Burov, Vladimir Evgenyevich

Burov V.E., Poilov V.Z., Potapov I.S., Kuz’minykh K.G.

The authors investigate the structural and colloid properties of a collector represented by amine hydrochloride treated by ultrasound and included in sylvinite flotation. Using the viscosity–temperature dependences, the Gibbs free energy is calculated for amine hydrochloride with and without treatment by ultrasound. It is found that ultrasound-treated amine added in salt-fat solutions are more stable to coagulation. From the synchronous thermal analysis, IR spectroscopy and X-ray phase analysis, it is inferred that ultrasonic treatment of amine hydrochloride slightly increases crystallinity of amine. The research findings improve understanding of the ultrasound effect on the change in the structural and colloid properties of the collector, which are important to optimizing output, sustainability and efficiency of potassium chloride production by flotation.

Ouyang L., Huang Z., Wang H., He G., Yu X., Burov V.E., Poilov V.Z., Li F., Liu R., Li W., Shuai S., Zhang S., Cheng C., Fu W.

Rhodochrosite and calcite have similar physicochemical characteristics and floatability, making it difficult for conventional flotation collectors to effectively separate the two minerals. In this paper, a novel 3-tetradecylamine propyl amidoxime (TPA) collector with selective and excellent collection capability for rhodochrosite has been investigated. The micro-flotation experiments showed that the flotation performance of TPA is superior to that of the commonly used sodium oleate (NaOL) collector, and the separation of rhodochrosite and calcite can be achieved under neutral conditions. At a slurry pH of 7 and a dosage of 2.0 × 10−4 mol/L, TPA provided a recovery of 88.5% for rhodochrosite and only 15.0% for calcite. The mechanism of interaction between TPA and minerals was examined by contact angle, Zeta potential tests and Fourier transform infrared (FTIR) analysis, which indicated that TPA selectively adsorbed on the surface of rhodochrosite rather than calcite. Finally, the adsorption behavior of TPA molecules on the surface of rhodochrosite was confirmed by Density functional theory (DFT) calculation to be through electrostatic interaction. This paper provides a novel collector for the flotation separation of rhodochrosite from calcite with excellent collecting ability and selectivity, which is significant for the efficient utilization of manganese ore resources.

Chernyshev A.V., Poylov V.Z., Burov V.E., Kuzminykh K.G.

Ouyang L., Huang Z., Wang H., He G., Yu X., Burov V.E., Poilov V.Z., Li F., Liu R., Li W., Shuai S., Zhang S., Cheng C., Fu W.

Shuai S., Huang Z., Burov V.E., Poilov V.Z., Li F., Wang H., Liu R., Zhang S., Cheng C., Li W., Yu X., He G., Fu W.

Since wolframite is usually associated with calcite, the separation and enrichment of wolframite by froth flotation remains a great challenge. Herein, a novel trisiloxane surfactant N-(2-aminoethyl)-3-aminopropyltrisiloxane (AATS) was successful synthesized, which was used for the separation of wolframite from calcite for the first time. The flotation separation performance of AATS was studied by flotation test, and its adsorption mechanism was explored based on contact angle, infrared spectrum analysis (FTIR), zeta potential and density functional theory (DFT) calculation. The results of micro-flotation test and binary mixed ore flotation test binary mixed ore flotation test pointed that AATS had excellent selectivity and more prominent collection capacity for the flotation of wolframite when compared with industrial reagent sodium oleate (NaOL). The measurement results of contact angle proved that AATS improved the hydrophobicity of the wolframite surface. The highly selective adsorption mechanism of AATS surfactant on mineral surfaces were further researched and analyzed by FTIR and zeta potential. The results revealed that AATS surfactant had significant adsorption effect on wolframite, yet almost no adsorption on calcite. DFT calculation indicated that AATS produced electrostatic adsorption with wolframite surface through —N+H3 group.

Burov V.E., Poilov V.Z., Huang Z., Chernyshev A.V., Kuzminykh K.G.

The main source of potassium fertilizers is sylvinite ores consisting primarily of halite (NaCl), silicate and clay-carbonate slurries (clay-salt slurries). Processing of natural potash ores is mainly carried out by the flotation method, which separates KCl, NaCl, and clay-salt slurry. The research is aimed at revealing the effect of sonochemical pretreatment of the depressor reagents, CMC and starch, on dynamic viscosity, aggregate size, electrokinetic potential of these reagent solutions and sylvin flotation performance. It has been established that sonochemical treatment of depressor solutions decreases the size of aggregates of starch molecules by more than 133 times and that of aggregates of CMC molecules from 6 to 4 nm. It has been revealed that sonochemical treatment of anionic CMC solution shifts the electrokinetic potential towards the area of negative values with an increase in acoustic power, while sonochemical treatment of any acoustic power has no effect on the zeta potential of nonionic starch. It has been found that the sonochemical treatment lowers the dynamic viscosity of CMC and starch solutions: the viscosity of CMC solution at a maximum acoustic power of 420 W decreases by 44 % and the viscosity of starch solution at the same acoustic (ultrasonic) power decreases by 70 %. Furthermore, sonochemical pretreatment of sylvin flotation depressors contributes to an increase in KCl recovery and a decrease in the slurry content in the flotation concentrate. The possibility of reducing the consumption of ultrasonic treated depressor is also demonstrated. It is expedient to test the obtained findings in pilot-plant conditions.

