Stemming from the high costs and environmental pollution associated with the use of sodium sulfide in the separation and extraction processes of molybdenum bismuth ore,calcium hypochlorite was introduced as a substitu...Stemming from the high costs and environmental pollution associated with the use of sodium sulfide in the separation and extraction processes of molybdenum bismuth ore,calcium hypochlorite was introduced as a substitute to facilitate the cleaner production of low-grade molybdenum bismuth ore in this study.The effects of calcium hypochlorite on molybdenite,bismuthinite,and pyrite were investigated through micro-flotation,flotation kinetics,batch flotation,Fourier transform infrared(FTIR)spectra,scanning electron microscopy energy dispersion spectra(SEM-EDS),and inductively coupled plasma-optical emission spectra(ICP-OES).The flotation tests results showed that calcium hypochlorite could selectively depress bismuthinite and pyrite.In comparison to sodium sulfide,calcium hypochlorite not only improved the flotation indicators for molybdenum and bismuth concentrates but also reduced the dosage of flotation reagents.Moreover,the chemical oxygen demand(COD)of tailings wastewater significantly decreased when using calcium hypochlorite as a depressant.Mechanism research revealed that the use of calcium hypochlorite as a depressant led to BiOCl precipitation on bismuthinite,which hindered the attachment of the collector.In summary,calcium hypochlorite serves as a more efficient and environmentally friendly depressant compared to sodium sulfide in the industrial production processes of low-grade molybdenum bismuth ore.展开更多
The similar floatabilities of calcium minerals and the huge difference between scheelite and wolframite have resulted in difficulties during their separation by flotation in Shizhuyuan Mine. In this study, novel colle...The similar floatabilities of calcium minerals and the huge difference between scheelite and wolframite have resulted in difficulties during their separation by flotation in Shizhuyuan Mine. In this study, novel collectors, lead complexes of benzohydroxamic acid（Pb-BHA）,were introduced to modify the surface properties of scheelite and wolframite, thereby effectively and selectively improving floatability. The Pb-BHA complexes are found to be selective for the separation of scheelite and calcium minerals with little use of depressants and enable the synchronous flotation of scheelite and wolframite.Hence, a novel flotation process was developed for the recovery of tungsten minerals. The process is simplified greatly, and the recovery is improved by almost 10%.Removing or decreasing the amount of water glass contributes to the improvement of tungsten and fluorite recovery and the circulation of water and reagents, which benefits the environment.展开更多
Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational d...Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest,deciduous broadleaved forest,coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition,elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16 S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites,and Subdivision 6 has the highest number of detectable operational taxonomic units（OTUs）. A significant single peak distribution pattern（P 〈 0.05） between the OTU number and the elevation was observed. The Jaccard and Bray–Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased（P 〈 0.01） with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship（P 〈 0.01） with different soil enzymes. Therefore,soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH,soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure.展开更多
In the newly developed oxygen-enriched bottom-blowing copper smelting process(also known as the SKS copper smelting process), Cu loss in slag is one of the most concerning issues. This paper presents our research resu...In the newly developed oxygen-enriched bottom-blowing copper smelting process(also known as the SKS copper smelting process), Cu loss in slag is one of the most concerning issues. This paper presents our research results concerning the relationship between the Cu content of the matte and slag in the SKS process; the results are based on actual industrial production in the Dongying Fangyuan copper smelter. The results show that the matte grade strongly influences Cu losses in slag. The dissolved and entrained losses account for 10%–20% and 80%–90% of the total SKS industrial Cu losses in slag, respectively. With increasing matte grade, the dissolved and entrained Cu losses in the SKS slag both increase continuously. When the matte grade is greater than 68%, the content of Cu in the smelting slag increases much more dramatically. To obtain a high direct recovery of copper, the matte grade should be less than 75% in industrial SKS copper production.展开更多
Lime(CaO)and sodium humate(NaHA)were used as the combined depressant for arsenopyrite pre-treated by CuSO_(4) and butyl xanthate.Micro-flotation tests show that the combined depressant CaO and NaHA achieved the select...Lime(CaO)and sodium humate(NaHA)were used as the combined depressant for arsenopyrite pre-treated by CuSO_(4) and butyl xanthate.Micro-flotation tests show that the combined depressant CaO and NaHA achieved the selective depression of arsenopyrite.Closed-circuit lab-scale test results indicate that the synergistic effect of CaO+NaHA achieved a satisfactory flotation separation of sphalerite and arsenopyrite,for which the Zn grade and recovery of Zn concentrate were 51.21%and 92.21%,respectively.Contact angle measurements,adsorption amount measurements and X-ray photoelectron spectroscopy analysis indicate that the dissolved calcium species(mainly as Ca(2+))were adsorbed on the mineral surfaces,thereby promoting NaHA adsorption.Moreover,the surface of the arsenopyrite absorbed more amount of calcium species and NaHA than that of the sphalerite,thereby accounting for the strong hydrophilic surface of arsenopyrite.The adsorption of NaHA on arsenopyrite was mainly chemical adsorption through its carboxyl groups and Ca atoms,whereas that on sphalerite surface was relatively weak.展开更多
