Adsorbing tests between CN? and chalcopyrite or galena were conducted firstly, and then flotation tests of the twocyaniding minerals were investigated in butyl xanthate (BX) system. Results showed that the interaction...Adsorbing tests between CN? and chalcopyrite or galena were conducted firstly, and then flotation tests of the twocyaniding minerals were investigated in butyl xanthate (BX) system. Results showed that the interaction between CN? and the twomineral surfaces were both chemical adsorption and can be described by the Langmuir adsorption isotherm model. In the optimumcondition of pH 6.5 and 4.0 mg/L BX, the recovery of cyaniding chalcopyrite and galena reached 82.1% and 63.9%, respectively. BXimproved the hydrophobicity of the surfaces of the two minerals, although CN? reduced the contact angle on the surface of minerals.The inhibitory effect of CN? on chalcopyrite far outweighed galena. Electrostatic adsorption exists in the interaction between BX andthe surface of galena after cyanide treatment in the pH range of 4.2?8.4, while the interactions between BX and the surface ofchalcopyrite after cyanide treatment is chemical adsorption.展开更多
Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reducti...Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reduction temperature, reduction time, C/O mole ratio, and CaO content on the metallization degree and iron recovery were investigated in detail. Experimental results show that reduced products with the metallization degree of 95.82% could be produced under the optimal conditions （i.e., reduction temperature, 1250℃; reduction time, 50 min; C/O mole ratio, 2.0; and CaO content, 10wt%）. The magnetic concentrate containing 89.63wt% Fe with the iron recovery of 96.21% was obtained. According to the mineralogical and morphologic analysis, the iron minerals had been reduced and iron was mainly enriched into the metallic iron phase embedded in the slag matrix in the form of spherical particles. Apatite was also reduced to phosphorus, which partially migrated into the metallic iron phase.展开更多
The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperatur...The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperature pretreatment for enhancing the effect of iron enrichment and dephosphorization in the magnetization roasting–leaching process was studied by X-ray diffraction(XRD),vibration sample magnetometer(VSM),scanning electron microscopy and energy dispersive spectrometry(SEM–EDS).Compared with the process without high-temperature pretreatment,the iron grade of the magnetic separation concentrate after high-temperature pretreatment had increased by 0.98%,iron recovery rate had increased by 1.33%,and the phosphorus content in the leached residue had decreased by 0.12%.High-temperature pretreatment resulted in the dehydration and decomposition of hydroxyapatite,the dehydration of limonite and the thermal decomposition of siderite,which can produce pores and cracks and weaken the compactness of the ore,improve the magnetization characteristics of roasted ore,and strengthen the iron enrichment and dephosphorization during the magnetization roasting and leaching process.展开更多
The process of deep reduction and magnetic separation was proposed to enrich nickel and iron from laterite nickel ores.Results show that nickel-iron concentrates with nickel grade of 6.96%,nickel recovery of 94.06%,ir...The process of deep reduction and magnetic separation was proposed to enrich nickel and iron from laterite nickel ores.Results show that nickel-iron concentrates with nickel grade of 6.96%,nickel recovery of 94.06%,iron grade of 34.74%,and iron recovery of 80.44% could be obtained after magnetic separation under the conditions of reduction temperature of 1275℃,reduction time of 50 min,slag basicity of 1.0,carbon-containing coefficient of 2.5,and magnetic field strength of 72 kA/m.Reduction temperature and time affected the possibility of deep reduction and reaction progress.Slag basicity affected the composition of slag in burden and the spilling and enriching rate of nickel-iron from a matrix to form nickel-iron particles.Nickel-iron particles were generated,aggregated,and grew gradually in the reduction process.Nickel-iron particles can be effectively separated from gangue minerals by magnetic separation.展开更多
To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally re- duced in various reduction times at various reduction temperatures. The microstructure...To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally re- duced in various reduction times at various reduction temperatures. The microstructure and size of the metallic iron phase were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and a Bgrimm process mineralogy analyzer. In the results, the re- duced Fe separates from the ore and forms metallic iron protuberances, and then the subsequent reduced Fe diffuses to the protuberances and grows into metallic iron grains. Most of the metallic iron grains exist in the quasi-spherical shape and inlaid in the slag matrix. The cumula- tive frequency of metallic iron grain size is markedly influenced by both reduction time and temperature. With increasing reduction temperature and time, the grain size of metallic iron obviously increases. According to the classical grain growth equation, the growth kinetic parameters, i.e., time exponent, growth activation energy, and pre-exponential constant, are estimated to be 1.3759 ± 0.0374, 103.18 kJ·mol^-1, and 922.05, respec- tively. Using these calculated parameters, a growth model is established to describe the growth behavior of metallic iron grains.展开更多
