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Influencing factors and mechanism of water absorption process of iron ores during sintering

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 122-130页

作者： Guo-liang Zhang Sheng-li Wu Juan Zhu Yong-zhi Wang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

The appropriate content and distribution of sinter moisture play an important role in the granulation of iron ores. In this study, the effects of porosity, size distribution, and particle shape on the water absorption rate （WAR） of four types of iron ores were analyzed by using the immersion method and capillary water absorption method. In addition, the mechanism underlying the water absorption process in iron ores was unraveled. It is found that the WARs of iron ores decrease quickly with the increase in water absorption time at the initial stages of water absorption. With further increase in absorption time, the WARs decrease gradually, until near 0. iron ores with higher porosity, smaller particle size, and plate-like structure have the higher WARs. Compared with pores in the single-particle iron ore, voids among particles in the multi-particle iron oxide play an important role at the initial stages of water absorption. The water absorption mechanism of all single-particle and multi-particle iron ores analyzed in this study includes four steps, wherein the first three steps play a significant role in the sintering pro-cess.

关键词： iron ores sintering water absorption factor analysis

Influence of gangue existing states in iron ores on the formation and flow of liquid phase during sintering

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International Journal of Minerals,Metallurgy and Materials 2014年第10期21卷 962-968页

作者： Guo-liang Zhang Sheng-li Wu Shao-guo Chen Bo Su Zhi-gang Que Chao-gang Hou School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

Gangue existing states largely affect the high-temperature characteristics of iron ores. Using a micro-sintering method and scan- ning electron microscopy, the effects of gangue content, gangue type, and gangue size on the assimilation characteristics and fluidity of liquid phase of five different iron ores were analyzed in this study. Next, the mechanism based on the reaction between gangues and sintering mate- dais was unraveled. The results show that, as the SiO2 levels increase in the iron ores, the lowest assimilation temperature （LAT） decreases, whereas the index of fluidity of liquid phase （IFL） increases. Below 1.5wt%, Al2O3 benefits the assimilation reaction, but higher concentra- tions proved detrimental. Larger quartz particles increase the SiO2 levels at the local reaction interface between the iron ore and CaO, thereby reducing the LAT. Quartz-gibbsite is more conductive to assimilation than kaolin. Quartz-gibbsite and kaolin gangues encourage the forma- tion of liquid-phase low-Al2O3-SFCA with high IFL and high-Al2O3-SFCA with low IFL, respectively.

关键词： iron ores ore sintering assimilation liquid phase fluidity

Effects of particle characteristics on the granulation ability of iron ores during the sintering process

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International Journal of Minerals,Metallurgy and Materials 2015年第9期22卷 907-916页

作者： Sheng-li Wu Juan Zhu Ji-cheng Bei Guo-liang Zhang Xiao-bo Zhai School of Metallurgical and Ecological Engineering University Science and Technology Beijing State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

The granulation behavior of iron ores is essential for subsequent parameter optimization and efficient granulation, especially under changing material conditions. In this study, the effects of surface properties and particle size were analyzed using a laboratory granulation method; an estimation of the granulation of sintering blends was subsequently conducted for the base ores. Circularity and porosity were observed to negatively affect the granulation of iron ores, whereas wettability positively affected the granulation and was the most influential factor, indicating that wetting of iron ores is desirable during granulation. When iron ores with complex size distributions were granulated, the equivalent surface area was the main influencing factor for coarse particles larger than 1 mm and the ratio of adhering fines to intermediates was the main factor for fine particles smaller than 1 mm. By combining the granulation of coarse and fine particles with their proportioning, we proposed a calculation method for estimating the granulation ability of sintering blends. Good verification was demonstrated with the designed schemes. The results suggest that the developed method is effective for predicting the granulation of iron ore mixtures.

关键词： iron ores granulation particle size distribution sintering

Effectiveness of sodium silicate as gangue depressants in iron ore slimes flotation

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International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 515-522页

作者： Danda Srinivas Rao Tadiparthi Venkata VijayaKumar Sripada Subba Rao Swarna Prabhakar Guntamadugu Bhaskar Raju National Metallurgical Laboratory-Madras Centre Council of Scientific and Industrial Research-Madras ComplexChennai 600 113India

The recovery of iron from the screw classifier overflow slimes by direct flotation was studied. The relative effectiveness of sodium silicates with different silica-to-soda mole ratios as depressants for silica and silicate bearing minerals was investigated. Silica-to-soda mole ratio and silicate dosage were found to have significant effect on the separation efficiency. The results show that an increase of Fe content in the concentrate is observed with concomitant reduction in SiO2 and A1203 levels when a particular type of sodium silicate at a proper dosage is used. The concentrate of 58.89wt% Fe, 4.68wt% SiO2, and 5.28wt% A1203 with the weight recovery of 38.74% and the metal recovery of 41.13% can be obtained from the iron ore slimes with 54.44wt% Fe, 6.72wt% SiO2, and 6.80wt% A1203, when NazSiO3 with a silica-to-soda mole ratio of 2.19 is used as a depressant at a feed rate of 0.2 kg/t.

