Advances in Selective Flotation and Leaching Process in Metallurgy

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Extractive Metallurgy".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 34933

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Guest Editor
Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-0808, Japan
Interests: mineral processing; flotation; hydrometallurgy; leaching; electrochemistry; resource recycling; environmental remediation; acid mine drainage; sulfide passivation
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Dear Colleagues,

Metals are a finite resource, which is necessary to maintain living standards in modern society due to their countless applications like transportation vehicles, building and construction, household appliances, electronic devices, etc. In addition, the world is rapidly transitioning to “low-carbon technologies” using renewable energy sources (e.g., solar, wind, etc.) to combat climate change, and these technologies require vast amounts of metals per unit generation compared to that of conventional fossil generation; for example, 11–40 times more copper (Cu) for solar photovoltaic (PV) systems and 6–14 times more iron (Fe) for wind power stations.

Unfortunately, easily exploitable ore deposits are hard to find, which makes it unavoidable that mining industries must develop complicated ore deposits with low-grade and fine grain-size. The complexity of these ore bodies requires fine grinding to achieve the appropriate liberation of valuable minerals. Typically, there are two scenarios to extract metals from finely-ground ores; that is, (1) concentration of valuable minerals via “flotation” followed by smelting process and (2) direct extraction of metals from finely-ground ores by “leaching” followed by purification and recovery processes (e.g., solvent extraction and electrowinning; SX-EW). Therefore, flotation and leaching, both of which are the first stage of each scenario, of finely-ground ores are of crucial importance to assure the continued supply of metals.

This Special Issue will be devoted to collecting papers on recent advances in selective flotation and leaching processes for any metal-containing ores. It is my pleasure to invite you to contribute to this Special Issue, and your valuable contribution will make this Special Issue successful. Both original research papers and reviews are all welcome. The topics of interest include, but are not limited to, selective flotation, selective depression, fine particle flotation, bioflotation, atmospheric leaching, pressure leaching, bioleaching, mineral processing, and hydrometallurgy.

Dr. Ilhwan Park
Guest Editor

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Keywords

  • selective flotation
  • selective depression
  • fine particle flotation
  • bioflotation
  • atmospheric leaching
  • pressure leaching
  • bioleaching
  • mineral processing
  • hydrometallurgy

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Published Papers (12 papers)

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Editorial

Jump to: Research, Review

4 pages, 186 KiB  
Editorial
Advances in Selective Flotation and Leaching Process in Metallurgy
by Ilhwan Park
Metals 2022, 12(1), 144; https://0-doi-org.brum.beds.ac.uk/10.3390/met12010144 - 12 Jan 2022
Cited by 2 | Viewed by 1475
Abstract
Metals are a finite resource that are necessary to maintain living standards in modern society, due to their countless applications, such as transportation vehicles, building and construction, household appliances, electronic devices, etc. [...] Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)

