Flotation Rate Research Articles

On the selection of the coarsest size class in flotation rate characterizations

This paper studies size-by-size batch flotation kinetics for the separation of Cu at particle sizes +75 μm, investigating the responses in the -150/+75 μm, -212/+150 μm, -300/+212 μm, -355/+300 μm and +355 μm size fractions. The kinetic results were analyzed to identify classes limited by the maximum achievable recovery or low flotation rates. Combinations of these classes were investigated, emulating the selection of the coarsest size in a kinetic study. The impact of compositing size classes was discussed, emphasizing implications in the identification of difficult-to-float components. The -212/+75 μm classes reached steady recoveries at long flotation times, whereas the -355/+212 μm classes presented sustained increasing recoveries at extended flotation times. Flotation rate distributions in the -212/+75 μm classes exhibited mound-shaped distributions, indicating low fractions of rate constants close to zero (R∞-limited case). Conversely, the -355/+212 μm classes presented reverse J-shaped distributions, with a high fraction of valuable minerals with flotation rates close to zero (rate-limited case). Combining several size classes in the definition of the coarsest size fraction in kinetic characterizations proved to hide the flotation patterns of the less massive constituents (+212 μm classes). The +75 μm and +150 μm cumulative retained classes trended towards steady recoveries, consistently leading to mounded flotation rate distributions. This study highlighted the need for reliable methodologies to select size fractions in kinetic characterizations, as their arbitrary definitions may lead to a misinterpretation of the mineral losses when compositing classes with different flotation responses.

Effect of energy input on flotation of particles with different sizes: Perspective of hydrodynamics characteristics

By employing a torque sensor to measure energy input in a flotation machine, this paper investigates the flotation behavior of modified quartz particles with different sizes but similar surface hydrophobicity under various energy input conditions. Numerical simulations of the mechanical flotation machine were conducted to obtain the fluid dynamic characteristics including the flow velocity, turbulence kinetic energy, and turbulent eddy scale. With the flotation results and numerical simulations combined, the potential collision, attachment, and detachment behaviors of fine particles (―45 µm), intermediate particles (45―74 µm), and coarse particles (74―125 µm) were analyzed. The results demonstrate that under different conditions of energy input, the recovery of intermediate-sized particles was optimal for the above size fractions. As the particle size increases, the energy input required to achieve optimal recovery decreases. The flotation rate constants increase nearly linearly with energy input. Compared to the medium-sized particles in the range of 45―74 µm, finer and larger particles exhibit lower floatability. When the energy input exceeds a certain range, no stagnation zone is observed. The rupture of bubble-particle aggregates becomes more pronounced, which may be a reason why flotation recovery begins to decrease. Increasing energy input enhances turbulence energy dissipation and reduces the Kolmogorov turbulence length scale, in this study, the ―45 µm, 45―74 µm, and 74―125 µm particle sizes reached the optimal flotation performance at dp / η values of 1.35, 1.83, 2.54, respectively. The particle diameter-to-integral length scale ratio (dp/L) is also discussed as an important parameter for turbulent dispersion.

Effect of Nanobubbles on the Flotation Behavior of Microfine-Grained Serpentine

At present, scholars mainly study the relationship between nanobubbles and useful minerals, often ignoring the influence of bubbles on fine gangue minerals. When selecting nickel sulfide ore, scholars often faced with mudded and irrepressible serpentine, which seriously affects the quality of the concentrate. This mudded serpentine mineral often enters foam products with bubbles. In this study, the role of nanobubbles in the flotation behavior of hydrophilic serpentine was examined. Nanobubbles were successfully prepared via ultrasonic cavitation, with sizes ranging from 50 to 250 nm. The size and number of bubbles produced at 1 min and 2 min of sonication were significantly better than those of the prolonged test group, and it was found that longer sonication time did not produce better results. The stability of the nanobubbles produced via ultrasound was studied, and it was found that the nanobubbles were stable, with no change in size and only a slight decrease in number as the resting time increased. Nanobubbles were introduced into serpentine flotation, we found that the presence of nanobubbles significantly reduced the flotation recovery of serpentine. The presence of nanobubbles reduced the froth entrainment rate of microfine-grained serpentine, which in turn reduced its flotation rate. In the depressant group trials, it was found that the nanobubbles also reduced the amount of depressant. In short, the presence of nanobubbles can prevent the floating of fine hydrophilic gangues during flotation.

