Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation

The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challenge.Through various techniques,such as mi-croflotation tests,Fourier transform infrared spectroscopy,scanning electron microscopy(SEM)observation,X-ray photoelectron spec-troscopy(XPS),and Raman spectroscopy measurements,this study explored the use of ferric ions(Fe^(3+))as a selective depressant for ga-lena.The results of flotation tests revealed the impressive selective inhibition capabilities of Fe^(3+)when used alone.Surface analysis showed that Fe^(3+)significantly reduced the adsorption of isopropyl ethyl thionocarbamate(IPETC)on the galena surface while having a minimal impact on chalcopyrite.Further analysis using SEM,XPS,and Raman spectra revealed that Fe^(3+)can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface,effectively depressing IPETC adsorption and increasing surface hydrophilicity.These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.

Separation of galena and chalcopyrite using the difference in their surface acid corrosion characteristics

Galena(PbS)and chalcopyrite(CuFeS_(2))are sulfide minerals that exhibit good floatability characteristics.Thus,efficiently separating them via common flotation is challenging.Herein,a new method of surface sulfuric acid corrosion in conjunction with flotation separation was proposed,and the efficient separation of galena and chalcopyrite was successfully realized.Contact angle test results showed a substantial decrease in surface contact angle and a selective inhibition of surface floatability for corroded galena.Meanwhile,the contact angle and floatability of corroded chalcopyrite remained almost unaffected.Scanning electron microscope results confirmed that sulfuric acid corrosion led to the formation of a dense oxide layer on the galena surface,whereas the chalcopyrite surface remained unaltered.X-ray photoelectron spectroscopy results showed that the chemical state of S^(2-)on the surface of corroded galena was oxidized to SO_(4)^(2-).A layer of hydrophilic PbSO4was formed on the surface,leading to a sharp decrease in galena floatability.Meanwhile,new hydrophobic CuS_(2),CuS,and Cu_(1-x)Fe_(1-y)S_(2-z)species exhibiting good floatability were generated on the chalcopyrite surface.Finally,theoretical analysis results were further verified by corrosion–flotation separation experiments.The galena–chalcopyrite mixture was completely separated via flotation separation under appropriate corrosion acidity,corrosion temperature,and corrosion time.A novel approach has been outlined in this study,providing potential applications in the efficient separation of refractory copper–lead sulfide ore.

Flotation behaviors of chalcopyrite and galena using ferrate(Ⅵ) as a depressant

This paper investigated the effects of potassium ferrate(PF)on the flotation performances of chalcopyrite and galena.The flotation results showed that PF obviously depressed galena,but had little effects on the floatability of chalcopyrite within pH range of 4.0–12.0.Zeta potential tests showed that the addition of PF induced the formation of more amounts of hydrophilic species on the surface of galena under an alkaline environment.Industrial grade O-isopropyl-N-ethyl thionocarbamate(IPETC)chemically adsorbed on the surface of the PF-treated chalcopyrite and galena after its addition.Contact angle measurements showed that with the addition of PF,the contact angle of the galena surface significantly decreased compared with the chalcopyrite surface.Localized electrochemical impedance spectroscopy(LEIS)tests showed that the addition of PF increased the impedance of the galena surface.X-ray photoelectron spectroscopy(XPS)analyses revealed that the formation of hydrophilic species,namely lead sulfite,lead hydroxide and ferric hydroxide,on the galena surface,decreased its floatability in the presence of PF,while the formation of hydrophobic species,namely copper disulfide and elemental sulfur,on the chalcopyrite surface,maintained its floatability.Finally,a descriptive model for the reaction of PF with chalcopyrite and galena was proposed.

Theoretical study of 2-mercaptobenzimidazole derivatives as chelating collectors in flotation separation of galena and pyrite

Three 2-mercaptobenzimidazole derivatives,1-ethyl-2-mercapto-benzimidazole(EMBI),1-propyl-2-mercapto-benzimidazole(PMBI)and 1-benze-2-mercapto-benzimidazole(BMBI),were designed and synthesized in the paper,and their collecting behavior in flotation separation process of galena over pyrite was investigated by flotation tests on lab scale.Apart from this,density functional theory(DFT)calculation and molecular dynamics(MD)simulation were also used to elucidate their collecting mechanism.Results of flotation tests indicate that separation of galena over pyrite is feasible at pH 10,and BMBI has the best floatability among three collectors.DFT calculations show that BMBI has the highest occupied molecular orbital(HOMO)energy and strongest collecting effciency.The adsorption mode of three collectors on mineral surface by MD method indicates that the combination processes of collectors with mineral are exothermic,and the higher the binding energy,the frmer the collector adsorbs on the mineral surface and the higher collecting capacity.The calculation results demonstrate that the floatability of three collectors follows the order:BMBI>PMBI>EMBI,which is highly consistent with the flotation tests.