Research

Jump to: Editorial, Review

12 pages, 2785 KiB  
Article
Development of Hydrometallurgical Process for Recovery of Rare Earth Metals (Nd, Pr, and Dy) from Nd-Fe-B Magnets
by Pankaj Kumar Choubey, Nityanand Singh, Rekha Panda, Rajesh Kumar Jyothi, Kyoungkeun Yoo, Ilhwan Park and Manis Kumar Jha
Metals 2021, 11(12), 1987; https://0-doi-org.brum.beds.ac.uk/10.3390/met11121987 - 09 Dec 2021
Cited by 10 | Viewed by 3036
Abstract
Non-availability of rich primary resources of rare earth metals (REMs) and the generation of huge amounts of discarded magnets containing REMs, compelled the researchers to explore the possibilities for the recovery of REMs from discarded magnets. Therefore, the present paper reports the recovery [...] Read more.
Non-availability of rich primary resources of rare earth metals (REMs) and the generation of huge amounts of discarded magnets containing REMs, compelled the researchers to explore the possibilities for the recovery of REMs from discarded magnets. Therefore, the present paper reports the recovery of REMs (Nd, Pr, and Dy) from discarded Nd-Fe-B magnets. The process consists of demagnetization, pre-treatment, and hydrometallurgical processing to recover REMs as salt. Leaching studies indicate that 95.5% Nd, 99.9% Pr, and 99.9% Dy were found to be dissolved at the optimized experimental condition i.e., acid concentration 2 M H2SO4, temperature 75 °C, pulp density 100 g/L, and mixing time 60 min. Solvent extraction technique was tried for the selective extraction/separation of REMs and Fe. The result indicates that 99.1% (24.42 g/L) of Nd along with 90% (1.08 g/L) of Pr and total Fe were co-extracted using 35% Cyanex 272 at organic to aqueous (O/A) ratio 1/1, eq. pH 3.5 in 10 min of mixing time. It requires multistage separation and therefore, not feasible in view of economics. Thus, direct precipitation of REMs salt and iron oxide as pigment was studied using two stages of precipitation at different pH. The obtained precipitate of REMs and Fe hydroxides were dried separately to remove the moisture and further treated at elevated temperature to get pure REMs oxide and red oxide. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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14 pages, 4660 KiB  
Article
The Effects of Coexisting Copper, Iron, Cobalt, Nickel, and Zinc Ions on Gold Recovery by Enhanced Cementation via Galvanic Interactions between Zero-Valent Aluminum and Activated Carbon in Ammonium Thiosulfate Systems
by Sanghee Jeon, Sharrydon Bright, Ilhwan Park, Carlito Baltazar Tabelin, Mayumi Ito and Naoki Hiroyoshi
Metals 2021, 11(9), 1352; https://0-doi-org.brum.beds.ac.uk/10.3390/met11091352 - 27 Aug 2021
Cited by 10 | Viewed by 2834
Abstract
The use of galvanic interactions between zero-valent aluminum (ZVAl) and activated carbon (AC) to recover gold (Au) ions is a promising technique to overcome the challenges due to the poor recovery in ammonium thiosulfate systems, but the applicability to practical Au ore processing [...] Read more.
The use of galvanic interactions between zero-valent aluminum (ZVAl) and activated carbon (AC) to recover gold (Au) ions is a promising technique to overcome the challenges due to the poor recovery in ammonium thiosulfate systems, but the applicability to practical Au ore processing remains elusive so far. The present study describes (1) the recovery of Au ions from low Au concentrations, which are typical concentrations used in Au ore processing; and (2) an investigation into the effects of various coexisting base metal ions that can be present in pregnant ore-leached solutions. The results showed that high Au recovery (i.e., over 85%) was obtained even at low Au concentrations under the following conditions: 1:1 of 0.15 g of ZVAl and AC with 10 mL of ammonium thiosulfate solution containing 5 mg/L of Au ions at 25 °C for 1 h in an anoxic atmosphere. Selected coexisting metal ions (i.e., copper, iron, cobalt, nickel, and zinc) were studied to establish their effects on Au recovery, and the results showed that the Au recovery was enhanced (about 90%) when copper ions coexist in the solution with minimal effects from other competing base metal ions. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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13 pages, 22674 KiB  
Article
Copper Recovery and Reduction of Environmental Loading from Mine Tailings by High-Pressure Leaching and SX-EW Process
by Labone L. Godirilwe, Kazutoshi Haga, Batnasan Altansukh, Yasushi Takasaki, Daizo Ishiyama, Vanja Trifunovic, Ljiljana Avramovic, Radojka Jonovic, Zoran Stevanovic and Atsushi Shibayama
Metals 2021, 11(9), 1335; https://0-doi-org.brum.beds.ac.uk/10.3390/met11091335 - 24 Aug 2021
Cited by 7 | Viewed by 3495
Abstract
The flotation tailings obtained from Bor Copper Mine contain pyrite (FeS2) and chalcopyrite (CuFeS2), these sulfide minerals are known to promote acid mine drainage (AMD) which poses a serious threat to the environment and human health. This study focuses [...] Read more.
