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Pyrite depression in copper ore flotation often requires large doses of inorganic depressants that lead to high toxicity, high costs, and low selectivity. Thus, this study offers a novel pyrite depressant, polyglutamic acid (PGA), in the selective flotation of chalcopyrite with xanthate as a collector. The flotation and adsorption mechanism on chalcopyrite and pyrite were systematically studied using a series of flotation tests, zeta potential measurements, adsorption analysis, infrared spectral (IR) analysis, and X-ray photoelectron spectroscopy (XPS) analysis. The addition of PGA depressed the flotation of pyrite more strongly than chalcopyrite in the wide pH range of 8–12. In the presence of PGA, selective separation between the two minerals was achieved at pH 9, and the recovery of chalcopyrite was over 85% and that of pyrite was less than 20%. All of the surface analysis techniques indicated that PGA interacted differently with the two minerals and the surface of pyrite adsorbed a much greater amount of PGA than that of chalcopyrite. Prior addition of PGA significantly reduced the adsorption of the collector on the pyrite surface and thus depressed its flotation. However, the significant adsorption of the collector and its oxidation to dixanthogen on the chalcopyrite surface caused its improved flotation even in the presence of PGA. Therefore, PGA, which is a non-hazardous, biodegradable, and renewable reagent, could be used as an alternative pyrite depressant in Cu–Fe conventional flotation circuits. • PGA achieves improved selective separation of chalcopyrite (Clp) and pyrite (Pyr). • Polyglutamic acid (PGA) is a nontoxic and degradable depressant of Pyr flotation. • Clp adsorbs much greater amount of xanthate than Pyr in the presence of PGA. • PGA could be an alternative depressant in Cu–Fe conventional flotation circuits. [ABSTRACT FROM AUTHOR]

Highlights • TCSS achieves improved selective separation of chalcopyrite (Clp) from pyrite (Py). • Tricarboxylate sodium starch (TCSS) is a biodegradable depressant of Py flotation. • Clp adsorbs more xanthate collector than Py in the presence of TCSS depressant. Abstract In the flotation of copper sulfides, pyrite is often activated by Cu2+ ions dissolved from copper-bearing minerals in alkaline media (pH ˃ 9), which results in pyrite entering the copper concentrate. To reduce the floatability of pyrite, we designed a novel functionally modified biopolymer, tricarboxylate sodium starch (TCSS), that showed superior depression selectivity towards pyrite in low pH solutions when employed in Cu–Fe flotation separation in the presence of sodium butyl xanthate (SBX) as a collector. TCSS depressed the floatability of pyrite more strongly than that of chalcopyrite in single mineral flotation in the pH range 4–6. The most selective separation was achieved at pH ∼ 6; the recovery of Cu in the concentrate was over 77%, and the grade was improved to 24.50% compared to the initial feed grade of 12.50%. Surface characterization analyses, including zeta potential, X-ray photoelectron spectroscopy (XPS) analysis, and Fourier transform infrared (FTIR) spectroscopy, confirmed the different degrees of interaction of TCSS with the two minerals. TCSS was adsorbed on the pyrite surface, possibly via a chemisorption mechanism, as reflected in the FTIR and XPS analyses. The adsorption of TCSS passivated the pyrite surface, which inhibited the adsorption and oxidation of the collector. On the other hand, the adsorption and oxidation of the collector on chalcopyrite surface were effective even in the presence of TCSS, attesting to the weak interactions between chalcopyrite and TCSS. [ABSTRACT FROM AUTHOR]

Copper and lead are two important and widely used metals in industry. Chalcopyrite (CuFeS2) is associated with galena (PbS) in ore, and it has been a research hotspot in separating galena from chalcopyrite by flotation. In this study, the flotation behaviors of chalcopyrite and galena were studied through flotation tests, adsorption measurements, solution chemistry calculation, Fourier transform infrared spectroscopy (FTIR) and molecular dynamics (MD) simulations. The results show that the floatability of chalcopyrite is better than that of galena in the presence of O-isopropyl-N-ethyl thionocarbamate (IPETC), and the recovery difference between chalcopyrite and galena is about 20% when IPETC is 7 x 10-4 mol/L at pH 9.5, while the floatability difference between the two minerals is significant. Competitive adsorption of OH- and IPETC on mineral surfaces leads to lower floatability of galena than that of chalcopyrite. IPETC is able to remove the hydration layer on mineral surfaces and then adsorb on active sites. The floatability of minerals is enhanced with the increase of their hydrophobicity. This study provides a reference to separate galena from chalcopyrite. [ABSTRACT FROM AUTHOR]