Huang Z., Shuai S., Burov V.E., Poilov V.Z., Li F., Wang H., Liu R., Zhang S., Cheng C., Li W., Yu X., He G., Fu W.

Separation of scheelite from calcite by froth flotation using a new amidoxime surfactant - 3-dodecylamine propyl amidoxime (DPA). • A new amidoxime surfactant DPA was used to flotation separate scheelite and calcite. • Scheelite and calcite recovery were 92% and 4.5% respectively. • DPA exhibited preferable selectivity than NaOL in the absence of depressant. • The interaction of DPA surfactant on scheelite surface is electrostatic adsorption. With its high electrical conductivity, thermal creep resistance and compression modulus, tungsten take an irreplaceable position in modern industry, defense, and high technology. Scheelite, as the main raw material of tungsten resources, usually adopts Petrov’ process: steam heating 80 °C-90 °C, stirring in a tank containing 2%-4% sodium silicate solution for more than half an hour to make sodium oleate desorbed on the calcite surface, and repeated cleaning. Herein, a new amidoxime surfactant 3-dodecylamine propyl amidoxime (DPA), had been synthesized and used as a collector for the first time in the flotation separation of scheelite and calcite at room temperature without any sodium silicate, and compared with the traditional collector sodium oleate (NaOL). The flotation behavior of DPA was studied by micro-flotation and mixed binary mineral flotation tests, which showed that DPA has good collection ability and excellent selectivity for scheelite. Meanwhile, the interaction mechanism of DPA on the mineral surface was discussed by FTIR analysis, zeta potential test, contact angle measurement and density functional theory (DFT). FTIR analysis and zeta potential test confirmed that DPA collector had adsorption on scheelite surface but had little effect on calcite. DFT calculation further confirmed that the positively charged –C(NOH)N + H 3 group in DPA had electrostatic adsorption on the negatively charged scheelite surface. The contact angle measurement results revealed that DPA can enhance the surface hydrophobicity of the scheelite particles. Therefore, this highly selective DPA surfactant can achieve effective separation of scheelite and calcite, contributing to environmental protection and sustainable green development of resources.

The article considers the effect of foam-forming compositions of flotation reagents (hydro-chloric amine solution, hydrochloric amine solution with addition of polyethylene glycol 200M and hydrochloric amine solution with addition of triethylene glycol) ultrasonic treatment on the prop-erties of two-phase foams. It was determined that ultrasonic activation of reagent compositions increases a foam specific volume and foam capacity by10.3 and 12.1%, respectively, while the foams become drier by15.2% (in the case of the hydrochloric amine solution), 15.6% (in the case of the hydrochloric amine solution with addition of polyethylene glycol 200M) and 13.3% (in the case of the hydrochloric amine solution with addition of triethylene glycol). In addition, there is an increase in the foam layer stability with an increase in the ultrasonic treatment power by63.1% (in the case of the hydrochloric amine solution), which indicates the ability to control the stability and other characteristics of the foamusing the acoustic method. Due to ultrasonic dispersion, amine floccules are more efficiently distributed over the entire volume of the emulsion, includingthe sur-face of the liquid. It was found that ultrasound changes the above foam characteristics by reducing the surface tension of foam-forming compositions and decreasing collector micelles.

Huang Z., Zhang S., Wang H., Liu R., Cheng C., Shuai S., Hu Y., Zeng Y., Yu X., He G., Fu W., Burov V.E., Poilov V.Z.

Tailings ponds for gangue mineral storage are widely recognized as a dangerous source of toxic minerals and heavy metal-bearing solution. Therefore, recovering valuable minerals and critical elements from tailings is an important means to protect the environment in an economic way. Wolframite tailings usually contain a considerable amount of tungsten resources, but the presence of high content of kaolinite sludge makes it very difficult to recycle wolframite. Herein, a novel sebacoyl hydroxamic acid (SHA) was synthesized and introduced as a novel wolframite collector to effectively utilize wolframite tailings, and its collection performance was compared with that of benzohydroxamic acid (BHA). Micro-flotation tests showed that SHA could still obtain 80% wolframite recovery in the presence of kaolinite slimes. Bench-scale flotation tests indicated that SHA can effectively recover wolframite concentrate with 55.64% WO 3 grade and 75.28% WO 3 recovery from wolframite tailings by the combined shaking table-flotation process. Polarized light microscope observations showed that SHA could promote the formation of hydrophobic agglomerates of wolframite particles. These results show that SHA can be used as an efficient collector for disposing of wolframite tailings, and provide an important reference for the development of efficient and comprehensive utilization of tailings. • Recovering valuable minerals was an effective way to dispose of tailings ponds. • Wolframite was recovered by combined shanking table-flotation process. • SHA showed a stronger collecting ability than traditional collector BHA. • SHA promoted the formation of hydrophobic agglomerates of wolframite particles. • SHA is hopeful to promote the development of efficient utilization of tailings.