Seaweed glue as a novel polymer depressant for the selective separation of chalcopyrite and galena

The use of seaweed glue(SEG)as a novel polymer depressant for the separation of chalcopyrite from galena with butyl xanthate(BX)as a collector was studied through microflotation experiments.Contact angle,adsorption,dynamic potential,and infrared spectral analyses were conducted to clarify the mechanism underlying the action of SEG on minerals.The results of microflotation experiments indicated that chalcopyrite could be selectively separated from galena by using a SEG depressant concentration of 15 mg·L^-1,BX concentration of 10 mg·L^-1,and methyl isobutyl carbinol concentration of 8.5 mg·L^-1 at pH 8.0.A Cu concentrate with a grading of 23.68wt% was obtained at a recovery rate of 81.52% from mixed minerals with 8.29wt% Cu content.Contact angle analysis showed that the effect of SEG on the wettability of galena was stronger than that on the wettability of chalcopyrite.Adsorption,zeta potential,and FT-IR spectral analyses revealed that SEG and BX were coadsorbed on the surfaces of galena.SEG depressed galena by covering xanthate ions in the functional groups of-COO and mainly underwent weak physisorption on chalcopyrite.These mechanisms account for the ability of SEG to depress galena effectively while enabling chalcopyrite flotation.

Comparative analysis of the dissolution kinetics of galena in binary solutions of HCl/FeCl_3 and HCl/H_2O_2

A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken.The dissolution kinetics of the galena was found to depend on leachant concentration,reaction temperature,stirring speed,solid-to-liquid ratio,and particle diameter.The dissolution rate of galena ore increases with the increase of leachant concentration,reaction temperature,and stirring speed,while it decreases with the increase of solid-to-liquid ratio and particle diameter.The activation energy （Ea） of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl3 /8.06 M HCl,and it suggests the surface diffusion model for the leaching reaction,while the Ea value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H2O2 /8.06 M HCl,which suggests the surface chemical reaction model for the leaching reaction.Furthermore,the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two cases.Finally,the rate of reaction based on the reaction-controlled process has been described by a semiempirical mathematical model.The Arrhenius and reaction constants of 11.023 s^-1,1.25×10^-4 and 3.65×10^2 s^-1,8.02×10^ 6 were calculated for the 0.3 M FeCl3/8.06 M HCl and 8.06 M H2O2/8.06 M HCl binary solutions,respectively.

Selective depression mechanism of ferric chromium lignin sulfonate for chalcopyrite–galena flotation separation

Selective recovery of chalcopyrite–galena ore by flotation remains a challenging issue.The development of highly efficient,low-cost,and environmentally friendly depressants for this flotation is necessary because most of available reagents(e.g.,K_2Cr_2O_4)are expensive and adversely affect the environment.In this study,ferric chromium lignin sulfonate(FCLS),which is a waste-product from the paper and pulp industry,was introduced as a selective depressant for galena with butyl xanthate(BX)as a collector.Results show that the residue recovery of Pb in Cu concentrate was substantially reduced to 4.73%using FCLS compared with 10.71%using the common depressant K_2Cr_2O_4.The underlying mechanisms were revealed using zeta-potential measurements and X-ray photoelectron spectroscopy(XPS).Zeta-potential measurements revealed that FCLS was more efficiently absorbed onto galena than onto chalcopyrite.XPS measurements further suggested that FCLS enhanced the surface oxidation of galena but prevented that of chalcopyrite.Thus,FCLS could be a potential candidate as a depressant for chalcopyrite–galena flotation because of its low cost and its lack of detrimental effects on the environment.

Thermodynamics and density functional theory study of potassium dichromate interaction with galena

The adsorption heat and reaction rate constant of potassium dichromate on the surface of galena were studied. The results indicate that potassium dichromate tends to adsorption on the galena surface. The reaction order is only 0.08385, suggesting that the concentration of potassium dichromate has little influence on its adsorption on the galena surface. In addition, the simulation of CrO2 4- adsorption on the PbS （100） surface in the absence and presence of O2 was carried out by density functional theory （DFT）. The calculated results show that CrO2 4- species adsorb energetically at the Pb-S bond site, and the presence of O2 can enhance this adsorption.

Kinetics of the electrochemical process of galena electrodes in the diethyldithiocarbamate solution

The electrochemical process of galena in a pH 12.8 buffer solution was investigated using chronoamperometry and chronopotentiometry. To establish kinetic parameters on the surface of galena in the diethyldithiocarbamate solution, the exchange current density and the dependence of current density on reaction time were determined. Experimental results demonstrate that the exchange current density of galena is 1.585× 10^-2A/m2 in the diethyldithiocarbamate-free solution. In the diethyldithiocarbamate solution, the thickness of lead diethyldi- thiocarbamate adsorbed on the surface of galena is 3.28 molecular layers, the diffusion coefficient of diethyldithiocarbamate on the surface of galena electrodes is 1.13 × 10^-10 m2/s, and the exchange current density of galena is 0.45 A/m2. Lead diethyldithiocarbamate on the surface of galena is firmly adsorbed.

