Talc Flotation Research Articles

The application of KMnO4 in reverse flotation separation of chalcopyrite and talc and its selective depression mechanism

Talc exhibits excellent floatability and, as a major silicate gangue mineral associated with chalcopyrite, significantly obstructs the purification and smelting of chalcopyrite. This study investigates the reverse flotation separation of chalcopyrite and talc using KMnO4 as a depressant and DDA (dodecylamine) as a collector within a reverse flotation system. Single mineral flotation experiments show that after adding KMnO4, the recovery of chalcopyrite in 38–74 μm is only 6.86 %, whereas the recovery of talc in 45–106 μm and 25–45 μm are 93.47 % and 89.25 %, respectively. Further experiments with artificially mixed ores demonstrate that KMnO4 effectively achieves the separation of chalcopyrite and talc. The depression mechanism of KMnO4 on chalcopyrite and talc was analyzed using Zeta potential, contact angle measurement, AFM (atomic force microscopy), FTIR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), and DFT (density functional theory) calculations. Mechanistic analysis indicates that in an alkaline environment, chalcopyrite can undergo a redox reaction with KMnO4, forming hydrophilic hydroxide species (Cu(OH)2, Fe(OH)3) on the chalcopyrite surface, which depresses chalcopyrite flotation. In contrast, the surface properties of talc are relatively stable and difficult to react with KMnO4, which cannot depress the flotation of talc. Therefore, KMnO4 can be used as an efficient and selective depressant for the reverse flotation separation of chalcopyrite and talc.

The selective adsorption mechanism of calcium ions/pullulan in the flotation separation of chalcopyrite from talc

The flotation separation of chalcopyrite from talc by use of pullulan and sodium butyl xanthate (SBX) under calcium ions was investigated in this study. The single mineral flotation shows that SBX collector had a good collecting ability for chalcopyrite while talc had a good natural floatability. The talc flotation was observably depressed while that of chalcopyrite was not affected in the presence of pullulan alone. With the addition of calcium ions. The depression of talc could be achieved with a small amount of pullulan. The artificial chalcopyrite/talc mixture flotation tests reveal that the addition of pullulan could realize the separation of chalcopyrite from talc in the absence and presence of calcium ions, and the dosage of pullulan with calcium ions was lower than that in the absence of calcium ions. Zeta potential measurements suggest pullulan was easily adsorbed onto the calcium ions treated talc surface, and the XPS tests further confirm that calcium ions could selectively adsorb onto the talc surface and increase its activated sites for hydrogen bonding with pullulan molecules. This study is expect to provide a novel polysaccharide depressant for the beneficiation of chalcopyrite from talc.

Upgrading of talc-bearing copper-nickel sulfide ore by froth flotation using sodium phytate as depressant

Copper-nickel sulfide ores, as important sources of copper and nickel metals, always have large amount of clay-type gangue minerals like talc. In this work, selective flotation of copper-nickel sulfide ore was achieved by using a selective depressant of sodium phytate. Microscale flotation results show that sodium phytate can selectively and effectively depress talc flotation, but has a minor effect on the floatability of chalcopyrite and pentlandite. In batch-scale flotation tests of feed ore, containing 0.35% Cu, 0.68% Ni and 24.57% MgO, potassium butyl xanthate was employed as the collector in rougher (200 g/t), scavenger-1 (100 g/t), scavenger-2 (50 g/t) and scavenger-3 (25 g/t), and sodium phytate depressant was used in rougher (300 g/t) and cleaner-1 (100 g/t) stages of closed-circuit flotation to obtain a concentrate containing 2.66% Cu (79.7% recovery), 5.38% Ni (83.01% recovery), and only 6.39% MgO. The contact angle analysis showed that sodium phytate significantly improved the hydrophilicity of talc, but it only slightly increased the hydrophilicity of chalcopyrite and nickelpyrite. The FTIR and XPS tests showed that chemisorption of sodium phytate occurred on talc surface by the interaction between P-O/PO and Mg active sites. This work indicates that sodium phytate has strong potential as an inhibitor for the selective separation of talc from copper-nickel sulfide ores.

