Depression Of Pyrite Research Articles

Effect of D-arginine as a novel depressant on the flotation separation of chalcopyrite from pyrite at low alkalinity

Flotation separation of Cu–Fe sulfide minerals typically necessitate the addition of substantial quantities of lime to depress pyrite flotation. Because lime can harm the environment, there is an urgent need to develop novel environmentally friendly depressants that are non-toxic and biodegradable. In this study, we investigated an environmentally friendly pyrite depressant containing amino and carboxyl groups, namely D-arginine (DA). The effect of DA on the surface hydrophobicity of Cu–Fe sulfide minerals and thus collector adsorption was investigated by analyzing zeta potentials, adsorption capacities, and contact angles. Additionally, changes in the surface properties of the minerals induced by DA were examined using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and atomic force microscopy (AFM). Flotation tests revealed that 2 × 10–4 mol/L DA reduced the flotation recovery of pyrite to 9.96 % at low alkalinity while leaving chalcopyrite recovery unchanged. The results of mineral surface analysis indicated that DA exhibited significantly stronger adsorption on the pyrite surface than on the chalcopyrite surface. Furthermore, DA effectively reduced the adsorption of the collector on the surface of pyrite, thereby weakening pyrite floatability at low alkalinity. Therefore, DA is a promising alternative depressant for the flotation separation of chalcopyrite from pyrite.

Pyrite Depression by Sodium Metabisulfite in Freshwater and Seawater with Copper Activation

Pyrite has natural floatability and thus readily enters valuable mineral flotation concentrates, diluting their quality and decreasing their economic value. Its separation is challenging, depending on process conditions, the presence of activating ions, and water quality, particularly in regions where seawater is used. This study examines the effect of various doses of sodium metabisulfite (SMBS) on pyrite depression in freshwater and seawater under weakly alkaline conditions and with different copper ion concentrations. Without the addition of activators or depressants, pyrite recovery is 40% in freshwater and 60% in seawater, whereas with 10 ppm of SMBS, recoveries drop to 28% and 38%, respectively. The addition of 10 ppm Cu2+ increases recovery by 10% in freshwater and by 20% in seawater. In the presence of 75 ppm of PAX, maximum recovery reached 50% in freshwater and 80% in seawater. These results suggest that cationic bridges formed by seawater ions, combined with CaOH+ activation, play a critical role in pyrite activation, even in the presence of depressants.

Mechanism of pyrite depression by marine Fe(II)-oxidizing bacteria in seawater flotation

Seawater flotation is a promising technique to reduce environmental and economic loads in mineral processing. This study attempted to depress pyrite, a common gangue sulfide mineral, using two marine iron (Fe) oxidizing bacteria (MFeOB), Thalassospira sp. TF-1 and Mariprofundus sp. E-4, in seawater flotation without pH control; the MFeOB could contribute to hydrophilization of the pyrite surface by oxidation and/or adhesion of bacterial cells. Pyrite or chalcopyrite samples were preconditioned in seawater containing MFeOB for different times (15 min or 30 min). As a result of flotation experiments, the recovery of pyrite preconditioned without MFeOB (i.e., control sample) decreased to 64.2 % after 30 min reaction. The same recovery was observed when pyrite was preconditioned with Thalassospira sp. TF-1, whereas the recovery was successfully decreased to 20.2 % after preconditioning with Mariprofundus sp. E-4 for 30 min. X-ray photoelectron spectroscopy analysis of preconditioned pyrite samples showed no significant difference of Fe-oxidizing compounds between with and without MFeOB reaction, suggesting that the formation of hydrophilic substances such as Fe(OH)3 derived from pyrite oxidation by MFeOB is unlikely to be the main reason for the pyrite depression by Mariprofundus sp. E-4. The adhesion experiment revealed that MFeOB cells could cover the pyrite surface but not the chalcopyrite surface, showing that the hydrophilicity of Mariprofundus sp. E-4 cell caused the pyrite depression. This result suggests that the hydrophilic/hydrophobic properties of bacterial cells are a significant determining factor in pyrite recovery in seawater flotation in the case of MFeOB.