The composition of a collector directly affects its collecting performance in mineral flotation.In this study,three vegetable oils were used as the collectors,the flotation performance of scheelite and the differentia...The composition of a collector directly affects its collecting performance in mineral flotation.In this study,three vegetable oils were used as the collectors,the flotation performance of scheelite and the differential analysis were studied through flotation experiments,zeta potential,contact angle measurement and Fourier transform infrared spectrum(FTIR)analysis.Flotation results show that the recovery of scheelite increases in the order of oleic acid<rapeseed oil<rice bran oil<soybean oil,especially in the pH range of 5-8.The distinction in the scheelite recovery is due to the different compositions of these collectors.The addition of LA,LNA and PA(<5%)can increase the recovery of scheelite with OA,but the addition of SA deteriorates the scheelite flotation.Results of zeta potential,contact angle measurement and FTIR analysis indicate that the collector adsorption on scheelite surface is enhanced when using the three vegetable oils.For the raw ore with 0.086%WO3,a rough concentrate containing 1.423%WO3 with the recovery of 84.22%is obtained using soybean oil as the collector.展开更多
Flotation experiments were performed to investigate the separation of muscovite and quartz in the presence of dodecylamine(DDA), tallow amine(TTA) and dodecyltrimethylammonium bromide(DTAC). The adsorption mechanisms ...Flotation experiments were performed to investigate the separation of muscovite and quartz in the presence of dodecylamine(DDA), tallow amine(TTA) and dodecyltrimethylammonium bromide(DTAC). The adsorption mechanisms of these three kinds of amines on muscovite and quartz were studied by FT-IR spectrum analysis, contact angle measurement and molecular dynamics(MD) simulation. The results reveal that the separation of muscovite from quartz is feasible at strong acid pulp condition using amine collectors. TTA and DTAC show poorer collecting ability for flotation of the two minerals compared with DDA. Physical adsorption is found to be the main adsorption module of amine collectors on muscovite and quartz by FT-IR analysis. MD simulation results show a strong physical adsorption ability of DDA+ cation on muscovite and quartz(muscovite(001):-117.31 kJ/mol, quartz(100):-89.43 kJ/mol), while neutral DDA molecular can hardly absorb onto the surface of these two minerals. These findings provide a novel explanation for the flotation mechanism from the perspective of MD simulation.展开更多
The influence of pulp temperature on the floatability and adsorption behavior of fine wolframite with sodium oleate was investigated by microflotation experiments, electric conductivity tests, adsorption measurements,...The influence of pulp temperature on the floatability and adsorption behavior of fine wolframite with sodium oleate was investigated by microflotation experiments, electric conductivity tests, adsorption measurements, and FT-IR analysis. Microflotation results show that fine wolframite with sodium oleate exhibits a good floatability at pH 8–9. Electric conductivity tests indicate that the high temperature enhances the ionization degree and electric mobility of oleate species, then the flotation recovery of fine wolframite and the adsorption amount of sodium oleate are observed to increase with the rise in pulp temperature. The results of adsorption experiments are found to meet Freundlich isotherms successfully, and the isosteric enthalpy （ΔH^Θ） is in conformity with the chemical bonding. The changes in FT-IR analysis provide sufficient evidence that sodium oleate interacts with the metal cations of wolframite surface, and the increase in pulp temperature clearly promotes the chemisorption intensity. These findings will be beneficial to strengthen the flotation behavior of fine wolframite.展开更多
Flotation behavior and adsorption mechanism of octyl hydroxamic acid(OHA)on wolframite were investigated through flotation experiments,adsorption tests,zeta-potential measurements,infrared spectroscopy and solution ch...Flotation behavior and adsorption mechanism of octyl hydroxamic acid(OHA)on wolframite were investigated through flotation experiments,adsorption tests,zeta-potential measurements,infrared spectroscopy and solution chemistry calculations.Results of flotation and adsorption experiments show that the maximum values of flotation recovery and adsorption capacity occur around p H 9.In term of the solution chemistry calculations,the concentration of metal hydroxamate is greater than that of metal tungstate and metal hydroxyl,and metal hydroxamate compounds are identified to be the main species on wolframite surface at p H region of 8-10,contributing to the increase of OHA adsorption and flotation performance.Results of zeta-potential and IR spectra demonstrate that OHA adsorbs onto wolframite surface by chemisorptions.Hydroxamate ions can bond with Mn_2+/Fe_2+cations of wolframite surface,forming metal hydroxamate compounds,which is a key factor in inducing the hydrophobicity of wolframite under the conditions of maximum flotation.展开更多
A new process for manufacturing organically compounded bentonite was devcloped successfully based on the organic intercalation andlayered structure of bentonitc.The main steps in the proposed process included wet sodi...A new process for manufacturing organically compounded bentonite was devcloped successfully based on the organic intercalation andlayered structure of bentonitc.The main steps in the proposed process included wet sodium activation of bentonite ore,organic com-pounding and high-pressure roll grinding.The optimum procedure is recommended as follows:5 mass%of sodium carbonate powderand 30 wt.%water are added to activate the bentonite ore for 24 h to prepare activated bentonice;0.5 wt.%of organic molecules are adiedinto the activated bentonite for organic compounding for 12 h:then,the high-pressure rollgrinding is followed to treat the organicallycompounded bentonice;:and finally,drying and fine prinding are performed for prenaring the final organically compounded bentoniteprodiuct with 10 wt.%moisture and 98% passing 0.074 mm.The obtained organically compounded bentonite was characterized usingan X-ray diffractometer,a scanning electron microscope and anX-ray photoelectron spectrometer.To confirm the effect of organicallycompounded bentonite on green balls,the pelletizing tests were carried out.The rexsults showed that high-pressure roll grinding can notonly enhance the ability of the crystal layer to hold the combined water.but also strengthen the intercalation compounding of the organicadditive,which is beneficial for the formation of a fiber-interlaced structure of the organically compounded bentonite and improvesthe quality index of the bentonite itself.Also,the organically compounded bentonite is helpiul to improve the indexes of green balls.展开更多