Flotation behavior and surface adsorption mechanism of a novel selective inhibitor HDP in the separation of chalcopyrite and talc flotation

Chalcopyrite and talc exhibit strong natural hydrophobicity, making it challenging for conventional inhibitors to effectively separate the two through flotation. This paper proposes a novel starch-modified reagent, Hydroxypropyl distarch phosphate (HDP), for the separation of chalcopyrite and talc. Micro-flotation test results indicate that HDP has a significant inhibitory effect on talc, while the flotation recovery of chalcopyrite is almost unaffected. Effective separation of chalcopyrite and talc can be achieved with the addition of only 5 mg/L of HDP. Zeta potential, adsorption amount, and FTIR tests reveal that HDP can selectively adsorb onto the surface of talc, with minimal adsorption on chalcopyrite. Further analysis through XPS and AFM indicates that HDP acts on the talc surface through physical adsorption, generating a larger phase angle to inhibit talc flotation. Concurrently, Density functional theory (DFT) simulation calculations suggest the presence of hydrogen bonding during the adsorption process between HDP and talc.

Adsorption mechanism of a biodegradable plant polyphenol depressant for selective separation of chalcopyrite from talc

In this paper, the effect of Tannic acid (TA), a green, biodegradable plant polyphenol, as a talc depressant on the separation behavior of talc and chalcopyrite was investigated. The results of micro-flotation studies revealed that at a TA dosage of 20 mg/L at pH 7, talc recovery was barely 10 % whereas chalcopyrite recovery remained above 90 %, indicating that TA can selectively depress talc flotation. The results of the artificial mixed minerals test further confirmed the depressive effect of TA. The adsorption results showed that the adsorption density of TA on talc was greater than that on chalcopyrite surface. Similar conclusions were observed in zeta potential tests. It is noteworthy that the zeta potential of the chalcopyrite treated with TA and butyl xanthate sodium continued to shift negatively in comparison to the zeta potential of chalcopyrite treated with TA alone, suggesting that butyl xanthate sodium can continue to adsorb on the surface of chalcopyrite following TA treatment. Besides, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy tests concluded that TA adsorbs on talc surface by physical (hydrophobic) interaction. Differences in the crystal structures of chalcopyrite and talc, as well as the large number of phenolic hydroxyl structures contained in TA, are the main driving forces for the selective adsorption of TA on the talc surface. This work provides an insight to the selection of inhibitors for the separation of chalcopyrite and talc, particularly from the perspective of the hydrophobic effect of the talc layered structure.

Enhanced inhibition of talc flotation using acidified sodium silicate and sodium carboxymethyl cellulose as the combined inhibitor

Enhanced inhibition of talc flotation using acidified sodium silicate and sodium carboxymethyl cellulose as the combined inhibitor

Depression mechanism of ZnSO4 and Na2CO3 on talc flotation

The depression mechanism of a combination of ZnSO4 and Na2CO3 on talc during chalcopyrite and molybdenite flotation was investigated in-depth using flotation tests, solution speciation calculations, and various characterization techniques. Flotation tests indicate that the effective depression of talc flotation occurred in the pH range of 7−9. In this pH range, speciation calculations for the mixed solution of ZnSO4 and Na2CO3 showed that the Zn5(OH)6(CO3)2 precipitate was the predominant zinc-bearing species, which was further proven by X-ray diffraction and infrared spectroscopy measurements. Zeta potential measurement highlighted that the Zn5(OH)6(CO3)2 precipitate was positively charged while the talc surface was negatively charged in the pH range where talc depression occurred. X-ray photoelectron spectroscopy and field emission scanning electron microscopy confirmed the presence of the zinc-bearing precipitate on the surface of the talc particles treated by the combination of ZnSO4 and Na2CO3. These findings suggested that heterocoagulation between the formed Zn5(OH)6(CO3)2 and talc occurred mainly due to the electrostatic attraction, thereby leading to the depression of talc flotation.

Application of exopolysaccharide directionally synthesized by Xanthomonas campestris as the green selective depressant for the clean flotation of talc: Statistical optimization and mechanism analysis

During froth flotation, the more non-polar, friable talc (Mg3(Si2O5)2(OH)2) usually adheres to the surface of sulfide ore and floats up, causing difficulties in flotation separation and subsequent industrial treatment. Microbial flotation as a green separation method avoids chemical contamination due to the limited selectivity and high agent consumption of the currently used inhibitors. Recent studies have found that exopolysaccharides produced by Xanthomonas campestris (X.c) could be used as inhibitors for the efficient flotation separation of talc from chalcopyrite. Therefore, this paper is the first attempt to optimize the molecular structure of exopolysaccharides and the optimal culture parameters of this strain to synthesize a green depressant for efficient flotation of talc, and also to explore in depth the mechanism of its selective inhibition of talc. Results of fermentation condition experiments and Fourier transform infrared analysis showed that the exopolysaccharides with the presence of polar groups (—OH and –COOH) significantly inhibited the floatability of talc. 1H Nuclear magnetic resonance further identified the active components of polar groups in the polysaccharide structure as hydroxyl groups, glucuronic acid, and pyruvic acid. Furthermore, the fermentation parameters were optimized by response surface methodology and increased the yield of exopolysaccharides by 5.55 g/L compared with before optimization. Flotation experiments on mixed ore confirmed the excellent selective inhibition of the synthesized exopolysaccharide at pH 7 and a 60 mg/L concentration. The contact angle test showed a significant decrease from 65.04° to 51.77° on the talc surface after the reaction with 60 mg/L concentration of exopolysaccharides. Atomic force microscopy characterization directly revealed the multilayer adsorption of exopolysaccharides on the talc surface, as well as a high coverage of 50.88%.

