Dissolution Of Cobalt Research Articles

Kinetics of the dissolution of cobalt, nickel, and iron oxides in sulfuric acid

The modeling of dissolution of cobalt, nickel, and iron oxides in sulfuric acid shows that the rate-determining step of the dissolution is the passage of oxide complexes formed on the surface of oxide particles to a solution. A system analysis of the dissolution curves (α-τ) of the oxides is developed to calculate the kinetic parameters (\(n_{H^ + } \),Ea). Cobalt oxide Co3O4 dissolves in H2SO4 more rapidly than nickel and iron oxides (Ni2O3 and Fe2O3).

Electrochemical impedance spectroscopy of anodic processes on Co2Si electrode in sulfuric acid solutions

Frequency dependences of the impedance of Co2Si electrode in 0.5 M H2SO4 and 0.05 M H2SO4 + 0.45 M Na2SO4 solutions are measured in the ranges of the active dissolution, active-passive transition, passive state, and transpassivity. There are potential values in the active range when the impedance can be interpreted as the impedance of the selective cobalt dissolution. The impedance spectra in the passive range and in the beginning of the transpassive potential range are described with the use of an equivalent circuit taking into account the existence of an oxide layer on the electrode surface.

A copper-catalyzed bioleaching process for enhancement of cobalt dissolution from spent lithium-ion batteries

A copper-catalyzed bioleaching process was developed to recycle cobalt from spent lithium-ion batteries (mainly LiCoO 2) in this paper. The influence of copper ions on bioleaching of LiCoO 2 by Acidithiobacillus ferrooxidans ( A.f) was investigated. It was shown that almost all cobalt (99.9%) went into solution after being bioleached for 6 days in the presence of 0.75 g/L copper ions, while only 43.1% of cobalt dissolution was obtained after 10 days without copper ions. EDX, XRD and SEM analyses additionally confirmed that the cobalt dissolution from spent lithium-ion batteries could be improved in the presence of copper ions. The catalytic mechanism was investigated to explain the enhancement of cobalt dissolution by copper ions, in which LiCoO 2 underwent a cationic interchange reaction with copper ions to form CuCo 2O 4 on the surface of the sample, which could be easily dissolved by Fe 3+.

Decomposition Mechanism and Decomposition Promoting Factors of Waste Hard Metal for Zinc Decomposition Process (ZDP)

Decomposition promoting factors and decomposition mechanism in the zinc decomposition process of waste hard metals which are composed mostly of tungsten carbide and cobalt were evaluated. Zinc volatility amount was suppressed and zinc steam pressure was produced in the reaction graphite crucible inside an electric furnace for ZDP. Reaction was done for 2 hrs at 650 °C, which 100 % decomposed the waste hard metals that were over 30 mm thick. As for the separation-decomposition of waste hard metals, zinc melted alloy formed a liquid composed of a mixture of γ-β1 phase from the cobalt binder layer (reaction interface). The volume of reacted zone was expanded and the waste hard metal layer was decomposed-separated horizontally from the hard metal. Zinc used in the ZDP process was almost completely removed-collected by decantation and volatilization-collection process at 1000 °C. The small amount of zinc remaining in the tungsten carbide-cobalt powder which was completely decomposed was fully removed by using phosphate solution which had a slow cobalt dissolution speed.

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

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.

UV/visible spectroscopic analysis of CO3+ and CO2+ during the dissolution of cobalt from mixed Co-Cu oxidized ores

The leaching of cobalt from four-mixed Co-Cu oxidized ores containing cobalt at levels ranging from 0.5wt% to 34wt% was studied and the results has been reported. Conventional dissolution of these oxidized Co-Cu ores with diluted H2SO4 and SO2 as a reducing agent resulted in a substantial improvement in the solution based recovery of cobalt. UV/visible spectroscopic analysis of the leached solutions indicated that the increased cobalt content in the solution was a result of flushing the acidified cobalt leaching solution with SO2. Furthermore, UV/visible spectroscopy confirmed that as SO2 was flushed into the acidified leaching solution, Co3+ bearing minerals were reduced to the readily soluble Co2+ bearing minerals, and this resulted in the increase of total cobalt in the collected solution. The mechanism of the reduction of Co3+ to Co2+ bearing minerals when SO2 is flushed during the leaching of mixed Co-Cu oxidized ores, including the stability trends of Co3+, Co2+, and Cu2+ complexes, as shown by their UV/visible spectra, are also discussed.

