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The aim is to explore new depressants for achieving the efficient separation of apatite and dolomite. In this work, fucoidan (FD) was examined as an eco-friendly dolomite depressant to separate dolomite from apatite. The depression ability and adsorption mechanisms were investigated. The flotation results indicated that FD selectively depressed dolomite. The flotation difference between dolomite and apatite reached 70% approximately at an FD concentration of 75 mg/L. Meanwhile, the recovery and grade of P2O5 reached 89.84% and 32.88% and that of MgO decreased to 1.64% and 34.24% in the artificially mixed minerals test. Wettability, zeta potential, and Fourier transform infrared spectroscopy (FTIR) results revealed that FD tended to adsorb onto dolomite, impeding the interaction of sodium oleate (NaOL) with dolomite, but barely affected that on apatite. Microcalorimetry analysis indicated that the adsorption heat of FD on dolomite was much higher and less time was required to achieve equilibrium. X-ray photoelectron spectroscopy (XPS) results proved that the sulfonic acid radicals within FD chemically interacted with Mg atoms on dolomite while it weakly adsorbed on apatite. [ABSTRACT FROM AUTHOR]

Lepidolite, crucial for lithium extraction, is primarily processed through flotation. However, conventional flotation inhibitors pose environmental challenges. This study introduces Fe(III) as a selective and eco-friendly inhibitor in lepidolite flotation. We investigated its impact on flotation performance and interaction mechanisms with feldspar, quartz, and lepidolite. Adsorption studies revealed that dodecylamine (DDA) selectively adsorbs onto lepidolite when Fe(III) is present. Consistent contact angle and flotation results showed reduced hydrophobicity and recovery rates for feldspar and quartz, with minimal impact on lepidolite. Zeta potential measurements indicated lower potentials for feldspar and quartz compared to lepidolite. Notably, the addition of Fe(III) altered the isoelectric points of quartz and feldspar, suggesting stronger Fe(III) adsorption on these minerals. Infrared spectroscopy and X-ray photoelectron spectroscopy confirmed reduced DDA adsorption on feldspar and quartz surfaces due to Fe(III) adsorption, while DDA adsorption on lepidolite remained largely unaffected. The mechanism underlying Fe(III)'s selective inhibition on feldspar and quartz involves their more negative surfaces compared to lepidolite, which facilitates Fe(III) adsorption and inhibits DDA adsorption. This study offers insights into mechanisms relevant to systems using metal ions as depressants, providing valuable references for similar research. [ABSTRACT FROM AUTHOR]

Given the depletion of high-quality magnesite deposits and the rising demand for high-end magnesium materials, the separation and utilization of high-calcium magnesite ores have become essential. However, the similar surface properties and solubility of semi-soluble salt-type minerals, pose significant challenges for the utilization of dolomite-rich magnesite resources. In this study, 1-hydroxypropane-1,1-diphosphonic acid (HPDP) was identified for the first time as a high-performance depressant for dolomite. Various tests, including contact angle measurements, ζ potential analysis, X-ray photoelectron spectroscopy, and atomic force microscopy, were conducted to elucidate the interfacial interaction mechanisms of HPDP on the surfaces of the two minerals at different scales. Additionally, molecular modeling calculations were used to detail the spatial matching relationship between HPDP and the crystal faces of the two minerals. It was emphasized that HPDP specifically adsorbed onto the dolomite surface by forming calcium phosphonate, ensuring that the dolomite surface remained hydrophilic and sank. Moreover, it was found that the adsorption strength of HPDP on the mineral surfaces depended on the activity of the metal sites and their spatial distribution. These findings provide a theoretical foundation for the molecular design of flotation reagents for high-calcium magnesite ores.

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Depressants are crucial for the selective separation of mineral flotation. Depressants can be classified into organic and inorganic depressants. Inorganic depressants have the disadvantages of toxicity, large dosage, and poor separation efficiency. Therefore, organic depressants are more suitable for mineral separation due to their advantages of biodegradability, comprehensive source, environmentally friendly, and high selectivity. Carboxymethyl cellulose (CMC) is an efficient, nontoxic, and biodegradable mineral-processing depressant widely used in the selective flotation of typical sulfide ores. CMC is one of the essential reagents for cyanide-free and dichromate-free flotation. Therefore, applying and promoting the use of CMC has positive practical significance environmentally. Although research on applying CMC in mineral processing has been conducted in the past, the depression effect of CMC on sulfide ore flotation and its influencing factors have not been systematically summarized. Many sulfide ores frequently coexist with magnesium-containing silicate minerals, such as talc. Adding CMC has a depression effect on sulfide ore and gangue minerals, such as talc. This paper reviews the depression mechanism of CMC on typical sulfide ores, such as galena, chalcopyrite, and pyrite. The results show that the depression effect of CMC on typical sulfide ores is primarily related to the carboxyl and hydroxyl groups in CMC. Both groups depress the typical sulfide ore through hydrogen bonding, electrostatic interaction, and chemical action on the mineral surface. There is a view that the depression of CMC on pyrite relates to its supramolecular conformation. Furthermore, this paper summarizes the depression mechanism of CMC on magnesium-containing silicate gangue. Magnesium silicate gangue, represented by talc, easily clots during grinding, increasing the beneficiation challenges. By adding CMC, the surface wettability can be adjusted and, thus, depress gangue. Finally, this paper systematically expounds on the influence of CMC’s properties, pulp pH, presence of other metal ions, reagent dosage, reagent addition order, and other factors on CMC depression performance in sulfide ore flotation. The summary of the depression effect and influencing factors of CMC can guide and provide a reference for improving the selectivity of reagents and developing new high-efficiency organic depressants. It is of great practical significance to realize the efficient separation of valuable and gangue minerals in sulfide ore flotation.

