Search

Depressants are essential additives in the flotation separation of scheelite-calcite minerals. However, traditional inorganic depressants such as sodium silicate have the disadvantages of high dosage, environmental pollution, and being non-efficient, which leads to a growing interest in eco-friendly and effective organic alternatives. In this study, a polysaccharide, dextrin, was used as a green depressant for the flotation separation of scheelite from calcite. Micro-flotation experiments indicated that dextrin selectively depressed calcite at natural pH yet scheelite remained floatable using sodium oleate (NaOL) as a collector. Adsorption density and zeta potential results indicated that dextrin was preferentially adsorbed on the calcite surface and prevented the subsequent NaOL from adsorption. By contrast, dextrin had a weak interaction with scheelite, allowing NaOL to be adsorbed on the scheelite surface. Fourier transform infrared spectroscopy (FTIR) analysis and density functional theory (DFT) calculations suggested that the Ca2+ active sites on the calcite surface interacted with -OH groups on the carbon ring of dextrin. X-ray photoelectron spectroscopy (XPS) tests confirmed the chemical interaction between -OH groups in dextrin and Ca2+ active sites on the mineral surfaces, and importantly, the interaction was much stronger for calcite than for scheelite. [ABSTRACT FROM AUTHOR]

In general, fine coal with high ash is usually difficult to clean because of kaolin in the flotation pulp. It is necessary to find some effective methods for the high-precision flotation of coal from kaolin. In this investigation, sodium polyacrylate (PAAS) was selected as a selective flocculant and depressant for fine kaolin in coal flotation pulp. Focused beam reflectance measuring instrument (FBRM), particle video microscope (PVM), infrared spectrometer, contact angle measuring instrument and scanning electron microscope (SEM) were used to reveal the interaction between sodium polyacrylate and coal or kaolin. The results show that with the increase in concentration, PAAS could adsorb on the surface of kaolin through hydrogen bonding, which promoted the formation of fine kaolin particles into flocs, and reduced the surface area of kaolin. PAAS had a dispersing effect on coal. PAAS inhibited the flotation behavior of kaolin, and the flotation index was optimal when the dosage of PAAS was 20 mg/L. Adding an appropriate dosage of PAAS into the coal flotation system can form kaolin floccules, which reduced the entrainment of kaolin in clean coal by water flow, thereby improving the flotation selectivity of coal from kaolin. [ABSTRACT FROM AUTHOR]

Apatite is the most important phosphate mineral and flotation serves as the primary method for separating it from its predominant gangue mineral, calcite (CaCO3). In this study, the direct flotation of pure samples of apatite and calcite was studied using a micro flotation system. Fatty acid collectors were confirmed to be highly effective for the flotation of apatite and calcite minerals. The collectors Aero 825, Oleic acid, Potassium amyl xanthate (Z6), FS-2, Armac C, Hexa Decyl Amine, Sodium oleate, Corn oil, Armofelote 18, Dirol, Alke, and Atrac 1580 were applied in the experiments. Aero 825 at a concentration of 100 g/t for calcite and the Atrac at a concentration of 400 g/t for apatite provided the most optimal flotation conditions. Recoveries of calcite and apatite were 93% and 83%, respectively. After achieving the maximum recovery for each mineral, the depression capabilities of various depressants on both minerals were separately examined. Sodium hexametaphosphate (SHMP), Sodium silicate, Iron (II) sulfate, Sodium carbonate, Calcium chloride 2-hydrate, Carboxymethylcellulose (CMC), Sodium dodecyl sulfate (SDS), Aluminum sulfate 18-hydrate, Phosphoric acid, Sulfuric acid, Oxalic acid dihydrate, Tartaric acid, Lactic acid, Starch, Dextrin, Hydrochloric acid, and Sodium hydroxide were applied as depressants. SHMP for calcite and both Lactic acid and Oxalic acid dihydrate for apatite provided the best depression conditions. The recoveries of calcite and apatite were reduced to 10% and 25%, respectively. Calcite flotation kinetics is followed by the first-order kinetics model and apatite flotation kinetics is followed by the first-order with rectangular distribution and the second-order with rectangular distribution kinetics models. [ABSTRACT FROM AUTHOR]