The flotation tailings obtained from Bor Copper Mine contain pyrite (FeS2) and chalcopyrite (CuFeS2), these sulfide minerals are known to promote acid mine drainage (AMD) which poses a serious threat to the environment and human health. This study focuses on the treatment of mine tailings to convert the AMD supporting minerals to more stable forms, while simultaneously valorizing the mine tailings. A combination of hydrometallurgical processes of high-pressure oxidative leaching (HPOL), solvent extraction (SX), and electrowinning (EW) were utilized to recover copper from mine tailings which contain about 0.3% Cu content. The HPOL process yielded a high copper leaching rate of 94.4% when water was used as a leaching medium. The copper leaching kinetics were promoted by the generation of sulfuric acid due to pyrite oxidation. It was also confirmed that a low iron concentration (1.4 g/L) and a high copper concentration (44.8 g/L) obtained in the stripped solution resulted in an improved copper electrodeposition current efficiency during copper electrowinning. Moreover, pyrite, which is primarily in the mine tailings, was converted into hematite after HPOL. A stability evaluation of the solid residue confirmed almost no elution of metal ions, confirming the reduced environmental loading of mine tailings through re-processing. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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19 pages, 8399 KiB  
Article
Flotation Performance, Structure-Activity Relationship and Adsorption Mechanism of O-Isopropyl-N-Ethyl Thionocarbamate Collector for Elemental Sulfur in a High-Sulfur Residue
by Guiqing Liu, Bangsheng Zhang, Zhonglin Dong, Fan Zhang, Fang Wang, Tao Jiang and Bin Xu
Metals 2021, 11(5), 727; https://0-doi-org.brum.beds.ac.uk/10.3390/met11050727 - 28 Apr 2021
Cited by 3 | Viewed by 1713
Abstract
O-isopropyl-N-ethyl thionocarbamate (IPETC) collector was used to selectively recover elemental sulfur from a high-sulfur residue, and its flotation performance, structure–property relationship and adsorption mechanism to elemental sulfur were studied. The raw ore flotation test showed that IPETC displayed superior flotation performance to the [...] Read more.
O-isopropyl-N-ethyl thionocarbamate (IPETC) collector was used to selectively recover elemental sulfur from a high-sulfur residue, and its flotation performance, structure–property relationship and adsorption mechanism to elemental sulfur were studied. The raw ore flotation test showed that IPETC displayed superior flotation performance to the elemental sulfur compared with sodium ethyl xanthate (SEX) and ammonium dibutyl dithiophosphate (ADDTP) collectors. Pure mineral flotation and adsorption experiments further demonstrated that among the three collectors, IPETC had the strongest collecting power and the optimum selectivity towards elemental sulfur. The structure–property relationship research based on density functional theory (DFT) calculation supported the above conclusion. The adsorption mechanism analysis manifested that IPETC adsorption on elemental sulfur surface was a chemical process by separately generating normal covalent bond between carbonyl S atom and S atom and a backdonation covalent bond between O atom and S atom, which was confirmed by the FTIR spectrum analysis result. IPETC exhibits excellent collecting ability and selectivity for elemental sulfur and therefore it has bright application prospects. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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11 pages, 1899 KiB  
Article
Flotation Separation of Chalcopyrite and Molybdenite Assisted by Microencapsulation Using Ferrous and Phosphate Ions: Part II. Flotation
by Ilhwan Park, Seunggwan Hong, Sanghee Jeon, Mayumi Ito and Naoki Hiroyoshi
Metals 2021, 11(3), 439; https://0-doi-org.brum.beds.ac.uk/10.3390/met11030439 - 07 Mar 2021
Cited by 11 | Viewed by 2040
Abstract
Porphyry-type deposits are the major sources of copper and molybdenum, and flotation has been adopted to recover them separately. The conventional reagents used for depressing copper minerals, such as NaHS, Na2S, and Nokes reagent, have the potential to emit toxic H [...] Read more.
Porphyry-type deposits are the major sources of copper and molybdenum, and flotation has been adopted to recover them separately. The conventional reagents used for depressing copper minerals, such as NaHS, Na2S, and Nokes reagent, have the potential to emit toxic H2S gas when pulp pH was not properly controlled. Thus, in this study the applicability of microencapsulation (ME) using ferrous and phosphate ions as an alternative process to depress the floatability of chalcopyrite was investigated. During ME treatment, the use of high concentrations of ferrous and phosphate ions together with air introduction increased the amount of FePO4 coating formed on the chalcopyrite surface, which was proportional to the degree of depression of its floatability. Although ME treatment also reduced the floatability of molybdenite, ~92% Mo could be recovered by utilizing emulsified kerosene. Flotation of chalcopyrite/molybdenite mixture confirmed that the separation efficiency was greatly improved from 10.9% to 66.8% by employing ME treatment as a conditioning process for Cu-Mo flotation separation. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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14 pages, 11941 KiB  
Article
