Flotation Of Kaolinite Research Articles

A novel 3-tetradecylamine propyl amidoxime collector for highly efficient flotation of fine kaolinite

How to flotation fine kaolinite efficiently is a challenge. For the improvement of fine kaolinite flotation recovery, a novel 3-tetradecylamine propyl amidoxime (TPA) collector was synthesized. In comparison to the conventional collector tetradecylamine (TDA), the fine kaolinite exhibited better floatability in the TPA system, with a recovery of 90.5% in micro-flotation experiments. It was indicated by contact angle tests that TPA was more effective in improving the hydrophobicity of kaolinite by increasing its contact angle from 24.5° to 85°. Fourier transform infrared spectroscopy (FTIR) indicated that the adsorption of TPA on kaolinite surface was by electrostatic interaction, and zeta potential tests showed a significant increase in the surface potential. In addition, it was learned that TPA interacts with the kaolinite surface more effectively than TDA by using density functional theory (DFT) calculation. Therefore, TPA with excellent performance is expected to be a novel and efficient fine kaolinite flotation collector.

Effect of Ultrasonic Pre-Treatment on the Reverse Flotation of Kaolinite From Bauxite

ABSTRACT Cationic reverse flotation of kaolinite from bauxite is an alternative to adequate high silica bauxites to the specifications of the Bayer process. However, the presence of clay minerals influences the slurries rheology decreasing the flotation performance. The objective of this work was to investigate the use of ultrasonic pre-treatment on kaolinite flotation and contrast it with the traditionally used chemical dispersant. Two bauxite samples were characterized in terms of chemical and mineralogical composition, as well as particle size distribution. Flotation was accomplished after conditioning with sodium polyacrylate and/or pre-treatment in ultrasound. Determinations of viscosity, sedimentation yield, and screening followed by the analysis of available alumina and reactive silica were also conducted. By increasing the concentration of solids to more than 20 wt.%, the slurry behavior changed from a Newtonian to a non-Newtonian behavior, the viscosity increased, and the flotation performance decreased. The use of chemical dispersant and ultrasonic pre-treatment increased the flotation performance. The ultrasound had a more marked effect in slurries with higher concentrations of solids. This result is related to the synergic effect of particle dispersion and reduction of the slime coating promoted by kaolinite onto gibbsite particles.

Substituent Effects in Kaolinite Flotation Using Dodecylamine: Experiment and DFT Study

The molecular structure of cationic surfactants is closely related to their flotation performance. In this paper, three cationic surfactants with different head group structures were selected as collectors of kaolinite, and the substituent effects were studied by the DFT method. The DFT calculation results showed that increasing the number of substituents in the dodecylamine head group can significantly increase its surface and head group charge. Dodecylamine has the lowest LUMO orbital energy, so dodecylamine has the strongest electron attraction ability and the strongest interaction with kaolinite. Electron density differential showed that there was an area of electron aggregation between the collector and the surface of the kaolinite. The interaction energy of DDA on kaolinite surfaces was greater than that of the other two collectors, indicating that the adsorption of DDA on the surface of kaolinite was more stable. Flotation results showed that higher a kaolinite yield was obtained in the presence of dodecyl dihydroxyethyl methyl ammonium chloride. The calculated results of the solvent-accessible surfaces, the head group charge, and the number of bonds between the collector and the kaolinite show good consistency with the actual flotation results of the three collectors, which can be used as a screening index for kaolinite flotation collectors.

Surface complexation model theory application in NaOL and CTAB collector adsorption differences of diaspore and kaolinite flotation

Although the relevant direct and revers flotation mechanism has been discussed a lot in diaspore and kaolinite separation, the quantitative analysis of surface-active sites and their reaction descriptions during flotation have not been reported yet. In this study, the hydration and collector adsorption reactions of anionic sodium oleate (NaOL) and cationic hexadecyl trimethyl ammonium bromide (CTAB) onto diaspore and kaolinite were quantized. Surface complexation model (SCM) was referred to obtain intrinsic reaction equilibrium constants. It can be found that for NaOL adsorption, the equilibrium constant of diaspore (1013.55) was obviously bigger than that of kaolinite (1011.76 and 1010.35 for ≡AlOH and ≡SiOH, respectively), corresponding to direct flotation of bauxite. While the interaction (103.90 for ≡XNR) between the permanent negatively charged site ≡X− and CTAB was much stronger than other sites. Besides, the single adsorbed amount in mixed minerals were successfully predicted at ratios of 1:2, 1:1 and 2:1. Finally, the fitted potential curves were also acceptable to zeta potential tests. These conclusions from SCM calculation can provide strong supports for collector adsorption differences and then help for separation much more efficiently and economically through saving preliminary exploration cost.

