Flotation Performance Research Articles

Adsorption Behavior and Wettability of Rhodochrosite Surface: Effect of C18 Fatty Acid Unsaturation

Mineral surface wettability and its regulation by the adsorption of collectors have an important influence on the flotation performance. The adsorption behavior of C18 fatty acid with different unsaturation and its effect on rhodochrosite wettability was investigated with surface tension, contact angle, and atomic force microscopy (AFM) measurements. The results indicated that rhodochrosite hydrophobicity increased with the increasing concentration of fatty acid, along with the maximum contact angle (θmax) between hemimicelle concentration (HMC) and critical micelle concentration (CMC). Oleic acid (OA), linoleic acid (LA), and α-linolenic acid (ALA) had a higher θmax than stearic acid (SA), but the value decreased with the increase of C=C bond number. Besides, preferential adsorption of unsaturated fatty acids on the liquid-air interface can be attributed to the molecule’s steric hindrance resulting from C=C double bond, and the θ kept almost invariant with a higher value of ΓLG than ΓSL until HMC. The oriented monolayer and bilayer structure of fatty acids formed gradually on rhodochrosite surface with increasing concentration. However, the θmax may not necessarily correspond to the beginning of bilayer formation. Cylindrical monolayer and bilayer micelles of SA molecules were observed on rhodochrosite surface at HMC and CMC, respectively. While bilayer structures of unsaturated fatty acids formed before complete coverage of monolayer on rhodochrosite surface because of surface heterogeneity. This work provided a good understanding on the adsorption mechanism of fatty acid on rhodochrosite for flotation.

Synergistic collection mechanism of D-phenylalanine and sodium oleate in flotation of diaspore from kaolinite

Mixed collectors were widely used in mineral flotation. In this work, D-phenylalanine (D-phe) was first introduced to improve the collectability and selectivity of sodium oleate (NaOL) for diaspore from kaolinite. The flotation performance of diaspore and kaolinite were studied by micro-flotation tests, and the synergistic mechanisms of D-phe with NaOL were investigated through FTIR spectra, zeta potential, solution chemistry and X-ray photoelectron spectroscopy (XPS). Single and mixed flotation results show that D-phe exhibited superior synergism power with the NaOL collector. Under pulp pH 9.0, the flotation recovery of diaspore was increased from 77.13% to 91.07%, while that of kaolinite was decreased from 16.27% to 13.75%. The zeta potential and XPS analysis indicate that the synergistic mechanisms of D-phe with NaOL were mainly the co-adsorption via the carboxylate group of D-phe and NaOL bonding with the Al sites of diaspore surface. D-phe was chelated onto the diaspore surface through the –COO– and –NH3+/NH2 groups, and the pre-adsorption of D-phe could increase the Al active sites of diaspore surface for the direct adsorption of NaOL. NaOL could also indirectly adsorb on the diaspore surface through H-bonding with –NH2/NH3+ groups of D-phe.

Flotation performance and adsorption mechanism of novel 1-(2-hydroxyphenyl)hex-2-en-1-one oxime flotation collector to malachite

Abstract A novel collector 1-(2-hydroxyphenyl)hex-2-en-1-one oxime (HPHO) was synthesized from 2-hydroxy acetophenone and butyraldehyde. Its flotation performance and adsorption mechanism to malachite were investigated by flotation test, zeta potential, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis techniques. Compared with benzohydroxamic acid (BA), 1-(2-hydroxyphenyl)ethan-1-one oxime (HPEO) and sodium isobutyl xanthate (SIBX), HPHO exhibited excellent collecting power to malachite without additional reagents, such as Na2S regulator and methyl isobutyl carbinol (MIBC) frother. Results of zeta potential indicated that HPHO was coated on malachite surfaces through a chemisorption process. FTIR and XPS data gave clear evidence for the formation of Cu–oxime complex on malachite surfaces after HPHO adsorption through the linkage between C=C, –OH, N–OH group and Cu species.

Comprehensive utilization of foundry dust: Coal powder and clay minerals separation by ultrasonic-assisted flotation

Clay sand casting generates a large amount of foundry dust (FD), and the presence of coal powder in the FD makes it difficult to recycle and utilize. The landfill of the FD creates a serious environmental pollution and wastes a valuable resource. To improve the above situation, the FD was analyzed and characterized by X-ray fluorescence spectrometer (XRF), X-ray diffraction (XRD) and electron probe microanalyzer (EPMA). An ultrasonic-assisted flotation process was developed for the comprehensive utilization of the FD, and the effects of ultrasonic time on the flotation performance and flotation kinetics were investigated. In addition, the two-stage flotation of the FD was conducted. Obtained results showed that the FD mainly consisted of coal powder and clay minerals, and the coal powder was covered by clay minerals. The separation efficiency of the coal powder and clay minerals can be significantly enhanced by ultrasonic pretreatment, and the optimal ultrasonic time was 30 min. The flotation kinetics analysis results indicated that the first-order model with rectangular distribution was more reasonable for the data fitting of the ultrasonic-assisted flotation. Furthermore, the concentrate and tailings obtained by the two-stage flotation had achieved an acceptable result, favoring the comprehensive utilization of the FD.

