Cassiterite Flotation Research Articles

The application and adsorption selectivity of a novel collector 4-butoxy-N-hydroxybenzamide in cassiterite flotation

In cassiterite flotation, the superior selectivity of benzohydroxamic acid (BHA) leads to its common use as a collector. However, its weak collecting ability necessitates the synthesis of 4-butoxy-N-hydroxybenzamide (BHBA) by introducing a butoxy group at the para-position of the N-hydroxyamide group in BHA molecular structure. BHBA, when functioning as a collector in the flotation separation of cassiterite and calcite, retains BHA selectivity while enhancing its collecting ability. Zeta potential experiments show that under same reagent dosage and slurry pH conditions, BHBA is adsorbed in larger amounts on cassiterite surface than on calcite, conferring its stronger collecting ability in cassiterite flotation. X-ray photoelectron spectroscopy reveals that BHBA donates more electrons to Sn4+ ions on cassiterite surface versus Ca2+ ions on calcite surface, resulting in the intensified adsorption affinity of BHBA on cassiterite. First-principles calculations indicate that BHBA achieves higher recoveries of cassiterite relative to BHA, attributed to its longer hydrophobic carbon chain and the electron-donating nature of the butoxy group, which enhances the reactivity of the N-hydroxy amide group in BHBA.

Sodium dodecyl benzene sulfonate as a new ligand to enhance the flotation of cassiterite in Pb-BHA system

As high-quality cassiterite resources dwindle, the significance of cassiterite associated with scheelite escalates. In this study, we synthesized a novel lead-group double ligand collector (Pb-BHA-SDBS) by introducing a new ligand, sodium dodecyl benzene sulfonate (SDBS), into the structure of lead complexes of benzohydroxamic acid (Pb-BHA). The flotation performance of Pb-BHA-SDBS was investigated by single-mineral flotation. The structural and chemical properties of Pb-BHA-SDBS were systematically investigated through FTIR, XPS, and quantum chemical calculations. The mechanism of enhancing cassiterite flotation with Pb-BHA-SDBS were investigated through adsorption energy analysis, XPS, AFM and contact angle analysis. The flotation recovery of cassiterite greatly increased from ≤30 % to ≥80 % when the Pb-BHA-SDBS is utilized as the collector. The FTIR and XPS results indicated that both SDBS and BHA form coordination bonds with lead ions, significantly strengthening the adsorption ability on the cassiterite surface. The adsorption of Pb-BHA-SDBS on the surface of cassiterite forms larger colloidal aggregates, further enhancing the roughness and hydrophobicity of the cassiterite surface, thereby strengthening the flotation of cassiterite.

A novel combined collector for high-performance flotation of cassiterite: Experimental insights and MD simulations

Collectors are critical in the flotation and separation of fine-grained minerals. In this study, a new combined collector, namely phosphoric acid (SPA)/dodecylbenzene sulfonate isopropanolamine (DBIA) was prepared via self-assembly. First, the flotation of cassiterite was investigated using SPA and DBIA separately, and the micro-collection mechanism of these single-material collectors on the surface of cassiterite was clarified by density functional theory calculations. Then, combined SPA/DBIA collectors were prepared, and the effect of the SPA/DBIA molar mass ratio on cassiterite flotation performance was studied. Surface tension measurements and molecular dynamics (MD) simulations were used to investigate the gas–liquid interfacial self-assembly of the SPA/DBIA collector. Subsequently, the flotation separation behavior of SPA/DBIA on the solid–liquid–gas interface was experimentally evaluated, and the adsorption mechanism of this combined collector at the three-phase interface was comprehensively investigated by performing MD simulations. The results show that SPA/DBIA combined collectors can obtain 80.88 % cassiterite flotation recovery at 1.2 × 10−4 mol/L. The addition of SPA led to the continuous adsorption of DBIA on the surface of cassiterite, forming a more stable and dense adsorption film. The mass density of the adsorption film was 319.27 ng/cm2, owing to the synergistic co-adsorption. Finally, the surface of the cassiterite was modified to enhance its hydrophobicity. This work demonstrates the application of collector self-assembly to improve the recovery of fine-grained cassiterite via flotation.