Separation of galena and pyrite via green organic macromolecules at low alkalinity: Flotation response and surface adsorption mechanisms

Pyrite must be separated from galena during the beneficiation stage because it releases toxic gases during pyrometallurgy. However, the separation of the two minerals presents a huge obstacle as they have comparable hydrophobicity. This work offers an environmentally friendly pyrite depressant, pullulan polysaccharide (PP), for concentrating galena. Single mineral flotation showed that the ability of PP to deteriorate floatability was significantly stronger for pyrite than for galena within the pH range of 6.00 − 12.00. PP preadsorption assisted in separating galena from pyrite in a low-alkalinity pulp. The recovery of galena was 71.20 % higher than that of pyrite in the binary mineral flotation system. Characterization results confirmed that the Fe sites of pyrite were more susceptible to forming a stable coordination with the O atoms of PP’s C−O−H group compared to the Pb sites of galena. PP can impede the sodium butyl xanthate (BX) sorption on the pyrite surface, thus effectively depressing the pyrite. By contrast, the sorption of BX onto the galena surface was unaffected by PP, and the galena remained floatable. Thus, PP could be considered as an alternative to conventional inorganic depressants in the galena–pyrite flotation system. This work provides a scientific reference for the green and sustainable exploitation of non-ferrous metal resources.

Impact of Pyrite Textures Prevalence on Flotation Performance in Mount Isa Copper Orebodies

ABSTRACT Pyrite, the most abundant sulfide mineral in base-metal deposits, presents significant challenges in mineral processing due to its deleterious effects when not properly managed. Its undesirable association with valuable minerals leads to low-quality concentrates, hindering smelting processes. Pyrite’s distinct textures and variable elemental compositions affect its floatability, with complex textures challenging to depress. Moreover, since multiple textures can be present within an orebody, their relative proportion in the ore could affect the overall flotation performance. Therefore, understanding the types of pyrite present, their abundance, and how they affect the flotation behavior of the ore is critical for an efficient depression and possible reclamation of pyrite. At the Mount Isa copper deposit, framboidal or ‘carbonaceous’ pyrite has been an ongoing challenge to the copper concentration operation, reducing the flotation circuit’s efficiency. Previous work by Yenial-Arslan et al. showed that high pyrite recoveries could be strongly linked to the prevalence of fine-grained pyrite. However, samples belonging to the coarse pyrite domain exhibited low natural floatability. This study further investigates the effect of the prevalence of pyrite textures on the flotation performance of copper orebodies at the Mount Isa deposit. The prevalence of pyrite textures was quantified and statistically linked to the natural floatability of pyrite, proving that fine-grained and framboidal pyrite greatly influence pyrite’s overall recovery. Furthermore, various mineral characterization techniques, such as synchrotron X-ray fluorescence microscopy (XFM) analysis, were used to explore how the natural floatability of pyrite was affected.

Activation flotation of lime-depressed pyrite with carbon dioxide: Performances, mechanism and pilot-scale application

Activation flotation of lime-depressed pyrite by sulfuric acid (H2SO4) is usually accompanied by safety hazards and environmental pollution. Exploring eco-friendly, economical and effective activator to replace H2SO4 holds great significance for the sustainable development of mining industry. In this study, carbon dioxide (CO2) as a potential activator was applied in activation flotation of lime-depressed pyrite. Micro-flotation experiments results showed CO2 significantly improved the floatability of pyrite, and a maximum recovery of 93.94% was achieved under optimal operating conditions. The activation mechanism was investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Results indicated the depression of pyrite by lime was attributed to the formation of iron oxide/hydroxide species and calcium film, and CO2 effectively eliminated these hydrophilic compounds from the surface of pyrite, thus promoted the adsorption of xanthate onto the pyrite surface. Moreover, the anodic oxidation of xanthate on pyrite and the influence of CO2 on this process were investigated by cyclic voltammetry measurements. It was found that xanthate oxidation to form dixanthogen was more likely to occur in the presence of CO2, and this reaction replaced pyrite surface oxidation as the dominant anodic process. Finally, pilot-scale experiments were successfully conducted and the recovery of pyrite reached 93.18%, surpassing the ore dressing index of using H2SO4 as activator in actual production at the same period. Moreover, the concentration of sulfate ions in mineral processing wastewater was significantly reduced, and the annual cost of activator can be saved by 0.52 million RMB. The new process of activation flotation pyrite with CO2 has prospects for large-scale application in terms of activation performance, cost-effectiveness and environmental impact.

