Surface Properties Of Minerals Research Articles

Effects of surfactant with different injection times on asphaltene adsorption behaviors on the kaolinite surfaces: A molecular simulation study

The adsorption behavior of asphaltenes on the mineral surfaces seriously reduces oil recovery, which is dependent on the molecular structure, surface properties of the inorganic minerals, and the injection time of chemicals. In the present study, the molecular dynamics (MD) simulation is performed to construct the asphaltene-kaolinite adsorption systems and the 3-(N,N-Dimethyloctadecylammonio) propane sulfonate (DOPS) surfactant flooding systems to explore the effect of DOPS injection times on the detachment of asphaltene aggregates with discrepant adsorption characteristics. The number density distribution and the interaction analysis between asphaltene and kaolinite are employed to evaluate the adsorption behaviors of asphaltene on the kaolinite-liquid interfaces. The radial distribution function (RDF) describes the relative positions of the surfactants and asphaltene aggregates. The effective free energy and the independent gradient model based on Hirshfeld partition (IGMH) method further illustrate the microscopic mechanism of asphaltene detaching by the surfactant. The simulation results indicate that intensely polar carboxylate groups and polyaromatic rings with π-conjugated structures dominate the adsorption behavior of asphaltenes. The DOPS surfactants injected after the water flooding are difficult to produce effective ways of detaching asphaltenes, while the introduced DOPS surfactants during water flooding can generate DOPS-ASPn combinations to detach asphaltene from the kaolinite surfaces. This work first investigates the effects of surfactants with different injection times on the oil detachment efficiency at a molecular scale, further deepening the understanding of oil detachment process via surfactant flooding.

Chitosan as an Eco-Friendly Alternative for Silicate Depressant in Phosphate Flotation

The quest for environmentally friendly reagents in froth flotation processes has gained significant importance for minimizing ecological impacts. This research investigates the utilization of chitosan polymer as a green depressant for silicate minerals in the direct flotation of phosphate minerals. To understand the behaviour of the flotation feed, zeta potential measurements were conducted to assess the electrical properties of mineral surfaces in the presence and absence of chitosan polymer. Furthermore, the effects of chitosan dosage, pulp pH, and flotation time on the flotation recoveries and concentrate grade of phosphates were studied. Comparative analyses were performed by comparing the flotation recoveries of phosphate minerals achieved using chitosan polymer with those obtained when employing a commercial silicate dispersant, sodium silicate. The findings revealed that at a dosage of 300g/ton, the recovery of phosphate minerals reached approximately 70% when using chitosan polymer, whereas the recovery was only around 40% with the same dosage of sodium silicate dispersant. These outcomes demonstrate the potential of chitosan as an effective and sustainable silicate depressant in the phosphate flotation process under specific conditions.

The surface dissolution process of smithsonite and its effect on flotation behaviour

Previous studies have shown that the dissolution alters the static intrinsic properties of mineral surfaces, such as changing the surface components or active sites, which in turn affects the floatability. In this work, the dissolution process of smithsonite with different particle sizes and its influence on the flotation behaviour were systematically investigated from a dynamic perspective of the dissolution of ions on the mineral surface. Micro-flotation experiments revealed the inhibition of the flotation of smithsonite during the early phases of dissolution, particularly in the case of the fine particle. Inductively coupled plasma optical emission spectroscopy (ICP-OES) tests, Inorganic carbon (IC) tests, and X-ray photoelectron spectroscopy (XPS) analysis indicated that the early phases of the dissolution process of smithsonite exhibited a more rapid rate of zinc ions. However, as the dissolution progressed and a state of saturation was reached, the further dissolution of carbonate inhibited that of zinc ions. Subsequent adsorption measurements and Fourier transform infrared (FTIR) analysis illuminated the transformation in flotation behaviour resulting from the surface dissolution of smithsonite, primarily by affecting the stability of the adsorption of agents. The rapid dissolution rate of ions on the surface of smithsonite led to decreased adsorption stability of (sodium oleate) NaOL and diminished floatability. This phenomenon was particularly discernible on the surface of fine particle smithsonite. This investigation advances a novel mechanism for comprehending the impact of the surface dissolution processes on the flotation behaviour of smithsonite of different particle sizes, providing a theoretical and practical reference for the flotation of fine particles and marginally soluble minerals.