Технология использования чернового концентрата в качестве минералов-носителей

Технология использования чернового концентрата в качестве минералов-носителей

Optimized Apparatus Design for Continuous Aqueous Two-Phase Flotation (ATPF)

Aqueous two-phase flotation (ATPF) is an integrative downstream method for separating and concentrating biomolecules from crude biosuspensions such as fermentation broth. Its continuous operation not only increases throughput, but also makes it recommended for continuous upstreams. In this work, an optimized apparatus design in the form of a horizontal flotation tank is presented. The geometry of the new apparatus for continuous ATPF is optimized using flow simulations so that the two aqueous phases can be pumped uniformly through the flotation tank in co-current or counter-current flow. The implementation of a conductivity measurement enables to characterize the phase mixing effect induced by the rising gas bubbles introduced through three different gassing units. ATPF experiments with the model enzyme phospholipase A2 show that there are favorable combinations of gas flow rates to increase the flotation rate and reduce the back-diffusion at the outlet of the apparatus. This allows high phase exchange rates up to 2/h and hence increases the amount of enzymes that can be recovered per time. Co-current operation of continuous ATPF increased separation efficiency about 14% up to E = 74% compared to counter-current operation.

Study on the effect of flocculation morphology on the floatability of talc flocs and the adhesion mechanism with air bubbles

This study investigates the impact of floc morphology on flotation by preparing two types of flocs with similar apparent particle sizes but different aggregation degrees through varying the stirring speed. Flotation tests were conducted on the two flocs, revealing that flocs with higher aggregation degrees demonstrated superior floatability and higher flotation rate constants. Fractal dimension and AFM analysis indicated that flocs with higher aggregation degrees exhibited higher fractal dimensions, displaying a more circular and compact overall morphology, as well as a more regular and uniform surface morphology. XPS and contact angle tests showed that, for flocs with comparable particle sizes, an increase in fractal dimension led to increased adsorption of flocculant (PEO) on the surface, accompanied by enhanced hydrophobicity. Further analysis of the induction time for particle-bubble attachment and coverage angle demonstrated that flocs with higher fractal dimensions had shorter induction times and larger coverage angles, indicating faster attachment between flocs and bubbles. These findings suggest that flocs with higher fractal dimensions can acquire greater kinetic energy in a flow field, enabling them to more effectively disrupt the hydration film on the bubble surface and adhere to the bubble surface, thereby enhancing floatability.

A study on the desulfurization of sulfidic mine tailings for the production of a sulfur-poor residue

The mining industry generates large amounts of tailings every year. The most common destination for the tailings is deposition in tailings storage facilities (TSFs), which can have enormous dimensions. The management and storage of such large volumes of material pose many challenges in terms of dam stability and immobilization of hazardous contaminants that represent human-health and environmental risks, particularly for sulfide-containing materials. In addition, considerable amounts of precious and base metals can be lost in the tailings. Due to the economic value and growing industrial demand for precious and base metals, tailings may therefore be potential sources of secondary raw materials. This contribution investigates the flotation of pyrite-rich tailings, containing residual chalcopyrite, galena, and sphalerite, and high amounts of ultrafine particles. Flotation was used to recover the sulfide minerals and generate tailings with low sulfur content. The Cu-Pb-Zn-rich product could go to further treatment (e.g. (bio)hydrometallurgy) to recover the metals, while the low sulfur fraction could be used in the civil construction industry. Automated mineralogy (MLA) was used to provide quantitative mineralogical and textural data. Bench-scale experiments were performed by combining classic flotation and floc flotation (flotation of flocs of targeted minerals). Flotation of the material as received, as well as after classification into two fractions was performed. The samples as received and the coarser fraction (+37 µm) underwent classic flotation, while the finer fraction (−37 µm) was processed either by using the classic or the floc flotation approach. The flotation of the coarser particles provided higher sulfide recoveries, higher combined Cu-Pb-Zn grades in the concentrate (3.66%), cleaner residues (1.6% S), faster flotation rates, and reduced reagent consumption. Likewise, the results from the fine particle flotation allowed lower S content in the residues (3.4% S) as compared to the flotation of the original material. The results of the use of floc flotation for the finer fraction show an increase in the mass pull with a slight increase in the recovery of sulfides. Overall, the development of a route to process the tailings proved to be promising and the use of a two-route approach indicates advantages as compared to a single route.

