Sodium Isopropyl Xanthate Research Articles

Chemical stability of xanthates, dithiophosphinates and hydroxamic acids in aqueous solutions and their environmental implications

Currently there is a wide variety of collectors used in mineral processing, the xanthates being the most used in sulfides flotation. Unfortunately, it is known that xanthates are not stable compounds and their decomposition generates carbon disulfide (CS2), a substance that is considered toxic. These aspects have motivated the search for collectors that exhibit superior performance without the health, safety and environmental (HSE) concerns associated with xanthates. In this study, the chemical stability of three xanthates of different alkyl groups (sodium ethyl xanthate (SEX), sodium isopropyl xanthate (SIPX) and potassium amyl xanthate (PAX)) was evaluated by UV/Vis spectroscopy, as a function of pH and time. Similarly, the chemical stability of three chelating collectors was evaluated: sodium di-isobutyl dithiophosphinate (SDIBDTPI), benzohydroxamic acid (BHA) and octanohydroxamic acid (OHA). Likewise, the surface tension of their aqueous solutions was measured making use of the Du Noüy method, to determine the critical micelle concentration (CMC). The results showed that the xanthate UV/Vis absorption spectra reflect the presence of a chemical reaction as the pH decreases from 4 to 2.5, which results in the formation of carbon disulfide (CS2). In addition, the generation of CS2 is favored as time elapses and the pH of the solutions decreases from 10 to 6, regardless of the hydrocarbon chain length. Conversely, dithiophosphinate and hydroxamic acids present greater chemical stability, although they form micelles at a certain concentration (CMC), a phenomenon that is not observed with xanthates. By not hydrolyzing, oxidizing, or decomposing into other chemical species, SDIBDTPI, BHA, and OHA may be considered environmentally friendly reagents. In the above context, it is important to promote the adoption of these collectors in mineral processing.

Synthesis of high-efficient TiO2/clinoptilolite photocatalyst for complete degradation of xanthate

Acid leaching clinoptilolite-based composite photocatalyst coated with TiO2 nanoparticles was prepared by a hydrothermal method. Photocatalytic properties of the obtained TiO2/clinoptilolite were evaluated through the degradation of sodium isopropyl xanthate (SIPX) under UV light irradiation. The as-prepared samples were characterized by XRD, SEM, TEM, TG-DSC, N2 adsorption-desorption, XPS, FTIR, and UV–vis DRS in detail. Compared with pure TiO2, TiO2/clinoptilolite significantly enhanced the photodegradation efficiency of SIPX due to the synergistic effect of the composite. Over 90% of SIPX could be removed within 30 min with a TiO2/clinoptilolite dosage of 1.0 g/L under neutral condition. The influences of some parameters such as the TiO2 loading amount, H2O2 dosage, calcination temperature, and initial SIPX concentration on removal efficiency were investigated systematically. The results indicated that all the photocatalytic degradation process of SIPX followed a pseudo-first-order reaction kinetic model. Moreover, the stability and applicability of TiO2/clinoptilolite were also studied. The possible degradation pathway and mechanism of improved photocatalytic activity were proposed. It showed that the novel catalyst would have a promising application prospect in the field of flotation effluent treatment.

Synthesis of clinoptilolite-supported BiOCl/TiO2 heterojunction nanocomposites with highly-enhanced photocatalytic activity for the complete degradation of xanthates under visible light

Novel ternary BiOCl/TiO2/clinoptilolite (BTC) nanocomposites with highly-enhanced photocatalytic activity under visible light were prepared by a facile hydrothermal route combining with a water bath precipitation procedure. In the nanocomposites, BiOCl nanosheets (BNSs) and TiO2 nanoparticles (TNPs) were uniformly dispersed on the surface of flake-like clinoptilolite. Sodium isopropyl xanthate (SIPX) was selected as the target contaminant to evaluate the photocatalysis of the obtained samples. Obviously, BTC photocatalyst showed more excellent adsorption and degradation performance for SIPX than single TiO2 or BiOCl as well as their binary composites with clinoptilolite. Given that the characterization analysis and experimental results, the highly-enhanced photocatalytic activity was mainly attributed to the effective construction of BiOCl/TiO2 heterojunction and the excellent adsorption ability of clinoptilolite in BTC nanocomposites. Radical scavenger tests demonstrated that superoxide radical anions (·O2-) and photogenerated holes (h+) were the dominant active species in the reaction system. It is proposed that such novel nanocomposites could be used as efficient photocatalysts for the complete degradation of xanthates under visible light.