Justification for Criteria for Evaluating Activation and Destruction Processes of Complex Ores

The mining industry is faced with the problem of depletion of reserves of easily beneficiated minerals containing valuable metals. The characteristic features of the ores involved in processing are fine dissemination; low content of valuable components; and similar physical, chemical, surface, and technological properties of minerals, among others. Under such conditions, increasing the efficiency of mineral processing becomes of primary importance. Creating highly efficient, environmentally safe technologies on the basis of deep study of the material, chemical, and mineralogical composition, as well as using and developing methods and techniques for testing mineral materials at successive stages of raw material transformation, enable to solve such problems. Criteria for assessing the flow of technological processes are presented in the article. A complex criterion is substantiated and proposed for quantitative assessment of the degree of physical and energy impact at the stages of ore preparation and flotation enrichment of mineral raw materials. The criterion is calculated on the basis of activation energy data calculated by differential and integral kinetic methods. In addition, an empirical indicator was introduced into the complex criterion, which allows increasing the accuracy of the calculated criterion. This criterion not only allows to estimate the degree of influence from the position of averaged estimation on the full interval of degrees of transformation from 0 to 1, but also gives the possibility to consider the required number of degrees of transformation; for example, if it is necessary to make estimations on narrow temperature intervals. The calculation of empirical parameters for the obtained criterion is carried out before and after the application of physical–energetic methods of influence using thermal analysis.

Application of EDTMPS as a novel calcite depressant in scheelite flotation

In this study, the innovative use of ethylenediamine tetramethylene phosphonic sodium (EDTMPS) as a calcite depressant in scheelite flotation was investigated by flotation experiments, and its selective depression mechanism was revealed by contact angle measurement, FTIR analysis, Zeta potential test and XPS analysis. The flotation experiment results showed that scheelite and calcite could be efficiently separated under the following conditions: pulp pH=9.5, NaOL concentration of 1.5×10−4 mol/L, EDTMPS concentration of 3.0×10−5 mol/L, a scheelite concentrate with WO3 grade of 65.49%, recovery of 83.29% and separation efficiency of 65.29% could be obtained from the artificially mixed minerals. The analysis results of mineral surface properties demonstrated that EDTMPS was strongly adsorbed onto the calcite surface through the reaction between the phosphonate group and the calcium ions, which hindered NaOL adsorption and increased the hydrophilicity of calcite. However, EDTMPS had weak adsorption strength on the scheelite surface, which didn’t affect further adsorption of NaOL, hence, the scheelite remained hydrophobic. Consequently, the selective adsorption of EDTMPS on the two minerals’ surfaces increased a difference in wettability and thus enabling them to be separated by flotation. Finally, the mechanism model of this flotation separation process was established.

Utilization of lead ions to improve surface hydrophobicity and flotation recovery of sulfidized smithsonite

Zinc oxide minerals often coexist with lead minerals in ores, and lead ions (Pb2+) dissolve from lead minerals during grinding and slurry stirring. These dissolved Pb2+ ions affect the surface properties of zinc oxide minerals and the interaction between the mineral surface and flotation reagents, causing a change of the flotation behavior of the zinc oxide minerals. In this study, we systematically investigated the effect of Pb2+ on the surface hydrophobicity and flotation behavior of sulfidized smithsonite in xanthate flotation. The smithsonite floatability was enhanced when Pb2+ was present in the pulp after sulfidization, and the flotation recovery increased from 50.05% to 82.88%. Surface measurements indicated that the sulfide content on the smithsonite surfaces was higher for the smithsonite–Na2S–Pb2+ system than for the smithsonite–Na2S system, and the distribution of the sulfidization products was more compact. Furthermore, by addition of Pb2+ after sulfidization, the characteristic peak of xanthate appeared in the infrared spectrum of smithsonite, and the smithsonite contact angle increased from 36.38° to 60.35°. Therefore, interaction of Pb2+ with the sulfidized smithsonite surfaces enhanced the surface reactivity and promoted xanthate adsorption, thus improving the surface hydrophobicity, and creating favorable conditions to obtain an ideal flotation index.

