This paper reviews the research progress of pressure ammonia leaching technology in the extrac-tion of nickel,cobalt,molybdenum and other metals,as well as the comprehensive utilization of secondary resources.The technology exhibits remarkable advantages in improving metal recovery,reducing environ-mental pollution,and enhancing resource utilization efficiency,thus playing a significant role in promoting green metallurgy and the sustainable utilization of resources.The main challenges faced in the practical ap-plication of pressure ammonia leaching technology are also discussed,and its future development trends are prospected.This paper aims to provide a theoretical reference and practical guidance for the further optimi-zation and upgrading of this technology,its industrial promotion,and the green and efficient development of complex nonferrous metal resources.
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High-purity cerium oxide is widely used in high-end sectors such as electronics and optics.There-fore,the accurate determination of its lanthanum content is essential for ensuring product quality control and improving the efficiency of comprehensive resource utilization.To address the issue of insufficient pre-cision in the determination of lanthanum content in high-purity cerium oxide by inductively coupled plasma mass spectrometry(ICP-MS),this paper systematically analyzes the primary influencing factors,including the complexity of the sample composition,environmental interferences(temperature and relative humidi-ty),and the settings of instrumental parameters(RF power and carrier gas flow rate).Based on this analy-sis,corresponding optimization strategies are proposed:Sample pretreatment using ion exchange chroma-tography or extraction to reduce impurity interference and enrich lanthanum,the application of an environ-mental variable correction model to mitigate the effects of temperature and relative humidity fluctuations on the determination results,controlling the experimental environmental conditions within a temperature range of 20~25℃and relative humidity of 40%~60%,and optimizing the ICP-MS instrument operating parameters with an RF power of 1350~1400 W and a carrier gas flow rate of 0.81.0 L/min.Under the optimal conditions(ambient temperature of 20℃,relative humidity of 40%,RF power of 1400 W,and carrier gas flow rate of 1.0 L/min),the detection limit for lanthanum in the high-purity cerium oxide ma-trix solution reaches as low as 0.01μg/L,and the relative standard deviation(RSD)is reduced to 1.65%.This significantly enhances the accuracy and reliability of the measurement results,meeting the require-ments for the precise determination of trace lanthanum in high-purity cerium oxide.
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A experimental study on comprehensive recovery of spodumene and associated tantalite-columbite from a granitic pegmatite-type spodumene ore from Xinjiang with a Li2O grade of 1.66%,Ta2O5 grade of 0.0137%,and Nb2O5 grade of 0.0148%was carried out.A stepwise recovery process combining gravity separation,flotation,and magnetic-gravity separation was adopted.Coarse-grained spodumene was first re-covered by dense medium separation.Rougher flotation conditions for the gravity separation product were then optimized,and closed-circuit tests of dense medium separation and flotation with one roughing,two scavengings and three cleanings were conducted.Finally,associated tantalum and niobium were recovered from lithium concentrate using a combined process of high-intensity magnetic separation and shaking table gravity separation.The results show that under the dense medium separation conditions with the raw ore crushed to-6 mm and a dense medium suspension density of 2.45 g/cm3,and the rougher flotation condi-tions including a pulp density of 30%,a grinding fineness of 76.30%passing-0.074 mm,and reagent dosages of 500 g CaCl2,2000 g SG,1200 g NaOH,800 g Na2CO3,and 1200 g ZGP-series collec-tors(800 g ZGP-1+400 g ZGP-3),a lithium concentrate with Li2O grade of 5.79%and recovery of 30.73%is obtained via the gravity-flotation closed-circuit process.The recoveries of associated Nb2O5 and Ta2O5 in the lithium concentrate reach 92.03%and 94.07%,respectively.Subsequently,the mixed lithium concentrate from the gravity-flotation process was treated by 20 kOe high-intensity magnetic separation combined with two-stage shaking table gravity separation,producing a tantalum-niobium concentrate with Nb2O5 grade of 14.75%(recovery 77.31%)and Ta2O5 grade of 16.03%(recovery 80.94%).The pro-posed process realizes the comprehensive recovery of lithium,tantalum and niobium resources.
