Carrier-microencapsulation using Si–catechol complex for suppressing pyrite floatability

Jha, Rani; Satur, Jacqueline; Hiroyoshi, Naoki; Ito, Mayumi; Tsunekawa, Masami

doi:10.1016/j.mineng.2008.02.011

Cited by 23 publications

(11 citation statements)

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“…The selective layer formation is assumed to be due to the differences in the electrical conductivities of pyrite and coal: pyrite is a semiconductor but coal is an insulator. A hydrophilic SiO 2 or Si(OH) 4 coating is formed on the pyrite surface as follows [17,18]: the Si(cat) 3 2-complex adsorbs on the anodic site of the pyrite surface and decomposes into quinone and Si 4+ ion, according to:…”

Section: Resultsmentioning

confidence: 99%

“…The metal ion released from the complex hydrolyzes to form a thin layer of metal oxide or hydroxide on the pyrite surface [17,18]. In the previous papers, it was reported that the layer formed by CME treatment is hydrophilic and protective against oxidation;…”

Section: +mentioning

confidence: 99%

“…therefore CME can suppress the floatability and oxidation of pyrite [17,18]. If CME can form a hydrophilic metal oxide/hydroxide layer on pyrite but not on coal, then it can be used as a depressant for pyrite in coal-pyrite flotation.…”

Section: +mentioning

confidence: 99%

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Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Jha

Satur

Hiroyoshi

et al. 2011

Fuel Processing Technology

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Carrier microencapsulation, CME, is a technique to form a thin layer of metal oxide or hydroxide on pyrite surface using a water soluble organic carrier combined with metal ions. The present study investigated the effect of CME using tris-catecholato complex of Si 4+ , Si(cat) 3 2-on pyrite-coal separation by dynamic bubble pick-up experiments and Hallimond tube flotation experiments using coal, pyrite, and a coal-pyrite mixture. The mineral samples were treated in 0-5 mol m -3 Si(cat) 3 2-solutions at pH 4-9 at treatment times of 1-24 h. Dynamic bubble pick-up experiments showed that CME treatment 2 converted the pyrite surface from hydrophobic to hydrophilic but did not affect coal's hydrophobic surface. The results of the Hallimond tube flotation experiments of a coal-pyrite mixture at pH 7-9 in the presence of kerosene as a collector showed that pyrite floatability was selectively suppressed after 1 h CME treatment with 0.5 mol m -3 Si(cat) 3 2-while both coal and pyrite were floated without the treatment.This indicates that CME treatment is effective in suppressing pyrite floatability in coal-pyrite flotation.

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Section: Resultsmentioning

confidence: 99%

Section: +mentioning

confidence: 99%

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Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Jha

Satur

Hiroyoshi

et al. 2011

Fuel Processing Technology

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“…For example, prolonged exposure even to minute amounts of As increases the risks of developing several types of cancers [1]. To mitigate this problem, carrier-microencapsulation (CME), a process that forms a protective coating on the surface of sulfide minerals, was developed by the authors [2][3][4][5]. In CME, a redoxsensitive organic compound (e.g., catechol, 1,2dihydroxybenzene, C6H4(OH)2) is used to transform relatively insoluble metal(loid) ions, such as Ti 4+ , Si 4+ , and Al 3+ , into soluble complexes.…”

Section: Introductionmentioning

confidence: 99%

Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation

Tabelin

Inano

et al. 2019

MATEC Web Conf.

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Arsenopyrite is the most common arsenic-bearing sulfide mineral in nature. It is readily oxidized and releases toxic arsenic (As) into the environment when exposed to atmospheric conditions via anthropogenic activities like mining, mineral processing, extractive metallurgy, and underground space developments. Carrier-microencapsulation (CME) is a technique that uses metal(loid)-organic complexes to selectively form protective coatings on the surfaces of sulfide minerals. In this study, CME using Al-catecholate complexes (i.e., Al-based CME) was investigated to suppress the oxidation of arsenopyrite. Aluminum(III) and catechol form three complex species depending on the pH and among them, [Al(cat)]+ was the most effective in suppressing arsenopyrite oxidation. Its suppressive effect was improved as [Al(cat)]+ concentration increased due most likely to the formation of a more extensive surface protective coating at higher concentrations. Surface characterization of leaching residues using SEM-EDX and XPS indicates that CME-treated arsenopyrite was covered with bayerite (γ-Al(OH)3). The results of electrochemical studies showed that the surface protective coatings suppressed both anodic and cathodic half-cell reactions of arsenopyrite oxidation.

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“…Numerous passivation agents have been investigated. 4,5) A method known as carrier microencapsulation (CME) that uses aqueous solutions of metal ions (Si 4+ or Ti 4+ ) complexed with an organic carrier such as catechol (Cat), i.e., Si [Cat] 3 2¹ or Ti[Cat] 3 2¹ , proposed by Satur et al 6) and Jha et al 7,8) has become a promising method for the practical suppression of pyrite oxidation. 68) In this method, complexed Si [Cat] 3 2¹ or Ti[Cat] 3 2¹ is decomposed selectively on the surface of pyrite to form a silicon or titanium oxide and/ or hydroxide coating that protects against oxidation.…”

Section: Introductionmentioning

confidence: 99%

Silicate Covering Layer on Pyrite Surface in the Presence of Silicon–Catechol Complex for Acid Mine Drainage Prevention

et al. 2015

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In this paper, prevention of pyrite oxidation by carrier microencapsulation (CME) was investigated. A possible layer structure was suggested following analysis with electrochemical and surface analysis techniques. Electrochemical study of treated pyrite samples showed that treatment with siliconcatechol (Si-Cat) for 6 h at an initial pH of 9.5 gave the best barrier properties and suppression of the samples. Scanning electron microscopy with energy-dispersive X-ray, and Fourier transform infrared (FTIR) analyses confirmed the presence of a silicate layer on the surface of treated pyrite. X-ray photoelectron spectroscopy indicated that the coating layers on the treated pyrite samples consisted of a network of Fe-O-Si and Si-O-Si units bonded to the surface of pyrite. The Si-O-C asymmetric stretching mode was also observed in FTIR spectra. Detailed spectroscopic analyses confirmed the formation of a silicate polymer on a silicaquinone layer, which resulted in the effective suppression effect shown by Si-Cat-treated pyrite at increasing pH.

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Carrier-microencapsulation using Si–catechol complex for suppressing pyrite floatability

Cited by 23 publications

References 4 publications

Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation

Silicate Covering Layer on Pyrite Surface in the Presence of Silicon–Catechol Complex for Acid Mine Drainage Prevention

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Carrier-microencapsulation using Si–catechol complex for suppressing pyrite floatability

Cited by 23 publications

References 4 publications

Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation

Silicate Covering Layer on Pyrite Surface in the Presence of Silicon&ndash;Catechol Complex for Acid Mine Drainage Prevention

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Silicate Covering Layer on Pyrite Surface in the Presence of Silicon–Catechol Complex for Acid Mine Drainage Prevention