A novel molybdenite depressant for efficient selective flotation separation of chalcopyrite and molybdenite

A novel small molecule depressant(M-DEP)was used to separate chalcopyrite and molybdenite via flotation.The results showed that M-DEP had an excellent selective depression on molybdenite,while had little effect on the flotation of chalcopyrite.The adsorption capacity of M-DEP on the surface of molybdenite was greater than that on chalcopyrite surface.The adsorption of M-DEP reduced the floatability of molybdenite and had less effect on the floatability of chalcopyrite,which was due to its different adsorption modes on the surface of the two minerals.Furthermore,the interaction between chalcopyrite and M-DEP was mainly chemical interaction,and almost all of the adsorbed M-DEP molecules were removed and replaced by sodium butyl xanthate(SBX).By contrast,hydrophobic interaction was the main way in which M-DEP was adsorbed on the molybdenite surface with little chemical interaction,which was less interfered by SBX addition.Therefore,M-DEP had a super selective depression on molybdenite.The study provided a novel depressant and approach for the deep separation of chalcopyrite and molybdenite via flotation.

Using pectin to separate talc and molybdenite through the surface modification with Cu^(2+):Applications and mechanism

Organic depressants have low selectivity in separating molybdenite and talc because their metal sites lack activity for organics chemisorption.In this study,surface modification by copper sulfate was used to induce the differential adsorption of pectin onto molybdenite and talc surfaces for enhanced flotation separation.Contact-angle experiments,scanning electron microscopy,adsorption measurements,timeof-flight secondary-ion mass spectrometry,and X-ray photoelectron spectroscopy analyses were conducted to reveal the interaction mechanism.Results illustrated that molybdenite and talc could not be separated using pectin alone,while molybdenite was selectively depressed after surface modification by copper sulfate and this effect was strengthened under alkaline conditions.Metal sites(Mg,Si and Mo)of talc and molybdenite themselves were unable to react with pectin,whereas Cu+would deposit and further function as active site for pectin chemisorption after surface modification.However,the quantity of deposited Cu sites dropped on talc surface and increased on molybdenite surface with increased pH,and the Mo atoms of molybdenite crystal were activated to take part in pectin chemisorption.Therefore,more pectin was adhered on molybdenite surface,which imparted molybdenite stronger wettability.Herein,surface-modification through metal ions can enable the differential adsorption of organic depressants and enhance the flotation separation of minerals.

Oxidation roasting of molybdenite concentrate

In order to investigate the oxidation roasting of molybdenite concentrate in pure oxygen atmosphere, experiments at 673, 723, 773, 873 and 973 K were carried out. The phase transitions and morphology evolutions of the samples obtained at different temperatures after reacting for different time were analyzed by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results showed that molybdenite concentrate was oxidized directly to Mo O3 in pure oxygen atmosphere. There were remarkable changes of the morphologies of products with the increase of the roasting temperature. It was also found that sintering phenomenon occurred during the roasting process in pure oxygen when the temperature was above 873 K. The composition of sintered sample was mainly comprised of Mo O3 and some unreacted Mo S2.

Re–Os dating of molybdenite and in-situ Pb isotopes of sulfides from the Lamo Zn–Cu deposit in the Dachang tin-polymetallic ore field, Guangxi, China

The Dachang tin-polymetallic district, Guangxi,China, is one of the largest tin ore fields in the world. Both cassiterite-sulfide and Zn–Cu skarn mineralization are hosted in the Mid-Upper Devonian carbonate-rich sediments adjacent to the underlying Cretaceous Longxianggai granite(91–97 Ma). The Lamo Zn–Cu deposit is a typical skarn deposit in the district and occurs at the contact zone between the Upper Devonian limestone and the granite.The ore minerals mainly consist of sphalerite, arsenopyrite,pyrrhotite, galena, chalcopyrite, and minor molybdenite.However, the age of mineralization and source of the metals are not well constrained. In this study, we use the molybdenite Re–Os dating method and in-situ Pb isotopes of sulfides from the Lamo deposit for the first time in order to directly determine the age of mineralization and the tracing source of metals. Six molybdenite samples yielded a more accurate Re–Os isochron age of 90.0 ± 1.1 Ma(MSWD = 0.72), which is much younger than the reported garnet Sm–Nd isochron age of 95 ± 11 Ma and quartz fluid inclusions Rb–Sr isochron age of 99 ± 6 Ma. This age is also interpreted as the age of Zn–Cu skarn mineralization in the Dachang district. Further, in this study we found that in-situ Pb isotopes of sulfides from the Lamo deposit and feldspars in the district's biotite granite and granitic porphyry dikes have a narrow range and an overlap of Pb isotopic compositions(^(206) Pb/^(204) Pb =18.417–18.594,^(207) Pb/^(204) Pb = 15.641–15.746, and^(208) Pb/^(204) Pb = 38.791–39.073), suggesting that the metals were mainly sourced from Cretaceous granitic magma.

