Mechanism for suspension magnetization roasting of iron ore using straw-type biomass reductant

As an alternative reductant for fossil fuel in the future,straw-type biomass contributes to emission reduction and green utilization in the suspension roasting process.In this study,the influences of the roasting time,roasting temperature and dose of straw-type biomass after suspension magnetization roasting(SMR) and separation were investigated.The optimal conditions were determined to be a roasting time of 7.5 min with a straw-type biomass dose of 20 wt% and a roasting temperature of 800℃ in which an iron grade of 71.07% and recovery of 94.17% were obtained for the iron concentrate.The maximum saturation magnetization under optimal conditions was 35.05 A·m^(2)·g^(-1),and the gaseous regulation of the biomass revealed that cumulative reducing gas volume was 293.93 mL at the optimal roasting time of450 s.The transformation of hematite to magnetite was detected by X-ray diffraction(XRD).During microstructure evolution,the outer layer consisting of fissures and tiny holes continuously deepened toward the core.

Reaction behavior and non-isothermal kinetics of suspension magnetization roasting of limonite and siderite

In order to develop limonite and decrease CO_(2) emissions,siderite is proposed as a clean reductant for suspension magnetization roasting(SMR) of limonite.An iron concentrate(iron grade:65.92wt%,iron recovery:98.54wt%) was obtained by magnetic separation under the optimum SMR conditions:siderite dosage 40wt%,roasting temperature 700℃,roasting time 10 min.According to the magnetic analysis,SMR achieved the conversion of weak magnetic minerals to strong magnetic minerals,thus enabling the recovery of iron via magnetic separation.Based on the phase transformation analysis,during the SMR process,limonite was first dehydrated and converted to hematite,and then siderite decomposed to generate magnetite and CO,where CO reduced the freshly formed hematite to magnetite.The microstructure evolution analysis indicated that the magnetite particles were loose and porous with a destroyed structure,making them easier to be ground.The non-isothermal kinetic results show that the main reaction between limonite and siderite conformed to the two-dimension diffusion mechanism,suggesting that the diffusion of CO controlled the reaction.These results encourage the application of siderite as a reductant in SMR.

Triptolide protects astrocytes from hypoxia/reoxygenation injury

Astrocytes in an in vitro murine astrocyte model of oxygen and glucose deprivation/hypoxia and reoxygenation were treated with different concentrations of triptolide （250, 500, 1 000 ng/mL） in a broader attempt to elucidate the protection and mechanism underlying triptolide treatment on astrocytes exposed to hypoxia/reoxygenation injury. The results showed that the matrix metalloproteinase-9, interleukin-1β, tumor necrosis factor α and interleukin-6 expressions were significantly decreased after triptolide treatment in the astrocytes exposed to hypoxia/ reoxygenation injury, while interleukin-10 expression was upregulated. In addition, the vitality of the injured astrocytes was enhanced, the triptolide＇s effect was apparent at 500 ng/mL. These experimental findings indicate that triptolide treatment could protect astrocytes against hypoxia/ reoxygenation injury through the inhibition of inflammatory response and the reduction of matrix metalloproteinase-9 expression.

Review on coal-based reduction and magnetic separation for refractory iron-bearing resources

The application of coal-based reduction in the efficient recovery of iron from refractory iron-bearing resources is comprehensively reviewed.Currently,the development and beneficiation of refractory iron-bearing resources have attracted increasing attention.However,the effect of iron recovery by traditional beneficiation methods is unacceptable.Coal-based reduction followed by magnetic separation is proposed,which adopts coal as the reductant to reduce iron oxides to metallic iron below the melting temperature.The metallic iron particles aggregate and grow,and the particle size continuously increases to be suitable for magnetic separation.The optimization and application of coal-based reduction have been abundantly researched.A detailed literature study on coal-based reduction is performed from the perspectives of thermodynamics,reduction kinetics,growth of metallic iron particles,additives,and application.The coal-based reduction industrial equipment can be developed based on the existing pyrometallurgical equipments,rotary hearth furnace and rotary kiln,which are introduced briefly.However,coal-based reduction currently mainly adopts coal as a reductant and fuel,which may result in high levels of carbon dioxide emissions,energy consumption,and pollution.Technological innovation aiming at decreasing carbon dioxide emissions is a new trend of green and sustainable development of the steel industry.Therefore,the substitution of coal with clean energy(hydrogen,biomass,etc.)for iron oxide reduction shows promise in the future.