Evaluating the adsorption mechanism of a novel thiocarbamate on chalcopyrite and pyrite particles

The selective adsorption of surfactants on minerals can strengthen the differences of physical and chemical properties of mineral surfaces, thereby improving the separation efficiency of the refractory minerals. Herein, a novel surfactant S-carboxyethyl-N-benzoyl thiocarbamate (CEBTB) was prepared and utilized as a collector to selective separation of chalcopyrite from pyrite. The adsorption performances and mechanism of CEBTB on chalcopyrite and pyrite surface were studied. It showed that the functional groups (CO, CS and –COOH) of CEBTB could selectively anchor on the chalcopyrite surface and increase its surface hydrophobicity, whereas the adsorption of CEBTB on pyrite surface was weak with the surface hydrophobicity improved insignificantly. Flotation experimental indicated that CEBTB exhibited superior flotation selectivity for chalcopyrite against pyrite than the common collector of SIBX. Batch adsorption experimental results demonstrated that the adsorption of CEBTB onto chalcopyrite surface was performed by a monolayer chemisorption, as well as the adsorption process was endothermic and spontaneous.

Effect of acid surface pretreatment on the floatability difference between ilmenite and titanaugite pre-absorbed by flotation reagents

Minerals in the unqualified ilmenite concentrate collected by flotation reagents appeared the similar surface hydrophobicity and floatability. In this work, acid surface pretreatment was applied to improve the difference in surface properties of ilmenite and gangue minerals pre-absorbed by reagents. Microflotation experiments showed that after ilmenite and titanaugite were treated with high concentrations of NaOL followed by acid surface pretreatment, their recovery differences increased from around 45% to stable 80% regardless of the collector dosage later. AFM and XPS analyses revealed that acid surface pretreatment strengthened the distribution densities of original Fe and new Ti sites and the strengths chemisorbed NaOL onto ilmenite surfaces, while it dissolved intrinsic Ca and Mg sites on titanaugite surfaces. These changes increased the differences in surface hydrophobicity and NaOL adsorption on ilmenite and titanaugite surfaces, which was certified by contact angle and zeta potential. Compared to conventional separation methods, the best result was obtained after rougher flotation concentrate was treated with acid surface pretreatment and three cleaning flotation stages, producing a concentrate with a TiO2 grade of 47.68% and a TiO2 recovery of 26.66%. Taken together, acid surface pretreatment is a potential and novel method to reinforce the separation of ilmenite flotation.

Microplastics existence affected heavy metal affinity to ferrihydrite as a representative sediment mineral

The coexistence of minerals, heavy metals and microplastics in sediment has been widely reported, while the interactions between minerals and heavy metals may be affected by the presence of microplastics. Therefore, to elucidate the effect of microplastics on the interactions between heavy metals and sediment minerals, this study conducted a series of experiments using polystyrene (PS) microplastics, Pb/Cr/Cd and ferrihydrite (Fh). The presence of PS microplastics with ferrihydrite (Fh-MPs200, mass ratio of ferrihydrite to PS of 200:1) improved the adsorption capacity of ferrihydrite, especially with an increase of 36 % for Pb. Morphological characterization demonstrated that the nano-ferrihydrite particles were dispersed on the surface of the PS microplastics, increasing the available reaction sites of the ferrihydrite particles. Furthermore, the results of zeta potential and pH effect showed that the reduction in electrostatic repulsion after adding PS was another critical reason for the increase in Pb adsorption by Fh-MP200. As a result, the presence of PS microplastics enhanced the complexation of Pb ions and the hydroxyl groups on the ferrihydrite surface. This study demonstrated that the presence of microplastics in the sedimentary environment can alter the dispersion and surface properties of minerals, thereby affecting the accumulation and transportation of heavy metals at the water-sediment interface.