Enhanced kaolinite flotation using amine coated nanobubbles

In this study, kaolinite flotation using normal water and water containing pure nanobubbles (NBs) or amine coated NBs (CNBs) was investigated and the micro-flotation results showed that kaolinite floated the best when water containing CNBs was used. Rheology, settling and zeta potential tests, together with particle size distribution analyze were further employed to examine the effect of NBs (coated or not) on kaolinite particle association and its correlation with the flotation of kaolinite particles. While the zeta potential and particle size distribution results indicated an intensified attachment of CNBs on the surfaces of kaolinite, the rheology and settling results revealed the predominance of edge-to-edge and edge-to-face associations of kaolinite platelets in the presence of CNBs. It is proposed that owing to the formation of three-dimensional clay clusters which appears to be induced by the CNBs, the more favorable silica planes of kaolinite are exposed and the subsequent adsorption of amine on such planes of the kaolinite aggregates (flocs) significantly improves the flotation of kaolinite.

A novel GCMS method for the quantitative analysis of sodium oleate in froth flotation

Sodium oleate (NaOL), as an important collector, has been extensively applied in oxide and silicate mineral flotation. The quantitative determination has to be analyzed for investigating its adsorption mechanism on the mineral surface. In this study, a novel method of Gas Chromatography Mass Spectrometry (GCMS) was proposed to precisely and stably measure NaOL concentration in diaspore and kaolinite flotation pulp through methyl esterification pretreatment. Compared with Total Organic Carbon (TOC) analyzer and High Performance Liquid Chromatography (HPLC), this method can avoid systematical and manual operation error effectively, benefitting from the internal standard application of heptadecanoic acid. The obtained linear relevance coefficient is 0.99902 and the standard deviation of adsorption results on the diaspore and kaolinite is much smaller than that of TOC and HPLC.

Flotation performance of a novel Gemini collector for kaolinite at low temperature

How to sustainably produce bauxite by effective reverse froth flotation of kaolinite at low temperature is an urgent problem to be solved in the field of mineral processing. In this work, a novel amino-based Gemini surfactant butadiyl-1, 4-bis (dimethyl dodecylammonium bromide) (BBDB) was prepared and first utilized as a novel collector for kaolinite flotation. Its flotation performance for kaolinite was compared with that of the common monomolecular surfactant 1-dodecylamine (DDA) by micro-flotation tests. The tests results indicated that 95% kaolinite recovery was obtained using 2.0 × 10−4 mol/L BBDB at 25 ℃, which was half of the dosage when DDA obtained the maximum kaolinite recovery of 81%. At extremely low temperature (0 ℃), 3.0 × 10−4 mol/L BBDB could still collect 91% kaolinite, while DDA showed a frustrating ability. The contact angle tests indicated that BBDB could still significantly improve the hydrophobicity of the kaolinite surface (contact angle 71.7°) than DDA (contact angle only 25.8°) at 0 ℃. The Krafft point comparison tests indicated that BBDB had a much lower Krafft point (below 0 ℃) than DDA. Fourier transform infrared spectroscopy (FTIR)-spectrum analysis and zeta potential measurements showed that BBDB was physically adsorbed on the surface of kaolinite through electrostatic interaction.

XPS analysis of the surface chemistry of sulfuric acid-treated kaolinite and diaspore minerals with flotation reagents

Kaolinite is one of the main associated minerals (gangue) in the processing of diasporic bauxites. Sulfuric acid pretreatment has been shown to have an improving effect on kaolinite-diaspore flotation separation, but the mechanism underpinning this effect is not well known. This study reports the surface chemistry of acid-treated kaolinite and diaspore in the presence of flotation reagents (sodium hexametaphosphate (SHMP) as a depressant and dodecylamine hydrochloride (DAH) as a collector) using X-ray photoelectron spectroscopy (XPS) analysis and zeta potential determinations. Quantitative XPS analysis revealed that the Al/Si atomic ratio on the kaolinite surface was reduced after the acid treatment. Compared with natural kaolinite, acid-treated kaolinite showed weakened adsorption properties for SHMP. Consequently, there was an enhanced DAH adsorption on the acid-treated kaolinite. High-resolution XPS analysis showed formations of “unsaturated Al” components on the diaspore surface after the acid treatment, which were ready to interact with phosphite groups of SHMP to depress diaspore in kaolinite flotation. Zeta potential studies also confirmed extended SHMP adsorption on acid-treated diaspore in comparison with the natural mineral. These findings form a firm knowledge for interpreting the application of kaolinite and diaspore in many adsorption studies, including the efficient separation between kaolinite and diaspore.

