Malachite Surface Research Articles

Surface modification of malachite with tetraamminecopper (II) and its effect on sulfidation flotation

In view of the strong hydrophilicity of malachite, the sulfidation performance of conventional sulphidizing reagent sodium sulfide on malachite is not satisfactory. In this work, we discussed the effect of tetraamminecopper (II) complex pretreatment on the sulfidation and flotation behavior of malachite. The performance was evaluated by micro-flotation experiments. The flotation results showed that a better flotation recovery can be obtained with a molar concentration of tetraamminecopper (II) sulfate of only one-twentieth of the conventional activator (NH4)2SO4, all else being equal. Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM-EDS) shows that the weight percentage of S and Cu on the surface of the sulfidized malachite increased significantly in the present of [Cu(NH3)4]2+. The FTIR and Raman results showed that sulfur ions could be chemisorbed on the surface of malachite and form a layer of copper-sulfide species. X-ray photoelectron spectroscopy (XPS) further confirmed the actual existence of the sulfide layer, which consists of monosulfide (S2−), disulfide(S22−) and polysulfide (Sn2−). The presence of the activator [Cu(NH3)4]2+ can significantly increase the formation of disulfide and polysulfide on the surface of malachite, thereby promoting the subsequent interfacial adsorption of xanthate.

Influence of ferrous ions on surface properties of malachite and its response to sulfidization xanthate flotation

Sulfidization flotation is the principal method used for recovering malachite. There are some unavoidable metal ions appear in the solution during enrichment, and the existence of ferrous ions has a certain impact on the surface sulfidization and xanthate adsorption on surface of malachite. In this work, the influence of the ferrous species on the sulfidization flotation of malachite were investigated, and it showed that the ferrous species could be adsorbed on the mineral surface before and after sulfidization. Meanwhile, the hydroxyl species increased due to the addition of ferrous ions adsorbed as Fe–hydroxyl species, and depressed the formation of S2– and Sn2–species. However, the SOn2–species with excessive oxidation increased significantly. The content of the Cu(I) species decreased, implying that the addition of ferrous ions was not conducive to the sulfidization process of malachite and the reactivity of sulfidization products with subsequent reagents decreased. In addition, the S and Fe species adsorption layer on malachite surface were visually characterised using time–of–flight secondary ion mass spectrometry analysis, and verifies the above experimental results. After ferrous ions was introduced into flotation system, the adsorption of collector decreased and the consumption of collector in solution increased. Therefore, the flotation recovery of malachite was reduced by the addition of ferrous ions before and after sulfidization.

Effect of Ammonium Sulfide on Sulfidization Flotation of Malachite

Recently, several studies have shown the positive effect of sulfidization flotation on malachite surfaces and its enhancing methods. Therefore, this paper was focused on the effect of ammonium sulfide and sodium sulfide on the sulfidization of malachite, respectively; this was investigated using different devices such as the micro-flotation tests, Zeta potential measurements, ToF–SIMS, XPS analysis, and FTIR. Thus, Fourier transform infrared spectroscopy results demonstrated that a new characteristic peak of Cu-S bonds was formed and adsorbed on malachite surfaces at 1694 cm−1, as confirmed by XPS analysis. Notably, malachite with ammonium sulfide ions had a significantly higher flotation recovery than malachite with an excess of sodium sulfide ions, as concerns of sulfidization types. Conclusively, all the experiments in this study confirmed that additional copper sulfide products were formed on the malachite surface, increasing the hydrophobicity of the malachite.

Biofabrication of ZnO/Malachite nanocomposite and its coating with chitosan to heal infectious wounds

Recently, nanocomposites produced from clays and metals coated with chitosan have shown wound healing activity. This study aimed to synthesize the zinc oxide/malachite nanocomposite (ZnO/Mlt-NC) and its coating form with chitosan (ZnO/Mlt/Chsn-NC). Physicochemical characterization of the produced nanocomposites was investigated. Biomedical effects of nanocomposites, such as in vivo and in vitro antibacterial activity, antioxidant properties, cytotoxicity, and modulation in the gene expressions of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), and transforming growth factor-β (TGF-β) and histopathological parameters, were also investigated. Expression intensities of basic fibroblast growth factor (bFGF) and tumor necrosis factor alpha (TNF-α) were also investigated by immunofluorescence staining. To investigate biomedical effects under in vivo conditions, infected wounds were induced and inoculated with Staphylococcus aureus (ATCC 25923), and Pseudomonas aeruginosa (ATCC 27853). The results indicated spherical ZnO nanoparticles on the surface of malachite and strong antibacterial activity and antioxidant properties. The ointments produced from the nanocomposites also exhibited wound healing activity. The administration of the ointments prepared from ZnO/Mlt, and ZnO/Mlt/Chsn NCs decreased the expressions of IL-1β, IL-6, and TNF-α, while it increased the expressions of IL-10, TGF-β and bFGF. In sum, the nanocomposites produced from ZnO, malachite, and chitosan had better biological activity than ZnO/Malachite nanocomposites. We suggest applying ZnO/Mlt/Chsn nanocomposites in the structure of ointments to treat infected wounds after future clinical studies.

