Depression Of Pyrite Research Articles

Effect of sodium metabisulfite and slaked lime on the floatability and surface properties of chalcopyrite

In the flotation of complex copper ores containing chalcopyrite in seawater, sodium metabisulfite (SMBS) has been widely used as a pyrite depressant. Here, calcium ions in seawater or in process water because of pH control using lime (CaO) or slaked lime (Ca(OH) 2 ) can affect the floatability of chalcopyrite. However, the effect of SMBS on the floatability of chalcopyrite in the presence of calcium ions is unknown. Therefore, the current study investigated the flotation behavior and surface properties of chalcopyrite after treatment with SMBS in the absence and presence of Ca(OH) 2 . The flotation experiments demonstrated that both SMBS treatment and the addition of Ca(OH) 2 exhibited a depressing effect on the natural floatability of chalcopyrite. This depressing effect of SMBS and Ca(OH) 2 on the floatability of chalcopyrite was significantly decreased in the presence of potassium amyl xanthate (PAX). However, the combination of SMBS treatment and Ca(OH) 2 formed calcium sulfite (CaSO 3 ) on the surface of chalcopyrite, which significantly reduced the recovery of chalcopyrite from 97% to 66% when in the presence of PAX and at a pH of 9. • The effect of Na 2 S 2 O 5 (SMBS) and Ca(OH) 2 on the floatability of chalcopyrite was studied. • Both SMBS and Ca(OH) 2 exhibited a depressing effect on the recovery of chalcopyrite. • SMBS produced sulfate and hydrophilic species on the surface of chalcopyrite. • SMBS and Ca(OH) 2 form CaSO 3 precipitate that reduced the recovery of chalcopyrite. • SMBS reduced the adsorbed PAX on the surface of chalcopyrite.

Application and depression mechanism of sodium sulfite on galena-pyrite mixed concentrate flotation separation: Huize Lead-Zinc Mine, China, as an example

Galena, sphalerite, and pyrite are important metallic sulfide minerals and are often associated with one another. In the flotation separation of galena-pyrite mixed concentrate, large amounts of lime (CaO) are used for the depression of pyrite. In this study, the negative effects of lime were reduced by using an efficient depressant Na2SO3 + CaO reagent in the flotation separation of galena from pyrite. Real ore sample flotation separation tests showed that the mixed depressant can efficiently depress pyrite from galena-pyrite mixed concentrate. The obtained galena concentrate had a Pb recovery and grade of 58.36% and 83.45%, respectively. Micro-flotation experiments showed that Na2SO3 depressed the floatability of pyrite more strongly than that of galena. Moreover, the depression mechanism of Na2SO3 was observed through contact angle measurements, ultraviolet–visible spectrophotometry (UV–Vis) analysis, and time of flight secondary ion mass spectrometry (TOF-SIMS). This study provides an important reference for the depression of pyrite from a galena-pyrite mixed concentrate with low lime dosage.

The selective depression effect of dextrin on pyrite during the Zn–Fe sulfides flotation under low alkaline conditions

As an environmentally friendly scale inhibitor, characterized by low cost, high efficiency and no secondary pollution, dextrin was utilized as a depressant in the flotation separation of mixed Zn-S concentrate. The microflotation results clearly demonstrate that dextrin exerted a good inhibitory effect on pyrite and sphalerite could be separated successfully from pyrite in low alkaline environment. The mixed mineral flotation results further indicate that sphalerite could be efficiently separated from its synthetic mixture with pyrite via the use of dextrin as the depressant in the pH range of 7–9. The contact Angle test shows that dextrin can be adsorbed on the surface of Cu-activated pyrite to enhance hydrophobicity, but not on the surface of Cu-activated sphalerite. The results of infrared spectroscopy investigations and XPS analyses indicate that under low alkali conditions, copper ions activate sphalerite, and copper sulfide polysulfide forms on sphalerite surface without Cu(OH)2 formation. Cu(OH)2, Fe(OH)2 and CuS were generated on pyrite surface due to the activation of copper ions. The adsorption between dextrin and metal hydroxyl compounds was the main cause of pyrite inhibition， which is attributed to the hydrophilic hydroxyl group in the dextrin molecule. According to these results, dextrin can be used as a selective depressant for pyrite during sphalerite flotation in low alkaline environment.