Huang Z., Shuai S., Burov V.E., Poilov V.Z., Li F., Wang H., Liu R., Zhang S., Cheng C., Li W., Yu X., He G., Fu W.

The separation and enrichment of scheelite from calcite are hindered by the similar active Ca2+ sites of scheelite and the calcite with calciferous gangue. Herein, a novel trisiloxane surfactant, N-(2-aminoethyl)-3-aminopropyltrisiloxane (AATS), was first explored and synthesized and recommended as the collector for the flotation separation of scheelite from calcite. The micro-flotation and mixed binary mineral flotation tests showed that AATS had excellent collection performance for scheelite and high selectivity for calcite within a wide pH range. At the same time, contact angle and zeta-potential measurements, Fourier transform infrared (FTIR) analysis, and density functional theory (DFT) calculations revealed the relevant adsorption mechanism. The contact angle measurement showed that AATS can increase the contact angle of the scheelite surface from 41.7 to 95.8°, greatly enhancing the hydrophobicity of the mineral surface. The results of FTIR analysis and zeta-potential measurement explained that AATS was electrostatically adsorbed on the mineral surface, and DFT calculation further verified that the -N+H3-positive group in AATS was adsorbed on the negatively charged scheelite surface. Therefore, AATS can realize the expectation of high efficiency and selectivity of minerals and enhance the adhesion between the surface of scheelite minerals and bubbles, providing a fresh approach to industrial production.

Shuai S., Huang Z., Burov V.E., Poilov V.Z., Li F., Wang H., Liu R., Zhang S., Cheng C., Li W., Yu X., He G., Fu W.

Wolframite was separated and extracted from calcite by using a new type of amidoxime surfactant − 3-dodecylamine propyl amidoxime (DPA) as a flotation collector. • A novel amidoxime surfactant DPA was synthesized by lab. • DPA was first introduced in flotation for separation of wolframite from calcite. • DPA has superior selective adsorption performance at wolframite interface. • The wolframite recovery was 96% and calcite only 2 % at pH 7 and 2 × 10 -4 mol/L DPA. This study concentrated on the adsorption features and mechanism of a novel amidoxime surfactant 3-dodecylamine propyl amidoxime (DPA) used as a new wolframite collector on wolframite and calcite surfaces. The flotation experiment showed that DPA collector has a remarkable flotation separation effect on wolframite and calcite. Additionally, the results of the contact angle and zeta potential measurements, and FTIR spectral analysis revealed that the DPA had produced strong electrostatic adsorption on the surface of wolframite, but almost no adsorption on calcite. The results of the DFT calculation showed that DPA had a strong effect on the wolframite surface mainly through the positive charged –C(NOH)N + H 3 group. It provides a new idea for the flotation separation of wolframite and calcite.

Huang Z., Zhang S., Burov V.E., Wang H., Liu R., Cheng C., Shuai S., Li W., Yu X., He G., Fu W., Poilov V.Z.

Abstract No single element has exerted such a deep influence on social organization of mankind as iron. Magnetite is concentrated by froth flotation and used as a raw material to produce iron. However, the conventional surfactants used in the flotation process often lead to the weak collecting performance due to their analogous alkyl hydrophobic group. Here, we report a new trisiloxane surfactant N-(β-aminoethyl)-γ-aminopropyltrisiloxane (AAT) in magnetite flotation, which was compared with the traditional collector dodecylamine (DA). The flotation test results showed that AAT had excellent collecting ability and selectivity for quartz against magnetite. Magnetite concentrate with TFe recovery of 84.79%, TFe grade of 68.84% and SiO2 grade of 6.15% was obtained by using 150 g/t AAT. Density functional theory calculations suggested reactive site of AAT was cationic –CH2N+H3 group, and AAT showed a higher positive grouping Mulliken charge and chemical reactivity that may promote its flotation performance.

Poilov V.Z., Burov V.E., Gallyamov A.N., Fedotova O.A.

This paper covers the problems of improving the efficiency of a specific flotation reagent (amine hydrochloric acid solution) through the dispersion of floccules using preliminary sonochemical activation. The influence of various combinations of acoustic power (from 168 to 420 W in increments of 84 W) and ultrasound exposure time (30, 60 and 150 s) on the physical and chemical characteristics of the mineral/flotation reagent system has been studied. The results demonstrate that preliminary ultrasonic exposure of the reagent reduces the size of amine hydrochloric acid floccules. This, in turn, increases the specific surface area of collector micelles, improving the reagent distribution on the mineral surface. The contact angles for KCl particles were measured after the sonochemical activation and after the amine adsorption, which confirmed better hydrophobization of the sylvite mineral surface. It has been found that higher power values and ultrasonic exposure times produce a more electropositive zeta potential of the reagent solution. It has also been established that the use of a pre-activated solution of hydrochloric acid amine improves KCl recovery as compared with the use of a non-activated flotation reagent. The efficiency of ultrasonic activation of the amine emulsion used at potash flotation plants has been assessed. A positive effect of preliminary ultrasonic exposure of the emulsion on the KCl flotation process was established.The study was carried out with the financial support of the Ministry of Education and Science of the Russian Federation as part of the implementation of the program of activities of the world-class scientific and educational center "Rational Subsoil Use".