LA-ICP-MS Zircon U-Pb Dating of Intermediate-Acidic Intrusive Rocks and Molybdenite Re-Os Dating from the Bangpu Mo (Cu) Deposit, Tibet and its Geological Implication

The multi-stage intrusions of intermediate-acid magma occur in the Bangpu mining district, the petrogenic ages of which have been identified. The times and sequences of their emplacement have been collated and stipulated in detail in this paper by using the laser ablation-inductively coupled plasma-mass spectrometry （LA-ICP-MS） zircon U-Pb dating method. The ages of biotite monzogranite that were formed before mineralization in the southwest of this mining district are 70±1 Ma （mean square of weighted deviates （MSWD） =9.5, n=8） and 60.60±0.31 Ma （MSWD=3.8, n=16）, which belong to the late Cretaceous-early Paleocene in age. That means, they are products of an early tectonicmagmatic event of the collision between the Indian and Asian continentals. The ages of ore-bearing monzogranite porphyry and ore-bearing diorite porphyrite are 16.23±0.19 Ma （MSWD=2.0, n=26） and 15.16±0.09 Ma （MSWD=3.9, n=5） separately, which belong to the middle Miocene in age; namely, they are products of the Gangdese post-collision extensional stage when crust-mantle materials melted and mixed as well as magmatic intrusion simultaneously occurred. Some zircons with ages of 203.6±2.2 Ma （MSWD=1.18, n=7） were captured in the ore-bearing diorite porphyrite, which shows that there had been tectono-magmatic events in the late Triassic-early Jurassic. Molybdenum （copper） ore-bodies produced in the monzogranite porphyry and copper （molybdenum） ore-bodies produced in the diorite porphyrite are the main ore types in this ore deposit. The model ages of Re-Os isotopic dating for the 11 molybdenite are 13.97-15.84 Ma, while isochron ages are 14.09±0.49 Ma （MSWD=26）. The isochron ages of seven molybdenite from molybdenum （copper） ore with monzogranite porphyry type are 14.11±0.31 Ma （MSWD=5.2）. There is great error in the isochron ages of four molybdenite from copper （molybdenum） ore with diorite porphyrite type, and their weighted average model ages of 14.6±1.2 Ma （MSWD=41）, which generally represent the mineralization age. The results about the Re-Os isotopic dating of molybdenite in the ore of different types have limited exactly that, the minerlazation age of this ore deposits is about 14.09 Ma, which belongs to the middle Miocene mineralization. The Bangpu deposit has a uniform metallogenic dynamics background with the porphyry type and skarn-type deposits such as Jiama, Qulong and others.

Molybdenite-limestone oxidizing roasting followed by calcine leaching with ammonium carbonate solution

Oxidizing roasting of molybdenite with lime can significantly reduce SO2pollution compared with the traditional roastingwithout lime.However,the calcine is subsequently leached by sulfuric acid,resulting in serious equipment corrosion and abundantnon-recyclable CaSO4slag.In this work,a novel process,in which the molybdenite was roasted with CaCO3followed by(NH4)2CO3solution leaching,was proposed to improve the art of lime roasting-sulfuric acid leaching.Oxidizing roasting of molybdenite withCaCO3was investigated through thermodynamic calculation,thermogravimetric analysis and roasting experiments.The results showthat the products of the oxidizing reaction of MoS2in the presence of CaCO3and O2are CaSO4,CaMoO4and CO2at573-1000K.The MoS2conversion rate achieves approximately99%and the sulfur-retained rate attains approximately95%with aCaCO3-to-MoS2molar ratio of3.6at500°C for1h by adding5%mineralizer A(mass fraction).The leaching results show that theleaching rate of Mo reaches98.2%at85°C for7h with a(NH4)2CO3concentration of600g/L and a liquid-solid ratio of10mL/g.The results presented are potential to develop a novel cleaner technique for ammonium molybdate production.