Improving the performance of a low-grade porphyry copper ore flotation plant using a simulator that can predict grade vs. recovery curves

A large porphyry copper flotation plant has been simulated using a flotation model developed from first principles using the hydrophobic force as a kinetic parameter (Huang et al., 2022; Gupta et al., 2022). The input to the simulation was the size-by-class liberation matrix (mij) of a flotation feed, which was essential for predicting the size-by-class flotation rate constants (kij) and hence grade vs. recovery curves for the flotation bank. The model can be used to predict the performance of a flotation circuit provided that mij matrices are available for the feeds to the flotation banks in the circuit. With limited information on feed characteristics, we carried out a circuit simulation of the plant with some simplifying assumptions. The results suggest that significant financial benefits can be gained by recovering the slow-floating particles from the cleaner-scavenger tails that constitute the circulating load using an advanced separation technology in a separate copper recovery unit. With this approach, it is possible to substantially increase the throughput while maintaining copper recoveries and concentrate grades.

Effects of a cyclonic microbubble flotation column operating parameters on coal process responses

ABSTRACT Processing fine and ultrafine coal particles from primary resources is essential for sustainable development. As one of the most recently developed enrichment equipment, cyclonic microbubble flotation columns (FCMC) showed high efficiency in upgrading various fine minerals. However, understanding the effect of FCMC operating variables on coal upgrading process responses remains a black box and needs fundamental assessments. To fill the gap, this study examined the influence of circulating pump pressure and froth height on the recovery of different coal particle size ranges to assess and explore fundamental FCMC performance. The experimental results established that increased froth height would simultaneously reduce the collection and froth recovery. Coarse particles in the high froth height were detached due to bubble coalescence or rupture, while the liquid drainage reduced fine particle pollution of froth products. Increasing circulating pump pressure would increase the collection zone’s turbulence, lead to coarse particle detachment, and reduce collection recovery. Meanwhile, increasing circulating pump pressure could promote froth stability and decrease froth detachment in the froth zone. The calculated first-order rate constant (k c) confirmed that the flotation rate constants of coarse (−0.5 + 0.25 mm) and fine (−0.074 mm) particles were low, while the intermediate particles (−0.125 + 0.074 mm) had faster flotation kinetics.

Investigating the selective flotation of auriferous arsenian pyrite from refractory ores using thionocarbamate

Thionocarbamate, specifically modified Isopropyl Ethyl Thionocarbamate (IPETC) is selective in the separation of pyrite from arsenopyrite, following copper activation. In this work, the flotation response of a refractory gold (Au) ore containing arsenic (As) mainly in the form of arsenian pyrite is investigated to reject gold-barren sulphidic phases. The recovery of Au increased with an increase in CuSO4 concentration to 0.3 kg/t, beyond which further increase in concentration yielded no significant recovery. Variations of IPETC concentration between 0.2 and 1.5 kg /t of ore influenced both gold and arsenic recovery. It was surmised that the high collector dosage may have resulted from competitive adsorption between arsenian pyrite and other gangue minerals in the ore. 0.3 kg/t CuSO4 and 1.2 kg/t IPETC concentration at pH 11 gave the best results of 86% Au and 83% As recovery at an Au and As grade of 8.14 g/t and 2436 ppm respectively. LA-ICP-MS analysis of the concentrate showed a positive correlation between gold and arsenic. The technique also revealed arsenic-rich zones in pyrite which was further confirmed by SEM/BSD imaging to be rims of arsenian pyrite encapsulating Au-barren pyrite. MLA mineral maps of concentrates obtained at different times also showed that there is no relationship between the arsenic content of pyrite and the flotation rate. The deportment of arsenic in the rims of pyrite presents a complex mineralogical association which results in a decrease in concentrate grade.

