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Effect of Biochar as Reductant on Magnetizing-roasting Behavior of Pyrite Cinder

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Journal of Iron and Steel Research International 2015年第5期22卷 371-376页

作者： Xiao-hui FAN Qiong DENG min gan Hai-bo WANG School of minerals Processing and Bioengineering Central South University

The effect of biochar substituted for anthracite as reductant on magnetizing-roasting pyrite cinder was in- vestigated. The key of magnetizing-roasting is the gasification reaction between reductants and CO2. Since biochar could react with CO2 more rapidly at lower temperature, the reactivity of biochar is better than that of anthracite. The gasification of biochar could produce reducing condition of φco/（φco--φco2 ） about 10 %- 20 % between 700-- 800 ℃, which is in accord with the atmosphere and temperature of Fe2 O3 reduction. So it is beneficial to the reduc- tion of iron mineral of pyrite cinder. Compared with anthracite, bioehar could decrease the roasting temperature from 825 to 750 ℃ and roasting time from 20 to 15 min, which shows that a better effect of magnetization could be ob- tained in the condition of lower temperature and shorter time. Using biochar as reductant, iron concentrate extracted from pyrite cinder as about 64% iron grade could be produced, and the recovery is over 90% under the condition of above 90% grinding particle less than 0. 045 mm and magnetic intensity of 0. 124--0. 194 T.

关键词： pyrite cinders biochar magnetizing roasting conversion rate

Inhibition of hematite on acid mine drainage caused by chalcopyrite biodissolution

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Chinese Journal of Chemical Engineering 2022年第4期35卷 94-104页

作者： Baojun Yang Wen Luo Maoxin Hong Jun Wang Xueduan Liu min gan Guanzhou Qiu School of minerals Processing and Bioengineering Central South UniversityChangsha 410083China Key Laboratory of Biohydrometallurgy Ministry of EducationCentral South UniversityChangsha 410083China Department of Dermatology The First Hospital of ChangshaChangsha 410005China

Even though biodissolution of chalcopyrite is considered to be one of the key contributors in the formation of acid mine drainage(AMD),there are few studies to control AMD by inhibiting chalcopyrite ***,a novel method of using hematite to inhibit chalcopyrite biodissolution was proposed and *** results indicated that chalcopyrite biodissolution could be significantly inhibited by hematite,which consequently decreased the formation of *** the presence of hematite,the final biodissolution rate of chalcopyrite decreased from 57.9%to 44.4%at 20 *** in turn suggested that the formation of AMD was effectively suppressed under such *** to the biodissolution results,mineral composition and morphology analyses,and electrochemical analysis,it was shown that hematite promoted the formation and accumulation of passivation substances(jarosite and Cu2-xS)on chalcopyrite surface,thus inhibiting the biodissolution of chalcopyrite and limiting the formation of AMD.

关键词： Chalcopyrite Hematite Biodissolution Acid mine drainage Acidithiobacillus ferrooxidans

Vertical Price Transmission in the China's Layer Industry Chain:an Application of FDL Approach

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Agricultural Sciences in China 2011年第11期10卷 1812-1823页

作者： XU Shi-wei DONG Xiao-xia LI Zhe-min LI gan-qiong Key Laboratory of Digital Agricultural Early-Warning Technology Ministry of Agriculture~Agricultural Information Institute ChineseAcademy of Agricultural Sciences Beijing 100081 P.R.China

This paper examines the vertical price relationship between upstream and downstream products in China＇s layer industry chain by estimating elasticity coefficients of the price transmission. We use cointegration tests, error correction models and finite distributed lag models to analyze vertical price shifts between corn, layer feed, egg-laying chicken and egg prices. With monthly data from 1994 to 2010, our results show that various prices in China＇s layer industry chain are well integrated. In addition, our results indicate that both long-run and short-run price relationships between upstream and downstream products in layer industry chain exist and the long-run equilibrium, to a certain extent, may eliminate the short-run dynamics price deviation. We also found that the influence of corn and feed prices on egg prices is still more remarkable than egg-laying chicken prices. Our findings imply that governments should pay more attention to corn and layer feed prices in order to stabilize egg prices under the conditions of market integration.