Adsorption behavior and mechanism of copper ions in the sulfidization flotation of malachite

Malachite is one of the main minerals used for the industrial enrichment and recovery of copper oxide resources, and copper ions are unavoidable metal ions in the flotation pulp. The microflotation, contact angle, and adsorption experiments indicated that pretreatment with an appropriate concentration of copper ions could improve the malachite recovery, and the addition of excess copper ions reduced the hydrophobicity of the malachite surface. The results of zeta potential tests indicated that sodium sulfide and butyl xanthate were also adsorbed on the surface of malachite pretreated with copper ions. X-ray photoelectron spectroscopy (XPS) results indicated that —Cu—O and —Cu—OH bonds were formed on the surface of the samples. After pretreatment with an appropriate concentration of copper ions, the number of —OH groups on the mineral surface decreased, whereas the number of Cu—S groups on the mineral surface increased, which was conducive to the sulfidization of malachite. After adding a high concentration of copper ions, the —OH groups on the mineral surface increased, whereas the number of Cu—S groups decreased, which had an adverse effect on the sulfidization flotation of malachite. Time-of-flight secondary ion mass spectrometry showed that pretreatment with copper ions resulted in a thicker sulfidization layer on the mineral surface.

Uncovering the flotation performance and adsorption mechanism of a multifunctional thiocarbamate collector on malachite

In this paper, a novel collector N-octanoyl-S-carboxyethyl thiocarbamate (OCETC) containing CO, CS and -COOH groups was synthesized and applied to recover malachite. The flotation performance and adsorption mechanism of OCETC on malachite surface were systematically investigated by DFT calculation, zeta potential, FTIR, XPS, contact angle measurements and flotation experiments. It was found that CO, CS and -COOH groups were the functional sites which could react with Cu(II) ions on malachite surface and formed COCu(I) and CSCu(I) bonds. The adsorption of OCETC on malachite surface significantly improved its surface hydrophobicity since the contact angle of water on malachite changed from 46.5° to 78.0°. The flotation experiments demonstrated that 6 × 10−5 mol/L OCETC enabled the recovery of up to 98.24% malachite at pH 8.0. Under the same flotation conditions, OCETC exhibited comparable flotation recovery for malachite compared to octyl hydroxamic acid (98.43%), but much better than that by benzoyl hydroxamic acid (54.13%).

Adsorption mechanism and flotation behavior of ammonium salt of N-Nitroso-N-phenylhydroxyamine on malachite mineral

The adsorption mechanism between malachite and a specific organic ligand of the ammonium salt of N-Nitroso-N-phenylhydroxyamine (NBH) with the NH4+ group and nitrosamine polar group has been studied. The tapping mode atomic force microscopy (AFM) imaging illustrated that irregular protrusions were covered on malachite surface at the nanoscale when malachite was treated in NBH solutions under alkaline conditions at pH 9.5. It indicated that the NBH displayed an excellent affinity to malachite, and the adsorption density was correlated with the concentration of NBH. Based on copper ammine theory and the results of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the intermediate transition process of the interaction between malachite and NBH can be summarized as activation, diffusion and reduction, combination, and redeposition. The copper ions removed from the ammonia-activated malachite surface combined with the NBH resonating structures to form the bidentate and monodentate complexes. Eventually, those microscopic analyses are confirmed by the macroscopic flotation test. The flotation recovery illustrated the formation of ligand–Cu complex strengthened the hydrophobicity of malachite in a three-phase system. Therefore, it is feasible using NBH as collector to selectively separate malachite from gangue minerals in flotation experiments.