This paper presents the development of an environmentally friendly, small molecular depressant citrus pectin for improving the recovery of cassiterite resources. Citrus pectin extracted from citrus peel was utilized as the depressant, and it demonstrated significant potential in separating calcite from cassiterite in micro-flotation tests. The molecular weight of the citrus pectin extracted in this paper decreased from 11,485,412 Da to 32,959 Da compared to commercial pectin, resulting in the depressant efficiency of the reagent. The results of a zeta potential and adsorption test indicated that citrus pectin had less and weaker adsorption on the cassiterite surface and could be replaced with NaOL. The chemical adsorption process of citrus pectin on the surface of calcite was determined through FTIR spectroscopy analysis. XPS analysis results indicated that the interaction between the carboxyl groups of citrus pectin and calcium atoms enables adsorption to occur. The AFM revealed that citrus pectin displayed a uniform and dense pattern of point-like adsorption on the surface of calcite. Micro-flotation experiments showed that cassiterite recovery of 80% can be obtained at a citrus pectin dosage of 10 mg/L. Citrus pectin has the advantages of being low-cost, highly selective, and environmentally suitable, making it a promising alternative to conventional reagents. [ABSTRACT FROM AUTHOR]

Abstract Cornstarch is one of the most used depressants in mineral flotation operations. However, corn is a costly input for the Brazilian mineral industry, since its main destination is to serve the animal and human food market and exports. In this study, sorghum and millet, two cheaper starch sources, were tested in order to reduce the mining dependence on corn. A simplex lattice design mixture {3,4} was used to evaluate the best proportion of corn, millet, and sorghum flours to be used as a pyrochlore depressant in relation to the industrially adopted cornstarch (Stargill 6172 supplied by Cargill). Flotation tests were carried out on a bench scale Denver flotation cell. All tests were performed in triplicate in a single rougher stage. The results found suggest that sorghum flour was a stronger pyrochlore depressant compared to corn and millet flours, with an average Nb2O5 content of 1.72 ± 0.05% and recovery of 80.75 ± 4.10%. These values were close to the ones found with Stargill 6172 (1.32 ± 0.02 and 80.95 ± 1.13%, Nb2O5 content and recovery, respectively), the industrially adopted depressant. The marked price and the easiness in the production of the flour in relation to the extraction of starches makes the sorghum flour a potential pyrochlore depressant, replacing the industrially used cornstarch.

Cornstarch is one of the most used depressants in mineral flotation operations. However, corn is a costly input for the Brazilian mineral industry, since its main destination is to serve the animal and human food market and exports. In this study, sorghum and millet, two cheaper starch sources, were tested in order to reduce the mining dependence on corn. A simplex lattice design mixture {3,4} was used to evaluate the best proportion of corn, millet, and sorghum flours to be used as a pyrochlore depressant in relation to the industrially adopted cornstarch (Stargill 6172 supplied by Cargill). Flotation tests were carried out on a bench scale Denver flotation cell. All tests were performed in triplicate in a single rougher stage. The results found suggest that sorghum flour was a stronger pyrochlore depressant compared to corn and millet flours, with an average Nb2O5 content of 1.72 ± 0.05% and recovery of 80.75 ± 4.10%. These values were close to the ones found with Stargill 6172 (1.32 ± 0.02 and 80.95 ± 1.13%, Nb2O5 content and recovery, respectively), the industrially adopted depressant. The marked price and the easiness in the production of the flour in relation to the extraction of starches makes the sorghum flour a potential pyrochlore depressant, replacing the industrially used cornstarch. [ABSTRACT FROM AUTHOR]

A depressant is essential to the effective flotation-based separation of ilmenite and forsterite, based on their comparable physicochemical characteristics. In this work, dextran sodium sulfate (DSS) was initially introduced as a depressant, to aid in the separation of ilmenite and forsterite. Comparing the DSS to conventional natural starch, the results indicate that the forsterite exerts a greater depression over the ilmenite. The difference in recovery of ilmenite and forsterite was 75.44% at 10 mg/L of DSS dosage. The DSS was chemisorbed strongly onto the forsterite surface via Mg active sites, whereas its interaction with the ilmenite surface via physisorption was weak, based on the XPS and molecular-dynamics-simulation analyses. The results of the AFM and QCM-D investigations showed that the DSS adsorption layer on the forsterite surface was larger than those on the ilmenite surface. Consequently, DSS may function as a depressant, to effectively separate forsterite from ilmenite ore. [ABSTRACT FROM AUTHOR]

In this study, GX2 was applied as a new high-efficiency chalcopyrite depressant to selectively separate molybdenite from Cu-Mo sulfide ores. The flotation performance and its interaction mechanisms with chalcopyrite and molybdenite were investigated using single-mineral and artificial-mixed-ore flotation, contact angle measurements, zeta-potential measurements, infrared spectroscopy, and X-ray optoelectronic spectrum analysis. The results indicated that molybdenite could be selectively separated from chalcopyrite under the optimal flotation conditions of pH 9.0, 80 mg/L GX2, 20 mg/L kerosene, 10 mg/L MIBC, and a flotation time of 3 min, while the molybdenite and chalcopyrite recoveries were around 90% and 5%, respectively. It was confirmed that GX2 could save ten times the depressant dosage compared to that of the Na2S baseline to achieve a similar separation efficiency. The contact angle test, zeta potential, infrared spectrum, and XPS results show that GX2 may be adsorbed on the surface of chalcopyrite via chemical adsorption, and the hydrophilic substances formed change its hydrophobicity, whereas the effect on the floatability of molybdenite is small, resulting in the excellent separation efficiency of chalcopyrite and molybdenite via flotation. [ABSTRACT FROM AUTHOR]

To address the issue of mediocre separation efficiency of depressants in the copper-lead separation process, this article synthesized a macromolecular organic depressant, polymaleic anhydride-ethylenediaminetetraacetic acid (PMA–EDTC), using a polycarboxylic macromolecule as the backbone and also introducing –N–(C=S)–S– as the solidophilic group and employed as a galena depressant. The structure of PMA–EDTC was characterized using Fourier transform infrared (FT-IR). The effect of PMA–EDTC on the floatability of galena and chalcopyrite was investigated through micro-flotation and Contact angle measurements. The experimental results demonstrated that PMA–EDTC exhibited selectivity inhibition towards galena rather than chalcopyrite across a wide pH range. At a dose of 8 mg/L, there was effective separation between galena and chalcopyrite with a separation coefficient of 24.17, effectively altering the floatability of galena while having little impact on the floatability of chalcopyrite. The selective inhibition behavior and adsorption mechanism of PMA–EDTC on galena and chalcopyrite were investigated using FT-IR, Zeta potential, and X-ray photoelectron spectroscopy (XPS). FT-IR and Zeta potential studies indicated that PMA–EDTC formed chemical adsorption on the surface of galena. XPS confirmed the model of chemical adsorption of PMA–EDTC on lead atoms in the galena surface. The results indicate that PMA–EDTC adsorbs on the surface of galena via its –(C=S)–S–group, forming a hydrophilic complex and achieving selective depression of lead and the cleaning flotation of copper. [ABSTRACT FROM AUTHOR]

Alkaline gelatinisation is the easiest, cheapest, fastest, and most energy-efficient form of polymer modification. It uses sodium hydroxide to change the polymer's structure to improve its properties. Cassia tora and locust bean gums are known for their gelling properties. Hence, this study developed a novel, comprehensive mathematical process model to produce high-purity alkaline gelatinised products using response surface methodology. The individual and interactive effects of water, sodium hydroxide, gelatinisation time, and polymer amount on product purity were investigated. A four-factor central composite design was used for the alkaline gelatinisation experiments. The results showed that the optimised conditions which yielded a high-purity product were water amount of 100 ml, NaOH of 10 ml, polymer amount of 5 g, and gelatinisation time of 5 min, respectively. This combination yielded a gelatinisation product with ∼100% dry purity. Furthermore, the coefficient of determination (R2) value of 0.9922 in the present study proves that the model was adequate and suitable. Therefore, this model may be used to navigate the design space.

