Malachite Surface Research Articles

Improved activation of malachite sulfurization flotation by thiourea's (CS(NH2)2): Performance and mechanism study

In this study, thiourea (CS(NH2)2) was an effective activator for promoting the sulfurization flotation of malachite. The flotation behavior of malachite in the presence of this activator was investigated. Experimental results revealed that thiourea is a superior activator for malachite sulfurization, achieving a recovery rate of over 89 % at appropriate dosages. Thiourea-sulfurized malachite forms a surface layer of copper(I) thiocyanate, which facilitates the reduction of Cu(II) to Cu(I) species, leading to the generation of more Cu(I)−S species. These species adsorb more readily onto the malachite surface compared to Cu(II)−S species. The robust layers consist of SCN¯ ligands that combine with copper(I) complexes to form CuSCN species during sulfurization. This enhances malachite surface sulfurization, resulting in higher flotation recovery. Further analysis using ToF−SIMS, FESEM−EDS, and XPS confirmed that thiourea likely chemisorbs onto the malachite surface through sulfurized malachite. The activation mechanisms and the presence of N-atoms in the XPS spectra verified that N−H, C−N, and Cu−N bonds were chemisorbed and formed on the surface, significantly improving the hydrophobicity of sulfurized malachite. This work has important implications for the future application of thiourea activation in flotation processes and could contribute to developing environmentally friendly solutions to meet consumer demand.

Understanding the Adsorption Mechanism of BTPA, DEPA, and DPPA in the Separation of Malachite from Calcite and Quartz: DFT and Experimental Studies

The relationship between the structure of bis (2,4,4-trimethylpentyl) phosphinic acid (BTPA), diethyl phosphinic acid (DEPA), and diphenyl phosphinic acid (DPPA) on the flotation performance of malachite was investigated. Through a series of flotation experiments, density functional theory (DFT) calculations, and surface analysis methods, we aimed to deeply understand the microscopic mechanism of the interactions between these collectors and the malachite surface. The experimental results showed that BTPA exhibited excellent selectivity and flotation performance for malachite in the pH range of 5.0–11.0, significantly better than DEPA and DPPA. Surface analysis evidence from X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) further confirmed the chemical adsorption characteristics of BTPA on the malachite surface. DFT calculations revealed that the adsorption capacity of BTPA on the malachite surface exceeds that of DEPA and DPPA. Electron transfer analysis, especially through frontier molecular orbital theory, differential charge density, PDOS, and COHP analysis, indicated that the charge transfer process from the s orbitals of oxygen atoms in the collectors to the d orbitals of copper atoms on the mineral surface is the decisive factor for the adsorption strength.

Evolution of sulfur species on malachite surfaces in the presence of calcium and magnesium ions and implications for xanthate flotation

The depletion of mining resources has led to a sharp increase in gangue minerals. The use of flotation technology with seawater, which is rich in Ca2+ and Mg2+, has gradually increased. However, these ions may affect the flotation process. Herein, we study the effects of the addition of Ca2+ and Mg2+ on the process and products of malachite sulfidization. Analysis of the S layer on the mineral surface indicates that the quantities of S components generated on the malachite surface decrease in the presence of Ca2+ and Mg2+. Additionally, Ca2+ and Mg2+ induce the excessive generation of oxidized S species (SOn2−) during sulfidization, which inhibits the formation of Cu2S. Furthermore, both the solubility of malachite and the consumption of collector ions in the solution increase in the presence of Ca2+ and Mg2+. Microflotation experiments confirm that Ca2+ and Mg2+ result in insufficient sulfidization properties on the malachite surface and reductions in the activity of the sulfidization products, leading to a decrease in sample floatability.

