Rare earth metal ion solubility in sulphate-phosphate solutions of pH range −0.5 to 5.0 relevant to processing fluorapatite rich concentrates: Effect of calcium, aluminium, iron and sodium ions and temperature up to 80°C

Senanayake, Gamini; Jayasekera, S.; Bandara, Ajith; Koenigsberger, E.; Koenigsberger, L.; Kyle, J.

doi:10.1016/j.mineng.2016.07.022

Cited by 30 publications

(11 citation statements)

References 14 publications

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“…For the second stage, the sample was heated at 5°C/min to the final target temperature and held for two hours. Baked samples were cooled and ground to a fine powder before leaching at a liquid to solid ratio of 40:1 in 0.9 M sulfuric acid at 20-25°C for 2 h. The solubility of sulfate salts of rare earth metal ions is highest at sulfuric acid concentrations closer to 1 M at ambient temperatures (Senanayake et al, 2016). Solid-liquid separation after leaching was by vacuum filtration.…”

Section: Accepted Manuscript 2 Materials and Methodsmentioning

confidence: 99%

Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C

Demol

Senanayake

2018

Hydrometallurgy

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Monazite, a rare earth and thorium bearing phosphate mineral, is one of the major minerals used for the production of rare earth elements. Although sulfuric acid baking is one of the main processing routes for extraction of rare earth elements from monazite, the chemistry involved is not well understood. In this study, a combination of chemical analysis and standard characterisation techniques (XRD, SEM-EDS, FT-IR and TG-DSC) was used to identify reaction processes occurring during the sulfuric acid baking of monazite between 200 and 800°C. The effects of these reactions on the leachability of the rare earths, thorium and phosphate were also examined. It was observed that the sulfation reaction of monazite with acid was virtually complete after baking at 250°C for 2 h, resulting in >90% solubilisation of rare earth elements, thorium and phosphate. After baking at 300°C, a thorium phosphate type precipitate was formed during leaching, leading to a sharp decrease in extraction of thorium and phosphate, but the leaching of rare earth elements reached nearly 100%. The EDS and FT-IR analyses of this precipitate were indicative of a thorium pyrophosphate. As the bake temperature was further increased to 400-500°C, extraction of thorium, phosphorus and the rare earth elements decreased due to formation of insoluble thorium-rare earth polyphosphates. The formation of these polyphosphates is thought to be related to dehydration of orthophosphoric acid produced in the initial reaction of monazite with sulfuric acid. Between 650 and 800°C, monazite was partially re-formed, leading to a further decrease in rare earth extraction to 55%. The re-forming of monazite appeared to be due to a reaction between the thorium-rare earth polyphosphates and rare earth sulfates.

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Section: Accepted Manuscript 2 Materials and Methodsmentioning

confidence: 99%

Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C

Demol

Senanayake

2018

Hydrometallurgy

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“…This is probably due to the higher stability of REE-sodium-sulphate double salts than that of REE-Cit complexes in the solution with a high sodium sulphate concentration. 33 Therefore, the constant citrate concentration in this study does not influence the REE recovery in a long run. Correspondingly, with the initial electrolyte bath of 0.6 mol L −1 FeSO 4 + 0.4 mol L −1 (NH 4 ) 2 SO 4 + 0.175 mol L −1 Na 3 Cit + 0.4 mol L −1 H 3 BO 3 , the current efficiency of the Fe deposition was kept within 70.9-75.7% (indicated with pink-dashed lines in Fig.…”

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confidence: 76%

A facile method for the simultaneous recovery of rare-earth elements and transition metals from Nd–Fe–B magnets

Šturm

Samardžija

et al. 2020

Green Chem.

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“…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%

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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Rare earth metal ion solubility in sulphate-phosphate solutions of pH range −0.5 to 5.0 relevant to processing fluorapatite rich concentrates: Effect of calcium, aluminium, iron and sodium ions and temperature up to 80°C

Cited by 30 publications

References 14 publications

Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C

Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C

A facile method for the simultaneous recovery of rare-earth elements and transition metals from Nd–Fe–B magnets

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

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Rare earth metal ion solubility in sulphate-phosphate solutions of pH range −0.5 to 5.0 relevant to processing fluorapatite rich concentrates: Effect of calcium, aluminium, iron and sodium ions and temperature up to 80°C

Cited by 30 publications

References 14 publications

Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C

Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C

A facile method for the simultaneous recovery of rare-earth elements and transition metals from Nd–Fe–B magnets

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

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Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C

Sulfuric acid baking and leaching of rare earth elements, thorium and phosphate from a monazite concentrate: Effect of bake temperature from 200 to 800 °C