Bioleaching of flotation by-products of talc production permits the separation of nickel and cobalt from iron and arsenic

Arsenic and iron can be found as impurities in nickel- and cobalt-containing flotation by-products of talc production. This study examined whether bioleaching could directly produce solutions containing nickel and cobalt but not iron and arsenic. In shake flasks, nickel and cobalt were over 99% dissolved from a nickel-rich flotation concentrate (NFC) and an arsenic rich flotation concentrate (GFC) around pH 3.0. During bioleaching of NFC (10% pulp density), arsenic remained below 20 mg/l and dissolved iron reached a maximum of 3.6 g/l. During bioleaching of GFC (10% pulp density), arsenic reached 4 g/l and dissolved iron remained below 20 mg/l. Decreasing the temperature from 27 to 6 °C reduced nickel and cobalt dissolution rates by factors of 13–24 and 14–24, respectively. In continuously stirred tank reactors (27 °C, pH 3.0), arsenic remained below 13 mg/l for NFC and reached 2.3 g/l for GFC. Dissolved iron was around 100 mg/l for NFC and below 5 mg/l for GFC. Bioleaching microorganisms enriched from the mine site included iron- and sulfur-oxidizing bacteria related to Acidithiobacillus ferrooxidans, Acidithiobacillus ferrivorans, Acidithiobacillus caldus and Thiomonas cuprina. These results show that nickel and cobalt can be recovered from NFC and GFC. Further, that dissolved arsenic can be controlled via biologically-mediated oxidation and subsequent precipitation of ferric iron.

Thermodynamics of dissolution of chromium(III) and cobalt(III) trisacetylacetonates in water-ethanol solvents

The study presents solubility data for chromium(III) and cobalt(III) trisacetylacetonates in water-ethanol solvents over a wide range of temperatures and ethanol concentrations. The solubilities of both compounds increase as the temperature or ethanol concentration is raised, particularly in the case of Cr(acac)3 it increases to a greater extent. Noteworthy, for ethanol concentrations of 1.4–1.6 mol/L tinversion of the temperature effect on the solubilities of both compounds is observed. For ethanol concentrations lower than 1.4–1.6 mol/L, dissolution of Cr(acac)3 and Co(acac)3 is exothermic, whereas for the higher concentrations, it is endothermic. The changes in enthalpy and entropy upon dissolution of the compounds under study were evaluated using the temperature dependence of solubility.

CO Impact on the Stability Properties of PtxCoy Nanoparticles in PEM Fuel Cell Anodes: Mechanistic Insights

Based on a multiscale modeling framework, we focus on understanding the impact of CO adsorption on the intrinsic stability properties of PtxCoy nanoparticles under PEMFC anode operating conditions. Firstly, CO adsorption effect on PtxCoy has been studied by using Monte Carlo (MC) simulation. Then, the MC results were coupled with a non-equilibrium thermodynamics kinetics model (MEMEPhys®) to simulate the effect of CO poisoning on the activity and durability of PtxCoy nanoparticles as HOR catalysts. The results are compared with simulations carried out on Pt, where potential self-oscillatory behaviour is observed and experimentally confirmed. The PtxCoy HOR activity and stability properties reveal to be strongly dependent on the nanoparticle size and composition. For certain nanoparticle sizes, simulations show that PtCo nanoparticles provide better CO tolerance than Pt3Co. However, the CO tolerance of PtCo degrades faster than that of Pt3Co in long-term operation. From both modeling and experimental approaches, it is demonstrated for the first time that this observation is due to the fact that CO adsorption enhances Cobalt dissolution.

Comparative leaching of spent zinc-manganese-carbon batteries using sulfur dioxide in ammoniacal and sulfuric acid solutions

The non-magnetic fraction of spent zinc-manganese-carbon batteries containing 20.8% Zn, 22.7% Mn, 2.65% Fe, and < 0.1% Hg, Ni, Co, Cu and Pb was leached in H 2SO 4, H 2SO 4/SO 2, NH 3 and NH 3/SO 2 at 30-60 °C. In acid media the complete dissolution of zinc is unaffected by SO 2. However, the reductive role of SO 2 increases the leaching of manganese in H 2SO 4 from 25% to 100% and iron from 1% to 25%. Literature results of leaching with other reductants are compared. The XRD analysis of leach residues from ammonia solutions shows the conversion of Zn 5(OH) 8Cl 2·H 2O in the feed to ZnO with low dissolution of zinc, manganese and iron. Low leaching of iron in NH 3/SO 2 is due to the formation of Fe(NH 4) 2(SO 3) 2 and Fe(NH 4) 2(SO 4) 2 identified by XRD analysis of leach residues. However, the formation of Zn(NH 3) 4 2+ facilitates the selective leaching of zinc in buffered SO 2/NH 3 solutions that contains NH 4 +. Complete dissolution of copper also occurs in both H 2SO 4/SO 2 and NH 3/SO 2. The dissolution of mercury by H 2SO 4 is retarded in the presence of SO 2, and enhanced by NH 3/SO 2. Lead remains insoluble in all media, whilst the partial dissolution of nickel and cobalt is retarded by NH 3/SO 2.