Phosphate ore is an important strategic mineral resource. The efficient utilization of phosphate resources faces challenges such as low grade of raw ore and difficulty in discharging gangue minerals. One of the key problems to be solved urgently in the reverse flotation of phosphate ore is the effective depression of apatite. However, research on the influence mechanism of acid depressants on the surface properties and adsorption characteristics of apatite is still insufficient. In this study, the influence of different depressants (such as sulfuric acid, phosphoric acid or mixed acid of sulfur acid and phosphorus acid) on the flotation separation performance of an artificial mixture of apatite and dolomite (gangue mineral) was investigated through laboratory flotation tests. On this basis, with the addition of different depressants, the contact angle, zeta potential, XPS and TOC were used to investigate the surface wettability, surface charge, surface species and the adsorption characteristics of the collector (sodium oleate) on the apatite surface, and, accordingly, the inhibiting mechanism was discussed. The results show that, when mixed acid of sulfur acid and phosphorus acid is used as a depressant, a concentrate with a P2O5 grade of 33.53% and a recovery of 88.92% can be obtained, and the parameters are better than when using phosphoric acid with a P2O5 grade of 30.15% and a recovery of 80.12% or sulfuric acid with a P2O5 grade of 30.12% and a recovery of 80.58%. Our analysis shows that the mixed acid has the best inhibiting effect on apatite, which is mainly due to the following: (a) after adding the mixed acid, chemicals such as CaSO4, CaHPO4/Ca(H2PO4)2 are generated on the surface of apatite, resulting in a significant reduction in the contact angle and stronger surface hydrophilicity; (b) the mixed acid reduces the zeta potential of apatite, produces new species and weakens the non-selective adsorption of negatively charged oleate on the surface of apatite, thus preventing the apatite from floating. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the development of an environmentally friendly, small molecular depressant citrus pectin for improving the recovery of cassiterite resources. Citrus pectin extracted from citrus peel was utilized as the depressant, and it demonstrated significant potential in separating calcite from cassiterite in micro-flotation tests. The molecular weight of the citrus pectin extracted in this paper decreased from 11,485,412 Da to 32,959 Da compared to commercial pectin, resulting in the depressant efficiency of the reagent. The results of a zeta potential and adsorption test indicated that citrus pectin had less and weaker adsorption on the cassiterite surface and could be replaced with NaOL. The chemical adsorption process of citrus pectin on the surface of calcite was determined through FTIR spectroscopy analysis. XPS analysis results indicated that the interaction between the carboxyl groups of citrus pectin and calcium atoms enables adsorption to occur. The AFM revealed that citrus pectin displayed a uniform and dense pattern of point-like adsorption on the surface of calcite. Micro-flotation experiments showed that cassiterite recovery of 80% can be obtained at a citrus pectin dosage of 10 mg/L. Citrus pectin has the advantages of being low-cost, highly selective, and environmentally suitable, making it a promising alternative to conventional reagents.

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The traditional hematite depressant starch has the disadvantages of poor solubility and high viscosity. In this study, a novel hematite depressant, pullulan, with better performance and flotation effect than starch was found. The structure, molecular weight and viscosity of pullulan were determined for its characterization. The results of flotation tests revealed that the flotation separation of hematite-quartz by pullulan was better than that of starch for hematite-quartz. The selective depression mechanism of pullulan on hematite was studied by contact angle measurement, zeta potential measurement, FT-IR analyses and XPS analyses. Overall, the weak adsorption of pullulan on quartz did not affect the adsorption of DOPA on the quartz surface. However, it was adsorbed strongly on hematite surface and hindered the adsorption of DOPA. This selective adsorption led to a much greater hydrophobicity of quartz than hematite in the reverse flotation, resulting in the separation of quartz and hematite. Pullulan was adsorbed by chemical bonding between its hydroxyl group and iron sites on the hematite surface. Thus, compared with starch, pullulan was easy to dissolve in water, had low viscosity and good flotation effect, so it was a better hematite depressant. [ABSTRACT FROM AUTHOR]

Abstract Pyrite is separated from other minerals mainly by flotation. However, the hydrophilicity of pyrite is affected by many factors, causing it to easily enter the concentrate and consequently reduce the quality of concentrate. Highly efficient pyrite depressants can be selectively adsorbed on the surface of pyrite to improve its hydrophilicity, thereby increasing the flotation separation efficiency. Understanding the fundamental inhibition mechanism of depressants on pyrite is a prerequisite to improve the flotation desulfurization efficiency. The inhibition ability and mechanism of different types of pyrite depressants are reviewed in this manuscript. In recent years, molecular simulation has increasingly become a powerful tool to study the interaction between reagents and minerals, shedding new light on the adsorption mechanisms of reagents on mineral surfaces at the atomic and electronic levels. The properties of sulfide mineral and flotation reagents as well as the microscopic adsorption mechanistic studies of reagents on mineral surfaces based on quantum chemistry and molecular simulation are also reviewed.