N1,N10-dihydroxydecanediamide: Its separation performance and action mechanism for malachite, calcite and quartz

In this study, a novel collector, N1,N10-dihydroxydecanediamide (DHH) was synthesized in our lab and introduced in flotation of malachite ore. The separation performance and action mechanism of DHH were explored and compared with octyl hydroxamic acid (OHA). The results of single mineral flotation tests indicated that DHH exhibited a stronger collecting ability to malachite and better selectivity against quartz and calcite than OHA, and floated out 94 % malachite, 8.5 % quartz and 17 % calcite at pH = 10 with a collector concentration of 60 mg/L. The FTIR spectra, zeta-potential tests and XPS tests proved that DHH could absorb onto malachite surface though a chemical mode. DFT calculation results showed that DHH anion owned a stronger affinity to malachite than DHH molecular and OHA anion/molecular, and its bis-minerophilic groups could form C(=O)NHO-Cu bond with surface Cu atom. It exhibited that DHH was an excellent candidate and capable for high efficiency flotation of malachite ore.

Flotation activation mechanism of trithiocyanuric acid to malachite

Malachite is a typical refractory copper oxide mineral. In this paper, trithiocyanuric acid (TMT) was used as a novel activator for the activated flotation of malachite for the first time. The effect of TMT on the flotation behavior of malachite was studied and the activation mechanism was discussed. The flotation test results showed that TMT exhibited superior activation performance over sodium sulfide, achieving a high flotation recovery rate of 97.50 % at TMT 90 mg/L and pH 7. The contact angle confirmed malachite improved from 53.3° to 90.1° after TMT treatment, indicating enhanced hydrophobicity of the mineral surface. FTIR and EDS analyses provided clear evidence of chemical adsorption of TMT tautomers onto the malachite surface. SEM images further illustrated the presence of dense particles formed after TMT treatment. XPS revealed that TMT exhibited a strong adsorption effect on malachite, leading to an increase in copper sites and the formation of highly reactive Cu+. The activation mechanism was elucidated as the reaction between Cu sites on malachite and S and N atoms in TMT, forming Cu-S and Cu–N fractions crucial for activation. The high efficiency and low dosage of TMT make it a promising activator for malachite, offering a novel avenue for the effective recovery of malachite-type copper oxide ore resources.

New Insights into the Role of Thiol Collectors in Malachite Flotation

Malachite is one of the most important copper-bearing oxide minerals; however, it shows poor floatability prior to sulfidization under the thiol collector system. This study investigated the reasons for the low recovery of malachite flotation without sulfidization. The results of adsorption capacity and contact angle test indicated that the malachite surface could adsorb a sufficient amount of the collector, obviously increasing the hydrophobicity of the malachite surface under static conditions. By measuring the amount of inorganic carbon in the flotation solution, it was found that the amount of inorganic carbon in the solution increased significantly when the thiol collectors were added into pulp, which could be attributed to the induced dissolution of the malachite surface by thiol collectors. Solubility tests further demonstrated that the copper ions released from the natural dissolution of malachite proved difficult in regard to reactions with thiol collector to form precipitates; however, the thiol collector induced the dissolution of malachite surface, and so the hydrophobic complexes’ copper-collector could not firmly adsorb on the mineral surface. Fourier transform infrared (FTIR) analysis revealed that thiol collectors do not adsorb stably on malachite surfaces. This was considered to be a substantial reason for the poor performance of malachite flotation without sulfidization.

Experimental and DFT study of modified malachite with 2,5-dimercapto-1,3,4-thiadiazole and its response to sulfidization-xanthate behavior

Malachite is industrially recovered using sulfidization–xanthate flotation. However, due to the instability of the sulfidization effect, it is necessary to strengthen the sulfidization process. To this end, a 2,5-dimercapto-1,3,4-thiadiazole (DMTD) can modify the malachite surface for enhanced sulfidization. Analysis of the sulfidization products indicated that more of highly active Cu2S(Cu(I))species and polysulfides (Sn2−) were found, indicating that the DMTD-modified malachite surface facilitated the adsorption of S components and improved the surface reactivity. Analysis of the sulfidized surface revealed that DMTD and Na2S together increased the ionic strength of S, further confirming that the DMTD-modified malachite surface facilitates S adsorption. Density Functional Theory (DFT) simulates implicate that the intensified sulfidization of malachite surface is due to the resultant of Cu-S products with various degrees of binding and enhanced interactions between S and Cu atoms. Analysis of the sulfidization efficiency of malachite surface confirmed that the DMTD-modified surface adsorbed additional -S components. Changes in the surface potential and contact angle of malachite suggested that the DMTD-modified surface was higher hydrophobic owing to strong adsorption of xanthate. Flotation experiments confirmed that DMTD can improve the sulfidization-xanthate floatability.