Dissolution of Cobalt from CoO/Al2O3 Catalyst with Mineral Acids

In this study, the dissolution of CoO from CoO/Al2O3 catalyst with HCl, H2SO4, and HNO3 solutions was investigated in a batch reactor employing parameters that were expected to affect the dissolution rate of cobalt, such as stirring speed, temperature, and acid concentration. It was found that 99.82% of cobalt was dissolved after 4 h with HCl at 2 M, 75 °C, and a liquid-to-solid ratio (l/s) of 100 mL/g, while only 31.96% and 13.57% cobalt dissolutions were reached with H2SO4 and HNO3, respectively, under the same operation conditions. The difference in dissolution rates was due to the presence of different anions (Cl−, NO3−, and HSO4−) involved in the surface reactions. Dissolution kinetic of cobalt was examined according to a heterogeneous model. It was found that the dissolution rate was controlled by surface chemical processes in all cases.

Dissolution of cobalt and zinc from natural and anthropogenic dusts in seawater

Abstract. Atmospheric dust inputs to the surface ocean are a major source of trace metals likely to be bio-available for phytoplankton after their dissolution in seawater. Among them, cobalt (Co) and zinc (Zn) are essential for phytoplankton growth and for the distribution of the major groups such as coccolithophorids, cyanobacteria and diatoms. The solubility in seawater of Co and Zn present in natural and anthropogenic dusts was studied using an open-flow reactor with and without light irradiation. Those dusts can be transported in the atmosphere by the wind before being deposited to the surface ocean. The analyses of cobalt and zinc were conducted using voltammetric methods and the global elemental composition of dust was determined by ICP-AES. This study highlighted the role of the dust origin in revealing the solubility characteristics. Much higher dust solubility was found for zinc as compared to cobalt; cobalt in anthropogenic particles was much more soluble (0.78%) in seawater after 2 h of dissolution than Co in natural particles (0.14%). Zinc showed opposite solubility, higher in natural particles (16%) than in anthropogenic particles (5.2%). A natural dust event to the surface ocean could account for up to 5% of the cobalt inventory and up to 50% of the Zn inventory in the mixed layer in the Pacific Ocean whereas the cobalt and zinc inventories in the mixed layer of the Atlantic Ocean might already include the effects of natural dust inputs and the subsequent metal dissolution. Anthropogenic sources to the surface ocean could be as important as the natural sources, but a better estimate of the flux of anthropogenic aerosol to the surface ocean is needed to further estimate the anthropogenic inputs. Variations in natural and anthropogenic inputs may induce large shifts in the Co/Zn ratio in the surface ocean; hence it could impact the phytoplankton community structure.

Siderophore-promoted dissolution of cobalt from hydroxide minerals

Recent research has revealed that siderophores, a class of biogenic ligands with high affinities for Fe(III), can also strongly complex Co(III), an element essential to the normal metabolic function of microbes and animals. This study was conducted to quantify the rates and identify the products and mechanisms of the siderophore-promoted dissolution of Co from synthetic Co-bearing minerals. The dissolution reactions of heterogenite (CoOOH) and four Co-substituted goethites (Co-FeOOH) containing different Co concentrations were investigated in the presence of a trihydroxamate siderophore, desferrioxamine B (DFOB), using batch and flow-through experiments. Results showed that DFOB-promoted dissolution of Co from Co-bearing minerals may occur via pH-dependent ligand-promoted or reductive dissolution mechanisms. For heterogenite, ligand-promoted dissolution was the dominant pathway at neutral to alkaline pH, while production of dissolved Co(II) for pH <6. It was not possible from our data to decouple the separate contributions of homogenous and heterogeneous reduction reactions to the aqueous Co(II) pool. Cobalt substitution in Co-substituted goethite, possibly caused by distortion of goethite structure and increased lattice strain, resulted in enhanced total dissolution rates of both Co and Fe. The DFOB-promoted dissolution rates of Co-bearing minerals, coupled with the high affinity of Co(III) for DFOB, suggest that siderophores may be effective for increasing Co solubility, and thus possibly Co bioavailability. The results also suggest that siderophores may contribute to the mobilization of radioactive 60Co from Co-bearing mineral phases through mineral weathering and dissolution processes.