To understand the migration mechanisms of phosphorus(P)during coal-based reduction,a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetic...To understand the migration mechanisms of phosphorus(P)during coal-based reduction,a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetics of P were investigated by a field-emission electron probe microanalyzer(FE-EPMA)and using the basic principle of solid phase mass transfer,respectively.Experimental results showed that the P transferred from the slag to the metallic phase during reduction,and the migration process could be divided into three stages:phosphorus diffusing from the slag to the metallic interface,the formation of Fe P compounds at the slag metal interface and P diffusing from the slag metal interface to the metallic interior.The reduction time and temperature significantly influenced the phosphorus content of the metallic and slag phases.The P content of the metallic phase increased with increasing reduction time and temperature,while that of the slag phase gradually decreased.The P diffusion constant and activation energy were determined and a migration kinetics model of P in coal-based reduction was proposed.P diffusion in the metallic phase was the controlling step of the P migration.展开更多
This study focuses on the reduction of phosphorus from high-phosphorus-content oolitic iron ore via coal-based reduction. The distribution behavior of phosphorus （i.e., the phosphorus content and the phosphorus distr...This study focuses on the reduction of phosphorus from high-phosphorus-content oolitic iron ore via coal-based reduction. The distribution behavior of phosphorus （i.e., the phosphorus content and the phosphorus distribution ratio in the metal, slag, and gas phases） during reduction was investigated in detail. Experimental results showed that the distribution behavior of phosphorus was strongly influenced by the reduction temperature, the reduction time, and the C/O molar ratio. A higher temperature and a longer reaction time were more favor-able for phosphorus reduction and enrichment in the metal phase. An increase in the C/O ratio improved phosphorus reduction but also hin-dered the mass transfer of the reduced phosphorus when the C/O ratio exceeded 2.0. According to scanning electron microscopy analysis, the iron ore was transformed from an integral structure to metal and slag fractions during the reduction process. Apatite in the ore was reduced to P, and the reduced P was mainly enriched in the metal phase. These results suggest that the proposed method may enable utilization of high-phosphorus-content oolitic iron ore resources.展开更多
The effects of crushing energy, ore hardness and particle size of cassiterite polymetallic sulphide ore and lead-zinc polymetallic sulphide ore on the crushing characteristics during impact crushing were investigated ...The effects of crushing energy, ore hardness and particle size of cassiterite polymetallic sulphide ore and lead-zinc polymetallic sulphide ore on the crushing characteristics during impact crushing were investigated by mineral liberation analyzer(MLA) and drop weight test. The results show that both ores contain pyrrhotite, sphalerite, jamesonite, gangue mica and quartz except cassiterite. Cassiterite is closely associated with sulphide and quartz to form aggregates, which are mixed with each other in the form of intergrowth or symbiotic disseminated fine grains. Cassiterite has a significant impact on ore crushing characteristics. Ore hardness is negatively correlated with the product of crushing parameters of A and b, i.e. A×b, the effect of crushing energy on crushing fineness is related to crushing parameters A and b, and the influence degree increases with the increase of A. The influence degree increases with the increase of b when crushing energy ECS is less than 1 kW·h/t, and the influence degree decreases with the increase of b when crushing energy ECS is greater than 1 kW·h/t. The impact of crushing energy on crushing fineness is greater than that of ore particle size when the crushing energy is lower;on the contrary, the impact of ore particle size on crushing fineness is greater than that of crushing energy when crushing energy is higher.展开更多