The minerals jamesonite and marmatite have similar surface properties.Separating them using a flotation method is inefficient.For separation of lead and zinc the lead mineral is generally floated preferentially to the...The minerals jamesonite and marmatite have similar surface properties.Separating them using a flotation method is inefficient.For separation of lead and zinc the lead mineral is generally floated preferentially to the zinc mineral,which appears in the sinks.In this study a new of collector,2-aminothiophenol,is introduced that can float a zinc mineral,as a product entrapped in foam,preferentially.Single mineral flotation tests revealed that 2-aminothiophenol has good selectivity for flotation of marmatite. An artificial mixture of minerals used in a flotation test showed that 2-aminothiophenol can effectively separate marmatite from jamesonite.A product assaying at 45.06%Zn and 4.06%Pb was produced.FTIR spectra were employed to probe the adsorption mechanism of 2-aminothiophenol onto marmatite.The results indicate that adsorption of 2-aminothiophenol onto jamesonite and marmatite were,respectively,physical adsorption and chemical adsorption.This agrees with the flotation results.展开更多
Co-intensification was researched to accelerate gold leaching with regards to its electrochemical nature by using anodic intensifiers of heavy metal ions (Pb2+,Bi3+,Tl+,Hg2+ and Ag+) on the basis of hydrogen peroxide ...Co-intensification was researched to accelerate gold leaching with regards to its electrochemical nature by using anodic intensifiers of heavy metal ions (Pb2+,Bi3+,Tl+,Hg2+ and Ag+) on the basis of hydrogen peroxide assistant leaching on three different types of materials which were classified as a refractory sulphide gold concentrate,an easily leachable sulphide gold concentrate,and a low grade oxide gold ore according to their leaching characteristics.The results showed that,favorable co-intensification effects on the three materials were obtained and leaching time of gold was effectively shortened to no longer than 12 h from 16 to 24 h for hydrogen peroxide assistant leaching.For the five tested heavy metal ions,Bi3+and Tl+ presented co-intensifying effect on all the three materials,and Hg2+ caused co-intensifying effect on both refractory and easily leachable sulphide gold concentrates,and Pb2+ and Ag+ only had co-intensifying effect on the easily leachable sulphide gold concentrate.展开更多
Mercury-resistant strain D2 was isolated from mercury-contaminated soil and investigations on its 16S rDNA sequence,growth,minimal inhibitory concentrations(MICs) of metals,antibiotic susceptibility and mer gene were ...Mercury-resistant strain D2 was isolated from mercury-contaminated soil and investigations on its 16S rDNA sequence,growth,minimal inhibitory concentrations(MICs) of metals,antibiotic susceptibility and mer gene were conducted.The strain D2 can grow in the medium containing 60 mg/L mercury ion.It presents more than 99% identity of 16S rRNA gene with Pseudomonas aeruginosa,and exhibits high MIC values for heavy metals and a large spectrum antibiotics resistance.The mer RT gene sequence was amplified from chromosome.Strain D2 is identified as Pseudomonas aeruginosa and the resistance to mercuric ion is related to chromosome.展开更多
In this study,direct reduction-magnetic separation process was applied to enrich phosphorus and iron to prepare Fe-P crude alloy from a high phosphorus oolitic hematite ore(HPOH).The results show that at lower tempera...In this study,direct reduction-magnetic separation process was applied to enrich phosphorus and iron to prepare Fe-P crude alloy from a high phosphorus oolitic hematite ore(HPOH).The results show that at lower temperatures and with absence of any of additives,Fe cannot be effectively recovered because of the oolitic structure is not destroyed.In contrast,under the conditions of 15%Na_(2)SO_(4)and reducing at 1050℃ for 120 min with a total C/Fe ratio(molar ratio)of 8.5,a final Fe-P alloy containing 92.40%Fe and 1.09%P can be obtained at an overall iron recovery of 95.43%and phosphorus recovery of 68.98%,respectively.This metallized Fe-P powder can be applied as the burden for production of weathering resistant steels.The developed process can provide an alternative for effective and green utilization of high phosphorus iron ore.展开更多
Chalcopyrite dissolution was evaluated by bioleaching and electrochemical experiments with thermophile A. manzaensis（Acidianus manzaensis） and mesophile L. ferriphilum（Leptospirillum ferriphium） cultures at 65 ℃ ...Chalcopyrite dissolution was evaluated by bioleaching and electrochemical experiments with thermophile A. manzaensis（Acidianus manzaensis） and mesophile L. ferriphilum（Leptospirillum ferriphium） cultures at 65 ℃ and 40 ℃, respectively. It was investigated that the bioleaching of chalcopyrite was stepwise. It was reduced to Cu2 S at a lower redox potential locating in the whole bioleaching process by A. manzaensis at high temperature while only at initial days of bioleaching by L. ferriphilum at a relative low temperature. No reduced product was detected when the redox potential was beyond a high level（e.g., 550 m V（vs SCE）） bioleached by L. ferriphilum. Chalcopyrite bioleaching efficiency was substantially improved bioleached by A. manaensis compared to that by L. ferriphilum, which was mainly attributed to the reduction reaction occurring during bioleaching. The reductive intermediate Cu2 S was more amenable to oxidation than chalcopyrite, causing enhanced copper extraction.展开更多