Burov V.E., Li J., Meng J.

A lab-scale hybrid anoxic-oxic biofilm reactor (HAOBR) with one anoxic compartment and two oxic compartments in sequence was constructed to treat domestic wastewater in this study. Performance of the HAOBR was evaluated at 25°C and hydraulic retention time 12 hr with reflux ratio increased from 100% to 300% by stages. The results showed that COD, NH 4 + - N , and TN removal presented an increasing trend with the increase of reflux ratio by stages. At the optimal reflux ratio of 300%, removal of COD, NH 4 + - N , and TN averaged 83.9%, 99.0%, and 80.8%, respectively. Analysis about pollutant concentration in each compartment of the HAOBR revealed that the excellent pollutant removal was mainly achieved by the cooperation of nitrification in 3rd oxic compartment and denitrification in 1st anoxic compartment. Denitrification in the anoxic zone of 2nd oxic compartment would also contribute to the nitrogen removal. The higher nitrogen removal of the HAOBR at the reflux ratio of 300% is attributed to the presence of the anammox in the 1st anoxic compartment, which is mainly due to the lower COD concentration in the compartment at the higher reflux ratio. PRACTITIONER POINTS: A hybrid anoxic-oxic baffled reactor was built to treat domestic wastewater. Effect of reflux ratio and mechanism of nitrogen removal were investigated. Reflux ratio 300% was favorable for COD, NH 4 + and TN removal. The removal of COD, NH 4 + and TN averaged 84.4%, 99.0% and 80.8%, respectively. Cooperation of nitrification, denitrification and anammox dominated the high nitrogen removal at the higher reflux ratio of 300%.

Abboud M., Chaouiki A., Chafiq M., Fatimah S., Elboughdiri N., Kang J., Gun Ko Y.

Cheng C., Zeng G., Huang Z.

Ridho M.Z., Pertiwi R., Bagaskara E.D., Rambani R.R., Pitaloka C.S., Wahyuni F.M., Rahmawati I., Reza M.

Yang X., Bao J., Liu Z., Wu D., Cao Y., Xu C.C., Hao H., Zhang Y.

Pan Y., Feng Y., Li Y., Chen J., Li Y.

Hashemi S., Noaparast M., Mabudi A.

Zeng G., Weng W., Zhong S., Chi X., Cai J., Tan W., Chen J.

Cheng C., Zeng G., Huang Z.

Wu K., Lu Y., Wang S., Ma X., Zhong H.

Liu P., Zhou Y., Tian M., Sun W.

Jia K., Lu T., Wu Y., Zhai Y., Jin Y., Lu Y., Li G., Fan G., Wang C., Cao Y.

Cui K., Zhou A., Yu C., Jin S.

Ren Q., Liu P., Yu C., Liu S., Zhang W., Kang J., Sun W., Tian M.

Li Q., Huang L., Hu B., Huang S., Zhou J., Xu Y.

In this study, a novel copper oxide flotation collector, p-methylphenylethyl amide oxime (PEBH), was synthesized via the nitrile–hydroxylamine method, and the flotation behavior of cuprite and calcite under this collector system was studied. The oxime groups of the collector provided additional action sites to form stable chelates with metal ions. The performance of PEBH in cuprite ore flotation was investigated via contact angle measurement, zeta potential measurement, Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and calculations based on the EDLVO (extended Derjaguin, Landau, Verwey, and Overbeek) theory. The flotation experiments of single minerals and artificial mixed minerals indicated that PEBH has excellent flotation ability. At pH 11 and PEBH concentration of 2 × 10−4 mol/L, the cuprite recovery is as high as 96.84 %. Under alkaline conditions of pH 9.0 and 11.0, it can effectively separate cuprite from calcite. Contact angle measurements showed that PEBH significantly enhanced the surface hydrophobicity of cuprite. Zeta potential, FTIR spectroscopy, and XPS analyses revealed the selective chemical adsorption of PEBH onto the Cu sites of cuprite. The results of EDLVO theory-based calculations further confirmed after PEBH action, the attraction between cuprite and bubbles significantly increased, which is beneficial to cuprite flotation. Overall, the results demonstrate that PEBH is a potential collector for the flotation separation of cuprite from calcite.

Zheng Q., Dong L., Shen P., Liu D.

