This article analyzes the current research status and development trend of intelligent technologies for underground metal mines in China, where such technologies are under development for use to develop mineral resour...This article analyzes the current research status and development trend of intelligent technologies for underground metal mines in China, where such technologies are under development for use to develop mineral resources in a safe, efficient, and environmentally friendly manner. We analyze and summarize the research status of underground metal mining technology at home and abroad, including some specific examples of equipment, technology, and applications. We introduce the latest equipment and technolo- gies with independent intellectual property rights for unmanned mining, including intelligent and unmanned control technologies for rock-drilling jumbos, down-the-hole （DTH） drills, underground scrapers, underground mining trucks, and underground charging vehicles. Three basic platforms are used for intelligent and unmanned mining： the positioning and navigation platform, information-acquisition and communication platform, and scheduling and control platform. Unmanned equipment was tested in the Fankou Lead-Zinc Mine in China, and industrial tests on the basic platforms of intelligent and unmanned mining were carried out in the mine. The experiment focused on the intelligent scraper, which can achieve autonomous intelligent driving by relying on a wireless communication system, location and navigation system, and data-acquisition system. These industrial experiments indicate that the technol- ogy is feasible. The results show that unmanned mining can promote mining technology in China to an intelligent level and can enhance the core competitive ability of China＇s mining industry.展开更多
The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectros...The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectroscopic(FTIR), and X-ray photoelectron spectroscopic(XPS). The flotation tests results show that FeCl3·6H2O has a strong activation effect on andalusite and quartz and citric acid has a strong inhibitory effect on activated quartz, thus increasing the floatability difference between quartz and andalusite when the pulp p H is approximately 8. The FTIR, Zeta potential, and XPS analyses combined with the chemical calculation of flotation reagent solutions demonstrate that Fe forms hydroxide precipitates on the surface of andalusite and quartz and that oleate anions and metal ions adsorb onto the surface of the minerals. The elements Al and Fe can be chemically reacted. The anions in citric acid have different degrees of dissolution of Fe on the andalusite and quartz surfaces, thereby selectively eliminating the activation of the elemental Fe on andalusite and quartz and increasing the floatability of andalusite, leading to a better separation effect between andalusite and quartz.展开更多
This study aims to investigate the effect of a cationic-anionic mixed collector(dodecyltrimethyl ammonium bromide/sodium oleate(DTAB/NaOL)on the selective separation of apatite,dolomite,and potassium feldspar.Herein,s...This study aims to investigate the effect of a cationic-anionic mixed collector(dodecyltrimethyl ammonium bromide/sodium oleate(DTAB/NaOL)on the selective separation of apatite,dolomite,and potassium feldspar.Herein,several experimental methods,including flotation experiments,zeta-potential detection,microcalorimetry detection,XPS analysis and FTIR measurements,were used.The flotation tests showed that dolomite and potassium feldspar can be successfully removed from apatite simultaneously when the molar ratio of DTAB to NaOL was 2:1 with pH 4.5.Zeta-potential and microcalorimetry detection suggested that NaOL and DTAB were adsorbed on the surface of dolomite and potassium feldspar respectively,and part of NaOL and DTAB formed co-adsorption on the surface of potassium feldspar to enhance the floatability of potassium feldspar.The XPS and FTIR spectra analysis demonstrated that the cationic collector,DTAB,was first adsorbed on the surface of potassium feldspar through electrostatic attraction in the DTAB/NaOL mixture system.Subsequently,the anionic NaOL collector and cationic DTAB collector form an electron neutralisation complex,thereby resulting in co-adsorption on the surface of potassium feldspar.NaOL was chemically reacted and adsorbed on dolomite surface,but almost no collector was adsorbed on apatite surface.Finally,the adsorption models of different collectors on mineral surface were obtained.展开更多
In the past few decades,microbubble flotation has been widely studied in the separation and beneficiation of fine minerals.Compared with conventional flotation,microbubble flotation has obvious advantages,such as high...In the past few decades,microbubble flotation has been widely studied in the separation and beneficiation of fine minerals.Compared with conventional flotation,microbubble flotation has obvious advantages,such as high grade and recovery and low consumption of flotation reagents.This work systematically reviews the latest advances and research progress in the flotation of fine mineral particles by microbubbles.In general,microbubbles have small bubble size,large specific surface area,high surface energy,and good selectivity and can also easily be attached to the surface of hydrophobic particles or large bubbles,greatly reducing the detaching probability of particles from bubbles.Microbubbles can be prepared by pressurized aeration and dissolved air,electrolysis,ultrasonic cavitation,photocatalysis,solvent exchange,temperature difference method(TDM),and Venturi tube and membrane method.Correspondingly,equipment for fine-particle flotation is categorized as microbubble release flotation machine,centrifugal flotation column,packed flotation column,and magnetic flotation machine.In practice,microbubble flotation has been widely studied in the beneficiation of ultrafine coals,metallic minerals,and nonmetallic minerals and exhibited superiority over conventional flotation machines.Mechanisms underpinning the promotion of fine-particle flotation by nanobubbles include the agglomeration of fine particles,high stability of nanobubbles in aqueous solutions,and enhancement of particle hydrophobicity and flotation dynamics.展开更多
Tragacanth gum(TG)was explored as a depressant to realize the flotation separation of molybdenite and talc.The flotation experiments indicated that when using potassium butyl xanthate(PBX)as a collector,molybdenite sh...Tragacanth gum(TG)was explored as a depressant to realize the flotation separation of molybdenite and talc.The flotation experiments indicated that when using potassium butyl xanthate(PBX)as a collector,molybdenite showed excellent floatability while talc was completely depressed by TG,thus realizing the flotation separation of the two minerals.X-ray photoelectron spectroscopy(XPS)analysis results showed that TG was adsorbed on molybdenite surface via chemisorption.The results of contact angle measurement,Fourier transform infrared(FTIR)spectroscopy,and time-of-flight secondary ion mass spectrometry(ToF-SIMS)indicated that the pre-adsorption of TG on molybdenite could not hinder the further chemisorption of PBX on molybdenite.Because PBX has no collecting ability on talc,the flotation separation of molybdenite and talc came true using PBX to collect molybdenite and TG to depress talc.展开更多