Insight into anionic and cationic flotation discrepancy of quartz with altered surface roughness by acid etching

Surface roughness has a significant effect on mineral flotation. In this study, the surface roughness of quartz was altered using HF etching and their values before and after acid etching were quantified using AFM. Anionic flotation experiments with CaCl2 as activator and sodium oleate (NaOL) as collector, and cationic flotation experiments with dodecyl trimethyl ammonium chloride (DTAC) as collector were carried out for both the raw and acid-etched samples. The results showed that acid etching is beneficial to increase the surface roughness of quartz. The rougher quartz particle has higher recovery and quicker flotation rate during anionic flotation, while lower recovery and slower flotation rate during cationic flotation. The role of surface roughness in the discrepancy of these two flotations was investigated in terms of surface chemistry by X-ray photoelectron spectroscopy, UV spectrophotometer, surface force tensiometer, and zeta potential analyzer. The rougher sample was confirmed to have more unsaturated interfacial active sites, adsorbed more Ca2+ and NaOL, and exhibited higher hydrophobicity in anionic flotation. Differently, the rougher sample was verified to have less interfacial negative charge, adsorbed less DTAC, and exhibited weaker hydrophobicity in cationic flotation. Taken together, the surface roughness altered by acid etching has different effects on the adsorption capacity of NaOL and DTAC, thus affecting the wettability and floatability of quartz particles inconsistently in anionic and cationic flotation.

Effects of particle size on the flotation behavior of coal slime

In order to investigate the influence of particle size on the flotation behavior of coal slime, industrial analysis, elementary analysis, and particle size composition analysis were carried out on coal slime. The coal slime is divided into three sizes: −0.5 + 0.25, −0.25 + 0.074, and −0.074 mm, and full −0.5 mm particle sizes. Through contact angle measurement, wetting heat measurement, and step-by-step release test to investigate the hydrophobicity of each particle size; in addition, the flotation kinetics test of different particle sizes coal slime was also carried out. The results show that the particle size has a significant effect on the flotation behavior of fine coal slime. The medium particle size −0.25 + 0.074 mm has the best hydrophobicity, followed by −0.5 + 0.25 mm, again −0.5 mm, and finally −0.074 mm particle sizes. Use Origin software to fit six kinetic models to the test data of coal slime flotation kinetics, and analyze the maximum combustible recovery [Formula: see text], flotation rate constant (k), and correlation coefficient ([Formula: see text]) of each particle size, The results show that the first-order model with rectangular distribution of floatabilities can better describe the flotation of coal slime of each particle size.

Study on effect of nanobubble on ultra-fine flake graphite (UFG) flotation

Traditional flotation bubbles with large in size and small in specific surface area have low mineralization efficiency for fine particles in flotation, which makes it difficult to recover ultra-fine particles. Nanobubble flotation and traditional flotation of ultra-fine graphite (UFG) were studied in the study. The effects of nanobubble flotation and conventional flotation on UFG were stated by laser particle size analyzer, optical microscope and flotation kinetics test. The results show that the hydrophobic aggregates of UFG in nanobubble flotation system show floc morphology, increase the average size of hydrophobic aggregates by 17.31 µm, and effectively recover finer graphite particles compared with traditional flotation. In addition, the minimum particle size of nanobubble flotation concentrate (NFC) is 1 µm, while the traditional flotation concentrate (TFC) is about 18 µm, nanobubble flotation enhances recovery effect of UFG. More importantly, nanobubble flotation not only significantly improves the flotation rate of UFG but also increases the grade and recovery of UFG.

Exploring the effect of pulp aeration and lime-aid grinding on pyrrhotite-rich type copper sulfide ore flotation separation

The traditional high alkaline process (HAP) always encounters challenges in handling pyrrhotite-rich type copper sulfide ore, especially the slow copper flotation rate and the unsatisfactory separation efficiency. In this study, HAP was optimized via pulp aeration and lime-aid grinding, and their beneficial effect was studied systematically. Mineralogical study revealed that the lost Cu in tailings was coarse-grained chalcopyrite with sufficient liberation, confirming traditional HAP was not suitable for the processing of this type ore. Batch flotation tests revealed that the flotation rate and the upper limit of Cu recovery of traditional HAP were very poor, but pulp aeration and lime-aid grinding accelerated chalcopyrite flotation significantly and further increased the upper limit of Cu recovery from 74.6% to 90.0%. Industrial tests further confirmed that the optimized process was suitable for this pyrrhotite-rich type copper sulfide ore in Dongguashan Dressing Plant, and the recovery of Cu increased from 79.8% to 87.7%, significantly. The optimized process not only break through the technical bottlenecks of traditional HAP but bring an additional profit of 207 million yuan per year approximately. Therefore, pulp aeration and lime-aid grinding were expected for widespread application in the beneficiation of pyrrhotite-rich copper mines.