LA-ICP-MS Zircon U-Pb Geochronology of the Fine-grained Granite and Molybdenite Re-Os Dating in the Wurinitu Molybdenum Deposit,Inner Mongolia,China

The Wurinitu molybdenum deposit,located in Honggor,Sonid Left Banner of Inner Mongolia,China,is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite.The wall rocks are composed of Variscan porphyritic-like biotite granite and the Lower Ordovician Wubin'aobao Formation.LA-ICP-MS zircon U-Pb dating of the fine-grained granite reveals two stages of zircons,one were formed at 181.7±7.4 Ma and the other at 133.6±3.3 Ma.The latter age is believed to be the formation age of the fine-grained granite,while the former may reflect the age of inherited zircons,based on the morphological study of the zircon and regional geological setting.The Re-Os model age of molybdenite is 142.2±2.5 Ma,which is older than the diagenetic age of the fine-grained granite.Therefore the authors believe that the metallogenic age of the Wurinitu molybdenum deposit should be nearly 133.6±3.3 Ma or slightly later,i.e.,Early Cretaceous.Combined with regional geological background research,it is speculated that the molybdenum deposits were formed at the late Yanshanian orogenic cycle in the Hingganling-Mongolian orogenic belt,belonging to the relaxation epoch posterior to the compression and was associated with the closure of the Mongolia-Okhotsk Sea.

Mechanism study on flotation separation of molybdenite from chalcocite using thioglycollic acid as depressant

Effects of collectors(butyl xanthate(BX), O-isopropyl-N-sulfur ethyl carbamate(Z-200) and emulsified kerosene), dereagent(sodium sulfide) and depressant thioglycollic acid(TGA) on the flotation of chalcocite and molybdenite were investigated through flotation. The first principle theory was adopted to understand the difference of their surfaces and reaction between minerals and reagents. Results of flotation tests revealed that selectivity of emulsified kerosene is the best of three collectors in separation of chalcocite and molybdenite, though the others also display excellent collecting properties. Sodium sulfide can effectively remove collectors adsorbed on chalcocite surface, and TGA is an effective depressant of chalcocite at pH 8-9. Through first principle study, molybdenite displays relatively stronger covalence property while bonding interaction between copper atoms in chalcocite enhanced its ionicity. Bonding interaction is weaker in reaction of TGA and molybdenite, so it shows higher hydrophobicity and better flotability. Therefore, TGA is an effective inhibitor in the separation.

Re-Os Dating of Molybdenite from the Yaogangxian Tungsten Deposit,South China,and Its Geological Significance

The Yaogangxian tungsten deposit is located in the central part of the Nanling polymetailic metallogenic province. The orebodies occur as veins. Wolframite and molybdenite are the dominant ore minerals. Two samples were selected for molybdenite Re-Os dating in order to elucidate the timing of mineralization. Re-Os datings of molybdenite from quartz-woiframite veins and disseminated in granite yield ages of 153±7 Ma and 163.2±4.2 Ma respectively. The results indicate that the Yaogangxian tungsten deposit is the product of large-scale metallogenesis in the middle Yanshanian period in South China, and that the evolution from late magmatic to postmagmatic hypothermal mineralization occurred at about 10 Ma. The rhenium content of molybdenite in the Yaogangxian tungsten deposit suggests that the ore materials originated from the crust.