Application and depression mechanism of sodium humate on flotation separation of molybdenite and pyrite

ABSTRACT The depression of pyrite in the flotation separation of molybdenum-sulfur (Mo-S) mixed concentrate has become a significant issue. This study aimed to examine the process of separating molybdenite and pyrite in the presence of sodium humate (NaHA). The results of micro-flotation tests indicated that NaHA exhibited significant pyrite depression capabilities and displayed remarkable selectivity toward both pyrite and molybdenite. Real ore flotation experiments have shown that adding 22.5 mg/L of NaHA to the pulp of Mo-S mixed concentrate at a pH of 6.5, the flotation indexes achieved 46.01% Mo grade and 90.11% Mo recovery. It is noteworthy that the dosage of NaHA was significantly lower compared to the 505 utilized in the mineral processing plant. Contact angle measurements revealed that NaHA effectively increased the surface hydrophilicity of pyrite. Adsorption amount measurements, zeta potential measurements, and Fourier infrared spectroscopic (FT-IR) analysis indicated that the adsorption capacity of NaHA on pyrite was higher than on molybdenite. NaHA had a highly selective inhibitory capacity for Mo-S mixed concentrate and is an ideal separation depressant.

SODIUM DITHIONITE AS A PYRITE DEPRESSANT IN GOLD ORE FLOTATION

Sodium dithionite (Na2S2O4) is a widely used reducing agent to control pulp potential (Eh) and pyrite depressant in sulfide ore flotation. In this study, the pyrite depressant effect of sodium dithionite on gold ore flotation was investigated at pH 8 and pH 10.5 comparatively in terms of gold, chalcopyrite, and pyrite recoveries and grades. The presence of sodium dithionite resulted in a drop of approximately 50–70 mV in the Eh values, regardless of the studied pH values, confirming the reducing effect of sodium dithionite. The effects of sodium dithionite on gold and chalcopyrite grades and recoveries were quite limited, especially at pH 10.5. At pH 8, the utilization of sodium dithionite slightly decreased gold and chalcopyrite recovery and grades, while the decrease in pyrite recovery and grades was remarkable. Both pyrite recovery and grade were reduced from 79.5% to 54.7% and 15.3% to 10.7% by the utilization of sodium dithionite at pH 8. In conclusion, it is considered that the selective flotation of gold and chalcopyrite from pyrite can be achieved at a lower pH accompanied by a slightly reduced Eh by the utilization of sodium dithionite.

Fenton oxidation modification mechanism of pyrite and its response to Cu-S flotation separation: Experiment, DFT, XPS and ToF-SIMS studies

