Search Results (1,271)

Phosphogypsum is an industrial byproduct that is limited in its high-value application due to the presence of dyeing impurities (such as organic matter and carbon black). The flotation method has been verified to be effective in separating these dyeing impurities from gypsum. In this study, microemulsion was used as the collector method of dyeing impurities for their separation from gypsum. The results of flotation tests showed that the microemulsion collector exhibited excellent collection capability and selectivity under natural pH conditions (pH = 1.5). With a microemulsion collector consumption of 400 g/t, purified gypsum of 65.1% whiteness, 95.74% yield, and 97.01% recovery was obtained. The purified gypsum of 65.1% whiteness, 95.74% yield, 97.01 recovery obtained by a used microemulsion collector amount of 400 g/t was better than using the same dosage of kerosene collector. The dispersion behavior of the microemulsion collector was studied by low-temperature transmission electron microscopy. The microemulsion collector demonstrated superior dispersibility, as it forms nano-oil droplets with an average size of 176.83 nm in the pulp, resolving issues associated with poor dispersibility observed in traditional kerosene collectors. Additionally, the nano-oil droplets effectively adsorbed onto the surface of dyeing impurities through hydrogen bonding, enhancing their hydrophobicity. Therefore, the microemulsion collector holds great potential for application in flotation whitening processes involving phosphogypsum. Full article

The efficient recovery of fine argentite from polymetallic lead–zinc (Pb–Zn) sulfide ore is challenging. This study investigated nanobubble (NB) adsorption on the argentite surface and its role in enhancing fine argentite flotation using various analytical techniques, including contact angle measurements, adsorption capacity analysis, infrared spectroscopy, zeta potential measurements, turbidity tests, microscopic imaging, scanning electron microscopy, and flotation experiments. Results indicated that the NBs exhibited long-term stability and were adsorbed onto the argentite surface, thereby enhancing surface hydrophobicity, reducing electrostatic repulsion between fine argentite particles, and promoting particle agglomeration. Furthermore, the NBs formed a thin film on the argentite surface, which decreased the adsorption of sodium diethyldithiocarbamate. Microflotation tests confirmed that the introduction of NBs considerably enhanced the recovery of argentite using flotation technology. Full article

The growing demand for metal production promotes the search for alternative sources and novel modalities in metallurgy. Flotation tailings are an important secondary mineral resource; however, they might pose a potential environmental threat due to containing toxic metals. Therefore, proper leaching reagent selection is required. Ozone is an alternative oxidizing agent for metal leaching, as its use prevents contaminating product generation while increasing the noble metal extraction efficiency in the presence of complexing agents. In this study, the feasibility and efficiency of combining the use of thiosulfate and ozone for gold and silver extraction have been investigated as an eco-friendly alternative for recovery from flotation tailings. Two sets of samples from old flotation tailings of Copper Mine Bor (Serbia) were prepared and physico-chemically characterized, then treated in two experimental leaching procedures, followed by thorough XRD and SEM/EDS analyses of the products. It showed that after 1 h of leaching in a water medium at room temperature and a solid-to-liquid phase ratio of 1:4, 88.8% of Cu was obtained, while a high efficiency of Au extraction from solid residue (after Cu leaching) was attained (83.4%). The results suggest that ozone-assisted leaching mediated by Ca-thiosulfate can be an effective eco-friendly treatment for noble metals recovery from sulfide-oxide ores. Full article

The pyridinium phenolate punicine is a switchable molecule from Punica granatum. Depending on the pH, punicine exists as a cation, neutral molecule, anion, or dianion. In addition, punicine reacts to light, under the influence of which it forms radical species. We report on three punicine derivatives that possess an adamantyl, 2-methylnonyl, or heptadecyl substituent and on their performance in the flotation of lithium aluminate, an engineered artificial mineral (EnAM) for the recycling of lithium, e.g., from lithium-ion batteries. By optimizing the parameters: pH and light conditions (daylight, darkness), recovery rates of 92% of LiAlO₂ are achieved. In all cases, the flotation of the gangue material gehlenite (Ca₂Al[AlSiO₇]) is suppressed. IR, the contact angle, zeta potential measurements, TG-MS, and PXRD confirm that the punicines interact with the surface of LiAlO₂, which is covered by LiAl₂(OH)₇ after contact to water, resulting in a hydrophobization of the particle. The plasma pretreatment of the lithium aluminate has a significant influence on the flotation results and increases the recovery rates of lithium aluminate in blank tests by 58%. The oxidative plasma leads to a partial dehydratisation of the LiAl₂(OH)₇ and thus to a hydrophobization of the particles, while a reductive plasma causes a more hydrophilic particle surface. Full article

