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Some basic properties of granules from ore blends consisting of ultrafine magnetite and hematite ores

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International Journal of Minerals,Metallurgy and Materials 2019年第8期26卷 953-962页

作者： Cong-cong Yang de-qing zhu Jian Pan Yue Shi School of Minerals Processing and Bioengineering Central South University

Some basic properties of granules,including the granule size distribution,packed-bed permeability,and chemical composition of the adhering layer,were investigated in this study for four iron ore blends consisting of 5wt%,25wt%,and 45wt%ultrafine magnetite and 25wt%ultrafine hematite *** effects of varying the sinter basicity(CaO/SiO2 mass ratio=1.4 to 2.2)and adding ultrafine concentrates on the variation of the adhering-layer composition and granule microstructure were ***,the effect of adhering-layer compositional changes on sintering reactions was discussed in combination with pot sintering results of ore *** sinter basicity led to an increase in the basicities of both the adhering layer and the fine part of the sinter mix,which were higher than the overall sinter *** the sinter chemistry was fixed and fine Si-bearing materials(e.g.,quartz sand)were used,increasing the amount of ultrafine ores in the ore blends tended to reduce the adhering-layer basicity and increase the SiO2 content in both the adhering layer and the fine part of the sinter mix,which will induce the formation of low-strength bonding phases and the deterioration of sinter *** adhering-layer composition in granules can be estimated in advance from the compositions of the-1 mm fractions of the raw materials.

关键词： iron ore granule adhering layer magnetite concentrate sinter basicity

Influence of Mechanical Activation on Acid Leaching dephosphorization of High-phosphorus Iron Ore Concentrates

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Journal of Iron and Steel Research International 2016年第7期23卷 661-668页

作者： de-qing zhu Hao WANG Jian PAN Cong-cong YANG School of Minerals Processing and Bioengineering Central South University

High pressure roll grinding（HPRG）and ball milling were compared to investigate the influence of mechanical activation on the acid leaching dephosphorization of a high-phosphorus iron ore concentrate,which was manufactured through magnetizing roasting-magnetic separation of high-phosphorus oolitic iron *** results indicated that when high-phosphorus iron ore concentrates containing 54.92 mass% iron and 0.76 mass% phosphorus were directly processed through acid leaching,iron ore concentrates containing 55.74mass%iron and 0.33mass%phosphorus with an iron recovery of 84.64%and dephosphorization of 63.79% were *** high-phosphorus iron ore concentrates activated by ball milling were processed by acid leaching,iron ore concentrates containing56.03mass%iron and 0.21mass% phosphorus with an iron recovery of 85.65% and dephosphorization of 77.49%were ***,when high-phosphorus iron ore concentrates activated by HPRG were processed by acid leaching,iron ore concentrates containing 58.02mass%iron and 0.10mass% phosphorus were obtained,with the iron recovery reaching 88.42% and the dephosphorization rate reaching 88.99%.Mechanistic studies demonstrated that ball milling can reduce the particle size,demonstrating aprominent reunion *** contrast,HPRG pretreatment contributes to the formation of more cracks within the particles and selective dissociation of iron and P bearing minerals,which can provide the favorable kinetic conditions to accelerate the solid-liquid reaction *** such,the crystal structure is destroyed and the surface energy of mineral particles is strengthened by mechanical activation,further strengthening the dephosphorization.

关键词： high-phosphorus iron ore concentrate high pressure roll grinding ball milling selective dissociation sulfuric acid leaching dephosphorization iron recovery

Insights on pretreatment of Indian hematite fines in grate-kiln pelletizing process： the choice of grinding processes

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Journal of Iron and Steel Research International 2018年第5期25卷 506-514页

作者： de-qing zhu Zheng-qi Guo Jian Pan Zhao-yuan Wang School of Minerals Processing and Bioengineering CentralSouth University Changsha 410083 Hunan China Engineering design and Research Institute Northern HeavyIndustries Group Shenyang 110141 Liaoning China

