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Denitrification and microbial community in MBBR using A. donax as carbon source and biofilm carriers for reverse osmosis concentrate treatment

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Journal of Environmental Sciences 2019年第10期31卷 133-143页

作者： Li Li Guokai Yan Haiyan Wang Zhaosheng Chu Zewen Li Yu Ling Tong Wu State Key Laboratory of Environmental Criteria And Risk As sessment Chinese Research Academy of Environmental SciencesBeijing 100012China Engineering Center for Environmental Pollution Control Chinese Research Academy of Environmental SciencesBeijing 100012China National Engineering Laboratory for Lake Pollution Control and Ecological Restoration Chinese Research Academy of Environmental SciencesBeijing 100012China State Environmental Protection Key Laboratory for Lake Pollution Control Chinese Research Academy of Environmental SciencesBeijing 100012China

In this study,raw Arundo donax(A.donax)pieces were applied as carbon source and biofilm carriers for denitrification in a lab-scale moving bed biofilm reactor(MBBR)for the treatment of reverse osmosis concentrate gathered from local wastewater reuse plant.At stable phase(about 60 days),efficient denitrification performance was obtained with73.2%±19.5%NO3--N average removal and 8.10±3.45 g N/(m3·day)NO3--N average volumetric removal rate.Mass balance analysis showed that 4.84 g A.donax was required to remove 1 g TN.Quantitative real-time PCR analysis results showed that the copy numbers of 16S r-RNA,narG,nirS,nosZ and anammox gene of carrier biofilm and suspended activated sludge in the declination phase(BF2 and AS2)were lower than those of samples in the stable phase(BF1 and AS1),and relatively higher copy numbers of nirS and nirK genes with lower abundance of narG and nosZ genes were observed.High-throughput sequencing analysis was conducted for BF2 and AS2,and similar dominant phyla and classes with different abundance were obtained.The class Gammaproteobacteria affiliated with the phylum Proteobacteria was the most dominant microbial community in both BF2(52.6%)and AS2(41.7%).The PICRUSt prediction results indicated that 33 predictive specific genes were related to denitrification process,and the relative abundance of 18 predictive specific genes in BF2 were higher than those in AS2.

关键词： Arundo donax carbon source Denitrification MBBR Reverse osmosis concentrate Nitrate removal Microbial community High-throughput sequencing

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Preparing high-purity iron by direct reduction?smelting separation of ultra-high-grade iron concentrate

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International Journal of Minerals,Metallurgy and Materials 2020年第4期27卷 454-462页

作者： Feng Li Qing-jie Zhao Man-sheng Chu Jue Tang Zheng-gen Liu Jia-xin Wang Sheng-kang Li School of Metallurgy Northeastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

A new process for preparing high-purity iron(HPI)was proposed,and it was investigated by laboratory experiments and pilot tests.The results show that under conditions of a reduced temperature of 1075°C,reduced time of 5 h,and CaO content of 2.5wt%,a DRI with a metallization rate of 96.5%was obtained through coal-based direct reduction of ultra-high-grade iron concentrate.Then,an HPI with a Fe purity of 99.95%and C,Si,Mn,and P contents as low as 0.0008wt%,0.0006wt%,0.0014wt%,and 0.0015wt%,respectively,was prepared by smelting separation of the DRI using a smelting temperature of 1625°C,smelting time of 45 min,and CaO content of 9.3wt%.The product of the pilot test with a scale of 0.01 Mt/a had a lower impurity content than the Chinese industry standard.An HPI with a Fe purity of 99.98wt%can be produced through the direct reduction?smelting separation of ultra-high-grade iron concentrate at relatively low cost.The proposed process shows a promising prospect for application in the future.

关键词： ultra-high-grade iron concentrate high-purity iron coal-based direct reduction smelting separation pilot test

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Microwave strengthens decomposition of mixed rare earth concentrate: Microwave absorption characteristics

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Journal of Rare Earths 2019年第5期37卷 541-546页

作者： Yukun Huang Ting'an Zhang Zhihe Dou Guozhi Lv Guihong Han Weijun Peng School of Chemical Engineering and Energy Zhengzhou University Laboratory of Special Metallurgy and Process Engineering School of Metallurgy Northeastern University

The potential application of microwave heating technology for processing the mixed rare earth concentrate was systematically investigated by analyzing the microwave absorption characteristics in this study. The complex permittivity was measured through resonant cavity perturbation method. The variations of permittivity, the loss factor, loss tangent and the penetration depth with the increasing temperature were investigated numerically. The results indicate that the permittivity increases as the temperature increases, and temperature has a pivotal effect on it. The mixed concentrate is high loss material at the temperature range from 600 to 800℃ according to theoretical analyses of loss tangent and penetration depth. The results of phase transition analysis prove that the variation of microwave absorption characteristics of mixed concentrate is caused by the changes of crystal and lattice structures.The reflectivity, loss factor and penetration depth of the mixed concentrate were also calculated, and the results indicate that processing the mixed concentrate by microwave heating is of high feasibility and industrial potential.