Lithium-ion batteries with an LFP cell chemistry are experiencing strong growth in the global battery market. Consequently, a process concept has been developed to recycle and recover critical raw materials, particularly graphite and lithium. The developed process concept consists of a thermal pretreatment to remove organic solvents and binders, flotation for anode–cathode separation, and hydrometallurgical processes for product recovery. It has been shown that a pretreatment step is necessary for efficient flotation. By increasing the thermal treatment temperatures up to 450 °C, recovery rates of up to 73% are achieved. Similar positive effects are observed with leaching, where leaching efficiencies increase with higher treatment temperatures up to 400 °C. The results indicate that the thermal treatment of the black mass significantly influences both flotation and hydrometallurgical processes. Full article

This study examined the appropriate hematite (Fe₂O₃) collector for the concentration of pyrolusite (MnO₂) in a reverse flotation. Actual ore flotation studies were performed to determine how sodium oleate, sodium dodecyl sulfonate, and oxidized paraffin soap affect hematite removal during reverse flotation of pyrolusite ore. In order to explore the flotation mechanism, simulation experiments were carried out. Firstly, the crystal models of pyrolusite and hematite were established. Then, in order to verify the reliability of the simulation results, the simulated XRD spectra of the crystal model were compared with the measured spectra. Finally, density functional theory and molecular dynamics modeling were used to study the interaction between collector molecules and mineral surfaces. The flotation test results show that oxidized paraffin soap is the best hematite collector and promotes its flotation, removing iron from pyrolusite. Molecular dynamics simulations and density functional theory show that the three collectors (oxidized paraffin soap, sodium oleate, and sodium dodecyl sulfonate) have a much stronger interaction with hematite than with pyrolusite. Therefore, it is possible to separate pyrolusite and hematite through flotation. The simulation results also show that oxidized paraffin soap has the highest adsorption strength and selectivity for hematite. This characteristic makes oxidized paraffin soap an excellent collector for effectively removing hematite from pyrolusite in the reverse flotation process. Full article

This paper evaluates the performance of four ethoxylated nonionic surfactants (nonyl phenol vs. C₁₃ alcohols) to act as ancillary collectors with Alkyl Amidoamine (AAA) in the reverse flotation of quartz at pH8 to concentrate iron ores. Compared to 100% AAA, the blend composed of 80% AAA (Flotinor^®5530) plus 20% of isotridecyl alcohol ethoxylated with five groups of ethylene oxide (DP-210 RO) improved quartz recovery (from 54% to 63%, p < 0.05) by increasing contact angle (from 55° to 56°, p < 0.05) and decreasing induction time (26 ms to 23 ms, p < 0.05). Compared to 100% AAA (200 g/t), the blend (160 g/t of AAA + 40 g/t of DP-210 RO) improved the flotation performance of iron ore, yielding richer hematite concentrate (65.3% Fe × 61.4% Fe) and less contaminated with quartz (4% SiO₂ × 10.2% SiO₂), coupled with an increase in Fe recovery from 79.8% × 81.6% in the sunken product as well as SiO₂ recovery from 91.7% to 96.9% in the froth. Results from zeta potential, the hydrodynamic diameter of reagent droplets, and the surface tension of the solution provide insights into the synergism between AAA and DP-210 RO. Full article

CuS nanoparticles (Np) were synthesized and deposited on synthetic sphalerite (S_P) using two different methods. Two nanoparticle products were obtained on the surface of S_P, Np1 and Np2, resulting in two active materials (Np1-S_P and Np2-S_P) with specific characteristics. Nanoparticles and active materials were characterized by TEM, XRD, SEM, and XPS. The collectors PAX and SIPX were adsorbed on Np1-S_P and Np2-S_P to determine the adsorption capacity. Method 1 provides a higher quantity of nanoparticles on S_P, which allows for the adsorption of a higher amount of SIPX. Method 1 was used to deposit nanoparticles on two natural sphalerites (S_N) with different iron contents. S_N, unlike S_P, can be used to test nanoparticle activation results in microflotation experiments. S_N was activated with nanoparticles (Np1-S_N) and using the traditional method (Cu-S_N). The recovery of 75% of zinc using the microflotation process suggests that the hydrophobicity of Np1-S_N is higher than that of Cu-S_N. Nanoparticles improve the hydrophobicity of S_N compared to the traditional activation used in the mining industry. These results suggest that using nanoparticles is an excellent option to activate minerals in flotation processes, decreasing the consumption of reagents and helping to mitigate negative impacts on the environment. Full article