New Eco-Friendly Xanthate-Based Flotation Agents

An optimal laboratory two-step procedure was developed for sodium/potassium O-alkyl carbonodithioate (sodium/potassium alkyl xanthates) production in the form of aqueous solutions. Sodium isopropyl xanthate (Na-iPrX), as the most effective salt in a real ore flotation process, was also produced at an industrial level and introduced as a collector for copper ores. In order to reduce toxicity of the flotation process and improve sustainability by minimising environmental impacts, collector efficiency and selectivity in the flotation process were studied in relation to possible synergism of xanthates combined with the derived biomass and biodegradable green reagents levulinic acid, 5-hydroxymethyl-2-furanacrylic acid (HMFA), and condensation product of hydroxymethylfurfural and levulinic acid. Optimal content of 30% of HMFA in the collector pointed to the possibility of substitution of commercial xanthate collector without significantly affecting its efficiency/selectivity. The density functional theory (DFT) calculations provided insights into the interaction mechanism of Na-iPrX and HMFA with cooper. The benefits of the presented method highlight production simplicity, mild reaction conditions, high purity and yield of products, no by-products, and technological applicability on an industrial scale.

Mechanisms of pyrite biodepression with Acidithiobacillus ferrooxidans in seawater flotation

It has been shown that bacterium Acidithiobacillus ferrooxidans can be used to depress pyrite in seawater flotation at natural pH, which opens the possibility for its use as an alternative to lime to depress pyrite in copper sulfide flotation. In order to have a better understanding of the mechanisms involved in pyrite depression with A. ferrooxidans, different kind of experiments were carried out, including, contact angle, attachment kinetics, and streaming potential measurements. All these experiments were carried out in seawater. Biodepression of pyrite was improved by increasing the pH from 4 to 8, with a decrease in recovery from 92% to 36%. This increase in depressing capability was accompanied by an increase in attachment density of bacteria on pyrite, from 2.58×108 bacteria/g to 1.99×109 bacteria/g at pH 4 and 8, respectively. These results suggest that the mechanism of depression is related to the attachment of bacteria to the pyrite surface. The streaming potential measurements showed that both bacteria and pyrite were negatively charged at pH 8. This indicates that electrostatic forces are mainly repulsive, therefore other forces cause the attachment of bacteria to the mineral. The contact angle of pyrite conditioned with seawater at pH 8 was 16°, which increased to 54° when collector (sodium isopropyl xanthate) was added, indicating an increase in hydrophobicity. Nevertheless, when pyrite was previous conditioned with bacteria, the contact angle increased only to 44° when collector was added. Thus, the collector has a lower influence in the hydrophobicity of pyrite when the mineral has interacted with bacteria A. ferrooxidans.

Assessment of the use of lignosulfonates to separate chalcopyrite and molybdenite by flotation

Molybdenum is the most important by-product of Chile's copper mining industry, and during the last decade gained international relevance because of its high price At mining deposits, copper and molybdenum are extracted together and then separated in a process consisting of several stages of flotation using sodium hydrosulfide (NaHS) as key reagent. However, environmental issues related to the potential emissions of toxic hydrosulfide gas (H2S), and bad odors make necessary the development of new environmentally friendly processes that incorporate non-toxic reagents. In this work, we hypothesize that a selective separation of chalcopyrite and molybdenite by flotation can be achieved by using lignosulfonates instead of NaHS. This approach was evaluated by testing the effect of lignosulfonates, produced by reacting kraft lignin with sodium sulfite and formaldehyde, and commercially available lignosulfonates, on molybdenite and chalcopyrite flotation. Chemical characterization of lignosulfonates was performed by determination of molecular mass, elemental analysis, fourier transform infrared, and mass spectroscopy with inductively coupled plasma. Also, interactions between molybdenite and lignosulfonates were studied through measurements of electrophoretic mobility. The main conclusions of the work are that molybdenite flotation can be depressed by the action of lignosulfonates, and such depressing effect increases with pH because of the interactions between lignosulfonates with the metallic calcium sites existing on the surface of the mineral particles. The experimental results also indicate that lignosulfonates can depress chalcopyrite flotation when sodium isopropyl xanthate is used as a collector, but this effect can be completely mitigated by using potassium amyl xanthate as a collector, thus, making it possible the potential separation of both minerals.