In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was fo...In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate(TEOS)on the surface of the Fe particles.The samples were characterized by XRD,TEM,SAED,TG-DSC and VSM.The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si-O-Fe bond.The coated shell of silica can effectively protect the Fe cores from being oxidized.展开更多
In order to eliminate the effect of calcite associated with scheelite on the scheelite flotation, hydrochloric acid was used to dissolve the calcite, and the soaking solution was used to prepare CaSO_4 whiskers by hyd...In order to eliminate the effect of calcite associated with scheelite on the scheelite flotation, hydrochloric acid was used to dissolve the calcite, and the soaking solution was used to prepare CaSO_4 whiskers by hydrothermal reaction with sulfuric acid at ambient pressure. First, the condition experiments of preparing CaSO_4 whiskers by using CaCl_2 and H_2SO_4 were carried out to optimize reaction parameters of the crystallization process. The optimal conditions were: at 102 ℃ reaction temperature, 0,5 mol/L reactant concentration and 60 min reaction time. Then based on the condition experiments and considering keeping acid concentration stable for achieving HCl recycling, Calcium sulfate whiskers with the average diameter of 1.41 μm and the average aspect ratio of 109 were prepared by the soaking solution after evaporating to half of its volume and 1.0 mol/L H_2SO_4 at 102 ℃ for 60 min: After ion exchange processing,the filtrate could be used as HCl in the process of HCl dissolution.展开更多
Bioleaching and electrochemical experiments were conducted to evaluate pyrrhotite dissolution in the presence of pure L.ferriphilum and mixed culture of L. ferriphilum and A. caldus. The results indicate that the pyrr...Bioleaching and electrochemical experiments were conducted to evaluate pyrrhotite dissolution in the presence of pure L.ferriphilum and mixed culture of L. ferriphilum and A. caldus. The results indicate that the pyrrhotite oxidation behavior is the preferential dissolution of iron accompanied with the massive formation of sulfur in the presence of L. ferriphilum, which significantly hinders the leaching efficiency. Comparatively, the leaching rate of pyrrhotite distinctly increases by 68% in the mixed culture of L. ferriphilum and A. caldus at the 3rd day. But, the accumulated ferric ions and high p H value produced by bioleaching process can give rise to the rapid formation of jarosite, which is the primary passivation film blocking continuous iron extraction during bioleaching by the mixed culture. The addition of A. caldus during leaching by L. ferriphilum can accelerate the oxidation rate of pyrrhotite, but not change the electrochemical oxidation mechanisms of pyrrhotite. XRD and SEM/EDS analyses as well as electrochemical study confirm the above conclusions.展开更多
The efficient recovery of fluorite is paid more and more attention with the increasing application especially in strategic emerging industries.In this study,acrylic acid-2-acrylamido-2-methylpropane sulfonic acid copo...The efficient recovery of fluorite is paid more and more attention with the increasing application especially in strategic emerging industries.In this study,acrylic acid-2-acrylamido-2-methylpropane sulfonic acid copolymer(AAAMPS)was first used as the depressant in fluorite flotation,and its effect on the flotation separation of fluorite and dolomite in sodium oleate(NaOL)system was investigated.The depression mechanism was analyzed by contact angle measurement,zeta potential test,FTIR and XPS analyses.The micro-flotation test results showed that dolomite can be inhibited in fluorite flotation system in the addition of 2 mg/L AA-AMPS and 20 mg/L NaOL at pH 10.The CaF_(2) grade increased from 49.85%in the artificial mixed mineral to 89.60%in the fluorite concentrate.The depression mechanism indicated that AA-AMPS could adsorb strongly on dolomite surface by the chelation with Ca and Mg active sites.Moreover,the further adsorption of NaOL on dolomite surface was prevented by the AA-AMPS adsorption,but that on fluorite surface was little affected,thereby increasing the difference in the hydrophobicity and floatability of the two minerals.展开更多
Environmentally friendly flotation reagent,polyaspartic acid(PAPA),was tested as a potential selective depressant in the flotation separation of chalcopyrite and Cu-activated sphalerite.The depression mechanism of PAP...Environmentally friendly flotation reagent,polyaspartic acid(PAPA),was tested as a potential selective depressant in the flotation separation of chalcopyrite and Cu-activated sphalerite.The depression mechanism of PAPA was revealed by contact angle measurements,Zeta potential measurements,Fourier transform infrared spectroscopy(FT-IR)analysis and inductively coupled plasma(ICP)measurement.The micro-flotation tests with single minerals showed that PAPA selectively depressed Cu-activated sphalerite,while chalcopyrite remained floatable.Moreover,a concentrate containing 31.40%Cu with a recovery of 92.43%was obtained in flotation tests of artificially mixed minerals.Results of contact angle measurements,Zeta potential measurements and FT-IR spectrum revealed that PAPA exerted a much stronger adsorption on Cu-activated sphalerite surface than on chalcopyrite surface,preventing the further adsorption of sodium diethyl dithiocarbamate(DDTC)on its surface.ICP measurements indicated that PAPA had an excellent complexing ability with Cu^(2+)in flotation pulp,weakening the activation of Cu species on sphalerite surface and producing selective depression.展开更多
基金Projects(2022YFC2904504-4,2019YFC0408300)supported by the National Key R&D Program of ChinaProject(HB202302)supported by the Open Foundation of State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,China+1 种基金Project(51634009)supported by the National Natural Science Foundation of ChinaProject(B14034)supported by the National“111”Project,China。
