Cassiterite Particles Research Articles

Utilization of Lead Nitrate to Enhance the Impact of Hydroxamic Acids on the Hydrophobic Aggregation and Flotation Behavior of Cassiterite.

Lead nitrate (LN) is frequently employed as an activator in the flotation of cassiterite using hydroxamic acids as the collectors. This study investigated the effect of LN on the hydrophobic aggregation of cassiterite when benzohydroxamic acid (BHA), hexyl hydroxamate (HHA), and octyl hydroxamate (OHA) were used as the collectors through micro-flotation, focused beam reflectance measurement (FBRM) and a particle video microscope (PVM), zeta potential, and the extended DLVO theory. Micro-flotation tests confirmed that LN activated the flotation of cassiterite using the hydroxamic acids as collectors. Focused beam reflectance measurement (FBRM) and a particle video microscope (PVM) were used to capture in situ data on the changes in size distribution and morphology of cassiterite aggregates during stirring. The FBRM and PVM image results indicated that the addition of LN could promote the formation of hydrophobic aggregates of fine cassiterite, when BHA or HHA was used as the collector, and reduce the dosage of OHA needed to induce the formation of hydrophobic aggregates of cassiterite. The extended DLVO theory interaction energies indicated that the presence of LN could decrease the electrostatic interaction energies (Vedl) and increase the hydrophobic interaction energies (Vhy) between cassiterite particles, resulting in the disappearance of the high energy barriers that existed between the particles in the absence of LN. Thus, cassiterite particles could aggregate in the presence of LN when BHA, HHA, or a low concentration of OHA was used as the collector.

Enhancing flotation separation of fine-grained cassiterite and calcite with cetylpyridine bromide as a dispersant

Calcite is a common gangue mineral in tin ore, which seriously affects the flotation of fine-grained cassiterite. The enhanced flotation separation of fine-grained cassiterite and calcite with cetylpyridine bromide (CPB) as a dispersant were investigated in the study. The CPB significantly improved the flotation separation efficiency of fine-grained cassiterite and calcite, and it exhibited an excellent dispersion effect and relieved the coating phenomenon of calcite particles on the surface of cassiterite particles. The CPB changed the surface potential of cassiterite from negative value to positive value when the pH was in the range of 3.4–11.5. However, regardless of treatment with CPB, the surface potential of calcite was positive when the pH was below 11.5. The O on the surface of cassiterite reacted with CPB, promoting the chemical adsorption of CPB on the surface of cassiterite. There was weak physical adsorption between CPB and calcite. The covering between cassiterite and calcite without CPB was mainly dependent on van der Waals interaction energy and electrostatic interaction energy. When CPB was in the presence, cassiterite and calcite were repelled by the hydrophobic interaction energy and electrostatic interaction energy.

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.

Hydrophobic agglomeration flotation of fine cassiterite induced by kerosene and sodium oleate

In this study, the effect of kerosene and sodium oleate (NaOL) on inducing hydrophobic agglomeration flotation of fine cassiterite was investigated through the micro-flotation tests, particle size distribution and morphological analysis, zeta potential and contact angle measurements. The results indicated that adding kerosene before NaOL could obtain a higher recovery than adding NaOL before kerosene. The agglomerates induced by adding kerosene before NaOL was dense and regular in structure with larger particle size distribution and stronger surface hydrophobicity, which jointly contributed to its higher flotation recovery. Furtherly, the extended DLVO theory calculation was carried out to explain the agglomeration behaviour of fine cassiterite under different reagents. The results convinced that under the reaction of NaOL before kerosene or kerosene before NaOL, hydrophobic interaction and sufficient kinetic energy input were necessary to form agglomerates, and the attraction effect between cassiterite particles under the reaction of kerosene before NaOL was the strongest.

Hydrophobic Flocculation of Fine Cassiterite Using Alkyl Hydroxamic Acids with Different Carbon Chain Lengths as Collectors.