Ti3O5 and Al2TiO5 Crystals Flotation Characteristics from Ti-bearing Blast Furnace Slag: A Density Functional Theory and Experimental Study

Anosovite crystalline is an ideal mineral for flotation from the Ti-bearing blast furnace (TBBF) slag. Ti3O5 crystal and Al2TiO5 crystal are two kinds of anosovites, and the Al element significantly affects the electronic structure and flotation performance of anosovite. The floatability of Ti3O5 and Al2TiO5 crystals were studied by Mulliken populations, energy bands, and density of states (DOS). In addition, the flotation experiment of the two kinds of anosovite crystals (Ti3O5 and Al2TiO5) was conducted and proved that the density functional theory (DFT) calculation results were accurate. Compared with Ti3O5 crystal, the Fermi energy level of Al2TiO5 crystal shifts around 2 eV in a negative direction by DOS analysis, which is beneficial to flotation. And Al2TiO5 crystal possesses a larger value of bond population, which is 0.41, for Ti-O bonds than Ti3O5 crystal and the bond length of Ti-O in Al2TiO5 crystal is shorter, therefore Al2TiO5 crystal shows a stronger covalency. The changes of the Fermi energy level and the covalency bonds in Al2TiO5 crystal both demonstrated that doping the Al component into the Ti3O5 crystal was beneficial to improve the flotation effect. Moreover, the Al2TiO5 crystal had a higher flotation efficiency compared to the Ti3O5 crystal when the dosages of salicylhydroxamic acid (SHA) and sodium oleate were the same. Therefore, both DFT calculation and experiment show that the flotation effect of the Al2TiO5 crystal is better than that of the Ti3O5 crystal.

Fine Bauxite Recovery Using a Plate-Packed Flotation Column

In this investigation, the fine-grained bauxite ore flotation was conducted in a plate-packed flotation column. This paper evaluated the effects of packing-plates on recovering fine bauxite particles and revealed the fundamental mechanisms. Bubble coalescence and break-up behaviors in the packed and unpacked flotation columns were characterized by combining Computational Fluid Dynamics (CFD) and Population Balance Model (PBM) techniques. Flotation experiments showed that packing-plates in the collection zone of a column can improve bauxite flotation performance and increase the smaller bauxite particles recovery. Using packing-plates, the recovery of Al2O3 increased by 2.11%, and the grade of Al2O3 increased by 1.85%. The fraction of −20 μm mineral particles in concentrate increased from 47.31% to 54.79%. CFD simulation results indicated that the packing-plates optimized the bubble distribution characteristics and increased the proportion of microbubbles in the flotation column, which contributed to improving the capture probability of fine bauxite particles.

Density Functional Theory and XPS Studies of the Adsorption of Cyanide on Chalcopyrite Surfaces.

In this work, both the density functional theory (DFT) calculation and X-ray photoelectron spectroscopy (XPS) were conducted to investigate the depression mechanisms of cyanide on the flotation performance of chalcopyrite. The density functional theory calculation results showed that cyanide could be adsorbed on a chalcopyrite (112) surface spontaneously, which preferably occurred on the surface Fe–Fe hollow site. Both C and N atoms of cyanide could bond with Fe atoms of the chalcopyrite (112) surface, while the interaction of Fe–C bond was more intense, where the Fe 3d orbital donated electrons to the hybrid sp orbital of a C atom forming a back-donating bond. XPS analysis indicated that the chemical interaction between cyanide and surface Fe atoms occurred, resulting in the generation of a hydrophilic iron–cyanide complex on the chalcopyrite surface, which deteriorated the flotation performance of chalcopyrite.

Influence of impeller speed and cell volume on coal flotation performance in a self-aerating flotation machine

The effect of impeller speed and cell volume on batch coal flotation performance in a self-aerating flotation machine is studied in the present investigation. Factorial designed experiments are carried out to establish the relationships between the manipulated variables (impeller speed, and cell volume, and their interactions) with the separation indicators (yield, ash, combustible recovery and entrained water recovery). Correlation coefficient values are used to select the best fit model, and an analysis of variance to identify the statistically significant components of the model. The results indicated that both the impeller speed and cell volume significantly influence the performance of coal flotation. Further, the influence of these variables and their significance is discussed by flotation rate constant.