Recent process developments in beneficiation and metallurgy of rare earths:A review

Rare earth elements(REEs)are irreplaceable materials supporting low-carbon technology and equip-ment,and their commercial demand and strategic position are becoming increasingly prominent.With the continuous depletion of rare earth(RE)resources,developing high-efficiency beneficiation and eco-friendly metallurgical processes has attracted widespread attention.This paper reviews the major minerals exploited for RE production and their deposits,as well as the beneficiation and metallurgical processes of RE minerals.Bastnaesite,monazite,mixed RE ores,and ion-adsorption clays are the main raw materials in the world to date.RE-bearing ores(except ion-adsorption minerals)are generally beneficiated by flotation,gravity and magnetic separation techniques.The mainstream metallurgical processes for bastnaesite,monazite and mixed RE concentrates are oxidation roasting-HCl leaching,caustic soda decomposition and high-temperature concentrated sulfuric acid roasting,respectively.Ion-adsorption clays are directly processed by in situ leaching-precipitation/solvent extraction.To achieve the sustainable development of RE resources,it is essential to further explore innovative techniques to achievecomprehensive utilization and cleaner production.

Si/Al order and texture orientation optimization of red-emitting Mg_(2)Al_(4)Si_(5)O_(18):Eu^(2+)ceramics for laser phosphor display

Laser phosphor display technology plays an important role in advanced display projection;however,it is a challenge in maintaining excellent color accuracy under high brightness due to the lack of red spectrum.Here,red-emitting Mg_(2)Al_(4)Si_(5)O_(18):Eu^(2+)ceramics as the phosphor wheel have been optimized in chemical compositions and texture orientation.The textured Mg_(2)Al_(4)Si_(5)O_(18):Eu^(2+)ceramics have high transparency and spot limiting ability,accordingly,the ceramic wheel outputs 1,184 lm of ultra-bright red light under 50 W/mm^(2) laser power density.Moreover,the red spectral utilization(over 600 nm)of textured Mg_(2)Al_(4)Si_(5)O_(18):Eu^(2+)ceramics is 2.17 times that of traditional Y_(3)Al_(5)O_(12):Ce^(3+)phosphor wheel.The red-emitting textured Mg_(2)Al_(4)Si_(5)O_(18):Eu^(2+)cordierite ceramic herein enables an improved light-color saturation experience,and it is potential in the next-generation laser phosphor display applications.

Hybrid Eu(II)-bromide scintillators with efficient 5d-4f bandgap transition for X-ray imaging

Luminescent metal halides are attracting growing attention as scintillators for X-ray imaging in safety inspection,medical diagnosis,etc.Here we present brand-new hybrid Eu(II)-bromide scintillators,1D type[Et4N]EuBr3·MeOH and 0D type[Me4N]6Eu5Br16·MeOH,with spin-allowed 5d-4f bandgap transition emission toward simplified carrier transport during scintillation process.The 1D/0D structures with edge/face-sharing[EuBr6]4−octahedra further contribute to lowing bandgaps and enhancing quantum confinement effect,enabling efficient scintillation performance(light yield~73100±800 Ph MeV^(−1),detect limit~18.6 nGy s^(−1),X-ray afterglow~1%@9.6μs).We demonstrate the X-ray imaging with 27.3 lp mm^(−1) resolution by embedding Eu(II)-based scintillators into AAO film.Our results create the new family of low-dimensional rare-earth-based halides for scintillation and related optoelectronic applications.

Integrated multi-mode glass ceramicfiber for high-resolution temperature sensing

Optical temperature sensors,which can accurately detect temperature in biological systems,are crucial to the development of healthcare monitoring.To challenge the state-of-art technology,it is necessary to design single luminescence center doped materials with multi-wavelength emission for optical temperature sensors with more modes and higher resolution.Here,an Er^(3+)single-doped KYF4 nanocrystals glass ceramic with an obvious thermochromic phenomenon is reported for thefirst time,which shows a different temperature-dependent green,red,and near-infrared luminescence behavior based on thermal disturbance model.In addition,Er^(3+)single-doped GCfiber was drawn and fabricated into multi-mode opticalfiber temperature sensor,which has superior measured temperature resolution(<0.5℃),excellent detection limit(0.077℃),and high correlation coefficient(R^(2))of 0.99997.More importantly,this sensor can monitor temperature in different scenarios with great environmental interference resistance and repeatability.These results indicate that our sensor shows great promise as a technology for environmental and healthcare monitoring,and it provides a route for the design of opticalfiber temperature sensors with multi-mode and high resolution.