Surface modification mechanism of pyrite via Fenton reagent and its response to Cu-S flotation separation was examined in a low-alkaline system using micro-flotation experiments, contact angle, UV–vis, SEM, DFT, XPS, and ToF-SIMS analysis. Flotation and contact angle results proved Fenton reagent could effectively separate chalcopyrite from pyrite at pH = 8. The adsorption rate of hydroxyl radical (•OH) on pyrite surface reached 83.28 %. The SEM results show that flocculent hydrophilic substances were produced on the surface of pyrite after oxidation. Further, DFT calculations results on the basis of interaction between •OH and the pyrite (100) surface showed that strong chemical bonds among the O atom of •OH and the Fe and S atoms on the pyrite surface formed. DMOL3 model and XPS analysis confirmed the oxidation products were primarily found in the form of Fe(OH)3, Fe2O3, Fe(OH)2, Fe2(SO4)3, FeOOH and SO42-, which considerably rejected the adsorption of dixanthogen. The peak intensities of FeOH+ and SO4- both increased to 2312 and 2506. The intensity of C2H5+ ion decreased from 4204 to 1009. Thus, the Fenton reagent triggered the formation of multitude hydrophilic species, and offered a simple access to the pyrite depression. This activity provided a viable option for the Cu-S flotation separation.

Selective depression of pyrite with a novel thiocarbonate in a pyrite-galena flotation system

Eco-friendly depressants suitable for industrial applications are required for the mineral processing industry to achieve sustainable production and environmental protection. Herein, a novel micromolecular organic reagent, sodium O-(2,3,4,5,6-pentahydroxyhexyl) carbonodithioate (SPHC), was synthesised and employed as a selective depressant for pyrite in the flotation separation of bulk galena/pyrite concentrate. Micro-flotation tests demonstrate that SPHC exhibits superior selectivity and depressing ability on pyrite. The adsorption amount of SPHC on the pyrite surface is significantly higher than that on galena in a wide pH range of 4–12, indicating the greater affinity of SPHC on pyrite than on galena. Cyclic voltammetry measurements reveal that SPHC can selectively adhere to the pyrite surface to form hydrophilic products and thereby decrease its floatability. By contrast, the adsorption of SPHC on the galena surface is low and hence its surface hydrophobicity is not altered noticeably. Even in the presence of pre-adsorbed xanthate molecules, the adsorption behaviour of SPHC on both mineral surfaces is hardly affected. Thus, the studied organic depressant not only is an effective depressant for the separation of galena and pyrite but also a promising candidate reagent for the flotation separation of pyrite from other sulphide minerals.

Novel application of depressant sodium mercaptoacetate in flotation separation of chalcopyrite and pyrite

The development of flotation reagents with high selectivity and strong depression ability is of great significance in the efficient enrichment of copper sulfide ores. In this work, a new depressant, sodium mercaptoacetate (SMA) has been explored for the flotation separation of chalcopyrite and pyrite, and the depression mechanism of SMA was studied by Fourier Transform Infrared spectrometer (FTIR), adsorption tests, local electrochemical impedance spectroscopy test (LEIS), Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). Micro-flotation tests showed that SMA strongly depresses pyrite in the pH range of 6–10. When the dosage of SMA is 2.5 × 10−5 mol/L, the dosage of SBX is 1 × 10−5 mol/L, and pH = 6.5, the concentrate with a Cu grade of 31.93% and chalcopyrite recovery of 85.97% can be obtained, in which the pyrite recovery was only 4.18%, respectively. The strong chemical adsorption between SMA and Fe atomic sites exposed on the surface of pyrite reduces the hydrophobicity of pyrite and hinders the adsorption of SBX. In comparison, SMA has less adsorption on the surface of chalcopyrite and hardly affects the further adsorption of SBX. It was shown that SMA could be used as an effective depressant for pyrite in the flotation separation of chalcopyrite and pyrite.

Progressive Hydrophilic Processes of the Pyrite Surface in High-Alkaline Lime Systems.