Environmentally achieving the flotation separation of chalcopyrite and galena is always a difficult problem due to the similar floatability of the two minerals. To conquer the problem, maleic acid–acrylic acid copolymer (MA/AA), an eco-friendly reagent, was applied as a potential depressant for flotation separation of chalcopyrite from galena for the first time. Single-mineral flotation tests exhibit that MA/AA has a much better depression ability and selectivity than those of traditional galena depressants (Na2S and K2Cr2O7), which can inhibit the floatability of galena well but barely affects the flotation behavior of chalcopyrite in a wide pH range (7–11). A satisfying flotation separation effect of artificially mixed galena and chalcopyrite was realized by using MA/AA as a depressant. Based on a series of measurements including zeta potential, XPS, and contact angle, it appears that MA/AA was much more inclined to be chemically adsorbed on the surface of galena than that of chalcopyrite, which restrains the further adsorption of collectors on galena. In contrast, for chalcopyrite, the low adsorption of MA/AA hardly affects the further adsorption of collectors. According to these findings, MA/AA is considered to be potentially applicable as an effective and eco-friendly depressant in the industrial flotation separation of chalcopyrite and galena. [ABSTRACT FROM AUTHOR]

Effect of sodium polyacrylate (PAAS) on the flotation and surface properties of serpentine was studied systematically by means of flotation test, Zeta potential test, Infrared spectral (IR) and SEM-EDS analysis. The flotation results showed that the addition of the depressant sodium polyacrylate could effectively depress the flotation of serpentine, and the recovery of serpentine decreased from 36% to 10% after the addition of 24.7 mg/L sodium polyacrylate. Zeta potential test results showed that sodium polyacrylate could significantly reduce the surface charge of serpentine.Infrared spectral (IR) and SEM-EDS analysis showed that sodium polyacrylate had obvious chemical adsorption on serpentine surface.The mechanism analysis shows that sodium polyacrylate can flocculate serpentine by interacting with the Mg2+ on the serpentine surface, and change the dispersion state of serpentine particles, thus effectively depressing the serpentine particles.

[Display omitted] • M−DEP was first synthesized and used as a novel depressant for the separation of molybdenite and talc. • M−DEP had an excellent selective depression effect on molybdenite. • The adsorption behavior and mechanism of M−DEP on specific crystallographic plane of talc and molybdenite was studied. • M−DEP adsorbed on "basal" and "edge" surface of molybdenite by hydrophobic and chemical interaction, respectively. The separation of talc and molybdenite is a challenging and research hotspot in mineral processing. In the work, a nitrous acid ester depressant (M−DEP) was first synthesized and used as a molybdenite depressant for the separation of talc and molybdenite via reverse flotation. Flotation tests of single-mineral and multi-mineral samples were carried out to evaluate the effect of M−DEP on the flotation behavior of molybdenite and talc. Zeta potential, X-ray photoelectron spectroscopy, and Fourier Transform Infrared Spectroscopy were used to analyze the selective depression mechanism of M−DEP on molybdenite and talc. Furthermore, the adsorption behavior of M−DEP on specific crystallographic planes of minerals has been studied by contact angle, atomic force microscope, and DFT calculation. Flotation experiment results indicated that M−DEP had excellent selective depression on molybdenite in the pH range of 5 to 10. The results of mechanism analysis showed that M−DEP could be adsorbed on molybdenite "basal" surface by hydrophobic interaction, and on molybdenite "edge" surface by chemical interaction, while could not be adsorbed on the surface of talc due to electrostatic repulsion. M−DEP enlarged the surface floatability difference between talc and molybdenite and promoted the efficient separation of talc and molybdenite via reverse flotation. [ABSTRACT FROM AUTHOR]

• Pullulan was a green and efficient depressant of hematite in DDA reverse flotation. • Pullulan could enhance the hydrophilicity of the hematite surface. • Pullulan could adsorb on hematite surface through hydrogen bonding and chemical bonds. As the uncertainly of climate and the world situation intensifies, there are more and more pressures on resources and environment faced by human beings, the requirements for the development of mineral resources have become higher and higher. Iron mineral, as the most exploited mineral by mankind at present, the green and efficient purification of iron ore is an important means to realize energy saving and carbon reduction. In this paper, a novel hematite depressant—Pullulan (an environment friendly microbial polysaccharide, represented as PU thereafter), was introduced into the purification of hematite from quartz in cationic collector flotation system. Furthermore, a serious of surface tests were applied to explore the adsorption mechanisms between PU and the mineral surfaces. According to these experiments, it can be concluded as follows. The results of micro-flotation exhibited that PU showed better inhibition for hematite in DDA flotation system, the concentrate product with Fe grade of 65.88 %, and 91.06 % recovery was obtained from the artificial mixed minerals at 20 mg/L DDA, 15 mg/L PU at natural slurry pH. Wettability analysis suggested that PU could enable the hematite surface to become more hydrophilic, while little effect on wettability changes were observed on the quartz surface. The zeta-potential, FTIR and XPS analyses revealed that PU could occur adsorption on the hematite surface relying on hydrogen bonding with the hydrated hematite surface, and chemical complexation formed between the hydroxyl groups on PU and the Fe sites of the hematite surface. [ABSTRACT FROM AUTHOR]

In order to achieve the effective separation of copper-molybdenum in the presence of xanthate and kerosene, carrageenan was explored as a novel environmentally friendly molybdenite depressant in this work. The flotation behavior of molybdenite was studied by micro-flotation tests, and the depression mechanism was investigated through zeta potential, Fourier Transform Infrared Spectroscopy (FTIR) and atomic force microscope (AFM) analysis. The flotation results showed that molybdenite was significantly depressed by carrageenan in the pH range of 6–12 even in the presence of xanthate and kerosene. Zeta potential, FTIR and AFM measurement demonstrated that carrageenan could adsorb strongly on the molybdenite surface and change the surface wettability of molybdenite, thus significantly reducing the floatability of molybdenite. [ABSTRACT FROM AUTHOR]

Although studies on starch have developed in polymer chemistry research, their structure-activity relationship remains indistinct in the flotation depressants field. In this work, the utilization of five types of causticized starches from different botanical sources as depressants in the flotation of pentlandite/serpentine pure mineral systems was studied. The branched chain length of the starches was quantitatively analyzed using a high-performance anion-exchange chromatography system, and the average branched chain lengths of the causticized starches were obtained. The flotation results demonstrated that the depression effect of all causticized starches on serpentine had a positive correlation with the average branched chain length. Zeta potential tests, FTIR experiments, and XPS analysis confirmed that the causticized starches with a longer branched chain were absorbed more strongly on the serpentine surface. In the present study, the influence of branched chain length on the depression effect of causticized starch was investigated, which deepened our understanding of the depression mechanism of traditional macromolecule depressants and will promote the development of new macromolecule depressants. [ABSTRACT FROM AUTHOR]