The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China.The mineralization shows common characteristics in their tectonic setting,ore-forming fluid and metallogenic system...The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China.The mineralization shows common characteristics in their tectonic setting,ore-forming fluid and metallogenic system.Sulfidation and fluid immiscibility are two important mechanisms controlling gold precipitation,both of which consume sulfur in the oreforming fluids.The escape of H2S from the main ore-forming fluids and the decrease of total sulfur concentration not only lead to the efficient precipitation of gold,but also result in the crystallization of reducing minerals such as pyrrhotite and oxidizing minerals such as magnetite.Quartz solubility shows strong dependence on temperature,pressure,and CO2 content.The dependence of quartz solubility on pressure is weak at low temperatures,and progressively stronger at higher temperatures.Similarly,the temperature dependence of quartz solubility is relatively low at low pressures,but becomes gradually stronger at high pressures.The results of solubility modeling can constrain the dissolution and reprecipitation behavior of quartz in the oreforming veins and the formation mechanism of different types of quartz veins.The multi-stage mineralization fluid activity resulted in the complex dissolution structure of quartz in the Jiaodong gold veins.Pyrite in the main metallogenic period in the Jiaodong gold deposits shows complex microstructure characteristics at single crystal scale.The trace elements(mainly the coupling of As-and Au-rich belt)and sulfur isotope composition also display a certain regularity.The As-rich fluids might have formed by the initial pulse of ore-forming fluids through As-rich metasedimentary strata,while the As-Au oscillation zone at the margin of pyrite grains is related to the pressure fluctuation caused by fault activity and the local phase separation of fluids.There is a temporal and spatial evolution of gold fineness in the Jiaodong gold deposits.Water/rock reaction(sulfidation)was the main ore-forming mechanism of early gold mineralization,f展开更多
In order to study the influence of various sintering variables more intuitively and clearly,electromagnetic field analysis and computational fl uid dynamics are used to analyze the infl uence of gas flow,heating power...In order to study the influence of various sintering variables more intuitively and clearly,electromagnetic field analysis and computational fl uid dynamics are used to analyze the infl uence of gas flow,heating power and other process parameters on the temperature range of medium-frequency sintering in this paper.The results indicate that the uniformity of temperature fi eld is determined by the gas flow rate and heating power.When the heating power is 50 kW,the stable temperature drops about 10 K for every 1 m^(3)·h^(−1)increase of hydrogen flow.The peak value of the maximum temperature diff erence on the tungsten rods gradually increases with the increase of the hydrogen flow rate,and it appears slightly later.The temperature distribution of tungsten rods in furnace is similar with diff erent hydrogen flow rate.At the same time,the closer to the furnace wall,the higher the temperature of the tungsten rod.The temperature diff erence between tungsten rods mainly occurred within 1 h after the beginning of heating.Increasing the heating power can improve the stable temperature,but has little eff ect on the heating time.Increasing heating power can increase the peak value of the maximum temperature diff erence on the tungsten rods,but has little eff ect on the occurrence time of the peak value of the maximum temperature diff erence on the tungsten rods.Increasing the heating power will increase the temperature diff erence of a single tungsten rod,but the temperature diff erence of a single tungsten rod never exceeds 65 K.This study can be used to guide the process optimization design.Combined with numerical simulation calculation,the sintering parameters with low energy consumption and high temperature uniformity can be quickly and eff ectively found,thus improving the microstructure and properties of sintered tungsten products.展开更多
A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,d...A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,different secondary air positions,and different secondary air ratios on the gas–solid flow characteristics were explored.The results show that the presence of the secondary air makes a core-annular structure of the velocity distribution of particles in the fluidized bed,which enhances the uniformity of particles’distribution and the stability of fluidization.The position and the ratio of the secondary air have a significant impact on the particle distribution,particle flow rate,and gas flow rate in the fluidized bed.When the secondary air position and ratio are optimal,the particles,particle flow rate,and air flow rate in the CFB are evenly distributed,the gas–solid flow state is good,and the CFB can operate stably.展开更多
Estimation of stressses within the tailings slurry during self-weight consolidation is a critical issue for cost-effective barricade design and efficient backfill planning in underground mine stopes.This process requi...Estimation of stressses within the tailings slurry during self-weight consolidation is a critical issue for cost-effective barricade design and efficient backfill planning in underground mine stopes.This process requires a good understanding of self-weight consolidation behaviors of the tailings slurry within practical stopes,where many factors can have significant effects on the consolidation,including drainage condition and cement addition.In this paper,the prepared tailings slurry with different cement contents(0,4.76wt%,and 6.25wt%)was poured into1.2 m-high columns,which allowed three drainage scenarios(undrained,partial lateral drainage near the bottom part,and full lateral drainage boundaries)to investigate the effects of drainage condition and cement addition on the consolidation behavior of the tailings slurry.The consolidation behavior was analyzed in terms of pore water pressure(PWP),settlement,volume of drainage water,and residual water content.The results indicate that increasing the length of the drainage boundary or cement content aids in PWP dissipation.In addition,constructing an efficient drainage boundary was more favorable to PWP dissipation than increasing cement addition.The final stable PWP on the column floor was not sensitive to cement addition.The final settlement of uncemented tailings slurry was independent of drainage conditions,and that of cemented tailings slurry decreased with the increase in cement addition.Notably,more pore water can drain out from the cemented tailings slurry than the uncemented tailings slurry during consolidation.展开更多