Sodium hexametaphosphate(SHMP)was used to minimize the adverse effect of serpentine for improving aschariterecovery.The effects of particle size and content of SHMP,and serpentine on ascharite flotation process were i...Sodium hexametaphosphate(SHMP)was used to minimize the adverse effect of serpentine for improving aschariterecovery.The effects of particle size and content of SHMP,and serpentine on ascharite flotation process were investigated throughflotation,zeta potential tests,FT-IR analysis,XPS analysis and DLVO theory.Particles interaction and mechanism of SHMP werealso discussed.It was found that aggregation between serpentine and ascharite particles easily happened,and the particle size ofserpentine had a profound impact on the ascharite recovery.In particular,the fine serpentine with size less than38μm had thegreatest contribution to the deterioration of ascharite flotation performance.After SHMP treatment,the adverse effect of serpentinewas significantly reduced.The mechanism of SHMP showed that it could alter the surface charges of serpentine and ascharite toprevent severe interparticle aggregation,which resulted in a well-dispersed pulp and benefited ascharite flotation process.Theadsorption of SHMP on serpentine was due to hydrogen bonding and chemical adsorption,resulting in the formation of complex onserpentine surface to decrease its floatability.展开更多
A high-voltage pulsed discharge(HVPD)pretreatment was used to strengthen the leaching effect of Carlin-type gold ore containing arsenic.Optimal results of the pretreatment experiments were obtained at the following op...A high-voltage pulsed discharge(HVPD)pretreatment was used to strengthen the leaching effect of Carlin-type gold ore containing arsenic.Optimal results of the pretreatment experiments were obtained at the following operating conditions:a spherical gap spacing of 20 mm,pulse number of 100,and voltage of 30 kV.The leaching rate of gold was increased by 15.65%via the HVPD pretreatment.The mass fraction of–0.5+0.35 mm and–0.35+0.1 mm was increased by 10.97%and 6.83%compared to the untreated samples,respectively,and the Au grade of–0.1 mm was increased by 22.84%.However,the superiority of the HVPD pretreatment would be weakened by prolonged grinding time.Scanning electron microscopy results indicated that the pretreated products presented as a melting state and then condensation,accompanying by some pore formation.More micro-cracks were generated at the interface of the ore and the original crack were expended via pulsed discharge pretreatment,with the contact area between the leaching reagent and ore increased,the leaching reaction rate enhanced and the leaching effect strengthened.展开更多
BACKGROUND Pancreatic mucinous cystic neoplasms(MCNs)represent one of the precursor lesions of pancreatic ductal adenocarcinoma,and their detection has been facilitated by advances in preoperative imaging.Due primaril...BACKGROUND Pancreatic mucinous cystic neoplasms(MCNs)represent one of the precursor lesions of pancreatic ductal adenocarcinoma,and their detection has been facilitated by advances in preoperative imaging.Due primarily to the rarity of MCNs,however,there is limited knowledge regarding the prognostic variables and high-risk factors for malignant transformation.A more comprehensive and nuanced approach is necessary to fill this gap and provide a basis for improved treatment decisions and patient outcomes.AIM To investigate the high-risk factors associated with malignant MCNs and to explore the prognostic factors of MCN with associated invasive carcinoma(MCNAIC).METHODS All cases of resected MCNs from a single high-volume institution between January 2012 and January 2022 were retrospectively reviewed.Only cases with ovarian-type stroma verified by progesterone receptor staining were included.Preoperative features,histological findings and postoperative course were documented.Multivariate logistic regression was employed to investigate variables related to malignancy.Survival analysis was performed using the Kaplan-Meier curve,and the prognostic factors were assessed to evaluate the postoperative course of patients with MCN-AIC.RESULTS Among the 48 patients,36 had benign MCNs,and 12 had malignant MCNs(1 high-grade atypical hyperplasia and 11 MCN-AIC).Age,tumour size,presence of solid components or mural nodules and pancreatic duct dilatation were identified as independent risk factors associated with malignancy.The follow-up period ranged from 12 mo to 120 mo,with a median overall survival of 58.2 mo.Only three patients with MCN-AIC died,and the 5-year survival rate was 70.1%.All 11 cases of MCN-AIC were stage I,and extracapsular invasion was identified as a prognostic factor for poorer outcomes.CONCLUSION The risk factors independently associated with malignant transformation of MCNs included age,tumour size,presence of solid components or mural nodules,and pancreatic duct dilatation.Our study also revealed that encapsulated invasion was a favourable prognostic factor in MCN-AIC patients.展开更多