The microbial ecology of the bioleaching of chalcopyrite ores is poorly understood and little effort has been made to handle the microbiological components of these processes. In this study, the composition and structure of microbial communities in acid mineral bioleaching systems have been studied using a PCR-based cloning approach. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA gene fragments from bacteria was used to evaluate the changes in the bacterial community in the process of chalcopyrite bioleaching in a shaken flask system. The results revealed that the bacterial community was disturbed after the addition of chalcopyrite. Phylogenetic analyses of 16S rRNA gene fragments revealed that the retrieved sequences clustered together with the genera Acidithiobacillus, Leptospirillum, and Acidovorax. Multidimensional scaling analysis of DGGE banding patterns revealed that the process of chalcopyrite bioleaching in 46 days was divided into four stages. In the first stage, Leptospirillum were dominant. In the second stage, Leptospirillum and Acidithiobacillus groups were mainly detected. In the third and fourth stages, the bacterial community was relatively stable and was dominated by Leptospirillum and Acidithiobacillus. These results extend our knowledge on the microbial dynamics in chalcopyrite bioleaching, a key issue required to improve commercial applications. [ABSTRACT FROM AUTHOR]

• Study sheds new light on development and optimization of green depressants for flotation technology. • Research offers new low cost green depressants for sulfide minerals flotation separation. • Synthetic molecules depress pyrite flotation more strongly and selectively than chalcopyrite. • Costs and environmental impacts can be minimized by the use of synthetic depressants. 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 H 2 O 2 as the oxidant and FeSO 4 ·7H 2 O 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. [ABSTRACT FROM AUTHOR]

The rejection of pyrrhotite and pyrite has become a long-standing problem in the copper ore industry. This paper describes the first successful depression and adsorption mechanism of a novel and non-hazardous reagent, polyglutamic acid (PGA), on pyrrhotite in the selective flotation of chalcopyrite with xanthate as the collector, making use of various laboratory-scale measurement techniques. The addition of PGA inhibited the flotation of pyrrhotite much more strongly than that of the chalcopyrite in a wide pH range. The prior addition of PGA achieved an improved selective flotation of chalcopyrite from pyrrhotite at pH 8, at which the grade and recovery of chalcopyrite in concentrate were over 80%. Surface measurement techniques including XPS spectral, IR spectral, zeta potential, and reagent adsorption analyses indicated that the PGA interacted differently with the two minerals, and had much greater affinity towards pyrrhotite than chalcopyrite. The presence of PGA blocked the electrochemical activity of the collector on the pyrrhotite surface and thus depressed its flotation, whereas the adsorption of the collector and its oxidation to dixanthogen were more effective on the chalcopyrite surface, indicating a weaker interaction of PGA with chalcopyrite. Our results suggest that the application of PGA could replace the toxic inorganic depressants in flotation technology, and could significantly reduce the environmental impacts of processing. [ABSTRACT FROM AUTHOR]

During smelting, arsenic in copper concentrates affects the product quality and causes environmental pollution. Removing arsenic minerals from copper concentrates requires environmental-friendly and cost-effective depressants for flotation separation. Ca(ClO)2 was combined with sodium humate (SH) to improve the flotation separation of chalcopyrite from arsenopyrite. Results of single-mineral flotation indicated that combined Ca(ClO)2 and SH significantly inhibited arsenopyrite and exerted a negligible effect on chalcopyrite. The arsenic content in copper concentrates significantly decreased from 63% to 11% in the absence of a depressant and in the presence of Ca(ClO)2 and SH, as proven by the mixed-mineral flotation results. SH can adsorb on both mineral surfaces as indicated by the zeta potential measurements and Fourier transform infrared spectroscopy. However, the presence of Ca(ClO)2 increased the adsorption of arsenopyrite compared with chalcopyrite. The arsenopyrite floatability depressed with the Ca(ClO)2 oxidation and subsequent SH adsorption, as verified by X-ray photoelectron spectroscopy. Results of flotation tests confirmed that the chalcopyrite surface was slightly oxidized, but it remained hydrophobic. The combination of depressants has the potential for industrial application. [ABSTRACT FROM AUTHOR]