Flotation separation of molybdenite and talc using tragacanth gum as depressant and potassium butyl xanthate as collector

Tragacanth gum(TG)was explored as a depressant to realize the flotation separation of molybdenite and talc.The flotation experiments indicated that when using potassium butyl xanthate(PBX)as a collector,molybdenite showed excellent floatability while talc was completely depressed by TG,thus realizing the flotation separation of the two minerals.X-ray photoelectron spectroscopy(XPS)analysis results showed that TG was adsorbed on molybdenite surface via chemisorption.The results of contact angle measurement,Fourier transform infrared(FTIR)spectroscopy,and time-of-flight secondary ion mass spectrometry(ToF-SIMS)indicated that the pre-adsorption of TG on molybdenite could not hinder the further chemisorption of PBX on molybdenite.Because PBX has no collecting ability on talc,the flotation separation of molybdenite and talc came true using PBX to collect molybdenite and TG to depress talc.

Timing of carbonatite-hosted U-polymetallic mineralization in the supergiant Huayangchuan deposit,Qinling Orogen:Constraints from titanite U-Pb and molybdenite Re-Os dating

The newly-discovered supergiant Huayangchuan uranium(U)-polymetallic(Sr,Se,REEs,Ba,Nb and Pb)deposit is located in the Qinling Orogen,central China.The deposit underwent multistage mineralization,with the main carbonatite ore stage being the most important for the U,Nb,REE,Sr and Ba endowments.According to the mineral assemblages,the main carbonatite ore stage can be divided into three substages,i.e.,sulfate(Ba-Sr),alkali-rich U and REE-U mineralization.Main-stage titanite from the Huayangchuan igneous carbonatite are rich in high field strength elements(HFSEs,e.g.,Zr,Nb and REEs),and show clear elemental substitutions(e.g.,Ti vs.Nb+Fe+Al and Ca+Ti vs.Fe+Al+REE).High-precision LA-ICP-MS titanite dating yielded a U-Pb age of 209.0±2.9 Ma,which represents the mainstage mineralization age at Huayangchuan,and is coeval with the local carbonatite dyke intrusion.This mineralization age is further constrained by the Re-Os dating of molybdenite from the Huayangchuan carbonatite,which yielded a weighted mean age of 196.8±2.4 Ma.Molybdenite Re contents(337.55-392.75 ppm)and C-OSr-Nd-Pb isotopic evidence of the Huayangchuan carbonatite both suggest a mantle origin for the carbonatite.Our study supports that the Late Triassic carbonatite magmatism was responsible for the world-class U-Mo-REE mineralization in the Qinling Orogen,and that the regional magmatism and ore formation was likely caused by the closure of the Mianlue ocean and the subsequent North China-South China continent-continent collision.

Molybdenite alkali fusion and leaching:reactions and mechanism

The production of MoO3 from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied.The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere.Then the fused products were leached in water and the dissolved molybdenum was recovered as ammonium molybdate.The ammonium molybdate was then calcined to produce mo-lybdic oxide.At the fusion stage,the effect of the mass ratio of carbonate to sulfide on the reaction products and the solubility of the products was investigated.The results show that during the fusion,sodium molybdate and sodium sulfate are the final reaction products and sodium sulfide is detected as an intermediate reaction product.By melting at 850℃with 5wt%excess carbonate,the maximum solubility of the products is obtained.The molybdenum is recovered from the solutions as ammonium molybdate.

A Study of the Rhenium-Osmium Geochronometry of Molybdenites

This study deals with the first application of the isotope dilution - inductively coupled plasma mass spectrometry in the rhenium-osmium geochronometry in China. The chemical separation procedure included decomposition of samples by means of alkali fusion, extraction of rhenium by acetone and extraction of osmium by distillation. The recovery of both elements in the entire process was more than 90% . The blanks of analyses were 0.07 ng for rhenium and 0.01 ng for 187Os. The mineralization ages of molybdenites from four molybdenum deposits in China were determined by using this method, with a precision (2σ)of about ±3% . These results agree satisfactorily with their geological backgrounds. The Re-Os method can directly determine ages of metal deposits and reflect the true ages more reliably than other dating methods that only determine the ages of country rocks from which mineralization ages are inferred. As many hydrothermal sulphide deposits usually contain molybdenites, this method has bright prospects of wide application.