Persons who use drugs are a high-risk subpopulation for HIV infection because more than one drug user often take drugs together, which increases the risk of HIV transmission. For the PWUDs who had tested for HIV, we extracted data on demographic characteristics, drug types, injection drug use behavior, encrypted IDs of co-users, and drug use location from the National Dynamic Management and Control Database for Persons Who Use Drugs between January 2008 and July 2016. We mapped and classified Co-UDs’ networks and estimated the risk of HIV infection. Drug co-use networks were formulated on the basis of connections between PWUDs at the same time and location. Latent profile analysis (LPA) and logistic regression models were used to cluster the classes and to estimate the HIV infection risk among them, respectively. A total of 470 967 PWUDs were included, among whom 69 529 Co-UDs formed 7 001 networks, which were categorized into three classes: Class A (n = 211, 3.0%) had large networks, with more members (median 10.0 (IQR: 8.0-14.5)), and comprised depressant and stimulant users located in central and eastern China; Class B (n = 3 770, 53.8%) was dominated by depressant users (median 3.0 (IQR: 3.0-4.0)) across the country; Class C (n = 3 020, 43.1%) was dominated by stimulant users (median 3.0 (IQR: 3.0-4.0)) located in central and eastern China. The HIV infection rates were 9.71%, 3.33%, and 0.33% in Classes A, B, and C, respectively. Compared with Class A, Classes B and C were associated with decreased odds of HIV infection. Our findings suggest that more attention should be paid to larger networks, with a relatively high HIV infection risk, to enhance prevention and intervention strategies.

We have investigated the effective utilization potential of carbon nanomaterials in the field of pour point depressants, and reported three kind of carbon-based hybrid nano-pour-point depressants with different dimensions. In this paper, poly-α-olefins-acrylate high-carbon ester pour point depressant (PAA-18) was prepared by esterification and polymerization as the basic pour point depressant. Then, the basic pour point depressant PAA18 was modified by solvothermal method with graphene oxide (GO), carbon nanospheres (Cna) and carbon nanotubes (OCNTs). The morphology and structure of the composites were analyzed by SEM, FTIR and XRD. The results showed that PAA18 was successfully in situ polymerized on GO, Cna and OCNTs. We took the simulated oil as the experimental object, and evaluated its pour point, rheological properties and wax crystal morphology, and achieved excellent results. In the three carbon-based hybrid nano-pour-point depressants with different carbon contents, the oxidation carbon nanotubes composite pour point depressant (PAA18-1 % OCNTs) with carbon content of 1 % had the best pour point and viscosity reduction effect when the dosage was 1250 ppm, which could make the pour point of the simulated oil containing wax decrease by 16 °C. PAA18-1 % OCNTs reduced the pour point by 5 °C more than PAA18. This paper provides reference for the application of carbon nanomaterials in the field of pour point depressant.

Through flotation tests and desorption tests, the desorption behavior of methylcellulose from the surface of talc at different temperatures and its influence on the flotation of talc were studied. The results show that the natural floatability of talc is good. The depressive effect on methylcellulose on talc is enhanced with the increase of pulp temperature. Washing can weaken the depressive effect on methylcellulose on talc, increase the flotation recovery of talc, and increase the flotation recovery of talc more at low temperature. The flotation separation of chalcopyrite and talc can be realized by using methylcellulose.

Our recent studies revealed that the ground sulphide minerals in contact with water generate H2O2 but its effect on the oxidation of pulp components and hence in deteriorating the concentrate grade and recovery in flotation has not been explored yet. The use of Na2S reductant at the grinding stage is thought to control the deleterious effects of H2O2 in the pulp liquid. Therefore, the effect of Na2S addition during grinding stage on the formation of H2O2 and its influence on sulphide complex ore flotation was investigated. The results showed that the presence of Na2S increases the formation of H2O2 but decreases the dissolved oxygen. An increase in Na2S dosage in grinding, the Pb grade and recovery in Cu-Pb concentrate is decreased while pyrite is depressed marginally better. These changes in flotation response of sulphides have been discussed and explained with the formation of H2O2 quantitatively.

Zinc is an important raw material and nonferrous metal that has an extremely important role in the development of national economies. For this reason, countries around the world continue to strengthen their research efforts on the development and utilization of zinc resources. Sphalerite is an important source of zinc metal, which often coexists with chalcopyrite, galena, and pyrite in nature. The flotation separation of complex polymetallic sulfide ore is a difficult problem in the field of mineral processing engineering. To achieve the flotation separation of chalcopyrite, galena, and other minerals from sphalerite, depressants are needed. Due to the difficulty of activation after the depression of galena and other sulfide ores, a zinc depression and lead floatation process is usually used. The choice of the sphalerite depressant is critical when separating zinc and other sulfides. The traditional sphalerite depressants are generally inorganic. Although these depressants significantly improve the hydrophilicity of the sphalerite surface and strongly depress the sphalerite, they have a certain inhibitory effect on other sulfide ores while depressing the sphalerite. In addition, these agents are difficult to degrade and have a negative impact on the environment. To achieve high-efficiency flotation separation of sphalerite and sulfide minerals and improve the quality of the concentrate products, the development of new inhibitors is becoming increasingly important. Thence, the effect of the oxidizer potassium permanganate and organic depressant sodium alginate on the flotation of three kinds of sulfide minerals are studied, including chalcopytite, galena, and sphalerite. The investigations involved flotation tests, X-ray photoelectron spectroscopy (XPS) analysis, adsorption behavior analysis, with an additional focus on the mechanism of potassium permanganate strengthening, and sodium alginate depression of sphalerite flotation. The flotation results show that adding either an oxidizer or sodium alginate alone does not enable the selective depression of sphalerite. However, adding a certain amount of oxidizer and sodium alginate together can realize the selective coordinated depression of sphalerite, with little effect on the flotation of chalcopytite and galena. The XPS analysis results show that sodium alginate is chemically adsorbed on the sphalerite surface with oxidation products such as zinc oxide, zinc hydroxide, or zinc sulfate, but is not adsorbed on an unoxidized sphalerite surface. The adsorption test results show that the preoxidation of potassium permanganate on sphalerite significantly increases the adsorption capacity of sodium alginate on the sphalerite surface. Therefore, potassium permanganate can strengthen the sodium alginate depression of sphalerite flotation.