Indian hematite fines are normally characterized by high iron grade and minor impurities, which are usually used for sinter fines. With macroscale operations technology of blast furnace in Indian, pellets, as a kind of high-quality materials, attract more and more attention. However, the hematite fines possess the coarse size. Hence, they inevitably need to be further finely ground for pelletizing before balling. The grinding behavior of Indian hematite fines was revealed by conducting the ball milling tests and determining the Bond ball mill work index （Wi）. The results show that Indian hematite fines have an excellent grindability with Wi of only 7.40-7.73 kWh/t, indicating that ball milling is an economically viable way to pretreat Indian hematite fines. Nonetheless, due to poor sedimentation and filtering properties of wet ground products, the dry ball milling is more appropriate to process Indian hematite fines. In addition, the superior quality green balls can be manufactured with dry ground products under the conditions of 0.5% bentonite dosage, 7.5% moisture and balling for 12 min, which further confirmed that the recommended pellet feed preparation technique is reasonable.

关键词： Indian hematite fine · Dry ball milling · Wet ball milling · Bond work index · Sedimentation characteristic ·Filtration characteristic

Grate-kiln pelletization of Indian hematite fines and its industrial practice

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International Journal of Minerals,Metallurgy and Materials 2017年第5期24卷 473-485页

作者： de-qing zhu Feng Zhang Zheng-qi Guo Jian Pan Wei Yu School of Minerals Processing and Bioengineering Central South University Institution of Resources Strategy Wuhan Iron and Steel Corporation

Indian hematite fines normally have a high iron grade and minor impurities; they are usually used as sinter fines for feeding into a blast furnace. In this work, the grindability properties of two kinds of Indian hematite fines and the roasting behaviors and induration characteristics of pellets made from these fines were revealed through experiments involving dry ball milling and small-scale and pilot-scale tests. In addition, the microstructures of the particles of ground India hematite fines and fired pellets were investigated using optical microscopy. On the basis of the results, a grate-kiln production line with an annual output of 1.2 Mt of oxidized pellets was established in India. This pellet plant operates stably and reliably, further confirming that preparing high-quality pellets with Indian hematite fines pretreated by dry ball milling is an industrially feasible process. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

关键词： Ball milling Blast furnaces Industrial management Kilns Milling (machining) Pelletizing

Improving roasting performance and consolidation of pellets made of ultrafine and super high grade magnetite concentrates by modifying basicity

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Journal of Iron and Steel Research International 2020年第7期27卷 770-781页

作者： Feng Zhang de-qing zhu Jian Pan Zheng-qi Guo Meng-jie Xu School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083HunanChina Sinosteel Equipment&Engineering Co. Ltd.Beijing 100000China

For improving the strength of pellets made of ultrafine and super-high-grade magnetite concentrates,the influence of basicity(CaO/SiO2 ratio)on the roasting and consolidation of pellets was *** results showed that with the basicity of pellets increasing from 0.09 to 0.60,the compressive strength of both preheated and roasted pellets achieved an evident improvement from 502 and 2519 to 549 and 3096 N/pellet,respectively;meanwhile,the roasting time decreased from 15 to *** low-viscosity liquid phases were easily generated in fired pellets at the basicity range of 0.40-0.60 under the roasting temperature of 1240℃,filled the voids between hematite particles and tightened the bonding among particles,effectively restraining the generation of concentric cracks and decreasing the porosity of fired pellets;low-viscosity liquid phases facilitated the solid diffusion of hematite,leading to the formation of coarse hematite crystals and thicker connecting necks.

关键词： Basicity Consolidation Ultrafine and super-high-grade magnetite concentrate Fired pellet Compressive strength Liquid phase

Influence of basicity on metallurgical performances of fired super high-grade magnetite pellets in hydrogen-rich gases

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Journal of Iron and Steel Research International 2021年第10期28卷 1212-1222页

作者： Feng Zhang de-qing zhu Jian Pan Zheng-qi Guo Meng-jie Xu College of Materials and Metallurgy Guizhou UniversityGuiyang550025GuizhouChina School of Minerals Processing and Bioengineering Central South UniversityChangsha410083HunanChina Sinosteel Equipment&Engineering Co. Ltd.Beijing100080China

The influence of basicity on the metallurgical performances and reduction characteristics of fired super high-grade magnetite pellets under the simulated shaft furnace gas conditions was *** fired pellets in the basicity range of 0.09(natural basicity)to 1.00 show superior reducibility and low-temperature disintegration ***,in the basicity range of 0.20–0.80,the abnormal swelling of the fired pellets *** basicity from 0.09 to 0.40 promotes the generation of low melting point slag phases and lower porosity of fired pellets,and accelerates the growth and densification of hematite crystals,impeding the reduction of hematite particles and the formation of metallic iron *** addition,the slags that distribute between the hematite particles absorb the reduction stresses by increased distances between the particles during the reduction process,which leads to the large reduction swelling of pellets.

