Leaching of pure and cobalt bearing goethites in sulphurous acid: kinetics and mechanisms

Kumar, Rakesh; Das, S; Ray, R. K.; Biswas, Arindam

doi:10.1016/0304-386x(93)90055-i

Cited by 34 publications

(11 citation statements)

References 19 publications

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“…Three synthetic goethite samples were prepared by the precipitation of a hydroxide gel from a solution containing Fe(NO 3 ) 3 .9H 2 O using the published procedure (Kumar et al, 1993 were air dried at 60°C and allowed to stand at room temperature before being placed in sample bottles and stored under ambient conditions. The colour of the prepared solids varied slightly, with the co-precipitated solids being slightly darker than the sample which contained only iron.…”

Section: Methodsmentioning

confidence: 99%

“…However, the reaction mechanism in scheme 6 does not consider the electrontransfer step for the oxidation of SO 2 or HSO 3 -to S 2 O 6 2-(dithionate) or HSO 3 radical, which are further oxidised to HSO 4 -/SO 4 2- (Kumar et al, 1993;Das et al, 1997;Zhang et al, 2000;Senanayake, 2003a;Das and de Lange, 2011). This warrants further discussion of the rates of iron dissolution from different oxide systems on the basis of surface active sulphur species in the adsorption/reaction mechanisms listed in Table 12 to rationalise the leaching behaviour of iron.…”

Section: Eh-ph Diagram and Ratesmentioning

confidence: 99%

“…XRD pattern for laterite (1) ore (K α Co (λ=1.788965 Å), see Table 6 for standard cards numbers). (Table 9), Surana and Warren (1969) and Kumar et al (1993). Nan and Lawson,1989 (c), HSC 6.1 (d,e), Sillen andMartell, 1964, Hogfeldt, 1982 (f,g).…”

Section: Shrinking Core Kineticsmentioning

confidence: 99%

“…XRD patterns for synthetic goethite with no additives (1), nickel spiked (2) and cobalt spiked (3) ( K α Co ( λ = 1.788965 Å); see Table 6 for standard card numbers). (Table 9), Surana and Warren (1969) and Kumar et al (1993). Nan and Lawson,1989 (c), HSC 6.1 (d,e), Sillen andMartell, 1964, Hogfeldt, 1982 (f,g The value in parentheses show the surface area of limonitic ore with a porosity of 0.708 subjected to PAL process by Gergeou and Papangelakis (1998).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

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Reductive acid leaching of laterite and metal oxides — A review with new data for Fe(Ni,Co)OOH and a limonitic ore

et al. 2011

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The reductive leaching of nickel laterite has attracted the interest of many researchers due to the enhanced kinetics of nickel and cobalt dissolution in the presence of acids and reducing agents during atmospheric, pressure, heap or bio leaching processes. Systematic studies on synthetic oxides and natural ores can shed light on the reaction mechanism and lead to investigations of beneficial reagents for further studies. This paper briefly reviews the literature and describes a comparative study of metal leaching from synthetic goethite spiked with nickel or cobalt and a limonitic laterite ore to rationalise the role of reducing agents in acid media. Results are discussed on the basis of the effect of speciation, surface chemical reactivity of oxides and heterogeneous kinetic models.Key words: Laterite, synthetic oxides, reductive leaching, kinetics, adsorption. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

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Section: Methodsmentioning

confidence: 99%

Section: Eh-ph Diagram and Ratesmentioning

confidence: 99%

Section: Shrinking Core Kineticsmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

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Reductive acid leaching of laterite and metal oxides — A review with new data for Fe(Ni,Co)OOH and a limonitic ore

et al. 2011

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“…[10] Little or no attempt has been made to compare the available kinetic data for the reduction of goethite, [6] magnetite, [7] and laterite [1] by SO 2 under a range of leaching conditions, which gave the results shown in Table I and Figure 1. The effect of some of these parameters has been successfully incorporated into the well-known shrinking sphere model, which is useful for kinetic modeling and reactor design: [11] [1]…”

mentioning

confidence: 99%

A surface reaction kinetic model to compare the reductive leaching of iron from goethite, magnetite, and limonitic nickel laterite ores by acidic sulfur dioxide