Insights into the adsorption performance and mechanism of hydrated Ca ion on talc (0 0 1) basal surface from DFT calculation

The utilization of Ca ion as assistant depressant of CMC on talc has been widely reported. Thus, the study on the adsorption mechanism of Ca ion on talc surface is very crucial for understanding the performance of CMC on talc depression. In this paper, mechanism insights into hydrated Ca ion adsorption on talc (0 0 1) basal surface were creatively provided using DFT calculation. [Ca(H 2 O) 6 ] 2+ and [Ca(OH)(H 2 O) 3 ] + were determined as the effective hydrate components for Ca ion adsorption, and the top O site was the most favorable position for their adsorptions on talc surface. Furthermore, the adsorption mechanisms of [Ca(H 2 O) 6 ] 2+ and [Ca(OH)(H 2 O) 3 ] + on talc surface were found to be not the Ca—O chemical bond, but the hydrogen bonding formed by the H atom of the H 2 O ligand and the surface O atom. H 2 O acted like a bridge to connect them to the talc surface. Moreover, the hydrogen bonding was formed due to the hybridization of H 1s orbital with the O 2s, O 2p orbitals. Simultaneously, electrons transferred between the H atom and the surface O atom. This work provides theoretical insights into the Ca ion adsorption on talc surface, which can help deeply understand the talc flotation using CMC as depression.

Effect of residual reagents on chalcopyrite losses at Mount Isa Mines copper operation: Part I – evaluation of mineral recoveries

Mount Isa Mines Copper Operation (MICO), owned by Glencore, is one of the largest copper producers in Australia. The concentrator has a complex circuit, which includes a pre-flotation section designed for early removal of deleterious talc, and other naturally floating gangue including carbonaceous material.The downside of early talc removal is the loss of chalcopyrite to the pre-flotation concentrate. This work investigates the role of residual collector and frother reagents on chalcopyrite losses in the MIM pre-flotation circuit, and the possibility of improving talc recovery whilst keeping chalcopyrite loss to a minimum. In Part I, the flotation response is evaluated as a function of mineral recoveries in order to differentiate talc flotation responses from those of other Methylglyoxal (MgO) containing minerals such as dolomite. This is achieved through the estimation of ore mineral content from elemental assays and a conversion methodology developed from historical mineralogy data.

Synergistic mechanism of acidified water glass and carboxymethyl cellulose in flotation of nickel sulfide ore

• The effect mechanisms of serpentine and talc on sulfide flotation are different. • Acidified water glass can eliminate heterocoagulation between serpentine and talc. • Carboxymethyl cellulose can inhibit talc flotation . • When serpentine and talc coexist, dispersants and inhibitors need to be used together. Efficiently utilizing nickel sulfide ores containing multiple magnesium silicate gangue minerals through flotation is difficult. Therefore, in this study, we investigated the flotation behavior and discussed the mechanism of a refractory nickel sulfide ore with multiple MgO gangue minerals. The synergistic mechanism of acidified water glass (AWG) and carboxymethyl cellulose (CMC) in the flotation of the nickel sulfide ore was studied through flotation tests, zeta potential measurements, adsorption capacity tests, Fourier transform infrared ray (FTIR) spectroscopy, and observation under a microscope. The results showed that the addition of AWG could change the electrical properties on the surface of serpentine, weaken the heterogeneous aggregation of serpentine and talc, and increase the selective adsorption of CMC on the talc surface. The actual ore flotation test was conducted with the synergistic effect of AWG and CMC. In the practical flotation test of the ore, the concentration of MgO in the concentrate, compared with the original process with CMC alone, was reduced from 9.62% to lesser than 5.92%, with the combined synergistic action of acidified sodium silicate and CMC acting as the depressant. Simultaneously, the grade and recovery of Ni from the Ni-mixed concentrate remained unchanged, and the inhibiting effect of the magnesium-bearing gangue minerals improved.