Study on degradation of Cambodian panel painting during UV aging

AbstractIn this research, the glue films, ground and paint layers were aged under UV‐C radiation. The glue films were prepared using tamarind gum and liang‐chey resin powders. The ground (calcium carbonate mixed with tamarind glue) and paint layers (red cinnabar, malachite, Prussian blue mixed with liang‐chey resin) were applied on the iron wood using traditional tempera technique. The degree of disintegration was determined using scanning electron microscopy with energy dispersive X‐ray instrumentation, thermogravimetric analysis, attenuated total reflectance Fourier transformed infrared spectroscopy and powder X‐ray diffraction. The tamarind film turned brown after 14 days. While, liang‐chey resin film did not show any significant color change. The thermogravimetric analysis showed the lower thermal stability of the aged tamarind film. The discoloration and cracking on the ground layer surface stemmed from the disintegration of tamarind binder. After 14‐day exposure, the color of red cinnabar changed from bright red to dark red with black spots all over the surface. These spots were identified by powder X‐ray diffraction measurements as β‐HgS (black). After prolonged UV exposure, the white solid was appeared on the cinnabar surface and identified as anhydrite (anhydrous CaSO4) and gypsum (CaSO4.2H2O). The yellow color appeared on the malachite surface might come from the discoloration of the tamarind glue binder in the ground layer. While the brown layer found on aged Prussian blue surface was confirmed as the mixture of β‐PbO2, Pb3O4, and β‐FeOOH.

Structural modification of hydroxamic acid collectors to enhance the flotation performance of malachite and associated mechanism

A series of N-hydroxy-N-aryl amide collectors, including N-hydroxy-N-benzyl acetamide (NHNBA), N-hydroxy-N-benzyl butyramide (NHNBB), N-hydroxy-N-phenyl acetamide (NHNPA) and N-hydroxy-N-phenyl butyramide (NHNPB), was designed in this study and employed for the first time in malachite flotation. Flotation tests conducted in the absence of frothers and activators revealed that the N-hydroxy-N-aryl amide collectors realized effective separation of malachite from calcite and quartz, which could not be readily achieved with benzohydroxamic acid (BHA). NHNBB exhibited optimal collection ability and selectivity for malachite over calcite and quartz. Quantum chemistry calculations, solution chemistry analysis and FTIR spectroscopy and XPS analyses revealed that in addition to electrostatic attraction, NHNBB possibly interacted with the malachite surface via chemisorption by forming five-membered-ring complexes, resulting in an efficient collection capacity for malachite.

Efficiently separating malachite from talc using new collector famciclovir via reverse flotation

In this study, famciclovir was used as a new collector in the flotation separation of malachite from talc. The results of flotation tests demonstrated that famciclovir had higher selective collection ability to talc than malachite. Famciclovir could remove talc from malachite-talc mixture, including −10 μm talc. The adsorption behaviors of famciclovir onto the surfaces of malachite and talc were researched by contact angle measurement, X-ray photoelectron spectroscopy (XPS) analysis and FTIR spectrum measurements, which indicated that famciclovir can selectively adsorbed onto talc surface. Thus, famciclovir could be used as a high-selectivity collector to efficiently separate malachite from talc and reduce the covering of talc slime on malachite surface. Therefore, famciclovir is expected to have great potential for pre-desliming in the flotation of copper oxide minerals.

Selective collection performance of an efficient quartz collector and its response to flotation separation of malachite from quartz

In this study, laurylamine ethoxylate with fifteen ethoxylate units (LAEO-15) was employed as a quartz collector for the recovery of malachite from quartz via reverse flotation. Its collecting performance and adsorption mechanism were evaluated by flotation tests and surface analyses. The results of flotation tests suggested that LAEO-15 had an intense ability to collect quartz instead of malachite, and displayed a high flotation selectivity, which promoted the significant floatability differences of both minerals. XPS confirmed that quartz adsorbed a much larger quantity of LAEO-15 than malachite, resulting in the selective collection of quartz with LAEO-15. Zeta potential and FTIR characterization further uncovered that the strong adsorption of LAEO-15 was driven by hydrogen bonding and electrostatic attraction, while electrostatic repulsion hindered the LAEO-15 adsorption on the surface of malachite. As a result, the effective separation of malachite and quartz was realized with 20 mg/L LAEO-15 at pH 6.30 via reverse flotation, in which 92.54% of malachite was recovered and 92.72% of quartz was removed, coupled with a high SI value of 12.57 in concentrate. Therefore, compared with conventional collector dodecylamine, LAEO-15 exhibited high selectivity and purification effectiveness for the separation of malachite from quartz.

