Experiments on the simultaneous partitioning of divalent cations between arsenopyrite or cobaltite and hydrothermal chloride solution under supercritical conditions

Uchida, Etsuo; Izumi, Yuya; Watanabe, Hikaru

doi:10.2465/gkk.181112

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…The activity coefficient of the i aqueous species was set to 1 for neutral aqueous species and was calculated using the Debye-Hückel equation for other charged aqueous species (e.g., [20]). The molality of each aqueous species can be obtained by simultaneously solving the mass balance Equations ( 8)- (10) and the mass action Equations ( 11)- (13). The data of Frantz and Marshall [21] were used for the dissociation constants of MgCl + aq in the Equation ( 11) and MgCl 2 0 aq in the Equation (12).…”

Section: Discussion 41 Ion-exchange Reaction and Aqueous Neutral Spec...mentioning

confidence: 99%

“…Such a negative distribution anomaly of Zn 2+ was not observed in sphalerite, which is a sulfide mineral with a fourfold coordinated site [16]. However, in arsenopyrite, cobaltite, alabandite, löllingite, and sufflorite, which are sulfide or arsenide minerals with sixfold coordinated sites, the negative distribution anomaly of Zn 2+ is remarkable [11][12][13][14]. The appearance of a distribution anomaly for minerals with sixfold coordinated sites indicates that Zn 2+ prefers the fourfold coordinated sites, as explained from the ligand field theory, showing normal distribution behavior in the four-fold coordinated sites, whereas entry into sixfold coordinated sites is difficult for Zn 2+ .…”

Section: Distribution Coefficient and Pc-ir Diagrammentioning

confidence: 96%

“…Ion-exchange experiments between aqueous chloride solutions and sulfide minerals (pyrite, pyrrhotite, sphalerite, and alabandite), arsenic sulfide minerals (arsenopyrite and cobaltite), and arsenide minerals (löllingite and sufflorite) were conducted by Uchida et al [12][13][14][15][16]. Covalent bonds predominate in these minerals, and their electronegativity has been shown to influence the element distribution.…”

Section: Introductionmentioning

confidence: 99%

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Experiments on Distribution of Divalent Metal Cations between Olivine Solid Solutions and Aqueous Chloride Solutions at 700 °C and 100 MPa

Uchida

Ohashi

2022

Minerals

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Experiments on divalent cation distribution between Mg–Fe olivine solid solutions and 1 mol/L (Ni2+, Mg2+, Co2+, Zn2+, Fe2+, Mn2+)Cl2 aqueous solutions were carried out at 700 °C and 100 MPa. Regardless of the composition of the Mg–Fe olivine solid solutions, the tendency of divalent cation distribution into the olivine solid solutions against the aqueous chloride solutions was in the order of Ni2+ > Mg2+ > Co2+ > Mn2+ > Fe2+ > Zn2+. Excluding Zn2+, this order corresponds to the order of the sixfold coordinated ionic radius in olivine. This indicates that a smaller ionic radius allows the cation to more easily enter the olivine solid solutions. However, Zn2+ showed a negative distribution anomaly and did not easily enter the sixfold coordinated site of the olivine solid solutions, regardless of the ionic radius. This is because Zn2+ has a strong preference for fourfold coordinated sites. The Mg–Fe olivine solid solutions with more fayalite endmembers have smaller differences in the distribution coefficient of cations. This means that the gradient of the PC–IR curve becomes smaller as the content of fayalite endmembers increases. This trend indicates that fayalite consisting of a large cation (Fe2+) tends to exchange other cations more easily than forsterite consisting of a small cation (Mg2+).

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Section: Discussion 41 Ion-exchange Reaction and Aqueous Neutral Spec...mentioning

confidence: 99%

Section: Distribution Coefficient and Pc-ir Diagrammentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Experiments on Distribution of Divalent Metal Cations between Olivine Solid Solutions and Aqueous Chloride Solutions at 700 °C and 100 MPa

Uchida

Ohashi

2022

Minerals

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Experimental investigation of the simultaneous partitioning of divalent cations between löllingite or safflorite and 2 mol/L aqueous chloride solutions under supercritical conditions

Uchida

Sugino

Yokoyama

2020

Journal of Mineralogical and Petrological Sciences

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In order to elucidate partition behavior of divalent cations between minerals and aqueous chloride solutions under supercritical conditions of fluid phase, we conducted experiments of the simultaneous partitioning of Ni 2+ , Mg 2+ , Co 2+ , Zn 2+ , Fe 2+ , and Mn 2+ between löllingite (FeAs 2 ) or safflorite (CoAs 2 ) and 2 mol/L aqueous chloride solutions under the conditions of 500 and 600°C, 100 MPa. Natural löllingite and safflorite were used as starting materials. The bulk partition coefficient (K PB ) for the cation partition reactions can be expressed as follows:where x MeAs2 indicates the molar fraction of each end-member in the solid phase. m Meaq is the total molar concentration of Me-bearing aqueous species in aqueous chloride solution. For the experiments using löllingite, the order of partition coefficients of divalent cations was:

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Simultaneous Partitioning of Divalent Metal Ions between Alabandite and 1 mol/L (Ni, Mg, Co, Zn, Fe)Cl2 Aqueous Solutions under Supercritical Conditions

2020

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To clarify the element partitioning behavior between minerals and aqueous chloride solutions, we conducted experiments to investigate simultaneous partitioning of Ni2+, Mg2+, Co2+, Zn2+, Fe2+, and Mn2+ ions between alabandite (MnS) and 1 mol/L (Ni, Mg, Co, Zn, Fe)Cl2 aqueous solutions at 500–800 °C and 100 MPa. The bulk partition coefficients calculated using the following equation were in the order of Fe2+ > Co2+ > Ni2+ ≈ Zn2+ > Mn2+ >> Mg2+; KPN = (xMeS/mMeaq)/(xMnS/mMnaq). A partition coefficient-ionic radius (PC-IR) curve was plotted with the logarithmic value of the partition coefficient on the y-axis and the ionic radius at the six-fold coordinated site on the x-axis. The peak of this curve was located near the ionic radius of Fe2+ and not near the ionic radius of Mn2+. Zn2+ showed a slight negative partitioning anomaly, which increased in the order of sulfide minerals < arsenic sulfide minerals < arsenide minerals as the covalent bond became stronger. Ni2+ showed a positive partitioning anomaly, which indicated that it preferred an octahedral structure. The width of the PC-IR curve decreased in the order of sulfide minerals > arsenic sulfide minerals > arsenide minerals as the covalent bond became stronger, that is, the ion selectivity became stronger.

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Experiments on the simultaneous partitioning of divalent cations between arsenopyrite or cobaltite and hydrothermal chloride solution under supercritical conditions

Cited by 4 publications

References 7 publications

Experiments on Distribution of Divalent Metal Cations between Olivine Solid Solutions and Aqueous Chloride Solutions at 700 °C and 100 MPa

Experiments on Distribution of Divalent Metal Cations between Olivine Solid Solutions and Aqueous Chloride Solutions at 700 °C and 100 MPa

Experimental investigation of the simultaneous partitioning of divalent cations between löllingite or safflorite and 2 mol/L aqueous chloride solutions under supercritical conditions

Simultaneous Partitioning of Divalent Metal Ions between Alabandite and 1 mol/L (Ni, Mg, Co, Zn, Fe)Cl2 Aqueous Solutions under Supercritical Conditions

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