Synthesis and application of dithiocarbamate oxadiazole thione for flotation separation of malachite from quartz and calcite

In this paper, 5-methyl hexyldithiocarbamate-1,3,4-oxadiazole-2-thione (MHCODT) was synthesized for the first time and introduced as a flotation collector in malachite flotation separation process from quartz and calcite. During the micro-flotation experiment, it was found that MHCODT showed stronger flotation ability and selectivity for malachite than conventional collector octyl hydroxamic acid (OHA), and achieved effective separation and enrichment of malachite. Measurements of contact angles, ζ-potentials and UV spectra demonstrated that MHCODT specifically adhered to the surface of malachite rather than quartz and calcite. Then, FTIR and X-ray photoelectron spectroscopy (XPS) demonstrated that Cu of malachite surface combined with S and N of MHCODT to form MHCODT-Cu(I) complexes, accompanied by the reduction of divalent Cu. The result of density functional theory (DFT) method indicated that the CS bonds and NH bonds in oxadiazole thione and the dithiocarbamate groups were the chemical reaction center. Based on the above test results, the adsorption models of MHCODT-Cu+ and MHCODT-Cu2+ were proposed.

Flotation separation mechanism of malachite from calcite using the pentyl xanthate as the collector

Calcite is a commonly associated gangue mineral in oxidized copper ore, while the flotation separation of oxidized copper ore from calcite is a bottleneck technology in the utilization of carbonate-type oxidized copper ore. The present study applied the pentyl xanthate (PX) as a collector to efficiently separate malachite and calcite without any other reagents. The flotation results indicate that the PX dosage is a key factor determining the flotation separation results of malachite and calcite. When its dosage reaches 1000 mg/L, the flotation recovery rate of malachite can reach 88.7 %, while calcite is less than 5 %. The flotation test of real ore contained these two minerals further confirmed that the malachite could be separated from calcite using PX as the collector. The mechanism and characterization analysis show that the selective substitution reaction between xanthate ions and OH ions on the malachite surface could generate hydrophobic substances of copper xanthate, which largely improves the hydrophobicity of the malachite surface. This study is expected to provide theoretical and practical assistance for the efficient flotation beneficiation of low-grade marble-type copper oxide ore.

Interface adsorption mechanism of 5-nonyl salicylaldehyde oxime on malachite surface and its flotation separation performance with calcite and quartz

In this study, 5-nonyl salicylaldoxime (5-NSA) was synthesized and used as a malachite collector. Its flotation performances and adsorption mechanism were systematically investigated by micro-flotation experiments, contact angle measurements, SEM-EDS, FT-IR, XPS and DFTB+ simulations. The micro-flotation test results showed that 5-NSA produced high recovery of malachite at pH 9.0–10.0, while showing lower collecting power to calcite or quartz. The contact angle analysis results indicated that the hydrophobicity of malachite surface was promoted after the adsorption of 5-NSA. SEM confirmed the adsorption of 5-NSA on malachite surface. FT-IR and XPS analysis results confirmed that O and N atoms in the oxime group were immobilized on malachite surface with Cu through OCuO and NCuO bonding. Their adsorption performances on malachite surface were simulated by DFTB+ method, including 5-NSA, tert-butylsalicylaldehyde oxime (TBSA) and salicylaldoxime agents, which analyzed the bond lengths of their covalent bond formation with Cu and speculated their adsorption properties. In general, according to the experimental test and simulation results, 5-NSA showed a stronger power to malachite than TBSA and salicylaldoxime, and only a small dosage can produce a high malachite recovery. The findings of this research will be helpful to improve the comprehensive utilization efficiency of malachite and promote the metallurgy of copper oxide ores.