Utilizing delayed expansion cemented paste backfill materials(DECPB) in mine backfill operations offers an effective solution to the challenge of achieving proper contact between the in-situ cemented backfill mass and...Utilizing delayed expansion cemented paste backfill materials(DECPB) in mine backfill operations offers an effective solution to the challenge of achieving proper contact between the in-situ cemented backfill mass and the roof in mined-out areas(backfill-roof contact).This article presents recent progress in both theoretical and experimental research concerning DECPB.The types and mechanisms of expansive additives,including expansive agents,foaming agents,and expansive mineral materials relevant to DECPB,are explained,along with their impact on the expansive properties and mechanical characteristics of DECPB.The composition,material characteristics,preparation methods,and controlled release mechanisms of microcapsules are analyzed.Two methods for measuring the volume change rate of paste backfill slurries are discussed.Research indicates that an appropriate content of expansive additives not only enhances the expansive properties of cemented paste backfill materials but also contributes to improving their mechanical properties.Chemical foaming agents and bentonite are found to be more suitable for preparing DECPB compared to expansive agents.The delayed expansion of cemented paste backfill material is influenced by microcapsules,with their wall materials,preparation parameters,and the alkaline slurry environment affecting their controlled release mechanism.Developing and optimizing precise measurement devices and methods forfor the volume change rate of cemented paste backfill materials is essential requirement for studying the performance of DECPB.Combining delayed expansion technology with retarding techniques in cemented paste backfill materials can provide a reliable solution for achieving proper backfill-roof contact in the future.展开更多
Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementi...Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementitious material(CNCM)was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO_(2) mineralization capacity.Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development.Meanwhile,thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO_(2) adsorption amount and carbonation products of CNCM.Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging(BSE)with energy-dispersive X-ray spectrometry.Results showed that among the studied samples,the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO_(2) sequestration amount of 8.51wt%at 80℃and 72 h while presenting the compressive strength of 39.07 MPa.This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO_(2) and exhibit high compressive strength.Although the addition of citric acid did not improve strength development,it was beneficial to increase the CO_(2) diffusion and adsorption amount under the same carbonation conditions from BSE results.This work provides guidance for synthesizing CO_(2)-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals.展开更多
A direct alkaline leaching process was proposed to extract molybdenum and lead from low-grade wulfenite ore containing 2.87%Mo and 9.39%Pb.The results show that increasing temperature and alkali concentration enhances...A direct alkaline leaching process was proposed to extract molybdenum and lead from low-grade wulfenite ore containing 2.87%Mo and 9.39%Pb.The results show that increasing temperature and alkali concentration enhances the extraction of Mo and Pb,and more than 99.7%of Mo and 64.6%of Pb are extracted under conditions of 75℃,L/S of 2:1,leaching time of 1.0 h,initial NaOH concentration of 80 g/L and stirring speed of 100 r/min.The alkaline leaching of molybdenum follows a chemical reaction control mechanism with activation energy of 46.3 kJ/mol.Lead in the residue is recovered by hydrochloric acid leaching.99.8%of lead is leached under the conditions of 80℃,[MnO2]/[Pb]molar ratio of 1.3:1,sodium chloride concentration of 40 g/L,and hydrochloric acid concentration of 3 mol/L,and a product of crystallized PbCl2 with purity higher than 99.5%is obtained after cooling.展开更多
Spectral analysis was a method of identifying substances, determining their chemical composition and calculating their content based on their spectral characteristics. This paper mainly discussed the application of va...Spectral analysis was a method of identifying substances, determining their chemical composition and calculating their content based on their spectral characteristics. This paper mainly discussed the application of various spectroscopic techniques, mainly including atomic absorption spectrometry (AAS) inductively coupled plasma emission spectrometry (ICP-AES) X-ray fluorescence spectroscopy (XRF) atomic fluorescence spectroscopy (AFS) direct reading spectroscopy (OES) glow discharge emission spectroscopy (GD-OSE) laser-induced breakdown spectroscopy (LIBS), in the formulation of non-ferrous metal standards in China. The AAS method was the most widely used single-element microanalysis method among the non-ferrous metal standards. The ICP-AES method was good at significant advantages in the simultaneous detection of multiple elements. The XRF method was increasingly used in the determination of primary and secondary trace elements due to its simple sample preparation and high efficiency. The AFS was mostly detected by single-element trace analysis. OES GD-OES and LIBS were playing an increasingly important role in the new demand area for non-ferrous metals. This paper discussed matrix elimination, sample digestion, sample preparation, instrument categories and other aspects of some standards, and summarized the advantages of spectral analysis and traditional chemical analysis methods. The new methods of future spectroscopic technology had been illustrated in the process of developing non-ferrous metal standards.展开更多
As more and more pollutants threaten human health, it is necessary and essential to develop sensitive, accurate and rapid methods and sensory materials to detect harmful substance. Metal-organic frameworks (MOFs) are ...As more and more pollutants threaten human health, it is necessary and essential to develop sensitive, accurate and rapid methods and sensory materials to detect harmful substance. Metal-organic frameworks (MOFs) are inorganic-organic hybrids assembled from inorganic metal ions or clusters and suitable organic ligands. Zinc-based MOFs (Zn-MOFs) have emerged as one of the most promising sensory material of MOFs for practical applications, and attracted significant attention due to structural diversity and incomparable stability properties. However, there are few reviews on systemic summary of synthesis design, mechanism and application of Zn-MOFs. In this review, we summarize the synthesis design methods, structure types and luminescence mechanism of Zn-MOFs sensor recognition in the past ten years and their applications in metal cations, anions, organic compounds and other analytes. Finally, we present a short conclusion, and look forward to the future development direction of Zn-MOFs.展开更多
Flotation separation of smithsonite from calcite is difficult due to their similar surface properties.In the present study,a reagent scheme of depressant calcium lignosulphonate(CLS) and collector benzyl hydroxamic ac...Flotation separation of smithsonite from calcite is difficult due to their similar surface properties.In the present study,a reagent scheme of depressant calcium lignosulphonate(CLS) and collector benzyl hydroxamic acid(BHA) was introduced in the flotation of smithsonite from calcite.Microflotation tests revealed that the efficient flotation of smithsonite from calcite could only be obtained with the addition order of BHA before CLS,which was opposite to the widely-used order that adding depressant prior to the collector.The zeta potential measurements indicated that BHA selectively adsorbed onto smithsonite surface,then not allowed the CLS adsorption onto the smithsonite surface rather than calcite surface because of the steric hindrance,thereby the smithsonite surface remained hydrophobic while calcite surface became more hydrophilic after the addition of CLS.As a result,the calcite flotation was completely depressed while the smithsonite flotation recovery was still in high value,leading to the optimal flotation separation performance.展开更多