Selective separation of chalcopyrite and pyrite using a novel organic depressant at low alkalinity

The selective depression effect and mechanism of the organic depressant sodium dimethyl dithiocarbamate (SDD) on pyrite in the flotation system of chalcopyrite and pyrite at low alkalinity (pH 8.5) were investigated. The results of single mineral microflotation tests indicated that the recovery efficiency of pyrite decreased from 80.23% to 39.18% after SDD was added, while the recovery efficiency of chalcopyrite decreased from 97.74% to 93.07%. This indicates that SDD has a clear selective depression effect on pyrite, but it has little depression effect on chalcopyrite. X-ray photoelectron spectroscopy (XPS) showed that at low alkalinity (pH 8.5), SDD chemical adsorbed on the surface of pyrite to form water-insoluble complexes, the flotability of pyrite surface was decreased. However, adsorption of SDD on the surface of chalcopyrite was weaker than that on pyrite, which increases the flotability difference between the two surfaces and leads to selective depression of pyrite.

Kinetic Investigation of Initial Oxidative Dissolution of Pyrite in Alkaline Media (pH 9–12) and Influence of Ca and Mg: A Fundamental Study for Pyrite Depression in Froth Flotation

Kinetic Investigation of Initial Oxidative Dissolution of Pyrite in Alkaline Media (pH 9–12) and Influence of Ca and Mg: A Fundamental Study for Pyrite Depression in Froth Flotation

Oxidation-reduction effects in the flotation of copper sulfide minerals and molybdenite – A proof of concept at industrial scale

Redox potential (Eh) control plays a significant role during sulfide mineral flotation by influencing the reactions on the surface of the minerals and accordingly the flotation behaviour. In this study, the metallurgical performance of typical copper sulfide minerals, molybdenite as well as gangue minerals (e.g., pyrite, tennantite, and enargite) under different pH and Eh conditions of the flotation cell were investigated. The copper and molybdenum processing plant at the Sungun complex-Iran were selected as a case study. For this purpose, Eh of flotation cells of phases 1 and 2 of copper and molybdenum processing circuits – Sungun complex – were measured by off-line method. After performing chemical analysis, the mineralogical study of the input load and products of each of the aforementioned flotation circuits in the rougher, cleaner, re-cleaner, and scavenger stages was performed. Based on the results, the potential in cells of phases 1 and 2 of copper concentration plants is in the range of −60 to −100 mV; and for the molybdenum plant, is in the range of −500 to −700 mV. The potentials of more than −100 mV in the phases of copper concentration plants have created suitable conditions for the separation of copper sulfide and molybdenite minerals from gangue minerals, especially pyrite. Adjustment of Eh in the range of −500 to −700 mV in the molybdenum processing plant has also led to the depression of copper minerals and the flotation of molybdenite, resulting in the effective separation of these minerals. However, grade analysis and mineralogical studies indicate the misplaced copper minerals into tailings, the passage of chalcopyrite and pyrite to molybdenum concentrate, the misplaced molybdenite to copper concentrate, and also the presence of minerals containing harmful elements such as arsenic in copper concentrate. Eh fluctuations in phase 1 and 2 of copper plants, the interaction of copper sulfide minerals, especially chalcopyrite with pyrite (and the depression of pyrite in Eh more than −100 mV), are reasons for the misplaced copper minerals into tailings. The interaction of chalcopyrite and pyrite with molybdenite and the high flotation tendency of molybdenite at the potential of +600 mV is the main factor in increasing the Cu and Fe grade in molybdenite concentrate. The interaction of copper minerals with arsenic-bearing minerals and the similar flotation behavior of these minerals in the potential of the rougher cells of the molybdenum processing plant has increased the arsenic grade in the copper concentrate or molybdenum tailings.

Enhanced separation of base metal sulfides in flotation systems using Chitosan-grafted-Polyacrylamides