New insights into the activation mechanism of ammonium ions on the malachite sulfidization flotation

Ammonium sulfate [(NH4)2SO4] is an effective activator of malachite sulfidization flotation. In this work, we explored the effects of ammonium ion (NH4+) and copper ion (Cu2+) on malachite sulfidization flotation and investigated the underlying mechanism. Flotation experiments demonstrated that NH4+ can not only eliminate the negative effects of Cu2+, but also work together with Cu2+ to further promote malachite sulfidization flotation in a certain concentration range. Zeta potential, SEM-EDS, and X-ray photoelectron spectroscopy analysis results indicated that the single Cu2+ weakened the oxidation of S (II) species on the malachite surface and reduced the formation of sulfides. In the presence of NH4+, Cu2+ did not inhibit the formation of sulfides on malachite surface but worked with NH4+ to promote it. Aqueous speciation calculation and adsorption test revealed that NH4+ and Cu2+ interacted to form Cu (II)–NH3 complexes, which reacts with S (II) species to form a copper sulfide substance that is more easily adsorbed on the malachite surface than the copper sulfide colloid formed by the reaction between Cu2+ and S (II) species. This leads to the improvement of surface sulfidization.

Surface modification of malachite using DMTD and its effect on xanthate adsorption

Malachite is a representative copper oxide mineral, and its direct flotation using the xanthate method is challenging in industrial settings. Therefore, the selection of activators becomes pivotal for malachite enrichment. One such activator is 2,5-Dimercapto-1,3,4-thiadiazole (DMTD), a chelating agent capable of enhancing mineral surface activity through interaction. This property makes DMTD applicable in industrial production, although its mechanism of action remains unclear. This study delves into the activation mechanism responsible for surface modification of malachite using DMTD. DMTD, owing to its superior activation properties compared to Na2S, proves to be more effective in enhancing copper recovery in practical production scenarios. Consequently, the flotation of malachite treated with DMTD significantly improved under identical flotation conditions. Zeta potential experiments corroborated these findings, revealing that the surface modification of malachite using DMTD promotes greater adsorption of butyl xanthate (BX). The Fourier transform infrared spectroscopy (FTIR) results clearly demonstrated the chemical absorption of DMTD onto the malachite surface. Subsequently, the X-ray photoelectron spectroscopy (XPS) analysis unveiled the formation of a hydrophobic and stable copper-sulfide species on the malachite surface. Furthermore, time of flight secondary ion mass spectrometry (ToF-SIMS) analysis indicated that DMTD exhibits strong adsorption onto malachite, leading to the generation of CuS- and CuCN- species. Atomic force microscopy (AFM) analysis showed that DMTD predominantly adsorbed onto the malachite surface in a punctate pattern, displaying a uniform distribution across the entire surface. This finding was further validated by the contact-angle test, which confirmed that DMTD-treated malachite exhibited a more hydrophobic interaction with BX compared to untreated malachite. Consequently, the surface modification of malachite using DMTD was found to have a positive impact on BX adsorption, rendering it more hydrophobic.

Microscale exploration of the sulfidization flotation theory in malachite

With the gradual depletion of copper sulfide resources, efficient flotation technologies for the recovery of copper oxide minerals, such as malachite, have received significant attention. Although sulfidization plays a critical role in malachite flotation, the fundamental theory of sulfidization flotation remains uncertain in the context of practical industrial applications. In this study, evolution of the sulfide product morphology on the malachite surface was observed after treatment with various concentrations of sodium sulfide. In addition, the valence states and phase compositions of the sulfide products were investigated using different X-ray techniques. Furthermore, the evolution of the malachite surface morphology after the formation of a sulfide film was investigated, as were the interaction forces between the malachite and bubbles under the action of butyl xanthate. As a result, it was possible to directly observe the growth process of the sulfide film on the malachite surface, and the presence of Cu(I) was confirmed in the sulfide products. Moreover, the compositions of the sulfide products were investigated using X-ray techniques. The obtained results demonstrated that the sulfide film facilitated the formation of butyl xanthate product layers on the malachite surface, whilst also enhancing the interfacial interaction forces between the malachite and the bubbles.

