Carrier-microencapsulation for preventing pyrite oxidation

Satur, Jacqueline; Hiroyoshi, Naoki; Tsunekawa, Masami; Ito, Mayumi; Okamoto, Hideyuki

doi:10.1016/j.minpro.2007.06.003

Cited by 42 publications

(27 citation statements)

References 17 publications

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“…Current density is the anodic current of the working electrode in the working area of 1.10 cm 2 . From these results, the anodic currents of Si-Cat treated pyrite samples (1,6, and 12 h) are lower than that of the untreated pyrite. Because the anodic current represents the oxidation rate, the lower anodic currents of Si-Cat treated pyrite samples mean that the oxidation rates of these samples are lower than that of the untreated pyrite.…”

Section: Resultsmentioning

confidence: 82%

“…), stirred with a magnetic stirrer at 100 rpm. After a predetermined stirring time (1,6, and 12 h), the working electrode was air dried for 30 min, and used for electrochemical measurements in 0.10 mol/L sulfuric acid.…”

Section: Electrochemical Analysismentioning

confidence: 99%

“…After predetermined stirring time (1,6, and 12 h) at 100 rpm and 25°C, the solid residues from each treatment bottle were recovered by filtration and dried by freeze dehydration. Dry solid residue referred as Si-Cat treated pyrite samples.…”

Section: Pretreatment Of Pyrite and Morphological Analysismentioning

confidence: 99%

“…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%

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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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Section: Resultsmentioning

confidence: 82%

Section: Electrochemical Analysismentioning

confidence: 99%

Section: Pretreatment Of Pyrite and Morphological Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…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%

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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Current Approaches for Mitigating Acid Mine Drainage

Sahoo

Kim

Equeenuddin

et al. 2013

Reviews of Environmental Contamination and Toxicology

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AMD is one of the critical environmental problems that causes acidification and metal contamination of surface and ground water bodies when mine materials and/or over burden-containing metal sulfides are exposed to oxidizing conditions. The best option to limit AMD is early avoidance of sulfide oxidation. Several techniques are available to achieve this. In this paper, we review all of the major methods now used to limit sulfide oxidation. These fall into five categories: (1) physical barriers,(2) bacterial inhibition, (3) chemical passivation, ( 4) electrochemical, and (5) desulfurization.We describe the processes underlying each method by category and then address aspects relating to effectiveness, cost, and environmental impact. This paper may help researchers and environmental engineers to select suitable methods for addressing site-specific AMD problems.Irrespective of the mechanism by which each method works, all share one common feature, i.e., they delay or prevent oxidation. In addition, all have limitations.Physical barriers such as wet or dry cover have retarded sulfide oxidation in several studies; however, both wet and dry barriers exhibit only short-term effectiveness.Wet cover is suitable at specific sites where complete inundation is established, but this approach requires high maintenance costs. When employing dry cover, plastic liners are expensive and rarely used for large volumes of waste. Bactericides can suppress oxidation, but are only effective on fresh tailings and short-lived, and do not serve as a permanent solution to AMD. In addition, application of bactericides may be toxic to aquatic organisms.Encapsulation or passivation of sulfide surfaces (applying organic and/or inorganic coatings) is simple and effective in preventing AMD. Among inorganic coatings,silica is the most promising, stable, acid-resistant and long lasting, as compared to phosphate and other inorganic coatings. Permanganate passivation is also promising because it creates an inert coating on the sulfide surface, but the mechanism by which this method works is still unclear, especially the role of pH. Coatings of Fe-oxyhydroxide, which can be obtained from locally available fly ash are receiving attention because of its low cost, self-healing character, and high cementation capacity. Among organic coatings, lipids and natural compounds such as humic acid appear to be encouraging because they are effective, and have a low environmental impact and cost. Common advantages of organic vs. inorganic coatings are that they work best at low pH and can prevent both chemical and biological oxidation.However, organic coatings are more expensive than inorganic coatings. Furthermore,while organic coatings are effective under laboratory conditions, they often fail under field conditions or require large amounts of reagents to insure effectiveness.Electrochemical cover technology may become a suitable technique to prevent AMD, but the mechanism by which this technique operates is still under investigation.Limitations of this method in...

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Carrier-microencapsulation for preventing pyrite oxidation

Cited by 42 publications

References 17 publications

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

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

Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Current Approaches for Mitigating Acid Mine Drainage

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Carrier-microencapsulation for preventing pyrite oxidation

Cited by 42 publications

References 17 publications

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

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

Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Current Approaches for Mitigating Acid Mine Drainage

Contact Info

Product

Resources

About

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

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