Effects of Different Grinding Media and Milling Conditions on the Flotation Performance of a Copper-Pyrite Ore

Different milling conditions, such as wet or dry, and use of different grinding media have a great impact on the flotation performance of sulphide minerals. In the present study, the effects of wet and dry grinding and the use of different grinding media, such as mild steel (MS) and stainless steel (SS), were investigated on a Cu-sulphide ore. The samples were ground as dry and wet with both grinding media, to a P80 value of −75 µm, and then flotation was carried out under the same conditions. The obtained data from flotation were evaluated in terms of solid/water recovery, chalcopyrite/pyrite recovery and separation efficiency. The effects of different milling conditions were discussed with the measured chemical parameters such as redox potential and dissolved oxygen level together with the flotation rate of chalcopyrite. The redox potential of the dry ground ore, irrespective of the type of milling media, was measured considerably higher than the wet grinding conditions. With SS media flotation, the rate of Cu was high for dry grinding, resulting in a higher selective concentrate in terms of grade. However, Cu recovery was lower due to the instability of the froth structure. Separation efficiency pointed out that the best flotation performance could be obtained using a wet grinding condition with MS balls.

Adhesion between nanobubbles and fine cassiterite particles

Adhesion is an important process of particle-bubble interaction in fine particle (−10 μm) flotation. This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a high-speed camera, atomic force microscope (AFM), adsorption capacity tests, and induction time tests. After being pretreated with nanobubbles (NBs) water, fine cassiterite particles flotation tests were carried out using caprylhydroxamic acid (CHA) as a collector. The results showed that NBs can improve the recovery and flotation rate of fine cassiterite while decreasing the collector dosage. The adsorption capacity test indicated that the cassiterite treated with NBs had lower demand for collector concentration. The AFM imaging results further demonstrate that NBs could reduce the adsorption of CHA on the surface of minerals. Since NBs played a part of the role of collector, it can improve the flotation effect while reducing the amount of collector. The induction time test and the high-speed camera observation test showed that NBs promoted the attachment between bubbles and cassiterite particles. On the other hand, NBs agglomerate cassiterite particles, increasing the probability of particles colliding with bubbles.

Enhancement of ultrafine coal slime flotation using high-shear pretreatment and polyvinylpyrrolidone

ABSTRACT Flotation has been used to treat coal over the last century. However, the conventional flotation condition can hardly be applied to ultrafine coal slime (UCS). An alternative combined method, which has the potential to improve UCS separation efficiency, is using high-shear pretreatment (HSP) and polymer regulator. Presented in this paper are the findings from an investigation into the flotation performance and aggregate characteristics of UCS with the assistance of HSP and polyvinylpyrrolidone (PVP). Electrokinetic, laser particle size, and rheology experiments were employed to analyze the influence of HSP and PVP on ultrafine particles. The UCS studied has a high ash content of 53.62%. The flotation results were analyzed through flotation efficiency and selectivity indexes. The results show that the flotation concentrate has less gangue entrainment and high combustible recovery, low ash content (12.74%) and higher flotation efficiency (66.26%) were obtained. Moreover, the results of flotation kinetics illustrate the advantage of using PVP, which improves the cumulative combustible recovery and flotation rate. The introduction of HSP was conducive to the improvement of separation selectivity. These findings provide fundamental insights into the effect of HSP and PVP on ultrafine particles and offer an effective technique for the enhancement of UCS flotation.