Kinetics of oxidation roasting of molybdenite with different particle sizes

The kinetics of oxidation roasting of molybdenum concentrate was studied by differential thermal−gravimetric experiments and non-isothermal analysis methods.The results show that high temperature is beneficial for oxidation of molybdenum concentrate.The initial oxidation temperature of the molybdenum concentrate is 450℃,and the rapid oxidation occurs above 500℃.The oxidation process conforms to the unreacted shrinking nucleus model.The early stage of the oxidation is controlled by chemical reaction with the apparent activation energy of 123.180 kJ/mol,while the later stage is controlled by internal diffusion with the apparent activation energy of 80.175 kJ/mol.Moreover,the oxidation rate is closely related to particle size of the concentrate.The smaller the particle size is,the larger the oxidation rate is.

SHRIMP Zircon U-Pb and Molybdenite Re-Os Datings of the Superlarge Donggou Porphyry Molybdenum Deposit in the East Qinling,China,and Its Geological Implications

Located in the eastern part of the East Qinling molybdenum belt, the Donggou deposit is a superlarge porphyry molybdenum deposit discovered in recent years. The authors performed highly precise dating of the mineralized porphyry and ores in the Donggou molybdenum deposit. A SHRIMP U-Pb zircon dating of the Donggou aluminous A-type granite-porphyry gave a rock-forming age of 112±1 Ma, and the ICP-MS Re-Os analyses of molybdenite from the molybdenum deposit yielded ReOs model ages ranging from 116.5±1.7 to 115.5±1.7 Ma for the deposit. The ages obtained by the two methods are quite close, suggesting that the rocks and ores formed approximately at the same time. The Donggou molybdenum deposit formed at least 20 Ma later than the Jinduicheng, Nannihu, Shangfanggou and Leimengou porphyry molybdenum deposits in the same molybdenum belt, implying that these deposits were formed in different tectonic settings.

Study of the interfacial interactions in the molybdenite floatation system

Interfacial interactions involving Van der Waals force, hydrophobic attractive force and hydration exclusive force were investigated in this paper. The interfacial interactive free energy of a series of interfaces occurring between minerals, water, collectors and bubble was calculated. The results show that a Van der Waals attractive force and a hydrophobic attractive force exist between each mineral and water interface. The hydrophobic attractive force between molybdenite and water is markedly weaker than the hydrophobic attractive force between gangue and water. The hydrophobic attractive force between collector molecules and water is the main driving force that causes the collectors to become dispersed in the pulp. The strong hydrophobic attractive force between molybdenite and the bubble interface is the basic reason for the natural floatability of molybdenite. The Van der Waals force between molybdenite and the collectors is attractive in water solution, but it is not the cause of the main force between them. The main force that results in the collection effect is a hydrophobic attractive force caused by the Lewis acid-base interaction at the molybdenite surface. A floatation experiment shows that the adsorption intensity of the collector on the molybdenite surface is not the crucial factor for molybdenite floatation. Rather, the dispersing capability of the collector in the water phase and its selectivity for the various minerals in the floatation system are more important.

Features and mechanisms of self-sintering of molybdenite during oxidative roasting

Roasting experiments were carried out with pure reagents as raw materials.The self-sintering behaviors of molybdenite(MoS_(2))during oxidation were investigated by thermodynamic calculation,XRD,SEM-EDS and high-temperature in situ analysis.The results indicate that the desulfurization efficiency of MoS_(2) pellet decreases with the increase of roasting temperature from 600 to 700℃,owing to the expansion of sintered area.At the very beginning of roasting,sintered layer can be rapidly formed and cover the pellet surface on the windward side,and meanwhile,MoO_(2)and Mo_(4)O_(11) intensively appear and constitute the sintered layer together with MoO_(3).Moreover,it is proven that MoO_(3)-rich products containing low-valence molybdenum oxides have low melting points,thus easy to be melted during the occurrence of exothermic reaction between MoS_(2) and O_(2),which leads to the sintering of materials.