A novel surfactant, thiocarbonohydrazide (TCH), was synthesized and tested for the first time as a selective chalcopyrite depressant in Cu-Mo separation. Its adsorption mechanisms on chalcopyrite were studied by flotation tests, zeta potential, FTIR, XPS and ToF-SIMS measurements. FTIR and zeta potential analyses suggested that there was a strong chemisorption reaction between TCH and chalcopyrite, resulting in the formation of TCH–copper complexes. XPS and ToF-SIMS measurements further confirmed the chemisorption of TCH onto the chalcopyrite surface and showed that this chemisorption reaction is due to its S and N atoms, which form five-membered chelating rings by releasing H ions. [ABSTRACT FROM AUTHOR]

The present research aims at recovering copper by reprocessing of tailings at China Molybdenum Co. Ltd. (CMOC) from bench-scale to industrial tests. It focuses on the determination of the reagents' dosage and pulp concentration that enables to obtain the highest recovery of copper by flotation of the studied tailings. Based on the results of bench-scale tests, commissioning and industrial tests were conducted at CMOC and satisfactory results were achieved. Compared to the prior year's database, it was concluded that the reprocessing of tailings by flotation appeared to be an attractive practice because it could enable to minimize the footprint of mineral processing on the local environment. Meanwhile, the reprocessing of tailing could generate an extra profit of $1,205 800 per year for CMOC. Furthermore, the application of this technique at Sanqiang flotation plant was considered to be successful. These results indicate that the studied tailings represents an important source of secondary raw material for the extraction of copper and it opens up an alternative way for greening copper extraction. Finally, it is proved that the reprocessing of tailing by flotation is reliable, economical and promising in copper extraction industry, and therefore, cleaner production of copper concentrate is feasible. [ABSTRACT FROM AUTHOR]

The flotation response of chalcopyrite and molybdenite when using a novel compound, acetic acid-[(hydrazinylthioxomethyl)thio]-sodium (AHS), as the depressant was investigated through micro-flotation and batch flotation in this study. The depressing mechanisms were studied by means of zeta potential, FTIR and XPS measurements. The micro and bench flotation results indicated that AHS exhibited a strong influence on the depression of chalcopyrite and had little effect on the flotation of molybdenite minerals; these results might be attributed to the significant improvement of the molybdenite/chalcopyrite selectivity index after the addition of AHS. The results of the FTIR spectra, zeta potential and XPS measurements indicated that AHS chemisorbs onto the chalcopyrite surface through its S and N atoms, forming a five-membered cheat ring. A possible depressant mechanism along with a postulated adsorption mode for the surface interaction between AHS and chalcopyrite are provided. [ABSTRACT FROM AUTHOR]

In the present study, we investigated the replacement of NaCN with pure depressant and depressant systems in the flotation separation of Cu-Mo bulk concentrate supplied by China Molybdenum Co., Ltd on a laboratory scale. The contrast experiments between the developed depressant system and NaCN were conducted in open circuit, and the results indicated that the developed depressant system achieved the similar Cu removal efficiency (cyanide 94.07% and developed reagent scheme 91.34%) and Mo recovery (cyanide 93.61% and developed reagent scheme 93.14%), which exhibited the advantages of environmental compatibility and economic adaptability. The results of FTIR spectra and XPS indicated that the chemical adsorption process may dominate the interaction of depressant with chalcopyrite, and a possible depressant mechanism is predicated along with a postulated adsorption mode for the surface interaction between disodium carboxymethyltrithiocarbonate (DMTC) and chalcopyrite. [ABSTRACT FROM AUTHOR]