The increasing demand for zinc resources and the declining availability of sulfide zinc ore reserves have made the efficient utilization of zinc oxide a topic of considerable interest. In this study, a ternary composite collector ABN (Al-BHA-NaOL system) was applied to the direct flotation of smithsonite. Micro-flotation studies showed that at pH 9, ABN exhibited better adsorption on smithsonite, achieving a recovery rate of 80.62%. Visual MINTEQ 3.1 and zeta potential analysis confirmed that ABN predominantly reacted with Zn(OH)₂(aq) on the surface of smithsonite. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis results elucidated the formation of Al-O bonds through chemical adsorption on the smithsonite surface. Additionally, powder contact angle measurements indicated that ABN enhances the surface contact angle of smithsonite. These results illuminate that ABN is adsorbed by reacting with O sites on hydroxylated metal ions on the smithsonite surface, with Al serving as the adsorption center, thereby achieving separation and purification. Due to ABN’s adsorption characteristics, smithsonite can achieve efficient and clean direct flotation recovery without sulfidization. Full article

The order Passeriformes is the richest and most abundant group of birds, but despite numerous parasites being identified in wild birds, this order has received limited focus. This study analyzed 17 passerines admitted to the Grupo de Rehabilitación de la Fauna Autóctona y su Hábitat (GREFA), a wildlife rehabilitation center in Spain, during October to December 2022. Necropsies were conducted to determine the presence of parasites, and intestinal contents were analyzed using fecal smear, flotation and sedimentation techniques and the McMaster method. Sixteen passerines (94.1%) were positive for parasites. Identified species included Monojoubertia microhylla and the genera Ornithonyssus sp., Diplotriaena spp., Serratospiculum sp., Porrocaecum sp., Capillaria spp., Syngamus sp., Strongyloides sp. and Brachylecithum sp., besides cestodes and coccidia. The comparative analysis of parasitological diagnostic techniques showed that the Willis flotation technique was effective for detecting coccidia. However, to obtain more accurate results for other parasites, it is important to complement this technique with direct examination or sedimentation techniques. Among the 12 passerines positive for coccidia, oocyst counts per gram of intestinal contents ranged from 100 to 30,450, with a median of 7350. This study provides valuable insights into the parasitic fauna of Passeriformes, serving as a cornerstone for future research and enhancing our understanding of these avian species. Full article

Composite materials based on diatomite (DT) with the addition of biochar (BC), dolomite (DL), and bentonite (BN) were developed. The effect of chemical modification on the chemical structure of the resulting composites was investigated, and their influence on heavy metal immobilization and the ecotoxicity of post-flotation sediments was evaluated. It was demonstrated that the chemical modifications resulted in notable alterations to the chemical properties of the composites compared to pure DT and mixtures of DT with BC, DL, and BN. An increase in negative charge was observed in all variants. The addition of BC introduced valuable chemically and thermally resistant organic components into the composite. Among the chemical modifications, composites with the addition of perlite exhibited the lowest values of negative surface charge, which was attributed to the dissolution and transformation of silicon compounds and traces of kaolinite during their initial etching with sodium hydroxide. The materials exhibited varying efficiencies in metal immobilization, which is determined by both the type of DT additive and the type of chemical modification applied. The greatest efficacy in reducing the mobility of heavy metals was observed in the PFS with the addition of DT and BC without modification and with the addition of DT and BC after the modification of H₂SO₄ and H₂O₂: Cd 8% and 6%; Cr 71% and 69%; Cu 12% and 14%; Ni 10% and Zn 15%; and 4% and 5%. In addition, for Zn and Pb, good efficacy in reducing the content of mobile forms of these elements was observed for DT and DL without appropriate modification: 4% and 20%. The highest reduction in ecotoxicity was observed in the PFS with the addition of DT and BC, followed by BN and DL, which demonstrated comparable efficacy to materials with DT and BN. Full article