Carrollite is often associated with chalcopyrite, and their natural floatability is similar, which makes it difficult to separate the two minerals by flotation in industrial production. In this study, the depression behavior and mechanism of flaxseed gum (FG) introduced as carrollite depressant on carrollite and chalcopyrite in PBX flotation system was investigated through micro-flotation, zeta potential, total organic carbon (TOC), fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). The flotation results indicated that FG was a highly effective depressant to separate 92.39 % chalcopyrite from the mixture with carrollite at pH 9.0 with a reagent scheme of 50 mg/L of FG and 8.0 × 10−5 mol/L of PBX. The zeta potential and TOC analysis results demonstrated that both carrollite and chalcopyrite exhibited a favorable affinity to FG, and pre-treated FG significantly hindered the adsorption of PBX on carrollite, while only slightly decreased that on chalcopyrite, resulting in the considerable difference in floatability between carrollite and chalcopyrite. In addition, FT-IR spectra and XPS detection results further confirmed that the affinity of FG towards carrollite superior to PBX might be due to the bidentate coordination of the carboxyl groups in FG with Co sites on carrollite surface, whereas the interaction between its carboxyl groups and Cu sites on both minerals was very weak or did not happen. Therefore, FG was promising in flotation separation of copper-cobalt sulfide minerals as a new friendly efficient depressant. [Display omitted] [ABSTRACT FROM AUTHOR]

The traditional hematite depressant starch has the disadvantages of poor solubility and high viscosity. In this study, a novel hematite depressant, pullulan, with better performance and flotation effect than starch was found. The structure, molecular weight and viscosity of pullulan were determined for its characterization. The results of flotation tests revealed that the flotation separation of hematite-quartz by pullulan was better than that of starch for hematite-quartz. The selective depression mechanism of pullulan on hematite was studied by contact angle measurement, zeta potential measurement, FT-IR analyses and XPS analyses. Overall, the weak adsorption of pullulan on quartz did not affect the adsorption of DOPA on the quartz surface. However, it was adsorbed strongly on hematite surface and hindered the adsorption of DOPA. This selective adsorption led to a much greater hydrophobicity of quartz than hematite in the reverse flotation, resulting in the separation of quartz and hematite. Pullulan was adsorbed by chemical bonding between its hydroxyl group and iron sites on the hematite surface. Thus, compared with starch, pullulan was easy to dissolve in water, had low viscosity and good flotation effect, so it was a better hematite depressant.

In this paper, the potential of sulfonated naphthalene formaldehyde (SNF) condensate as a depressant in the flotation separation of scheelite from calcite was verified and investigated. The results of microflotation experiments showed that SNF had a stronger depressant performance on calcite than a conventional depressant—water glass and had an excellent performance in fine-grained particles (−0.037 mm) treatment. Adsorption tests were conducted to quantitatively study the selective adsorption of SNF on the surface of scheelite and calcite. At 200 mg/L SNF, the adsorption density of SNF on the calcite surface reached 5.48 mg/g, which was more than four times than that of scheelite. In addition, compared with scheelite, the adsorption of SNF on the calcite surface had a more significant negative effect on the contact angle. Moreover, infrared (IR) measurements combined with X-ray photoelectron spectroscopy (XPS) analysis were performed to investigate the adsorption mechanisms of SNF on scheelite and calcite surfaces. The results showed that the adsorption of SNF on scheelite was more likely to be physical attraction, while the –SO3− group in SNF could chemically react with Ca species on the surface of calcite, resulting in a stronger adsorption than on scheelite. [ABSTRACT FROM AUTHOR]

The superplasticizer sulfonated acetone formaldehyde condensate (SAF) was first used as a depressant in the selective flotation of scheelite and calcite in this paper. First, single mineral flotation tests were performed to compare the depressing performance of SAF and the traditional depressant water glass. Results showed that both −0.074 + 0.037 mm and −0.037 mm particles could be well treated by SAF with more satisfactory results than that of water glass. Contact angle test results showed that SAF could amplify the wettability difference between scheelite and calcite surfaces. Then, the effect of SAF on the surface electrical properties of scheelite and calcite was studied by zeta-potential tests. SAF could negatively charge the calcite surface before adding the collector and hinder the subsequent adsorption of the collector while having little effect on the scheelite. Moreover, microscopic analysis of slurry suspensions showed that SAF could prevent calcite particles from forming hydrophobic agglomerates to achieve the dispersion of gangue minerals. Finally, the selective adsorption effect of the SAF on the calcite and scheelite surfaces was studied by surface analysis using FTIR (Fourier transform infrared) and XPS (X-ray photoelectron spectroscopy). Results showed that Ca2+ on the calcite surface was the main adsorption site for the chemisorption of sulfonic acid groups in SAF. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Brazil is among the world's largest iron ore producers. The standard concentration method is reverse cationic flotation using amines, and their derivatives, such as quartz collector and corn (as either grits, flour, or starch) as the hematite depressant. Corn is considered cheap, abundant, and available all around the country. However, its demand has been abruptly increasing over the last few years, mainly due to the emerging of new attractive markets, such as ethanol production. In order to propose a feasible replacement for corn, hematite and quartz samples from the Brazilian Iron Quadrangle were tested in a modified Hallimond tube using millet starch as depressant for the first time (corn and sorghum starch were used as benchmark). Tests were carried out with four different depressant dosages and four different pHs, all in triplicate. It was possible to reach quartz floatability above 98% and hematite depressability above 93% for millet and sorghum starches. This fundamental study shows that replacing corn with millet poses a real opportunity to reduce operational costs.

Pyrite is separated from other minerals mainly by flotation. However, the hydrophilicity of pyrite is affected by many factors, causing it to easily enter the concentrate and consequently reduce the quality of concentrate. Highly efficient pyrite depressants can be selectively adsorbed on the surface of pyrite to improve its hydrophilicity, thereby increasing the flotation separation efficiency. Understanding the fundamental inhibition mechanism of depressants on pyrite is a prerequisite to improve the flotation desulfurization efficiency. The inhibition ability and mechanism of different types of pyrite depressants are reviewed in this manuscript. In recent years, molecular simulation has increasingly become a powerful tool to study the interaction between reagents and minerals, shedding new light on the adsorption mechanisms of reagents on mineral surfaces at the atomic and electronic levels. The properties of sulfide mineral and flotation reagents as well as the microscopic adsorption mechanistic studies of reagents on mineral surfaces based on quantum chemistry and molecular simulation are also reviewed. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• HDTMP was firstly used as a calcite depressant in scheelite flotation. • HDTMP had very little adsorption on scheelite and chelated with Ca2+ in slurry. • HDTMP had stronger chemical and hydrogen bonding interaction with calcite. Scheelite, a strategic calcium-bearing mineral, usually coexists with calcite. Froth flotation is the most commonly used method of separating scheelite from calcite, but it is difficult to selectively separate them because of their similar Ca active sites. Sodium silicate with a high dosage and low selectivity is usually used as calcite depressant, which leads to the loss of scheelite and formation of stable colloidal dispersions of fine particles in the tailings slurry, making tailings treatment difficult. Therefore, this work developed a novel depressant, hexamethylenediamine tetramethylene phosphonic acid (HDTMP or H 6 L), which is a hexabasic acid. The flotation results of single mineral and binary mixed minerals showed that HDTMP at a concentration of 2 × 10−5 mol/L could selectively depress calcite with 4 × 10−5 mol/L NaOL at pH 10.0. Adsorption capacity, Ca2+ concentrate, and contact angle measurements showed that HDTMP was adsorbed more on calcite. Zeta potential measurement and solution chemistry calculations indicated that HL5− anion was the main active species of HDTMP at pH 10.0. Density functional theory (DFT) calculations further revealed that HDTMP had stronger interaction with calcite through chemically bonding with Ca sites and hydrogen bonds (P-O⋯H water and P-O H⋯O calcite) formed by the phosphate groups in HDTMP and H/O atoms on calcite surfaces. Therefore, HDTMP presents substantial potential for practical applications as a novel calcite depressant in scheelite flotation. [ABSTRACT FROM AUTHOR]