关键词： finite distributed lag model vertical price transmission layer industry chain China

Variable projection algorithms with sparse constraint for separable nonlinear models

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Control Theory and Technology 2024年第1期22卷 135-146页

作者： Hui-Lang Xu Guang-Yong Chen Si-Qing Cheng min gan Jing Chen College of Computer and Data Science Fuzhou UniversityFuzhou350116FujianChina Fujian Key Laboratory of Network Computing and Intelligent Information Processing Fuzhou UniversityFuzhou350116FujianChina Key Laboratory of Intelligent Metro of Universities in Fujian Fuzhou UniversityFuzhou350116FujianChina Engineering Research Center of Big Data Intelligence Ministry of EducationFuzhou UniversityFuzhou350116FujianChina School of Science Jiangnan UniversityWuxi214122JiangsuChina

Separable nonlinear models are widely used in various fields such as time series analysis, system modeling, and machine learning, due to their flexible structures and ability to capture nonlinear behavior of data. However, identifying the parameters of these models is challenging, especially when sparse models with better interpretability are desired by practitioners. Previous theoretical and practical studies have shown that variable projection (VP) is an efficient method for identifying separable nonlinear models, but these are based on \(L_2\) penalty of model parameters, which cannot be directly extended to deal with sparse constraint. Based on the exploration of the structural characteristics of separable models, this paper proposes gradient-based and trust-region-based variable projection algorithms, which mainly solve two key problems: how to eliminate linear parameters under sparse constraint;and how to deal with the coupling relationship between linear and nonlinear parameters in the model. Finally, numerical experiments on synthetic data and real time series data are conducted to verify the effectiveness of the proposed algorithms.

关键词： Variable projection(VP) Non-smooth constraint Separable nonlinear models

Temperature Field Simulation Model for Rotary Kiln of Iron Ore Oxidized Pellet

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Journal of Iron and Steel Research International 2013年第4期20卷 16-19页

作者： FAN Xiao-hui LI Jun CHEN Xu-ling WANG Yi gan min School of minerals Processing and Bioengineering Central South University

Based on conduction,convection and radiation heat transfer among the flue gas,kiln wall,and the pellet bed material,and on the basis of the coal combustion and analysis of reaction heat of pellet induration in the rotary kiln,the temperature field model of rotary kiln was *** visual studio net,matlab and open source computer vision library as development tools,combining with the ActiveX data objects database technology,the temperature field simulation system for rotary kiln of iron ore oxidized pellet production was *** distribution of pellet and flue gas in rotary kiln was dynamically displayed.

关键词： iron ore oxidized pellet rotary kiln temperature distribution mathematical model

Thermodynamic analysis and reaction behaviors of alkali metal elements during iron ore sintering

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Journal of Iron and Steel Research International 2019年第6期26卷 558-566页

作者： Xiao-hui Fan Yan-nan Wang min gan Zhi-yun Ji Yang Zhou Xu-ling Chen School of minerals Processing & Bioengineering Central South University Changsha 410083 Hunan China

Reaction thermodynamics and behaviors of alkali metal compounds were studied by FactSage7.1 and sinter pot trials. Main transformation behavior of alkali metal compounds was divided into three parts: part of alkali metal chloride was gasified and emitted into the flue gas, and most of alkali metal chloride turned into sulfate, which was remained in the finished sinter, through reacting with sulfur oxide;KAlSi3O8 and NaAlSi3O8 were transformed into KAlSi2O6, NaAlSi2O6 and alkali metal oxides by reacting with calcium oxide. Moreover, newly formed alkali metal oxides turned into sulfate and silicate, entering finished sinter finally. Only a small amount of KAlSi3O8 and NaAlSi3O8 were reduced into gaseous alkali metals in ambient strong reduction atmosphere and removed into the flue gas. 21.67% of potassium and 14.56% of sodiumentered flue gas. In finished sinter, alkali metal elements existed in the form of alkali metal sulfate, silicate and aluminosilicate. The influences on alkali metal elements distribution, basicity (mass ratio of CaO to SiO2 in sinter), sulfur content, chloride content and coal ratio of raw materials indicated that increasing basicity level, rising coal ratio and adding CaCl2 promoted the removal of alkali metal elements into the flue gas. However, with sulfur content increasing in raw materials, alkali metal elements distribution ratio in the finished sinter rose.