Difficulties and Recent Achievements in Flotation Separation of Fluorite from Calcite—An Overview

As an important strategic non-metallic mineral resource, fluorite has been widely used in various industrial fields, such as metallurgy, optics and semiconductor manufacturing, as well as fluorine-related chemical engineering. Since the major gangue minerals of fluorite ore are silicate and carbonate ones, flotation is the main beneficiation method for the concentration. Compared with the relatively easy operation for silicate-type fluorite ore, fluorite concentration from calcite has always been the most difficult challenge in the field of mineral processing. In this review, analyses of the fundamental reasons for the difficulties of flotation separation of fluorite from calcite are performed, from the similar surface properties of both calcium minerals to the deterioration by the interference of dissolved ions in the pulp during grinding and flotation. Recent achievements in the flotation separation of fluorite from calcite as the main contents are comprehensively summarized, covering all aspects of flotation reagents of collectors, depressants and modifiers. Finally, successful examples of industrial practices for fluorite and calcite flotation separation are introduced. This overview provides a detailed and comprehensive reference source for the current research status of fluorite and calcite flotation separation, and some suggestions for future research are provided.

Ionic Polyacrylamides as Stability-Modifying Substances of Soil Mineral Suspensions Containing Heavy Metal Impurities

The accumulation of heavy metal in soils is a serious environmental problem. The aim of this paper was to compare the adsorption mechanism of ionic polyacrylamides (PAMs)—anionic and cationic with different contents of functional groups, on the surface of clay minerals—montmorillonite (type 2:1) and kaolinite (type 1:1), without and with the presence of heavy metal ions (Cr(VI) or Pb(II)). The dependence of solution pH, structure of mineral, type of PAM, ionic form of heavy metal, as well as order of adsorbates addition on the adsorption efficiency and stability of the clay mineral-polymer-heavy metal system was determined. In addition to adsorption and stability studies, electrokinetic and potentiometric titration measurements were performed. It was shown that the mixed PAM+heavy metal adsorption layers modify the surface properties of clay minerals significantly, which in many cases leads to the effective destabilization of the solid suspension and its separation from the liquid phase. Moreover, the most important factor, which influences the adsorbed amount of ionic polyacrylamide, turned out to be the internal structure of layered aluminosilicates and the presence of inter-package spaces capable of adsorbate molecules accumulating. For this reason the obtained adsorption capacity of montmorillonite is about 100 times higher in comparison to kaolinite.

Catalytic activation of persulfate by mechanically-treated natural pyrite: Revisit on the dominant role of sulfur vacancies and size effect

Mechanical treatment has been widely used to modify the surface properties of nature pyrite minerals and improve their catalytic performances; however, the mechanistic relationship still keeps unclear. In this study, we have systematically investigated the effect of milling speed treatment on the surface characteristics of commercial natural pyrite and evaluated the activation ability of persulfate (PDS) for the degradation of sulfamethoxazole (SMX). The results demonstrated that increase in the milling speed of 200–600 rpm could dramatically enhance the degradation and mineralization of SMX, while lower speed (≤200 rpm) exhibited marginal effect. The high milling speeds could reduce the content of sulfate and S(-II) in the pyrite and lead to the occurrence of sulfur vacancies (SVs) for promotional activation of PDS. Nevertheless, the SVs content was not in accordance with increased speed and size effect would mainly contribute to the efficient degradation of SMX. The milling pyrite/PDS system could efficiently treat a molasses-processed wastewater with COD removal of 770 mg/L, suggesting slow-release function of pretreated pyrite and it broaden application potential. In addition, based on the novel conclusion of the mechanism, this study provided a green, efficient and economical pyrite mechanical activation method and its application.