关键词： Microwave processing Microwave absorption characteristics Dielectric constant Loss tangent Mixed rare earth concentrate

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Decomposition process of bastnaesite concentrate in NaOH-CaO-H2O system

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Journal of Rare Earths 2019年第7期37卷 760-766页

作者： Jiang Liu Ting’an Zhang Zhihe Dou Yan Liu Guozhi Lv Key Laboratory of Ecological Metallurgy of Multi-Metal Intergrown Ores of Ministry of Education School of Metallurgy Northeastern University

A novel process of calcification-leaching for bastnaesite concentrate(REFCO3) was proposed. The prior calcification was carried out in the system of NaOH-CaO-H2O and the lgC-pH pattern for Ce-F-Ca-C-H2O system was drawn. The thermodynamics result indicates that decomposition for bastnaesite requires certain alkaline condition, but excessive alkalinity also causes decomposition of CaF2. XRD and SEM-EDS analyses on the calcification-leaching process reveal that bastnaesite first decomposes into RE(OH)3 and CaF2. Then, by HCl leaching rare earths were extracted,while CaF2 was left in the leaching residue. In addition, effects of temperature, time, NaOH and CaO on the calcification were investigated. The results show that the leaching rate of rare earths(REs)reaches 72.5 wt%, at the same time 99.2 wt% of F is left in leaching residue with 20 wt% NaOH and 38 wt% CaO at 493 K for 180 min.

关键词： Bastnaesite concentrate Calcification process Thermodynamics Fluorine Rare earths

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Effect of reductant type on the embedding direct reduction of beach titanomagnetite concentrate

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International Journal of Minerals,Metallurgy and Materials 2019年第2期26卷 152-159页

作者： Yong-qiang Zhao Ti-chang Sun Hong-yu Zhao Chao Chen Xiao-ping Wang Key Laboratory for High-Efficient Mining and Safety of Metal Mines Ministry of Education University of Science and Technology Beijing School of Civil and Resource Engineering University of Science and Technology Beijing

Iron and titanium were recovered from beach titanomagnetite(TTM) concentrate by embedding direct reduction and magnetic separation. The reduction products and the effects of the reductant type and reduction temperature on the reduction behavior were investigated. The results showed that the reduction of TTM concentrate was strongly related to the gasification reactivity of the reductant. Bitumite presented a better product index than wheat-straw biochar and coke, mainly because the gasification reactivity of bitumite was better than that of the other reductants. In addition, high temperatures were not beneficial to embedding direct reduction because of the emergence of a molten phase and iron-joined crystals, which in turn reduced the diffusion rate of the reducing gas and impeded the reduction reaction in the central area of the roasted briquette. The use of bitumite as the reductant at a C/Fe molar ratio of 1.4 and a reduction temperature of 1200°C for 120 min resulted in direct-reduction iron powder assaying 90.28 wt% TFe and 0.91 wt% TiO_2 with an iron recovery of 91.83% and titanium concentrate assaying 46.01 wt% TiO_2 with a TiO_2 recovery of 91.19%. Titanium existed mainly in the form of anosovite and ilmenite in the titanium concentrate.

关键词： beach titanomagnetite concentrate embedding direct reduction magnetic separation reductant reduction temperature

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Structural, compositional and mineralogical characterization of carbonatitic copper sulfide: Run of mine, concentrate and tailings

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International Journal of Minerals,Metallurgy and Materials 2019年第2期26卷 143-151页

作者： Kolela J Nyembwe Elvis Fosso-Kankeu Frans Waanders Kasongo D Nyembwe Water Pollution Monitoring and Remediation Initiatives Research Group School of Chemical and Minerals Engineering Faculty of Engineering North-West University School of Mining Metallurgy and Chemical Engineering Faculty of Engineering and the Built Environment University of Johannesburg