Hydrophobic intensification flotation: Comparison of collector containing two minerophilic groups with conventional collectors

The surface hydrophobization and flotation of a xanthate−hydroxamate collector toward copper oxide mineral were compared with the combined collectors of xanthate and hydroxamate through water contact angle (WCA) and micro-flotation experiments. The results showed that S-[(2-hydroxyamino)-2-oxoethyl]-O-octyl-dithiocarbonate ester (HAOODE) exhibited stronger hydrophobization and better flotation performance to malachite (Cu2(OH)2CO3) than octyl-hydroxamic acid (OHA) and its combination with S-allyl-O-ethyl xanthate ester (AEXE). To understand the hydrophobic intensification mechanism of HAOODE to malachite, zeta potential, atomic force microscopy (AFM) and XPS measurements were carried out. The results recommended that malachite chemisorbed HAOODE to form Cu—HAOODE complexes in which the hydroxamate—(O,O)—Cu and —O—C(—S—Cu)—S— configurations co-existed. The co-adsorption of HAOODE's hetero-difunctional groups was more stable than the single-functional- group adsorption of OHA and AEXE, which produced the “loop” structure and intensified the self-assembly alignment of HAOODE on malachite surfaces. In addition, the “h” shape steric orientation of the double hydrophobic groups in HAOODE facilitated stronger hydrophobization toward malachite than the “line” or “V” hydrophobic carbon chains of OHA or AEXE. Thus, HAOODE achieved the preferable flotation recovery of malachite particles in comparison with OHA and AEXE.

Effect of particle size on magnesite flotation based on kinetic studies and machine learning simulation

This research focused on the effect of particle size and flotation time on magnesite flotation, and the flotation performance of various size fractions were predicted by a machine learning (ML) method. Four kinetic models were used to fit the recovery of MgO and SiO2 in various size fractions of magnesite flotation. The results demonstrated that the flotation of magnesite exhibits good agreement with the classical first-order kinetic model. Besides, the effect of various particle sizes on MgO recovery and selectivity index was predicted by ML method. It was shown that the proposed ML model could accurately reproduce the effects of particle size and flotation time on magnesite flotation performance. Furthermore, the developed model revealed that the optimal mean size range for magnesite flotation is 30 to 48 μm. Therefore, this paper is of great significance to the application of ML methods in the prediction of various magnesite size flotation performance.

Investigation of cell geometry effect on the turbulence characteristics and flotation performance using particle image velocimetry technique

The flow patterns and turbulence characteristics of the flow fields in a mechanical flotation cell have important effects on the hydrodynamic and metallurgical responses. In this study, the effect of cell geometry (off-bottom clearance (C), cell aspect ratio (H/T) and impeller diameter (D) on the turbulence properties and flotation performance using pure quartz particles of different sizes in a lab-scale Denver flotation cell was investigated. The results showed that the change in cell geometry changed the local turbulence characteristics. The change of C (from 0.2 T to 0.1 T), D (from T/2 to T/3) and H/T (from 1.2 to 1.5) did not change the flow pattern. The lower C was recommended to improve flotation performance. The larger D (T/2) was more useful for particle size of +38 μm. At the same Reynolds number, higher H/T is suitable for coarse particles, while lower H/T is recommended for particls size of −150 μm.

Assessing the Combined Effect of Water Temperature and Complex Water Matrices on Xanthate Adsorption Using Multiple Linear Regression

The combined effect of dissolved ions and water temperature on the adsorption of a xanthate collector on chalcopyrite and pentlandite was investigated using multiple linear regression. Cationic species improved the adsorption of the collector on sulphide minerals through xanthate adsorption activation. Thiosulphate ions generally had a negative effect on collector adsorption, and the interaction of thiosulphate ions and cations effectively reduced collector adsorption on the sulphide minerals. With regards to temperature variation caused by seasonal variation, this study suggests that temperature can influence the adsorption of collectors in the flotation process and this should be approached on a case by case basis as it seems to differ with the type of mineral under investigation. These fundamental results prompt a discussion on how complex water matrices can affect interactions of reagents and sulphide minerals at the solid–liquid interface and the possible effect on flotation performance.