To achieve the utilization of the abandoned ultrafine ilmenite(-20 μm) produced in the titanium magnetite processing plant in Panzhihua,the superconducting high-gradient magnetic separation(SMS) technology was propos...To achieve the utilization of the abandoned ultrafine ilmenite(-20 μm) produced in the titanium magnetite processing plant in Panzhihua,the superconducting high-gradient magnetic separation(SMS) technology was proposed in this study.After optimizing the conditions of magnetic intensity,feeding and pulsation,an SMS concentrate with TiO_(2) grade of 16.03% and TiO_(2) recovery of 66.39% was obtained through one roughing-one cleaning pre-concentration flowsheet.The specific magnetic force and magnetic force were calculated and analysed to illustrate the pre-concentration mechanism,and the results revealed that the combination of high magnetic field and strong pulsating resulted in the effective preconcentration of the ultrafine ilmenite in the SMS process.In addition,the magnetic force analysis indicated that the high magnetic intensity and high magnetic gradient are the key factors of the SMS technology.Furthermore,the EDS-Mapping detection certified that the ultrafine ilmenite was concentrated from the gangue minerals using SMS technology.展开更多
Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by ...Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.展开更多
To remove the key impurity elements,P and B,from primary Si simultaneously,Sr and Zr co-addition to Al-Si alloy systems during solvent refining has been investigated.Sr reacts with Al,Si,and P in the melt to form a P-...To remove the key impurity elements,P and B,from primary Si simultaneously,Sr and Zr co-addition to Al-Si alloy systems during solvent refining has been investigated.Sr reacts with Al,Si,and P in the melt to form a P-containing Al_(2)Si_(2)Sr phase and Zr reacts with B to form a ZrB_(2) phase.In the Al-Si-Sr-Zr system,high removal fractions of P and B in the primary Si,with 84.8%-98.4%and 90.7%-96.7%,respectively,are achieved at the same time,respectively.The best removal effect is obtained in the sample with the addition of Sr-32000+Zr-3000μg·kg^(-1),and the removal fractions of P and B in the purified Si reach 98.4%and 96.1%.Compared with the Sr/Zr single-addition,the removal effects of Sr and Zr co-addition on P and B do not show a significant downward trend,indicating that the nucleation and growth of the B/P-containing impurity phases are mutually independent.Finally,an evolution model is proposed to describe the nucleation and the growth stages of Sr/Zr-containing compound phases,which reveals the interaction between the impurity phases and the primary Si.展开更多
Al coated NdFeB magnets obtained by vacuum evaporation technique were densified by high energy ball milling method.The surface morphology,metal composition and micro structure of the coatings were characterized by sca...Al coated NdFeB magnets obtained by vacuum evaporation technique were densified by high energy ball milling method.The surface morphology,metal composition and micro structure of the coatings were characterized by scanning electron microscopy,X-ray diffraction and X-ray photoelectron spectroscopy,respectively.The anticorrosive properties were investigated by potentiodynamic polarization curves and neutral salt spray test.The pores in the Al coatings of columnar crystals(Al) induced by the evaporation technique,were apparently filled in the following ball milling process,leading to the densification of Al coatings and the evident improvement of the anticorrosive performances.When treated with ball milling for 30 min,the sample achieves the best anticorrosive performances with the self-corrosion potential of-0.87 V,self-corrosion current density of 1.65 μA/cm^(2) and the neutral salt spray(NSS) time of 144 h(red rust).The improvement of the anticorro sive performances of vacuum evaporated Al coating mainly lies in the densification effect of the coating,which depends on different loading conditions of ball milling process.展开更多
Si alloying in the surface layer of NdFeB magnets was realized by thermal diffusion combined with magnetron sputtering.The surface composition,phase structure and morphology of NdFeB(S-Si)specimens were characterized ...Si alloying in the surface layer of NdFeB magnets was realized by thermal diffusion combined with magnetron sputtering.The surface composition,phase structure and morphology of NdFeB(S-Si)specimens were characterized by an X-ray diffractometer,an X-ray photoelectron spectrometer and a field emission scanning electron microscope,respectively.The corrosion resistance of bare NdFeB(S-Si)was analyzed by static full immersion corrosion test and electrochemical experiments.Effects of sputtering and thermal diffusion on the microstructure and corrosion resistance of the surface layer were studied.Results show that surface alloying layer can effectively improve the corrosion resistance of bare NdFeB with the optimized static total immersion corrosion test time in NdFeB(1S-Si)-800 of 36 h,which is much longer than that of the pristine NdFeB(less than 0.5 h).The E_(corr)of NdFeB(1S-Si)-800 positively shifts from-1.05 to-0.92 V,indicating that the corrosion tendency is obviously lower.The J_(corr)is1.45×10^(-6)A/cm^(2)which is 2 orders of magnitude lower than that of the pristine NdFeB(5.25×10^(-4)A/cm^(2)).The intergranular composite oxides existing in Nd-rich phase contribute to the enhancement of corrosion resistance of Si-surface-alloying NdFeB.展开更多
文摘This article analyzes the current research status and development trend of intelligent technologies for underground metal mines in China, where such technologies are under development for use to develop mineral resources in a safe, efficient, and environmentally friendly manner. We analyze and summarize the research status of underground metal mining technology at home and abroad, including some specific examples of equipment, technology, and applications. We introduce the latest equipment and technolo- gies with independent intellectual property rights for unmanned mining, including intelligent and unmanned control technologies for rock-drilling jumbos, down-the-hole （DTH） drills, underground scrapers, underground mining trucks, and underground charging vehicles. Three basic platforms are used for intelligent and unmanned mining： the positioning and navigation platform, information-acquisition and communication platform, and scheduling and control platform. Unmanned equipment was tested in the Fankou Lead-Zinc Mine in China, and industrial tests on the basic platforms of intelligent and unmanned mining were carried out in the mine. The experiment focused on the intelligent scraper, which can achieve autonomous intelligent driving by relying on a wireless communication system, location and navigation system, and data-acquisition system. These industrial experiments indicate that the technol- ogy is feasible. The results show that unmanned mining can promote mining technology in China to an intelligent level and can enhance the core competitive ability of China＇s mining industry.