• Chitosan-grafted-Polyacrylamide (Chi-g-PAM) was prepared and characterized. • Adsorption studies of Chi-g-PAM on metal sulfide surfaces were conducted. • Chi-g-PAM was tested as pyrite’s depressant in metal sulfide flotation. • Chi-g-PAM outperformed other depressants at producing less pyrite-diluted products. In this study, chitosan-grafted-polyacrylamide (Chi-g-PAM), a synthetic biocompatible polymer was investigated as a selective depressant of iron sulfide minerals [i.e., pyrite (FeS 2 )] in the flotation process of base metal sulfide minerals [i.e., galena (PbS), chalcopyrite (CuFeS 2 ), and sphalerite (ZnS)]. Chi-g-PAM was successfully synthesized by grafting polyacrylamide chains onto chitosan backbone. The synthesized polymer was characterized using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), and X-ray Powder Diffraction (XRD) analysis. Adsorption studies of Chi-g-PAM on mineral surfaces were conducted using zeta potential, contact angle, and total organic carbon (TOC) measurements in addition to X-ray Photoelectron Spectroscopy (XPS). Adsorption tests showed that Chi-g-PAM was most selective to pyrite as compared to the base metal sulfides indicating that this polymer may have the potential to be used as pyrite’s depressant in the flotation of base metal sulfides under specific conditions. XPS studies suggested that the depression of pyrite by Chi-g-PAM was due to chemisorption of the amine, amide, and hydroxyl groups of Chi-g-PAM at pyrite-water interface. The impact of Chi-g-PAM on the flotation response of sulfide minerals was investigated in both microflotation and batch flotation systems using model minerals and real sulfide ore, respectively. In microflotation tests of model minerals, the best separation efficiencies between valuable base metal sulfides and pyrite were achieved at pH 7. In batch flotation tests of complex sulfide ore of Mississippi Valley type (MVT) at natural pH (7.8), a separation efficiency of 61% was achieved between galena and pyrite when Chi-g-PAM was used compared to 35% with sodium cyanide (NaCN), the depressant that is commonly applied for this type of ore. However, the separation efficiency between chalcopyrite and pyrite was 15% and 21% with Chi-g-PAM and NaCN, respectively. Comparative studies indicated that Chi-g-PAM outperformed other depressants at producing less pyrite-diluted flotation concentrates.

Separation mechanism of chalcopyrite and pyrite due to H2O2 treatment in low-alkaline seawater flotation system

The effects of H2O2 on the flotation separation of chalcopyrite and pyrite in seawater were investigated. Pyrite was more significantly oxidized by 0.05 vol% H2O2 in seawater at pH 8, as compared to that of chalcopyrite. Under optimized condition, a recovery difference of greater than 70% was obtained for chalcopyrite and pyrite. The contact angle measurements showed that pyrite surface was more hydrophilic as compared to chalcopyrite in the presence of 0.05 vol% H2O2. In addition, the collector of butyl xanthate is more difficult to adsorb on the surface of H2O2-treated pyrite (adsorption dosage reduced from 0.18 to 0.06 mg g−1), further decreasing its floatability. The heat released due to xanthate adsorption on chalcopyrite and pyrite decreased from 26.5 mJ to 25.9 mJ and from 23.1 mJ to 15.2 mJ, after H2O2 treatment, respectively, indicating less adsorption of xanthate due to the oxidation treatment, especially for pyrite. The XPS data indicated the dissolution of Fe from the oxidized chalcopyrite surface and the formation of various hydrophobic S species such as S22-, Sn2-, S0 on chalcopyrite surface. In contrast, Fe(II) on pyrite surface was oxidized by H2O2 to form hydrophilic Fe2O3, Fe(OH)3, FeOOH and Fe2(SO4)3 species. Therefore, this study reveals that H2O2 can be used as a high-efficient depressant for pyrite when separating chalcopyrite and pyrite in low-alkali seawater flotation system.

Effects of Pyrite Texture on Flotation Performance of Copper Sulfide Ores

Pyrite particles, having framboidal/altered texture, are known to significantly affect pulp chemistry and adversely affect flotation performance. Therefore, the main objectives of this study were to demonstrate influence of pyrite mineralogy on the flotation of copper (sulphidic) ores and develop alternative conditions to improve the performance. Two copper ore samples (Ore A and Ore B) having different textural/modal mineralogy and flotation characteristics were taken from different zones of the same ore deposit. Ore B contained framboidal pyrite and altered pyrite/marcasite, which is considered the main reason for the low flotation performance in both copper and pyrite flotation sections of the process plant. Flotation tests were conducted under different conditions using the two ore samples and a 50:50 blend. The results showed that Ore A could be concentrated under the base conditions, as applied in the existing flotation plant. On the other hand, Ore B did not respond to the base conditions and a copper recovery of only 5% could be obtained. Besides, blending Ore B with Ore A negatively affected the flotation behavior of Ore A. An alternative flotation chemistry was applied on Ore B using Na2S for surface cleaning and Na-Metabisulfite (MBS) for pyrite depression in the copper flotation stage. The surface cleaning reduced the rate of oxidation of the framboidal pyrite in Ore B. As a result, the copper recovery could be increased to 52% Cu for Ore B, and 65% for the mixed ore sample.

