高压辊磨对含硫酸渣超细铁精粉生球性能的影响

摘要：为解决某钢铁企业配加20%(质量分数)硫酸渣超细铁精粉成球性差、生球性能弱的问题,开展了高压辊磨预处理球团原料实验。探究了辊速、辊压、辊磨比例等因素对混合料的成球性和生球性能的影响,研究了在适宜辊磨参数条件下配加有机黏结剂对球团爆裂性能的提升作用。结果表明：在辊速280r/min、辊压1.0MPa、辊磨比例100%条件下,混合料成球性能和生球性能显著提高,其中,静态成球指数由0.28提高至0.81,生球落下和抗压强度分别由2.9次/(0.5m)、13.62N/个提高至4.2次/(0.5m)、18.52N/个;同时当有机黏结剂配比为0.2%时,生球爆裂温度由385℃提高至445℃,生球落下和抗压强度进一步提高到6.4次/(0.5m)、20.22N/个,生球性能满足生产要求。     

Effect of high pressure roller grinding on green pellets properties of ultra fine iron concentrate containing pyrite cinder

The preparation of pellet mixture by high pressure roller grinding was studied to solve the problem of poor pelletization and green pellet performance for adding 20 mass% pyrite cinder into ultrafine iron concentrate powder. The influences of roller speed, roller pressure, and roller grinding ratio on the mixture′s pelletization and green pellets performance were investigated. Meanwhile, the effect of adding organic binder on the burst temperature of green pellets was evaluated under the condition of suitable roller milling parameters. The results show that under the conditions of roller speed of 280r/min, roller pressure of 1.0MPa, and roller grinding ratio of 100%, the mixture′s static ballability index and green pellets performance are significantly improved. Specifically, the ballability index increases from 0.28 to 0.81, and the drop number and compressive strength of green pellets increase from 2.9times/(0.5m) and 13.62N/pellet to 4.2times/(0.5m) and 18.52N/pellet, respectively. At the same time, when the proportion of organic binder is 0.2 mass%, the burst temperature increases from 385℃ to 445℃, and the drop number and compressive strength of the green pellets are further augmented to 6.4times/(0.5m) and 20.22N/pellet. Finally, the performance of green pellets meet the production requirements.     

A Case Study on Large-scale Grate-kiln Production of Fluxed Iron Oxide Pellets: Zhanjiang Pelletizing Plant of BaoSteel

There has been increasing demands for large-scale pelletization equipment recently in order to improve the composition of blast furnace burden, conserve energy and reduce emission. Accordingly, the BaoSteel built the Zhanjiang palletization plant with the capacity of 5 million-tons per year, which holds the record in the world for the largest grate-kiln to produce fluxed pellets. The features included preprocessing raw materials with the combination of ball mills and high-press roller presses, production of fluxed pellets with limestone, pre-mixing of dust wastes, and advanced desulfurization technologies. This plant has marked an important step in the development of grate-kiln pelletization technology.     

高压辊磨机边料循环工艺在球团生产中的应用

采用边料循环工艺并结合三钢带式焙烧机生产实践,对高压辊磨机预处理铁精矿进行研究。结果表明,增加高压辊磨边料循环比例,铁精矿的比表面积得到了明显提高,成球性能显著改善。在造球水分为8%的条件下,边料循环50%的铁精矿比表面积、所制备生球以及焙烧球团矿各指标与同配比未经高压辊磨处理的铁精矿相比均有明显提高,铁精矿比表面积增加到1 650 cm2/g,生球落下强度达10 次/(0.5 m),返球率降至15%,成品球团矿抗压强度达到2 678 N,膨润土配比减少1.1 %,满足企业生产要求的同时,实现节能降耗的目的。     

Effects of high pressure roller grinding on size distribution of vanadium-titanium magnetite concentrate particles and improvement of green pellet strength