基金financially supported by the State Key Laboratory of Mineral Processing of BGRIMM Technology Group, China (No.BGRIMM-KJSKL-2017-11)
文摘The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectroscopic(FTIR), and X-ray photoelectron spectroscopic(XPS). The flotation tests results show that FeCl3·6H2O has a strong activation effect on andalusite and quartz and citric acid has a strong inhibitory effect on activated quartz, thus increasing the floatability difference between quartz and andalusite when the pulp p H is approximately 8. The FTIR, Zeta potential, and XPS analyses combined with the chemical calculation of flotation reagent solutions demonstrate that Fe forms hydroxide precipitates on the surface of andalusite and quartz and that oleate anions and metal ions adsorb onto the surface of the minerals. The elements Al and Fe can be chemically reacted. The anions in citric acid have different degrees of dissolution of Fe on the andalusite and quartz surfaces, thereby selectively eliminating the activation of the elemental Fe on andalusite and quartz and increasing the floatability of andalusite, leading to a better separation effect between andalusite and quartz.
基金the Key Projects of National Key R&D Program of China(No.2022YFC2904702).
文摘This study aims to investigate the effect of a cationic-anionic mixed collector(dodecyltrimethyl ammonium bromide/sodium oleate(DTAB/NaOL)on the selective separation of apatite,dolomite,and potassium feldspar.Herein,several experimental methods,including flotation experiments,zeta-potential detection,microcalorimetry detection,XPS analysis and FTIR measurements,were used.The flotation tests showed that dolomite and potassium feldspar can be successfully removed from apatite simultaneously when the molar ratio of DTAB to NaOL was 2:1 with pH 4.5.Zeta-potential and microcalorimetry detection suggested that NaOL and DTAB were adsorbed on the surface of dolomite and potassium feldspar respectively,and part of NaOL and DTAB formed co-adsorption on the surface of potassium feldspar to enhance the floatability of potassium feldspar.The XPS and FTIR spectra analysis demonstrated that the cationic collector,DTAB,was first adsorbed on the surface of potassium feldspar through electrostatic attraction in the DTAB/NaOL mixture system.Subsequently,the anionic NaOL collector and cationic DTAB collector form an electron neutralisation complex,thereby resulting in co-adsorption on the surface of potassium feldspar.NaOL was chemically reacted and adsorbed on dolomite surface,but almost no collector was adsorbed on apatite surface.Finally,the adsorption models of different collectors on mineral surface were obtained.
基金funded by the National Natural Science Foundation of China (No.52004020)Fundamental Research Funds for the Central Universities (No.00007733)+2 种基金Open Foundation of State Key Laboratory of Mineral Processing (No.BGRIMM-KJSKL-2021-13)High-end Foreign Expert Introduction Program (No.G2022105001L)State Key Laboratory of Comprehensive Utilization of LowGrade Refractory Gold Ores,Zijin Mining Group Co.,Ltd.
文摘In the past few decades,microbubble flotation has been widely studied in the separation and beneficiation of fine minerals.Compared with conventional flotation,microbubble flotation has obvious advantages,such as high grade and recovery and low consumption of flotation reagents.This work systematically reviews the latest advances and research progress in the flotation of fine mineral particles by microbubbles.In general,microbubbles have small bubble size,large specific surface area,high surface energy,and good selectivity and can also easily be attached to the surface of hydrophobic particles or large bubbles,greatly reducing the detaching probability of particles from bubbles.Microbubbles can be prepared by pressurized aeration and dissolved air,electrolysis,ultrasonic cavitation,photocatalysis,solvent exchange,temperature difference method(TDM),and Venturi tube and membrane method.Correspondingly,equipment for fine-particle flotation is categorized as microbubble release flotation machine,centrifugal flotation column,packed flotation column,and magnetic flotation machine.In practice,microbubble flotation has been widely studied in the beneficiation of ultrafine coals,metallic minerals,and nonmetallic minerals and exhibited superiority over conventional flotation machines.Mechanisms underpinning the promotion of fine-particle flotation by nanobubbles include the agglomeration of fine particles,high stability of nanobubbles in aqueous solutions,and enhancement of particle hydrophobicity and flotation dynamics.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51664020)the Natural Science Foundation of Jiangxi Province,China(No.20202ACBL214010)+1 种基金Open Foundation of State Key Laboratory of Mineral Processing,China(No.BGRIMM-KJSKL-2020-12)Open Foundation of Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources,China(No.2018TP1002).
文摘Tragacanth gum(TG)was explored as a depressant to realize the flotation separation of molybdenite and talc.The flotation experiments indicated that when using potassium butyl xanthate(PBX)as a collector,molybdenite showed excellent floatability while talc was completely depressed by TG,thus realizing the flotation separation of the two minerals.X-ray photoelectron spectroscopy(XPS)analysis results showed that TG was adsorbed on molybdenite surface via chemisorption.The results of contact angle measurement,Fourier transform infrared(FTIR)spectroscopy,and time-of-flight secondary ion mass spectrometry(ToF-SIMS)indicated that the pre-adsorption of TG on molybdenite could not hinder the further chemisorption of PBX on molybdenite.Because PBX has no collecting ability on talc,the flotation separation of molybdenite and talc came true using PBX to collect molybdenite and TG to depress talc.