Effect of air dissolved in water on simultaneous ultrasonic-assisted coal flotation

ABSTRACT The effect of air dissolved in natural water on simultaneous ultrasonic-assisted coal flotation was investigated combined with flotation tests, froth properties and flotation kinetics models analysis. Compared with degassed water, the better flotation performance was obtained in natural water when ultrasound was not used or ultrasonic power was lower than 200 W. For the low ultrasonic power (< 200 W), the air dissolved in natural water promoted the precipitation of bubbles to obtain the small bubble and thick froth layer, which was beneficial to improve the coal flotation. However, the froth properties in natural water were almost the same as those in degassed water if the ultrasonic power was reached to 200 W, indicating that the performance of ultrasonic flotation in degassed water was almost the same as that in natural water. In addition, the processes of ultrasonic-assisted coal flotation in natural and degassed water could be described by the second-order model with rectangular distribution of floatability. The ultrasonic flotation rate of natural water was twice than that of degassed water. Hence, these above results made a contribution to improve the performance of ultrasonic-assisted coal flotation in natural water.

Comparison Between Performance of Fluorite Flotation Under Different Depressants Reagents in Two Pieces of Laboratory Equipment

Fluorite is an important industrial mineral composed of calcium and fluorine (CaF2). This mineral is widely distributed through different deposits. However, in most cases, fluorite is tightly associated with gangue, such as calcite and quartz. In this paper, different depressants are tested in the flotation of fluorite in two different laboratory configurations—cell and column. Quebracho tree (QT) was tested as the main depressant in combination with white dextrin (WD), potato starch (PT), carboxymethyl cellulose (CMC), and sodium hexametaphosphate (SHMP). The optimum pulp pH of the flotation of fluorite was determined as approximately 9.5–10. The best results are obtained using a combination of quebracho and white dextrin as depressants, reaching 74% of fluorite grade for modified column flotation and 70.5% for cell flotation. Additionally, the metallurgical recovery obtained higher values when the flotation was carried out in the modified column and using the same combination of depressant agents—75% for modified column flotation and 60% for flotation cell.

First insights to the microbial communities in the plant process water of the multi-metal Kevitsa mine

Metallurgical processes demand large quantities of water. However, in many locations, water is becoming scarce and process water recycling is needed. Closing water loops can be challenging due to build-up of flotation chemicals, metal ions and microorganisms in the recycled water affecting the flotation performance. Here, we have characterized the microbial communities over a 2-month period in different locations of the multi-metal Kevitsa mine in Northern Finland, by microbiome sequencing, enumeration of bacteria, archaea and fungi by qPCR, and cultivation. The microbial communities showed high diversity, but were dominated by Alpha- and Gammaproteobacteria. In addition, various fungal taxa were detected, whereas the archaeal taxa were only sparsely detected from the sequence data. The number of bacterial 16S rRNA gene copies in Process water and Ni thickener overflow varied between 0.5–3.3 × 105 mL−1, whereas the Flotation tailings showed two orders of magnitude lower amounts. Fungi were present at 3.0 × 102–8.1 × 104 5.8S rRNA gene copies mL−1 in all samples, while the number of archaea fluctuated between 8.8 × 101–3.2 × 105 16S rRNA gene copies mL−1. The number of all microbial groups were generally lower in September than in August. When tested on 8 different cultivation media, the microorganisms generally responded positively to organic carbon, and were also shown to oxidize thiosulfate, which may indicate that build-up of organic flotation chemicals and sulfur species from the ore may cause the microbial numbers to increase. This study is part of the H2020 ITERAMS project (Grant agreement# 730480), which strives to improve the recycling of water and minimize the environmental impact of mines.

A Molecular-Scale Approach to Rare-Earth Beneficiation: Thinking Small to Avoid Large Losses.

SummarySeparating rare-earth-element-rich minerals from unwanted gangue in mined ores relies on selective binding of collector molecules at the interface to facilitate froth flotation. Salicylhydroxamic acid (SHA) exhibits enhanced selectivity for bastnäsite over calcite in microflotation experiments. Through a multifaceted approach, leveraging density functional theory calculations, and advanced spectroscopic methods, we provide molecular-level mechanistic insight to this selectivity. The hydroxamic acid moiety introduces strong interactions at metal-atom surface sites and hinders subsurface-cation stabilization at vacancy-defect sites, in calcite especially. Resulting from hydrogen-bond-induced interactions, SHA lies flat on the bastnäsite surface and shows a tendency for multilayer formation at high coverages. In this conformation, SHA complexation with bastnäsite metal ions is stabilized, leading to advanced flotation performance. In contrast, SHA lies perpendicular to the calcite surface due to a difference in cationic spacing. We anticipate that these insights will motivate rational design and selection of future collector molecules for enhanced ore beneficiation.

Effect of Nanobubbles on the Flotation Performance of Oxidized Coal.