The aim of this study was to determine the structural, compositional, and mineralogical composition of carbonatitic copper sulfide concentrator plant streams. Three samples, each from a different stream(run of mine(ROM), concentrate, and tailings) of a copper concentrator were characterized using various techniques, including stereomicroscopy, X-ray fluorescence, X-ray diffraction, Fourier transform infrared(FTIR) spectroscopy, scanning electron microscopy(SEM) in conjunction with energy-dispersive X-ray spectroscopy(EDS), and optical microscopy. The results reveal that each stream possesses its own unique compositional features. Carbonate minerals associated with calcite and dolomite, followed by quartz, remain the major minerals in both the ROM and tails streams. In the ROM stream, chalcopyrite appears to occur as veins within the carbonatite-hosting ore body. Mineral phase mutation was discovered in the tails stream because magnetite formerly identified in the ROM as the primary iron oxide had evolved into hematite. This metamorphosis was likely promoted by the concentration process. The concentration process was effective, upgrading the chalcopyrite content from 2 wt% in the ROM stream to 58 wt% in the concentrate stream; it was accompanied by bornite(4 wt%), anilite(3 wt%), and digenite(2.5 wt%). In addition, the concentrate stream exhibited properties distinctive from those of the other streams. The FTIR analysis showed the existence of a sulfide group related to the chalcopyrite mineral. Free chalcopyrite grains were observed in the concentrate by SEM analysis, and their mineral presence was supported by the EDS analysis results. All characterization techniques corresponded well with each other regarding the structure, chemistry, and composition of the samples.

关键词： chalcopyrite mineral characterization phase mutation concentrate streams

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Kinetic study on bastnaesite concentrate mechanochemical decomposition in NaOH solution

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Journal of Rare Earths 2020年第4期38卷 418-426页

作者： Jiang Liu Zhihe Dou Ting’an Zhang Key Laboratory of Ecological Metallurgy of Multi-Metal Intergrown Ores of Ministry of Education School of MetallurgyNortheastern UniversityShenyang 110819China

Mechanochemical reaction involves simultaneous chemical reaction and particle crushing;the latter increases the effective reaction area and improves the reactivity,thus enhancing its kinetics.The classical shrinking core model was used to model the kinetics of bastnaesite mechanochemical decomposition in NaOH solution,which shows a questionable result.Mechanochemical reaction is a dynamic process,where the particle shape and concentration in reaction interface undergo constant change.Thus,a physically consistent model was applied to describe the kinetics.The variations in OH^-concentration and particle shape were considered in the revision of model.Considering the variation in OH^-concentration in solution with time,the model with varying OH^-concentration agrees better with the experimental data,improving the regression coefficients to between 0.936 and 0.992.By introducing fractal geometry to deal with the irregular system,the model was further optimized,and the regression coefficients increase to between 0.940 and 0.997.All these models considere shrinking particle approaches and controlling mechanisms for the diffusion and chemical reaction.Finally,the fractal model with varying OH^-concentration was selected to describe the mechanochemical decomposition of bastnaesite,which indicates that the process is controlled by chemical reaction.

关键词： Bastnaesite concentrate Mechanochemical decomposition Sodium hydroxide Kinetics Rare earths

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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

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Study on Roasting Decomposition of Mixed Rare Earth concentrate in CaO-NaCl-CaCl_2

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Journal of Rare Earths 2006年第Z2期24卷 23-27页

作者：吴文远边雪孙树臣涂赣峰 School of Materials & Metallurgy Northeastern University

The decomposed process of bastnaesite, monazite and mixed rare earth concentrate in CaO-CaCl-CaCl2 was studied by means of TG-DTA method. The relationship among decomposition ratio, roasting temperature, and CaO-NaCl addition was studied by the quadratic regression orthogonal analysis, and then the regression equation was obtained. Through analysis, the optimum process conditions of mixed rare earth concentrate decomposed by CaO-CaCl-CaCl2 were obtained as follows: roasting temperature: 700 ℃, CaO addition: 15%, NaCl-CaCl2 addition: 10%, roasting time: 60 min, the decomposition ratio: 91.3%.

关键词： mixed rare earth concentrate roasting CaO-CaCl-CaCl2

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Study on element detection and its correction in iron ore concentrate based on a prompt gamma-neutron activation analysis system

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Nuclear Science and Techniques 2019年第4期30卷 44-52页

作者： Long Zhao Xu Xu Jing-Bin Lu Ya-Lin Gong Xiang-Lin Li Wei Zhang Qing-Min Shang Qing-Feng Song Yan-Feng Li College of Physics Jilin University Dandong Dongfang Measurement & Control Technology Co. Ltd Hunan First Normal University

A prompt gamma-neutron activation analysis(PGNAA) system was developed to detect the iron content of iron ore concentrate. Because of the self-absorption effect of gamma-rays and neutrons, and the interference of chlorine in the neutron field, the linear relationship between the iron analytical coefficient and total iron content was poor, increasing the error in the quantitative analysis. To solve this problem, gamma-ray self-absorption compensation and a neutron field correction algorithm were proposed, and the experimental results have been corrected using this algorithm. The results show that the linear relationship between the iron analytical coefficient and total iron content was considerably improved after the correction. The linear correlation coefficients reached 0.99 or more.

关键词： Prompt gamma-neutron activation analysis Self-absorption Energy spectrum Compensation Correction Iron ore concentrate

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