关键词： Ultrafine high-grade magnetite concentrate Basicity Metallurgical performance Reduction behavior Gas-based shaft furnace direct reduction Fired pellet

Upgrading and dephosphorization of Western Australian iron ore using reduction roasting by adding sodium carbonate

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International Journal of Minerals,Metallurgy and Materials 2013年第6期20卷 505-513页

作者： de-qing zhu Tie-jun Chun Jian Pan Li-ming Lu Zhen He School of Minerals Processing and Bioengineering Central South University Commonwealth Scientific and Industrial Research Organisation (CSIRO)

The technology of direct reduction by adding sodium carbonate （Na2CO3） and magnetic separation was developed to treat Western Australian high phosphorus iron ore. The iron ore and reduced product were investigated by optical microscopy and scanning electron microscopy. It is found that phosphorus exists within limonite in the form of solid solution, which cannot be removed through traditional ways. During reduction roasting, Na2CO3 reacts with gangue minerals （SiO2 and A1203）, forming aluminum silicate-containing phosphorus and damaging the ore structure, which promotes the separation between iron and phosphorus during magnetic separation. Meanwhile, Na2CO3 also improves the growth of iron grains, increasing the iron grade and iron recovery. The iron concentrate, assaying 94.12wt% Fe and 0.07wt% P at the iron recovery of 96.83% and the dephosphorization rate of 74.08%, is obtained under the optimum conditions. The final product （metal iron powder） after briquetting can be used as the burden for steelmaking by an alactrie *** furnace to rer）la,ce scrar） steel.

关键词： iron ore reduction sodium carbonate ore roasting magnetic separation phosphorus removal

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

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Journal of Iron and Steel Research International 2016年第9期23卷 924-932页

作者： Cong-cong YANG de-qing zhu Jian PAN Bin-zhi ZHOU Hu XUN department of Ferrous Metallurgy Central South University

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 investi- gations have been done before. Thus, the oxidation and induration characteristics of pellet made from a Western Aus- tralian 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-SiO2-Fe2O3 and CaO-SiO2- Al2O3 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 con- centrate 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 1280℃ for at least 30 rain 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 Al2O3 in raw materials. Correspondingly, its roasting performanee can be significantly improved by blending with Chinese magnetite concen- trates or increasing the pellet basicity （WCaO/WSiO2）. By comprehensive evaluation, blending with Chinese iron ore concentrates is an appropriate way to utilize Western Australia ultrafine magnetite concentrates.

关键词： oxidation induration characteristic ultrafine magnetite concentrate iron ore pellet metallurgical performance

Improving the sintering performance of blends containing Canadian specularite concentrate by modifying the binding medium

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International Journal of Minerals,Metallurgy and Materials 2018年第6期25卷 598-608页

作者： Feng Zhang de-qing zhu Jian Pan Ya-ping Mo Zheng-qi Guo School of Minerals Processing and Bioengineering Central South University Changsha 410083 China Investment Management department of Wuhan Iron and Steel Company Limited Wuhan 430083 China

Canadian specularite concentrate（CSC） possesses high total iron grade and low impurity content. However, due to the poor granulating performance and weak reactivity of CSC at high temperature, the proportion of CSC used in sintering blends is restricted. In this research, the effects of fine limonite, slake lime, and bentonite particles on the granulation performance of blends containing a high ratio of CSC were studied through granulation test. Based on the test results, the effects of modification of the binding medium on the sintering performance of blends containing a high ratio of CSC were revealed by the sintering pot test. Both the granulation property and sintering performance of blends with a high proportion of CSC were improved by modifying the binding medium.

关键词： iron ore binding medium specula^ite concentrate sintering performance