Concentration of oxidized Brazilian zinc ore by flotation: comparative study between anionic and cationic routes

ABSTRACT In this work, a mineralogical characterization by X-ray diffractometry and thermogravimetric analysis of a new Brazilian zinc ore sample was performed. The mineralogical semi-quantification, conducted by normative calculation of the identified minerals, using their theoretical chemical formulas and the contents determined in the chemical analyses was as follows: smithsonite (20.3%), goethite (49.6%), kaolinite (12%), quartz (6.2%), cerussite (3.0%), chlorite (4.0%), dolomite (0.5%) and others (4.4%). Subsequently, bench flotation tests were executed, using sodium oleate (anionic route) and amine (cationic route) as smithsonite collectors. Sodium silicate was used as a depressant of the gangue minerals in both routes tested. These studies showed that the anionic route (30.1% Zn in concentrate and 83% Zn recovery) performed better than the cationic route (17.5% Zn in concentrate and 46.3% Zn recovery). Considering the mineralogical composition of the concentrates obtained in the best flotation results, associated with physicochemical studies published in the literature with the identified minerals, it was evidenced that the difference in performance between the tested routes is due to the influence of ions from the dissolution of carbonates present in the ore on the surface properties of the main gangue minerals (goethite and silicates), especially for the cationic route.

Physical and Chemical Properties of Coal Gasification Fine Slag and Its Carbon Products by Hydrophobic-Hydrophilic Separation.

Coal gasification fine slag is a kind of solid waste with low resource utilization rate. The complex embedding of residual carbon and inorganic minerals (ash materials) is the main reason restricting the efficient resource separation and utilization of residual carbon or ash materials. Hydrophobic–hydrophilic separation (HHS) is a separation technology in which mineral particles with different surface hydrophobicity values are enriched in the water phase and oil phase under the action of mechanical stirring. The water on the surface of hydrophobic particles is replaced by the oil phase to form flocs, which are enriched in the hydrophobic liquid phase, while hydrophilic particles are dispersed into the aqueous phase. In this study, the HHS process was used to separate the carbon/ash from the fine gasification slag produced by a Shenning gasifier, Texaco gasifier, and GSP gasifier of Ningxia Coal Industry Co., Ltd. The physicochemical properties of the original sample and the residual carbon products obtained by hydrophobic–hydrophilic separation were analyzed. The results show that HHS can separate the carbon/ash in the three kinds of fine slag to varying degrees. The carbon element is enriched into the hydrophobic phase to form the concentrates, while the silicon element, oxygen element, and metal element enter the tailings. The spherical ash with different particle sizes distributed on the surface of residual carbon and the gap of the matrix is basically removed, while the ash in the carbon–ash melt is difficult to remove. The ash contents of the concentrate and tailings of fine slag of the Shenning gasifier are 22.58 and 96.28%, respectively, which reach the best ash index compared with that of the other two gasifiers. From the change of mineral surface properties after HHS, the distribution of oxygen-containing groups, benzene rings, Si–O, and clay minerals or carbonate minerals in the three kinds of fine slag residual carbon products is basically similar. Compared with the other two gasifier products, the GSP gasifier concentrate has a larger specific surface area and less ash material, more amorphous carbon structures (less graphitic), and more active sites, resulting in a stronger combustion activity.

Degradation mechanism of surface hydrophobicity by ferrous ions in the sulfidization flotation system of smithsonite

Metal ions commonly exist in the flotation pulp, which will affect the mineral surface properties and lead to a change in the mineral floatability. In this work, the effect of Fe2+ on the flotation behavior of smithsonite was investigated, and the interaction mechanism of Fe2+ with the smithsonite surface in the sulfidization flotation system was clarified. The results of microflotation tests showed that the presence of Fe2+ can greatly reduce the flotation recovery of smithsonite. The results of zeta-potential measurement, time-of-flight secondary-ion mass spectrometry, and X-ray photoelectron spectroscopy indicated that addition of Fe2+ before sulfidization generated FeOOH species and hindered formation of active sulfide species on smithsonite. The results of infrared spectroscopy and contact-angle measurement showed that addition of Fe2+ was harmful for adsorption of the collector on smithsonite, and it was difficult to obtain hydrophobic smithsonite surfaces in the Fe2+–sulfidization–xanthate flotation system. Considering the above results, the presence of Fe2+ depressed adsorption of sulfide ions and the collector on smithsonite, making smithsonite show poor floatability, and it was difficult to obtain the ideal flotation recovery of smithsonite.