Flotation of Seafloor Massive Sulfide Ores: Combination of Surface Cleaning and Deactivation of Lead-Activated Sphalerite to Improve the Separation Efficiency of Chalcopyrite and Sphalerite
by Kosei Aikawa, Mayumi Ito, Atsuhiro Kusano, Ilhwan Park, Tatsuya Oki, Tatsuru Takahashi, Hisatoshi Furuya and Naoki Hiroyoshi
Metals 2021, 11(2), 253; https://0-doi-org.brum.beds.ac.uk/10.3390/met11020253 - 02 Feb 2021
Cited by 12 | Viewed by 2692
Abstract
The purpose of this study is to propose the flotation procedure of seafloor massive sulfide (SMS) ores to separate chalcopyrite and galena as froth and sphalerite, pyrite, and other gangue minerals as tailings, which is currently facing difficulties due to the presence of [...] Read more.
The purpose of this study is to propose the flotation procedure of seafloor massive sulfide (SMS) ores to separate chalcopyrite and galena as froth and sphalerite, pyrite, and other gangue minerals as tailings, which is currently facing difficulties due to the presence of water-soluble compounds. The obtained SMS ore sample contains CuFeS2, ZnS, FeS2, SiO2, and BaSO4 in addition to PbS and PbSO4 as Pb minerals. Soluble compounds releasing Pb, Zn2+, Pb2+, and Fe2+/3+ are also contained. When anglesite co-exists, lead activation of sphalerite occurred, and thus sphalerite was recovered together with chalcopyrite as froth. To remove soluble compounds (e.g., anglesite) that have detrimental effects on the separation efficiency of chalcopyrite and sphalerite, surface cleaning pretreatment using ethylene diamine tetra acetic acid (EDTA) was applied before flotation. Although most of anglesite were removed and the recovery of chalcopyrite was improved from 19% to 81% at 20 g/t potassium amyl xanthate (KAX) after EDTA washing, the floatability of sphalerite was not suppressed. When zinc sulfate was used as a depressant for sphalerite after EDTA washing, the separation efficiency of chalcopyrite and sphalerite was improved due to deactivation of lead-activated sphalerite by zinc sulfate. The proposed flotation procedure of SMS ores—a combination of surface cleaning with EDTA to remove anglesite and the depression of lead-activated sphalerite by using zinc sulfate—could achieve the highest separation efficiency of chalcopyrite and sphalerite; that is, at 200 g/t KAX, the recoveries of chalcopyrite and sphalerite were 86% and 17%, respectively. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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11 pages, 3801 KiB  
Article
Flotation Separation of Chalcopyrite and Molybdenite Assisted by Microencapsulation Using Ferrous and Phosphate Ions: Part I. Selective Coating Formation
by Ilhwan Park, Seunggwan Hong, Sanghee Jeon, Mayumi Ito and Naoki Hiroyoshi
Metals 2020, 10(12), 1667; https://0-doi-org.brum.beds.ac.uk/10.3390/met10121667 - 13 Dec 2020
Cited by 19 | Viewed by 2449
Abstract
Porphyry Cu-Mo deposits, which are the most important sources of copper and molybdenum, are typically processed by flotation. In order to separate Cu and Mo minerals (mostly chalcopyrite and molybdenite), the strategy of depressing chalcopyrite while floating molybdenite has been widely adopted by [...] Read more.
Porphyry Cu-Mo deposits, which are the most important sources of copper and molybdenum, are typically processed by flotation. In order to separate Cu and Mo minerals (mostly chalcopyrite and molybdenite), the strategy of depressing chalcopyrite while floating molybdenite has been widely adopted by using chalcopyrite depressants, such as NaHS, Na2S, and Nokes reagent. However, these depressants are potentially toxic due to their possibility to emit H2S gas. Thus, this study aims at developing a new concept for selectively depressing chalcopyrite via microencapsulation while using Fe2+ and PO43− forming Fe(III)PO4 coating. The cyclic voltammetry results indicated that Fe2+ can be oxidized to Fe3+ on the chalcopyrite surface, but not on the molybdenite surface, which arises from their different electrical properties. As a result of microencapsulation treatment using 1 mmol/L Fe2+ and 1 mmol/L PO43−, chalcopyrite was much more coated with FePO4 than molybdenite, which indicated that selective depression of chalcopyrite by the microencapsulation technique is highly achievable. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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8 pages, 3231 KiB  
Article
Hydrochloric Acid Leaching Behaviors of Copper and Antimony in Speiss Obtained from Top Submerged Lance Furnace
by Sujin Chae, Kyoungkeun Yoo, Carlito Baltazar Tabelin and Richard Diaz Alorro
Metals 2020, 10(10), 1393; https://0-doi-org.brum.beds.ac.uk/10.3390/met10101393 - 20 Oct 2020
Cited by 4 | Viewed by 3682
Abstract
Copper (Cu) has been recovered from speiss generated from top submerged lance furnace process, but it was reported that the leaching efficiency of Cu in sulfuric acid solution decreased with increasing antimony (Sb) content in the speiss. Scanning electron microscopy (SEM)–energy-dispersive X-ray spectroscopy [...] Read more.