Talc is a naturally hydrophobic mineral. Its separation from sulfide minerals is a tough issue in froth flotation. In this study, calcium lignosulphonate (CLS) was introduced as a talc depressant during sodium isobutyl xanthate (SIBX) flotation of chalcopyrite. The micro-flotation findings showed that under pH 5.0–10.5, the combination application of CLS and SIBX achieved a selective flotation separation of chalcopyrite from talc. The results of zeta potential, contact angle, adsorption capacity and in-situ AFM deduced that both talc and chalcopyrite exhibited a favorable affinity toward CLS, and SIBX hardly changed the adsorption of CLS on talc surface, while significantly reduced that on chalcopyrite. The Ca2+ ions of CLS played a bridging role in connecting lignosulphonate (LS) anions and the negatively charged Si-O layers through electrostatic attraction, which transformed talc surface from hydrophobicity into hydrophilicity. The Cl− ions weakened the adsorption of LS anions on the Ca2+-modified talc surface, and the adsorption affinity of Na+ ion toward the Si-O layers was much weaker than that of Ca2+ ion. Thus, CLS exhibited the strongest depression against talc's floatability, followed by CaCl2 + SLS (sodium lignosulphonate), and then SLS. SIBX chemisorbed on to chalcopyrite via forming the surface Cu-IBX complexes, which removed the adsorbed LS anions and recovered the floatability of chalcopyrite. The CLS-hydrophilized talc and SIBX-hydrophobized chalcopyrite exhibited the different surface wettability, and they both loaded negative charges, which prevented the aggregation of their particles, resulting in a highly efficient flotation separation chalcopyrite from talc. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing 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 Mining & Metallurgical Engineering is the property of Mining & Metallurgical Engineering 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.)

The following is an abstract of the study. The objective of this study was to identify the chemical constituents of Jasmine Leaves and predict their potential sedative effects. A rapid chemical analysis identified the compounds present in Jasmine Leaves. A database was created to establish "target‐disease" and "compound‐target" networks. Four machine learning models were developed and evaluated to predict the sedative potential of various compounds. Molecular docking was performed on the two most promising compounds identified through network analysis and their respective targets. A total of 34 compounds were identified in Jasmine Leaves. Eight compounds, including citric acid and Pogostone, were identified as being associated with genes involved in the process of sedation. The Random Forest (RF) model showed the best performance, with an accuracy of 0.75, an F1 score of 0.76, an AUC of 0.83, a sensitivity of 0.70, a specificity of 0.72, a precision of 0.77, and an MCC of 0.42. The model predicted the potential sedative effects of citric acid and Pogostone with probabilities of 0.51 and 0.29, respectively. Molecular docking results indicated that citric acid and Pogostone had strong interactions with tyrosinase and gamma‐aminobutyric acid type A (GABAA) receptors, with MOE software scores of −3.83 and −4.18, respectively. This study concludes that a rapid assessment method was developed to evaluate the pharmacological potential of natural products, suggesting that Jasmine Leaves may exert sedative effects through interactions between citric acid and Pogostone with tyrosinase and GABAA receptors. Additionally, Jasmine Leaves show promise as a cost‐effective sleep aid beverage. [ABSTRACT FROM AUTHOR]

Molybdenum is a very important strategic material, the composition of its associated elements Is very complex, China's largest reserves of porphyry molybdenum deposits are mostly copper-molybdenum associated deposits, but due to the fact that copper and molybdenum minerals often have similar natural floatability, their séparation has become a major challenge, the addition of Cu-Mo separation depressant provides an effective method for their separation, and with the concept of green environmental protection, people pays more and more attention to the protection of resources and environment, which also has higher requirements for the types, depressant mechanism and performance of Cu-Mo separation depressants. In this paper, the research progress of Cu-Mo separation depressants in recent years have been reviewed, from the aspects of chalcopyrite inorganic depressants, organic depressants, novel depressants, combined depressants and molybdernite depressants, also gives a review on depressing mechanism and industrial applications in Cu-Mo mines. This review aims to provide reference for further research and industrial application in this field. [ABSTRACT FROM AUTHOR]

Copyright of Mining & Metallurgical Engineering is the property of Mining & Metallurgical Engineering 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 Mining & Metallurgical Engineering is the property of Mining & Metallurgical Engineering 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.)

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.

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]

Chalcopyrite and galena are primary raw materials for producing Cu and Pb metals, respectively. Flotation is still the main method to recover these two minerals. So far, lots of work has been done to recover them from low-grade refractory ores, whereas the efficient separation of these two minerals remains a major challenge. In this review, the crystal, surface, floatability and needed reagents were discussed. Firstly, the crystalline structures were introduced, including physical and chemical properties, and followed by surface properties from a density functional theory simulation perspective. As reviewed, the surface properties were closely related to their floatability, such as the degree of surface oxidization, particle size, galvanic interactions, metal ions, and so on. Moreover, the floatability of minerals could be influenced by flotation reagents, and therefore a range of new collectors and depressants were described. The review aimed to provide a deep understanding on the factors affecting Cu/Pb flotation separation as well as to develop new depressants helping to guide the flotation separation of Cu/Pb/Zn polymetallic sulfide ores for researchers. [ABSTRACT FROM AUTHOR]

Copyright of GeSec: Revista de Gestao e Secretariado is the property of Sindicato das Secretarias e Secretarios do Estado de Sao Paulo (SINSESP) 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.)