5-Dodecylsalicylaldoxime as a Novel Collector in Cassiterite Flotation: Performance and Mechanism

Hydroxamic acid and fatty acid collectors are commonly used in cassiterite flotation but face issues like poor selectivity, high dosage, and strict requirements on ore composition and grinding fineness. This study investigates the collecting performance of a novel flotation reagent, 5-dodecylsalicylaldoxime (DSA), in cassiterite flotation. DSA exhibits remarkable selectivity, achieving an impressive 82.5% recovery of Sn at a concentration of only 9 × 10−5 mol/L in single mineral flotation tests. Moreover, DSA significantly outperforms benzohydroxamic acid (BHA), enhancing Sn recovery by 33.55% in artificially mixed ore flotation experiments. In the flotation test of a copper–tin polymetallic ore, compared with the BHA flotation effect, the recovery rate of DSA increased by 12.29% when the Sn grade remained basically unchanged. Analyses such as zeta potential, FT-IR, and XPS indicate that DSA’s superior collecting performance stems from its stable adsorption onto cassiterite surfaces through a chelating ring formation, resembling the adsorption mechanism of hydroxamic acid collectors. Furthermore, DSA’s larger cluster size in the solution compared to BHA contributes to its enhanced selectivity and collectability. Overall, DSA emerges as a promising alternative to traditional cassiterite flotation collectors, offering a combination of enhanced selectivity, lower dosage requirements, and robustness in complex ore systems.

Experimental and MD study on the effect of SDS/OHA mixed collector co-adsorption on cassiterite flotation

The use of assorted collectors for cassiterite flotation demonstrated good results. However, enhancing the process efficiency and reducing the associated costs for a practical application remains. In this study, micro-flotation experiments were conducted to examine the floatability of cassiterite upon reaction with a single collector, that is, octyl hydroxamic acid (OHA) or sodium dodecyl sulfonate (SDS), or with a mixed collector OHA/SDS, and the molar ratio of the two collectors to cassiterite flotation was determined. The positive synergy between the two collectors was confirmed using surface tension calculations. The zeta potential, adsorption, and XPS demonstrated that the co-adsorption of mixed collectors on the surface of cassiterite was more robust than that of a single collector. Atomic force microscopy (AFM) was used to identify the morphology of the adsorption of flotation reagents on the cassiterite surface. According to the AFM observations, the mixed collector exhibited spot and layered adsorption on the surface of cassiterite, suggesting co-adsorption of the mixed collector on the mineral surface. Molecular dynamics (MD) simulations demonstrated that the relative concentration of water in the hydration film on the cassiterite surface decreased significantly after the action of the SDS/OHA mixed collector, and the cassiterite surface presented a stronger hydrophobicity.

Adsorption of salicyl hydroxamic acid and octyl hydroxamic acid mixture on the cassiterite minerals

Salicylhydroxamic acid (SHA) and octyl hydroxamic acid (OHA) are two commonly used hydroxamic acid-based collectors in fine cassiterite flotation. While some reports suggest that a mixture of OHA and SHA yields superior results compared to their individual use, there is a lack of experimental exploration and theoretical analysis. In this study, the flotation performance and the associated adsorption mechanism of SHA, OHA and their mixture on fine cassiterite particles was systematically investigated. The results demonstrate a synergistic effect between SHA and OHA in enhancing fine cassiterite flotation, with the most significant enhancement occurring at a 1:1 mass ratio under the natural pH conditions. This finding is corroborated by contact angle and zeta potential tests. When both SHA and OHA are present, SHA likely attaches to the cassiterite surface via chemisorption in the form of a five-membered chelate ring, while OHA adheres through physical adsorption, primarily establishing hydrogen bonds with oxygen sites on the cassiterite surface or with SHA molecules. The adsorption ratio of SHA to OHA onto cassiterite surfaces is approximately 69%: 31% when an equal mass of SHA and OHA interact with cassiterite under the natural pH condition.