Copper (Cu) has been recovered from speiss generated from top submerged lance furnace process, but it was reported that the leaching efficiency of Cu in sulfuric acid solution decreased with increasing antimony (Sb) content in the speiss. Scanning electron microscopy (SEM)–energy-dispersive X-ray spectroscopy (EDS) results indicate that Sb exists as CuSb alloy, which would retard the leaching of Cu. Therefore, hydrochloric acid leaching with aeration was performed to investigate the leaching behaviors of copper and antimony. The leaching efficiency of Cu increased with increasing agitation speed, temperature, HCl concentration, and the introduction ratio of O2, but also with decreasing pulp density. The leaching efficiency of Cu increased to more than 99% within 60 min in 1 mol/L HCl solution at 600 rpm and 90 °C with 10 g/L pulp density and 1000 cc/min O2. The leaching efficiency of Sb increased and then decreased in all 1 mol/L HCl leaching tests, and precipitate was observed in the leach solution, which was determined to be SbOCl or Sb2O3 by XRD analyses. However, in 2 mol/L–5 mol/L HCl solutions, the leaching efficiency of Sb increased to more than 95% (about 900 mg/L) and remained, so more than 2 mol/L HCl could stabilize Sb ion in the HCl solution. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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11 pages, 3810 KiB  
Article
Fine Bauxite Recovery Using a Plate-Packed Flotation Column
by Pengyu Zhang, Saizhen Jin, Leming Ou, Wencai Zhang and Yuteng Zhu
Metals 2020, 10(9), 1184; https://0-doi-org.brum.beds.ac.uk/10.3390/met10091184 - 02 Sep 2020
Cited by 3 | Viewed by 2226
Abstract
In this investigation, the fine-grained bauxite ore flotation was conducted in a plate-packed flotation column. This paper evaluated the effects of packing-plates on recovering fine bauxite particles and revealed the fundamental mechanisms. Bubble coalescence and break-up behaviors in the packed and unpacked flotation [...] Read more.
In this investigation, the fine-grained bauxite ore flotation was conducted in a plate-packed flotation column. This paper evaluated the effects of packing-plates on recovering fine bauxite particles and revealed the fundamental mechanisms. Bubble coalescence and break-up behaviors in the packed and unpacked flotation columns were characterized by combining Computational Fluid Dynamics (CFD) and Population Balance Model (PBM) techniques. Flotation experiments showed that packing-plates in the collection zone of a column can improve bauxite flotation performance and increase the smaller bauxite particles recovery. Using packing-plates, the recovery of Al2O3 increased by 2.11%, and the grade of Al2O3 increased by 1.85%. The fraction of −20 μm mineral particles in concentrate increased from 47.31% to 54.79%. CFD simulation results indicated that the packing-plates optimized the bubble distribution characteristics and increased the proportion of microbubbles in the flotation column, which contributed to improving the capture probability of fine bauxite particles. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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10 pages, 2515 KiB  
Article
Agglomeration–Flotation of Finely Ground Chalcopyrite Using Emulsified Oil Stabilized by Emulsifiers: Implications for Porphyry Copper Ore Flotation
by Vothy Hornn, Mayumi Ito, Hiromasa Shimada, Carlito Baltazar Tabelin, Sanghee Jeon, Ilhwan Park and Naoki Hiroyoshi
Metals 2020, 10(7), 912; https://0-doi-org.brum.beds.ac.uk/10.3390/met10070912 - 08 Jul 2020
Cited by 23 | Viewed by 2738
Abstract
Flotation is the conventional method for processing porphyry copper deposits, one of the most economically important sources of copper (Cu) worldwide. The rapidly decreasing grade of this type of Cu ore in recent years, however, presents serious problems with fine particle recovery using [...] Read more.
Flotation is the conventional method for processing porphyry copper deposits, one of the most economically important sources of copper (Cu) worldwide. The rapidly decreasing grade of this type of Cu ore in recent years, however, presents serious problems with fine particle recovery using conventional flotation circuits. This low recovery could be attributed to the low collision efficiency of fine particles and air bubbles during flotation. To improve collision efficiency and flotation recovery, agglomeration of finely ground chalcopyrite (CuFeS2) (D50 = 3.5 μm) using emulsified oil stabilized by emulsifiers was elucidated in this study. Specifically, the effects of various types of anionic (sodium dodecyl sulfate (SDS), potassium amyl xanthate (KAX)), cationic (dodecyl amine acetate (DAA)), and non-ionic (polysorbate 20 (Tween 20)) emulsifiers on emulsified oil stability and agglomeration–flotation efficiency were investigated. When emulsifiers were added, the average size of agglomerates increased, resulting in higher Cu recovery during flotation. This dramatic improvement in flotation efficiency could be attributed to the smaller oil droplet size in emulsified oil and their higher stability in the presence of emulsifiers. The utilization of emulsifiers during agglomeration–flotation not only lowered the required agitation strength for agglomeration but also shortened the agglomeration time, both of which made the process easier to incorporate in existing flotation circuits. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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Review