To understand the formation and growth mechanism of the magnetite phase during the fluidized reduction of hematite, a high-purity hematite ore was isothermally reduced using a 20vol% CO 80vol% CO2 gas mixture in a mic...To understand the formation and growth mechanism of the magnetite phase during the fluidized reduction of hematite, a high-purity hematite ore was isothermally reduced using a 20vol% CO 80vol% CO2 gas mixture in a micro-fluidized bed to examine the process of the selective conversion of hematite to magnetite. The micro-structural characteristics of the magnetite phase were investigated using scanning electron microscopy (SEM) and the Brunauer, Emmett, and Teller (BET) method, and the thickness of the magnetite layer was measured and evaluated using statistical analysis. The experimental results showed that the fresh magnetite nuclei were dense needles of different lengths, and the original hematite grains became porous after complete reduction to the magnetite phase. The thickness of the mag- netite layer increased with an increase in reduction temperature and reduction time. The growth kinetics of the magnetite layer was investi- gated, and the value of the activation energy E was estimated to be 28.33 kJ/mol.展开更多
In order to ascertain the reaction behavior of rare earth minerals in coal-based reduction, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and energy dispersive spectroscopy（EDS） analyses were applie...In order to ascertain the reaction behavior of rare earth minerals in coal-based reduction, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and energy dispersive spectroscopy（EDS） analyses were applied to investigate the rare earth minerals in Bayan Obo.The occurrence state and regularity of rare earth elements were analyzed under different reduction time. The results reveal that rare earth elements in rare earth minerals exist in RE（CO3）F（bastnaesite） and REPO4（monazite）. In this research, at 1,498 K with a C/O molar ratio（i.e., molar ratio of fixed carbon in the coal to reducible oxygen in the ore） of2.5, rare earth minerals primarily decompose into RE2O3at5 min. When the time is extended to 10 min, solid-phase reactions occur among RE2O3, CaO, and SiO2, and the resultant is cerium wollastonite（CaO·2RE2O3·3SiO2）. At reaction time 〉20 min, rare earth elements mainly exist in cerium wollastonite（CaO·2RE2O3·3SiO2）, and the grain size varies in the range of 10–30 μm. The results show that coal-based reduction is efficient to recover rare earth minerals in reduced materials.展开更多
The comprehensive utilization of abundant high-boron iron concentrate is of particular significance to Chi- na, and the high-boron iron concentrate has not yet been utilized as a source for boron at an industrial scal...The comprehensive utilization of abundant high-boron iron concentrate is of particular significance to Chi- na, and the high-boron iron concentrate has not yet been utilized as a source for boron at an industrial scale due to its complex mineralogy and fine mineral dissemination. An innovative method was proposed for recovery of boron and iron from high-boron iron concentrate by reduction roasting and magnetic sepa- ration. The effects of reduction temperature and roasting time were investigated and their optimum condi- tions were determined. The mineralogical changes during roasting were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results showed that the pyrrhotite （FeS） contained in the high-boron iron concentrate and the new-formed FeS-Fe solid solution softened or melted at high temperatures owing to their low melting points, and then decreased the metallic iron ratio and accelerated the growth of metallic iron particles. Meanwhile, the magnetite and szaibelyite were converted into metal- lic iron and suanite, respectively. Consequently, boron was readily enriched into the non-magnetic product and the metallic iron was aggregated to the magnetic concentrate by magnetic separation. Boron recovery of 88.6% with corresponding B2O3 content of 14.5% and iron recovery of 95.1% with an iron grade of 92.7% were achieved when high-boron iron concentrate was reduced at 1 125℃ for 150 min. Besides, the boron reactivity of the boron-rich non-magnetic product was up to 80.8%.展开更多
基金Project(2012BAB08B03)supported by the National Key Technologies R&D Program of China
文摘Adsorbing tests between CN? and chalcopyrite or galena were conducted firstly, and then flotation tests of the twocyaniding minerals were investigated in butyl xanthate (BX) system. Results showed that the interaction between CN? and the twomineral surfaces were both chemical adsorption and can be described by the Langmuir adsorption isotherm model. In the optimumcondition of pH 6.5 and 4.0 mg/L BX, the recovery of cyaniding chalcopyrite and galena reached 82.1% and 63.9%, respectively. BXimproved the hydrophobicity of the surfaces of the two minerals, although CN? reduced the contact angle on the surface of minerals.The inhibitory effect of CN? on chalcopyrite far outweighed galena. Electrostatic adsorption exists in the interaction between BX andthe surface of galena after cyanide treatment in the pH range of 4.2?8.4, while the interactions between BX and the surface ofchalcopyrite after cyanide treatment is chemical adsorption.