An insight into fine cassiterite recovery: A novel surfactant-phenylpropylhydroxamic acid and its adsorption mechanism

The effective recovery of fine-grained cassiterite is a difficult problem in tin ore beneficiation. For enhancing the performance of the traditional collector for fine cassiterite flotation, a novel surfactant phenyl propyl hydroxamic acid (PHA) was designed by introducing one ethyl group (–CH2-CH2-) into benzohydroxamic acid (BHA).The study of flotation properties and the adsorption mechanism of PHA onto cassiterite surface were systematically investigated by scanning electron microscopy-energy dispersive X-ray spectroscopy testing (SEM-EDS), adsorption measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Density functional theory (DFT). The results indicate that PHA has an excellent flotation performance for fine cassiterite compared with BHA and salicylhydroxamic acid (SHA), and the interaction between PHA and the surface of mineral mainly exhibited chemisorption attributed to new Sn-O chemical bonds. Meanwhile, DFT calculations showed that PHA adsorbed on the cassiterite surface via chelating interaction by the formation of a five-membered chelate ring.

Selective Separation Behavior and Study on the Interaction Mechanism of 2-Hydroxy-3-Naphthylmethyl Hydroxamic Acid and Cassiterite

In this study, the performance of 2-hydroxy-3-naphthylmethyl hydroxamic acid (NHA) in cassiterite flotation was investigated. The aim was to understand the mechanism of action of NHA for the first time. The effect of NHA as a collector in the flotation separation of cassiterite, calcite, and quartz was investigated via microbubble flotation experiments. The experimental results showed that the maximum recovery of cassiterite in the presence of NHA was 91.76%. This was attributed to the selective adsorption of NHA on the cassiterite surface. NHA showed a stronger collection performance for cassiterite than calcite and quartz. Therefore, the mechanism of NHA-cassiterite interaction was investigated using zeta potential, the logarithmic solubility plot (LSD), Fourier Transform Infrared (FT-IR), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscope (SEM) analyses. This study introduces a new adsorption process and mechanism for the NHA-based adsorption of cassiterite. The results show that, under neutral conditions, the solute components of cassiterite surface lattice ions mainly exist in the form of Sn–OH complexes. Chemisorption occurs between cassiterite and NHA which is adsorbed onto the cassiterite surfaces through interaction with O sites, rather than Sn sites as is traditionally expected. Further, the hydroxyl and hydroxyl groups of NHA are chemically coordinated with Sn–OH on the surface of cassiterite to form a six-membered chelate ring. This proposed mechanism can be extended to most systems in which metal ions interact with hydroxamic acids bearing hydroxyl groups. This contributes to a better understanding of the activation mechanism of hydroxamic acid collectors in cassiterite flotation.

Comparing cyclohexyl hydroxamic acid and benzohydroxamic acid in cassiterite flotation under lead nitrate activation

This paper investigates the flotation behavior of Cyclohexyl hydroxamic acid (CHA) and benzhydroxamic acid (BHA) on cassiterite under lead nitrate activation conditions and elucidates the adsorption mechanism of CHA on the cassiterite surface. Microflotation experiments were performed to compare the capturing efficiency of CHA and BHA at pH values ranging from 4 to 12. Results showed that CHA exhibited superior capability in capturing cassiterite compared to BHA. The recovery of cassiterite in the hydroxamic acid-based flotation system correlated positively with the adsorption of hydroxamic acid on the cassiterite surface. Adsorption experiments revealed an increase in adsorption quantity with an increase in hydroxamic acid dosage, with CHA exhibiting significantly higher adsorption amount than BHA on the cassiterite surface. To analyze the adsorption mechanism of CHA on the cassiterite surface, both infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis were conducted, both before and after lead nitrate activation. IR spectra and XPS results indicated that lead ion activation enhanced the adsorption of CHA on the cassiterite surface, resulting in an increased number of active sites for CHA interaction. Additionally, chemisorption of CHA occurred on the cassiterite surface.

Synthesis of modified polystyrene nanoparticles and their application in fine cassiterite flotation

To solve the problem of the low flotation efficiency of fine cassiterite, we synthesised a novel high-efficiency collector comprising modified polystyrene nanoparticles (MPNs) by introducing 2-butenohydroxamic acid in emulsion polymerization. The particle size, surface potential, chemical structure and surface morphology of the collector were studied. The results showed that the collector comprised 20–100 nm cationic spherical nanoparticles with hydroxamic acid groups on the surface. The pure mineral micro-flotation experiment results revealed that fine cassiterite and calcite can be effectively separated using the MPNs as collector, which indicates the collecting capability and selectivity of MPNs for cassiterite. The selective adsorption mechanism of MPNs on the surface of cassiterite was further confirmed through Fourier transform infrared spectroscopy, zeta potential and scanning electron microscopy analysis.

