Galena Particles Research Articles

Isotopic ratio analysis of individual sub-micron particles via spICP-TOFMS

Single particle ICP-TOFMS is used to measure isotope ratios within individual sub-micron particles. We explore the advantages and limitations of this method through the analysis of stable and radiogenic isotope pairs in monazite and galena particles.

Utilizing the high intensity conditioning process with a multi-bladed impeller to enhance the flotation of fine-grained galena

Due to the increasing demand for lead metal, the recovery of fine-grained galena resources is also constantly strengthening. High intensity conditioning (HIC) has been promoted as an efficient technology for enhancing the flotation of fine minerals. In this study, the effect of the HIC process with a multi-bladed impeller on the flotation of fine-grained galena was investigated at different agitation times and speeds. By analysis of flow field characteristics, adsorption experiments, and particle aggregation observation, the correlation mechanism of HIC affecting the flotation of fine-grained galena was revealed. Compared to the results without the HIC, the flotation recovery was 95.38% when the agitation speed was 2000 rpm and the agitation time was 5 min. Mechanistic studies showed that obtaining an appropriate slurry flow rate with external energy input not only benefited the dispersion of galena particles and reagents, but also enhanced their adsorption. The appropriate impeller shear stress can increase the flow rate difference of the slurry, making it easier for fine-grained galena to form clusters with appropriate particle size, compact structure, and small porosity, which promoted mineral flotation. This study will provide a basis for adjusting the floatability of fine sulfide mineral flotation from mixing operations.

Enhancement of shear flocculation of a galena suspension by ultrasonic treatment

The enhancement of shear flocculation of a galena suspension by ultrasound in the presence of sodium isopropyl xanthate and potassium ethyl xanthate was investigated by studying the effects of surfactant concentration on flocculation efficiency, contact angle, and zeta potential. Strong flocculation was obtained under alkaline conditions (pH > 9) and a high ultrasound power level (150 W). Although the ultrasonic treatment increased the negativity of the zeta potential of the galena particles, this did not decrease the flocculation efficiency, thereby showing that the hydrophobic interactions between the particle were stronger than the electrical double-layer repulsion resulting from xanthate adsorption. The findings indicate that the ultrasonic treatment promoted the adsorption of surfactants onto the mineral surfaces.

The Effect of Macroscopic Particle Features on Mineral Dissolution

Mineral dissolution is a dynamic process in which kinetics depend on the reactive surface area, orientation, and geometry of the dissolving mineral grain. Dissolution rate is, thus, not represented by a single value, but rather, by a spectrum that is affected by the reactivity of different types of surface features. Such dissolution rate spectra are usually obtained by very detailed studies of perfectly cleaved surfaces by atomic force microscopy or in situ studies, such as flow-through experiments. This study visualizes dissolution progress by repeated X-ray computed tomography scans of a single particle. This allows studying the influence of larger particle features, such as corners and edges, at the interception of macroscopic faces of particles, as well as the influence of those macroscopic features on the dissolution rate spectra. As a suitable case study, the dissolution of a monomineralic galena (PbS) particle in ethaline is studied. The observed changes in particle geometry are evaluated using a newly developed empirical model in order to break down the rate spectra as a function of the particle geometry. Results illustrate that dissolution rates are exponentially correlated with the distance to crystal corners and edges. The reactivity map generated from these exponential relations shows a linear trendline with the dissolution rates over the entire surface of the studied galena particle. The empirical reactivity map developed here opens the possibility of predicting the dissolution rate of particulate materials based on computed tomography and the optimal geometrical properties of the particles that maximize the dissolution, e.g., size and shape.

Analysis of the Behavior of As and Pb during the Pretreatments Applied to a Jarosite Residue for the Recovery of Gold and Silver

