Production of rare earth and thorium compounds from monazite. Part I

Pilkington, E. S.; Wylie, A. W.

doi:10.1002/jctb.5000661103

Cited by 30 publications

(6 citation statements)

References 8 publications

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“…The dissolution of thorium was consistently low in acid bake/leach tests using leach solutions of pH 1 and a liquid to solid ratio of 20:1, even for bake temperatures of 200-300°C where information from the literature predicted high dissolutions of thorium (Eyring, 1964;Pilkington and Wylie, 1947;Takeuchi, 1976). Analysis of the 300°C bake/leach residue by XRF showed that the residue was highly enriched in thorium.…”

Section: Effect Of Leach Aciditymentioning

confidence: 98%

“…Sulfuric acid based treatment of monazite has a long history, being first developed in the early-mid 1900's for the recovery of rare earths and thorium from high grade beach sand monazites (Kithil, 1915;Pilkington and Wylie, 1947;Shaw et al, 1954). Early processes involved digestion of monazite in stirred reactors at 200-245°C, using an acid:concentrate weight ratio varying from 1.5:1 to 3:1 (Borrowman and Rosenbaum, 1961;Pilkington and Wylie, 1947;Shaw et al, 1954). Shaw et al (1954) found that a minimum temperature of about 200°C was required for near complete monazite decomposition, while the minimum acid:concentrate ratio required was 1.6:1 for the two samples tested.…”

Section: Accepted Manuscript 1 Introductionmentioning

confidence: 99%

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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

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: Effect Of Leach Aciditymentioning

confidence: 98%

Section: Accepted Manuscript 1 Introductionmentioning

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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“…Figure 7 Effect of H 2 SO 4 concentration on the solubility of Ce 2 (SO 4 ) 3. Data from Linke and Seidell (1965) For high grade concentrates of both monazite and bastnasite a water to solid ratio of 10:1 has been widely used (see (Pilkington and Wylie, 1947;Shaw, 1959a).…”

Section: Liquid To Solid Ratiomentioning

confidence: 99%

“…Figure 8 shows the effect of temperature on solubility of lanthanum sulfate and thorium sulfate. Because of the inverse relationship of solubility with temperature for the rare earth sulfates, water leaching is generally carried out at ambient or colder temperatures to maximise rare earth solubility (Pilkington and Wylie, 1947). The effect of increasing temperature was investigated by Kul et al (2008) during water leaching of Beylikahır bastnasite preconcentrate.…”

Section: Temperaturementioning

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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“…Recovery of Rare Earths. After extraction of thorium and uranium, rare earths are readily recovered from the liquor by salting out the sodium double sulfate with sodium chloride or sodium sulfate (73,19). The precipitate settles and filters extremely rapidly.…”

Section: Recovery From Monazitementioning

confidence: 99%

The Amex Process for Extracting Thorium Ores with Alkyl Amines

Crouse¹,

Brown²

1959

Ind. Eng. Chem.

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Production of rare earth and thorium compounds from monazite. Part I

Cited by 30 publications

References 8 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

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

The Amex Process for Extracting Thorium Ores with Alkyl Amines

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Production of rare earth and thorium compounds from monazite. Part I

Cited by 30 publications

References 8 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

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

The Amex Process for Extracting Thorium Ores with Alkyl Amines

Contact Info

Product

Resources

About

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