Diamond wire saw silicon slurry (DWSSS) is a waste resource produced during the process of solar-grade silicon wafer preparation with diamond wire sawing. The DWSSS contains 6N grade high-purity silicon and offers a promising resource for high-purity silicon recycling. The current process for silicon extraction recovery from DWSSS presents the disadvantages of lower recovery and secondary pollution. This study focuses on the original DWSSS as the target and proposes flotation for efficiently extracting silicon. The experimental results indicate that the maximal recovery of silicon reached 98.2% under the condition of a dodecylamine (DDA) dosage of 0.6 g·L⁻¹ and natural pH conditions within 24 min, and the flotation conforms to the first-order rate model. Moreover, the mechanism of the interface behavior between DWSSS and DDA revealed that DDA is adsorbed on the surface of silicon though adsorption, and the floatability of silicon is improved. The DFT calculation indicates that DDA can be spontaneously adsorbed with the silicon. The present study demonstrates that flotation is an efficient method for extracting silicon from DWSSS and provides an available option for silicon recovery. Full article

Copper flotation tailings (FTs), resulting from the separation and beneficiation processes of ores, are a significant source of environmental pollution (acid mine drainage, toxic elements leaching, and dust generation). The most common disposal method for this industrial waste is dumping. However, due to their favorable physical and chemical properties—the high content of aluminosilicate minerals (60–90%)—flotation tailings can be effectively treated and reused through geopolymerization technology, thereby adding value to this waste. The objective of this study was to evaluate the potential of utilizing the geopolymerization of FTs to produce sustainable materials. Geopolymers based on natural zeolite (NZ), sodium-modified natural zeolite (NaZ), and fly ash (FA) were prepared using 20%, 35%, and 50% of FTs, activated with a 10 M NaOH solution. The study investigated the influence of Ca/Si, Si/Al, and Na/Al molar ratios on the structural, thermal, and mechanical properties (XRD, TG/DTG and unconfined compressive strength, UCS), and contaminant immobilization (TCLP method) of geopolymers. Geochemical modeling via the PHREEQC program was employed to interpret the results. The findings indicated that the UCS value decreased in zeolite-based geopolymers as the content of FT increased due to the inertness of the tailings and the low calcium content in the system (Ca/Si ≤ 0.3), in contrast to the FA-based geopolymer. The highest UCS of 44.3 MPa was recorded in an FA-based geopolymer containing 50% flotation tailings, with optimal molar ratios of 0.4 for Ca/Si, 3.0 for Si/Al, and 1.1 for Na/Al. In conclusion, the geopolymerization process has been determined to be a suitable technological approach for the sustainable treatment and reuse of FTs. Full article

Sphalerite flotation is generally achieved by copper activation followed by xanthate collection. This study aims to propose a design idea to find novel collectors from the perspective of molecular design and prove the theoretical feasibility that the collector can effectively recover sphalerite without copper activation. To address this, 30 compounds containing different structures of sulfur atoms and different neighboring atoms were designed based on coordination chemistry. Twelve potential collectors were screened, and their properties and interactions with a hydrated sphalerite (110) surface were evaluated. Compound 27 (C₂H₄S₂²⁻) showed the greatest reactivity, suggesting that the double-coordination structure of two sulfhydryl groups is an effective molecular structure for direct sphalerite flotation. The DFTB+ and MD results demonstrate that 1,2-butanedithiol (C₄H₁₀S₂), having a similar coordination structure to compound 27, has the potential to replace the traditional reagent scheme of sphalerite flotation. The strong reagent–surface interaction is attributed to the overlap of Zn 3d with S 3p orbitals, the most negative electrostatic potential, the relatively high E_HOMO and low average local ionization energy, and the eliminated steric hindrance effect. It is expected that this study can provide a design idea for the targeted design and development of novel reagents for complex sulfide ore flotation. Full article

The significance of the roughness of particles in flotation has been recognized for several decades. In this study, to investigate the effect of particle roughness, a series of rod milling with different grinding durations is performed on the quartz particles. Subsequently, the particle roundness, wetting rate, and floatability are measured. Finally, the flotation kinetic experiments are conducted based on a fixed particle size, and the interaction energy between rough particles and bubbles is calculated based on extended DLVO (E-DLVO) theory. Results show that by increasing the grinding time, the hydrophobic particle surface roughness increases, and the improved flotation rate constant increases. While the results of the E-DLVO calculation show that the interaction energy barrier between particles and bubbles decreases significantly as the roughness increases, the theoretical calculation and the experimental results confirm that an increase in the particle surface roughness decreases the interaction energy barrier between particle bubbles and increases the flotation rate. Full article