Effect of solution composition on the optimum redox potential for chalcopyrite leaching in sulfuric acid solutions

Hiroyoshi, Naoki; Kitagawa, Hiroko; Tsunekawa, Masami

doi:10.1016/j.hydromet.2007.12.005

Cited by 82 publications

(46 citation statements)

References 15 publications

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“…High values obtained (Figure 3a) indicate the initial stage of chalcopyrite leaching is controlled by surface chemical reaction [4,22,23,25,43]. The values derived from leaching at pH 1.0 (with and without iron addition), 1.5 and 2.0 (without aqueous iron addition) are within the error range.…”

Section: Effect Of 4 Mmol Iron Additionmentioning

confidence: 53%

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Wei

Qian

et al. 2016

Minerals

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Abstract:To better understand chalcopyrite leach mechanisms and kinetics, for improved Cu extraction during hydrometallurgical processing, chalcopyrite leaching has been conducted at solution redox potential 750 mV, 35-75˝C, and pH 1.0 with and without aqueous iron addition, and pH 1.5 and 2.0 without aqueous iron addition. The activation energy (E a ) values derived indicate chalcopyrite dissolution is initially surface chemical reaction controlled, which is associated with the activities of Fe 3+ and H + with reaction orders of 0.12 and´0.28, respectively. A surface diffusion controlled mechanism is proposed for the later leaching stage with correspondingly low E a values. Surface analyses indicate surface products (predominantly S n 2´a nd S 0 ) did not inhibit chalcopyrite dissolution, consistent with the increased surface area normalised leach rate during the later stage. The addition of aqueous iron plays an important role in accelerating Cu leaching rates, especially at lower temperature, primarily by reducing the length of time of the initial surface chemical reaction controlled stage.

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Section: Effect Of 4 Mmol Iron Additionmentioning

confidence: 53%

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Wei

Qian

et al. 2016

Minerals

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“…Several authors have described the positive effect of both redox potential and ferrous ions on chalcopyrite dissolution, however attributing different significance of each one 7,9,10,21,24,25,26 . For instance, Third et al 21 considered the redox potential a parameter more significant to determine chalcopyrite leaching rates than bacterial cell number or their activity.…”

Section: Leaching Experimentsmentioning

confidence: 99%

“…One of the solutions discussed to overcome this issue considers the control of redox potential throughout (bio)leaching processes that could be achieved either electrochemically by applying a redox potential from an external source through a working electrode or chemically by the addition of reducing and oxidizing agents 7 . The maintenance of the redox potential in a narrow range is discussed by Hiroyoshi and colleagues 9,10 .…”

Section: Introductionmentioning

confidence: 99%

“…The authors described a greater metal recovery in solutions with different ferrous, ferric and cupric ions concentrations 9 . The presence of certain concentrations of these ions in solution allowed the maintenance of an optimum redox potential for copper recovery due to formation of less refractory copper intermediates than chalcopyrite, such as chalcocite (Cu 2 S).…”

Section: Introductionmentioning

confidence: 99%

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Effect of redox potential on chalcopyrite dissolution imposed by addition of ferrous ions

et al. 2017

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ABSTRACT:Copper is one of the metals with great economic interest and about 70% of it is found in nature as chalcopyrite mineral (CuFeS 2 ). Due to its slow dissolution kinetics, chalcopyrite dissolution is still a challenge for industries and researchers. Control of redox potential though has been said to be the key for increasing dissolution rate in chalcopyrite leaching systems. The current work investigated the effect of redox potential by ferrous ions addition on chalcopyrite (bio)leaching experiments. In abiotic systems, 90% of copper was leached into solution when redox potential was kept low (around 420 mV/Ag/AgCl) whereas in bacterial systems (610 mV/Ag/AgCl) low copper dissolution was observed. SEM analysis suggested presence of new phases that were confirmed by XRD to be elemental sulfur and jarosites and a significant decrease of chalcopyrite peak heights in these analyses was also observed. Jarosite was the only new phase detected in bacterial systems. Passivation of chalcopyrite surface did not occur in either conditions. The results clearly show that low redox potential along with presence of ferrous ions has positively influenced copper recovery, confirming the existence of a critical redox potential range where chalcopyrite dissolution is favored.

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“…4 In acidic media (sulfuric, hydrochloric and nitric acid), the concentrate can be leached under atmospheric or elevated pressures. [8][9][10][11][12][13][14] Among them, the most promising one is sulfuric acid, since it can be readily produced at lower costs as the ore and, hence, the concentrate contain considerable amounts of sulphur.…”

Section: Introductionmentioning

confidence: 99%

Improvement of selective copper extraction from a heat-treated chalcopyrite concentrate with atmospheric sulphuric-acid leaching

Uzun¹,

Mustafa²,

Atilgan³

2016

Mater. Tehnol.

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The present work focuses on the extraction of Cu, suitable for production, directly from a leach solution of a chalcopyrite concentrate as an alternative to the conventional smelting and refining method. Firstly, the main aspects of the kinetics of chalcopyrite leaching in a sulphuric-acid solution and transformation reactions of chalcopyrite at high temperatures were briefly reviewed. Secondly, atmospheric-acid leaching experiments were performed as a function of the acid content and temperature under agitation. Direct leaching experiments resulted in very low and scattered Cu recoveries, hence revealing a sulphide passivation layer on the chalcopyrite. In order to get rid of this layer, the sulphides in the chalcopyrite were transformed into sulphates with heat treatment at 500°C prior to the leaching process, in which a high dissolution of species was obtained. Finally, the leaching of the pre-heated concentrate resulted in a 99.82 % Cu extraction. Consequently, optimized process parameters were proposed by comparing the Cu extraction and the increased purity of the pregnant solution without Fe impurities. Keywords: chalcopyrite concentrate, leaching, heat treatment, passivation layer, copper extraction, selectivity Namen tega dela je ekstrakcija bakra (Cu), ki bi bila primerna za neposredno proizvodnjo iz lu`ine koncentrata halkopirita, kot alternative obi~ajni metodi s taljenjem in rafinacijo. Najprej je bil opravljen pregled glavnih vidikov kinetike izlu`evanja halkopirita v raztopini solne kisline in reakcij pretvorbe halkopirita pri visokih temperaturah. Nato so bili izvedeni preizkusi izlu`evanja na zraku v kislini, v odvisnosti od vsebnosti kisline in temperature z me{anjem. Neposredni preizkusi izlu`evanja so pokazali zelo nizko in raztreseno pridobitev bakra, ker se je halkopirit prekril s sulfidnim pasivacijskim slojem. Da bi se tega sloja znebili, so bili sulfidi v halkopiritu pretvorjeni v sulfate, s toplotno obdelavo pri 500°C pred postopkom izlu`evanja, pri katerem je bilo dose`eno dobro raztapljanje vzorca. Kon~no je bilo dose`eno 99,82 % izlu`evanje bakra (Cu) iz predogretega koncentrata. Posledi~no so bili predlagani optimalni parametri procesa s primerjavo ekstrakcije bakra (Cu) in pove~ane~istosti nosilne raztopine brez ne~isto~`eleza (Fe).

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Effect of solution composition on the optimum redox potential for chalcopyrite leaching in sulfuric acid solutions

Cited by 82 publications

References 15 publications

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Effect of redox potential on chalcopyrite dissolution imposed by addition of ferrous ions

Improvement of selective copper extraction from a heat-treated chalcopyrite concentrate with atmospheric sulphuric-acid leaching

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