Research on the reverse flotation of kaolinite from fine coal on basis of adsorption behavior

ABSTRACTThe strong hydrophilic properties of both sub-bituminous coal and kaolinite make it difficult to separate by direct flotation. In this paper, the removal of kaolinite from fine sub-bituminous coal was investigated by reverse flotation tests using N, N-dimethyl dodecyl amine (DRN12) as a kaolinite collector. In addition, the adsorption behavior of DRN12 on coal and kaolinite surfaces was also studied to explore its interaction mechanism The experimental results showed that the beneficiation of kaolinite from the raw coal was effective only in the acid pulp with DRN12 less than 1.5kg/t. Moreover, in acid solutions, DRN12 preferentially adsorbs on kaolinite surface by electrostatic force, and the adsorption capacity of DRN12 on kaolinite surface was much higher than on coal, which caused an increase of kaolinite hydrophobicity and floatability.

Bibliometric analysis on kaolinite flotation

Abstract The current work presents a bibliometric discussion on articles published worldwide concerning kaolinite flotation in international journals from 1992 to 2015. In total, 39 articles were selected from Elsevier's database, SciVerse ScienceDirect. This work allowed to recognize and identify which are the thematic and methodological trends that are being used, in addition to the main collectors used in kaolinite flotation. The results show that a significant amount of articles is produced by Chinese authors, especially from 2013, as China is the second highest aluminum producer in the world, and kaolinite is the reject in the reverse flotation process of diaspore. The results showed the difficulty of working with kaolinite flotation individually and confirmed that there is scientific collaboration among authors. Bibliometric analysis showed that the reagents used in kaolinite flotation tests are mostly derived from cationic nitrogenated compounds. Additionally, best recovery results from kaolinite flotation occurred in acidic media.

The Influence of Backwater Al3+ on Diaspore Bauxite Flotation

The effect of Al3+ in backwater on the flotation of diaspore bauxite was investigated by micro-flotation tests and the underlying mechanisms were investigated by inductively coupled plasma (ICP) measurement, zeta potential measurements, solution chemistry analyses, and synchrotron near edge X-ray absorption fine structure (NEXAFS) analyses. The ICP measurement results show the concentration of Al3+ in backwater was up to 1 × 10−4 mol/L. The micro-flotation results indicated that backwater Al3+ reduced the flotation recovery of diaspore and improved the flotation recovery of kaolinite at pH 9, which was the pH value used in the industrial flotation. The adsorption of Al3+ species changed the zeta potential, the Al atomic abundance, and the number of active sites on the mineral surface. In particular, the result of solution chemistry analyses and synchrotron NEXAFS analyses show that the Al3+ in backwater was adsorbed on the mineral surface in the form of Al(OH)3 (s), and the bond of –Al–O–Al–(OH)2 or –Al/Si–O–Al–(OH)2 was formed at pH 9. It changed the intensity of hydrogen bond force between minerals and collectors, and resulted in the depression of diaspore flotation and the activation of kaolinite flotation. This study can be used to guide the application of backwater in the flotation of diaspore bauxite in industry.

Recovery of kaolinite from tailings of Zonouz kaolin-washing plant by flotation-flocculation method

The traditional processing of kaolin is achieved by dispersion of the mined ore and classification by multistage hydrocyclone plants. The inefficiencies inherent to cyclones produce a middling product that is commonly disposed back into the quarry. In this research, recovery of kaolinite from tailings of Zonouz kaolin washing plant, which is located in Iran was investigated by flotation and flotation- flocculation. Flotation experiments show that the flotation of kaolinite from the tailings is better in an acidic than in an alkaline medium containing cationic collectors. Flotation under acidic condition causes problems such as equipment corrosion at industrial scale. As a result, the cationic flotation of kaolinite is enhanced by addition of polyacrylamide as a flocculant. The results showed flocculation by polyacrylamide improved flotation of kaolinite within a range of pH. With 300g/t dodecylamine, 500g/t aluminum chloride, 50g/t pine oil (frother), 15g/t polyacrylamide, at pH=7 and without de-slimming a product has 37.19% Al2O3, 54.19% SiO2 and 34.43% mass recovery was archived.