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.

In nature, arsenopyrite commonly acts as a companion mineral of chalcopyrite. As the arsenic in arsenopyrite easily exudes during the smelting process, arsenic will not only pollute the environment but also seriously affect human health once it flows into the nature, so it is important to realize the separation of arsenopyrite and chalcopyrite. Flotation is the most efficient and commonly used means to separate these two minerals. As the floatability of arsenopyrite is similar to that of chalcopyrite, the two are usually separated using depressants to suppress arsenic and float copper. The commonly used inorganic depressants in the separation process of copper and arsenic have drawbacks such as poor selectivity, strong toxicity, and environmental pollution. Therefore, the development of a clean, efficient and non-toxic inhibitor is the key to the separation of copper and arsenic. Ethylenediamine tetramethylene phosphoric acid (EDTMP) was developed as a novel depressant of arsenopyrite to achieve the separation of arsenopyrite and chalcopyrite. Micro-flotation experiments and artificial mixture flotation tests verified the flotation performance of EDTMP, and the mechanisms of EDTMP adsorbed on arsenopyrite and chalcopyrite surface were revealed by Zeta potential, FTIR spectrum, and XPS measurements. The flotation experiments revealed that EDTMP could effectively depress the flotation of arsenopyrite without affecting chalcopyrite at pH = 10 and SIBX concentration of 200 mg/L, and the results of zeta potential and FTIR spectrum indicated that EDTMP is preferred to adsorb on arsenopyrite, which hindered the adsorption between SIBX and arsenopyrite. XPS results showed that EDTMP chemisorbed on arsenopyrite surface in the form of P-O-Fe bonds, while EDTMP weakly physisorbed on chalcopyrite surface. EDTMP was a novel arsenopyrite depressant, which was highly efficient, clean, and environmentally friendly compared to traditional depressants. [ABSTRACT FROM AUTHOR]

With the increasing scarcity of easy separation ores, utilization of refractory ores need to be solved urgently. A difficult-to-beneficiate ore in Heilongjiang has the features of high oxidation rate, low-grade of molybdenum, uneven grain size distribution, and difficult in separation of copper and molybdenum. The ore has not been exploited for many years, caused a great waste of resources. The low-grade molybdenum ore contains 0.033% molybdenum and 0.014% copper. The molybdenum minerals in the ore mainly exist in the form of molybdenite, grain size is 0.01 - 0.50 mm, the average oxidation rate is 18.89 %. Copper minerals mainly exist in the form of chalcopyrite, grain size is 0.005 - 0.15 mm, the floatability of chalcopyrite is excellent, and the molybdenum concentration is difficult. According to the characteristics of the uneven size distribution of molybdenum minerals and fine particle size of copper minerals, a process flowsheet of "coarse grinding and roughing + fine grinding and cleaning" was designed, regarding chalcopyrite has the characteristics of good floatability and is difficult to inhibit. Inhibition effect of various copper depressants on copper-bearing minerals was investigated. The research find that new agent HL120 has the main component of hydroxylated xanthate with hydrophilic and hydrophilic groups, it is easier to adsorb on the surface of chalcopyrite, which can inhibit chalcopyrite more effectively. Using HL120 to inhibit chalcopyrite in molybdenum flotation, a molybdenum concentrate containing 48.87% Mo and 0.26% Cu with a molybdenum recovery of 82.43% was finally obtained. Study on flotation of the molybdenum tailings obtained a copper concentrate containing 16.88% Cu with copper recovery 81.27% for the operation and 47.66% for the raw ore. The low-grade ore was effectively utilized, and the economic benefits of the enterprise were significantly improved. [ABSTRACT FROM AUTHOR]

The flotation behavior of apatite, a main mineral source of phosphorus, is strongly affected by the dissolved ionic species from gangue minerals. In this study, the effect of calcium ions on the fluorapatite flotation using the extracted sodium alginate E.SA depressant was investigated through microflotation tests, adsorption experiments, zeta potential measurements, and FTIR analyses. Although the amount of NaOL collector adsorbed on fluorapatite increased with increasing calcium concentrations, microflotation results reveal that adding calcium ions could deteriorate the fluorapatite recovery. More significant depression of fluorapatite could be achieved when Ca2+ and E.SA co-existed in the system. Zeta potential measurements and FTIR analyses showed that the addition of Ca2+ hardly affected the adsorption of E.SA onto fluorapatite surface, which can be due to the formation and precipitation of calcium alginate. In contrast, NaOL remained weakly adsorbed on the fluorapatite surface even the presence of Ca2+ and E.SA. [ABSTRACT FROM AUTHOR]

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.