文摘Stemming from the high costs and environmental pollution associated with the use of sodium sulfide in the separation and extraction processes of molybdenum bismuth ore,calcium hypochlorite was introduced as a substitute to facilitate the cleaner production of low-grade molybdenum bismuth ore in this study.The effects of calcium hypochlorite on molybdenite,bismuthinite,and pyrite were investigated through micro-flotation,flotation kinetics,batch flotation,Fourier transform infrared(FTIR)spectra,scanning electron microscopy energy dispersion spectra(SEM-EDS),and inductively coupled plasma-optical emission spectra(ICP-OES).The flotation tests results showed that calcium hypochlorite could selectively depress bismuthinite and pyrite.In comparison to sodium sulfide,calcium hypochlorite not only improved the flotation indicators for molybdenum and bismuth concentrates but also reduced the dosage of flotation reagents.Moreover,the chemical oxygen demand(COD)of tailings wastewater significantly decreased when using calcium hypochlorite as a depressant.Mechanism research revealed that the use of calcium hypochlorite as a depressant led to BiOCl precipitation on bismuthinite,which hindered the attachment of the collector.In summary,calcium hypochlorite serves as a more efficient and environmentally friendly depressant compared to sodium sulfide in the industrial production processes of low-grade molybdenum bismuth ore.
基金financially supported by the National Natural Science Foundation of China (No.51634009)the Institutions of Higher Learning Discipline Innovation Conference Program (111 Project) (No.B14034)the Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources Innovation Driven Plan of Central South University (No.2015CX005)
文摘The similar floatabilities of calcium minerals and the huge difference between scheelite and wolframite have resulted in difficulties during their separation by flotation in Shizhuyuan Mine. In this study, novel collectors, lead complexes of benzohydroxamic acid（Pb-BHA）,were introduced to modify the surface properties of scheelite and wolframite, thereby effectively and selectively improving floatability. The Pb-BHA complexes are found to be selective for the separation of scheelite and calcium minerals with little use of depressants and enable the synchronous flotation of scheelite and wolframite.Hence, a novel flotation process was developed for the recovery of tungsten minerals. The process is simplified greatly, and the recovery is improved by almost 10%.Removing or decreasing the amount of water glass contributes to the improvement of tungsten and fluorite recovery and the circulation of water and reagents, which benefits the environment.
基金supported by the Public Welfare Project of the National Scientific Research Institution (No.CAFRIFEEP201101),Chinathe National Biological Specimens and Resources Sharing Platform in Nature Reserve (No.2005DKA21404)
文摘Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest,deciduous broadleaved forest,coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition,elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16 S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites,and Subdivision 6 has the highest number of detectable operational taxonomic units（OTUs）. A significant single peak distribution pattern（P 〈 0.05） between the OTU number and the elevation was observed. The Jaccard and Bray–Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased（P 〈 0.01） with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship（P 〈 0.01） with different soil enzymes. Therefore,soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH,soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure.
基金financially supported by the National Natural Science Foundation of China (No. 51620105013)Dongying Fangyuan Nonferrous Metals Co., Ltd.
文摘In the newly developed oxygen-enriched bottom-blowing copper smelting process(also known as the SKS copper smelting process), Cu loss in slag is one of the most concerning issues. This paper presents our research results concerning the relationship between the Cu content of the matte and slag in the SKS process; the results are based on actual industrial production in the Dongying Fangyuan copper smelter. The results show that the matte grade strongly influences Cu losses in slag. The dissolved and entrained losses account for 10%–20% and 80%–90% of the total SKS industrial Cu losses in slag, respectively. With increasing matte grade, the dissolved and entrained Cu losses in the SKS slag both increase continuously. When the matte grade is greater than 68%, the content of Cu in the smelting slag increases much more dramatically. To obtain a high direct recovery of copper, the matte grade should be less than 75% in industrial SKS copper production.
基金the National Natural Science Foundation of China(Nos.51974364,51904339,52074355)the 13th Five-Year National Key R&D Program of China(No.2020YFC1909203)。
文摘Lime(CaO)and sodium humate(NaHA)were used as the combined depressant for arsenopyrite pre-treated by CuSO_(4) and butyl xanthate.Micro-flotation tests show that the combined depressant CaO and NaHA achieved the selective depression of arsenopyrite.Closed-circuit lab-scale test results indicate that the synergistic effect of CaO+NaHA achieved a satisfactory flotation separation of sphalerite and arsenopyrite,for which the Zn grade and recovery of Zn concentrate were 51.21%and 92.21%,respectively.Contact angle measurements,adsorption amount measurements and X-ray photoelectron spectroscopy analysis indicate that the dissolved calcium species(mainly as Ca(2+))were adsorbed on the mineral surfaces,thereby promoting NaHA adsorption.Moreover,the surface of the arsenopyrite absorbed more amount of calcium species and NaHA than that of the sphalerite,thereby accounting for the strong hydrophilic surface of arsenopyrite.The adsorption of NaHA on arsenopyrite was mainly chemical adsorption through its carboxyl groups and Ca atoms,whereas that on sphalerite surface was relatively weak.