The vanadium-titanium magnetite concentrate from Panxi region of China was pretreated by high pressure roller grinding (HPRG) and then used in pelletization.Size distribution change of the vanadium-titanium magnetite concentrate after HPRG and the improvement of its green pellet strength were investigated.The results indicated that,besides the increase of fine particles,the vanadium-titanium magnetite concentrate after HPRG had a smaller size ratio of fine particle to coarse particle of 0.126,meaning a lower porosity,compared with the size ratio of raw material of 0.157.The concentrate particles were more closely packed when there was a smaller size ratio of fine particle to coarse particle.The particle packing in the green pellets was closer after HPRG,which strengthened the green pellets with an average drop number of 5.1 (drop height of 0.5 m) and average compressive strength of 13.1 N per pellet of 11 mm in diameter.     

低铁高硅赤铁精矿对氧化球团性能的影响

为合理利用国内低铁高硅铁精矿、降低球团生产成本,研究了低铁高硅赤铁精矿对生球、预热球和焙烧球团性能的影响。结果表明,典型的低铁高硅赤铁精矿A较磁铁精矿有更好的润磨性能。赤铁精矿A的亲水性较磁铁精矿强,在保持生球水分不变且赤铁精矿配比较高的条件下(>10%),生球水分不足,生球质量随着赤铁矿配比的提高而变差。随着赤铁精矿A的配比由0提高到50%,预热球强度由588降低到196 N/个,焙烧球团抗压强度由3 425降低到1 368 N/个,赤铁精矿A配比不宜高于30%,适当提高焙烧温度有利于球团抗压强度的提高。配加低铁高硅赤铁精矿A的球团还原膨胀性能和还原性能均有一定程度改善。     

改善超细铁精矿成球性能的实验研究

针对超细粒铁精矿成球性能较差的问题,通过向西澳某超细磁铁精矿A中分别配加不同比例国产某磁铁精矿B或巴西某赤铁精矿C进行造球实验,研究其基本特性和静态成球性能。结果表明:混合铁精矿的成球性能明显高于超细磁铁精矿A单矿。超细磁铁精矿A单矿生球落下强度仅为3.2次/(0.5m),生球爆裂温度为470℃,配加质量分数为20%国产磁铁精矿或10%巴西赤铁精矿时生球落下强度均超过4次/(0.5m),爆裂温度高于500℃。优化配矿是提高西澳超细磁铁精矿生球性能的有效途径之一。     

武钢鄂州球团厂圆筒干燥机改造

武钢鄂州球团厂精矿干燥机自2005年12月投产后,陆续出现托轮轴断裂,托轮、滚圈、挡轮以及大齿圈等部件表面开裂问题,虽经多次修补,始终无法解决,严重影响了生产。通过对出现问题的各部件进行强度和负载计算,从设备结构、尺寸、材质和热处理等方面提出了相应的解决措施。按设计方案改造后,该设备已稳定运行3年多,完全满足了生产要求。     

Application of Modified Humic Acid (MHA) Binder in the Pelletizing Of Fluxed Hematite Concentrate

Modified humic acid (MHA) binder consists of high molecular weight organic molecules and inorganic part. It is extracted from lignite coal with sodium hydroxide and used in pelletization of iron ore concentrates. Our previous study shows that MHA binder is also a potential binder instead of bentonite for pelletizing of fluxed hematite. For evaluating the use of MHA binder in pelletization of fluxed hematite, pelletizing tests were conducted to optimize parameters, such as dose, firing temperature and time. The results show that the qualities of green/dried balls with 0.6 wt% MHA binder are equal to or even better than that of 0.66 wt% bentonite pellets, and that both are much higher than the minimum requirements of the pellets’ strengths. The compression strength of fired pellets also suggested that MHA binder is promising to completely replace bentonite in pelletizing of fluxed hematite concentrate. However, the abrasion rate of the fired pellets with MHA binder is slightly higher than that of bentonite pellets.     