Scheelite and cassiterite often coexist in skarn deposits, which are prone to excessive crushing during dissociation, and gravity separation faces a challenge. However, research on flotation separation is limited. This study aimed to investigate the selective depression behavior and depression mechanism of a combined depressant containing ferric chloride and citric acid on cassiterite to successfully achieve the flotation separation of scheelite and cassiterite. Experimental studies on single minerals and artificially mixed minerals indicated that the individual ferric chloride or citric acid exhibited weak depressive abilities and poor selectivity toward cassiterite. However, a combination of ferric chloride and citric acid in a mass ratio of 3:7 achieved better separation results. At a pH of 8, with a concentration of 1 × 10–3 mol/L mixed depressant, and a sodium oleate concentration of 5 × 10–5 mol/L, scheelite and cassiterite exhibited recovery of 73.35 % and 19.98 %, with grades of 61.76 % and 16.18 %, respectively. Fourier–transform infrared spectroscopy and X–ray photoelectron spectroscopy analyses revealed that the mixed depressant strongly chemically adsorbed on the cassiterite surface, forming FeOOH at ferric species sites. Contact angle measurements indicated a significant reduction in surface hydrophobicity of the cassiterite surface due to mixed depressant components. Atomic force microscopy imaging analysis elucidated the adsorption morphology of the mixed depressant depressive component FeOOH on the cassiterite surface in both 2D and 3D imaging, indicating abundant high–intensity reagent peak adsorption. Therefore, the mixed depressant enhanced the selectivity of the depressant, facilitating the effective separation of scheelite and cassiterite.

Lin Q., Wang S., Ma X., Yang J., Zhong H.

Wang M., Zhao W., Han G., Feng Q.

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.

Zhao W., Yang B., Yi Y., Feng Q., Liu D.

Copper ions (Cu2+) are usually added to activate the sulfidized surface of zinc oxide minerals to enhance xanthate attachment using sulfidization xanthate flotation technology. The adsorption of Cu2+ and xanthate on the sulfidized surface was investigated in various systems, and its effect on the surface hydrophobicity and flotation performance was revealed by multiple analytical methods and experiments. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) characterization demonstrated that the adsorption of Cu2+ on sulfidized smithsonite surfaces increased the active Cu—S content, regardless of treatment in any activation system. The sulfidized surface pretreated with NH4+–Cu2+ created favorable conditions for the adsorption of more Cu2+, significantly enhancing the smithsonite reactivity. Zeta potential determination, ultraviolet (UV)-visible spectroscopy, Fourier transform-infrared (FT-IR) measurements, and contact angle detection showed that xanthate was chemically adsorbed on the sulfidized surface, and its adsorption capacity in various systems was illustrated from qualitative and quantitative aspects. In comparison to the Na2S–Cu2+ and Cu2+–Na2S–Cu2+ systems, xanthate exhibited a higher adsorption capacity on sulfidized smithsonite surfaces in NH4+–Cu2+–Na2S–Cu2+ system. Hence, activation with Cu2+–NH4+ synergistic species prior to sulfidization significantly enhanced the mineral surface hydrophobicity, thereby increasing its flotation recovery.

Shuai S., Huang Z., Burov V.E., Poilov V.Z., Li F., Wang H., Liu R., Zhang S., Cheng C., Li W., Yu X., He G., Fu W.

Since wolframite is usually associated with calcite, the separation and enrichment of wolframite by froth flotation remains a great challenge. Herein, a novel trisiloxane surfactant N-(2-aminoethyl)-3-aminopropyltrisiloxane (AATS) was successful synthesized, which was used for the separation of wolframite from calcite for the first time. The flotation separation performance of AATS was studied by flotation test, and its adsorption mechanism was explored based on contact angle, infrared spectrum analysis (FTIR), zeta potential and density functional theory (DFT) calculation. The results of micro-flotation test and binary mixed ore flotation test binary mixed ore flotation test pointed that AATS had excellent selectivity and more prominent collection capacity for the flotation of wolframite when compared with industrial reagent sodium oleate (NaOL). The measurement results of contact angle proved that AATS improved the hydrophobicity of the wolframite surface. The highly selective adsorption mechanism of AATS surfactant on mineral surfaces were further researched and analyzed by FTIR and zeta potential. The results revealed that AATS surfactant had significant adsorption effect on wolframite, yet almost no adsorption on calcite. DFT calculation indicated that AATS produced electrostatic adsorption with wolframite surface through —N+H3 group.

Sun H., Ma X., Fei L., Cao Z., Zhong H., Wang S.

Efficient recovery of fine mineral particles is challenging for minerals flotation due to a small particle mass and high specific surface area. This work innovatively applied a multifunctional surfactant 2-dodecanoylamino-pentanedioic acid (DPA) for achieving flocculation and recovery of fine rhodochrosite. Interestingly, the formation of larger aggregation induced by DPA, instead of sodium oleate (NaOL), was observed and the medium particle size (d50) was 2.29 times than that of NaOL, resulting in more strong collecting ability for fine rhodochrosite particles (with a recovery of 82.5% for 0.1 mmol/L DPA and 35.3% for 0.1 mmol/L NaOL). Analysis with EDLVO theory illustrated that the hydrophobicity force is one of the factors that induces hydrophobic flocculation, along with electrostatic repulsion, the Van der Waals force, and weak interaction. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations revealed the “weak-to-medium” hydrogen bond formation among the amide groups or amide and carboxyl functional groups in the DPA complex, further enhancing aggregation between rhodochrosite fine particles. These discoveries are beneficial for providing new insights into aggregation generation among fine particles in the presence of surfactants containing multiple functional groups.

Qin W., Hu J., Zhu H., Jiao F., Jia W., Han J., Chen C.