Molecular Biology-Based Analysis of the Interactive Effect of Nickel and Xanthates on Soil Bacterial Community Diversity and Structure

Metals and mineral flotation collector’s toxicity to the soil living system greatly compromise the sustainability of mining and ore processing. Their effects on the soil microbial community, the most active soil component, remain less understood and addressed particularly with regards to xanthates and their combination with metals. This study analyzed the interactive effects of Ni and xanthates, potassium ethyl xanthate and sodium isopropyl xanthate, on the soil bacterial community through an efficient molecular biology-based technique, the Miseq (Illumina). Both soil microbial community diversity and structure were more affected by xanthates than by Ni. The five most dominant phyla, representing 96.31% of the whole bacterial community, comprised Proteobacteria (54.16%), Firmicutes (17.51%), Actinobacteria (15.59%), Acidobacteria (4.87%), and Chloroflexi (4.16%). Different soil treatments exhibited greater difference in the species abundance/dominance than in the species numbers. Proteobacteria was the most dominant in the presence of xanthates, individually or in mixtures with nickel, while Firmicutes exhibited its highest proportion in the Ni/xanthate-treated samples. The most abundant and proportionally different bacterial species between different treatments were presented. The most abundant bacterial strains identified should be explored more for their potential application in biomining and for the prediction and biologically-based treatment and remediation of Ni and xanthate-contaminated systems.

Flotacijska ispitivanja majdanpečke rude bakra u cilju poboljšanja iskorišćenja bakra i kvaliteta koncentrata primenom različitih kolektora

This paper presents the results of mineralogical and flotation studies on the copper ore from the deposit North Revir in the Copper Mine Majdanpek, using different collectors. XRD and ore mineralogical analysis showed that the most common minerals are pyrite and chalcopyrite. Chemical analysis confirm that it is a complex low-grade copper ore with average copper content of 0,273%. The content of precious metals (Au and Ag) was 0.2 g/t and 1.2 g/t, respectively. The main aim of flotation studies have been the effect of collector type on the recovery and concentrate grade in the copper flotation process. Various collectors and combinations of them were used in the rough flotation tests of copper ore. The copper recovery was in the range from 79.43% (test no. 4) to 84.96% (test no. 7). The best flotation results were obtained with mixture collectors of sodium isopropyl xanthate (Z11), dialkyl dithiophosphinates (Aerophine 3404) and SKIK BZ 2000. The collector's dosages of 20 g/t Z11, 8 g/t AP3404 and 8 g/t SKIK BZ 2000 produced the copper recovery (84.96 %) with copper concentrate grade of 1.52% .

Degradation of sodium isopropyl xanthate from aqueous solution using sonocatalytic process in the presence of chalcocite nanoparticles: Insights into the degradation mechanism and phyto-toxicity impacts

In the present work, the sonocatalytic degradation of sodium isopropyl xanthate (SIPX) was investigated in the presence of Cu2S nanoparticles. Cu2S nanoparticles were produced by means of a high-energy planetary mechanical ball milling method within the processing times of 0.5, 1.5, 3 and 4.5 h. The physical and chemical characteristics of Cu2S particles were studied before and after ball milling process using various analytical techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) coupled Energy-dispersive X-ray spectroscopy (EDX), atomic absorption spectroscopy (AAS) and nanoparticles size distribution (NSD). The XRD pattern of the samples confirmed the presence of tetragonal and cubic crystalline phases of Cu2S. In addition, the results of SEM and NSD analysis showed that the increase in the ball milling time from 0.5 to 4.5 h notably decreased the size of nanoparticles to the range of 20–40 nm. Furthermore, AAS result showed that the concentration of Cu+ ions was much lower than that of the accepted value in the aqueous media (0.009 mg/L) after 60 min of the sonocatalysis. The study on the effects of the main key parameters showed that 93.99% of SIPX (10 mg/L) was removed during 60 min of the sonocatalytic process under the optimum conditions: pH of 7.3, Cu2S concentration of 1.5 g/L, and ultrasonic power of 150 W. The sonocatalytic degradation mechanism was thoroughly examined in the presence of different organic and inorganic scavenger compounds, including ethanol, EDTA, NaCl and Na2SO4. The obtained results confirmed OH and holes (h+) as the dominant oxidizing species in Cu2S catalyzed sonolysis. In order to get the benefits of the integrated sonocatalytic process, different rate enhancing compounds were introduced into the system. For the first time, the S2O82− and Cu2S catalyzed sonolysis (US/Cu2S/S2O82−) system was introduced as an efficient and novel sonocatalytic system for fast degradation of SIPX. Moreover, the phyto-toxicological assessments proved the reduction in the toxicity of the sonocatalytic-treated SIPX solution by increase in the reaction time, from 20 to 60 min.

