Solubility of Rare Earth Salts in Sulphate-Phosphate Solutions of Hydrometallurgical Relevance

Bandara, Ajith; Senanayake, Gamini; Perera, D. I.; Jayasekera, S.

doi:10.1007/978-3-319-95022-8_135

Cited by 1 publication

(4 citation statements)

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“…(Figure 6a) and facilitates the formation of Ce 2 (SO 4 ) 3 .8H 2 O (Figure 6b). Formation of hydrated rare-earth sulfate salts during baking of monazite concentrates and saturation of leach liquors have been confirmed by XRD scans (Bandara et al, 2018;Demol et al, 2018).…”

Section: Accepted Manuscriptmentioning

confidence: 81%

“…The Eh-pH diagrams for the system Th-RE-(PO 4 )-(SO 4 )-H 2 O at 25°C and different concentrations of metal ions (10 -3 , 10 -1 mol/L), phosphate (10 -3 mol/L) and sulfate (10 -2 , 10 -1 and 1 mol/L) published by Kim and Osseo-Asare (2012) predict the stability regions for a variety of species relevant to the hydrometallurgical processing of monazite via sulfuric acid baking and leaching. The solution composition and measured solubility of rare earths, thorium and uranium in sulfuric-phosphoric solutions produced after acid baking/leaching or pre-leaching of rare-earth concentrates provide useful information on solid phases and complex species of these metal ions relevant to baking, leaching and precipitation (Bandara and Senanayake, 2015;Bandara and Senanayake, 2019;Bandara et al, 2018;Demol et al, 2018;Senanayake et al, 2016;Stone et al, 2016).…”

Section: Type Of Saltmentioning

confidence: 99%

“…Solubility products (pK sp ) are in the range of 2.0-2.5 for Y 2 (SO 4 ) 3 and Nd 2 (SO 4 ) 3 , respectively (Table 15). The effective rare earth solubility in a sulfate based leach solution is highly dependent on the speciation of the complexes formed in solution and the solids precipitated upon saturation, and their solubility (Bandara et al, 2018;Senanayake et al, 2016). Figure 7 shows the detrimental effect of the increase of sulfuric acid concentration on the solubility of Ce 2 (SO 4 ) 3 , based on solubility values from Linke and Seidell (1965).…”

Section: Liquid To Solid Ratiomentioning

confidence: 99%

“…For concentrates with a significant proportion of soluble silicate minerals, sufficient dilution is necessary to prevent solidification or 'gelling' of the solution through silica polymerisation (Shaw et al, 1954). Whilst the formation of various sulfate/phosphate complex species of rare earth metal ions with sulfate/phosphate ions can enhance the solubility, the presence of other cations in solution originating from the feed/host minerals (Table 2) or additives used in baking/leaching can significantly affect the solubility of REEs due to the formation of other salts of variable solubility depending upon the pH, acid concentration and temperature (Senanayake et al, 2016;Bandara et al, 2018).…”

Section: Liquid To Solid Ratiomentioning

confidence: 99%

See 3 more Smart Citations

The sulfuric acid bake and leach route for processing of rare earth ores and concentrates: A review

Demol

Soldenhoff

et al. 2019

Hydrometallurgy

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Rare earths are critical to numerous materials and applications underpinning modern civilisation. The majority of the world's rare earth reserves are hosted in the three minerals bastnasite, monazite and xenotime. A key step in the processing of rare earth mineral concentrates is the chemical decomposition of the mineral structure to release the constituent elements. The sulfuric acid bake has historically been, and is also currently, one of the major processes used for this step. Current sulfuric acid bake processes for the Bayan Obo deposit in China and the Mt. Weld deposit in Australia together account for more than half of the world's rare earth production. In the sulfuric acid bake, the rare earth elements are converted to rare earth sulfates which are dissolved in a subsequent water leach. The conditions required to achieve mineral decomposition vary widely for different rare earth minerals.Adjustment of process conditions may often be used to achieve some degree of impurity rejection which is beneficial to downstream processing. This paper reviews the application of the sulfuric acid bake process to ores/concentrates containing mainly monazite, xenotime and bastnasite, and other less common rare earth minerals including euxenite, samarskite, fergusonite, loparite, allanite, eudialyte and pyrochlore. The reported effects of feed mineralogy and process variables such as reaction temperature, bake duration, acid to concentrate ratio and particle size are presented along with a brief review of current understanding of the bake chemistry and water leach results.

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Section: Accepted Manuscriptmentioning

confidence: 81%