The recovery of valuable metals from jarosites is a topic of great relevance regarding the implementation of the circular economy; however, these materials also contain metals such as arsenic and lead, which are harmful to health and the environment. Considering these factors, it is important to monitor these metals at each stage of treatment used to recover the valuable metals. In the present work, the behavior of As and Pb was assessed during the pretreatment conducted on a jarositic residue using direct zinc leaching (DLR), as well as leaching in cyanide and cyanide media with glycine. It was found that when no DLR pretreatment was performed, As and Pb naturally dissolved in the cyanide-leaching medium at concentrations of 34.08 mg/L and 99.12 mg/L, respectively. When an alkaline treatment was conducted on the residue (DLR-AH), it was found that there was no presence of As and Pb in the cyanidation solution, while in the case of the cyanide solution with glycine, we observed 83.35 mg/L of As and 213.63 mg/L of Pb. During the oxidizing alkaline hydrothermal treatment (DLR-AHO), 27.5 mg/L of As and 106.78 mg/L of Pb were detected in the cyanide solution. In the cyanide solution with glycine, there was less dissolution of As and Pb (11.68 and 66.75 mg/L), respectively. Finally, when desulfurization of the DLR was conducted prior to the DLR-AHO treatment, the dissolution of As and Pb increased due to the elemental sulfur covering the arsenopyrite and galena particles, so that, when removed, these were more susceptible to pretreatment and cyanidation.

Dual Role of Fe2+ in the Galena Flotation and Influence on Selective Separation

Fe ions, as one of the unavoidable metal ions, are present in flotation pulp as ferric and ferrous species, and the effect of ferric species on the flotation behavior of sulfide minerals has been widely discussed in the above literatures. However, the effect of ferrous species has rarely been noticed. In this paper, the effect of ferrous species on the flotation behavior and surface characteristics of galena was investigated by using microflotation, zeta potential measurements, X-ray photoelectron spectrometer (XPS) analysis, and density functional theory (DFT) calculations. Microflotation tests indicated that the flotation recovery of galena with potassium butyl xanthate (KBX) as collector was significantly decreased with the addition of Fe2+ in the pulp, and the recovery was further decreased with increasing dosage of Fe2+. In addition, the finer the galena particles, the greater the decrease in flotation recovery. Zeta potential analysis illustrated that the isoelectric point (IEP) was shifted from 4.4 to 5.8 due to the adsorption of ferrous hydroxyl complexes on the galena surface and the zeta potential. XPS surface analysis suggested that the surface oxidation of galena was alleviated by the consumption of O2 in the pulp, which reduced the adsorption of the collector KBX on and the oxidation of xanthates to dixanthogens. Density functional theory (DFT) calculations confirmed that the ferrous hydroxyl complex FeOH+ could be adsorbed on the galena surface by interactions between Fe and S atoms.

Interactions between coarse and fine galena and quartz particles and their implications for flotation in NaCl solutions

In this study we have investigated the interactions between coarse and fine galena and quartz particles and their implications for flotation in NaCl solutions. Tested were four different particle systems: (CC) Coarse galena/Coarse quartz, (CF) Coarse galena/Fine quartz, (FC) Fine galena/Coarse quartz and (FF) Fine galena/Fine quartz. The flotation experiments were carried out on the four particle systems in NaCl concentrations of 10 mM and 100 mM, at pH 9. It was found that the recovery was the highest for the CC particle system, and the lowest for the FF particle system. The experiments also indicated that the recovery improved for the higher NaCl concentration.As part of this study, we calculated the total interaction free energy as a function of separation distance for each pairwise combination of particles and bubbles, for each test condition. It was found that for all particle systems, galena/quartz interactions are dominated by repulsion. The interactions between two galena particles indicated attraction as the dominating force, while the interactions between quartz particles showed repulsion in 10 mM NaCl, which changed to attraction with an increase in NaCl concentration. Galena/air bubble interactions were controlled by repulsive electrostatic interactions in 10 mM NaCl, but these interactions became attractive in 100 mM NaCl salt solutions. On the other hand, the quartz/air bubble interactions were always repulsive, irrespective of the NaCl concentration. Based on these theoretical predictions, we postulate that the stronger repulsion of quartz particles away from the air bubbles could be the driving force for galena recovery.

A theoretical and experimental study of the effects of NaCl and the competitive chemisorption of ions at the surface sites in the context of galena flotation

