Mineral sulphide-lime reactions and effect of CaO/C mole ratio during carbothermic reduction of complex mineral sulphides

Hara, Yotamu R. S.

doi:10.1007/s12613-014-0858-0

Cited by 10 publications

(7 citation statements)

References 6 publications

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“…This phase is an intermediate phase during ion exchange reaction and confirms a great progress in this reaction at 750 °C. Formation of oxysulfide phases is also reported during carbothermic reduction of sulfide minerals in the presence of lime in previous studies [3,6,12] . Fig.…”

Section: Methodssupporting

confidence: 63%

“…On the other hand, reduction rate of iron oxide in H2 is much higher than that in CO [4,5] . Accordingly, hydrogen-reduction of FeS in the presence of lime is likely an alternative method for iron production from iron sulfide minerals that can be considered as a twostage reaction [6] ; ion exchange reaction, Eq. (1), and reduction reaction, Eq.…”

Section: Introductionmentioning

confidence: 99%

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H2-reduction Behavior of FeS-CaO Mixture during Microwave Heating

Amini

Ohno

Maeda

et al. 2019

Proceedings 17th International Conference on Microwave and High Frequency Heating

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Microwave irradiation is an energy-efficient and a rapid-heating method to decrease the activation energy of chemical reactions via both thermal and non-thermal effects of microwave photons 1). Recently, hydrogen-reduction during microwave heating has been proposed for magnetite reduction to combine the advantages of microwave irradiation and using H2 as a reducing agent during iron production 2). In the present study, as a novel idea, the traditional microwave heating system was equipped with thermobalance to investigate the kinetics of H2-reduction of FeS-CaO mixture (FeS(s) + CaO(s) + H2(g) = Fe(s) + CaS(s) + H2O(g)) under microwave heating at 2.45 GHz to further mitigate CO2 emission and prevent SO2 release during iron production from a sulfide mineral. Microscope observations revealed that the un-reacted core model can be employed for such a kinetic study. Linearity (R2) of different rate-controlling mechanisms after a 10-minute reduction reaction demonstrated that the gas diffusion in micropores of reduced metallic Fe is a dominant rate-controlling mechanism while the interfacial chemical reaction is progressed rapidly. This is attributed to extraordinary effects of microwave irradiation on speeding up the chemical reactions 3), while the formation of Fe shell on the surface of FeS/FeO particles decreases the accessibility of gas to un-reacted parts, resulting in a lower rate of gas diffusion in micropores. Moreover, the diffusion coefficients (De) at 460, 570, and 750 °C were calculated from the plot of the gas diffusion, as illustrated in Fig. 1, wherein the X is reduction degree: where Wi (g) is the initial weight of the sample, Wt (g) is the weight of the sample after treatment for t seconds, Wht (g) is the weight change of the sample owing to the dehydration reaction, and WO (-) is the stoichiometric weight ratio of oxygen in the sample, which is 0.111. Consequently, the activation energy of 22.3 kJ.mol-1 was attained from the Arrhenius equation for the hydrogen-reduction reaction of FeS-CaO mixture under microwave heating.

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Section: Methodssupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

H2-reduction Behavior of FeS-CaO Mixture during Microwave Heating

Amini

Ohno

Maeda

et al. 2019

Proceedings 17th International Conference on Microwave and High Frequency Heating

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show abstract

“…[16][17][18][19] On the other hand, higher stability of the metal oxide than metal sulfide demonstrates a greater reactivity of mineral sulfide in an ion exchange reaction. 2) For example, the Gibbs free energy of the ion exchange reaction between FeS and CaO is negative indicating higher stability of the FeO than FeS. Furthermore, metallization of Fe is restricted by the reduction reaction owing to a higher stability of FeO than metallic iron.…”

Section: Fesmentioning

confidence: 99%

“…1) Lime (CaO) has a high tendency for reaction with sulfur to form CaSO 4 and CaS in the oxidizing and reducing atmosphere, respectively. 2,3) Hara et al 3) reported the production of Cu, Co and Fe after a carbothermic reduction of sulfide concentrate containing copper, cobalt, and iron in the presence of CaO at 1 000°C. Also, Hara et al 4) has studied the reduction of a mineral sulfide-CaO-C mixture and demonstrated that an increase in mole ratio of C:CaO improves magnetic separation of products into metal and CaS.…”

Section: Introductionmentioning

confidence: 99%

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Carbothermic Reduction Behavior of FeS in the Presence of CaO during Microwave Irradiation

et al. 2019

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Carbothermic reduction of FeS in the presence of CaO was experimentally studied by employing a multimode microwave generator at 1 050 W and 2.45 GHz as an external heat source to mitigate CO 2 and SO 2 emissions. According to XRD analysis, an ion exchange reaction between FeS and CaO was initiated at temperatures lower than 645°C and progressed by a further heating to 850°C without any evidence for the onset of a reduction reaction. Detection of Fe phase in the XRD pattern of sample heated to 920°C and existence of CO/CO 2 in the off-gas during microwave treatment demonstrated that the reduction reaction initiates at ca. 850°C. It was found that the onset of reduction reaction promotes the ion exchange reaction by FeO consumption via reduction to Fe. Moreover, optical microscope and SEM-EDX observations showed that carbon can be absorbed by metallic iron to make molten iron particles at 1 290°C.

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Energy Efficient Separation of Magnetic Alloy fron the Carbothermic Reduction of NKANA Cu-Co Concentrates

Hara

Jha

2015

Energy Technology 2015

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Mineral sulphide-lime reactions and effect of CaO/C mole ratio during carbothermic reduction of complex mineral sulphides

Cited by 10 publications

References 6 publications

H2-reduction Behavior of FeS-CaO Mixture during Microwave Heating

H2-reduction Behavior of FeS-CaO Mixture during Microwave Heating

Carbothermic Reduction Behavior of FeS in the Presence of CaO during Microwave Irradiation

Energy Efficient Separation of Magnetic Alloy fron the Carbothermic Reduction of NKANA Cu-Co Concentrates

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