Pyrite, as a disturbing gangue mineral in the beneficiation of valuable sulfide minerals and coal resources, is usually required to be depressed for floating in flotation practice. Specifically, the depression of pyrite is achieved by causing its surface to be hydrophilic with the assistance of depressants, normally with inexpensive lime used. Accordingly, the progressive hydrophilic processes of the pyrite surface in high-alkaline lime systems were studied in detail using density functional theory (DFT) calculations in this work. The calculation results suggested that the pyrite surface is prone to hydroxylation in the high-alkaline lime system, and the hydroxylation behavior of the pyrite surface is beneficial to the adsorption of monohydroxy calcium species in thermodynamics. Adsorbed monohydroxy calcium on the hydroxylated pyrite surface can further adsorb water molecules. Meanwhile, the adsorbed water molecules form a complex hydrogen-bonding network structure with each other and with the hydroxylated pyrite surface, which makes the pyrite surface further hydrophilic. Eventually, with the adsorption of water molecules, the adsorbed calcium (Ca) cation on the hydroxylated pyrite surface will complete its coordination shell surrounded by six ligand oxygens, which leads to the formation of a hydrophilic hydrated calcium film on the pyrite surface, thus achieving the hydrophilization of pyrite.

The depression mechanism on pyrite in a low-alkaline system with combined depressants: Experiment, HSC, DFT and ToF–SIMS studies

Depression of pyrite in a low-alkaline system has sparked soaring interests for the multi-metal sulfide minerals flotation recently. This study investigates effects of combined depressants (Ca(ClO)<sub>2</sub> and CaO) on pyrite flotation with butyl xanthate (KBX). Micro-flotation experiments indicate that the addition of 200 mg/L combined depressants (a mass ratios of CaO to Ca(ClO)<sub>2</sub> of 2:3) and 1.0×10<sup>−3</sup> mol/L KBX at pH 9.5 can effectively depresses the flotation of pyrite, and a minimum pyrite recovery rate of 12.5% is obtained. Basic thermodynamic evaluation results confirm the participation of Ca(ClO)2 significantly decrease the negative Gibbs free energies of pyrite oxidation reaction. Besides, the calcium species (Ca(OH)<sub>2</sub>, Ca<sup>2+</sup> and Ca(Cl)<sub>2</sub>) will spontaneously transform into CaCO<sub>3</sub>, and it is the ultimate dominant calcium species in the CO<sub>3</sub><sup>2-</sup> system. Density functional theory (DFT) results indicate that CaCO<sub>3</sub> can chemically adsorb onto the pyrite surface with an adsorption energy of –671.13 kJ/mol. The O1 and Ca atoms mainly contribute to the bonding process and are responsible for the stable adsorption of CaCO<sub>3</sub>. ToF-SIMS results provide strong evidence that the combined depressants increase the amount of hydrophilic species and decrease dixanthogen adsorption onto the pyrite surface. The thickness of the whole formed hydrophilic species is approximately 50 nm. Semiquantitative amounts of hydrophilic species follow the order of hydroxy calcium>iron carbonyl>calcium carbonate. Overall, hydrophilic species repulse adsorption of dixanthogen and significantly reduce the flotation performance of pyrite.

Investigating the thermodynamics and adsorption mechanisms of alkaline gelatinised novel depressants on pyrite surface

The depressant-pyrite adsorption thermodynamics, adsorption isotherms, and depression were investigated using adsorption and microflotation studies. The adsorption studies showed that the adsorption of CMC (carboxymthyl cellulose) and LBG (locust bean gum) fit the Freundlich isotherms while CTG (cassia tora gum) fit the Langmuir isotherms as demonstrated by their respective R2. Therefore, CMC and LBG adsorbed onto the pyrite surface by forming both single and multilayer, while CTG adsorbed onto the pyrite surface by creating a monolayer. In addition, the cumulative adsorption densities onto pyrite surfaces were 539, 443, and 372 mg/m2 for CTG, LBG, and CMC, respectively. Furthermore, the thermodynamics studies revealed that all three depressants' adsorption onto the pyrite surface was nonspontaneous and occurred via physisorption, as demonstrated by positive ΔGO and ΔH values < 80 kJmol−1, respectively. Lastly, the percentage of pyrite depression achieved in the microflotation studies decreased in the order LBG > CTG > CMC; their respective values were 87% > 60% > 38%.