This paper proposes luteolin (LUT) as a novel depressant for the flotation-based separation of scheelite and calcite in a sodium oleate (NaOL) system. The suitability of LUT as a calcite depressant is confirmed through micro-flotation testing. At pH = 9, with LUT concentration of 50 mg·L−1 and NaOL concentration of 50 mg·L−1, scheelite recovery reaches 80.3%. Calcite, on the other hand, exhibits a recovery rate of 17.6%, indicating a significant difference in floatability between the two minerals. Subsequently, the surface modifications of scheelite and calcite following LUT treatment are characterized using adsorption capacity testing, Zeta potential analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The study investigates the selective depressant mechanism of LUT on calcite. Adsorption capacity testing and Zeta potential analysis demonstrate substantial absorption of LUT on the surface of calcite, impeding the further adsorption of sodium oleate, while its impact on scheelite is minimal. FT-IR and XPS analyses reveal the selective adsorption of LUT onto the surface of calcite, forming strong chemisorption bonds between the hydroxyl group and calcium ions present. AFM directly illustrates the distinct adsorption densities of LUT on the two mineral types. Consequently, LUT can effectively serve as a depressant for calcite, enabling the successful separation of scheelite and calcite. [ABSTRACT FROM AUTHOR]

The separation of chalcopyrite and pyite is not fully solved, and thus more efficient depressants are still needed in industry. This paper used potassium permanganate (KMnO4) as a pyrite depressant to separate pyrite from chalcopyrite. Flotation and contact angle results indicated that pyrite could be depressed by KMnO4 at pH 7, while KMnO4-treated chalcopyrite could be floated by sodium ethylxanthate. For the pyrite-chalcopyrite mixture, the recovery of chalcopyrite was nearly 95% and that of pyrite was less than 15% when minerals were reacted with 4 × 10−4 KMnO4 for 3 min. The KMnO4-treatment raised the zeta potential of pyrite at pH 7, which may generate oxidized species on the pyrite surface. The oxidation products on the pyrite surface were FeO, FeOOH, and Fe2(SO4)3 as determined by XPS analyses. These oxidation products were well coated on the pyrite surface, which dramatically lowers the hydrophobicity of pyrite. In contrast, in the case of chalcopyrite, KMnO4 treatment did not generate new oxidation components on its surface, causing the chalcopyrite surface to remain hydrophobic and allowing the flotation of chalcopyrite by air bubbles. Thus, pyrite could be efficiently separated from chalcopyrite using KMnO4 as a depressant. [ABSTRACT FROM AUTHOR]

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. [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]

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]

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.

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]

Diethylenetriaminepenta (methylene-phosphonic acid) pentasodium salt (DTPMPA), an ecofriendly reagent, was tried for the first time as a depressant for flotation separation of scheelite from calcite. Micro-flotation tests show that DTPMPA can selectively depress the floatability of calcite. In contrast, DTPMPA barely affects the flotation behavior of scheelite. Based on the selective depress effect, floatation separation of scheelite and calcite can be effectively achieved by using DTPMPA as depressant in artificially mixed minerals flotation tests. Based on a series of measurements, it found the surface of calcite was positively charged due to the existence of Ca ion site, which can be chelated with -PO3H-functional group on the surface of DTPMPA. In the flotation process, DTPMPA can be chemically absorbed on the surface of calcite to inhibit further collector adsorption. On contrast, little DTPMPA was adsorbed on the surface of scheelite due to the spatial site resistance and electrostatic repulsion induced by surface WO42+. All in all, these results exhibit DTPMPA has excellent selective depression ability on calcite, which can be potentially applied in the actual scheelite flotation process. [ABSTRACT FROM AUTHOR]

In this study, hydroxypropyltrimethyl ammonium chloride chitosan (HACC) was first introduced as a depressant during separating chalcopyrite from molybdenite (Cu-Mo). The selective effects of HACC on the separation of Cu-Mo were conducted by single-mineral flotation experiments. The findings from this study revealed that HACC helped separate Cu and Mo efficiently at pH 6 with 8 mg/dm3 of HACC, resulting in 76.22% and 5.38% of Mo and Cu flotation recovery, respectively. The adsorption mechanism of HACC was investigated via zeta potential, adsorption density, and contact angle measurement along with FT-IR and XPS analyses. The contact angle and adsorption density measurements offer indisputable proof that HACC can adsorb on the surface of chalcopyrite. Furthermore, FT-IR and XPS analyses confirm that N atoms in quaternary ammonium groups of HACC interact with Cu sites on the surface of chalcopyrite. The findings also suggest that HACC adsorbs on the surface without significantly impacting molybdenite. All these results confirm that HACC can be an effective chalcopyrite depressant. [ABSTRACT FROM AUTHOR]

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 Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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 Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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.)