The flotation separation of magnesite from calcium-containing minerals has always been a difficult subject in minerals processing. This work studied the inhibition effects of carboxymethyl cellulose (CMC), sodium lignosulphonate, polyaspartic acid (PASP) and sodium silicate on flotation behaviors of magnesite, dolomite and calcite, providing guidance for the development of reagents in magnesite flotation. The micro-flotation results showed that among these four depressants, sodium silicate presented the strongest selectivity due to the highest recovery difference, and the flotation separation of magnesite from dolomite and calcite could be achieved by using sodium silicate as the depressant. Contact angle measurement indicated that the addition of sodium silicate caused the largest differences in surface wettability of the three minerals, which was in line with micro-flotation tests. Furthermore, zeta potential test, the Fourier transform infrared (FT-IR) spectroscopy and atomic force microscope (AFM) imaging were used to reveal the inhibition mechanism of sodium silicate. The results indicated that the dominated component SiO(OH)3− of sodium silicate could adsorb on minerals surfaces, and the adsorption of sodium silicate hardly affected the adsorption of NaOL on magnesite surface, but caused the reduction of NaOL adsorption on dolomite and calcite surfaces, thereby increasing the flotation selectivity.

Zou S., Wang S., Ma X., Yang J., Zhong H.

The high consumption of depressants in the flotation separation of sulfide lead-zinc ores would cause serious environmental problems, and conventional dithiocarbamate collectors suffered from the drawbacks of low flotation activity and poor selectivity. Hence, it’s urgent to develop efficient collectors for the separation of galena and sphalerite. In this study, a novel morpholine dithiocarbamate propylene ester (MDPE) was designed and synthesized by the introduction of morpholine structure containing the C-O-C group, aiming to improve the surface activity and selectivity of the molecule. Surface tension tests indicated that MDPE exhibited a higher surface activity and stronger hydrophobicity than conventional collector N,N-diethyl dithiocarbamate propiononitrile ester (Ester-105) due to the introduction of morpholine structure. Microflotation experiments revealed that compared with Ester-105, higher flotation recovery of galena (90.75%) with significantly improved flotation selectivity against sphalerite by using MDPE of 2 × 10−4 mol/L at low alkalinity (pH=8.5) was obtained. Surface wettability measurements displayed that MDPE enhanced the hydrophobicity of galena surfaces more obviously than sphalerite. UV–vis spectra showed that MDPE preferred to interact with Pb2+ rather than with Zn2+. Adsorption experiments elucidated that the adsorption capacity of MDPE for galena was stronger than that for sphalerite. FTIR spectra and XPS proved that MDPE might chemically adsorb on the surface of galena through the formation of C-S-Pb structure. DFT calculations were conducted to demonstrate that the introduction of morpholine structure improved the chemical activity of the molecule.

Burov V.E., Poilov V.Z., Huang Z., Chernyshev A.V., Kuzminykh K.G.

The main source of potassium fertilizers is sylvinite ores consisting primarily of halite (NaCl), silicate and clay-carbonate slurries (clay-salt slurries). Processing of natural potash ores is mainly carried out by the flotation method, which separates KCl, NaCl, and clay-salt slurry. The research is aimed at revealing the effect of sonochemical pretreatment of the depressor reagents, CMC and starch, on dynamic viscosity, aggregate size, electrokinetic potential of these reagent solutions and sylvin flotation performance. It has been established that sonochemical treatment of depressor solutions decreases the size of aggregates of starch molecules by more than 133 times and that of aggregates of CMC molecules from 6 to 4 nm. It has been revealed that sonochemical treatment of anionic CMC solution shifts the electrokinetic potential towards the area of negative values with an increase in acoustic power, while sonochemical treatment of any acoustic power has no effect on the zeta potential of nonionic starch. It has been found that the sonochemical treatment lowers the dynamic viscosity of CMC and starch solutions: the viscosity of CMC solution at a maximum acoustic power of 420 W decreases by 44 % and the viscosity of starch solution at the same acoustic (ultrasonic) power decreases by 70 %. Furthermore, sonochemical pretreatment of sylvin flotation depressors contributes to an increase in KCl recovery and a decrease in the slurry content in the flotation concentrate. The possibility of reducing the consumption of ultrasonic treated depressor is also demonstrated. It is expedient to test the obtained findings in pilot-plant conditions.

Xie X., Li B., Xie R., Tong X., Li Y., Zhang S., Li J., Song Q.