In this study, the effects of air bubbles and nanobubbles on flotation performance and kinetics of oxidized coal were investigated. The surface properties of the coal sample before and after oxidation were characterized by a scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The nanobubbles on highly oriented pyrolytic graphite (HOPG) were observed by an atomic force microscope (AFM). The interaction between coal and conventional bubbles in the absence and presence of nanobubbles was explained by induction time. Flotation results showed that oxidized coal flotation in the presence of nanobubbles resulted in 10% higher combustible matter recovery than conventional air bubble flotation. Moreover, it was found that the flotation of oxidized coal in the absence and presence of nanobubbles can be best described using the first-order model with the rectangular model. AFM images analysis showed that a large number of nanobubbles were produced and attached to the oxidized coal surface. The induction times of the oxidized coal in the absence and presence of nanobubbles were 1000 and 39 ms, respectively, indicating that the existence of nanobubbles effectively promotes the interaction between oxidized coal and macroair bubbles. In addition, the agglomeration between oxidized coal particles also occurred spontaneously in the presence of nanobubbles, which was helpful in improving the combustible matter recovery and flotation rate of oxidized coal.

The formation of iron sulphide on oxidised pyrite during sulphidisation and subsequent interactions with xanthate

Pyrite can be partially or completely oxidised during the stockpiling of pyritic ores, leading to a poor flotation performance. Sulphidisation with potential control has been commonly practised to convert the oxidised pyrite surface into a sulphide form before flotation. However, the lack of agreement on the suitable potential for the formation of iron sulphide species on the oxidised pyrite surface makes this practice genuinely uncertain. Using electrochemical techniques, this work identified that it was only at a potential below −300 mV that the sulphidisation with Na2S could generate iron sulphide species on the oxidised pyrite surface. In order to have the newly sulphidised pyrite surface to react with xanthate, the potential had to be elevated to 100 mV, but the newly formed iron sulphide species started to oxidise at a potential of around −50 mV. These findings provide a fundamental understanding of the nature of sulphidisation of oxidised sulphide minerals and a guideline to improve their flotation.

Parametric Optimization in Rougher Flotation Performance of a Sulfidized Mixed Copper Ore

The dominant challenge of current copper beneficiation plants is the low recoverability of oxide copper-bearing minerals associated with sulfide type ones. Furthermore, applying commonly used conventional methodologies does not allow the interactional effects of critical parameters in the flotation processes to be investigated, which is mostly overlooked in the literature. To tackle this issue, the present paper aimed at characterizing the behavior of five key effective factors and their interactions in a sulfidized copper ore. In this context, dosage of collector (sodium di-ethydithiophosphate, 60–100 g/t), depressant (sodium silicate, 80–120 g/t) and frother (methyl isobutyl carbinol (MIBC), 6–10 g/t), pulp pH (7–11) and agitation rate (900–1300 rpm) were examined and statistically analyzed using response surface methodology. Flotation experiments were conducted in a Denver type agitated flotation cell at the rougher stage. The experimental results showed that increasing the pH (from 8 to 10) at low agitation rate (1000 rpm) enhanced the recovery from 80.36% to 85.22%, while at high agitation rate (1200 rpm), a slight declination occurred in the recovery. Meanwhile, increasing the collector dosage at a lower frother value (7 g/t), caused a reduction of about 4.44% in copper recovery owing to the interactions between factors, whereas at a higher frother level (9 g/t), the recovery was almost unchanged. The optimization process was also performed using the goal function approach, and maximum copper recovery of 92.75% was obtained using ~70 g/t collector, 110 g/t depressant, 7 g/t frother, pulp pH of 10 and 1000 rpm agitation rate.

A novel decyl-salicyl hydroxamic acid flotation collector: Its synthesis and flotation separation of malachite against quartz

In this study, a novel decyl-salicyl hydroxamic acid (DSHA) collector was synthesized and applied to a malachite flotation. Subsequently, its flotation performance on malachite was studied through micro- and batch-flotation tests, as well as through zeta-potential and X-ray photoelectron spectroscopy (XPS) analyses. The results of micro-flotation tests indicate that DSHA exhibits a powerful ability to collect malachite and a satisfactory selectivity against quartz. The batch-flotation tests also prove that DSHA is an effective collector for copper oxide ore. Furthermore, mixed collectors of DSHA and sodium isobutyl xanthate (SIBX) achieved a better selective separation of CuO than individual DSHA, SIBX, or salicyl hydroxamic acid (SHA). The results of a zeta-potential analysis infers that DSHA may chemisorb on malachite.The XPS analysis results provide clear evidence that DSHA adsorbs on malachite through the co-adsorption mode.