基金Project(2016RS2016) supported by Provincial Science and Technology Leader Program,Hunan,ChinaProject(2017zzts807) supported by Postgraduate Innovative Research Projects of Central South University,China
文摘The composition of a collector directly affects its collecting performance in mineral flotation.In this study,three vegetable oils were used as the collectors,the flotation performance of scheelite and the differential analysis were studied through flotation experiments,zeta potential,contact angle measurement and Fourier transform infrared spectrum(FTIR)analysis.Flotation results show that the recovery of scheelite increases in the order of oleic acid<rapeseed oil<rice bran oil<soybean oil,especially in the pH range of 5-8.The distinction in the scheelite recovery is due to the different compositions of these collectors.The addition of LA,LNA and PA(<5%)can increase the recovery of scheelite with OA,but the addition of SA deteriorates the scheelite flotation.Results of zeta potential,contact angle measurement and FTIR analysis indicate that the collector adsorption on scheelite surface is enhanced when using the three vegetable oils.For the raw ore with 0.086%WO3,a rough concentrate containing 1.423%WO3 with the recovery of 84.22%is obtained using soybean oil as the collector.
基金Project(52012BAB07B0)supported by National "Twelfth Five-Year" Plan for Science&Technology Support,ChinaProject(2013zzts066)supported by the Graduate Student Self-innovation Program from Central South University,China
文摘Flotation experiments were performed to investigate the separation of muscovite and quartz in the presence of dodecylamine(DDA), tallow amine(TTA) and dodecyltrimethylammonium bromide(DTAC). The adsorption mechanisms of these three kinds of amines on muscovite and quartz were studied by FT-IR spectrum analysis, contact angle measurement and molecular dynamics(MD) simulation. The results reveal that the separation of muscovite from quartz is feasible at strong acid pulp condition using amine collectors. TTA and DTAC show poorer collecting ability for flotation of the two minerals compared with DDA. Physical adsorption is found to be the main adsorption module of amine collectors on muscovite and quartz by FT-IR analysis. MD simulation results show a strong physical adsorption ability of DDA+ cation on muscovite and quartz(muscovite(001):-117.31 kJ/mol, quartz(100):-89.43 kJ/mol), while neutral DDA molecular can hardly absorb onto the surface of these two minerals. These findings provide a novel explanation for the flotation mechanism from the perspective of MD simulation.
基金Project(51704058)supported by the National Natural Science Foundation of China
文摘The influence of pulp temperature on the floatability and adsorption behavior of fine wolframite with sodium oleate was investigated by microflotation experiments, electric conductivity tests, adsorption measurements, and FT-IR analysis. Microflotation results show that fine wolframite with sodium oleate exhibits a good floatability at pH 8–9. Electric conductivity tests indicate that the high temperature enhances the ionization degree and electric mobility of oleate species, then the flotation recovery of fine wolframite and the adsorption amount of sodium oleate are observed to increase with the rise in pulp temperature. The results of adsorption experiments are found to meet Freundlich isotherms successfully, and the isosteric enthalpy （ΔH^Θ） is in conformity with the chemical bonding. The changes in FT-IR analysis provide sufficient evidence that sodium oleate interacts with the metal cations of wolframite surface, and the increase in pulp temperature clearly promotes the chemisorption intensity. These findings will be beneficial to strengthen the flotation behavior of fine wolframite.
基金Project(2014CB643402) supported by the National Basic Research Program of ChinaProject(CX2013B082) supported by the Hunan Provincial Innovation Foundation for Postgraduate,China
文摘Flotation behavior and adsorption mechanism of octyl hydroxamic acid(OHA)on wolframite were investigated through flotation experiments,adsorption tests,zeta-potential measurements,infrared spectroscopy and solution chemistry calculations.Results of flotation and adsorption experiments show that the maximum values of flotation recovery and adsorption capacity occur around p H 9.In term of the solution chemistry calculations,the concentration of metal hydroxamate is greater than that of metal tungstate and metal hydroxyl,and metal hydroxamate compounds are identified to be the main species on wolframite surface at p H region of 8-10,contributing to the increase of OHA adsorption and flotation performance.Results of zeta-potential and IR spectra demonstrate that OHA adsorbs onto wolframite surface by chemisorptions.Hydroxamate ions can bond with Mn_2+/Fe_2+cations of wolframite surface,forming metal hydroxamate compounds,which is a key factor in inducing the hydrophobicity of wolframite under the conditions of maximum flotation.
基金The authors wish to express thanks to NationalNatural Science Foundation of China(No.5147416l)Innovation-driven Project of Guangxi Zhuang Autonomous Region(Nos.AA18242003 and AA148242003)。
文摘A new process for manufacturing organically compounded bentonite was devcloped successfully based on the organic intercalation andlayered structure of bentonitc.The main steps in the proposed process included wet sodium activation of bentonite ore,organic com-pounding and high-pressure roll grinding.The optimum procedure is recommended as follows:5 mass%of sodium carbonate powderand 30 wt.%water are added to activate the bentonite ore for 24 h to prepare activated bentonice;0.5 wt.%of organic molecules are adiedinto the activated bentonite for organic compounding for 12 h:then,the high-pressure rollgrinding is followed to treat the organicallycompounded bentonice;:and finally,drying and fine prinding are performed for prenaring the final organically compounded bentoniteprodiuct with 10 wt.%moisture and 98% passing 0.074 mm.The obtained organically compounded bentonite was characterized usingan X-ray diffractometer,a scanning electron microscope and anX-ray photoelectron spectrometer.To confirm the effect of organicallycompounded bentonite on green balls,the pelletizing tests were carried out.The rexsults showed that high-pressure roll grinding can notonly enhance the ability of the crystal layer to hold the combined water.but also strengthen the intercalation compounding of the organicadditive,which is beneficial for the formation of a fiber-interlaced structure of the organically compounded bentonite and improvesthe quality index of the bentonite itself.Also,the organically compounded bentonite is helpiul to improve the indexes of green balls.