DHX collector for recovery of cassiterite: Mechanistic insights and practical implications

This study addresses the efficiency and sustainability of tin resource utilization by exploring a novel collector, C16H33NO2 (DHX), in cassiterite flotation. DHX demonstrated superior collection efficiency and a broader effective pH range in micro-flotation tests. A peak cassiterite recovery of 92.2% was achieved with DHX at pH 7.5 ± 0.3, while BHA could achieve only 69.6%. Furthermore, DHX consistently maintained a recovery above 70% in a wide pH range from 3 to 11. The capacity of DHX to separate cassiterite from calcite in mixtures underlines its remarkable selectivity. Zeta potential and contact angle measurements showed strong DHX adsorption on cassiterite surfaces, leading to marked enhancements in hydrophobicity and potentially augmenting flotation efficiency. FTIR and XPS analyses further confirmed the formation of a stable ring structure between the hydroxy and oxime groups in DHX anions and Sn ions on the cassiterite surface. In practical applications, such as a copper-zinc-tin polymetallic mine in Yunnan, China, DHX exhibited promising recovery results in gravity separation tailings. Bench-scale flotation tests on tin-bearing tailings (0.21% Sn) resulted in a concentrate with a tin grade and recovery rate of 2.15% and 61.27%, respectively. These results highlight DHX’s immense potential as a cassiterite flotation collector, outperforming conventional alternatives in performance.

Utilization of EDTMPA as an eco-friendly depressant for selective flotation separation of cassiterite from calcite in the oleate system

In this study, the flotation tests revealed that ethylenediamine tetramethylenephosphonic acid (EDTMPA) as a calcite inhibitor has a stronger depression effect than EDTA (ethylene diamine tetraacetic acid) in the cassiterite flotation process, and the selective depression mechanism of EDTMPA was revealed by zeta potential test, TOC test, XPS analysis and DFT calculation. The flotation test results showed that effective separation of cassiterite and calcite could be achieved at pulp pH of 9.0, NaOL concentration of 1.80 × 10−4 mol/L and EDTMPA concentration of 1.25 × 10−5 mol/L. The selective adsorption of EDTMPA on the calcite surface was ascribed to the strong interactions between the phosphate ions in the former, and the surface Ca2+ ions on the latter’s crystal lattice. DFT calculations also confirmed the strong affinity of EDTMPA for calcite and its weak affinity for cassiterite. The results of this study provide an experimental and theoretical background for the sustainable and eco-friendly separation of cassiterite from calcite.

Preparation of a novel surfactant dibutyl (2-(hydroxyamino)-2-oxoethyl) phosphonate and its adsorption mechanism in cassiterite flotation

Preparation of a novel surfactant dibutyl (2-(hydroxyamino)-2-oxoethyl) phosphonate and its adsorption mechanism in cassiterite flotation

Sodium Lauroyl Glutamate as a Collector in Cassiterite Flotation

In this paper, sodium lauroyl glutamate (SLG), a stable and inexpensive green surfactant, was used as a flotation collector for the first time in cassiterite flotation. The micro-flotation tests revealed that SLG could effectively collect cassiterite and have superior selectivity against quartz over a wide pH range, compared with benzohydroxamic acid (BHA). The maximum recovery of cassiterite in the presence of SLG was 93.2%, while the quartz recovery was consistently lower than 8%. The adsorption experiments and zeta potential measurements suggested SLG was chemisorbed onto the cassiterite surface. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that the polar groups of SLG anions (the carboxyl and amide groups) chelate with the Sn ions on the cassiterite surface to form five-membered rings. This structure made SLG attach firmly to the cassiterite surface, effectively recovering cassiterite. Lastly, a good flotation index was achieved in the bench-scale flotation tests using SLG as the collector, which confirmed its potential economic value in practical application.