Flotation behavior of native gold and gold-bearing sulfide minerals in a polymetallic gold ore

In this study, the flotation behaviors of gold and gold-associated sulfide minerals (pyrite and sphalerite) in a polymetallic sulfide gold ore were investigated using flotation kinetics parameters. It was found that high gold recovery (>90%) can be achieved by the selective flotation of pyrite and sphalerite. However, the sphalerite flotation results showed that sphalerite could not be separated from pyrite with a high selectivity (selectivity index∼1), because of insufficient depression of pyrite (with high alkaline medium and/or using a depressant). Even if more selective separation was achieved from the pyrite flotation (selectivity index∼5), 40% of sphalerite in the ore was transferred into the pyrite concentrate. In addition, the results of the collectorless tests indicated that more than 80% of the gold can be recovered, and higher selectivity indexes (up to 10) are achievable. Analysis of the particle size distribution of the collectorless flotation concentrate showed that the amount of −40 μm in the concentrate was 90%. In conclusion, a gold concentrate containing low sulfur (10.8%) with a gold recovery of greater than 95% is achievable from a two-stage flow sheet (collectorless flotation as the rougher stage and pyrite flotation as the scavenger stage).

On the use of Na<sub>2</sub>SO<sub>3</sub> as a pyrite depressant in saline systems and the presence of kaolinite

On the use of Na<sub>2</sub>SO<sub>3</sub> as a pyrite depressant in saline systems and the presence of kaolinite

Adsorption mechanism of a new depressant on pyrite surfaces and its application to the selective separation of chalcopyrite from pyrite

Selecting a suitable depressant that strongly depresses the pyrite flotation but has little effect on the floatability of chalcopyrite is of great significance for selectively separate chalcopyrite from pyrite. In this study, galactomannan (GM) was used to replace traditional depressants for depression of pyrite. The depression performance and adsorption mechanism of it on the pyrite surface were investigated by micro-flotation tests, zeta potential measurements, Fourier transform infrared spectroscopy (FTIR) measurements, and X-ray photoelectron spectroscopy (XPS) analyses. The results showed that, compared with guar gum, polyacrylamide (PAM), dextrin, carboxymethylcellulose (CMC), sodium hexametaphosphate (SHMP), GM had the optimum depression effect on pyrite, but had a negligible effect on chalcopyrite. A satisfactory separation of chalcopyrite and pyrite was achieved at weakly alkaline condition (pH 8), at which the flotation recovery of chalcopyrite was 86.11% and that of pyrite was only 13.85%. The results of surface analyses confirmed that GM could be selectively chemisorbed on pyrite surface through the Fe sites and impede the further adsorption of sodium butyl xanthate (SBX). The use of GM as a depressant, therefore, enabled the effective separation of chalcopyrite from pyrite.

Recovery of high-grade copper concentrate from sulfur-rich porphyry ore using tricarboxystarch micromolecule as pyrite depressant

Tricarboxystarch (sodium salt), also known as TCSS, has been studied as a selective depressant of pyrite in chalcopyrite flotation using xanthate as a collector. In microflotation, tricarboxystarch achieved strong and selective depression of pyrite flotation than chalcopyrite under weakly acidic conditions. In this study, the performance of tricarboxystarch as a pyrite depressant was further investigated by using it in batch flotation experiments on sulfur-rich copper sulfide ore. The effects of the addition of tricarboxystarch on improving Cu grade and reducing S grade were investigated at different pH of solution and different doses of reagent. The overall batch experiment consisted of bulk roughing and cleaning flotation, followed by the removal of pyrite with the addition of depressant. Using tricarboxystarch as a depressant, a new environmentally friendly closed-circuit beneficiation process for a sulfur-rich copper ore was also designed in this work. The results of batch flotation experiments show that the addition of a low dose of tricarboxystarch under weakly acidic conditions (pH 6) yields a very high grade copper concentrate containing approximately 21.85% Cu and 33.78% S. As an inexpensive and eco-friendly polymer, tricarboxystarch usage may significantly reduce the reagent cost and potential environmental impact in the mineral industry.