基金support from the Key Projects in the National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period(No.2006BAB02A06).
文摘The minerals jamesonite and marmatite have similar surface properties.Separating them using a flotation method is inefficient.For separation of lead and zinc the lead mineral is generally floated preferentially to the zinc mineral,which appears in the sinks.In this study a new of collector,2-aminothiophenol,is introduced that can float a zinc mineral,as a product entrapped in foam,preferentially.Single mineral flotation tests revealed that 2-aminothiophenol has good selectivity for flotation of marmatite. An artificial mixture of minerals used in a flotation test showed that 2-aminothiophenol can effectively separate marmatite from jamesonite.A product assaying at 45.06%Zn and 4.06%Pb was produced.FTIR spectra were employed to probe the adsorption mechanism of 2-aminothiophenol onto marmatite.The results indicate that adsorption of 2-aminothiophenol onto jamesonite and marmatite were,respectively,physical adsorption and chemical adsorption.This agrees with the flotation results.
基金Project(50725416) supported by the National Natural Science Foundation for Distinguished Young Scholars of China
文摘Co-intensification was researched to accelerate gold leaching with regards to its electrochemical nature by using anodic intensifiers of heavy metal ions (Pb2+,Bi3+,Tl+,Hg2+ and Ag+) on the basis of hydrogen peroxide assistant leaching on three different types of materials which were classified as a refractory sulphide gold concentrate,an easily leachable sulphide gold concentrate,and a low grade oxide gold ore according to their leaching characteristics.The results showed that,favorable co-intensification effects on the three materials were obtained and leaching time of gold was effectively shortened to no longer than 12 h from 16 to 24 h for hydrogen peroxide assistant leaching.For the five tested heavy metal ions,Bi3+and Tl+ presented co-intensifying effect on all the three materials,and Hg2+ caused co-intensifying effect on both refractory and easily leachable sulphide gold concentrates,and Pb2+ and Ag+ only had co-intensifying effect on the easily leachable sulphide gold concentrate.
基金Project(50621063) supported by the National Natural Science Foundation of ChinaProject(2004CB619204) supported by the National Basic Research Program of ChinaProject(2009sk3035) supported by the Science and Technology Program of Hunan Province,China
文摘Mercury-resistant strain D2 was isolated from mercury-contaminated soil and investigations on its 16S rDNA sequence,growth,minimal inhibitory concentrations(MICs) of metals,antibiotic susceptibility and mer gene were conducted.The strain D2 can grow in the medium containing 60 mg/L mercury ion.It presents more than 99% identity of 16S rRNA gene with Pseudomonas aeruginosa,and exhibits high MIC values for heavy metals and a large spectrum antibiotics resistance.The mer RT gene sequence was amplified from chromosome.Strain D2 is identified as Pseudomonas aeruginosa and the resistance to mercuric ion is related to chromosome.
基金Projects(AA18242003,AA148242003)supported by Innovation-driven Project of Guangxi Zhuang Autonomous Region,ChinaProject(51474161)supported by the National Natural Science Foundation of China。
文摘In this study,direct reduction-magnetic separation process was applied to enrich phosphorus and iron to prepare Fe-P crude alloy from a high phosphorus oolitic hematite ore(HPOH).The results show that at lower temperatures and with absence of any of additives,Fe cannot be effectively recovered because of the oolitic structure is not destroyed.In contrast,under the conditions of 15%Na_(2)SO_(4)and reducing at 1050℃ for 120 min with a total C/Fe ratio(molar ratio)of 8.5,a final Fe-P alloy containing 92.40%Fe and 1.09%P can be obtained at an overall iron recovery of 95.43%and phosphorus recovery of 68.98%,respectively.This metallized Fe-P powder can be applied as the burden for production of weathering resistant steels.The developed process can provide an alternative for effective and green utilization of high phosphorus iron ore.
基金Project(2010CB630903)supported by National Basic Research Program of ChinaProject(51374249)supported by the National Natural Science Foundation of China
文摘Chalcopyrite dissolution was evaluated by bioleaching and electrochemical experiments with thermophile A. manzaensis（Acidianus manzaensis） and mesophile L. ferriphilum（Leptospirillum ferriphium） cultures at 65 ℃ and 40 ℃, respectively. It was investigated that the bioleaching of chalcopyrite was stepwise. It was reduced to Cu2 S at a lower redox potential locating in the whole bioleaching process by A. manzaensis at high temperature while only at initial days of bioleaching by L. ferriphilum at a relative low temperature. No reduced product was detected when the redox potential was beyond a high level（e.g., 550 m V（vs SCE）） bioleached by L. ferriphilum. Chalcopyrite bioleaching efficiency was substantially improved bioleached by A. manaensis compared to that by L. ferriphilum, which was mainly attributed to the reduction reaction occurring during bioleaching. The reductive intermediate Cu2 S was more amenable to oxidation than chalcopyrite, causing enhanced copper extraction.