Surface activation of malachite by ammonium acetate for improved flotation separation of malachite from calcite

Flotation separation of malachite from calcite is hampered by the surface homogenization of the two mineral surfaces. Therefore, in this study, ammonium acetate (CH3COONH4) was used to improve the flotation separation of malachite from calcite. The results of micro-flotation experiments revealed that, in the presence of CH3COONH4, the recoveries of malachite and calcite were, respectively, 85.91 % and 23.73 %, which was an improvement over the experiment conducted without CH3COONH4. Analyses of the surface morphology showed that CH3COONH4 prevented the adsorption of Cu–S on calcite, leading to a significant decrease in the calcite surface roughness. CH3COONH4 also prevented the oxidation of sulfides, which facilitated the formation of highly crystalline Cu–S on malachite. Additionally, CH3COO− prevented the formation of a dense sulfide layer on calcite. The adsorption of HS− on the surface of malachite was more energetically advantageous with NH3 than without NH3. In addition, adsorbed CH3COO− sterically hindered the adsorption of Cu–S on the O site of calcite. Bonding between the carboxyl group and Cu–S adsorbed decreased calcite activation. Therefore, CH3COONH4 catalyzed the sulfidation of malachite and inhibited calcite activation by adsorbed Cu–S, leading to improved flotation separation of malachite from calcite.

Selective modification of malachite with ammonium carbamate to promote flotation separation from calcite

The malachite and calcite surfaces treated with CH6N2O2 and Na2S·9H2O featured a flotation recovery rates of 82.51% and ∼ 20%, respectively, and achieved a satisfactory selective flotation separation of malachite from calcite. CH6N2O2 could promote the formation of Cu-S on the malachite surface. A large number of Cu-S on the malachite surface resulted in increased surface roughness. However, the calcite surface remained unchanged, and S elements were not detected on its surface. CH6N2O2 could facilitate the reduction of Cu(II) on the malachite surface to Cu(I) but impeded sulfide oxidation reactions, resulting in the formation of CuS2 with higher crystallinity. The hydrated malachite surface hindered the adsorption of HS−. The activation energy of catalytic sulfidation of malachite was higher than that of direct sulfidation, indicating that NH3 can enhance the adsorption of HS−. The Cu-S chemical bond formed through the catalytic sulfidation of malachite was stronger than that formed through direct sulfidation.

Contribution of ammonia in xanthates adsorption onto copper oxide mineral surface in high-alkaline solution

Ammonia is a useful modifier for enhancing surface sulfurization in copper oxide ore flotation using xanthate as a collector. However, its potential role in the reaction of sulfhydryl collector with sulfurized copper oxide mineral in a complex pulp has been neglected. This work investigates the contribution of ammonia to xanthate adsorption on the sulfurized malachite surface, independent of its effect on sulfurization. Zeta potential measurements indicate that NH3·H2O increases the surface potential of malachite and enhances the proximity of xanthate to the malachite surface in a strong-alkaline solution. Adsorption tests and time-of-flight secondary ion mass spectrometry analysis demonstrate that NH3·H2O can increase the xanthate adsorption density. Spectroscopic analysis reveals copper(I) xanthate and dixanthogen as the primary xanthate products, with their quantities increasing upon NH3·H2O treatment. Thermodynamic analysis of the reaction of malachite, HS−, and xanthate to form copper(I) xanthate and dixanthogen shows that NH3·H2O treatment enhances the stability of the reaction compared to its absence. Thus, NH3·H2O treatment increased the recovery of sulfurized malachite by over 10%. This study offers a comprehensive understanding of ammonia modification for enhancing sulfurization–xanthate flotation of copper oxide minerals and provides a scientific basis for developing high-efficiency collectors.

Surface characteristic and sulfidization-xanthate flotation behaviours of malachite as influenced by ferric ions

During the sulfidization–xanthate flotation of malachite in industrial production, Fe3+ in the pulp may affect mineral enrichment. In this study, we examined the adsorption of Fe3+ on the malachite surface and sulfidized surface to investigate the effect of Fe3+ on malachite sulfidization, sulfidization products, and mineral floatability. The results of experiments indicated that Fe3+ formed an adsorption layer on the samples surface and sulfidized samples surface, and adsorption of Fe–hydroxyl species led to hydroxylation of the samples. The proportion of Cu (I) species decreased during sulfidization, which indicated that the existence of Fe3+ had a negative effect on the sulfidization of the sample. Sulfidization products were identified, which revealed that the proportion of SO2–n increased significantly after treatment with Fe3+, suggesting that the reaction activity of the sulfidized surface was reduced. Moreover, the hydrophobicity of the mineral surface reduced after interaction with Fe3+ species, and led to reduced flotation recovery.