关键词： iron ores sodium silicate depressants flotation

Influence of hydrogen concentration on Fe_2O_3 particle reduction in fluidized beds under constant drag force

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International Journal of Minerals,Metallurgy and Materials 2015年第1期22卷 12-20页

作者： Lei Guo Han Gao Jin-tao Yu Zong-liang Zhang Zhan-cheng Guo State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

The fixed-gas drag force from a model calculation method that stabilizes the agitation capabilities of different gas ratios was used to explore the influence of temperature and hydrogen concentration on fluidizing duration, metallization ratio, utilization rate of reduction gas, and sticking behavior. Different hydrogen concentrations from 5vol%to 100vol%at 1073 and 1273 K were used while the drag force with the flow of N2 and H2 （N2：2 L·min^-1;H2：2 L·min^-1） at 1073 K was chosen as the standard drag force. The metallization ratio, mean reduc-tion rate, and utilization rate of reduction gas were observed to generally increase with increasing hydrogen concentration. Faster reduction rates and higher metallization ratios were obtained when the reduction temperature decreased from 1273 to 1073 K. A numerical relation among particle diameter, particle drag force, and fluidization state was plotted in a diagram by this model.

关键词： fluidized beds ferric oxide iron ores agglomeration hydrogen drag force

Performance evaluation for selectivity of the flocculant on hematite in selective flocculation

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International Journal of Minerals,Metallurgy and Materials 2013年第12期20卷 1123-1129页

作者： Lopamudra Panda Pradip K.Banerjee Surendra Kumar Biswal R.Venugopal N.R.Mandre Research and Development Tata Steel Ltd. Institute of Minerals and Materials Technology (Council of Scientific and Industrial Research) Indian School of Mines University

Increased demand for iron ore necessitates the utilization of low-grade iron ore fines, slimes, and existing tailings. Selective flocculation can be an alternative physico-chemical process for utilizing these low-grade fines, slimes, and tailings. In selective fiocculation, the most critical objective is the selection of proper reagents that will make fioc of desired minerals. In present study, selective flocculation was applied to ultra-fine synthetic mixtures of hematite and kaolinite, and the Fe value was upgraded up to 65.78% with the reduction of Al2O3 and SiO2 values to 2.65% and 3.6670, respectively. Here, degraded wheat starch was used as a *** this process, separation occurs on the basis of the selectivity of the flocculant. The selectivity of the fiocculant can be quantified in terms of separation efficiency. Here, an attempt was also made to develop a correlation between separation efficiency and major operating parameters such as flocculent dose, pH value, and solid concentration to predict the separation performance.

关键词： hematite kaolinite selective fiocculation modeling iron ores tailings

Drying and preheating processes of iron ore pellets in a traveling grate

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 535-540页

作者： Jun-xiao Feng Yu Zhang Hai-wei Zheng Xiao-yan Xie Cai Zhang School of Mechanical Engineering University of Science and Technology B~ijing Beijing 100083 China

A mathematical model of drying and preheating processes in a traveling grate was presented based on the laws of mass, momentum, heat transfer, and drying semiempirical relations. A field test was systematically carried out in a traveling grate. The effects of pellet diameter, moisture, grate velocity, and inlet gas temperature on the pellet bed temperature were studied. The average relative error between actual measurements and simulations is less than 7.97%, indicating the validity of the model.

关键词： iron ores pelletizing drying preheating numerical methods field test

NO_x reduction by coupling combustion with recycling flue gas in iron ore sintering process

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International Journal of Minerals,Metallurgy and Materials 2011年第4期18卷 390-396页

作者： Yan-guang Chen Zhan-cheng Guo Gen-sheng Feng School of Chemistry and Chemical Engineering No.beast Petroleum University Daqing 163318 China2 Key Laboratory of the Ministry of Education of China for Recycling ＆ Ecological Metallurgy University of Science and Technology Beijing Beijing 100083 China2

A new process called＇NOx reduction by coupling combustion with recycling flue gas（RCCRF）＇was proposed to decrease NOx emission during the iron ore sintering *** simulation test of NOx reduction was performed over sintered ore and in the process of coke ***,NOx reduction was also carried out by sintering pot *** sintered ore,the amount of NOx emission is reduced by 15wt%-25wt% at 400-550oC using 2.0vol% H2 or 2.0vol% CO,or reduced by 10wt%-30wt% at 560-720oC using 0.15vol% *** reduction is around 10wt% by coupling combustion of pyrolysis gas and coke,or around 16wt% by recycling flue gas into coke *** RCCRF,the maximum NOx reduction ratio is about 23wt% in coke combustion experiment and over 40wt% in sintering pot test.

关键词： nitrogen oxides combustion flue gases iron ores sintering

Morphological and mineralogical characterizations of oolitic iron ore in the Exi region, China

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International Journal of Minerals,Metallurgy and Materials 2013年第2期20卷 113-118页

作者： Shao-xian Song Ernesto Fabian Campos-Toro Yi-min Zhang Alejandro Lopez-Valdivieso School of Resources and Environmental Engineering Wuhan University of Technology Instituto de Metalurgia Universidad Autonoma de San Luis Potosi

The morphological and mineralogical characterizations of a Chinese oolitic iron ore （Exi deposit） were studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy in this work. It is shown that the Exi ore is mainly composed of hematite, quartz, apatite, and chlorite. The hematite is present as the oolitic layers and in the spaces between the aggregated ooids; quartz exists as granular particles in the spaces and as nucleuses in ooids; the harmful mineral, apatite, is associated with hematite as the oolitic layers, fine dissemination, granular particles in the spaces, and nucleuses in ooids. From the viewpoint of mineral beneficiation, it is hard to separate apatite and chlorite but easy to separate quartz from hematite in the Exi iron ore in recovering the iron values.

关键词： iron ores mineralogy morphology scanning electron microscopy