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During high-temperature,high-reduction deformation,beryllium is susceptible to contamination by free impurity elements originating from the A3 and S45 steels used for pack rolling and superimposed rolling.Specifically,Fe and Si primarily reside on the surface layer of the deformed beryllium through ad-sorption,while Mn and C accumulate via diffusion.This study investigated the influence law of free impuri-ty content on the surface strength,hardness,and plasticity of deformed beryllium.Effective control of Fe/Si and Mn/C impurities was achieved through weak acid cleaning and ultrasonic cleaning,respectively.The results indicate that an increase in free impurity content significantly enhances surface strength and hard-ness but reduces elongation after fracture.As point defects,free impurities hinder dislocation movement and promote excessive grain refinement,which strengthens the material while simultaneously impairing its plasticity.Weak acid cleaning effectively reduces Fe and Si impurities,whereas ultrasonic cleaning signifi-cantly decreases Mn and C impurities.This research confirms that rational control of the free impurity con-tent in deformed bery-llium surface can achieve a balance between strength,hardness,and plasticity,provi-ding a theoretical and technical foundation for the preparation of high-performance beryllium materials.
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To address the emulsification risk during aqueous two-phase extraction caused by high iron con-centration(Fe3+>5 g/L)in the acidic leachate of red mud,the jarosite method was employed for selective iron removal.Pretreatment of 100 mL acidic leachate via potassium sulfate precipitation was conducted.Under the optimized conditions(precipitation time of 60 min,precipitation temperature of 100℃,leachate pH of 2,and K2SO4 seed crystal addition of 3.5 g),an iron precipitation rate of 53.19%is achieved.The Fe3+concentration in the filtrate is effectively reduced to below 5 g/L,eliminating the emulsification risk.Subsequently,an aqueous two-phase system(ATPS)composed of polyethylene glycol 2000(PEG2000)and sodium sulfate was constructed to extract vanadium from the iron-removed solution.The effects of ex-traction time,iron-removed solution pH,charge regulator AC1815,and extraction temperature on vanadium extraction rate were systematically investigated.The extraction mechanism was explored through FTIR spectroscopy and Zeta potential.The results indicate that apart from Fe3+,coexisting ions exhibit negligible interference with vanadium extraction.Under the optimal conditions of an extraction time of 20 min,an iron-removed solution pH of 2,an extraction temperature of 20℃,and the addition of one drop of AC1815,the vanadium extraction rate reaches 85.24%.The protonated charge regulator combines with polyvanada-te anions through electrostatic attraction,thereby driving their transfer into the PEG2000 phase.This process successfully achieves vanadium-iron separation in the acidic leachate of red mud and efficient vana-dium extraction in the ATPS,providing theoretical support and a technical pathway for the industrial re-source utilization of red mud.
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FeCoCrNiMo0.75 high-entropy alloys prepared by vacuum arc melting were subjected to laser sur-face remelting modification treatment.The effects of different laser powers(300~1500 W)on the remel-ted microstructure,hardness,and friction and wear properties of FeCoCrNiMo0.75 alloy were investigated using XRD,SEM-EDS,a microhardness tester,and a reciprocating friction and wear tester.The results show that the thickness of the remelted layer increases with increasing laser power.The microstructure of the alloy without remelting treatment is mainly composed of FCC,σphase andμphase.After remelting at low power(300~600 W),the phase composition does not change significantly.When the laser power is in-creased to 900~1500 W,theμphase in the remelted microstructure disappears.Laser remelting can signi-ficantly refine the eutectic microstructure of the alloy and improve its surface hardness and friction and wear properties.Among them,FeCoCrNiMo0.75 high-entropy alloy remelted at 600 W laser power has the optimal comprehensive performance,with the highest average hardness of the remelted layer(573 HV0.2).In addition,its friction coefficient,surface roughness,and volumetric wear rate are all the lowest,and the volumetric wear rate is reduced by 85.5%compared with the alloy without remelting.In terms of wear mechanisms,the room-temperature wear mechanism of the alloy without remelting is mainly abrasive wear and fatigue wear.However,after the alloy is subjected to laser surface remelting treatment,its wear mecha-nism is mainly abrasive wear.
