Control of autoclave scaling during acid pressure leaching of nickeliferous laterite ore

Queneau, Paul B.; Doane, R. E.; Cooperrider, M. W.; Berggren, Mark; Rey, P.

doi:10.1007/bf02657373

Cited by 32 publications

(20 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Scale represents a significant industrial problem for HiPAL plants (Whittington and Muir 2000). For example, a five-to seven-day monthly shutdown for descaling purposes was required at the Moa Bay operation, Cuba (Queneau et al 1984). Previous investigations of HiPAL scale have focused on the effects of pressure, temperature, pH, and additives on the mineral chemistry, phase stability, and deposition rate of HiPAL scale (Johnson et al 2005;Papangelakis et al 1994;Scarlett et al 2008;Whittington 2000;Whittington et al 2003aWhittington et al , 2003b.…”

Section: High-pressure Acid Leaching Of Nickel Lateritesmentioning

confidence: 97%

Quantitative microstructural characterization of natrojarosite scale formed during high-pressure acid leaching of lateritic nickel ore

Timms

Reddy

2009

American Mineralogist

View full text Add to dashboard Cite

The build up of scale inside autoclaves during high-pressure acid leaching of nickel laterite ore currently represents a significant industrial problem in processing plants. In this study, the crystallographic microstructure of natrojarosite scale developed on stirring rods inside a high-pressure acid leach autoclave are investigated using electron backscatter diffraction (EBSD). Backscatter electron imaging shows compositional layering of natrojarosite with dispersed minor iron oxide crystals and regularly spaced, parallel layer micro-porosity. Analysis of the scale by EBSD reveals that natrojarosite forms elongate grains with strong (0001) crystallographic preferred orientation with c axes aligned within the plane of the agitator substrate, consistent with unitaxial precipitation from a fluid. The natrojarosite grains contain a complex internal substructure of low-angle (<15°) boundaries that define elongate subgrains and accommodate up to 40° of systematic misorientation across single grains. Low-angle subgrain boundaries do not have simple twin relationships or low-index misorientation axes and are interpreted to have formed as a result of the propagation of crystal defects during growth rather than by syn-growth deformation due to shear stresses between viscous leachate slurry and the agitator inside the autoclave. The presence of extended defects in the scale microstructure has implications for the solubility and reactive stability of mineral processing waste as well as for the development of scale growth inhibitors.

show abstract

Section: High-pressure Acid Leaching Of Nickel Lateritesmentioning

confidence: 97%

Quantitative microstructural characterization of natrojarosite scale formed during high-pressure acid leaching of lateritic nickel ore

Timms

Reddy

2009

American Mineralogist

View full text Add to dashboard Cite

show abstract

“…These results confirm that at the potential corresponding to the anodic dissolution of iron, a CoS x species deposits onto the iron surface, as proven by the presence of peak E, resulting from its oxidation. Two possible mechanisms have been suggested in the past for the reduction of thiosulfate ions during the first leaching stage of the Caron process (Queneau and Weir, 1986). One is the reduction to sulphide by metallic iron as it is dissolved oxidatively to form a ferrous ammine.…”

Section: Study Of the Cos X Layer Formed On Ironmentioning

confidence: 99%

An electrochemical investigation of the formation of CoSx and its effect on the anodic dissolution of iron in ammoniacal-carbonate solutions

D'Aloya

Nikoloski

2013

Hydrometallurgy

View full text Add to dashboard Cite

ÔØ Å ÒÙ× Ö ÔØThis is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractIt has been found that the co-presence of cobalt (II) and thiosulfate ions in ammoniacal-carbonate solutions promotes the passivation of iron, under conditions in which it would otherwise continue to dissolve anodically. Electrochemical experiments have shown a relationship between the immersion time required for passivation and the formation of a solid species on the iron surface, which is thought to be implicated in the mechanism of passivation, whilst not being itself the protective species. Based on a combination of electrochemical, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and grazing incidence X-ray diffraction (GIXRD) characterisation techniques, said species has been identified as CoS x , resulting from the interaction of cobalt (II) and thiosulfate ions. It is thought to form as a product of the cathodic reactions taking place on the iron surface during its active dissolution.These findings are particularly relevant to the Caron process, in which ammoniacal-carbonate solutions containing dissolved cobalt and thiosulfate ions are used to leach nickel and cobalt from pre-reduced laterite ores rich in metallic iron. Both the loss of cobalt into the CoS x layer and the passivation of iron and of its alloys with nickel and cobalt, are potential contributing factors to the low cobalt and nickel recoveries, which are typical of the Caron process. This study provides a better understanding of the conditions under which the CoS x layer forms and promotes the passivation of iron, and may therefore provide useful information to help minimise the effect this may have on the extraction efficiency of the process. In particular, at the cobalt and thiosulfate ion concentrations usually encountered at a Caron plant, the passivation of iron was found to be prevented by maintaining a high enough concentration of ammonia.

show abstract

“…One of the operating problems that must be addressed in design of pressure leaching systems is scaling of reactor surfaces [27]. The economic feasibility of the HPAL route for the extraction of nickel and cobalt values from silicate ores is highly dependent upon the behavior of aqueous aluminum.…”

Section: State-of-the-art Pressure Hydrometallurgymentioning

confidence: 99%

Pressure hydrometallurgy: A new chance to non-polluting processes

Stopić¹,

Friedrich²

2011

Vojnotehnički glasnik

View full text Add to dashboard Cite

Abstract:A wide spectrum of hydrometallurgical processes offers many promising approaches for industrial application in order to improve the environmental impact of conventional metals productions, or for replacing pyrometallurgical processes whose gas emissions and a high content of formed metals (As, Cr, Pb) (gold, zinc, molybdenium, titanium, germanium) from ore deposits and secondary materials. High pressure leaching in combination with other metallurgical operations (cementation, precipitation, solvent extraction, and electrowinning) provides an adequate technology to reintroduce lost metals into the industrial cycle, thereby saving resources and energy, while keeping the environment cleaner. It seems that pressure hydrometallurgy might be a very important key to better and nonpolluting processes in production of metals.

show abstract

Control of autoclave scaling during acid pressure leaching of nickeliferous laterite ore

Cited by 32 publications

References 2 publications

Quantitative microstructural characterization of natrojarosite scale formed during high-pressure acid leaching of lateritic nickel ore

Quantitative microstructural characterization of natrojarosite scale formed during high-pressure acid leaching of lateritic nickel ore

An electrochemical investigation of the formation of CoSx and its effect on the anodic dissolution of iron in ammoniacal-carbonate solutions

Pressure hydrometallurgy: A new chance to non-polluting processes

Contact Info

Product

Resources

About