基金supported by the National Key Research and Development Program(Grant No.2016YFC0600105)the National Natural Science Foundation of China(Grant Nos.41672094,41772080)。
文摘The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China.The mineralization shows common characteristics in their tectonic setting,ore-forming fluid and metallogenic system.Sulfidation and fluid immiscibility are two important mechanisms controlling gold precipitation,both of which consume sulfur in the oreforming fluids.The escape of H2S from the main ore-forming fluids and the decrease of total sulfur concentration not only lead to the efficient precipitation of gold,but also result in the crystallization of reducing minerals such as pyrrhotite and oxidizing minerals such as magnetite.Quartz solubility shows strong dependence on temperature,pressure,and CO2 content.The dependence of quartz solubility on pressure is weak at low temperatures,and progressively stronger at higher temperatures.Similarly,the temperature dependence of quartz solubility is relatively low at low pressures,but becomes gradually stronger at high pressures.The results of solubility modeling can constrain the dissolution and reprecipitation behavior of quartz in the oreforming veins and the formation mechanism of different types of quartz veins.The multi-stage mineralization fluid activity resulted in the complex dissolution structure of quartz in the Jiaodong gold veins.Pyrite in the main metallogenic period in the Jiaodong gold deposits shows complex microstructure characteristics at single crystal scale.The trace elements(mainly the coupling of As-and Au-rich belt)and sulfur isotope composition also display a certain regularity.The As-rich fluids might have formed by the initial pulse of ore-forming fluids through As-rich metasedimentary strata,while the As-Au oscillation zone at the margin of pyrite grains is related to the pressure fluctuation caused by fault activity and the local phase separation of fluids.There is a temporal and spatial evolution of gold fineness in the Jiaodong gold deposits.Water/rock reaction(sulfidation)was the main ore-forming mechanism of early gold mineralization,f
文摘In order to study the influence of various sintering variables more intuitively and clearly,electromagnetic field analysis and computational fl uid dynamics are used to analyze the infl uence of gas flow,heating power and other process parameters on the temperature range of medium-frequency sintering in this paper.The results indicate that the uniformity of temperature fi eld is determined by the gas flow rate and heating power.When the heating power is 50 kW,the stable temperature drops about 10 K for every 1 m^(3)·h^(−1)increase of hydrogen flow.The peak value of the maximum temperature diff erence on the tungsten rods gradually increases with the increase of the hydrogen flow rate,and it appears slightly later.The temperature distribution of tungsten rods in furnace is similar with diff erent hydrogen flow rate.At the same time,the closer to the furnace wall,the higher the temperature of the tungsten rod.The temperature diff erence between tungsten rods mainly occurred within 1 h after the beginning of heating.Increasing the heating power can improve the stable temperature,but has little eff ect on the heating time.Increasing heating power can increase the peak value of the maximum temperature diff erence on the tungsten rods,but has little eff ect on the occurrence time of the peak value of the maximum temperature diff erence on the tungsten rods.Increasing the heating power will increase the temperature diff erence of a single tungsten rod,but the temperature diff erence of a single tungsten rod never exceeds 65 K.This study can be used to guide the process optimization design.Combined with numerical simulation calculation,the sintering parameters with low energy consumption and high temperature uniformity can be quickly and eff ectively found,thus improving the microstructure and properties of sintered tungsten products.
基金the National Key Research and Development Program of China(grant No.2022YFC2904401)Guangxi Science and Technology Major Project(grant No.GuiKe AA23023033).
文摘A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,different secondary air positions,and different secondary air ratios on the gas–solid flow characteristics were explored.The results show that the presence of the secondary air makes a core-annular structure of the velocity distribution of particles in the fluidized bed,which enhances the uniformity of particles’distribution and the stability of fluidization.The position and the ratio of the secondary air have a significant impact on the particle distribution,particle flow rate,and gas flow rate in the fluidized bed.When the secondary air position and ratio are optimal,the particles,particle flow rate,and air flow rate in the CFB are evenly distributed,the gas–solid flow state is good,and the CFB can operate stably.
基金financially supported by the Young Scientist Project of the National Key Research and Development Program of China (No.2021YFC2900600)the Beijing Nova Program (No.20220484057)financial support from China Scholarship Council under Grant CSC No.202110300001。
文摘Estimation of stressses within the tailings slurry during self-weight consolidation is a critical issue for cost-effective barricade design and efficient backfill planning in underground mine stopes.This process requires a good understanding of self-weight consolidation behaviors of the tailings slurry within practical stopes,where many factors can have significant effects on the consolidation,including drainage condition and cement addition.In this paper,the prepared tailings slurry with different cement contents(0,4.76wt%,and 6.25wt%)was poured into1.2 m-high columns,which allowed three drainage scenarios(undrained,partial lateral drainage near the bottom part,and full lateral drainage boundaries)to investigate the effects of drainage condition and cement addition on the consolidation behavior of the tailings slurry.The consolidation behavior was analyzed in terms of pore water pressure(PWP),settlement,volume of drainage water,and residual water content.The results indicate that increasing the length of the drainage boundary or cement content aids in PWP dissipation.In addition,constructing an efficient drainage boundary was more favorable to PWP dissipation than increasing cement addition.The final stable PWP on the column floor was not sensitive to cement addition.The final settlement of uncemented tailings slurry was independent of drainage conditions,and that of cemented tailings slurry decreased with the increase in cement addition.Notably,more pore water can drain out from the cemented tailings slurry than the uncemented tailings slurry during consolidation.