文摘In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate(TEOS)on the surface of the Fe particles.The samples were characterized by XRD,TEM,SAED,TG-DSC and VSM.The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si-O-Fe bond.The coated shell of silica can effectively protect the Fe cores from being oxidized.
基金provided by the National Key Technology R&D Programs from the Ministry of Science and Technology of China(No.2012BAB07B05)the Program of Introducing Talents of Discipline to Universities(Supported by the 111 Project,B14034)the Fundamental Research Funds for the Central Universities of Central South University(No.2016zzts104)
文摘In order to eliminate the effect of calcite associated with scheelite on the scheelite flotation, hydrochloric acid was used to dissolve the calcite, and the soaking solution was used to prepare CaSO_4 whiskers by hydrothermal reaction with sulfuric acid at ambient pressure. First, the condition experiments of preparing CaSO_4 whiskers by using CaCl_2 and H_2SO_4 were carried out to optimize reaction parameters of the crystallization process. The optimal conditions were: at 102 ℃ reaction temperature, 0,5 mol/L reactant concentration and 60 min reaction time. Then based on the condition experiments and considering keeping acid concentration stable for achieving HCl recycling, Calcium sulfate whiskers with the average diameter of 1.41 μm and the average aspect ratio of 109 were prepared by the soaking solution after evaporating to half of its volume and 1.0 mol/L H_2SO_4 at 102 ℃ for 60 min: After ion exchange processing,the filtrate could be used as HCl in the process of HCl dissolution.
基金Project(2010CB630903) supported by the National Basic Research Program of ChinaProject(51374249) supported by the National Natural Science Foundation of China
文摘Bioleaching and electrochemical experiments were conducted to evaluate pyrrhotite dissolution in the presence of pure L.ferriphilum and mixed culture of L. ferriphilum and A. caldus. The results indicate that the pyrrhotite oxidation behavior is the preferential dissolution of iron accompanied with the massive formation of sulfur in the presence of L. ferriphilum, which significantly hinders the leaching efficiency. Comparatively, the leaching rate of pyrrhotite distinctly increases by 68% in the mixed culture of L. ferriphilum and A. caldus at the 3rd day. But, the accumulated ferric ions and high p H value produced by bioleaching process can give rise to the rapid formation of jarosite, which is the primary passivation film blocking continuous iron extraction during bioleaching by the mixed culture. The addition of A. caldus during leaching by L. ferriphilum can accelerate the oxidation rate of pyrrhotite, but not change the electrochemical oxidation mechanisms of pyrrhotite. XRD and SEM/EDS analyses as well as electrochemical study confirm the above conclusions.
基金Project(52004333)supported by the National Science Foundation of ChinaProject(2021CB1002)supported by Hunan International Joint Research Center for Efficient and Clean Utilization of Critical Metal Mineral Resources,China。
文摘The efficient recovery of fluorite is paid more and more attention with the increasing application especially in strategic emerging industries.In this study,acrylic acid-2-acrylamido-2-methylpropane sulfonic acid copolymer(AAAMPS)was first used as the depressant in fluorite flotation,and its effect on the flotation separation of fluorite and dolomite in sodium oleate(NaOL)system was investigated.The depression mechanism was analyzed by contact angle measurement,zeta potential test,FTIR and XPS analyses.The micro-flotation test results showed that dolomite can be inhibited in fluorite flotation system in the addition of 2 mg/L AA-AMPS and 20 mg/L NaOL at pH 10.The CaF_(2) grade increased from 49.85%in the artificial mixed mineral to 89.60%in the fluorite concentrate.The depression mechanism indicated that AA-AMPS could adsorb strongly on dolomite surface by the chelation with Ca and Mg active sites.Moreover,the further adsorption of NaOL on dolomite surface was prevented by the AA-AMPS adsorption,but that on fluorite surface was little affected,thereby increasing the difference in the hydrophobicity and floatability of the two minerals.
基金financial supports from the National Natural Science Foundation of China(Nos.51974364,51904339)Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral,China(No.2018TP1002)。
文摘Environmentally friendly flotation reagent,polyaspartic acid(PAPA),was tested as a potential selective depressant in the flotation separation of chalcopyrite and Cu-activated sphalerite.The depression mechanism of PAPA was revealed by contact angle measurements,Zeta potential measurements,Fourier transform infrared spectroscopy(FT-IR)analysis and inductively coupled plasma(ICP)measurement.The micro-flotation tests with single minerals showed that PAPA selectively depressed Cu-activated sphalerite,while chalcopyrite remained floatable.Moreover,a concentrate containing 31.40%Cu with a recovery of 92.43%was obtained in flotation tests of artificially mixed minerals.Results of contact angle measurements,Zeta potential measurements and FT-IR spectrum revealed that PAPA exerted a much stronger adsorption on Cu-activated sphalerite surface than on chalcopyrite surface,preventing the further adsorption of sodium diethyl dithiocarbamate(DDTC)on its surface.ICP measurements indicated that PAPA had an excellent complexing ability with Cu^(2+)in flotation pulp,weakening the activation of Cu species on sphalerite surface and producing selective depression.