This work investigated the hydrophobic flocculation of cassiterite using four alkyl hydroxamic acids with varying carbon chain lengths, i.e., hexyl hydroxamate (C6), octyl hydroxamate (C8), decyl hydroxamate (C10) and dodecyl hydroxamate (C12), as collectors. Microflotation tests were performed to investigate the flotation behaviour of cassiterite in the presence of the four alkyl hydroxamic acids. Focused beam reflectance measurement (FBRM) and a particle video microscope (PVM) were used to analyse and monitor the real-time evolution of the particle size distribution of cassiterite and the images of flocs during flocculation. The extended DLVO theory interaction energies between the cassiterite particles were calculated on the basis of the measured contact angle and the zeta potential of cassiterite to determine the aggregation and dispersion behaviour of the cassiterite particles. The microflotation test results suggested that the floatability of cassiterite improved with the increase in the carbon chain length of hydroxamates. FBRM, PVM images and extended DLVO theory calculation results indicated that when C6 was used as the collector, the cassiterite particles could not form hydrophobic flocs because the total potential energy between them was repulsive. When C8, C10 and C12 were used as collectors, the energy barrier amongst particles decreased with increasing hydroxamate concentration. The lowest concentrations of C8, C10 and C12 that could cause the hydrophobic aggregation of cassiterite were approximately 1 × 10-3, 1 × 10-4 and 2 × 10-5 mol/L, respectively. The aggregation growth rate and apparent floc size increased with an increasing collector concentration. Hydroxamic acid with a longer carbon chain could induce the cassiterite particles to form larger flocs at a lower concentration in a shorter time.

Selective flotation separation of cassiterite and calcite through using cinnamohydroxamic acid as the collector and Pb2+ as the activator

This study employs cinnamohydroxamic acid (CHA) as the collector in the flotation separation of cassiterite/calcite. Pb2+ ion is used as the activator to improve the collecting ability of CHA. This reagent system consisting of CHA collector and Pb2+ activator can achieve a higher recovery of cassiterite of ∼90% than that of calcite of ∼30%. A greater increase of 27.74% in C atomic concentration on the Pb2+-treated cassiterite surface than that of 15.21% on the Pb2+-treated calcite surface after the treatment with CHA indicates a higher adsorption amount of CHA on the Pb2+-treated cassiterite surface than that on the Pb2+-treated calcite surface, which results in its stronger ability to collect the Pb2+-activated cassiterite particles compared to the Pb2+-activated calcite particles. The treatment with CHA results in a smaller shift of ∼20 mV in the zeta potential of the Pb2+-treated cassiterite particles than that of ∼45 mV in the zeta potential of the Pb2+-treated calcite particles, which is in contradiction with the results of the X-ray photoelectron spectroscopic tests. A novel activation mechanism of Pb2+ ion for CHA flotation of cassiterite is proposed to account for this paradoxical observation. The formation of the Pb-CHA complexes is this activation mechanism of Pb2+ ion.

Adhesion between nanobubbles and fine cassiterite particles

Adhesion is an important process of particle-bubble interaction in fine particle (−10 μm) flotation. This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a high-speed camera, atomic force microscope (AFM), adsorption capacity tests, and induction time tests. After being pretreated with nanobubbles (NBs) water, fine cassiterite particles flotation tests were carried out using caprylhydroxamic acid (CHA) as a collector. The results showed that NBs can improve the recovery and flotation rate of fine cassiterite while decreasing the collector dosage. The adsorption capacity test indicated that the cassiterite treated with NBs had lower demand for collector concentration. The AFM imaging results further demonstrate that NBs could reduce the adsorption of CHA on the surface of minerals. Since NBs played a part of the role of collector, it can improve the flotation effect while reducing the amount of collector. The induction time test and the high-speed camera observation test showed that NBs promoted the attachment between bubbles and cassiterite particles. On the other hand, NBs agglomerate cassiterite particles, increasing the probability of particles colliding with bubbles.

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.

A recipe of surfactant for the flotation of fine cassiterite particles

Salicylhydroxamic acid (SHA) has been widely used as collector in cassiterite flotation, and α-terpineol (AT) and methyl isobutyl carbinol (MIBC) are common frothers in mineral flotation. The effects of AT and MIBC on cassiterite flotation have rarely been reported, which severely limits our understandings of the role of frother in cassiterite flotation. Here, comparative studies between AT and MIBC in affecting cassiterite flotation using SHA as collector were conducted through micro-flotation tests. Micro-flotation tests showed that the averaged value of the recovery of cassiterite with AT was 10% higher than that with MIBC at the same concentration. To unveil the mechanisms of enhancement effects of AT on the flotation of fine cassiterite particles, zeta potential measurements, contact angle measurements and surface tension measurements were conducted. Zeta potential of cassiterite surface shifted to more negative value in the presence of SHA, and the nonionic reagents, AT and MIBC, could not affect the surface potential of cassiterite. Contact angle measurements showed AT could adsorb on the surfaces of cassiterite particles, and therefore the hydrophobicity of particles was increased. In addition, there was a synergistic behavior between SHA and AT on cassiterite surface due to co-adsorption, and the cassiterite surface was more hydrophobic in the SHA/AT solution. Less surface tension and smaller bubble size were obtained in the SHA/AT solution compared to SHA/MIBC solution. These two combining effects, i.e. increasing the hydrophobicity of cassiterite particles and reducing the single bubble size, are beneficial to the flotation of cassiterite, which explains higher recoveries in cassiterite flotation when AT is used as frother and SHA as collector.