Dissolution of cemented carbide powders in artificial sweat: implications for cobalt sensitization and contact dermatitis

Skin exposure to cobalt-containing materials can cause systemic immune sensitization and upon repeat contact, elicitation of allergic contact dermatitis (ACD). Data on cobalt dissolution rates are needed to calculate uptake through skin and for development of models to understand risk of sensitization or dermatitis. The purpose of this research was to measure the dissolution kinetics of feedstock and process-sampled powders encountered in the production of hard metal alloys using artificial sweat. The physicochemical properties of each material were characterized prior to evaluation of dissolution behavior. Variations in artificial sweat solvent pH and chemistry were used to understand critical factors in dissolution. Dissolution of cobalt, tungsten, and tungsten carbide was often biphasic with the initial rapid phase being up to three orders of magnitude faster than the latter long-term phase. Artificial sweat pH did not influence dissolution of cobalt or tungsten carbide. Solvent composition had little influence on observed dissolution rates; however, vitamin E suppressed the dissolution of cobalt and tungsten carbide from sintered particles obtained from a chamfer grinder. There was no effect of particle size on dissolution of feedstock cobalt, tungsten, tungsten carbide, and admixture powders. Particle physicochemical properties influenced observed dissolution rates with more cobalt and tungsten carbide dissolving from chamfer grinder particles compared to the feedstock powders or admixture powder. Calculations using the observed dissolution rates revealed that skin exposure concentrations were similar to concentrations known to induce cobalt sensitization and elicit ACD. Observed dissolution rates for cobalt in artificial sweat indicate that dermal uptake may be sufficient to induce cobalt sensitization and allergic dermatitis.

黄鉄鉱とのガルバニック反応によるコバルト・リッチ・クラストの浸出について

Cobalt-rich ferromanganese crusts (cobalt crust) contain strategic metals such as copper, nickel and cobalt. In order to recover cobalt, the reduction and dissolution of manganese oxide in crusts is required because cobalt is interlocked in manganese oxide. It is known that galvanic interactions between metal sulfide minerals and manganese nodule cause oxidation-reduction reactions on them. In this study, galvanic leaching of chemical analytical MnO2 and cobalt crust has been examined in the presence of pyrite.The measurement of rest potential indicated that MnO2 was nobler than pyrite. The dissolution of the MnO2 was accelerated in the presence of pyrite because MnO2 could act as cathode to be reduced in the galvanic couple MnO2/FeS2 .The dissolution of manganese and cobalt from the cobalt crust was enhanced in the presence of pyrite, and 84% of cobalt was extracted in three days while about 1% in the absence of pyrite in sulfuric acid solution of pH0.8. The leaching of the cobalt crust has been studied under various experimental parameters such as pH, amount of pyrite and particle size.

Improved Electrochemical Performance of NH[sub 4]AlF[sub 4]-Coated LiCoO[sub 2] Cycled over 4.5 V

Cathode coatings are being developed to improve lithium-ion batteries. In this effort, particles were coated with by a simple dry-coating process to enhance capacity retention on a 4.5 V cutoff cycling. Compared with pristine , this coating greatly improved the electrode cyclability and rate capability. Electrochemical impedance spectroscopy and a cobalt dissolution test showed that the coating protected the particle surface from HF and, thus, suppressed the increase in interfacial impedance between the cathode and electrolyte that occurred with an uncoated cathode material.