Sodium carboxymethyl cellulose (CMC) is a potential depressant which is an indispensable reagent for the treatment of complex refractory iron ores during reverse flotation. In this study, the interaction force between hematite particles adsorbed with CMC and bubbles was calculated, thereby revealing the inhibitory mechanism of CMC on hematite particles. When dodecylamine (DDA) was 15 mg/L and CMC was 3 mg/L, pH=10, the content and recovery rate of hematite reached 83.25% and 87.41%, respectively. Zeta potential tests showed that adsorption of CMC hindered the adsorption of DDA on hematite. AFM images visualized the adsorption status and adsorption layer thickness of CMC on the surfaces of hematite and quartz. FTIR results indicated that the adsorption of CMC on the surface of hematite was strong chemical adsorption, but the adsorption on quartz was physical adsorption. Based on the extended DLVO theory, the total potential of interaction between hematite particles adsorbed with CMC and bubbles was measured. The calculation results demonstrated that the hydration repulsion interaction potential owing to the adsorption of CMC dominated the total potential energy, preventing the adhesion of hematite and bubbles. [Display omitted] [ABSTRACT FROM AUTHOR]

In industry, the content of P 2 O 5 , mainly derived from apatite, must not exceed 0.5% in spodumene concentrate. Strong acid leaching of phosphorus-containing minerals with the disadvantages of seriously harming the environment and high investment in equipment, is the main method for removing phosphorus. Therefore, in this work, sodium alginate (SA) depressant was effectively used to depress spodumene and float apatite. Li 2 O grade and recovery in the spodumene concentrate were 6.18% and 87.66% obtained by the binary mixed mineral flotation tests with 1.1 × 10−4 mol/L SA and 3 × 10−4 mol/L sodium oleate (NaOL) collector at pH 5. The P 2 O 5 content in the real spodumene concentrate could be reduced from 4.58% to 0.49% using 500 g/t of SA. The contact angle tests showed that the hydrophilicity of spodumene increased after the treatment of SA. Zeta potential and atomic force microscope (AFM) measurements revealed that anionic SA had more adsorption on the spodumene surface and hindered the subsequent adsorption of NaOL. Density functional theory (DFT) calculations further showed that SA could chelate with Cu2+ pre-adsorbed on the spodumene surface to form a 4-membered ring. Therefore, the method of reverse flotation has great application potential in the dephosphorization of high-phosphorus lithium concentrate. [Display omitted] • SA selectively depressed spodumene but barely influenced apatite flotation. • SA with stronger adsorption on spodumene hindered subsequent NaOL adsorption. • SA chelated with Cu2+ pre-adsorbed on spodumene to form a 4-membered ring. • SA realized comprehensive utilization of high-phosphorus spodumene ore. [ABSTRACT FROM AUTHOR]

Brazil is among the world's largest iron ore producers. The standard concentration method is reverse cationic flotation using amines, and their derivatives, such as quartz collector and corn (as either grits, flour, or starch) as the hematite depressant. Corn is considered cheap, abundant, and available all around the country. However, its demand has been abruptly increasing over the last few years, mainly due to the emerging of new attractive markets, such as ethanol production. In order to propose a feasible replacement for corn, hematite and quartz samples from the Brazilian Iron Quadrangle were tested in a modified Hallimond tube using millet starch as depressant for the first time (corn and sorghum starch were used as benchmark). Tests were carried out with four different depressant dosages and four different pHs, all in triplicate. It was possible to reach quartz floatability above 98% and hematite depressability above 93% for millet and sorghum starches. This fundamental study shows that replacing corn with millet poses a real opportunity to reduce operational costs. [ABSTRACT FROM AUTHOR]

Introduction: The plant Peganum harmala is a shrub native to the arid parts of the world including India. It’s therapeutic value is attributed to the presence of alkaloids harmala and harmine in the dried ripe seeds. In traditional medicine these seeds are considered to have anti-spasmodic, hypnotic, anodyne, emetic, emmenogogue, stimulant, aphrodisiac, lactogogue and antihelminthic actions. Objectives: The present study was undertaken to find out the effects of the active principle extracted from the seeds of Peganum harmala on isolated cardiac muscle and skeletal muscle preparations and the probable mechanism of action Materials & Methods: The harman alkaloid isolated from Peganum harmala seeds was used for experiments on isolated preparations of frog heart and frog rectus abdominis muscles and the responses were recorded on a rotating smoked drum on a kymograph. Results: The Harman alkaloids were shown to inhibit the normal contractions and also the inotropic actions of Adrenaline, 5HT and calcium on isolated frog heart. These have not shown any effect on the frog rectus abdominus muscle either on their own or on the contractions induced by Acetylcholine. Conclusion: Harman alkaloids have cardio-depressant activity, it is unlikely that these alkaloids have a specific receptor antagonistic activity. Also these have found to inhibit the cardiac muscle contractions but not the skeletal muscle contractions. The cardio-depressant action may be due to calcium channel blockade