关键词： Ironoresintering Potassium Sodium Thermodynamics Distribution Alkali metal

Structure Model of Granules for Sintering Mixtures

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Journal of Iron and Steel Research International 2014年第10期21卷 905-909页

作者： Li-shun YUAN Xiao-hui FAN min gan Gui-ming YANG Yi WANG School of minerals Processing and Bioengineering Central South University

Structure model of granules, boundary value of nucleus and powder, and the relationship between granula- tion efficiency and boundary value were investigated. Granules of sintering mixtures are composed of adhesive powder and nucleus. In the mixtures, particles larger than 1.00 mm act as nucleus and particles smaller than 0.25 mm act as adhesive powder. Particles with size between 0.25--1.00 mm can be adhesive powder as well as nucleus depending on the granulation conditions. When the boundary value is close to 0.25 mm, the granulation efficiency is lower than 50%. When the boundary value is close to 1.00 mm, the granulation efficiency is above 90%. The boundary value is influenced by the iron ore type, granulation moisture, fineness of raw materials and burnt-lime activity. Good adhe- sive capability, suitable moisture content, appropriate particle size distribution and high burnt-lime activity make the boundary value move towards 1.00 mm and improve the granulation efficiency.

关键词： iron ore sintering structure model granulation

Influence of O_2 Content in Circulating Flue Gas on Iron Ore Sintering

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Journal of Iron and Steel Research International 2013年第6期20卷 1-6页

作者： FAN Xiao-hui YU Zhi-yuan gan min LI Wen-qi JI Zhi-yun School of minerals Processing and Bioengineering Central South University

Circulating flue gas can reduce the emission of flue gas , and furthermore , it can reuse the waste heat effectively in the sintering *** with conventional sintering , O2 that gets through the sintering bed decreases because of substituting circulating gas for *** influences of O2 content on sintering process are studied through simulating the flue gas circulation sintering with artificial *** shows that , with the reducing of O2 content in circulating gas , the combustion speed of fuel decreases and incomplete combustion degree increases , which makes the flame front fall behind the heat front and reduces the heat utilization efficiency of *** ultimate result is that the temperature of sintering bed decreases and the liquid phase *** addition , the reducing atmosphere is strengthened because of flue gas circulation , which makes the magnetite increase yet calcium ferrite reduce gradually. Because the content of calcium ferrite with good strength reduces , the sinter yield and tumble strength *** ensure the sinter index , the favorable O2 content of circulating flue gas is no less than 15%.

关键词： flue gas circulation sintering heat front flame front sintering metallogenium

mineralization characteristics of pellets prepared by ultrafine magnetite concentrate:influence on metallurgical property and improving method

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Journal of Iron and Steel Research International 2023年第3期30卷 446-455页

作者： Xiao-hui Fan Zhi-an Zhou Shu Wang min gan Zhi-yun Ji Xu-ling Chen Zhi-yuan Tian School of minerals Processing and Bioengineering Central South UniversityChangsha 410083HunanChina Northern Engineering and Technology Corporation MCCDalian 116600LiaoningChina

The reducing property of pellets prepared by ultrafine magnetite concentrate(UMC)and improving method were *** results show that the reduction degree of UMC pellets is only about 56%compared with that of pellets prepared from ordinary iron ore concentrate with relatively coarse particle size,which is significantly lower than the general reduction degree of about 70%.When the composite binder composed of bentonite and organic binder was added,the reduction degree was significantly increased to 69.66%.The revealed mechanism shows that the reduced pellets with common bentonite have a concentric structure,the oxidation gap between the inner and outer layers is obvious,and the outer dense oxide layer hinders the oxidation and reduction of the inner *** adding the composite binder,the organic components significantly improved the internal porosity of the pellets and the aggregation degree of ultrafine iron ore concentrate particles in the granulation process,forming a porous *** non-uniform double-layer structure is eliminated,and the increased pores are conducive to the internal diffusion of CO,and finally the reduction degree of pellets is increased to the level equivalent to that of ordinary magnetite pellets.

关键词： Ultrafine magnetite concentrate mineralization characteristics Reduction degree Improving method Function mechanism