Electrochemical recovery of cobalt and copper from spent Li-ion batteries as multilayer deposits

In this work, spent Li-ion batteries were used to form cobalt and copper multilayers by electrodeposition. The effects of pH on the nucleation and growth mechanism, morphology and crystalline structure were studied. The instantaneous nucleation mechanism occurs at pH 2.7 and progresses at pH 5.4 for cobalt electrodeposition on platinum, vitreous carbon and aluminum. Copper can be electrodeposited on cobalt by an instantaneous mechanism at pH 2.7 and progressively at pH 5.4. Using scanning electron microscopy, we verified a more porous electrodeposit at pH 5.4 than at pH 2.7. X-ray diffractograms showed the peaks of Cu 2O, CuO and the Co and Cu cubic centered face structures for both pH values at a charge density of 2.00 and 10.0 C cm −2. The electric circuit obtained by electrochemical impedance spectroscopy for Co–Cu multilayer growth at both pH 2.7 and 5.4 with a charge density equal to 2.0 and 10.0 C cm −2 on Al has the form R s( R p QL). The presence of the constant phase element ( Q) is attributed to the irregularity of the Co–Cu multilayer electrodeposits, and the inductive element ( L) is associated with cobalt dissolution in acidic solution.

Possible Explanation for the Efficiency of Al-Based Coatings on LiCoO2: Surface Properties of LiCo1−xAlxO2 Solid Solution

Aluminum-based coatings are commonly used in lithium-ion batteries to modify the surface of LiCoO2 particles, to limit cobalt dissolution in the electrolyte at high voltage. It was shown that the formation of a LiCo1−xAlxO2 solid solution occurs at the interface between the coating and the core material. In this paper, we investigated the surface properties of LiCo1−xAlxO2 materials by X-ray photoelectron spectroscopy. We explored the surface acid−base properties of these materials by adsorption of gaseous probe molecules (NH3 and SO2) followed by XPS analyses. We showed that the basic character of the LiCo1−xAlxO2 surface strongly decreases when x increases, which makes these materials less reactive than LiCoO2 toward acidic species (such as HF) that are present in LiPF6-based electrolytes. This is a possible explanation for the efficiency of Al-based coatings to protect LiCoO2 against cobalt dissolution in the electrolyte.

Behaviour of cobalt during sulphuric acid pressure leaching of a limonitic laterite

Extraction of nickel and cobalt from lateritic ores by sulphuric acid pressure leaching techniques has become increasingly important in recent years. The above hydrometallurgical method has a low operational cost and is environmentally safe compared to the energy-intensive and air-polluting pyrometallurgical processes. High nickel and cobalt recovery of more than 90%, with a high selectivity due to the simultaneous iron and aluminium dissolution and precipitation, can be achieved. Experiments were carried out using batch pressure leaching techniques. A titanium autoclave equipped with acid injection and sample withdrawal units was employed. Conditions close to the industrial practice were tested; pulp density: 10–30%, acid to ore ratio: 0.15–0.35 and temperature ranging from 230 to 270 °C. Raw limonitic laterite and the evolution of the nature of solid products during leaching were thoroughly investigated using Transmission Electron Microscopy (TEM). Whereas nickel is predominately associated with the goethite phase, cobalt was found to exist only in nickel-rich manganese structures. During leaching, goethite dissolves liberating nickel while iron re-precipitates as dense hematite particles in solution by ex situ precipitation. Cobalt dissolves rapidly and remains in the aqueous phase. Manganese follows the cobalt dissolution pattern, however at a much lower rate. In the end of the leaching tests, manganese particles get almost depleted of cobalt. The dissolution rate of cobalt during leaching was insensitive to the increase of temperature in the above tested range. However, increasing the agitation rate of the slurry led to the increase of its dissolution rate. The above findings, along with the TEM photos and the respective mineralogical analysis, indicate that film diffusion is most possibly the rate-controlling step. The shrinking core model could be employed in order to describe cobalt dissolution kinetics.

Electrochemical behavior of copper and cobalt in post-etch cleaning solutions

Cleaning is one of the key steps of the integration of self aligned barriers (SAB) in microelectronic devices for 32 nm technology and below. It is hence important to investigate the impact of different cleaning solutions on the metallic components of SAB, mainly in which concerns their surface stability. In this sense, the electrochemical behavior of copper and cobalt was studied under potentiodynamic conditions in different aqueous solutions of glycolic acid (GA) with and without benzotriazole (BTA) inhibitor. It has been observed that the presence of glycolic acid induces a monotonic increase of copper corrosion and a slight decrease in the case of cobalt. The cobalt dissolution remains nonetheless very active and is shown to be governed by oxygen reduction reaction. The addition of BTA, a well-known corrosion inhibitor for copper has shown to be also effective in the case of Co surfaces, with a ca 15-fold reduction of the intrinsic Co corrosion current density. The possibility of galvanic coupling between both metals, supposed to enhance the Co dissolution, has also been qualitatively investigated and seems not to be a determinant factor in these conditions.