Depression behaviors of N-thiourea-maleamic acid and its adsorption mechanism on galena in Mo-Pb flotation separation

In present study,a novel organic depressant N-thiourea-maleamic acid(TMA)was synthesized and applied as a galena depressant in the flotation separation of Mo-Pb ores.The depression behaviors of TMA were tested through flotation experiments.A wider separation window for single minerals over 90.0%was obtained at 30.0 mg/L TMA,confirming that TMA could depress galena significantly,while effected molybdenite floatability slightly.An effective separation was obtained for artificially mixed minerals and actual Mo-Pb ores.The adsorption mechanism on galena was revealed by UV-Vis spectra,zeta potential tests,Fourier transform infrared spectroscopy(FT-IR)analysis,contact angle tests and X-ray photoelectron spectroscopy(XPS)analysis.The zeta potentials of galena became more negative and the contact angle of galena dropped from initial 74.36°to 57.8°with 30.0 mg/L TMA depressant,inferring that TMA had adsorbed on galena surface.The analysis results of UV-Vis spectra,FT-IR and XPS gave further evidence that TMA might chemisorb on galena surface via Pb sites on galena surface and the thiourea group in TMA molecular structure,while the carboxyl group played a role of hydrophilicity.

OXIDATION OF GALENA IN AMMONIUM CARBONATE SOLUTION AND APPLIED REACTOR

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Characterization of Galena and Vein Paragenesis in the Penjom Gold Mine,Malaysia:Trace Elements,Lead Isotope Study and Relationship to Gold Mineralization Episodes

The Penjom Gold Mine is located 30 km from the Bentong-Raub Suture at the western boundary of the Central Belt in Peninsular Malaysia. Gold mineralization hosted within the vein system is associated with pyrite, arsenopyrite, and minor base metals including galena. Trace element and lead isotope analysis was undertaken on nine samples that represent two stages of galena formed during two tectonic events. Both the Pb isotopes and the trace elements show that the first stage galena within the mineralized areas at the footwall has different geochemical characteristics compared with galena in non mineralized areas in the hanging wall, suggesting that galena crystallized from two different ore fluids and probably at two different times. Higher Te, Se and Bi in the galena from the mineralized area may indicate hydrothermal fluids that migrate through the structural conduit and leached out the metal along the pathway that consist of dominant carbonaceous unit. The Pb isotopic ratio composition are transitional between the bulk crustal growth and an upper crustal growth curve, indicating that derivation was from arc rocks associated with continental crust or a crustal source that includes arc volcanic and old continental sedimentary rocks.

Studies of Grinding Media Corrosion from Galvanic Interaction on Galena Flotation

This study has been done to determine the galvanic interaction between five types of grinding media (mild steel, cast iron, 10% chromium, 20% chromium, and ceramic media) and galena, in situ of the mill. The ceramic media has a significantly not galvanic interaction with galena and high chromium media has a significantly weaker galvanic interaction with galena, and produces a very much lower amount of oxidize iron species in the mill discharge than mild steel medium. The investigation of the various reactions occurring on the galena surface was investigated by ethylene diamine-tetra acetic acid disodium salt (EDTA) extraction and X-ray photoelectron spectroscopy (XPS) measurements. The floatability of galena is dependent on the galvanic current between grinding media and galena during grinding because the current is relative to the amount of iron oxidation species and the reduction rate on galena. Iron oxidation species depressed galena flotation. The optimum galena flotation was achieved by selecting grinding conditions that enabled iron oxidation to be controlled.

An Experimental Calibration on the Sphalerite-Galena Sulfur Isotope Geothermometer

A new experimental calibration was undertaken in this study to get a more reliable sphalerite-galena sulfur isotope geothermometer. The experimental conditions selected in study were very similar to those of natural hydrothermal solution. The high-precision SF6 method was used in sulfur isotope analyses. The obtained calibration curve for sulfur isotope fractionation between sphalerite and galena can be expressed with the equation 10001nαSp-Gn= 0.74×106T-2+0.08.

Influence of mechanical excitation on adsorption of sodium diethylamino dithio-formate on galena and sphalerite

The adsorption of SDD on galena, pyrite and sphalerite in the process of agitating and in the process of grinding using different mediums is studied by ultraviolet spectrophotometer. It has been found that the grinding process can cause more adsorption of SDD on these sulfides than the agitating process do and the environments of grinding with metal mediums do the best. The reason for these phenomena is because of the action of the mechanical activation and mechanical excitation. The ulteriorly principles of these theories are discussed in this paper.