• Al 3+ combined with GG can achieve the flotation separation of smithsonite from calcite. • Al 3+ enhanced the selectivity of GG on calcite. • The hydrolysates of Al 3+ in the solution system were selectively adsorbed on the surface of calcite. • GG was selectively adsorbed on the surface of calcite by Ca-O and Al-O bond. Naturally, there are similar surface physicochemical and floatability properties between smithsonite and calcite, and their flotation separation has always been challenging. This research studied the function and mechanism of Al 3+ and guar gum (GG) on the flotation separation of calcite from smithsonite through micro-flotation, chemical calculation of solution, adsorption measurement, FT-IR analysis, Zeta potential measurement and XPS analysis. The result of micro-flotation showed that Al 3+ and guar gum as depressant could separate smithsonite from calcite effectively. Results of chemical calculation of solution, adsorption measurement, FT-IR analysis, Zeta potential and XPS analysis measurement indicated that the adsorption difference of Al 3+ and GG on smithsonite and calcite surface was obvious. The hydrolyzate of Al 3+ selectively adsorbed on calcite and provided the Al adsorption sites for GG. GG selectively adsorbed on the calcite surface through Ca-O bond and Al-O bond, which was formed by the O in the phosphate and hydroxyl groups with Ca and Al sites on the calcite surface. Al(OH) 3 and Al 2 O 3 produced by Al 3+ in the solution system were also selectively adsorbed on the calcite surface, and hinder the adsorption of NaOL, finally achieving the flotation separation of smithsonite from calcite.

Chen Y., Guo X., Chen Y.

• Phytic acid (PA) was used as depressant in the flotation of smithsonite from calcite. • The floatability of calcite was strongly reduced by PA. • The flotation of smithsonite was slightly affected in the presence of PA. • PA reacted with the Ca sites on calcite and showed stronger adsorption than that on smithsonite. • Calcite surface was covered by PA adsorption layer which inhibited the adsorption of NaOL. The flotation separation of smithsonite from calcite is challenging due to their highly similar surface properties. In this study, phytic acid (PA) was applied as a depressant to achieve the flotation separation of smithsonite from calcite for the first time. Micro-flotation experiments indicated that PA showed a strong depressing effect on calcite flotation while a slight effect on smithsonite at pH 9.5. Smithsonite and calcite could be well separated by flotation in the presence of PA and with sodium oleate (NaOL) as collector. Based on a series of tests including zeta potential, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the selective depressing mechanism of PA was well investigated and explained. It was found that the selective depressing performances of PA on smithsonite and calcite flotation were mainly attributed to the selective adsorption of PA based on the different active sites on minerals surfaces. As for calcite, a high adsorption degree of PA caused by strong reaction with the active Ca + sites exposed on calcite surface inhibited the subsequent adsorption of NaOL. On contrast, the much less PA adsorption occurred on smithsonite surface hardly affected the further adsorption of NaOL. The adsorbed aggregates layer covering on PA-treated calcite surface was also visually observed by atomic force microscope. These findings confirm the excellent selective depressing effect of PA on flotation separation of smithsonite and calcite, providing theoretical and practical reference for the clean flotation of smithsonite.

Sun K., Nguyen C.V., Nguyen N.N., Nguyen A.V.

The flotation separation of water-soluble salt minerals has to be conducted under the condition of saturation in brines which represents a challenging but exciting topic of colloid and surface chemistry. Despite several proposals on explaining the success of this industrial application for many decades, our understanding of the flotation separation is still far from complete yet, owing to the complexity of the highly selective collection of salt crystals by air bubbles in brines. Here, we thoroughly review the experimental results for halogen, oxyanion, and double salts and match them with the proposed theories on the flotation of soluble salts to identify the agreed and disagreed cases. The experimental results show that the flotation of these salts varies from collectors (surfactants applied to control the crystal hydrophobicity) to collectors and is strongly affected by the brine ion composition and pH conditions. We find some exceptional flotation results that cannot be simply explained by the crystal surface charge and wettability. Furthermore, we outline several disputes and discrepancies between the experiments and the theories when different collectors are applied. Apart from the extensive consideration of surface hydration, the presence of external ion species exhibits ubiquitous effects on the surface properties of salt crystals and the colloidal properties of collectors. We conclude that the interactions between salt ions, water molecules, collectors, and salt crystals must be considered more thoroughly, and the activity of collectors at the air-liquid interface should also be the focus. Advanced techniques such as molecular dynamics simulation, atomic force microscopy, X-ray photoelectron spectroscopy, and sum-frequency generation spectroscopy are expected to be promising research tools for future studies.

Dai Q., Li L., Hoang T.K., Tu T., Hu B., Jia Y., Zhang M., Song L., Trudeau M.L.

Secondary aqueous zinc-ion batteries have been widely investigated recently due to their high energy density , low-cost, and environmental friendliness, compared to organic batteries. Zinc based batteries still have unstable cycle performance, especially at a low current density , which usually presents severe declination of the specific capacity during cycling. Thus, it is important to improve the electrochemical performance of the secondary aqueous zinc-ion batteries in order to broaden their applications. The electrode materials are among the key factors that influence the electrochemical performance of batteries. On the cathode side , manganese oxides have been widely applied because they have a high theoretical specific capacity. Moreover, they can be conveniently prepared or obtained from natural minerals. However, the mechanism of these cathode materials in the aqueous electrolyte is still not clear, hindering the effective improvement of their electrochemical performance. The zinc anode of the zinc-ion batteries also suffers from the hydrogen evolution, the dendrite formation, and surface passivation . Plus, there are issues such as the decomposition of water, narrow operating temperature and electrochemical stable window, involved in the aqueous electrolyte due to the intrinsic properties of water. These drawbacks seriously affect the cycle stability and the service life of the battery. Herein, the application and the mechanism of different manganese oxides, the investigation of the zinc anode, the aqueous electrolyte, and the effect of separator in the secondary aqueous zinc batteries are reviewed. Furthermore, the future prospects of this system are elaborated. • The secondary aqueous zinc-manganese batteries were systematically reviewed from multiple aspects. • Different electrochemical reaction mechanism of different manganese-based cathodes was reviewed. • The zinc dendrite and the hydrogen evolution issues of the anode side were elaborated. • The drawbacks with the aqueous electrolyte were sorted out. • The effect of the separator and recent progress were illustrated.