基金financially supported by the National Natural Science Foundation of China (No.52274122)the Research Fund of BGRIMM Technology Group (No.02-2136)the Youth Innovation Fund of BGRIMM Technology Group (Nos.04-2306,04-2342 and 04-2208)。
文摘Utilizing delayed expansion cemented paste backfill materials(DECPB) in mine backfill operations offers an effective solution to the challenge of achieving proper contact between the in-situ cemented backfill mass and the roof in mined-out areas(backfill-roof contact).This article presents recent progress in both theoretical and experimental research concerning DECPB.The types and mechanisms of expansive additives,including expansive agents,foaming agents,and expansive mineral materials relevant to DECPB,are explained,along with their impact on the expansive properties and mechanical characteristics of DECPB.The composition,material characteristics,preparation methods,and controlled release mechanisms of microcapsules are analyzed.Two methods for measuring the volume change rate of paste backfill slurries are discussed.Research indicates that an appropriate content of expansive additives not only enhances the expansive properties of cemented paste backfill materials but also contributes to improving their mechanical properties.Chemical foaming agents and bentonite are found to be more suitable for preparing DECPB compared to expansive agents.The delayed expansion of cemented paste backfill material is influenced by microcapsules,with their wall materials,preparation parameters,and the alkaline slurry environment affecting their controlled release mechanism.Developing and optimizing precise measurement devices and methods forfor the volume change rate of cemented paste backfill materials is essential requirement for studying the performance of DECPB.Combining delayed expansion technology with retarding techniques in cemented paste backfill materials can provide a reliable solution for achieving proper backfill-roof contact in the future.
基金supported by the Intergovernmental International Science and Technology Innovation Cooperation Key Project of the National Key Research and Development Program of China (No.2022YFE0135100)the National Natural Science Foundation of China (No.52072171)+1 种基金the Beijing Nova Program (No.20220484057)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
文摘Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementitious material(CNCM)was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO_(2) mineralization capacity.Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development.Meanwhile,thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO_(2) adsorption amount and carbonation products of CNCM.Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging(BSE)with energy-dispersive X-ray spectrometry.Results showed that among the studied samples,the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO_(2) sequestration amount of 8.51wt%at 80℃and 72 h while presenting the compressive strength of 39.07 MPa.This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO_(2) and exhibit high compressive strength.Although the addition of citric acid did not improve strength development,it was beneficial to increase the CO_(2) diffusion and adsorption amount under the same carbonation conditions from BSE results.This work provides guidance for synthesizing CO_(2)-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals.
基金Project(2012BAB10B06) supported by the National Science and Technology Pillar Program of ChinaProject(51434001) supported by the National Natural Science Foundation of China
文摘A direct alkaline leaching process was proposed to extract molybdenum and lead from low-grade wulfenite ore containing 2.87%Mo and 9.39%Pb.The results show that increasing temperature and alkali concentration enhances the extraction of Mo and Pb,and more than 99.7%of Mo and 64.6%of Pb are extracted under conditions of 75℃,L/S of 2:1,leaching time of 1.0 h,initial NaOH concentration of 80 g/L and stirring speed of 100 r/min.The alkaline leaching of molybdenum follows a chemical reaction control mechanism with activation energy of 46.3 kJ/mol.Lead in the residue is recovered by hydrochloric acid leaching.99.8%of lead is leached under the conditions of 80℃,[MnO2]/[Pb]molar ratio of 1.3:1,sodium chloride concentration of 40 g/L,and hydrochloric acid concentration of 3 mol/L,and a product of crystallized PbCl2 with purity higher than 99.5%is obtained after cooling.
文摘Spectral analysis was a method of identifying substances, determining their chemical composition and calculating their content based on their spectral characteristics. This paper mainly discussed the application of various spectroscopic techniques, mainly including atomic absorption spectrometry (AAS) inductively coupled plasma emission spectrometry (ICP-AES) X-ray fluorescence spectroscopy (XRF) atomic fluorescence spectroscopy (AFS) direct reading spectroscopy (OES) glow discharge emission spectroscopy (GD-OSE) laser-induced breakdown spectroscopy (LIBS), in the formulation of non-ferrous metal standards in China. The AAS method was the most widely used single-element microanalysis method among the non-ferrous metal standards. The ICP-AES method was good at significant advantages in the simultaneous detection of multiple elements. The XRF method was increasingly used in the determination of primary and secondary trace elements due to its simple sample preparation and high efficiency. The AFS was mostly detected by single-element trace analysis. OES GD-OES and LIBS were playing an increasingly important role in the new demand area for non-ferrous metals. This paper discussed matrix elimination, sample digestion, sample preparation, instrument categories and other aspects of some standards, and summarized the advantages of spectral analysis and traditional chemical analysis methods. The new methods of future spectroscopic technology had been illustrated in the process of developing non-ferrous metal standards.
文摘As more and more pollutants threaten human health, it is necessary and essential to develop sensitive, accurate and rapid methods and sensory materials to detect harmful substance. Metal-organic frameworks (MOFs) are inorganic-organic hybrids assembled from inorganic metal ions or clusters and suitable organic ligands. Zinc-based MOFs (Zn-MOFs) have emerged as one of the most promising sensory material of MOFs for practical applications, and attracted significant attention due to structural diversity and incomparable stability properties. However, there are few reviews on systemic summary of synthesis design, mechanism and application of Zn-MOFs. In this review, we summarize the synthesis design methods, structure types and luminescence mechanism of Zn-MOFs sensor recognition in the past ten years and their applications in metal cations, anions, organic compounds and other analytes. Finally, we present a short conclusion, and look forward to the future development direction of Zn-MOFs.
基金the support of Natural Science Foundation of China (51804238, 51904214)the Open Foundation of State Key Laboratory of Mineral Processing, BGRIMM Technology (No. BGRIMM-KJSKL-2021-22)the Fundamental Research Funds for the Central Universities (2021IVA110, 2021IVA039)。
文摘Flotation separation of smithsonite from calcite is difficult due to their similar surface properties.In the present study,a reagent scheme of depressant calcium lignosulphonate(CLS) and collector benzyl hydroxamic acid(BHA) was introduced in the flotation of smithsonite from calcite.Microflotation tests revealed that the efficient flotation of smithsonite from calcite could only be obtained with the addition order of BHA before CLS,which was opposite to the widely-used order that adding depressant prior to the collector.The zeta potential measurements indicated that BHA selectively adsorbed onto smithsonite surface,then not allowed the CLS adsorption onto the smithsonite surface rather than calcite surface because of the steric hindrance,thereby the smithsonite surface remained hydrophobic while calcite surface became more hydrophilic after the addition of CLS.As a result,the calcite flotation was completely depressed while the smithsonite flotation recovery was still in high value,leading to the optimal flotation separation performance.