Experimental and Machine Learning Studies on Chitosan-Polyacrylamide Copolymers for Selective Separation of Metal Sulfides in the Froth Flotation Process

The froth flotation process is extensively used for the selective separation of valuable base metal sulfides from uneconomic associated minerals. However, in this complex multiphase process, various parameters need to be optimized to ensure separation selectivity and peak performance. In this study, two machine learning (ML) models, artificial neural network (ANN) and random forests (RF), were used to predict the efficiency of in-house synthesized chitosan-polyacrylamide copolymers (C-PAMs) in the depression of iron sulfide minerals (i.e., pyrite) while valuable base metal sulfides (i.e., galena and chalcopyrite) were floated using nine flotation variables as inputs to the models. The prediction performance of the models was rigorously evaluated based on the coefficient of determination (R2) and the root-mean-square error (RMSE). The results showed that the RF model was able to produce high-fidelity predictions of the depression of pyrite once thoroughly trained as compared to ANN. With the RF model, the overall R2 and RMSE values were 0.88 and 4.38 for the training phase, respectively, and R2 of 0.90 and RMSE of 3.78 for the testing phase. As for the ANN, during the training phase, the overall R2 and RMSE were 0.76 and 4.75, respectively, and during the testing phase, the R2 and RMSE were 0.65 and 5.42, respectively. Additionally, fundamental investigations on the surface chemistry of C-PAMs at the mineral–water interface were conducted to give fundamental insights into the behavior of different metal sulfides during the flotation process. C-PAM was found to strongly adsorb on pyrite as compared to galena and chalcopyrite through zeta potential, X-ray photoelectron spectroscopy (XPS), and adsorption density measurements. XPS tests suggested that the adsorption mechanism of C-PAM on pyrite was through chemisorption of the amine and amide groups of the polymer.

Characterization of structure-function properties relevant to copper-activated pyrite depression by different starches

Starches can adsorb on and depress copper-activated pyrite desirably during flotation, an important process in ore mineral extraction. In order to develop structure/function relationships, adsorption on and depression properties of copper-activated pyrite at pH 9 by normal wheat starch (NWS) and high-amylose wheat starch (HAW), dextrin, and a range of oxidized normal wheat starches (peroxide and hypochlorite treated) were investigated. Adsorption isotherms and bench flotation performance were compared with kinematic viscosity, molar mass distribution, surface coverage, and substituted functional groups assay. The differences in molar mass distribution and substituted functional groups among oxidized starches had little influence on the depression of copper-activated pyrite. However, the introduction of -C=O and -COOH substituents, combined with depolymerization, improved solubility and dispersibility, reduced aggregated structures, and strengthened surface binding of oxidized polymers, compared with NWS and HAW. At high concentrations, HAW, NWS, and dextrin were adsorbed onto the pyrite surface more than oxidized starches. However, at the low concentrations of depressant used in flotation, oxidized starches were more effective at selectively masking copper sites. This study suggests that a stable chelation between Cu(I) and starch ligands is necessary for depression of copper-activated pyrite at pH 9, which can be achieved with oxidized wheat starch.

Maximise pyrite depression in copper ore flotation using high salinity water

Numerous copper flotation plants have to use high salinity water, but high salinity water is detrimental to copper flotation by promoting copper activation on pyrite. Despite the effective depression of pyrite by the combined use of sodium metabisulfite (MBS, Na2S2O5) and Hi-Cr steel grinding media in high salinity water, many copper processing plants still desalinate saline water with a considerably high cost, which motivated this study to identify the best chemical solution to maximise the depression of pyrite in copper flotation using high salinity water. Flotation tests and pulp chemistry measurements indicated that the combination of high chromium (Hi-Cr) steel and MBS completely depressed pyrite flotation in high salinity water as achieved by Hi-Cr steel alone in fresh water, but this combination did depress chalcopyrite flotation to some extent. This is because the decomposition of MBS, induced by copper ions, formed strongly oxidising radical species which oxidised both copper-activated pyrite and chalcopyrite. To overcome the drawback of MBS, potassium peroxymonosulfate (PMS, KHSO5) was chosen to depress pyrite in high salinity water in conjunction with forged steel grinding media. This combination also completely depressed pyrite flotation but did not depress chalcopyrite flotation in high salinity water, equivalent to the results achieved by Hi-Cr steel alone in fresh water. This was attributed to the decomposition of PMS predominately induced by iron ions, forming the strongly oxidising radical species which selectively oxidised copper-activated pyrite rather than chalcopyrite.