Mechanism insights into the hydrated Al ion adsorption on talc (001) basal surface: A DFT study

Al ion was reported to have an enhanced depression of Carboxymethyl cellulose (CMC) on talc flotation. However, how Al ion is adsorbed on talc surface remains unclear. Herein, the hydrated Al ion adsorption on talc (001) basal surface was creatively studied by DFT calculations. The effective number of H2O ligands in hydrated Al ion was probed and the optimal adsorption structure was investigated. We found that Al(OH)3(H2O) was the preferred hydrate structure, and the top O site was its optimal adsorption position on talc surface. Furthermore, Al-O chemical bond was not formed, and H2O was found to act as a bridge to connect the Al(OH)3(H2O) to talc surface by H-bond between H of H2O ligand and surface O instead of H-bond between H of Al(OH)3 in Al(OH)3(H2O) and surface O. However, [Al(OH)4]− cannot form the H2O bridge due to the electrostatic repulsion, and its adsorption on talc surface was energetically unsupportive. Moreover, we found that the formation of H-bond was due to the hybridization reaction between O 2p and H 1s orbitals, and slight electron transfers between O and H atoms were also observed. Finally, the Al(OH)3(H2O) was adsorbed on talc surface, which is consistent with the performed experimental result.

The flotation separation of molybdenite from talc using zinc sulfate in sodium silicate system and related mechanism

The function of sodium silicate is similar to that of sodium carbonate in flotation processes. In particular, in the presence of many different kinds of silicate gangue in minerals, sodium silicate performs better than sodium carbonate in inhibiting gangue formation by flotation. The results of this study showed that sodium silicate can replace sodium carbonate and inhibit talc flotation in combination with zinc sulfate; the associated depression mechanism was also investigated. The flotation results demonstrated that sodium silicate had a certain depressing effect on talc flotation compared with molybdenite, and that zinc sulfate could selectively inhibit talc flotation at pH ~10 in the sodium silicate system. Contact angle measurements further confirmed that the hydrophobicity of talc decreases upon the addition of zinc sulfate to the sodium silicate system. Fourier-transform infrared spectroscopy and zeta potential analysis provided strong evidence that zinc sulfate and sodium silicate underwent physical adsorption on talc surfaces. Additionally, zeta potential analysis, solution chemical analysis, and time-of-flight secondary ion mass spectrometry showed that sodium silicate may be hydrolyzed to form silicic acid micelles, which formed metal cation complexes with zinc sulfate and were intertwined and physically adsorbed on the talc surface.

Water Quality Change Due to the Mine Backfilling and Its Possible Response to Talc Flotation

A study was carried out in the framework of international R&D Project to determine the effect of water quality changes due to mine backfilling on talc flotation performance. The influence of two types of cemented paste backfill (Shotcrete and backfill) on flotation process water was investigated using the indoor soaking method, and the water quality was evaluated through water chemistry analysis, in addition to measuring pH, conductivity, and zeta potential as a function of soaking time. At the same time, talc batch flotation tests were performed using a KHD Humboldt Wedag lab cell for a period of 20 minutes. Soaking water at different soaking times was used as a process water for flotation, and tap water was also used to establish a reference response. Based upon the experimental results from the talc flotation and the several water quality parameters measured in the soaking water, conclusions were drawn.

How does the SDS addition in talc grinding affect its floatability?

Talc processing starts with grinding followed by flotation. The flotation feed preparation significantly affects the concentrate quality. In this study, the preparation of talc flotation feed by grinding was investigated in the absence and presence of sodium dodecyl sulfonate (SDS), one of the well-known flotation reagents. The natural floatability of talc was compared to its floatability after adding the SDS in either grinding or flotation. The results proved a significant effect of grinding conditions on its natural floatability. The higher flotation recovery is achieved by grinding at the alkaline medium compared to the acidic medium at 30% solids. More interestingly, adding the SDS in flotation produced a higher talc recovery than that the achieved recovery by its flotation after adding SDS in grinding although it has more chance for mixing the reagent with particles and adsorption of SDS to talc particles. Thus, the tested variables in grinding tests negatively affect the SDS effectiveness as a flotation reagent for talc.