Interaction mechanism of Fe3+ with smithsonite surfaces and its response to flotation performance

Iron ions are commonly present in flotation systems. They affect the pulp environment and mineral surface properties, and this changes the mineral floatability. In this work, the effects of Fe3+ on the surface sulfidization characteristics and collector adsorption on smithsonite surfaces were investigated. The results of microflotation tests showed that the addition of 7.5 × 10−4 mol/L Fe3+ decreased the flotation recovery of smithsonite from 49%, which was the recovery achieved by direct sulfidization–xanthate flotation, to 2%. Zeta potential analysis, time-of-flight secondary ion mass spectrometry, and X-ray photoelectron spectroscopy showed that addition of Fe3+ to the pulp reduced the number of active sites on the smithsonite surface and generated hydrophilic Fe–OOH species on the mineral surface. This decreased the reactivity of the mineral surface. The sulfide content of the smithsonite surface after the addition of Fe3+ was lower than that after direct sulfidization. Infrared spectroscopic analysis and contact angle measurements proved that xanthate adsorption on the smithsonite surface was hindered by the addition of Fe3+, which led to poor floatability of the smithsonite.

Effects of iron ion dissolution and migration from phosphorite on the surface properties of dolomite

The partial dissolution of minerals occurs during the production of phosphate ore flotation slurry, producing a certain amount of Ca2+, Mg2+, Fe3+, Al3+, and other metal ions. These metal ions can modify a solution’s chemical environment and the mineral surface properties. Herein, the dissolution and migration behaviors of iron ions in phosphate ore and their effects on the surface properties of dolomite during the flotation slurry process were investigated. Results showed that the maximum Fe3+ content in the slurry was 9.1×10−5 mol/L at pH 5.5. Contact angle and adsorption experiments showed that Fe3+ in the slurry would be adsorbed on the dolomite surface, thus changing its surface properties and reducing the contact angle on the dolomite surface. Results of solution chemistry calculations, zeta potential measurements, and X-ray photoelectron spectroscopic analysis（XPS） indicated the presence of Fe3+ in the slurry in the form of Fe(OH)2+ and FeOH2+, which are adsorbed on the dolomite surface via electrostatic interactions and ultimately reduce the number of adsorption sites of sodium oleate (C18H33NaO2, hereinafter referred to as NaOL). Furthermore, some Fe3+ will react with NaOL to form precipitates of iron oleate, which ultimately reduce the NaOL content in the slurry. Consequently, these two phenomena work to collectively inhibit the hydrophobicity of dolomite in the presence of NaOL.

Effect of temperature on the pH of water flood effluents and irreducible water saturation: A study with reference to the Barail sandstone outcrop of the upper Assam Basin