Mechanism of HCA and CEPPA in flotation separation of cassiterite and fluorite

As an essential raw material for the tin industry, cassiterite ore needs to be effectively separated and purified, and the removal of impurities such as fluorite becomes the key to cassiterite flotation. In this study, the flotation separation of cassiterite (SnO2) and fluorite (CaF2) was enhanced by using hydroxylcitric acid (HCA) as fluorite inhibitor and 2-carboxyphenyl phosphonic acid (CEPPA) as collector. With a reagent scheme of 120 mg/L CEPPA and 4.5 mg/L HCA at pH 10.0, the flotation recovery of cassiterite and fluorite was 92.80% and 13.57%, respectively. Under the same experimental conditions of artificially mixed mineral flotation, the flotation index of cassiterite concentrate grade 78.19% and recovery 90.29% was obtained. The selective adsorption mechanism of CEPPA and HCA on minerals was investigated by Zeta potential, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that CEPPA anions had chemically adsorbed on cassiterite and fluorite, and the adsorption of HCA on fluorite surface was stronger than that on cassiterite surface. XPS analyses further confirmed that Ca sites exposed on fluorite had a stronger affinity for HCA than cassiterite. Furthermore, the addition of HCA had little effect on the adsorption of CEPPA on cassiterite, while the strong chemisorption of HCA on fluorite surface prevented the adsorption of CEPPA on fluorite. These results provide a theoretical basis and promising new strategy for the flotation separation of cassiterite and fluorite.

Revealing the role of dithiocarbamate ester group in hydroxamic acid flotation of cassiterite with in situ AFM, DFT and XPS

To explore the role of dithiocarbamate ester group in hydroxamic acid flotation of cassiterite, a special surfactant S-[(3-hydroxyamino)-propoxy]-N-octyl dithiocarbamate (DTCHA) was designed. With carbon disulfide, octylamine, methyl acrylate and hydroxylamine as raw materials, DTCHA was facilely synthesized by a “one-pot” approach. In situ AFM (atomic force microscopy) clearly captured DTCHA aggregates self-assembled on cassiterite, which significantly increased its surface hydrophobicity. DFT (density functional theory) calculation predicted that the dithiocarbamate ester group possessed the ability of electron-donating and electrostatic interaction, and might be the second reactive center of DTCHA. XPS (X-ray photoelectron spectroscopy) and FTIR (Fourier transform infrared spectra) allowed to infer a bonding interaction between DTCHA’s dithiocarbamate with Sn during DTCHA reaction with Sn(Ⅳ) ions in aqueous solutions, while that with surface Sn(Ⅳ) atoms of cassiterite wasn’t concluded. The attendance of the dithiocarbamate hardly weakened the flotation selectivity of DTCHA against calcite, while its hydrophobization towards cassiterite became much stronger. Thus, DTCHA possessed the stronger collecting power and better selectivity for flotation separation of cassiterite from calcite than octyl hydroxamic acid. Revealing the role of DTCHA’s dithiocarbamate as a hydrophobic group in cassiterite flotation offered a new strategy for designing oxide minerals collector. That was, besides alkyl groups, some sulfhydryl minerophilic groups for sulfide minerals could be designed as preferable hydrophobic groups for oxide minerals flotation.

Comparison of the Effects of Sodium Oleate and Benzohydroxamic Acid on Fine Scheelite and Cassiterite Hydrophobic Flocculation

Sodium oleate (NaOL) and benzohydroxamic acid (BHA) are commonly used scheelite and cassiterite flotation collectors. Hydrophobic flocculation flotation of fine minerals has been extensively studied and reported under a NaOL system, but not under a BHA system. In this paper, the particle size distribution and flotation behaviour of fine scheelite (−10 μm) and cassiterite (−37 + 10 and −23 μm) after shear stirring in NaOL, BHA, and Pb2+ + BHA systems were studied by laser particle size analysis and flotation tests. The measured particle size distribution results revealed that the fine minerals could aggregate under a NaOL system, and the aggregate size increased with increasing stirring time and speed, with scheelite aggregating faster than cassiterite. BHA did not cause scheelite or cassiterite to form hydrophobic aggregates. At low stirrer speeds, the minerals could form small, weak, and easily broken aggregates when Pb2+ + BHA was added. The results of the flotation tests revealed that increasing the stirring time and speed increased the flotation rate and recovery when NaOL and BHA were added. When Pb2+ + BHA was added, however, the changes in flotation rate and recovery were not noticeable when the stirring conditions were changed.