Talc Flotation—An Overview

Talc is a naturally hydrophobic gangue mineral in most sulfide ores. However, talc has vast applications in the cosmetics, paper, and paint industries due to its high chemical stability, and its demand continues to grow. Since flotation is the most effective beneficiation technique for upgrading sulfides, the high hydrophobicity of talc has made its selective separation challenging. This paper explored the different properties of talc and the different factors that affect its flotation separation performance as a proven versatile beneficiation technique. Surface properties, zeta potential measurements, contact angles, and other factors affecting the talc flotation efficiency were discussed in detail. It was observed that the surface face/edge ratio (particle size) has a direct relationship with the level of talc hydrophobicity. Talc surfaces are negatively charged in a wide pH range (pH 2–12). Different depressants have already been studied; however, most of them showed low selectivity. The addition of ions such as Ca2+ could enhance talc depression. Pretreatment methods such as ultrasonic and thermal treatments were reported to decrease the talc floatability. It was demonstrated that the development of new selective depressants or pretreatment options for talc flotation requires attention in future investigations to improve its selective separation.

Effect of aluminum ions on the adsorption of carboxymethyl cellulose onto talc

Talc is a gangue mineral of many sulfide minerals, which is naturally hydrophobic. The depression of talc is very important and challenging in sulfide ore flotation. This research introduced aluminum ions into the process of using carboxymethyl cellulose (CMC) to depress talc. Flotation experiment results showed that aluminum ions used alone exerted a weak depression effect on talc, and that aluminum ions used in conjunction with CMC effectively depressed the flotation of talc at pH 8.5. Results of X-ray photoelectron spectroscopy and adsorption tests showed that the interaction of aluminum ions with talc changed the surface of talc, and Al(OH)3 formed on the talc surfaces, thereby promoting the adsorption of CMC onto talc and depressing the flotation of talc. On this basis, the morphology of CMC on the talc surface was observed by atomic force microscopy imaging. With the addition of aluminum ions, CMC aggregated to a greater extent, multiple layers adsorbed onto the surface of talc, and the coverage of CMC substantially increased. Based on all tests and analysis, the mechanism of the synergistic effect of CMC and aluminum ions on talc flotation was also proposed.

Flotation separation of molybdenite and talc by xanthan gum

In this study, the depressive effect of xanthan gum (XG) on molybdenite and talc flotation was studied using potassium butyl xanthate (PBX) as collector, and the mechanism through which molybdenite was separated from talc was investigated by Fourier transform infrared (FTIR) spectroscopy, Time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS). The single mineral flotation experiments showed that both molybdenite and talc were depressed by XG in the absence of PBX. When PBX was used, molybdenite recovered its excellent floatability while talc was still depressed by XG. In artificial mixed minerals flotation experiment, the flotation recovery of molybdenite remained around 80% while that of talc was about 20% at pH 3–9. XPS analysis results showed that XG adsorbed on molybdenite “surface” by physical adsorption instead of chemical adsorption and hydrophobic interaction played a main role. The results of FTIR spectroscopy and TOF-SIMS indicated that the pre-adsorption of XG on molybdenite cannot hinder the further chemisorption of PBX on molybdenite “edge”, leading to the co-adsorption of depressant and collector on molybdenite surface. Because PBX has no collecting ability on talc, the flotation separation of molybdenite and talc was achieved through the collecting of molybdenite by PBX and the inhibiting of XG on talc.

Study on the depression mechanism of zinc sulfate on talc in chalcopyrite flotation

Zinc sulfate is a commonly used selective depressant for zinc sulfide minerals, and a mixture of ZnSO4 and Na2CO3 is an effective combined inhibitor for talc. This study indicated that only using ZnSO4 could inhibit talc in chalcopyrite flotation and its depression mechanism was investigated. Microflotation tests indicated that ZnSO4 could selectively depress talc flotation when the pH was greater than about 7.5. Zeta-potential measurements indicated that ZnSO4 could change the zeta-potentials of talc but had a slight influence on that of chalcopyrite. Solution chemistry study of ZnSO4 solution indicated that when the pH was greater than about 7, the hydrophilic precipitate of zinc hydroxide generated. Fourier transform infrared spectra (FTIR) measurements and X-ray photoelectron spectroscopy (XPS) analysis indicated that the precipitate of zinc hydroxide could adsorb on talc surfaces, and Mg2+ ions of talc surfaces may be the active sites which interacted with the precipitate. These results demonstrated that the precipitate of zinc hydroxide was the species of ZnSO4 solution which inhibited talc flotation. The adsorption morphology of the precipitate on talc surfaces was observed by AFM, suggesting that the adsorption of the precipitate roughened the talc surfaces.

The effect of lizardite on talc flotation using carboxymethyl cellulose as a depressant

The effect of lizardite on talc flotation using carboxymethyl cellulose as a depressant