Jump to: Editorial, Research

26 pages, 6890 KiB  
Review
A Review of Recent Advances in Depression Techniques for Flotation Separation of Cu–Mo Sulfides in Porphyry Copper Deposits
by Ilhwan Park, Seunggwan Hong, Sanghee Jeon, Mayumi Ito and Naoki Hiroyoshi
Metals 2020, 10(9), 1269; https://0-doi-org.brum.beds.ac.uk/10.3390/met10091269 - 21 Sep 2020
Cited by 33 | Viewed by 4783
Abstract
Porphyry copper deposits (PCDs) are some of the most important sources of copper (Cu) and molybdenum (Mo). Typically, the separation and recovery of chalcopyrite (CuFeS2) and molybdenite (MoS2), the major Cu and Mo minerals, respectively, in PCDs are achieved [...] Read more.
Porphyry copper deposits (PCDs) are some of the most important sources of copper (Cu) and molybdenum (Mo). Typically, the separation and recovery of chalcopyrite (CuFeS2) and molybdenite (MoS2), the major Cu and Mo minerals, respectively, in PCDs are achieved by two-step flotation involving (1) bulk flotation to separate Cu–Mo concentrates and tailings (e.g., pyrite, silicate, and aluminosilicate minerals) and (2) Cu–Mo flotation to separate chalcopyrite and molybdenite. In Cu–Mo flotation, chalcopyrite is depressed using Cu depressants, such as NaHS, Na2S, Nokes reagent (P2S5 + NaOH), and NaCN, meaning that it is recovered as tailings, while molybdenite is floated and recovered as froth product. Although conventionally used depressants are effective in the separation of Cu and Mo, they have the potential to emit toxic and deadly gases such as H2S and HCN when operating conditions are not properly controlled. To address these problems caused by the use of conventional depressants, many studies aimed to develop alternative methods of depressing either chalcopyrite or molybdenite. In this review, recent advances in chalcopyrite and molybdenite depressions for Cu–Mo flotation separation are reviewed, including alternative organic and inorganic depressants for Cu or Mo, as well as oxidation-treatment technologies, such as ozone (O3), plasma, hydrogen peroxide (H2O2), and electrolysis, which create hydrophilic coatings on the mineral surface. Full article
(This article belongs to the Special Issue Advances in Selective Flotation and Leaching Process in Metallurgy)
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