DFT and TOF-SIMS study of the interaction between hydrogen sulfide ion and malachite (–201) surface

DFT and TOF-SIMS study of the interaction between hydrogen sulfide ion and malachite (–201) surface

Adsorption of cupferron on malachite (−2 0 1) surface and implication for flotation

This paper investigated the adsorption mechanism of cupferron on the malachite (−201) surface and the implications for flotation via X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) measurements, density functional theory (DFT) calculations, and microflotation tests. The XPS and FTIR analyses confirmed the adsorption of cupferron on the malachite surface. The DFT calculations indicated that the adsorption was mainly due to the reaction between O atoms in cupferron and Cu atoms on the malachite surface. Six different adsorption configurations were discussed, and the Cu3-cupferron anion-O1O2 model was the most stable. The five-membered-ring cupferron-Cu complex was produced under this condition, and the corresponding adsorption energy is −2.092 eV. The density of states (DOS) analysis reveals that the O 2p orbital from cupferron O atoms and the Cu 3d orbital from malachite Cu atom overlapped at −0.7 to 0.3 eV and −2.6 to −0.8 eV around the Fermi level, demonstrating a stable chemical adsorption. The population analysis showed that electron transfer occurred between the Cu and O atoms during the adsorption process. The micro-flotation results showed that cupferron has a strong collecting performance for malachite. This research provides a better understanding of the adsorption mechanism of cupferron on malachite surfaces at the atomic level. It is of great significance for its application in flotation.

Effectiveness of bacterial sulfidation flotation for the separation of malachite: Impact of pH, sulfide concentration and sulfidation time

Previous research paid less attention on the mechanism and application of bacterial sulfidation in mineral flotation. In this study, sulfate reducing bacteria strains reduce sulfate to produce sulfides, which are used as sulfidizing reagents for malachite. Then, the system influence factors such as pH, sulfides concentration and sulfidation time are controlled. The results showed that the most suitable conditions of malachite bacterial sulfidation system were pH of 9.0, sulfide concentration of 140mg/L and sulfidation time of 15mins. For further study, SEM and FTIR were used to perform of sulfide film formed on the surface of malachite. The result of sulfide film on the malachite surface is compact, and the malachite flotation properties are greatly improved after bacterial sulfidation.

The effect and mechanism of cinnamic hydroxamic acid as a collector in flotation separation of malachite and calcite

This study presents the use of Cinnamic Hydroxamic Acid (CHA) as a novel collector of malachite. The flotation performance was evaluated by microflotation experiments. The mechanism of CHA adsorption at malachite surfaces was studied by contact angle measurements, zeta potential measurements, infrared spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). The microflotation experiments demonstrated that the CHA improved selectivity in comparison to benzohydroxamic acid (BA) during malachite flotation. Artificial mixed mineral flotation experiments verified that malachite could be separated from calcite effectively with the CHA collector. The results from contact angle measurements indicated that the hydrophobicity of the malachite surface was increased after CHA treatment. Zeta potential and infrared spectroscopy measurements implied that the adsorption of CHA at malachite. XPS analysis demonstrated that the C and N concentration on the malachite surface increased, with a concomitant decrease in Cu concentration.

Modification of malachite surfaces with lead ions and its contribution to the sulfidization flotation

Malachite is a common copper-oxide resource, and it is usually enriched by sulfidization flotation. Its floatability and recovery are greatly determined by the surface sulfidization results. In this paper, Pb(NO3)2 is used to pretreat malachite, and the sulfidization mechanism of malachite was studied through microflotation experiments, zeta-potential determination, adsorption tests, XPS and ToF-SIMS. The flotation and adsorption results show that the malachite floatability after pretreatment with Pb ions improved significantly. Compared with Na2S treatment, the maximum recovery increased by 42.6% after treatment with lead ions and Na2S. The zeta potential results showed that lead ions (such as Pb(OH)+) could adsorb on the malachite surface, and the surface active sites of malachite were increased. XPS results indicate that lead ions adsorbed onto the mineral surface through the interaction between Pb species, S species and O species. The formation for new species (such as Pb-S) enhanced the malachite sulfidization. ToF-SIMS was used to visualize the three-dimensional distribution of lead- and sulfur-species adsorbed on the malachite surface. It demonstrated that the sulfidization layer increased after pretreatment with Pb(NO3)2, facilitating the surface hydrophobicity and flotation recovery of malachite.

