铬铁矿粉烧结试验研究

通过烧结杯试验,对进口铬铁矿粉烧结过程中的焦粉配比、混合料水分、料层高度和烧结负压等工艺参数进行研究,发现该铬铁矿粉可用烧结法进行造块,其产品铬铁烧结矿可作为电炉冶炼铬铁合金的炉料.与普通铁矿烧结相比,铬铁矿烧结主要特征为:燃烧带宽(75.00 mm),烧结温度高(1 450～1 500 ℃),冷却所需时间长.铬矿烧结主要依靠20%左右橄榄石液相粘结为主,同时,Cr2O3固相反应有利于烧结矿固结.铬铁矿粉烧结的成功将为我国铁合金行业充分利用廉价铬铁矿粉提供技术支持,有利于降低铬铁合金生产成本.     

铬铁粉矿球团化预处理分析

介绍了以工程实际采用的南非铬铁矿粉矿、土耳其铬铁矿粉矿为原料,采用磨矿、圆盘造球、干燥预热、氧化焙烧的工艺流程预处理铬铁粉矿,重点研究了铬粉矿、还原剂、粘合剂、预热焙烧温度制度等因素对铬铁粉矿造球的影响。结果表明,采用本工艺流程对铬铁粉矿进行处理,在合适的原料配比、适当的还原剂及粘结剂使用情况下可以得到适合大型铬铁密闭矿热炉冶炼所需的球团矿。     

锰矿粉造块技术研究进展

锰是发展新兴工业所必需的原料，随着锰块矿资源的日益紧缺，高效利用锰矿粉及精矿资源对于降低铁合金生产成本、扩大原料来源具有重要意义。为了改善锰矿电炉冶炼效率，对入炉锰矿粉及精矿进行造块是必不可少的步骤之一。综述了锰矿粉3种主要造块方法及其研究进展，基于天然锰矿粉成分复杂且金属相与脉石矿物结合紧密的特点，对烧结法、球团法及压团法的原料要求、工艺特点、固结机制及产品性能进行了归纳和比较，认为人造富锰块矿入电炉冶炼可以大幅提高电炉冶炼效率。结合当前低碳减排的大背景，对今后锰矿粉造块工艺发展趋势进行了展望。     

铬铁矿粉转底炉预还原工艺

介绍了铬铁矿粉预还原的生产工艺。该工艺代替块状铬铁矿来冶炼高碳铬铁,不仅可以充分利用铬铁矿资源,同时还可以降低高碳铬铁的冶炼电耗、提高封闭电炉产能,经济效益显著。     

适用于高炉冶炼不锈钢母液的含铬炉料制备

使用低品位铬铁精矿(或粉矿)是提高不锈钢产品市场竞争力的有效措施,对精粉进行预先造块是提高熔炉冶炼效率、降低焦比不可缺少的步骤。回顾了中南大学使用低品位南非铬铁精矿制备高品质炉料用于高炉冶炼不锈钢母液工艺的相关研究及经验。前期扩大试验表明,任意铬铁精矿比例条件下均可制备出高强度氧化球团(2 500 N/个)和烧结矿。高压辊磨预处理是强化铬铁精矿造块的关键技术。为获得满足高炉冶炼要求的炉料冶金性能,南非铬铁精矿的使用比例应低于60%。球团烧结技术是对细粒铬铁精矿造块有效且较经济的技术手段,所得含铬烧结矿用于高炉冶炼不锈钢母液工艺是可行的。     

内加碳铬矿还原球团试验

一、前言我国用于铬铁生产的铬矿多为进口,每吨粉矿较块矿进口价约低25美元,因此使用粉铬矿可为国家节约大量外汇,但粉铬矿会给冶炼和环保带来一些麻烦。矿热电炉使用铬矿还原球团生产铬铁,可以减少粉尘污染,改善炉况,增加产量,降低成本,特别是可大幅度降低电耗。内加碳铬矿球团在回转窑内经1300—1350℃还原后,铁、铬还原率为60%,抗压强度为50kg/球。这种还原球团完全可以满足电炉治炼铬铁的需要。     

糖蜜废液在粉矿冶金压球中的应用

我厂在冶炼碳素铬铁和硅锰合金时,常因矿石中含有大量的粉矿,使炉料透气性变坏,炉况恶化,导致电耗升高和封闭炉难于回收煤气。从而,在能源利用、经济效益及环境保护等方面都受到影响。所以避免粉矿入炉是我厂的当务之急。铁合金工业上普遍采用的是烧结和球团造块技术,近年又兴起冷压球工艺,我厂综合了各种造块技术的优缺点后,结合本厂的条件,决定采用冷压球工艺。     