Abstract: A quantitative structure–activity relationship (QSAR) study of selectivity in flotation of chalcopyrite from pyrite for xanthates and xanthate derivatives was performed. The genetic function approximation (GFA) algorithm was applied to select the descriptors and to generate the correlation models. Three combinations of topological, structural, physicochemical, spatial and electronic descriptors were applied. Six QSAR models with acceptable R 2 correlation coefficients and Q 2 cross-validation correlation coefficients (R 2 >0.75, Q 2 >0.6) were developed. The models show that shadow area fraction YZ, LUMO density of carbonyl oxygen atom and Hirshfeld Fukui indices (+) of thiocarbonyl sulfur atom are the three most significant variables for the selectivity. The descriptor shadow area fraction YZ revealed that the planar structure is important for the selectivity. The descriptors LUMO density of carbonyl oxygen atom and Hirshfeld Fukui indices (+) of thiocarbonyl sulfur atom demonstrated LUMO distributions over carbonyl oxygen atom should be large for favorable selectivity. This study concluded that selectivity of xanthates and xanthate derivatives is determined by the strength of the dative bonding between copper atom on the chalcopyrite surface and carbonyl oxygen atom of these collectors and the stability of the six-member ring formed as a result. [Copyright &y& Elsevier]

This paper presents a study on the relation between bacterial adhesion force and bioleaching rate of chalcopyrite, which sheds light on the influence of interfacial interaction on bioleaching behavior. In our research, Acidithiobacillus ferrooxidan s ( A . ferrooxidan s) were adapted to grow with FeSO 4 ·7H 2 O, element sulfur or chalcopyrite. Then, surface properties of Acidithiobacillus ferrooxidans and chalcopyrite were analyzed by contact angle, zeta potential and Fourier transform infrared spectroscopy (FTIR). Adhesion force between bacteria and chalcopyrite was measured by atomic force microscopy (AFM). Attachment and bioleaching behaviors were also monitored. The results showed that A . ferrooxidan s adapted with chalcopyrite exhibited the strongest adhesion force to chalcopyrite and the highest bioleaching rate. Culture adapted with sulfur bacteria took second place and FeSO 4 ·7H 2 O-adapted bacteria were the lowest. Bioleaching rate and bacterial attachment capacity were positively related to bacterial adhesion force, which is affected by the nature of energy source. According to this work, the attachment of bacteria to chalcopyrite surface is one of the most important aspects that influence the bioleaching process of chalcopyrite. [ABSTRACT FROM AUTHOR]

Abstract: The efficiency of copper leaching is improved by bacteria attached to chalcopyrite. Therefore, the study of the attachment mechanism to control leaching is important. The adhesion of three species of leaching microorganisms including Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans to chalcopyrite was investigated by using atomic force microscopy (AFM). The forces were measured with tip-immobilized cells approached to and retracted from the mineral. The results show that both the surface charge and the hydrophobicity of bacteria cells influence the adhesion force. Furthermore, the adhesion force decreased in case the extracellular polymeric substances (EPS) had been removed. In addition, the data indicate that the amount of attached cells increased with increasing adhesion force. [Copyright &y& Elsevier]

• HEDP was for the first time applied in the separation of chalcopyrite from pyrite. • HEDP exhibited a higher selectivity than widely used ethyl xanthate (EX). • HEDP showed a weaker adsorption on pyrite but a stronger one on chalcopyrite. Ethyl xanthate (EX) is a widely used collector in the flotation of sulfide minerals. However, it also has the disadvantages of low selectivity and harm to human health. Screening and/or designing more selective and green collectors is a 'hot topic' in mineral processing field. In this work, 1-Hydroxyethylidene-1, 1-diphosphonic acid (HEDP), a cheap green reagent widely used in water treatment, was for the first time, applied in the flotation separation of chalcopyrite from pyrite. In addition, a comparative test of the traditional EX collector was also carried out. Flotation results of single mineral and binary mineral mixture showed that HEDP possessed a better selectivity for the separation of chalcopyrite from pyrite than EX. Zeta potential measurement results indicated that HEDP exhibited a stronger adsorption on chalcopyrite and a weaker interaction with pyrite. Hence, HEDP is a promising collector that possesses the potential to replace EX in future chalcopyrite flotation practice. [ABSTRACT FROM AUTHOR]