• HEDP exhibits excellent depressing performance for dolomite rather than magnesite. • Magnesite can be effectively separated from dolomite by flotation with HEDP. • HEDP is adsorbed strongly by chelating with Ca sites exposed to the dolomite surface. • The adsorption of NaOl onto dolomite is hindered by the pre-adsorption of HEDP. • A adsorption model of HEDP for separating magnesite from dolomite is proposed. This research focused on the adsorption features and depression mechanism of 1-hydroxyethylene-1,1-diphosphonic acid (HEDP) used as a novel dolomite depressant on dolomite and magnesite surfaces, to extend the application of HEDP for the selective flotation of magnesite from dolomite. The depression impacts of HEDP on the flotation behaviors of the two minerals were investigated through micro-flotation tests. The flotation results indicated that, when sodium oleate (NaOl) was used as the collector, HEDP displayed an outstanding depression effect on the dolomite flotation, whereas it had only a slight influence on the magnesite flotation. Dolomite and magnesite could be efficiently separated at approximately pH 10 with a reagent scheme of 200 mg/L HEDP and 120 mg/L NaOl. The selective depression mechanism of HEDP for dolomite was revealed using contact angle, X-ray photoelectron spectroscopy (XPS), zeta potential, and infrared spectrum (IR) analyses. The results from the contact angle tests indicated that HEDP selectively reduced the surface hydrophobicity of dolomite in the NaOl system. Besides, zeta-potential measurements and IR analyses revealed that the addition of HEDP prior to NaOl had no significant impact on the adsorption of NaOl onto magnesite; however, this addition strongly prevented NaOl from being adsorbed onto dolomite, resulting in a significant difference in the flotation performances of the two minerals. Furthermore, crystal chemistry calculations and XPS analyses confirmed that the strong adsorption of HEDP on the dolomite surface could be attributed to the interaction between the HEDP electron-rich groups and the calcium species exposed to dolomite. Thus, HEDP could be used as a high-performance depressant for the dolomite flotation to realize the decalcification of the magnesite flotation. [ABSTRACT FROM AUTHOR]

In this investigation, micro-flotation, zeta potential measurements, adsorption tests, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS) were used to assess the separation mechanism of ilmenite and titanaugite using a novel cationic reagent, 2-amino-1,3-propanediol (APD). The micro-flotation results of single mineral and artificially mixed minerals demonstrated that APD had a negligible impact on ilmenite flotation, whereas it significantly reduced the recovery of titanaugite, resulting in the selective flotation of ilmenite from titanaugite. Zeta potential measurements indicated a significant positive shift in the titanaugite surface potential following interaction with APD, whereas the ilmenite surface potential exhibited a minimal change in the pH range between the isoelectric point (IEP) of the two minerals. The adsorption test demonstrated that a higher quantity of APD adsorbed onto the titanaugite surface than that of ilmenite. Moreover, APD adsorbed onto the titanaugite surface via chemical interaction with active sites containing Ca and Mg, which was confirmed by FTIR and XPS analysis. Overall, APD exhibits favorable adsorption characteristics on the surface of titanaugite through a combination of electrostatic attraction and chemical interaction, whereas its interaction with ilmenite is hindered by electrostatic repulsion. It is hoped that this study will contribute to the development of highly efficient flotation depressants targeting titanaugite in the field of ilmenite flotation. [Display omitted] • A cationic reagent, APD was used as a novel depressant for titanaugite. • APD exhibited an excellent depression to titanaugite at pH 5.0. • APD adsorbed on the surface of titanaugite through a combination of electrostatic attraction and chemical interaction. • Using depressant APD efficiently separated ilmenite from titanaugite [ABSTRACT FROM AUTHOR]

Separating chalcopyrite and molybdenite is difficult owing to their similarly high floatability. Accordingly, this paper considers the depressant 2-Amino-5-mercapto-1,3,4-thiadiazole (AMT), in order to separate chalcopyrite and molybdenite and investigate the relevant mechanism of AMT depression. Single-mineral flotation tests showed that when kerosene was used as the collector and AMT as the depressant, molybdenite showed excellent flotation while chalcopyrite was completely depressed. Mixed mineral flotation tests showed that separation of these two minerals could be achieved when AMT was applied as the depressant. Combining the test results of adsorption, Zeta potential, and XPS, the mechanism of AMT depression is suggested. Therefore, the adsorption mechanism of AMT on the chalcopyrite and molybdenite can be revealed. The adsorption of AMT on the chalcopyrite surface is unquestionably greater than that on the molybdenite surface. The results suggest that AMT is chemisorbed on chalcopyrite surfaces through the Cu-S bonds. By contrast, physisorption on molybdenite surfaces is through electrostatic action. Thus, selective depression of chalcopyrite can be achieved with the use of AMT. This study promises a more environmentally friendly flotation separation process for chalcopyrite and molybdenite. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, the pyrolysis liquid of pine (PLP) was used as a novel depressant to separate fluorite from calcite. Flotation experiments revealed that the PLP can depress the flotation of calcite, whereas its impact on fluorite was minimal. Fourier transform infrared (FTIR) spectroscopy showed that the substance adsorbed onto calcite surface hindered oleate adsorption onto calcite, but had minimal impact on fluorite. Gas chromatography-mass spectrometry analysis results presented that the main components of PLP were phenols, aldehydes, furans, and ketones. Among them, catechol and other phenolic compounds played major roles in the depression of calcite as revealed by FTIR and time-of-flight secondary ion mass spectroscopy. The increased phenol content resulted in a more pronounced depressant effect of PLP prepared at 800 °C on calcite compared with that of PLP prepared at 500 °C. This study provides a new perspective on the potential application of pyrolysis fluid in mineral flotation. [Display omitted] • Pyrolysis liquid of pine (PLP) was innovatively used as depressant in ore flotation filed. • PLP can reduce calcite recovery to below 10%, while the fluorite recovery is above 90%. • The main active components in PLP were phenols and furaldehydes. • PLP selectively adsorb on calcite surface and prevents the collector adsorption. [ABSTRACT FROM AUTHOR]

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]

O-Carboxymethyl chitosan (O-CMC), a nontoxic and biodegradable derivative of the natural polysaccharide-chitosan, was recently found to be a viable alternative for the toxic depressants used in the flotation separation of chalcopyrite and molybdenite. In this work, the adsorption characteristics of O-CMC on molybdenite/chalcopyrite surfaces and the associated interaction mechanisms were investigated by electrokinetic study, infrared spectroscopy, Atomic force microscopy (AFM) imaging, X-ray photoelectron spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The experimental results demonstrated that O-CMC adsorbed on both mineral surfaces. However, the interactions between O-CMC and chalcopyrite are mostly weak physical interactions such as electrostatic interaction, and most of the adsorbed O-CMC molecules can be removed mechanically (e.g., washing) or displaced by xanthate. In comparison, the adsorption of O-CMC on molybdenite is dictated by hydrophobic interaction and electrostatic interaction, and is barely affected by rinsing or xanthate addition. As a result, the strong adsorption of O-CMC on molybdenite over the chalcopyrite lead to the depression of molybdenite and selective separation of two minerals in flotation. In addition, infrared spectroscopy and XPS revealed that no strong chemical interactions were involved during the adsorption O-CMC on molybdenite and chalcopyrite surfaces. [ABSTRACT FROM AUTHOR]