Pyrogallic acid as depressant for flotation separation of pyrite from chalcopyrite under low-alkalinity conditions

Effective and low-cost flotation separation of chalcopyrite and pyrite has always been a challenge in the minerals processing industry. Traditional depressants in a Cu–Fe sulfide flotation system, such as lime, tend to require a high dosage and have low selectivity. We investigated the effect of pyrogallic acid on the flotation separation of chalcopyrite and pyrite. After treatment with pyrogallic acid under appropriate conditions, pyrite recovery dropped by 65%, while that of chalcopyrite dropped only slightly. Adsorption measurements showed that pyrogallic acid significantly reduced the amount of sodium butyl xanthate adsorption on the pyrite surface. Zeta potential, infrared, and X-ray photoelectron spectroscopy analyses confirmed that pyrogallic acid most likely interacts with pyrite surface via chemisorption with Fe sites, and thereby strengthens the hydrophilicity of the pyrite particles. Localized electrochemical impedance spectroscopy measurements further indicated that pyrogallic acid could significantly adsorb on the pyrite surface. Therefore, Pyrogallic acid could be a promising depressant for pyrite and provide flotation separation of Cu–Fe sulfide ores under low-alkalinity conditions.

Selectively Depress Copper-Activated Pyrite in Copper Flotation at Slightly Alkaline pH

Pyrite depression in the flotation of copper ores is difficult due to the activation of Cu2+ ions on pyrite surface. In this study, the radical chain reaction involving the redox cycling of Cu(I/II) induced by sodium metabisulphite (MBS) was exploited to selectively depress the flotation of copper-activated pyrite at pH 8.0. Electrochemical measurements revealed that the presence of Cu2+ and O2 was essential to the formation of $$ {\mathrm{SO}}_5^{\bullet -} $$ through sulphite oxidation, the main entity to convert the activating species Cu(I)S on pyrite to Cu(II)-hydroxide/sulphate, causing deactivation of pyrite. The depression role of MBS on pyrite flotation was closely associated with the type of grinding media which affected the electrochemical conditions of flotation. When forged steel was used as the grinding media, a high dosage of MBS was required to depress pyrite, but a low dosage of MBS could almost completely depressed pyrite when high chrome steel grinding media was used. This is because high chrome steel produced a stronger oxidation condition with a higher amount of Cu2+ and O2 which promoted the formation of $$ {\mathrm{SO}}_5^{\bullet -} $$ .

The synergistic depression of lime and sodium humate on the flotation separation of sphalerite from pyrite

Pyrite depression in flotation separation of Zn-S mixed concentrate has become a difficult and serious problem. This work introduces a non-toxic and efficient depressant reagent scheme in selective flotation separation of spalerite from pyrite with pretreatment by CuSO4 and butyl xanthate (BX). Micro-flotation experiments showed that the combined depressant lime (CaO) and sodium humate (NaHA) depressed the floatability of pyrite more strongly than that of the sphalerite within at pH 11.5–12.0. Moreover, the inhibitory effect of NaHA on pyrite was significantly promoted by calcium-species dissolved from CaO. Real ore sample flotation separation tests showed that the mixed depressant CaO and NaHA acted better than single depressant CaO or NaHA, and the best results were obtained by addition of 850 g/t CaO and 30 g/t NaHA at pH 11.5, with 46.01% Zn grade and 90.11% Zn operating recovery. The synergistic depressing mechanism of CaO and NaHA was revealed through adsorption amount measurements, contact angle measurements, fourier infrared spectroscopic (FT-IR) analysis and X-ray photoelectron spectroscopy (XPS) analysis. Mechanism experiments indicated that the addition of calcium species (mainly as Ca2+ and Ca(OH)+) promoted the adsorption of NaHA on mineral surfaces, and the pyrite surface adsorbed much more calcium-species and NaHA than that of the sphalerite. The chemical adsorption of NaHA on pyrite was mainly through its carboxyl groups and Ca atoms on pyrite surface, while the NaHA adsorption on sphalerite surface was relatively weak.