• The recovery of galena by collector-less flotation improves as a result of NaCl addition. • Our galena surface complexation model is a “two-site / not amphoteric” model. • The theoretical predictions of the models support the experimental results. • The decreasing repulsion at higher ionic strengths corresponds to a higher galena recovery. In this study we have investigated the effects of increasing the NaCl concentration on the flotation of galena. Experiments were carried out using a Hallimond tube in NaCl solutions with concentrations of 1, 10 and 100 mM, at pH 9. It was found that the recovery of galena by collector-less flotation improved for higher NaCl concentrations. Zeta potential measurements made on galena particles conditioned in NaCl solutions were used to calibrate the parameters for describing a chemisorption model representing charge regulation at the galena binding sites. Our galena chemisorption model presented here is a “two-site/not amphoteric” surface complexation model. A chemisorption model representing the charge regulation process on the surface of an air bubble has also been applied. The zeta potentials calculated using these models were in agreement with the measured values, indicating that these models can be applied to predict the potentials on the surface of galena and an air bubble for a range of NaCl concentrations and pH. To investigate the mechanisms of particle-bubble interactions for each NaCl concentration, the total interaction free energy as a function of the separation distance between galena and an air bubble was determined. It was found that at a NaCl concentration of 1 mM, due to adsorption of ions at the galena surface, repulsion dominated the interaction, and the lowest galena recovery was reported. With an increase in NaCl concentration in solution to 100 mM, the total interaction between galena and an air bubble was represented by a purely attractive total interaction free energy curve. The theoretical predictions of the models supported the experimental results, with a stronger attraction predicted by the models at higher ionic concentrations, corresponding to a higher galena recovery during flotation.

The significance of positive and negative inertial forces in Particle-Bubble interaction and their role in the general flotation kinetics model

In this study, a theoretical evaluation of the effect of inertial forces in particle-bubble interactions during the flotation process is presented and supported by the experimental data. The effects of positive and negative inertial forces were analyzed by comparing the differences between the models, which either consider or neglect the inertial forces. The Sutherland collision model and the Nguyen attachment model that completely ignore the effect of particle’s inertial forces (inertialess models) were implemented into the general flotation kinetic model. The modified model was then compared with one of the most accurate inertial models, which considers the Generalized Sutherland Equation (GSE) for collision efficiency along with the Dobby-Finch model for attachment efficiency. The flotation kinetics of chalcopyrite and galena particles were estimated using the general flotation kinetic model in order to demonstrate the effect of particle density on the model, which emphasizes the effect of inertial forces. The influence of positive and negative inertial forces on flotation kinetics was evaluated for various explicit parameters such as particle density, turbulence (energy dissipation), and bubble size and velocity. Obtained theoretical results clearly showed the potential of the particle density to counterbalance the negative effects of the inertial forces. The capability of the positive inertial forces for galena particles (high density) to overcome its negative effect was shown when the general flotation kinetic model was used. Theoretical calculations were further confirmed by experimental bubble loading measurements. It was shown that the inertial forces should not be omitted in any flotation model amidst concerns over the complexity.

Effect of Mechanical Activation on the High-Temperature Oxidation Behavior of Galena

The high-temperature (up to 1000°C) oxidation behavior of natural galena after mechanical activation has been studied by thermogravimetry, differential thermal analysis, mass spectrometry, and X-ray diffraction. The results demonstrate that the nature of the energy stored during mechanical activation of galena influences its reactivity. Mechanical activation has been shown to influence the morphology of galena particles, and we have compared oxidation processes during continuous heating in flowing air before and after mechanical activation.

The selective flotation separation of galena from sphalerite with a novel collector of 5-amyl-1, 2, 4-triazole-3-thione

In this paper, 5-amyl-1,2,4-triazole-3-thione (ATT) was firstly applied as a collector in flotation separation of galena (PbS) from sphalerite (ZnS). Micro-flotation results demonstrated that ATT selectively floated out galena from its mixture with sphalerite at pH ≤10.5. FTIR (Fourier transform infrared), adsorption capacity and contact angle indicated that to increase the pulp pH from ~6.2 to 10.0 dramatically reduced the adsorption of ATT on sphalerite, while had an insignificant effect on its adsorption towards galena. In situ AFM (atomic force microscopy) recommended a monolayer adsorption of ATT on galena surfaces at pH ~6.2 and 10.0. FTIR and XPS (X-ray photoelectron spectroscopy) gave out unequivocal evidences that ATT chemisorbed onto galena through combining surface Pb(II) with ATT's exo-S to generate PbS bond, which orientated ATT's amyl group outward for attaching bubbles, thus to realize the hydrophobization flotation of galena particles.