A selective flotation of cassiterite with a dithiocarbamate-hydroxamate molecule and its adsorption mechanism

N-[(3-hydroxyamino)-propoxy]-N-octyl dithiocarbamate (OAHD) was designed as cassiterite flotation collector. AFM clearly showed that OAHD assembled on cassiterite surfaces to generate innumerable nano-aggregates. The FTIR and XPS recommended that the adsorption of OAHD was related to forming the ▪ and ▪ configurations in the surface OAHD-Sn(IV) complexes, which improved the hydrophobicity, decreased the surface energy and hydrophilicity index, and realized an effective flotation enrichment of cassiterite particles. In addition, the dithiocarbamate group might act as a hydrophilic group for calcite flotation, while as a chelating group for cassiterite flotation, which rendered OAHD to return the lower flotation recovery of calcite than octyl hydroxamic acid, and the excellent collecting properties towards cassiterite.

Effects of bubble size, velocity, and particle agglomeration on the electro‐flotation kinetics of fine cassiterite

AbstractHydrodynamic behavior of fine particles and bubbles and their influences on the particle–bubble collision efficiency (Ec) in an electro‐flotation system were analyzed in this study. The influence of sodium oleate on the agglomeration of cassiterite particles and the effect of electrolyte (Na2SO4) concentration on the zeta potential of cassiterite were investigated in detail, respectively. Bubble trajectory was recorded by using a high‐speed camera to investigate the dynamic process in terms of bubble velocity. Moreover, bubble size was taken into account in the determination of the relationship between bubble velocity and Ec. The Reynolds number (Reb) was calculated to be 4.77 for hydrogen (H2) bubbles with a mean diameter of 52 μm. The highest recovery of cassiterite particles (<10 μm) was obtained by using 20 μm bubbles during flotation. The results indicate that the Yoon–Luttrell intermediate fluid (between the Stokes and potential flows) condition is applicable for the cassiterite electro‐flotation system, and Ec is improved by controlling the size and velocity of the hydrogen bubble, and the agglomeration of fine cassiterite particles in electro‐flotation. Additionally, it was greatly inspired to explore bubble–particle attachment in dissolved air flotation from these results.

In Situ Investigation of the Adsorption of Styrene Phosphonic Acid on Cassiterite (110) Surface by Molecular Modeling

Abstract: The flotation, adsorption and bonding mechanisms of styrene phosphonic acid (SPA) to cassiterite were studied using microflotation tests, zeta potential measurements, solution chemistry analysis and density functional theory (DFT) calculations in this paper. Flotation results demonstrated SPA was an excellent collector for cassiterite which could recover over 85% cassiterite particles with the pH range 4.3–6.06 and 40 mg/L SPA. Zeta potential measurements and solution chemistry analysis revealed the adsorption of SPA was mainly contributed by the chemisorption of the monoanions on cassiterite surfaces. Frontier molecular orbital theory analysis and adsorption energy calculation results proved the monoanion of SPA was able to replace the OH− on cassiterite surfaces. The adsorption structure optimization results confirmed the binuclear complex was the most favorable adsorption configuration of SPA on cassiterite (110) surface. Mulliken population calculations and density of states analysis indicated during the bonding process the Sn3 atom lost electrons to O3 atom, and the bonding interaction between O3 and Sn3 atoms was mainly from the contribution of the 2p orbital of O3 atom and the 5s and 5p orbitals of Sn3 atom.