Senanayake

2003

Metall Mater Trans B

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The kinetic modeling of iron dissolution at low pH in the presence of SO 2 or Na 2 SO 3 is of particular interest due to the fact that iron oxides are major components in limonitic nickel laterite ores, [1] deep sea nodules, [2] weathered rare earth (RE) mud, [3] and manganiferrous ores, [4] and are common to many soils. [5] Table I lists the conditions under which the leaching experiments have been carried out by previous researchers and the pct Fe extracted from different types of iron oxide materials. The reactivity of hematite is 1/10th that of goethite, magnetite, and laterite, as shown by the pct Fe leached in 1 hour. Despite the different iron contents and the leaching conditions in the case of laterite and RE mud, the pct Fe extracted in 2 hours is similar. The relatively high reactivity of the mud at low temperature is most likely attributed to finely divided iron oxide in the particle. Nevertheless, the low rates of iron dissolution from hematite in RE mud, particularly at low pH and low SO 2 concentrations, show the selective leaching of manganese. [3] Figure 1 compares the fraction of iron leached from variously sized particles of goethite and magnetite as a function of time; the slope represents the rate of leaching. Despite the lower temperature of 20°C, the leaching of the ultra fine (0.1 m) goethite is much faster than the leaching of coarse (150 m) goethite at 110°C, which is nearly the same as that of 75-m magnetite at 50°C.Previous attempts to rationalize the kinetics of reductive leaching of iron oxides were based on the adsorption theory [5,6,7] and electrochemical studies [8,9] with limited success in some investigations. [10] Little or no attempt has been made to compare the available kinetic data for the reduction of goethite, [6] magnetite, [7] and laterite [1] by SO 2 under a range of leaching conditions, which gave the results shown in Table I and Figure 1. The effect of some of these parameters has been successfully incorporated into the well-known shrinking sphere model, which is useful for kinetic modeling and reactor design: [11] [1]where X ϭ fraction of Fe reacted at time t (s), k ϭ intrinsic rate constant of the surface reaction (cm s Ϫ1 ), r ϭ initial particle radius of solid (cm), ϭ molar density of Fe in the solid (mol cm Ϫ3 ), k ss ϭ apparent rate constant (s Ϫ1 ), andϪ ] n r Ϫ1 r Ϫ1 t ϭ k ss t m, n ϭ reaction order with respect to [H ϩ ] and [HSO 3 Ϫ ] in equilibrium with SO 2 :The shrinking sphere model takes into account the decrease in particle size and thus the surface area with time. In general, the value of k ss is obtained from the slope of a plot of 1 Ϫ (1 Ϫ X) 1/3 against t. This is used in the Arrhenius equation, k ss ϭ A exp (ϪE/RT), to examine the effect of temperature for leaching under a given set of conditions (r, , [SO 2 ], pulp density, and sufficient agitation to avoid masstransfer limitations to the surface), and to determine the activation energy E and the Arrhenius constant A. The use of the intrinsic rate constant k, instead of k ss , in the Arrhenius...

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Pretreatment by electrolytic or oxidative leaching for recovery of gold and silver from refractory sulphide concentrates

Abrantes¹,

Costa²,

Paiva³

1994

Hydrometallurgy ’94

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Leaching of pure and cobalt bearing goethites in sulphurous acid: kinetics and mechanisms

Cited by 34 publications

References 19 publications

Reductive acid leaching of laterite and metal oxides — A review with new data for Fe(Ni,Co)OOH and a limonitic ore

Reductive acid leaching of laterite and metal oxides — A review with new data for Fe(Ni,Co)OOH and a limonitic ore

A surface reaction kinetic model to compare the reductive leaching of iron from goethite, magnetite, and limonitic nickel laterite ores by acidic sulfur dioxide

Pretreatment by electrolytic or oxidative leaching for recovery of gold and silver from refractory sulphide concentrates

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