Flotation of fine kaolinite using dodecylamine chloride/fatty acids mixture as collector

In order to improve the flotation recovery of fine kaolinite, mixed dodecylamine chloride/fatty acid was used as collector in kaolinite flotation process.The performance of dodecylamine chloride/fatty acid mixture collector on kaolinite flotation was investigated using flotation test and computational method. Surface tension measurement, contact angle measurement and image analysis were also used to study the flotation behavior of dodecylamine chloride and mixture collectors. The flotation results showed that much higher kaolinite flotation recovery was obtained in the presence of dodecylamine chloride/octanoic acid mixture compared with that in the presence of dodecylamine chloride alone. Surface tension measurements indicated that the mixed dodecylamine chloride/octanoic acid collector was more efficient at decreasing the air–water interfacial tension. Molecular dynamics simulation showed that the octanoic acid molecules were interleaved among dodecylamine chloride ions and co-adsorbed at the kaolinite (001) surface. The relative concentration of water molecules near kaolinite (001) surface further decreased in the presence of dodecylamine chloride/octanoic acid compared with that in the presence of dodecylamine chloride alone, which indicated a much stronger hydrophobicity of the kaolinite (001) surface.

Kaolinite removal from bauxite by flotation

This paper presents a potential condition to separate kaolinite through flotation when it is present in bauxite ore. This research anticipates a Brazilian industry requirement, considering the tendency towards the need for aluminosilicates removal from bauxite ores, as has already occurred in China. Kaolinite is the most abundant aluminosilicate, and gibbsite is the main aluminum bearing mineral in Brazilian bauxite ores. The first step was a fundamental study involving microflotation experiments with pure samples of kaolinite and gibbsite. Ammonium quaternary salts and amines were used as the collector and corn starch as the depressant. In a fundamental study, the best conditions determined in the first step were evaluated for the flotation of kaolinite from bauxite ore using laboratory scale experiments. Tests with AQ142/starch (pH 10) and CTAB (pH 7) led to satisfactory results. In general, the highest values of alumina/silica mass ratio were obtained with AQ142/starch and the highest values of mass recovery and metallurgical recovery were achieved with CTAB.

Concentration of manganese tailings via reverse flotation in an acid médium

Beneficiation of manganese ores has been conducted around the world by circuits composed basically of crushing, screening and spiral classifier. Therefore, solely the coarse size fractions (and commonly the richest) are actually recovered: "lump" (-75+9mm) and "sinter feed" (-9+0.15mm). In the industrial plant which processes the ore from the Azul Mine-PA, the overflow of the spiral classifier (- 0.15mm) is disposed of in a tailings dam because it bears a low Mn content (<10%) and high kaolinite content (70%). This paper reports the findings of a process development conducted on laboratory scale with the aim of concentrating Mn-bearing minerals from the tailings of the Azul Mine-PA (7% of Mn and 70% of kaolinite). The process is composed of desliming (-10µm), followed by reverse cationic flotation of kaolinite (rougher, scavenger) at pH~5. Results indicate that the reverse cationic flotation in the acid medium, when utilizing amide amine as collector and in the presence of a silicate activator and a dispersing agent could be a possible route for the concentration of tailings that had previously been deslimed at 10µm. The results yielded a mass recovery of 18%, a metallurgical recovery of 50% and a 32% Mn concentrate which may be mixed with current high grade products, increasing the overall recovery of the plant.

Flotation of kaolinite from tailings of kaolin-washing plants by cationic collectors

Traditional processing of kaolin is achieved by dispersion of the mined ore and classification by means of multistage hydrocyclones. The inefficiencies inherent to cyclones produce a middling product that is commonly disposed back to the quarry. In this research recovery of kaolinite from tailings of the Zonoupz kaolin washing plant, which is located in Iran, was investigated by cationic flotation. Flotation experiments showed that flotation of kaolinite from tailings was much better in an acidic than in an alkaline medium containing cationic collectors.