国外铬粉矿的利用途径

电炉冶炼碳素铬铁一般使用块状铬矿,粉矿过高会影响炉子透气性,恶化炉况,从而导致产量低、电耗高。炉子愈大情况愈突出,采用封闭式电炉操作时就更严重。我国铬矿资源比较缺乏,目前国际市场上,块矿长期供应不足,价格高昂,而铬粉     

铬铁矿预还原球团研究及电炉熔炼效果

铬铁矿造块是解决碳素铬铁生产中电耗高、生产率低和环境污染三大问题的主要手段。迄今,在工业上已有四种造块方法可以使之获得不同程度的解决,其中,尤以预还原球团效果最佳。日本在六十年代中期首创的这个工艺一直为人们所公认。     

我国不锈钢原料资源和生产进展

近年来我国不锈钢产能增长迅速,对铬铁和金属镍的需求不断增加。分析了我国铬铁矿和镍矿的资源状况以及碳素铬铁和镍的生产工艺;基于我国铬铁矿和镍矿资源严重短缺的情况,提出在利用国外铬铁矿资源的同时开发新工艺,拓宽国内铬铁矿资源,充分利用廉价铬矿粉,并加强综合利用研究;采用新工艺利用不含或含微量贵金属的硫化镍矿,并开发利用红土矿生产镍的新工艺以保证镍资源的供应。     

Smelting characteristics of fluxed chromite sinter and its performance assessment in electric arc furnace to produce high carbon ferrochrome

More than 80% of the high grade chromite ores are fragile and tend to form fines during their handling. In order to utilise these chromite ore fine, in ferrochrome production, agglomeration is necessary. In the present study, the direct sintering of chromite ore fines in the presence of coke breeze has been carried out, which does neither require further grinding of ore fines (???10?mm) nor binder. It uses suitable fluxes and coke breeze as heat source to raise temperature up to 1600°C and produces a semifused mass (20% molten phases) with good strength. The developed sinter showed very good strength properties suitable for cold handling. Since it contains higher amount of fluxes than conventional pellet, the study on its smelting characteristics is necessary to assess its suitability in Fe–Cr production. In the present paper, smelting reduction characteristics and assessment of its performance with respect to the lump ore in a 50?kVA electric arc furnace have been studied in 10?kg scale. Different smelting parameters such as coke and flux requirement, energy consumption, etc. has been optimised through both thermodynamically and experimentally to get maximum extent of reduction, metallic yield and chromium recovery. Coke (21%), quartzite (7.52%) and bauxite (10%) addition with 45?kWh of heat input was found to be optimum to achieve 76% metallic yield and 91%, chromium recovery. In the comparative study in identical condition, the chromite sinter showed much better metallic yield (76%) and higher chromium content (54.6%) in the produced ferrochrome than the lump ore (70 and 51. 9% respectively) of the same grade.     

高碳铬铁电炉炉衬的损坏及维护

叙述了重钢公司几个高碳铬铁电炉使用全印度粉矿在冶炼过程中炉衬的损坏情况及其原因，提出了炉衬维护中应注意的几个方面。     

Electric resistivity of fine chromite ore: measurement and prediction

Abstract

Fine chromite ore is a common raw material used to produce ferrochrome alloy by submerged electric arc furnace process. The electric resistivity of fine chromite ore determines current distribution, which in turn, affects operation efficiency during the process. The effects of particle size and contact area of the particles on the electric resistivity of several types of chromite were investigated at room temperature. The relationship between the electric resistivity of mixed particles and the volume fraction of lump ore to fine ore was also studied. Contact resistivity decreases with increasing box-counting dimension. Finally, a ‘parallel connection circuit model’ for predicting the electric resistivity of the chromite mixture was developed. Results show that electric resistivity increases as particle size increases, and that the electric resistivity of the mixture decreases with increasing volume ratio of fine ore. The electric resistivity calculated by the parallel connection circuit model is consistent with measurements.

Le minerai fin de chromite est un matériau brut commun utilisé dans la production d’alliage de ferrochrome par le procédé du four électrique à arc submergé. La résistivité électrique du minerai fin de chromite détermine la distribution du courant, qui, à son tour, affecte l’efficacité de l’opération lors du procédé. On a examiné, à la température de la pièce, l’effet de la taille de particule et de l’aire de contact des particules sur la résistivité électrique de plusieurs types de chromite. On a également étudié la relation entre la résistivité électrique de particules mélangées et la fraction volumique du minerai en bloc par rapport au minerai fin. La résistivité par contact diminuait avec une augmentation de la dimension de boîtes. Finalement, on a développé un ″modèle de circuit à connexions en parallèle″ pour la prédiction de la résistivité électrique du mélange de chromites. Les résultats montrent que la résistivité électrique augmente avec une augmentation de la taille de particule et que la résistivité électrique du mélange diminue avec une augmentation de la densité relative de minerai fin. La résistivité électrique calculée au moyen du modèle de circuit à connexions en parallèle est en accord avec les mesures.     