Wu J., Yang B., Song S., Quintana M., Jia F., Tian X.

• NBPT could achieve a satisfactory floatability of molybdenite fines. • NBPT preferentially adsorbed on the edges through chemical adsorption . • The S 3p orbital of NBPT hybridized with the Mo 4d orbital. • NBPT selectively adsorbed on hydrophilic edges and rendered them hydrophobic. In this work, a novel collector N-( N -butyl) thiophosphoric triamide (NBPT) was explored to improve the flotation of molybdenite fines. The flotation performance was evaluated through micro-flotation tests, and the interaction mechanism was investigated through Zeta potential, Fourier Transform Infrared Spectrometer (FTIR), adsorption capacity, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), Atomic Force Microscopy (AFM) and density functional theory (DFT) calculations. Flotation results manifested NBPT could greatly improve the flotation of molybdenite fines. Zeta potential, FTIR, adsorption capacity and AFM measurements proved NBPT was more inclined to adsorb on molybdenite surface. XPS and ToF-SIMS analysis showed NBPT chemically adsorbed on molybdenite surface via the bonding between P S groups with Mo atoms. DFT calculations reconfirmed NBPT had much stronger affinity towards edges ( Eads = -657.69 kJ/mol) than faces ( Eads = -39.96 kJ/mol). Moreover, NBPT strongly interacted with molybdenite edges through the hybridization of the S 3p orbital of NBPT with the Mo 4d orbital of molybdenite to form strong covalence bond. As a result, NBPT could be utilized as a potential collector to enhance the flotation of molybdenite fines.

Yang D., Li B., Feng D., Xie X., Mo F., Tong X., Song Q.

Naturally, smithsonite and calcite have similar surface physico-chemical properties so as similar floatability, hence their separation via flotation has always been one of the difficult problems in mineral processing industry. To solve this dilemma, efficient flotation reagents which could expand the difference in surface properties could be a good bailout. In this study, guar gum was successfully employed as depressant for calcite during the smithsonite flotation, and its function mechanism were studied by micro flotation, and X-ray photoelectron spectroscopy (XPS) analysis, Fourier transform infrared (FT-IR) analysis, and Zeta potential measurement. The result of micro flotation showed that using guar gum as a depressant can effectively separate smithsonite from calcite by flotation; the analysis results of XPS, FT-IR, and Zeta potential measurements showed that the adsorption behavior of Guar gum on calcite and smithsonite was significantly different. Guar gum selectively adsorbed on the calcite surface and formed strong Ca-O chemical bond via phosphate group and hydroxide radical, which reduced the number of Ca adsorption sites on the calcite surface and thus hindered the interaction between sodium oleate and calcite surface, realizing the effective flotation separation of smithsonite from calcite. • GG helps achieve effective flotation separation of smithsonite. • GG selectively forms strong Ca-O bond on calcite surface. • GG adhesion on calcite surface inhibits NaOL adsorption.

Zhao W., Yang B., Liu D., Feng Q.

This work proposed a promising method to increase the flotation recovery of smithsonite in the sulfidization xanthate system by activation with copper ions prior to addition of Na 2 S. The effect of copper ions on surface properties, sulfide adsorption, and floatability of smithsonite was examined using micro-flotation experiments, solution composition determination, and surface measurements. The flotation recovery of smithsonite activated by copper ions was superior to that in the direct sulfidization system, along with a maximum increase by approximately 19%. It was ascribed to an increase in active sites on smithsonite surfaces due to the formation of –O–Cu complexes. Cu 2+ in the pulp solution bonded to O sites on smithsonite surfaces, and Cu(OH) + interacted with –OH species through dehydration reaction to form activation products. It was beneficial to the interaction of sulfide species with smithsonite surfaces, and more sulfidization products formed on the mineral surface. The sulfidization products were composed of copper sulfide and zinc sulfide species in the enhanced sulfidization system, and copper sulfide species exhibited higher affinity to xanthate than zinc sulfide. It greatly improved the surface hydrophobicity of smithsonite after enhanced sulfidization with copper ions, thereby promoting the flotation recovery of smithsonite, which is significant for the sustainable production of refractory zinc oxide ores. • Copper species could interact with O sites on smithsonite surfaces to produce –O–Cu complexes. • Both copper sulfide and zinc sulfide species formed on smithsonite surfaces after enhanced sulfidization. • More sulfide species adsorbed on smithsonite surfaces with copper ions. • Flotation recovery of smithsonite was significantly increased after activation by copper ions.