The Recovery of Fine Cassiterite from Metasedimentary Rock

It is known that ore containing cassiterite (SnO2) has been our most important source of tin since antiquity and its successful separation continuously pose problems to mineral processors. The situation is more pronounced since the depletion of the more easily recoverable alluvial reserves forces us to work with the more complex deposits such as hardrock cassiterite ores. In order to understand more about the challenges in processing complex tin ore deposits, a metasedimentary rock ore sample from a mine in Malaysia was used in this study. Chemical analysis by wet method shows that SnO2 content in the sample was 2.86%, while for mineralogical analysis, the x-ray diffractogram (XRD) of the sample had identified that besides cassiterite, the sample also contained minerals such as quartz (SiO2) and clinochlore. Furthermore, the FESEM (field emission scanning electron microscope) micrograph analysis carried out on a polish section of the sample indicated that the fine cassiterite particles (approximately 80 µm) were found to be disseminated in the quartz minerals. Prior to the separation processes, grindability studies were carried-out on crushed samples to liberate the cassiterite from other gangue minerals and at the same time, avoid producing high percentage of fines. For the separation of tin from gangue minerals on the ground samples, two stages of gravity separations by shaking tables were carried out. The first stage was run on ground samples and for the second stage, the middling product from the first stage was re-tabled. Magnetic separation process on Concentrate 1 (stage 1) and Concentrate 2 (stage 2) products from the shaking table increased the grade of SnO2 to 46.85% and 61.90% respectively (as a non-magnetic products). Further concentration process of these non-magnetic products by high tension separator, increased the grade of SnO2 from 85.05% to 98.77%.

Collision and attachment behavior between fine cassiterite particles and H2 bubbles

Particle–bubble interaction during electro-flotation of cassiterite was investigated by determining the recovery of cassiterite and the collision mechanism of cassiterite particle and H2 bubble. Flotation tests at different conditions were conducted in a single bubble flotation cell. The recovery of cassiterite was found to be affected by cassiterite particle and bubble size. A matching range, in which the best recovery can be obtained, was found between particle and bubble size. Collision, attachment, and detachment of the particle–bubble were observed and captured by a high-speed camera. Particle–bubble collision and attachment were analyzed with the use of particle–bubble interaction theory to obtain the experimental results. An attachment model was introduced and verified through the photos captured by the high-speed camera. A bridge role was observed between the bubbles and particles. Particle–bubble interaction was found to be affected by bubble size and particle size, which significantly influenced not only the collision and attachment behavior of the particles and bubbles but also the flotation recovery of fine cassiterite particles.

Electroflotation of cassiterite fines using a hydrophobic bacterium strain

In this work, the electroflotation of cassiterite fine ranges using Rhodococcus opacus (R. opacus) as bioreagent has been carried out. The interaction between R. opacus and mineral surface was valued through the zeta potential, contact angles measurements and adsorption studies. Furthermore, studies were attempted to check the effect of current density and microorganism concentration on mean bubble size (Sauter). After the interaction, the resulting particles exhibited hydrophobic characters, as verified by the increase of the contact angle. Also, the electrophoretic mobilities of cassiterite particles showed a mean value close to zero after interaction with R. opacus. The measurement of bubble size by laser diffraction showed a mean bubble size of 26µm. Current density and bacterial concentration seem to be the main parameters affecting the mean diameter of the bubbles. An electroflotation test reported recovery of around 64.5% at pH 5, concentration of 2.87x10¹² cells/ml (50 mg/L) and current density of 51.4 mA/cm².

Size and shape fine-tuning of SnO2 nanoparticles for highly efficient and stable dye-sensitized solar cells

Innovative solution routes led to two types of tin dioxide nanocrystals, i.e. 10–15 nm spheroid cassiterite nanoparticles and 50–150 nm anisotropic cassiterite particles showing octahedral facets. Nanoporous SnO2 electrodes of various architectures (mono- or bilayered) were then processed by the screen-printing method using suitable combinations of these SnO2 particles; the final texture, composition and morphology of the photoanodes obtained depending upon the nature of the post-treatment (with or without TiCl4). After sensitization by the ruthenium dye N719, ATR-FTIR studies revealed that chemisorption of the dye onto porous cassiterite SnO2 layers took place through a bridging coordination mode. As-prepared dye-sensitized photoanodes, when embedded in DSC devices containing a liquid electrolyte, led to a record overall power conversion efficiency (PCE) of 3.2% for pure SnO2 composed of both kinds of particles and to very promising PCE above 4% for photoanodes post-treated with TiCl4. The remarkable photovoltaic performances of the photoanodes including both kinds of particles, associated or not with a TiCl4 post-treatment, were due to improved Voc and FF, and were related to: (i) lower charge transfer resistance at the SnO2–N719–electrolyte interface; (ii) onset of dark current occurring at higher potential; (iii) enhanced electron lifetimes as determined by transient Voc decay measurements. Finally, the most striking feature of this study concerns the improvement of the power conversion efficiency upon aging under ambient conditions and the amazing long-term stability of DSCs fabricated from different SnO2-based photoanodes since standard devices built from N719 dye and I3−/I− electrolytes usually show fast decrease of efficiency.