Beneficiation and Agglomeration of Chromite—Its Application in Turkey

Abstract

Chromite. being one of the most important minerals in the metallurgical, chemical and refractory industries, is the only mineral from which chromium metal can be economically produced. As a result of the fast depletion of high grade lump ores, in the coming years 80% of the world production of chromite will be finer than 10 mm and to obtain products of specific quality concentration processes will be inevitable. Taking into account the difficulty in obtaining lump ores, the agglomeration of the fine concentrate will be necessary for the ferrochromium plant.     

使用复合炉底延长中低碳铬铁炉衬寿命的探讨

在中低碳铬铁电炉中使用复合炉底,通过对极心圆直径、炉壳直径、二次电压、炉渣碱度及捣打料对炉底影响的分析,以及对抗高温理论、砌筑工艺、烘炉制度的探讨,总结出了有效延长炉衬寿命的方法。     

Influence of process parameters on reduction contours during production of ferrochromium in submerged arc furnace

Abstract

Contours of iso‐reduction lines in the submerged arc furnace producing ferrochromium were constructed using a mathematical model based on the temperature profile inside the furnace and the kinetics of reduction of chromite ores. The location and the contours of the iso‐reduction lines are significantly influenced by the temperature profile in the furnace. From the model, it is found that ～27% of the furnace volume is used for the reduction of the ore. The contours are significantly influenced by the degree of pre‐reduction of the ore charged into the furnace. The iso‐reduction lines can be used for enhancing the efficiency of the process and for better control of the operation exploiting options such as intelligent distribution of charge materials over the charge bed.

On a construit des lignes de contour d’iso‐réduction dans le four à arc submergé produisant du ferrochrome en utilisant un modèle mathématique basé sur le profil de température à l’intérieur du four et sur la cinétique de réduction des minerais de chromite. La localisation et les contours des lignes d’iso‐réduction sont influencés significativement par le profil de température dans le four. À partir du modèle, on a trouvé qu’environ 27% du volume du four était utilisé pour la réduction du minerai. Les contours sont influencés significativement par le degré de pré‐réduction du minerai chargé dans le four. On peut utiliser les lignes d’iso‐réduction pour augmenter le rendement du traitement et pour mieux contrôler les options d’exploitation de l’opération comme la distribution intelligente des matériaux de la charge sur le lit de chargement.     

Fundamental Research of Making Stainless Steel by Smelting Reduction of Chromite

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Direct chromium alloying by smelting reduction of mill scale and low grade chromite ore

Direct alloying is the process in which all of the elements needed for alloying can be reduced from their oxides in a furnace or a ladle. This process is one way of reducing the amounts of energy and materials, reducing the loss of alloying elements, and improving working condition. Mill scale produced in rolling mills is considered a rich iron source (> 67% Fe) with minimum impurities. In this paper, iron high-Cr alloy was produced by a direct alloying with chromium in carbo- thermal reduction using fine of low grade chromites ore and mill scale. The smelting experimental heats were carried out in a 5?kg pilot plant submerged electric arc furnace. The charging materials and reduction parameters were varied and the optimum conditions for obtaining alloy with the highest metallic yield and the highest iron and chromium recovery were determined. When using coke as the reducing agent in stoichiometric amounts, for a mixture of mill scale (55%) and chromite ore (45%), 89.1% of the iron and 72.5% of the chromium were recovered, producing iron high-Cr alloy containing 17.9%Cr, 3.73%C, 0.46%Mn and 1.47%Si. The maximum iron and chromium recoveries obtained were 99.3% and 72.5%, respectively when using excess carbon. The present study clarifies the possibility of using a mixture of chromite ore , mill scale and coke as the precursor for direct chromium alloying. This method offers an alternative process route with cheaper raw materials and fewer process steps (by avoiding the step of ferrochrome production) for producing high chromium iron or steel alloys.     

红土镍矿处理工艺的现状及发展方向

介绍了电炉法、鼓风炉法、烧结-高炉还原等火法和氨浸、加压酸浸、常压酸浸等湿法处理红土镍矿的主要工艺特点及其现状,结合红土镍矿的性质及其分布特点分析了几种常用处理方法的优势与不足,探讨了未来处理红土镍矿的工艺发展方向.