Effects of pyrite on the flotation behavior and electrochemical interaction of different particle sizes of galena in the presence of diethyldithiocarbamate

ABSTRACT Lead is widely used metals and pyrite is usually associated with galena. In addition, galena is prone to super-crushing during the grinding process. In this study, the galvanic interaction between different particle sizes of galena and pyrite were studied by electrochemistry, adsorption test and flotation test, respectively. Adsorption tests and microflotation tests indicated the recovery of galena of different sizes in mixed ore was decreased 5%–15% compared with single galena flotation results. The results of electrochemical measurement pointed out that the presence of pyrite enhances the corrosion rate of galena, and the finer the galena particles were, the stronger the electrochemical corrosion effect with pyrite became.

Continuous bio-hydrometallurgical extraction of zinc from a bulk lead-zinc flotation concentrate on a pilot scale

The high interlock between the fine particles of sphalerite and galena in some parts of the Goushfil mine (Isfahan, Iran) ore has significantly reduced the flotation efficiency. According to the acceptable capability of bioleaching in the recovery of metals from the complex mineralogical resources, the feasibility of zinc extraction from a low-grade (34% Zn) bulk flotation concentrate was investigated. The applied concentrate was processed using a large-scale continuous bioleaching system, including three 50 l stirred bioreactors in series. After 15 days, 83% of zinc was recovered by implementing a mixed culture of moderately thermophile bacteria at pH = 1.8 and 15% solid content. In the next stage, 83% of the accompanying iron impurity was removed from the leachate by jarosite precipitation. Then, about 99.9% of zinc was gained by solvent extraction using 25% saponified D2EHPA at pH = 3.5, O/A = 1 at two steps. Consequently, bioleaching, in combination with bulk flotation, can be successfully applied to recover zinc from the complex lead-zinc ore of the examined deposit.

The mechanism and kinetics of the transformation from marcasite to pyrite: in situ and ex situ experiments and geological implications

Despite the natural abundance of pyrite and marcasite and their intergrowth, and a wealth of information they can provide on the physical–chemical conditions of mineral deposits, a complete mechanistic and kinetic study on the phase transformation from the thermodynamically metastable polymorph marcasite to the stable polymorph pyrite is yet to be made. This limits the application of marcasite as an indicator mineral for low-temperature geological environments. Here, we report results from in situ synchrotron powder X-ray diffraction and ex situ anneal/quench experiments at 400–540 °C, demonstrating that the mechanism and kinetics of this transformation depend not only on temperature, but also on particle size, the presence of water vapor, and the presence of pyrite inclusions in marcasite. Under dry conditions, the transformation is limited by surface nucleation and occurs via epitaxial nucleation of pyrite on marcasite, with {100}pyrite//{101}marcasite and {001}pyrite//{010}marcasite. In contrast, in the presence of water vapor, there is little crystallographic orientation relationship between the two phases; the transformation is still limited by surface nucleation, but modification of the surface properties by water vapor results in a different nucleation mechanism, and consequently different kinetics. Kinetic analysis estimates a half-life of 1.5 Ma at 300 °C for the transformation under dry conditions with small and pyrite-free marcasite grains, but this estimation should be used with extreme caution due to the complexity of the transformation. From synchrotron X-ray fluorescence elemental mapping, trace elements (As and Pb) play an insignificant role in the transformation. However, the presence of a fluid phase changes the behavior of Pb. Under dry conditions randomly oriented particles of galena formed in pyrite, while under water vapor conditions arrays of nano- to microparticles of galena precipitated in pores. This study highlights that although the natural occurrence of marcasite can indicate low-temperature environments, precise estimation of temperature should not be made without considering the influences from various reaction parameters.

Difference in flotation behavior of galena by single and multi-step chronoamperometric oxidation

The relationship between electrochemical oxidation (Chronoamperometry) of galena surfaces and collocterless galena flotation was investigated in detail. The chronoamperometry (CA) micro flotation experiments and zeta potential experiments were performed with ground galena particles (106x53 mu m). In addition, contact angle measurements were carried out with a freshly cleaved galena sample at pH 4 in order to investigate any changes in galena surface hydrophobicity after the surface oxidation electrochemically. The results from this study indicated that there is a strong link between the nano/micro-physico-chemical properties of a sulphide on galena surfaces and collectorless flotation of galena particles at pH 4. The results were also supported with the electrokinetics behavior and contact angle values of galena particles.

Determination of Optimum Parameters for Flotation of Galena: Effect of Chain Length and Chain Structure of Xanthates on Flotation Recovery.