New insights into pyrite-hydrogen peroxide interactions during froth flotation: experimental and DFT study

Hydrogen peroxide (H2O2) is an efficient depressant for pyrite (FeS2) flotation. However, the depressing mechanism of H2O2 is not fully understood. In this paper, the depressing capacity of H2O2 for pyrite was examined by flotation tests. Results revealed that pyrite flotation could be inhibited by H2O2 at pH 6.4. The pyrite powder in H2O2 solution enhanced the release of O2 from H2O2. However, the O2 concentration in the solution was less than that of H2O2; thus, H2O2 is the major oxidant in the solution. Moreover, density functional theory calculations were performed to study the interactions between H2O2 and hydrated pyrite (100) surface. The H2O2 molecule tended to react with the pyrite surface to generate one S=O bond and an H2O molecule. The possible binding models of O2 molecules on the pyrite (100) surface were also studied for comparison. The O2 dissociation on the pyrite surface was more favorable than the adsorption of O2 as a whole. In addition, the orbital interaction in the S=O bond raised from the reaction of H2O2/O2 with the pyrite surface was also investigated by the density states analysis. These results provide some insights into the oxidizing effect of H2O2 in pyrite flotation.

Separation of copper-sulfur using sodium polyacrylate as pyrite depressant in acidic pulp: Floatability and adsorption studies

This study aimed to investigate the suitability of sodium polyacrylate (PAAS) as a pyrite depressant in a Cu-S separation system through flotation and adsorption experiments. Micro-flotation tests showed that chalcopyrite was selectively separated from pyrite using PAAS as a pyrite depressant in the pH range 2–4. A satisfactory separation effect, a copper concentrate with 30.02% Cu and a recovery of 94.16% was obtained in artificial mixed minerals tests. Adsorption studies showed that PAAS selectively adsorbed on pyrite in the pH range 2–4, while the adsorption on chalcopyrite was weaker, about 6.6 times lower than that on pyrite. PAAS adsorption on pyrite occurred through the interaction between (R-COO−)n and Fe(OH)n(3−n)+ at the solid/liquid interface. Oxidation pretreatment promoted the adsorption of Fe(OH)n(3−n)+ on pyrite, thus providing additional adsorption sites for PAAS and enhancing the adsorption of PAAS on pyrite. After PAAS adsorption, the weak floatability of pyrite in the presence of xanthate was due to the strong hydrophilicity imparted to pyrite by PAAS rather than hindering xanthate adsorption on pyrite.

Froth Flotation of Chalcopyrite/Pyrite Ore: A Critical Review.

In the present work an intense bibliographic search is developed, with updated information on the microscopic fundamentals that govern the behavior of flotation operations of chalcopyrite, the main copper mineral in nature. In particular, the effect caused by the presence of pyrite, a non-valuable mineral, but challenging for the operation due to its ability to capture a portion of collector and float, decreasing the quality of the concentrate, is addressed. This manuscript discusses the main chemical and physical mechanisms involved in the phenomena of reagent adsorption on the mineral surface, the impact of pH and type of alkalizing agent, and the effect of pyrite depressants, some already used in the industry and others under investigation. Modern collector reagents are also described, for which, although not yet implemented on an industrial scale, promising results have been obtained in the laboratory, including better copper recovery and selectivity, and even some green reagents present biodegradable properties that generate a better environmental perspective for mineral processing.