基金supported by the National Natural Science Foundation of China(Nos.51134002 and 51074036)
文摘Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reduction temperature, reduction time, C/O mole ratio, and CaO content on the metallization degree and iron recovery were investigated in detail. Experimental results show that reduced products with the metallization degree of 95.82% could be produced under the optimal conditions （i.e., reduction temperature, 1250℃; reduction time, 50 min; C/O mole ratio, 2.0; and CaO content, 10wt%）. The magnetic concentrate containing 89.63wt% Fe with the iron recovery of 96.21% was obtained. According to the mineralogical and morphologic analysis, the iron minerals had been reduced and iron was mainly enriched into the metallic iron phase embedded in the slag matrix in the form of spherical particles. Apatite was also reduced to phosphorus, which partially migrated into the metallic iron phase.
基金the National Natural Science Foundation of China(Nos.51734005,51874071,and 51604063)the Fok Ying Tung Education Foundation for Young Teachers in the Higher Education Institutions of China(No.161045)+1 种基金the Liao Ning Revitalization Talents Program(No.XLYC1807111)the Fundamental Research Funds for the Central Universities of China(No.N180105030).
文摘The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperature pretreatment for enhancing the effect of iron enrichment and dephosphorization in the magnetization roasting–leaching process was studied by X-ray diffraction(XRD),vibration sample magnetometer(VSM),scanning electron microscopy and energy dispersive spectrometry(SEM–EDS).Compared with the process without high-temperature pretreatment,the iron grade of the magnetic separation concentrate after high-temperature pretreatment had increased by 0.98%,iron recovery rate had increased by 1.33%,and the phosphorus content in the leached residue had decreased by 0.12%.High-temperature pretreatment resulted in the dehydration and decomposition of hydroxyapatite,the dehydration of limonite and the thermal decomposition of siderite,which can produce pores and cracks and weaken the compactness of the ore,improve the magnetization characteristics of roasted ore,and strengthen the iron enrichment and dephosphorization during the magnetization roasting and leaching process.
基金Projects(51904058,51734005)supported by the National Natural Science Foundation of ChinaProject(2018YFC1901901902)supported by the National Key Research and Development Program of China
文摘The process of deep reduction and magnetic separation was proposed to enrich nickel and iron from laterite nickel ores.Results show that nickel-iron concentrates with nickel grade of 6.96%,nickel recovery of 94.06%,iron grade of 34.74%,and iron recovery of 80.44% could be obtained after magnetic separation under the conditions of reduction temperature of 1275℃,reduction time of 50 min,slag basicity of 1.0,carbon-containing coefficient of 2.5,and magnetic field strength of 72 kA/m.Reduction temperature and time affected the possibility of deep reduction and reaction progress.Slag basicity affected the composition of slag in burden and the spilling and enriching rate of nickel-iron from a matrix to form nickel-iron particles.Nickel-iron particles were generated,aggregated,and grew gradually in the reduction process.Nickel-iron particles can be effectively separated from gangue minerals by magnetic separation.
