

Study of Organic and Inorganic Binders on Strength of Iron Oxide Pellets

Bentonite is a predominant binder used in iron ore pelletization. However, the presence of a high content of silica and alumina in bentonite is considered undesirable for ironmaking operations. The objective of this study was to identify the alternatives of bentonite for iron ore pelletization. To achieve this goal, different types of organic and inorganic binders were utilized to produce iron oxide pellets. The quality of these iron oxide pellets was compared with pellets made using bentonite. All pellets were tested for physical strength at different stages of pelletization to determine their ability to survive during shipping and handling. The results show that organic binders such as lactose monohydrate, hemicellulose, and sodium lignosulfonate can provide sufficient strength to indurated pellets.     

新型复合粘结剂提高生球质量的作用机理及构效关系

降低膨润土用量是提高球团品位、实现节能减排的有效途径之一。基于新型高效复合粘结剂,通过生球制备、线性拟合分析、生球力学特征分析等手段研究了复合粘结剂对生球质量的影响规律及与重要指标的构效关系,阐明了复合粘结剂提高生球质量的作用机理。结果表明:配比（质量分数）为1.2%膨润土+0.028%有机粘结剂的复合粘结剂球团,落下强度（0.5 m高度落下次数）达到6.2、平均抗压强度达到14.5 N、爆裂温度达到542 ℃,与2.0%膨润土球团相比,生球质量相近,但膨润土消耗减少40%;基于构效关系分析,有机粘结剂对生球落下强度、爆裂温度作用显著,膨润土对干球强度影响更大;有机粘结剂通过增强颗粒的亲水性、毛细力和黏性力强化了生球落下强度,干燥时在表层形成少量孔隙,有利于球团内水分的排出,提高了生球爆裂温度,干燥后以固态连接桥的形式强化干球强度,但是孔隙的位点和尺寸可能会降低干球强度,因此,对干球强度起决定性作用的是膨润土,有机粘结剂对干球强度的影响呈现多面性。      

新型黏结剂强化冷固结球团的作用机理

 黏结剂在冷固结球团中必不可少,目前广泛使用的冷固结球团有机、无机黏结剂如CMC、膨润土和水泥等均会在高温下失效,导致球团高温强度严重下降,因此,寻找一种高温强度良好的黏结剂是目前需要解决的问题。采用新型黏结剂制备冷固结球团,通过XRD和SEM-EDS等对新型黏结剂球团制备原料及球团性能特征进行分析,同时探讨黏结剂对球团冷态抗压强度及高温强度的影响及其作用机理。试验结果表明,黏结剂以流动状态存在于冷固结球团中,可有效吸附或包裹铁矿粉颗粒,增加黏结剂配比可同时提高球团的冷态抗压强度及高温抗压强度;在高温还原性气氛下焙烧冷固结球团,由于发生还原反应,球团金属化率提高,铁矿粉颗粒间空隙增大,导致球团强度下降,焙烧时间为30～90 min时,球团金属化率及抗压强度变化趋势最明显;焙烧初期,球团抗压强度不会发生快速下降,且焙烧结束后球团强度仍可保持为100 N/个左右。     

冷固结球团用地聚合物黏结剂制备参数优化

 针对目前广泛使用的冷固结球团黏结剂高温下失效的缺点，提出使用地聚合物体系材料作为黏结剂，以保证球团的高温性能。首先使用化学分析、X射线衍射分析、红外光谱等方法对地聚合物黏结剂原料性能进行分析；随后制备偏高岭土-水玻璃地聚合物体系黏结剂并进行冷固结压块，分别研究黏结剂制备过程中参数养护温度、养护时间、n（H2O）/n（Na2O）、n（Na2O）/n（SiO2）和n（SiO2）/n（Al2O3）对球团冷态抗压强度的影响，得出此黏结剂制备最佳参数；最后探讨了地聚合物黏结剂球团高温强度演变规律。结果表明，将最优条件下制备的黏结剂应用于冷固结球团，强度可达402.3 N/个 ，满足生产要求；在惰性气氛下，地聚合物黏结剂压块强度随温度升高而升高，且高温下强度增加幅度变大，这表明地聚合物黏结剂在高温下不会失效，且高温有利于黏结剂抗压强度增加。