Bio-dissolution of Cu,Mo and Re from molybdenite concentrate using mix mesophilic microorganism in shake flask

The application of the response surface methodology and the central composite design（CCD） technique for modeling and optimization of the influence of some operating variables on copper,molybdenum and rhenium recoveries in a bioleaching process was investigated.Three main bioleaching parameters,namely pH,solid concentration and inoculum percent,were changed during the bioleaching tests based on CCD.The ranges of the bioleaching process variables used in the design were as follows：pH1.46-2.14,solid concentration 0.95%-11.05%,and inoculum percent 1.59%-18.41%.A total of 20 bioleaching tests were carried out by the CCD method according to software-based designed matrix.Empirical model equations were developed according to the copper,molybdenum and rhenium recoveries obtained with these three parameters.Model equations of responses at the base of parameters were achieved by using statistical software.The model equations were then individually optimized by using quadratic programming to maximize copper,molybdenum and rhenium recoveries individually within the experimental range.The optimum conditions for copper recovery were pH 1.68,solid concentration 0.95% and the inoculum 18.41%（v/v）,while molybdenum and rhenium recoveries were 2.18% and 24.41%,respectively.The predicted values for copper,molybdenum and rhenium recoveries were found to be in good agreement with the experimental values.Also jarosite formation during bioleaching tests was also investigated.

U-Pb Zircon and Re-Os Molybdenite Geochronology of the W-Mo Mineralized Region of South Qinling, China, and their Tectonic Implications

A W-Mo mineralized region is located along the northern margin of the South Qinling tectonic belt of China. WMo mineralization occurs mainly in Cambrian–Ordovician clastic and carbonate rocks, and the ore bodies are structurally controlled by NW–SE-and NNE–SSW-striking faults. Evidence for magmatism in the area is widespread and is dominated by intermediate–felsic intrusives or apophyses, such as the Dongjiangkou, Yanzhiba, Lanbandeng, and Sihaiping granitic bodies. Quartz-vein-type mineralization and fault-controlled skarn-type mineralization dominate the ore systems, with additional enrichment in residual deposits. At present, there are few or insufficient studies on(1) the age of mineralization,(2) the relationship between intermediate–felsic granite and W-Mo mineralization,(3) the source of ore-forming materials, and(4) the metallogenic and tectonic setting of the mineralized area. In this paper, we present geochronology results for numerous intrusive granitic bodies in the South Qinling tectonic belt. U-Pb zircon geochronology of the Lanbandeng monzogranite and Wangjiaping biotite monzogranite yields ages of 222.7 ± 2.3 and 201.9 ± 1.8 Ma, respectively. In contrast to the Late Triassic age of the Lanbandeng monzogranite, the age of the newly discovered Wangjiaping biotite monzogranite places it at the Triassic–Jurassic boundary. Re-Os molybdenite geochronology on the Qipangou W-Mo deposit yielded a model age of 199.7 ± 3.9 Ma, indicating the deposit formed in the early Yanshanian period of the Early Jurassic. Granitoid intrusions in the mineralized area are characterized by composite granite bodies that crystallized at ca. 240–190 Ma. While there were multiple stages of intrusion, most occurred at 210–220 Ma, with waning magmatic activity at 200–190 Ma. The Re-Os age of molybdenite in the region is ca. 200–190 Ma, which may represent a newly discovered period of W-Mo metallogenesis that occurred during the final stages of magmatism. The heat associated with this magmatism drove ore formation and might have provided additional ore-forming components for metallogenesis(represented by the Wangjiaping biotite monzogranite). Ore materials in the mineralized area were derived from mixed crustal and mantle sources. Enrichment of the region occurred during intracontinental orogenesis in the late Indosinian–Yanshanian, subsequent to the main Indosinian collision. At this time, the tectonic environment was dominated by extension and strike-slip motion.

Flotation of Xinhua molybdenite using sodium sulfide as modifier

The feasibility of using sodium sulfide as the sole modifier for the flotation of Xinhua molybdenite ore was examined.The potential mechanisms involved in the different flotation systems were discussed.The comparative flotation results reveal that in the kerosene-sodium silicate flotation system,better recovery and grade of the molybdenum are obtained using sodium sulfide as the slurry pH adjustment agent than using CaO.Under the optimal conditions(64 g/t kerosene and 6 kg/t Na2S),satisfied recovery and grade of molybdenite concentrate can be achieved(84%and 8.2%,respectively),indicating that sodium sulfide is a potential substitute modifier of sodium silicate.The open-circuit flotation test results further confirm the effectiveness of sodium sulfide which may render recycling the tailing water possible and make the flotation process more environmental acceptable and more economical due to the less use of kerosene and scavengers.