基金financially supported by the National Natural Science Foundation of China(Nos.51134002 and 51604063)the Fundamental Research Funds for the Central Universities(No.N140108001)
文摘To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally re- duced in various reduction times at various reduction temperatures. The microstructure and size of the metallic iron phase were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and a Bgrimm process mineralogy analyzer. In the results, the re- duced Fe separates from the ore and forms metallic iron protuberances, and then the subsequent reduced Fe diffuses to the protuberances and grows into metallic iron grains. Most of the metallic iron grains exist in the quasi-spherical shape and inlaid in the slag matrix. The cumula- tive frequency of metallic iron grain size is markedly influenced by both reduction time and temperature. With increasing reduction temperature and time, the grain size of metallic iron obviously increases. According to the classical grain growth equation, the growth kinetic parameters, i.e., time exponent, growth activation energy, and pre-exponential constant, are estimated to be 1.3759 ± 0.0374, 103.18 kJ·mol^-1, and 922.05, respec- tively. Using these calculated parameters, a growth model is established to describe the growth behavior of metallic iron grains.
基金financially supported by the National Natural Science Foundation of China (No.51604063)
文摘To understand the migration mechanisms of phosphorus(P)during coal-based reduction,a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetics of P were investigated by a field-emission electron probe microanalyzer(FE-EPMA)and using the basic principle of solid phase mass transfer,respectively.Experimental results showed that the P transferred from the slag to the metallic phase during reduction,and the migration process could be divided into three stages:phosphorus diffusing from the slag to the metallic interface,the formation of Fe P compounds at the slag metal interface and P diffusing from the slag metal interface to the metallic interior.The reduction time and temperature significantly influenced the phosphorus content of the metallic and slag phases.The P content of the metallic phase increased with increasing reduction time and temperature,while that of the slag phase gradually decreased.The P diffusion constant and activation energy were determined and a migration kinetics model of P in coal-based reduction was proposed.P diffusion in the metallic phase was the controlling step of the P migration.
基金financially supported by the National Natural Science Foundation of China(No.51134002)the Fundamental Research Funds for the Central Universi-ties of China(No.N120601004)
文摘This study focuses on the reduction of phosphorus from high-phosphorus-content oolitic iron ore via coal-based reduction. The distribution behavior of phosphorus （i.e., the phosphorus content and the phosphorus distribution ratio in the metal, slag, and gas phases） during reduction was investigated in detail. Experimental results showed that the distribution behavior of phosphorus was strongly influenced by the reduction temperature, the reduction time, and the C/O molar ratio. A higher temperature and a longer reaction time were more favor-able for phosphorus reduction and enrichment in the metal phase. An increase in the C/O ratio improved phosphorus reduction but also hin-dered the mass transfer of the reduced phosphorus when the C/O ratio exceeded 2.0. According to scanning electron microscopy analysis, the iron ore was transformed from an integral structure to metal and slag fractions during the reduction process. Apatite in the ore was reduced to P, and the reduced P was mainly enriched in the metal phase. These results suggest that the proposed method may enable utilization of high-phosphorus-content oolitic iron ore resources.
基金Projects(51874105,51674064,51734005)supported by the National Natural Science Foundation of ChinaProject(2018GXNSFAA281204)supported by the Guangxi Natural Science Foundation,China
文摘The effects of crushing energy, ore hardness and particle size of cassiterite polymetallic sulphide ore and lead-zinc polymetallic sulphide ore on the crushing characteristics during impact crushing were investigated by mineral liberation analyzer(MLA) and drop weight test. The results show that both ores contain pyrrhotite, sphalerite, jamesonite, gangue mica and quartz except cassiterite. Cassiterite is closely associated with sulphide and quartz to form aggregates, which are mixed with each other in the form of intergrowth or symbiotic disseminated fine grains. Cassiterite has a significant impact on ore crushing characteristics. Ore hardness is negatively correlated with the product of crushing parameters of A and b, i.e. A×b, the effect of crushing energy on crushing fineness is related to crushing parameters A and b, and the influence degree increases with the increase of A. The influence degree increases with the increase of b when crushing energy ECS is less than 1 kW·h/t, and the influence degree decreases with the increase of b when crushing energy ECS is greater than 1 kW·h/t. The impact of crushing energy on crushing fineness is greater than that of ore particle size when the crushing energy is lower;on the contrary, the impact of ore particle size on crushing fineness is greater than that of crushing energy when crushing energy is higher.