Simulation of cluster formation from kaolinite suspensions

The behavior of kaolinite suspensions has been studied by Brownian dynamics simulation, considering the action of DLVO forces, and the results are reported in this paper. A coarse grained model for kaolinite particles was built to facilitate the computation. Cluster formation from kaolinite suspensions was found at low pH (pH5); in contrast, kaolinite particles were well dispersed at high pH (pH8). This distinguishing feature is mainly due to the anisotropic surface properties of kaolinite particles and their pH dependence. At pH5, the particles are aggregated by attraction between the negative silica face surface and the positive alumina face surface, as well as by the interaction between the negative edge surface and the positive alumina face surface. However, at pH8, all the surfaces are negatively charged, resulting in a well dispersed kaolinite suspension. The simulated results were successfully validated by SEM imaging with WETSEM capsules. Cluster formation at low pH is believed to explain success in the reverse flotation of kaolinite from bauxite ore at pH4–5 with a primary amine collector.

Significance of particle aggregation in the reverse flotation of kaolinite from bauxite ore

Significant interest has been demonstrated for the removal of kaolinite from bauxite ore by flotation. The reverse flotation of kaolinite from bauxite ore at low pH with dodecylamine hydrochloride collector has been reported. However, resolving the mechanism of the reverse flotation process is largely limited by the misunderstanding of the anisotropic surface properties of kaolinite particles. Based on recent fundamental study of the surface properties of kaolinite particles and their interaction, the significance of particle aggregation in the reverse flotation of kaolinite from bauxite ore has been revealed. The wetting characteristics of the basal plane surfaces of kaolinite with dodecylamine hydrochloride collector have been estimated by contact angle measurements at model surfaces. The improved hydrophobicity of the kaolinite nano-particles is not enough to account for the significant increase in the flotation recovery at low pH when compared to the flotation performance at high pH. Instead, particle aggregation is expected to be the major factor which contributes to the improved flotation response at low pH. Both simulation results and X-ray CT results have demonstrated aggregation and formation of kaolinite clusters at low pH. It appears that these kaolinite clusters have sufficient mass and hydrophobicity to account for the successful reverse flotation of kaolinite from bauxite ore at low pH.

A comparison study of the flotation and adsorption behaviors of diaspore and kaolinite with quaternary ammonium collectors

The flotation and adsorption behaviors of two quaternary ammonium collectors DTAC (dodecyl trimethyl ammonium chloride) and CTAC (cetyltrimethyl ammonium chloride) on diaspore and kaolinite were investigated in this work. The flotation recovery of diaspore increases with the increase of pH and the decrease of particle size, however, the situations for kaolinite are opposite. Furthermore, the influence of pH on flotation of kaolinite decreases with the decrease of particle size, and for the fine particles (undersize 0.045mm), the flotation recovery with CTAC which has a longer hydrocarbon chain and is believed to have a stronger collecting ability is lower than that with DTAC. The dramatic differences of the flotation behaviors between diaspore and kaolinite are correlated to the differences of their crystal structures. The morphologies of diaspore and kaolinite particles in different size were studied by SEM. The kaolinite particles have much larger specific surface areas (about 7 times) than the diaspore particles due to their layered structure. This leads to the differences of collector adsorption behaviors on kaolinite and diaspore and results in the different flotation behavior.

Role of Water Structure-Making/Breaking Ions in the Cationic Flotation of Kaolinite: Implications for Iron Ore Processing

Australia is the largest exporter of iron ore in the world. The high Al content in Australian hematite/goethite ores is detrimental to blast furnace and sinter plant operations. Of the Al containing minerals in iron ore, kaolinite is a common gangue mineral frequently found in iron ore deposits. In iron ore flotation pulp, various ions exist and may inter- fere with the flotation performance when their concentration is high enough. In this work, the role of a water struc- ture-making ion, i.e. Na + , and a water structure-breaking ion, i.e. K + , in the flotation of kaolinite under reverse cationic flo- tation conditions, the most widely used flotation route of iron ore in the world, was studied in a series of laboratory batch flotation tests. It was found that K + , a water structure breaker, can better reduce the zeta potential of kaolinite and thus causes higher flotation recovery of the clay mineral, in comparison to Na + , a water structure maker. The different effects of the alkali metal cations on kaolinite flotation are attributed to the different aggregation degree of kaolinite particles in the presence of these cations.