The structure of the xanthates’ hydrocarbon (C–H) chain is one of the major factors which affect flotation recovery. The effectiveness and the collecting power of xanthates increase with increasing chain length and vary depending on the chain structure: branched and straight chains. In this regard, the influences of length (2–5 carbon) and structure (straight: normal and branched: iso) of xanthate’s hydrocarbon chain on flotation recovery of galena were investigated under different experimental conditions: xanthate concentration, conditioning time, air flow rate (AFR), and air bubble size. Because of the steric effects of the chain structure, the branched chain xanthates gave lower flotation recoveries with shorter conditioning times compared to those with straight chain xanthates. Over-conditioning with straight chain xanthates resulted in hydrophobic aggregation of galena particles which resulted in the detachment of galena particles from air bubbles due to increasing weight, leading to lower flotation recoveries. In the case of flotation with different AFRs, the flotation recoveries increased with increasing AFR to 7 lph and further increase in AFR (10 lph) negatively affected the flotation recoveries when particles had insufficient hydrophobic surfaces. The maximum flotation recoveries were obtained with the addition of MIBC (methyl isobutyl carbinol) as a frother; the size of the air bubbles deceased with increasing MIBC concentration which increased higher encounter/collision probability of air bubbles with galena particles, resulting in higher flotation recoveries.

Influence of dextrin on beneficiation of components from copper flotation concentrate

Depressants are one of the most important reagents in flotation process. They are used to improve upgrading selectivity. Natural depressants, especially starch and its derivatives, are one of the most significant polysaccharides used in polymetallic sulphide ores flotation. In the paper influence of dextrin on flotation of copper, organic carbon and mineral components from rougher concentrate was investigated. It has been shown, that dextrin is a good depressant for organic carbon and clay minerals with micas as long as the appropriate collector for sulphides are added. Moreover, significantly better flotation of all copper sulphides and pyrite with marcasite was observed, in comparison with flotation test using collector and frother only. Using dextrin as a single reagent does not affect beneficiation of examined concentrate. However, dextrin had not depressed galena particles. It can suggest that various factors can influence on good flotation of galena, e.g. associations with other sulphides, mineral composition and structure of examined feed.

Role of pH on the adsorption of xanthate and dithiophosphinate onto galena

ABSTRACTIn the concentrators of a Mexican mining company has been observed that the pH of the flotation has a significant effect on the galena recovery: the increase of pH from 7.5 to 9.5 in the Pb/Cu flotation circuit, resulted in a decrease of about 10% of lead recovery. In the present investigation, experimental models and techniques were developed to study the effect of pH on xanthate and di-isobutyl dithiophosphinate adsorption onto galena. The results obtained by UV / Vis spectroscopy showed that once galena surface has been slightly oxidised by the dissolved oxygen of the aqueous suspension, adsorption of both surfactants increases significantly, being adversely affected by the increase of pH from 5.5 to 9.5. Microflotation measurements performed for both surfactants support these findings. Thermodynamic simulation of the system suggests that the observed behaviour is due to the nature of the solid species formed on the galena surface at the particular pH: lead sulfate (PbSO4) under neutral and slightly acid conditions, and the basic sulfate (2PbO·PbSO4) under neutral and slightly alkaline conditions, as well as to their respective solubility. Infrared spectrometry confirmed the occurrence of sulfate onto galena particles, with a higher concentration for the acid pre-conditioning compared to the alkaline pre-conditioning.

Effect of particle size on the oxidation and flotation behavior of galena particles

Effect of particle size on the oxidation and flotation behavior of galena particles

Real-time monitoring of entrainment using fundamental models and froth images

In this study, entrainment monitoring algorithms were developed, trained and implemented on the batch flotation of three synthetic mixtures of galena and quartz with different particle size ranges for the quartz mineral. An online image-based soft sensor framework was developed to estimate product grade and recovery using support vector regression. A dynamic fundamental model was developed with emphasis on the entrainment and drainage sub-processes. The model was reconciled with online soft sensor measurements and was updated in real-time by estimating the states and parameters using an extended Kalman filter. Along with the online measurements of quartz entrainment recovery, measurements of entrainment and the true flotation contribution for galena particles were obtained in real-time. The proposed monitoring framework was shown to be effective in monitoring entrainment and the grade and recovery of the desired minerals.