A Study on Removal of Rare Earth Elements from U.S. Coal Byproducts by Ion Exchange

Rozelle, Peter L.; Khadilkar, Aditi B.; Pulati, Nuerxida; Soundarrajan, Nari; Klima, Mark S.; Mosser, Morgan M.; Miller, Charles E.; Pisupati, Sarma V.

doi:10.1007/s40553-015-0064-7

Cited by 42 publications

(40 citation statements)

References 21 publications

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“…In fact, bauxite residue could become a major source of scandium [116]. The ionic liquid [BMIM]Cl and the deep-eutectic solvent choline chloride:urea (1:2 molar ratio) were used for the recovery of REEs from coal byproducts using ion exchange, but the ionic liquid and the deep-eutectic solvent did not show any advantages over leaching with an aqueous ammonium sulfate solution [120].…”

Section: Ionometallurgical Processesmentioning

confidence: 99%

Solvometallurgy: An Emerging Branch of Extractive Metallurgy

Binnemans

Jones

2017

J. Sustain. Metall.

234

187

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This position paper introduces the reader to the concept of solvometallurgy, the term used to describe the extraction of metals from ores, industrial process residues, production scrap, and urban waste using non-aqueous solutions. Here, non-aqueous is not used to imply anhydrous, but rather a low water content. The unit operations are as follows: solvent leaching; separation of the residue; purification of the leach solution by non-aqueous solvent extraction or non-aqueous ion exchange; and metal recovery by precipitation or electrolysis in non-aqueous electrolytes. Solvometallurgy is similar to hydrometallurgy in that both the branches of extractive metallurgy use lowtemperature processes, but with solvometallurgy, there is no discrete water phase. Both branches use organic or inorganic solvents (excluding water in the case of solvometallurgy). However, for solvometallurgical processes to be sustainable, they must be based on green solvents, which means that all toxic or environmentally harmful solvents must be avoided. Solvometallurgy is complementary to pyrometallurgy and hydrometallurgy, but this new approach offers several advantages. First, the consumption of water is very limited, and so the generation of wastewater can be avoided. Second, the leaching and solvent extraction can be combined to form a single step, resulting in more simplified process flow sheets. Third, solvent leaching is often more selective than leaching with acidic aqueous solutions, leading to reduced acid consumption and fewer purification steps. Fourth, solvometallurgy is useful for the treatment of ores rich in soluble silica (e.g., eudialyte) because no silica gel is formed. In short, solvometallurgy is in a position to help develop the near-zero-waste metallurgical processes, and with levels of energy consumption that are much lower than those with the high-temperature processes. The Technology Readiness Level (TRL) of this emerging branch of extractive metallurgy is still low (TRL = 3-4), which is a disadvantage for short-term implementation, but offers a great opportunity for further research, development, and innovation.

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Section: Ionometallurgical Processesmentioning

confidence: 99%

Solvometallurgy: An Emerging Branch of Extractive Metallurgy

Binnemans

Jones

2017

J. Sustain. Metall.

234

187

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“…Based on this datum, Zhang et al [6] further estimated the cut-off grade of REE in coal which is 115-130 ppm on the whole coal basis and 677-762 ppm on the ash basis. An analysis of the U.S. Coal Quality Database showed that greater than 700 ppm (ash basis) REE are distributed in the U.S. coal basins [6].A study by Rozelle et al [12] suggested that U.S. coal byproducts may be technically suitable as REE ores.Therefore, coal and coal by-products are promising alternative sources for REE recovery.Advantages of utilizing coal and coal byproducts as feedstocks for REE production include: (1) large and reliable sources, (2) already mined materials (no need for new mining permits), (3) potential environmental and health benefits from no new mining, and (4) utilizing potential waste materials. The recovery of REE from coal and coal by-products is promising also because of current limitations with developing new conventional metalliferous mines, the decreasing reserves of RE metals in conventional deposits, and growing application of these valuable metals in modern technology [13].Development of processes and technologies for the economic recovery of REE from coal and coal by-products would be game-changing and beneficial, particularly to countries like the U.S. that rely heavily on REE imports.…”

Section: Introductionmentioning

confidence: 99%

Enrichment of rare earth elements from coal and coal by-products by physical separations