Selective Adsorption of Sodium Silicate on the Surface of Bastnaesite and Fluorite in Salicylhydroxamic Acid System under Alkaline Conditions

During the flotation separation process of bastnaesite, it is difficult to separate bastnaesite from fluorite effectively. In this present study, sodium silicate (SS) can effectively improve the flotation separation effect of bastnaesite and fluorite in salicylhydroxamic acid (SHA) systemasa. Through relevant analyses, such as Zeta potential measurements, adsorption capacity tests, Fourier transform infrared (FTIR) spectroscopic analyses and X-ray photoelectron spectroscopy (XPS) tests, the selective suppressor of SS on fluorite was proven. At pH 10, the single mineral flotation results show that with the increase of SS dosage, the flotation recovery of fluorite rapidly decreases from 61.5% to 35.31%, while the flotation rate of bastnaesite is still high (recovery is 80.02%). Then, the experiment of artificial mixed ore proved that the flotation separation of fluorite and bastnaesite was effective under the appropriate dosage of inhibitor. The results of potentiodynamic measurement and an adsorption capacity test showed that the SiOOH3− structure of SS more easily reacted with fluorite, which further prevented the adsorption of SHA on the fluorite surface. FTIR test results and XPS analysis further showed that SS had a strong binding effect with the Ca site on the fluorite surface, but a weak binding effect with the Ce site on the bastnaesite surface. Consequently, SS can be used as an effective inhibitor in the flotation separation of fluorite and bastnaesite.

Determination of three stages for molybdenite flotation kinetics in seawater

ABSTRACT This research mainly investigated the flotation kinetics of molybdenite in seawater based on four flotation models. Molybdenite flotation presented an excellent agreement with the first-order model with rectangular distribution. The ultimate cumulative recovery (R ∞) and flotation rate constant (k) of molybdenite decreased in seawater, mainly due to the divalent cations, with the impact of Mg2+ being significantly greater than that of Ca2+. The addition of sodium silicate (SS) and sodium hexametaphosphate (SH) increased the flotation recovery and rate, probably due to the positive role of dispersants on preventing the attachment of seawater precipitates onto molybdenite surface. In addition, three different stages of flotation kinetics were proposed to reveal the molybdenite flotation for the first time, with the highest flotation recovery and rate being found at Stage I. However, seawater showed a negative role on Stage I, i.e. resulting in a longer duration and lower recovery, as compared to that in pure water. The addition of both SS and SH improved the flotation kinetics at Stage I, with SH being more significant. Therefore, it is more feasible to eliminate the negative effects of seawater on molybdenite flotation at the initial stage (Stage I).

Effect of Solid Concentration and Particle Size on the Flotation Kinetics and Entrainment of Quartz and Hematite

Despite the importance of solid concentration in froth flotation, its effect on flotation kinetics and entrainment has rarely been studied. In this study, the flotation kinetics and entrainment in quartz and hematite single-mineral flotation systems as a function of the solid concentration and particle size were investigated using dodecylamine acetate as a collector. Kinetics modeling showed that the Gamma distribution achieved the best agreement with the experimental data, whereas the Classical and Klimpel models poorly fit the data (e.g., RMSE). The flotation rate constants (k) of both quartz and hematite at a higher solid concentration showed a concave shape, with the inflexion point at the middle-size range, whereas this trend altered at lower solid concentrations. Overall, quartz exhibited higher equilibrium recoveries (R∞) than hematite, which indicates its better overall rate constants. The degree of water recovery in both the quartz and hematite systems was higher at higher solid concentrations, but the hematite system exhibited higher water R∞ than the quartz system, meaning that the entrainment of gangue could be higher in direct hematite flotation than the reverse one. Therefore, a higher solid concentration is associated with better overall quartz recovery and can reduce hematite loss by entrainment during reverse flotation. An inverse relationship was identified between the solid concentration and particle size in terms of the ratio of water recovery to the concentrate. In the reverse flotation of iron ore, refraining from achieving equilibrium recovery could help limit entrainment, but this was not necessarily the case in direct flotation. No entrainment model or method other than the Warren and Ross model approximated the overall trends of flotation at the finest size range (−38 µm). However, extending the Warren method to polynomial distribution led to an improved fit with the experimental results. In addition to the solid concentration, particle density and size were revealed to be key to developing new entrainment models. Finally, after the fast recovery period (true flotation) was over, the slow recoveries were mainly driven by the slow-floating water fraction.