基金Project(51204033) supported by the National Natural Science Foundation of ChinaProject(L2014088) supported by Liaoning Provincial Education Department of China
文摘Sodium hexametaphosphate(SHMP)was used to minimize the adverse effect of serpentine for improving aschariterecovery.The effects of particle size and content of SHMP,and serpentine on ascharite flotation process were investigated throughflotation,zeta potential tests,FT-IR analysis,XPS analysis and DLVO theory.Particles interaction and mechanism of SHMP werealso discussed.It was found that aggregation between serpentine and ascharite particles easily happened,and the particle size ofserpentine had a profound impact on the ascharite recovery.In particular,the fine serpentine with size less than38μm had thegreatest contribution to the deterioration of ascharite flotation performance.After SHMP treatment,the adverse effect of serpentinewas significantly reduced.The mechanism of SHMP showed that it could alter the surface charges of serpentine and ascharite toprevent severe interparticle aggregation,which resulted in a well-dispersed pulp and benefited ascharite flotation process.Theadsorption of SHMP on serpentine was due to hydrogen bonding and chemical adsorption,resulting in the formation of complex onserpentine surface to decrease its floatability.
基金This work was financially supported by the National Natural Science Foundation of China(No.51974063)the Fundamental Research Funds for the Central Universities,China(No.N180104016).
文摘A high-voltage pulsed discharge(HVPD)pretreatment was used to strengthen the leaching effect of Carlin-type gold ore containing arsenic.Optimal results of the pretreatment experiments were obtained at the following operating conditions:a spherical gap spacing of 20 mm,pulse number of 100,and voltage of 30 kV.The leaching rate of gold was increased by 15.65%via the HVPD pretreatment.The mass fraction of–0.5+0.35 mm and–0.35+0.1 mm was increased by 10.97%and 6.83%compared to the untreated samples,respectively,and the Au grade of–0.1 mm was increased by 22.84%.However,the superiority of the HVPD pretreatment would be weakened by prolonged grinding time.Scanning electron microscopy results indicated that the pretreated products presented as a melting state and then condensation,accompanying by some pore formation.More micro-cracks were generated at the interface of the ore and the original crack were expended via pulsed discharge pretreatment,with the contact area between the leaching reagent and ore increased,the leaching reaction rate enhanced and the leaching effect strengthened.
基金Supported by the Natural Science Key Project in Universities of Anhui Province,No.KJ2021A0701Natural Science Key Project of Bengbu Medical College,No.2020byzd030Postgraduate Scientific Research Innovation Program of the Bengbu Medical College,No.Byycx22016.
文摘BACKGROUND Pancreatic mucinous cystic neoplasms(MCNs)represent one of the precursor lesions of pancreatic ductal adenocarcinoma,and their detection has been facilitated by advances in preoperative imaging.Due primarily to the rarity of MCNs,however,there is limited knowledge regarding the prognostic variables and high-risk factors for malignant transformation.A more comprehensive and nuanced approach is necessary to fill this gap and provide a basis for improved treatment decisions and patient outcomes.AIM To investigate the high-risk factors associated with malignant MCNs and to explore the prognostic factors of MCN with associated invasive carcinoma(MCNAIC).METHODS All cases of resected MCNs from a single high-volume institution between January 2012 and January 2022 were retrospectively reviewed.Only cases with ovarian-type stroma verified by progesterone receptor staining were included.Preoperative features,histological findings and postoperative course were documented.Multivariate logistic regression was employed to investigate variables related to malignancy.Survival analysis was performed using the Kaplan-Meier curve,and the prognostic factors were assessed to evaluate the postoperative course of patients with MCN-AIC.RESULTS Among the 48 patients,36 had benign MCNs,and 12 had malignant MCNs(1 high-grade atypical hyperplasia and 11 MCN-AIC).Age,tumour size,presence of solid components or mural nodules and pancreatic duct dilatation were identified as independent risk factors associated with malignancy.The follow-up period ranged from 12 mo to 120 mo,with a median overall survival of 58.2 mo.Only three patients with MCN-AIC died,and the 5-year survival rate was 70.1%.All 11 cases of MCN-AIC were stage I,and extracapsular invasion was identified as a prognostic factor for poorer outcomes.CONCLUSION The risk factors independently associated with malignant transformation of MCNs included age,tumour size,presence of solid components or mural nodules,and pancreatic duct dilatation.Our study also revealed that encapsulated invasion was a favourable prognostic factor in MCN-AIC patients.