Lin

Howard

Roth

et al. 2017

Fuel

159

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Rare earth elements (REE) are of strategic importance because they find numerous applications in various sectors of the global economy.The concern about the REE supply challenge has led to increasing interest and research in the recovery of REE from end-of-life products and secondary sources such as coal and coal by-products. The work reported here was focused on examining the technical feasibility of physical separation techniques for the enrichment of REE from coal and coal by-products. Particle size, magnetic and density separations were performed on coal, coal ash, clay and shale samples. It was found that the samples responded to particle size separation differently. For all ash samples, higher REE concentrations were found in the finer fractions. For the clay and shalesamples, however, the REE concentrations decrease as the particle size reduces possibly because RE minerals were not effectively released by grinding. Magnetic separation showed that REE are enriched in non-magnetic fractions for all ash samples. All samples responded similarly to density separation. Among the three methods, density separation showed the highest enrichment of REE. A combination of these methods is recommended. Finally, correlations between elements were demonstrated, which leads to the classification of three groups containing mainly Al/Si, Fe and Ca, respectively. REE are strongly associated with the Al/Si group.

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“…The abundance of neodymium-iron-boron magnets (NdFeB) in cell phones, hard drives and wind turbines forms the major target for this recycling effort with promising results on Nd recovery in the laboratory (Vander Hoogerstraete et al, 2014). In addition, development of REY production from industrial waste or by-products such as red-mud (Ochsenkühn-Petropulu et al, 1996, Tsakanika et al, 2004, Qu and Lian, 2013, Liu and Naidu, 2014, Borra et al, 2015 and coal residue (Rozelle et al, 2016a) has received considerable interest. These formations contain REY-bearing minerals and/or adsorbed REY that are transferred to the wastes during initial ore processing.…”

Section: Solvent Extraction Constitutes the Most Common Treatment Of mentioning

confidence: 99%

Extraction and separation of rare earth elements from hydrothermal metalliferous sediments

Josso

Roberts

Teagle

et al. 2018

Minerals Engineering

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Rare earth elements (REE) can be efficiently extracted from umbers, ferromanganese metalliferous sediments of the Troodos ophiolite (Cyprus) by simple leaching and selective precipitation, without accumulation of radioactive by-products. Umbers are dominantly composed of amorphous Fe and Mn oxides with minor goethite, quartz and zeolites, and contain 350-500 mg.kg-1 of rare earth elements and yttrium (REY), 200 times lower than many of the major REY source ores. To compensate for relatively low grades, a cost-effective extraction process was developed that utilises a weak lixiviant concentration (0.1-1.5 N) and short reaction times (5 min to 11 h). Acid solutions recover 70-85% of the initial sample REY content even at 20 °C. By contrast, extraction using ionic solutions of NaCl and ammonium sulphate proved ineffective. Acid recoveries of REY increase by nearly 10% at 70 °C and the use of different acids (HCl, HNO3, H2SO4) yields comparable results. The main impurities in the leachate include Ca and Na at even the weakest acid concentration (0.1 N). However, two-step leaching method greatly reduces concentrations of impurities in the REY-rich liquor, although with REY losses approaching 20%. Purification of the leach liquor via selective precipitation of REY as an oxalate is highly efficient although pH dependent. With maximum REY precipitation (96-99%) occurring between pH 1 and 2, the precise adjustment of pH allows separation of REY from other precipitating impurities (Ca). The maximum purity of the precipitate is achieved at pH 1.1 (> 65%). Strong and consistent fractionation along the lanthanide series observed during the precipitation experiments has been successfully explained using a speciation modelling software (PHREEQC). The uptake of REY by oxalate in the experiments closely follows the bell-shape distribution of REY-oxalate solid complexes stability constant (-log β (RE2Ox3.nH2O)) replicating the fractionation trends observed at pH < 1.1. In addition, the modelling demonstrates that at equivalent REE concentration in solution, oxalate precipitates fractionate REY in the following order: middle REE > light REE >> heavy REE. This ordering and the variable degrees of uptake reflects the interplay of aqueous REY-oxalate complexes (log HOxβ1, Oxβ1 and Oxβ2) with the natural fractionation induced by solid REY-oxalate stability constant distribution. Overall, the combined leaching process and selective oxalate precipitation produces a total enrichment factor ranging between 1400 and 2400 for REY from the sample to the oxalate precipitate in a simple twostep process forming a high-purity end-product of mixed REY.

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A Study on Removal of Rare Earth Elements from U.S. Coal Byproducts by Ion Exchange

Cited by 42 publications

References 21 publications

Solvometallurgy: An Emerging Branch of Extractive Metallurgy

Solvometallurgy: An Emerging Branch of Extractive Metallurgy

Enrichment of rare earth elements from coal and coal by-products by physical separations

Extraction and separation of rare earth elements from hydrothermal metalliferous sediments

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