DIRECT REDUCTION OF GALENA AT MODERATE TEMPERATURES

The direct reduction of galena with hydrogen at 873—973 K could be described by the shrink- ing core model in the chemically controlled region.The reaction was revealed to be of first or- der with respect to hydrogen concentration and the activation energy is 79.0 kJ/mol.Be- cause of the fairly large interface tension between the solid galena and the liquid Pb,the SEM second electron images showed that the liquid Pb film is difficult to be formed on the unreacted galena surface in reaction process.

Kinetics of electrochemical process of galena electrode in diethyldithiocarbamate solution

The electrode process of galena in diethyldithiocarbamate (DDTC) solution at pH 11.4 has been investigated using cyclic voltammetry, potentiostatic and chronopotentiometry. Electrodeposit of PbD 2 on galena electrode surface can occur while the electrode potential is higher than -0.05?V. The relationship between the current density caused by diffusion and reaction time has been ascertained, and the diffusion coefficient of DDTC on galena surface in DDTC solution is about 1.12×10 -6 cm 2/s. A passive PbD 2 film covers the surface of galena electrode.

Hydrometallurgical Processing of a Nigerian Galena Ore in Nitric Acid: Characterization and Dissolution Kinetics

The physico-chemical characterization and dissolution kinetics study of a Nigerian galena ore in nitric acid has been undertaken. The effects of acid concentration, temperature, particle size, stirring speed and solid/liquid ratio on the leaching of galena were investigated. The X-ray fluorescence data showed that the galena ore used in the study exists mainly as PbS. Lead (Pb) was detected as the major metal for galena with metals such as Na, Ca, Fe, Zn, Al and Mg occurring as minor elements. The XRD analysis also confirmed the originality of the galena ore as it revealed that galena exists mainly as lead sulphide (PbS). The Fourier transform infrared (FTIR) analysis also supported the XRF and XRD analysis by revealing the presence of sulphur in the ore. The scanning electron micrograph (SEM) analysis revealed a high level of crystallinity of the ore. Results of the leaching studies showed that galena dissolution in nitric acid (HNO3) increases with increasing concentration of nitric acid, temperature and stirring rate, and decreases with increasing particle diameter and solid/liquid ratio. In 10 M HNO3 at a temperature of 90°C using 75 μm particle diameter with solid/liquid ratio of 20 g/L and stirring speed of 540 rpm, about 84.5% of galena was dissolved in 150 minutes. The values of activation energy, order of reaction and Arrhenius constant calculated at the conditions above for galena were 27.01 KJ/mol, 0.93, 26.71 s-1 respectively. The mechanism of dissolution of galena was established to follow the shrinking core model for the diffusion controlled mechanism, with surface chemical reaction as the rate controlling step for the leaching process. Finally, the XRD analysis of the post-leaching residue revealed the presence of gahnite and anglesite.

Modeling and Optimization of Galena Dissolution in Hydrochloric Acid: Comparison of Central Composite Design and Artificial Neural Network

Response surface methodology (RSM) and Artificial neural network (ANN) were used for the simulation and optimization of galena dissolution in hydrochloric acid. The galena ore was characterized for structure elucidation using FTIR, SEM and X-ray diffraction spectroscopic techniques and the results indicate that the galena ore exists mainly as lead sulphide (PbS). A feed-forward neural network model with Leverberg-Marquardt back propagating training algorithm was used to predict the response (lead yield). The leaching temperature, acid concentration, solid/liquid ratio, stirring rate and leaching time were defined as input variables, while the percentage yield of lead was labelled as output variable. The multilayer perceptron with architecture of 5-9-1 provided the best performance. All the process variables were found to have significant impact on the response with p-values of 2 of 0.991 and 1.00, respectively. A non-dominated optimal response of 85.25% yield of lead at 343.96 K leaching temperature, 3.11 M hydrochloric acid concentration, 0.021 g/ml solid/liquid ratio, 362.27 rpm stirring speed and 87.37 min leaching time was established as a viable route for reduced material and operating cost using RSM.

Electrochemical characteristics of couple electrode of galena-pyrite in different solutions

Cyclic voltammogram was used to study the electrochemical properties of the couple electrode of galena pyrite in xanthate and diethyldithiocarbamate (DDTC) solutions. When galena connects with pyrite, there exists galvanic interaction between two minerals. Because pyrite is nobler than galena, the anode oxidation of collector on the surface of galena is improved, and the anode oxidation of reagent on the surface of pyrite is weaken. The experimental results showed that it is difficult for the dixanthogen and (DDTC) 2 to be adsorbed on the surface of pyrite under galvanic interactions with galena.