Oxidation and Induration Characteristics of Pellets Made from Western Australian Ultrafine Magnetite Concentrates and Its Utilization Strategy

Western Australian magnetite concentrates normally have ultrafine granularity and much higher specific surface areas than Chinese magnetite concentrates owing to the significant pre-grinding and beneficiation for saleable iron grade.Such characteristics will inevitably affect the subsequent pelletization process.However,very few investigations have been done before.Thus,the oxidation and induration characteristics of pellet made from a Western Australian ultrafine magnetite concentrate were revealed by conducting routine preheating-roasting tests in an electric tube furnace and investigating the microstructure of fired pellets under an optical microscope in comparison with that of pellets made from typical Chinese magnetite concentrate.The liquidus regions of CaO-SiO_2-Fe_2O_3 and CaOSiO_2-Al_2O_3 ternary systems in air at various temperatures were calculated by FactSage software to explain the importance of liquid phase in the consolidation of fired pellets.The results show that pellet made from ultrafine magnetite concentrate possesses better oxidability and preheating performance than that made from Chinese magnetite concentrate.However,it has inferior roasting performance,usually requiring conditions of roasting at 1 280℃ for at least 30 min to acquire sufficiently high compressive strength,which are attributed to higher temperature sensitivity caused by its smaller particle size and less formation of liquid phase because of low impurities like CaO and Al_2O_3 in raw materials.Correspondingly,its roasting performance can be significantly improved by blending with Chinese magnetite concentrates or increasing the pellet basicity(wCaO/wSiO_2).By comprehensive evaluation,blending with Chinese iron ore concentrates is an appropriate way to utilize Western Australia ultrafine magnetite concentrates.     

高压辊磨对赤铁矿粉球团矿焙烧性能的影响

采用管式焙烧炉对一种赤铁矿粉球团的预热焙烧性能进行了研究,结果表明该赤铁矿球团预热焙烧性能较差,预热温度要达到1070℃,焙烧温度要达到1250℃时其预热焙烧球团的抗压强度才能达到生产要求.对该矿粉进行高压辊磨预加工后,其预热和焙烧性能得到改善,其预热和焙烧温度可分别降低70℃和50℃.进一步的研究结果表明,高压辊磨预加工赤铁矿粉后,小于5μm 微细颗粒含量增加,使焙烧球团的孔隙率降低,有利于Fe2 O3晶粒形成大片的晶桥连接,使得焙烧球团抗压强度得到提高.     

Pelletization of hematite concentrates

The pelletization of hematite concentrates from the Belgorod deposit is considered. To obtain information on such pelletization, experiments are conducted with batch of different composition. The solidfuel content is specified in accordance with the requirements of subsequent processing: for blast-furnace smelting; or for direct iron production using the ITmk-3 system. The binders and slag-forming additives are concentrated sulfide-alcoholic mash and milk of lime. By selecting the specific surface of the concentrate and the solid fuel, as well as the type and quantity of strengthening additive, optimal conditions may be selected for batch pelletization with a large quantity of solid fuel.     

高压辊磨机粉碎铁精矿试验研究

通过铁精矿高压辊磨机粉碎试验，分析了高压辊磨机工况参数与铁精矿粉碎效果之间的关系。对高压辊磨机的选用和设计具有指导意义。     

Plate Water Absorption as an Assessment Tool for Organic Binders

Plate water absorption has been traditionally used to assess the binding ability of bentonite clay binders for iron ore concentrate pelletization. Until 1997, there was an accepted test by ASTM, but due to inconstant data this method was withdrawn. This value, however, is still used by some pelletization operations to gauge the efficacy of their bentonite. This test procedure has only been investigated on inorganic binders and never organic binders. This paper seeks to confidently prove that PWA can be used to accurately determine the efficacy of starch binders both alone and in conjunction with bentonite. The role of bentonite as a binder for iron ore concentrate is not only to hold agglomerates together during high temperature operations. But during pelletization it can also mitigate many times its own weight in water. This water absorption capacity aids in retarding the growth rate of pellets, as faster growing pellets tend to be weaker. The value of this water absorption, known as plate water absorption (PWA), is used as a metric to determine the strength and quality of the resulting pellets by industrial pelletizing facilities. As new low silica binders seek to replace bentonite, they too must take on the role of moisture mitigation. This study has shown that starches with lower water absorption capacities tend to have lower compressive strengths. As the water absorption capacity increases so too does the compressive strength. When using only starch, higher absorption capacities lead to lower compressive strengths of pellets exposed to elevated temperatures. When bentonite is used in conjunction with starch, higher water absorption mixtures do exhibit an increase in strength when heated.     