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During high-temperature,high-reduction deformation,beryllium is susceptible to contamination by free impurity elements originating from the A3 and S45 steels used for pack rolling and superimposed rolling.Specifically,Fe and Si primarily reside on the surface layer of the deformed beryllium through ad-sorption,while Mn and C accumulate via diffusion.This study investigated the influence law of free impuri-ty content on the surface strength,hardness,and plasticity of deformed beryllium.Effective control of Fe/Si and Mn/C impurities was achieved through weak acid cleaning and ultrasonic cleaning,respectively.The results indicate that an increase in free impurity content significantly enhances surface strength and hard-ness but reduces elongation after fracture.As point defects,free impurities hinder dislocation movement and promote excessive grain refinement,which strengthens the material while simultaneously impairing its plasticity.Weak acid cleaning effectively reduces Fe and Si impurities,whereas ultrasonic cleaning signifi-cantly decreases Mn and C impurities.This research confirms that rational control of the free impurity con-tent in deformed bery-llium surface can achieve a balance between strength,hardness,and plasticity,provi-ding a theoretical and technical foundation for the preparation of high-performance beryllium materials.
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To address the emulsification risk during aqueous two-phase extraction caused by high iron con-centration(Fe3+>5 g/L)in the acidic leachate of red mud,the jarosite method was employed for selective iron removal.Pretreatment of 100 mL acidic leachate via potassium sulfate precipitation was conducted.Under the optimized conditions(precipitation time of 60 min,precipitation temperature of 100℃,leachate pH of 2,and K2SO4 seed crystal addition of 3.5 g),an iron precipitation rate of 53.19%is achieved.The Fe3+concentration in the filtrate is effectively reduced to below 5 g/L,eliminating the emulsification risk.Subsequently,an aqueous two-phase system(ATPS)composed of polyethylene glycol 2000(PEG2000)and sodium sulfate was constructed to extract vanadium from the iron-removed solution.The effects of ex-traction time,iron-removed solution pH,charge regulator AC1815,and extraction temperature on vanadium extraction rate were systematically investigated.The extraction mechanism was explored through FTIR spectroscopy and Zeta potential.The results indicate that apart from Fe3+,coexisting ions exhibit negligible interference with vanadium extraction.Under the optimal conditions of an extraction time of 20 min,an iron-removed solution pH of 2,an extraction temperature of 20℃,and the addition of one drop of AC1815,the vanadium extraction rate reaches 85.24%.The protonated charge regulator combines with polyvanada-te anions through electrostatic attraction,thereby driving their transfer into the PEG2000 phase.This process successfully achieves vanadium-iron separation in the acidic leachate of red mud and efficient vana-dium extraction in the ATPS,providing theoretical support and a technical pathway for the industrial re-source utilization of red mud.
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FeCoCrNiMo0.75 high-entropy alloys prepared by vacuum arc melting were subjected to laser sur-face remelting modification treatment.The effects of different laser powers(300~1500 W)on the remel-ted microstructure,hardness,and friction and wear properties of FeCoCrNiMo0.75 alloy were investigated using XRD,SEM-EDS,a microhardness tester,and a reciprocating friction and wear tester.The results show that the thickness of the remelted layer increases with increasing laser power.The microstructure of the alloy without remelting treatment is mainly composed of FCC,σphase andμphase.After remelting at low power(300~600 W),the phase composition does not change significantly.When the laser power is in-creased to 900~1500 W,theμphase in the remelted microstructure disappears.Laser remelting can signi-ficantly refine the eutectic microstructure of the alloy and improve its surface hardness and friction and wear properties.Among them,FeCoCrNiMo0.75 high-entropy alloy remelted at 600 W laser power has the optimal comprehensive performance,with the highest average hardness of the remelted layer(573 HV0.2).In addition,its friction coefficient,surface roughness,and volumetric wear rate are all the lowest,and the volumetric wear rate is reduced by 85.5%compared with the alloy without remelting.In terms of wear mechanisms,the room-temperature wear mechanism of the alloy without remelting is mainly abrasive wear and fatigue wear.However,after the alloy is subjected to laser surface remelting treatment,its wear mecha-nism is mainly abrasive wear.
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