EFFECTS OF ADMIXTURES ON THE CRYSTALLISATION RATE OF GYPSUM A BATCH CRYSTALLISATION STUDY

This paper descripbes a study on the effects of admixtures on the crystallization rate of gypsum. Two different types of biodegradable admixtures commonly used as flotation agent in copper/zinc concentrate production, namely, sodium isopropyl xanthate (=SIPX) and isopropyl thionocarbamate were investigated in this study. A laboratory batch crystallizer was used in this study, and the experiments were run using seeded method. The rate of desupersaturation or the time required to reach the equilibrium concentration was compared for varying admixture oncentrations. It was discovered that the added seed crystals started growing imediately upon addition into the supersaturated solution, i.e. there was no induction time.Results of this batch crystallizationstudy suggest that addition of admixtures individually or in combination, significantly affects the crystallization kinetics and in particular, reduces the rate of crystallization of gypsum. Activation energies were determined using three different temperatures, and the values obtained mostly agreed with other published values, i.e. 60.00 ± 3.00, 57.39 ± 2.87, and 37.65 ±1.88 kj/mol, for pure gypsum, isopropyl yhionocarbamate, and SIPX, respectively.Keywords : activation energy; admixtures; CaSO4.2H2O; crystallization, gypsum; reaction rate

Toxicity of nickel to soil microbial community with and without the presence of its mineral collectors-a calorimetric approach.

The toxicity of nickel and three of its main collectors, sodium isopropyl xanthate (SIPX), sodium ethyl xanthate (SEX), and potassium ethyl xanthate (PEX) to soil microbial activity, was analyzed, individually and as a binary combination of nickel and each of the collectors. The investigation was performed through the microcalorimetric analysis method. For the single chemicals, all power-time curves exhibited lag, exponential, stationary, and death phases of microbial growth. Different parameters exhibited a significant adverse effect of the analyzed chemicals on soil microbial activity, with a positive relationship between the inhibitory ratio and the chemical dose (p<0.05 or p<0.01). A peak power reduction level of 24.23% was noted for 50μgg-1 soil in the case of Ni while for the mineral collectors, only 5μgg-1 soil and 50μgg-1 soil induced a peak power reduction level of over 35 and 50%, respectively, in general. The inhibitory ratio ranged in the following order: PEX>SEX>SIPX>Ni. Similar behavior was observed with the mixture toxicity whose inhibitory ratio substantially decreased (maximum decrease of 38.35%) and slightly increased (maximum increase of 15.34%), in comparison with the single toxicity of mineral collectors and nickel, respectively. The inhibitory ratio of the mixture toxicity was positively correlated (p<0.05 or p<0.01) with the total dose of the mixture. In general, the lesser and higher toxic effects are those of mixtures containing SIPX and PEX, respectively.

Fe(Ⅲ) ions enhanced catalytic properties of (BiO)2CO3 nanowires and mechanism study for complete degradation of xanthate

The wire-like Fe3+-doped (BiO)2CO3 photocatalyst was synthesized by a hydrothermal method. The photocatalytic property of Fe3+-doped (BiO)2CO3 nanowires was evaluated through degradation of sodium isopropyl xanthate under UV–visible light irradiation. The as-prepared Fe3+-doped (BiO)2CO3 nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) in detail. The results of XRD showed that the crystallinity of (BiO)2CO3 nanowires decreased when Fe3+ ions were introduced into the solution system. XPS results illustrated that xanthate could be absorbed on the surface of Fe3+-doped (BiO)2CO3 nanowires to produce BiS bond at the beginning of the reaction, which could broaden the visible light absorption. FTIR spectra confirmed the formation of SO42− after photocatalytic decomposition of xanthate solution. The Fe3+-doped (BiO)2CO3 nanowires showed an enhanced photocatalytic activity for decomposition of xanthate due to the narrower band gap and larger BET surface area, comparing with pure (BiO)2CO3 nanowires. By the results of UV–vis spectra of the solution and FTIR spectra of recycled Fe3+-doped (BiO)2CO3, the xanthate was oxidized completely into CO2 and SO42−. The photocatalytic degradation process of xanthate followed a pseudo-second-order kinetics model. The mechanism of enhanced photocatalytic activity was proposed as well.