基金financially supported by the National Science Foundation of China (Nos. 51734005 and 51674065)the China Postdoctoral Science Foundation (No. 2018M631812)Open Foundation of State Key Laboratory of Mineral Processing, Beijing General Research Institute of Mining & Metallurgy Group, China (No. BGRIMM-KJSKL-2019-09)
文摘To understand the formation and growth mechanism of the magnetite phase during the fluidized reduction of hematite, a high-purity hematite ore was isothermally reduced using a 20vol% CO 80vol% CO2 gas mixture in a micro-fluidized bed to examine the process of the selective conversion of hematite to magnetite. The micro-structural characteristics of the magnetite phase were investigated using scanning electron microscopy (SEM) and the Brunauer, Emmett, and Teller (BET) method, and the thickness of the magnetite layer was measured and evaluated using statistical analysis. The experimental results showed that the fresh magnetite nuclei were dense needles of different lengths, and the original hematite grains became porous after complete reduction to the magnetite phase. The thickness of the mag- netite layer increased with an increase in reduction temperature and reduction time. The growth kinetics of the magnetite layer was investi- gated, and the value of the activation energy E was estimated to be 28.33 kJ/mol.
基金financially supported by the National Natural Science Foundation of China (Nos. 51204033 and 51134002)
文摘In order to ascertain the reaction behavior of rare earth minerals in coal-based reduction, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and energy dispersive spectroscopy（EDS） analyses were applied to investigate the rare earth minerals in Bayan Obo.The occurrence state and regularity of rare earth elements were analyzed under different reduction time. The results reveal that rare earth elements in rare earth minerals exist in RE（CO3）F（bastnaesite） and REPO4（monazite）. In this research, at 1,498 K with a C/O molar ratio（i.e., molar ratio of fixed carbon in the coal to reducible oxygen in the ore） of2.5, rare earth minerals primarily decompose into RE2O3at5 min. When the time is extended to 10 min, solid-phase reactions occur among RE2O3, CaO, and SiO2, and the resultant is cerium wollastonite（CaO·2RE2O3·3SiO2）. At reaction time 〉20 min, rare earth elements mainly exist in cerium wollastonite（CaO·2RE2O3·3SiO2）, and the grain size varies in the range of 10–30 μm. The results show that coal-based reduction is efficient to recover rare earth minerals in reduced materials.
基金the financial support from the National Natural Science Foundation of China (51134002)the Fundamental Research Funds for the Central Universities of China (N140108001 and N150106003)
文摘The comprehensive utilization of abundant high-boron iron concentrate is of particular significance to Chi- na, and the high-boron iron concentrate has not yet been utilized as a source for boron at an industrial scale due to its complex mineralogy and fine mineral dissemination. An innovative method was proposed for recovery of boron and iron from high-boron iron concentrate by reduction roasting and magnetic sepa- ration. The effects of reduction temperature and roasting time were investigated and their optimum condi- tions were determined. The mineralogical changes during roasting were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results showed that the pyrrhotite （FeS） contained in the high-boron iron concentrate and the new-formed FeS-Fe solid solution softened or melted at high temperatures owing to their low melting points, and then decreased the metallic iron ratio and accelerated the growth of metallic iron particles. Meanwhile, the magnetite and szaibelyite were converted into metal- lic iron and suanite, respectively. Consequently, boron was readily enriched into the non-magnetic product and the metallic iron was aggregated to the magnetic concentrate by magnetic separation. Boron recovery of 88.6% with corresponding B2O3 content of 14.5% and iron recovery of 95.1% with an iron grade of 92.7% were achieved when high-boron iron concentrate was reduced at 1 125℃ for 150 min. Besides, the boron reactivity of the boron-rich non-magnetic product was up to 80.8%.