Low salinity water flooding (LSWF) is a promising strategy for improving oil recovery in sandstone reservoirs, and recent studies have shown that the recovery with low salinity water injection is a function of not only the salinity and ionic composition but also of the pH of injected brine, temperature, and the combined effect of both on the wetting properties of the clay mineral surfaces. Following brine flooding, the initial wettability of sandstone rock surfaces existed when crude oil, formation water (FW), and rock surface interaction were in chemical equilibrium at reservoir condition changes based on brine pH, salinity, temperature, and clay mineralogy. This study proposes pH, core flood temperature, and irreducible water saturation as key parameters in inducing wettability changes in the sandstone porous media. In the present work, the sandstone cores were subjected to flooding at temperatures of 70 °C, 85 °C, and 105 °C and measured the pH of the discharge effluents and initial or irreducible water saturation with respect to varying temperatures. This paper investigates the rise of the pH gradient and irreducible water saturation, Swir with respect to LS flooding, at increasing temperatures using a Barail sandstone core. The key results include the following:The pH of the flood effluents increases with increasing core flood temperature, which indicates a shifting of the existing wetting state of the rock.The combined effects of increasing pH and initial or irreducible water saturation pertaining to low salinity flooding at progressively increasing temperatures result in increasing water wettability of the sandstone rock. Increasing flooding temperatures cause an increase in Swir, which follows a linear relationship.The findings of the paper highlight the link of increasing pH and irreducible water saturation with the water wetting properties of the sandstone reservoir rock and hence the fluid flow or the oil–water relative permeability behaviour. This paper proposes that increased irreducible water saturation and pH of water flood effluents are connected to increasing water wetness in a sandstone rock as a function of elevated temperatures. As adequate work and consensus on the potential effects of temperature on wettability alteration under low salinity water flooding is still lacking, the current work in relation to the Barail sandstone of the upper Assam basin could be a novel reference for understanding of the importance of temperature dependent wettability alteration behaviour in sandstone cores. The findings of this study can assist in the formation of a novel approach towards considering the increasing irreducible water saturation and pH of the brine effluent as an effect of alternatively injection of low salinity water at elevated temperatures on sandstone porous rock.

Regulation mechanism of ultrasonication on surface hydrophobicity of scheelite

Centering on the roles of ultrasound in flotation kinetics, adsorptions of sodium oleate and scheelite, heat of adsorption and mineral surface properties, we investigated the effects of ultrasonic pre-treatment on scheelite surface dissolution, as well as properties and microstructure of sodium oleate solution. As a result, the ultrasonic treatment of sodium oleate or scheelite promoted the adsorption of sodium oleate on the surface of scheelite, which improved adsorption heat, thermal reaction rate, surface hydrophobicity, flotation rate and recovery rate of scheelite. However, the ultrasonic treatment effect of sodium oleate was better than that of scheelite. The dissociation of sodium oleate molecules was promoted by the ultrasound reduces the surface tension of collector solution to enhance its solution activity. In the meantime, the agglomeration structures of sodium oleate were disrupted by ultrasonication to form a small or single molecular structure, which helped accelerate the solute migration speed and reduced induction time between sodium oleate and scheelite. Ultrasonic treatment removed the adhesion of fine particles on the surface of scheelite and the severely corroded mineral surface, which accelerated the dissolution and increased the number of Ca 2+ reactive sites. • The ultrasound increases the hydrophobicity of surface. • The ultrasound improves the flotation rate and recovery rate. • The ultrasound alters the properties and microstructure of NaOL. • The ultrasound decreases the adhesion power between NaOL and scheelite. • The ultrasound adjusts the ratio of Ca/W on the surface of scheelite.

Comparative study on high-voltage nanosecond pulses and dielectric barrier discharge effects on surface morphology and physico-chemical properties of natural pyrrhotite

In this paper we used analytical electron microscopy, potentiometric titration (electrode potential), sorption and flotation measurements and other methods to study changes in the surface morphology, electrochemical, and physicochemical properties of the natural pyrrhotite exposed to nonthermal action of the repetitive nanosecond high-power electromagnetic pulses and low-temperature plasma of dielectric barrier discharge in air at atmospheric pressure. As a result of exposure to high-voltage nanosecond pulses, a sharp shift in the electrode potential of pyrrhotite to the region of negative values caused a decrease in the sorption of the anionic collector on the mineral, a decrease in the hydrophobicity of the surface and flotation of the mineral was due to an increase in the content of oxidized ferric iron on the mineral surface. Dielectric barrier discharge treatment caused the shift of the electrode potential to the region of negative values (–60 mV) in the range of pH 9.7-12, which causes the effect of a decrease in the sorption and flotation activity of pyrrhotite. The advantages of using the short-term (10-30 seconds) energy impacts for structural and chemical modification of the surface and physicochemical properties of sulfide minerals of iron are shown.