A novel approach to improve cassiterite recovery based on grinding

In this study, a novel method of promoting cassiterite flotation involves adding Pb-BHA (Pb(NO3)2-benzohydroxamic acid) complexes to the cassiterite grinding process was investigated. The flotation result showed that adding Pb-BHA complexes before grinding had a marked effect on the cassiterite flotation recovery. The cassiterite flotation recovery with Pb-BHA complexes added before grinding was higher 42.80% than that of Pb-BHA complexes added after grinding. Moreover, it revealed a similar trend for artificial mixed minerals of cassiterite and quartz, in which the Sn recovery and grade of concentrate increased by 34.71% and 1.11%, respectively. The Fourier-transform infrared spectroscopy (FT-IR) analysis revealed that adding Pb-BHA complexes before grinding enhanced the adsorption of Pb-BHA complexes on the cassiterite surface. And the X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the chemical environment of N in Pb-BHA complexes was changed in the grinding, making it more easily to adsorb on cassiterite surface.

Optimization of conventional hydroxamic acid for cassiterite flotation: Application of structural modification under principle of isomerism

In this paper, through the structural modification of N-phenyl formohydroxamic acid (NPFHA), an isomer of benzohydroxamic acid (BHA), we designed and synthesized a series of N-phenyl hydroxamic acids (NPHA), including N-phenyl acetohydroxamic (NPHA-2), N-phenyl butyrohydroxamic acid (NPHA-4), N-phenyl hexanohydroxamic acid (NPHA-6) and N-phenyl octanohydroxamic acid (NPHA-8), and first introduced them as flotation collectors for selectively separating cassiterite from quartz and feldspar. Micro-flotation tests indicated that with increase of non-polar carbon chain length, the collecting ability to cassiterite improved dramatically. More to the point, compared to BHA, NPHA-6 and NPHA-8 possessed superior flotation performances to cassiterite and enabled the separation of cassiterite and quartz/feldspar over a wide pH range, with no application of frother or activator, providing a new insight into the development of cassiterite collector. Zeta potential experiments indicated that NPHA-8 chemisorbed onto cassiterite surfaces, with no significant adsorption to quartz or feldspar detected. DFT calculations, FT-IR and XPS analyses further demonstrated that NPHA-8 chemisorbed on cassiterite surfaces by forming C–O–Sn and N-O–Sn bonds, accompanied by proposing two interaction geometries, first with the same Sn atom of cassiterite surface, leading to a five-membered chelating ring, second with two different Sn atoms, resulting in constituting an irregular complex.

Study of the relationship between the zeta potential and floatability of cassiterite fine fractions

This article is a continuation of the authors’ research on improving the flotation process for fine tin products using zeta potential measurements on particle surfaces. The aim of the research is to establish the possibility of using certain reagents to intensify the flotation of fine cassiterite particles and to identify the mechanism behind the effect produced by the reagents on the surface of slurry particles in cassiterite flotation using zeta potential measurements. The results of experiments to select the best collector are presented, with salicylhydroxamic acid identified as the best option. Sodium hexametaphosphate pretreatment of a flotation slurry consisting of fine particles enables a more efficient cassiterite flotation, which is explained by the negative value of the z-potential for the particle surface. The use of sodium hexametaphosphate improves the yield by up to 3 %, with the mass fraction of tin growing from 1.2 to 1.75 %, and the recovery improving from 40 to 75 %. The results of z-potential measurements for the particle surface in the process of flotation indicate that its positive values are not always required and that the combined action of oxalic and sulfuric acids with salicylhydroxamic acid at a z-potential of –0.7 mV renders the maximum tin grade of 2.22 % in the froth flotation product. Gravity treatment of the flotation concentrate on concentration tables allows obtaining conditioned concentrates with the mass fractions of tin of 23.4 and 30.6 %. Finding the extremum of the z-potential for the particle surface during the flotation of tin minerals allows predicting the concentration results.