Electro-flotation and collision-attachment mechanism of fine cassiterite

In order to discuss the particle-bubble interaction during the electro-flotation of cassiterite, the recovery of cassiterite with different particle sizes was investigated, and the collision mechanism between the cassiterite particles and H2 bubbles was explored. The flotation tests were carried out in a single bubble flotation cell. The results show that cassiterite particles <10 μm, 10–20 μm, 20–38 μm and 38–74 μm match with bubbles with size of 50–150 μm, about 250 μm, 74 μm and 74 μm, respectively, and a better recovery can be obtained. It is demonstrated that the recovery of cassiterite is influenced by the size of cassiterite particles and bubbles. Furthermore, the probabilities of collision, adhesion, detachment and collection were calculated using the collision, attachment and collection models. Theoretical calculation results show that the collision probability decreases sharply with decreasing particle size and increasing bubble size (below 150 μm). The attachment probability would increase from the effective collision, leading to the increase of recovery.

The Application of119Sn Mössbauer Spectroscopy to the Investigation of Glass Coatings: Evolution of the Tin Species in Lead-Rich White Glazes

119Sn Mossbauer spectroscopy and X-ray diffraction were used to study the state of tin in opaque lead rich glazes, where small cassiterite (SnO2) particles serve as opacifiers.

New Fluorinated Stannic Compounds as Precursors of F-Doped SnO(2) Materials Prepared by the Sol-Gel Route.

Dialkoxydi(beta-diketonate)tin(IV) compounds react either with difluorodi(beta-diketonate)tin(IV) or with butanoyl fluoride to yield novel tin complexes Sn(OR(1))F(R(2)COCHCOR(2))(2) 1 (R(1) = tert-amyl, isopropyl, ethyl; R(2) = methyl, tert-butyl). Multinuclear (1)H, (13)C, (19)F, and (119)Sn NMR spectroscopic characterization showed that complexes 1 are octahedral in solution with a cis configuration for the fluorine and the alkoxide group. Kinetics of configurational rearrangements were studied by variable-temperature (13)C NMR spectroscopy. The hydrolytic behavior of 1 was determined for different hydrolysis ratios h = [H(2)O]/[1]. For R(1) = tert-amyl, a dimeric fluorinated species was mainly obtained for h = 0.5, and addition of 2 mol equiv of water led to a fluorinated stannic oxopolymer soluble in CH(3)CN. In the latter case, the powder obtained after solvent elimination and treatment in air at 550 degrees C consisted of crystalline SnO(2) cassiterite particles containing the required amount (3 mol %) of doping fluorine and exhibiting electronic conductivity comparable to that of Sn-doped In(2)O(3). Complexes 1 are the first precursors of F-doped SnO(2) materials prepared by the sol-gel route.

Single particle analysis of suspended matter in the Makasar Strait and Flores Sea with particular reference to tin-bearing particles

Suspended matter samples filtered from surface waters and two depth profiles from the Flores Sea and Makasar Strait were investigated by electron probe X-ray microanalysis (EPXMA) and laser microprobe mass analysis (LAMMA). EPXMA yielded discrete morphological and chemical analysis of the major particle types of suspended matter. Cluster analysis revealed that thirteen main particle types described the composition of suspended matter of the Flores Sea and Makasar Strait. Silicates, aluminosilicates and Fe-oxyhydroxides were the predominant particle types. Suspended matter of the basins studied contained high levels of tin-bearing particles. On the basis of their composition, tin particles can be divided into three groups: (1) tin oxide/hydroxides (cassiterite, romarchite, hydroromarchite); (2) iron-oxyhydroxides with adsorbed tin; and (3) mixed oxidation state tin hydroxysulphates. Only ultra-fine cassiterite particles enter the seawater in suspended state. Dissolved tin species entering the sea have three alternatives: (1) to be scavenged by Fe-oxyhydroxides; (2) to precipitate as tin oxide/hydroxides (romarchite, hydroromarchite); (3) to precipitate as tin hydroxysulphates. The conclusion is that dissolved and suspended tin originate from local sources in the land frame of the basins as well as from remote sources in the Indonesian Archipelago. Four different sectors of the waters studied have suspended matter with different composition: (1) the Mahakam River–Delta zone; (2) the open Flores Sea; (3) the landlocked Saleh Bay; (4) the Makasar Strait proper. The depth distribution of suspended particle types is mainly influenced by: (1) the bottom nepheloid layer and calcite lysocline in the Flores Sea; (2) the high bioproduction in the surface water layer and the vertical distribution of organic matter in the Makasar Strait.