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.     

球团竖炉配加赤铁矿试验及对比分析

主要以球团竖炉使用的常规磁铁精矿为参考对象,使用常规磁铁精矿生产球团矿的最佳生球制备和预热焙烧等参数作为配加赤铁矿的试验条件,研究了两种不同铁精矿不同配比的生球性能和球团矿抗压强度,并分析相对于常规磁铁精矿的变化。通过试验结果分析得出两种精矿合理配比,并通过机理分析、不同温度下生球干燥速度对比和球团矿矿相性质进行研究,为后期工业生产奠定了基础数据和理论分析条件。     

包钢624m~2大型带式球团焙烧机设计创新与应用

包钢新建成一条国内最大的624m~2大型带式焙烧机球团生产线,年产氧化球团500万t。在设计过程中,对风流系统进行了优化设计,自主设计开发了多项新型设备,如大型球团干燥窑、往复式布料机、回转支撑造球机和稳流给料斗等,并集成应用了立式强力混合机和高压辊磨机等多项国内外大型装备。设计过程中充分考虑了节能环保因素,生产能耗低,粉尘排放、噪音污染均维持在较低水平,除尘灰二次利用,无固体废弃物外排。自2015年底投产以来,设备运行稳定,生产指标良好,球团的TFe质量分数达到65%以上,抗压强度不低于3 100N,工序能耗为17.05kg/t,达到国际先进水平,实现了良好的经济社会效益。     

含镍、铬复合氧化球团的制备工艺

 利用廉价的低品位铬铁矿精矿以及红土镍矿制备含镍、铬复合球团,用于高炉生产含镍和铬不锈钢母液,对于保障不锈钢产业的可持续发展具有重要意义。系统研究含镍、铬球团制备工艺,探究红土镍矿配比、铬铁矿配比以及添加剂对球团强度的影响。结果表明,当混合料配比为45%红土镍矿+15%铬铁矿+40%铁精矿时,添加7.7%添加剂的混合料经高压辊磨预处理后可制备出合格生球,在预热1 000 ℃+12 min,焙烧(1 220～1 250 ℃)+12 min的条件下可获得抗压强度大于2 500N/个的成品球团,可用于高炉生产铁、镍和铬三元不锈钢母液。     

Development of Gold Extraction Technology from Refractory Gold Concentrates Based on Fine Grinding

The problem of in-site treatment of refractory gold and silver flotation concentrates is urgent in Russia at present, because the cost of concentrate treatment at copper smelters raises the cost of the recovered gold up to 30%. Sorption leaching with ultrafine pre-grinding of concentrates to a particle size of 0.010-0.020 mm has emerged as one of the perspective methods of handling this problem. A peculiarity of the devised technology is that ultrafine grinding is performed in standard ball mills loaded with different particle size material, thus providing a maximum contact surface. Typical low-coned hydrocyclones with 75 mm, 50 mm, and 35 mm diameters assembled in a multi-cyclone battery are used as classifying equipment. The proposed grinding scheme produces a final product of 98-99% minus 0.020 mm.

Pilot plant tests on pyrite and arsenopyrite concentrates from various deposits of Zabaikalie were carried out. The refractory nature of these concentrates is due to the presence of finely disseminated gold. Gold extraction from these concentrates, ground to 98-99% minus 0.074 mm in hydrometallurgical cycle does not exceed 80%. Concentrate grinding to 98-99% minus 0.020 mm enables a rise in the gold extraction in the subsequent carbon sorption cycle by 10-15% and reduces gold losses in sorption tailings by 3-5 g/t.     

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.