Sulfur reduction in Sangan iron ore by flotation

in this study the flotation of pyrite as the main sulfide impurity of Sangan iron ore in Iran, was investigated. For this purpose the effect of collector type, pH, collector concentration and stage dosing on reverse flotation of iron sulfide ore from magnetite ore was investigated. Two type of thiol collectors include xanthates (sodium isopropyl xanthate (SIPX) and potassium amyl xanthate (PAX)) and dithiocarbamate (di-ethyl dithiocarbamate (DTC)) and the mixture of collectors was studied. The highest sulfur removal was obtained with potassium amyl xanthate. Stage dosing had a significant effect in sulfide flotation and the best recovery was obtained when the collector was added in 4 stages. The acidity had a positive effect on sulfide floatability and the best result was obtained at pH 3.5-4. Investigation about collector concentration showed that increasing the SIPX concentration enhanced the sulfur removal but this factor was not effective for PAX.

Sulfur reduction in Sangan iron ore by flotation

in this study the flotation of pyrite as the main sulfide impurity of Sangan iron ore in Iran, was investigated. For this purpose the effect of collector type, pH, collector concentration and stage dosing on reverse flotation of iron sulfide ore from magnetite ore was investigated. Two type of thiol collectors include xanthates (sodium isopropyl xanthate (SIPX) and potassium amyl xanthate (PAX)) and dithiocarbamate (di-ethyl dithiocarbamate (DTC)) and the mixture of collectors was studied. The highest sulfur removal was obtained with potassium amyl xanthate. Stage dosing had a significant effect in sulfide flotation and the best recovery was obtained when the collector was added in 4 stages. The acidity had a positive effect on sulfide floatability and the best result was obtained at pH 3.5-4. Investigation about collector concentration showed that increasing the SIPX concentration enhanced the sulfur removal but this factor was not effective for PAX.

Flotation Behavior of Complex Sulfide Ores in the Presence of Biodegradable Polymeric Depressants

In this study, chitosan polymer was tested as a potential selective green depressant of pyrite in the bulk flotation of galena (PbS) and chalcopyrite (CuFeS2) from sphalerite (ZnS) and pyrite (FeS2) using sodium isopropyl xanthate as a collector and 4-methyl-2-pentanol (MIBC) as a frother. Flotation tests were carried out in a D12-Denver flotation laboratory cell in the presence and absence of chitosan and/or sodium cyanide depressant which is commercially used as pyrite depressant in sulfide mineral flotation process. Flotation recoveries and concentrate grades (assay) were studied as a function of polymer concentration and flotation time. It was found that at 50 g/ton, chitosan depressed 5.6% more pyrite as compared to conventional depressant NaCN at its optimum dosage. Furthermore, the measured assay values of pyrite in concentrates dropped by ~1.2% when NaCN depressant was replaced with chitosan polymer. Zeta potential measurements of galena, chalcopyrite, sphalerite, and pyrite suspensions before and after chitosan’s addition revealed that the polymer has preferential adsorption on pyrite minerals as compared to other sulfide minerals specially galena. Results obtained from this work show that chitosan polymer has a promising future as a biodegradable alternative to sodium cyanide for the purpose of depressing pyrite in sulfide minerals flotation.

Investigating the effects of different collectors on sulfide minerals kinetic flotation of Miduk copper mine

Miduk has sulfide copper mine and produces copper concentrate with an alloy of more than 30 percent. Flotation tests have been conducted using Sodium isobutyl ditiophosphate collectors (A3477) and sodium isopropyl xanthate (Z11) and thionocarbamate (X231). Denver cell flotation tests in laboratory scale are performed by injecting a type of collector at a dose of 35 gram/tone. Parameters such as recovery, alloy, using mineralogy results, kinetics constant in flotation reaction were measured for sulfide copper minerals (chalcopyrite chalcosite, covellite and pyrite). By comparing and analyzing the obtained results, it was determined by that collector A3477 with kinetics constant of 1.2285 (min-1) has been more effective in floating copper and also has resulted in most alloy percentage; and with kinetic constant of 1.09878 (min-1) had the highest kinetics constant for chalcopyrite mineral; and with kinetic constant of 1.6347 (min-1 (it has been the most effective collector in floating covellite comparing to Z11 and X231. X231 collector with kinetic constant of 1.42074 (min-1) is the most effective collector in floating chalcosite mineral. Z11 collector has achieved a greater recovery of 95 percent. X231 and A3477 collectors had a better performance in pyrite abatement and have showed less selective properties toward flotation of pyrite.