Evaluation of green synthetic depressants for sulfide flotation: Synthesis, characterization and floatation performance to pyrite and chalcopyrite

Native starch has a complex molecular structure that limits its ability as a selective depressant in sulfide flotation separations. This research study was conducted primarily to develop a series of starch-based molecules of different molecular weights with the aim of obtaining the most selective depressant of pyrite in chalcopyrite flotation. Five low molecular weight molecules were produced by the oxidative treatment of starch using H2O2 as the oxidant and FeSO4·7H2O as the catalyst. Oxidation treatment resulted in molecular modification of starch, producing low molecular weight molecules of grafted polar groups with increased reaction time. The molecules developed were investigated by microflotation to obtain the most selective and effective depressant for pyrite than chalcopyrite. The optimal and most selective depressant was named tricarboxystarch (sodium salt), also known as TCSS, based on the results of characterization measurements. The inhibitory effect of tricarboxystarch on pyrite was far more selective and effective than native starch. Good selective separation between pyrite and chalcopyrite was achieved by adding tricarboxystarch to a low pH solution. Tricarboxystarch contained three –COOH and several –OH groups in the skeleton, providing excellent depression of pyrite. This study is a basic research that sheds new light on the development and optimization of organic polymers for flotation technology.

A comparison of native starch, oxidized starch and CMC as copper-activated pyrite depressants

The performance of native wheat starch (NWS), a hydrogen peroxide-oxidized wheat starch (Perox 3/30) and carboxymethyl cellulose (CMC) as copper-activated pyrite depressants are compared in lab-scale flotation trials. Both Perox 3/30 and CMC demonstrate similar and significantly better performance than NWS at dosages 100–300 g/t. At 700 g/t, both starches depressed essentially all of the copper-activated pyrite, whereas there was little change in recovery for CMC dosages above 300 g/t. The improved performance of Perox 3/30 and CMC at lower dosages appears to be associated with the presence of polymer structures with a hydrodynamic radius, Rh, of approximately 12–15 nm that are able to form a layer on the pyrite surface that is effective in preventing collector interaction. The continual decrease of flotation recovery with increasing NWS and Perox 3/30 dosage is likely associated with the greater molecular size of the starch polymers in that more hydroxyls can be associated with each adsorption site. The presence of branches on the starches that can extend from the pyrite surface plane may also improve interaction with the water phase near the surface, increase hydrophilicity and hence improve depression. Overall, the conformation of supramolecular and molecular structures of the polymers investigated here appear to be more influential than functional groups for depressing copper-activated pyrite.

Influence of indigenous mixotrophic bacteria on pyrite surface chemistry: Implications for bioflotation

Given the low-cost and eco-friendly method, biotechnology has been widely utilized in industries as an alternative for physical and chemical processes, including in the biomining process (e.g., bioflotation and biobeneficiation). However, the use of biochemical reagent, which is selective for certain minerals, has not been well studied. This research was aimed to investigate the potential use of biosurfactant-producing mixotrophic bacteria as an alternative to chemical reagents during bioflotation and biobeneficiation process. Thirteen bacterial strains were investigated for their ability to produce biosurfactants and their effects on the surface properties of pyrite minerals. Bacteria-pyrite interaction experimental results showed that pyrite surface properties became more hydrophilic in the experimental systems inoculated with bacteria adapted with pyrite for 48 h than that without bacterial adaptation to pyrite, which was evidenced by the decrease in the contact angle of pyrite minerals by up to 50%. This evidence was also confirmed by the highest emulsifying index value (51.6%) attained during the bacteria-pyrite interaction. Hence, these bacteria can potentially be applied to selective flotation as pyrite depressants.

Interaction mechanism of tannic acid with pyrite surfaces and its response to flotation separation of chalcopyrite from pyrite in a low-alkaline medium

In the process of chalcopyrite–pyrite flotation, depression of pyrite is of great significance. In this study, tannic acid (TA) was used to replace traditional inorganic reagents for depression of pyrite under the low-alkalinity condition, and the interaction mechanism of TA with the pyrite surface was studied. Adsorption experiments showed that adsorption of xanthate on the pyrite surfaces was greatly inhibited after treatment with TA, while that of chalcopyrite was only slightly affected. Zeta potential measurements suggested that TA decreased the surface potential of pyrite among pH 3–10. A new characteristic peak appeared in the pyrite–TA infrared spectrum. Time-of-flight secondary-ion mass spectrometry and X-ray photoelectron spectroscopy measurements revealed that Fe atoms were the active sites on the pyrite surface, and they strongly interacted with TA. Microflotation tests confirmed that TA had an obvious depression effect on pyrite, but it had no distinct depression effect on chalcopyrite. These results verified that TA can selectively weaken the floatability of pyrite in Cu–Fe flotation, thereby enabling separation of chalcopyrite from pyrite at low alkalinity.