基金financial support from the Joint Fund (Key program U2067201) for Nuclear Technology Innovation Sponsored by the National Natural Science Foundation of China and the China National Nuclear CorporationNational key research and development program (2019YFC1907702) Sponsored by MOSTthe Fundamental Research Funds for the Central Universities (N2001013) for supporting this research。
文摘To achieve the utilization of the abandoned ultrafine ilmenite(-20 μm) produced in the titanium magnetite processing plant in Panzhihua,the superconducting high-gradient magnetic separation(SMS) technology was proposed in this study.After optimizing the conditions of magnetic intensity,feeding and pulsation,an SMS concentrate with TiO_(2) grade of 16.03% and TiO_(2) recovery of 66.39% was obtained through one roughing-one cleaning pre-concentration flowsheet.The specific magnetic force and magnetic force were calculated and analysed to illustrate the pre-concentration mechanism,and the results revealed that the combination of high magnetic field and strong pulsating resulted in the effective preconcentration of the ultrafine ilmenite in the SMS process.In addition,the magnetic force analysis indicated that the high magnetic intensity and high magnetic gradient are the key factors of the SMS technology.Furthermore,the EDS-Mapping detection certified that the ultrafine ilmenite was concentrated from the gangue minerals using SMS technology.
基金the financial support from the National Natural Science Foundation of China(No.51774041)。
文摘Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.
基金supported by the National Natural Science Foundation of China(Nos.51804294,51874272,52111540265)Anhui Provincial Natural Science Foundation(No.1808085ME121)+4 种基金the Key Laboratory of Photovoltaic and Energy Conservation Materials,Chinese Academy of Science(No.PECL2021QN003)Hefei Institutes of Physical Science,Chinese Academy of Sciences Director’s Fund(No.YZJJZX202018)International Clean Energy Talent Program by China Scholarship CouncilOpen Foundation of State Key Laboratory of Mineral Processing(No.BGRIMM-KJSKL-2022-23)Open Foundation of State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization(No.CNMRCUKF2205)。
文摘To remove the key impurity elements,P and B,from primary Si simultaneously,Sr and Zr co-addition to Al-Si alloy systems during solvent refining has been investigated.Sr reacts with Al,Si,and P in the melt to form a P-containing Al_(2)Si_(2)Sr phase and Zr reacts with B to form a ZrB_(2) phase.In the Al-Si-Sr-Zr system,high removal fractions of P and B in the primary Si,with 84.8%-98.4%and 90.7%-96.7%,respectively,are achieved at the same time,respectively.The best removal effect is obtained in the sample with the addition of Sr-32000+Zr-3000μg·kg^(-1),and the removal fractions of P and B in the purified Si reach 98.4%and 96.1%.Compared with the Sr/Zr single-addition,the removal effects of Sr and Zr co-addition on P and B do not show a significant downward trend,indicating that the nucleation and growth of the B/P-containing impurity phases are mutually independent.Finally,an evolution model is proposed to describe the nucleation and the growth stages of Sr/Zr-containing compound phases,which reveals the interaction between the impurity phases and the primary Si.
基金supported by the Base of the Key Technologies R & D Program of Anhui Province (1704c0402195)the Fundamental Research Funds for the Central Universities (PA2019GDPK0043,JZ2019HGBZ0142,JZ2019YYPY0291)。
文摘Al coated NdFeB magnets obtained by vacuum evaporation technique were densified by high energy ball milling method.The surface morphology,metal composition and micro structure of the coatings were characterized by scanning electron microscopy,X-ray diffraction and X-ray photoelectron spectroscopy,respectively.The anticorrosive properties were investigated by potentiodynamic polarization curves and neutral salt spray test.The pores in the Al coatings of columnar crystals(Al) induced by the evaporation technique,were apparently filled in the following ball milling process,leading to the densification of Al coatings and the evident improvement of the anticorrosive performances.When treated with ball milling for 30 min,the sample achieves the best anticorrosive performances with the self-corrosion potential of-0.87 V,self-corrosion current density of 1.65 μA/cm^(2) and the neutral salt spray(NSS) time of 144 h(red rust).The improvement of the anticorro sive performances of vacuum evaporated Al coating mainly lies in the densification effect of the coating,which depends on different loading conditions of ball milling process.
基金supported by Hefei Municipal Natural Science Foundation(2021026)the Key Research and Development Project of Anhui Province(202004a05020048,202004a05020051)the Fundamental Research Funds for the Central Universities(PA2020GDJQ0026)。
文摘Si alloying in the surface layer of NdFeB magnets was realized by thermal diffusion combined with magnetron sputtering.The surface composition,phase structure and morphology of NdFeB(S-Si)specimens were characterized by an X-ray diffractometer,an X-ray photoelectron spectrometer and a field emission scanning electron microscope,respectively.The corrosion resistance of bare NdFeB(S-Si)was analyzed by static full immersion corrosion test and electrochemical experiments.Effects of sputtering and thermal diffusion on the microstructure and corrosion resistance of the surface layer were studied.Results show that surface alloying layer can effectively improve the corrosion resistance of bare NdFeB with the optimized static total immersion corrosion test time in NdFeB(1S-Si)-800 of 36 h,which is much longer than that of the pristine NdFeB(less than 0.5 h).The E_(corr)of NdFeB(1S-Si)-800 positively shifts from-1.05 to-0.92 V,indicating that the corrosion tendency is obviously lower.The J_(corr)is1.45×10^(-6)A/cm^(2)which is 2 orders of magnitude lower than that of the pristine NdFeB(5.25×10^(-4)A/cm^(2)).The intergranular composite oxides existing in Nd-rich phase contribute to the enhancement of corrosion resistance of Si-surface-alloying NdFeB.