Toxic effect of two kinds of mineral collectors on soil microbial richness and activity: analysis by microcalorimetry, microbial count, and enzyme activity assay.

Flotation reagents are hugely and increasingly used in mining and other industrial and economic activities from which an important part is discharged into the environment. China could be the most affected country by the resulting pollution. However, their ecotoxicological dimension is still less addressed and understood. This study aimed to analyze the toxic effect of sodium isobutyl xanthate (SIBX) and sodium isopropyl xanthate (SIPX) to soil microbial richness and activity and to make a comparison between the two compounds in regard to their effects on soil microbial and enzymes activities. Different methods, including microcalorimetry, viable cell counts, cell density, and catalase and fluorescein diacetate (FDA) hydrololase activities measurement, were applied. The two chemicals exhibited a significant inhibitory effect (P<0.05 or P<0.01) to all parameters, SIPX being more adverse than SIBX. As the doses of SIBX and SIPX increased from 5 to 300μgg-1 soil, their inhibitory ratio ranged from 4.84 to 45.16% and from 16.13 to 69.68%, respectively. All parameters fluctuated with the incubation time (10-day period). FDA hydrolysis was more directly affected but was relatively more resilient than catalase activity. Potential changes of those chemicals in the experimental media and complementarity between experimental techniques were justified.

A study on selective flotation in low and high pyritic copper sulphide ores

ABSTRACTThe effect of chemical reagent configurations was investigated on two different copper sulphide ore types, including high and low pyritic feeds. Three different combinations of collectors as isopropyl-n-ethyl thionocarbamate (C-4132), mixture of mercaptobenzothiazole and butyl sodium dithiphosphate (Flomin 7240) and sodium isopropyl xanthate (Z11) were used in flotation experiments. Solely using C-4132 was selected as the best pattern for both feed types with regard to achieving the highest copper grade and the lowest iron recovery. However, the selectivity index (SI) results showed that the combination of Z11+F7240 provides the highest selectivity of chalcopyrite against pyrite in either low or high pyritic ores.

Recovery improvement of coarse particles by stage addition of reagents in industrial copper flotation circuit

ABSTRACTObtaining high recovery in coarse particle size fractions has been always under investigation in recent years. In the present study, stage addition of chemical reagents is used to improve copper grade and recovery of coarse size fractions (i.e., >100 µm) at industrial rougher flotation cells. Due to the poor efficiency of primary grinding circuit, coarse particles were detected as predominate size fraction in rougher flotation feed. Sampling results from rougher tailings showed that 58% of precious copper minerals were distributed to size fraction of −105 + 297 µm. Stage addition of collectors including sodium isopropyl xanthate (Z11), dithiophosphate and mercaptobenzthiazole (Nascol-451), and xanthate-flomin (C-4132) and frothers as methyl isobutyl carbonyl (MIBC) and Aerofroth 65 (A65) were implemented to avoid losing of coarse valuable particles in rougher tailings. Three different patterns were given for stage additions as 75-25-0, 75-0-25, and 75-13-12. The results indicated that copper grade of tailings declined relatively 56% using optimized stage addition of reagents at the head of rougher banks (i.e., 75-13-12). In addition, copper recovery of rougher cells improved around 2%. Size by size analysis of copper recovery for the rougher cells revealed the significant effect of the stage addition of chemical reagents on recovery improvement of coarse particles.

Enhanced UV–visible response of bismuth subcarbonate nanowires for degradation of xanthate and photocatalytic reaction mechanism

(BiO)2CO3 nanowires were prepared by simple hydrothermal treatment of commercial Bi2O3 powders and characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of (BiO)2CO3 nanowires was studied through degradation of sodium isopropyl xanthate. Photocatalytic experimental results indicated that the as-prepared (BiO)2CO3 nanowires show high photocatalytic efficiency. Photocatalytic activity increased after two cycles. Time-dependent UV–vis spectra demonstrated that the final degradation products included isopropyl alcohol and carbon disulfide. UV–vis diffuse reflection spectra showed that the band gap of the as-prepared (BiO)2CO3 nanowires and recycled (BiO)2CO3 nanowires were 2.75 eV and 1.15 eV, respectively. XPS results indicated that formation of Bi2S3@(BiO)2CO3 core–shell nanowires occurred after recycled photodegradation of isopropyl xanthate owing to existence of two types of Bi configurations in the recycled (BiO)2CO3 nanowires. A probable degradation mechanism of isopropyl xanthate was also proposed.