Adsorption characteristics of Pb(II) species on the sulfidized malachite surface and its response to flotation

Sulfidization flotation is the main method for recovering non-ferrous metals oxide minerals, and the sulfidization effect determines the flotation recovery of minerals. In this paper, the effect of Pb(II) on the flotation of malachite sulfidized with sodium sulfide was studied through microflotation experiments, zeta-potential determination, adsorption experiments, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The microflotation experiments revealed that the floatability of sulfidized malachite was increased after treatment with Pb(II), with the maximum flotation recovery reaching 89.8% under the experimental conditions. The zeta-potential measurements showed that Pb(II) species can adsorb on the sulfidized malachite surface, increased the active sites on the mineral surface, and promoted the adsorption of the collector. XPS analysis indicated that addition of Pb(II) changed the chemical environment of the sulfidized malachite surface, and the formation of Pb species (Pb–S) and S species (S2− and Sn2−) enhanced the sulfidization of malachite surfaces. ToF-SIMS surface and depth profile analysis were used to intuitively explore the adsorption of the reagents, and they confirmed the positive effect of Pb(II) on malachite sulfidization. These results illustrated that the adsorption of Pb(II) on the sulfidized malachite surface was conducive to its flotation recovery.

Flotation Behavior and Synergistic Mechanism of Benzohydroxamic Acid and Sodium Butyl-Xanthate as Combined Collectors for Malachite Beneficiation

Sulfuration flotation is the most widely used technology in malachite beneficiation. However, the inhomogeneity of malachite surfaces usually results in a non-uniform sulfuration surface. The motivation of this work is attempt to adopt different functional combination collectors to enhance the sulfuration flotation of malachite. Accordingly, the flotation behaviors and adsorption mechanisms of benzohydroxamic acid (BHA) and sodium butyl-xanthate (SBX) on the surface of malachite were systematically investigated using flotation tests, zeta-potential measurements, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and first-principle calculations. The test results of vulcanization flotation showed that the combined collectors of SBX with BHA possessed a higher recovery than only using SBH by 20%, indicating that there may be a synergistic effect between BHA and SBX. The IR and Raman spectroscopy demonstrated that both BHA and SBX could chemically adsorb onto the malachite surface. The density functional theory (DFT) calculation results further indicated that the combined adsorption energy of BHA and SBX was much lower than that of only BHA or SBX, which confirmed the synergistic effects of BHA and SBX on the malachite surface. This work may shed new light on the design and development of more efficient combined flotation reagents.

Synthesis of 1-(2-Hydroxyphenyl) Dec-2-en-1-One Oxime and Its Flotation and Adsorption Behavior for Malachite.

A novel collector of 1-(2-hydroxyphenyl) dec-2-en-1-one oxime (HPDO) was synthesized from 2-hydroxy acetophenone and octanal, and its flotation and adsorption behavior for malachite were studied by flotation tests and x-ray photoelectron spectroscopy (XPS) analysis. The flotation results of a single mineral show HPDO is a special collector for malachite. Compared with benzohydroxamic acid (BHA), isobutyl xanthate (SIBX), and dodecylamine (DA), HPDO exhibits excellent flotation performance for malachite and satisfied selectivity against quartz and calcite over a wide pH range. The HPDO with a concentration of 200 mg/L can float 94% malachite at pH 8, while only recovering 7.8% quartz and 28% calcite. XPS data give clear evidence for the formation of a Cu-oxime complex on malachite surfaces after HPDO adsorption.

Flotation performance and adsorption mechanism of novel 1-(2-hydroxyphenyl)hex-2-en-1-one oxime flotation collector to malachite

Abstract A novel collector 1-(2-hydroxyphenyl)hex-2-en-1-one oxime (HPHO) was synthesized from 2-hydroxy acetophenone and butyraldehyde. Its flotation performance and adsorption mechanism to malachite were investigated by flotation test, zeta potential, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis techniques. Compared with benzohydroxamic acid (BA), 1-(2-hydroxyphenyl)ethan-1-one oxime (HPEO) and sodium isobutyl xanthate (SIBX), HPHO exhibited excellent collecting power to malachite without additional reagents, such as Na2S regulator and methyl isobutyl carbinol (MIBC) frother. Results of zeta potential indicated that HPHO was coated on malachite surfaces through a chemisorption process. FTIR and XPS data gave clear evidence for the formation of Cu–oxime complex on malachite surfaces after HPHO adsorption through the linkage between C=C, –OH, N–OH group and Cu species.