Role of ammonium phosphate in improving the physical characteristics of malachite sulfidation flotation

In this study, ammonium phosphate ((NH<sub>4</sub>)<sub>3</sub>PO<sub>4</sub>) was employed to realize improvement by modifying the physical characteristics of the malachite surface, ensuring sustainable flotation throughout the flotation operations, and enhancing the flotation process to be more stable. Furthermore, various techniques, including X−ray photoelectron spectroscopy, were intensely used to investigate the configuration and physico-chemical surface characteristics through micro-flotation experiments, contact angle and zeta potential measurements, and XRD, ToF−SIMS, EPMA, and FTIR spectrum analyses. The FTIR findings showed that new characteristic peaks of −C(=S)−N.H. groups formed and adsorbed on the surfaces of malachite at 1636 cm<sup>-1</sup>. The −CH<sub>2</sub> groups throughout the flotation process, further promoted the attachment of the CH<sub>3</sub> ligand to the Cu<sup>2+</sup> ion, and the XPS analysis confirmed this. Consequently, it can be concluded that (NH<sub>4</sub>)<sub>3</sub>PO<sub>4</sub> played a substantial part in the improved recovery rate, as demonstrated and confirmed by the methods carried out in this study. Thus, it was used to modify the physical properties surface before adding Na<sub>2</sub>S to efficiently enhance malachite floatability and reduce the loss rate of malachite. Regarding the alterations in the physical characteristics which occurred to the malachite surface, and as a consequence of increasing the recovery results of flotation, the malachite sample treated initially with (NH<sub>4</sub>)<sub>3</sub>PO<sub>4</sub> exhibited micro flotation results with a considerably greater flotation recovery than malachite treated initially with only Na<sub>2</sub>S ions.

A novel method for improving sulfidization xanthate flotation of malachite: Copper–ammonium synergistic activation

Malachite, as an important copper oxide mineral, is mainly separated and recovered from ores using sulfidization xanthate flotation method. In this paper, copper ions and ammonium salts were used as activators to modify the malachite surface, which improved its reactivity and improved the sulfidization and hydrophobicity of the mineral surface. Micro-flotation test results show that the flotation recovery of malachite can be greatly improved by this synergistic activation system, compared with that upon treatment in a direct sulfidization system. Zeta potential, XPS and ToF-SIMS analysis showed that the content of highly active cuprous sulfide species and copper sites on the malachite surface increased after the copper–ammonium synergistic activation treatment. FTIR characterization and contact angle measurement indicated that more xanthate components were stably adsorbed on the malachite mineral surface after the synergistic activation of the copper–ammonium, thereby increasing the hydrophobicity of the surface. Therefore, the synergistic activation not only resulted in the enhanced sulfidization of malachite surfaces, but also enhanced the reactivity and hydrophobicity of malachite surfaces, thus promoting the hydrophobic flotation of malachite. This represents a new concept and process for the efficient flotation recovery of oxidized copper minerals.

Evaluation of L-arginine as an Eco-Friendly Activator for Malachite Sulfidization Flotation

Sulfidization xanthate flotation remains the most promising method for the beneficiation of malachite. In this study, L-arginine (LA) was first used to modify the malachite surface and improve the efficiency of sulfidization flotation. The performance of LA was evaluated by the flotation experiments. The mechanism of interaction between LA and the malachite surface was investigated by adsorption experiments, zeta potential measurements, scanning electron microscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis. Flotation experiments showed that LA had a significantly promoting effect on malachite sulfidization flotation. Adsorption experiments and SEM-EDS results indicated that LA improved the adsorption of S (II) species into the malachite surface and promoted the formation of sulfides. This finding was further confirmed by the XPS analysis. The XPS measurements results determined that S (II) species reacted with Cu (II) on the malachite surface and form polysulfides, adding LA promoted the reaction. The zeta potential measurements showed that LA increased the positive electrical properties of the mineral surface, which was conducive to S (II) species adsorption and the sulfidization reaction. This work sheds new light on the development of sulfidization activation.