Techno-economic analysis of supercritical extraction of rare earth elements from coal ash

Das, Saptarshi; Gaustad, Gabrielle; Sekar, Ashok; Williams, Eric

doi:10.1016/j.jclepro.2018.03.252

Cited by 87 publications

(27 citation statements)

References 37 publications

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“…Many studies have been published in recent years focused on the chemical extraction of REEs from coal combustion ashes [26,53,76,88,89,[91][92][93][94][95][96][97][98][99][100][101]. As shown in Table 4, acid leaching has been extensively exploited to extract REEs from coal combustion ash, and often the ash materials must be chemically and/or thermally treated prior to acid leaching to achieve better extraction performance.…”

Section: Chemical Extraction Of Rees From Coal Combustion Ashmentioning

confidence: 99%

A Comprehensive Review of Rare Earth Elements Recovery from Coal-Related Materials

et al. 2020

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Many studies have been published in recent years focusing on the recovery of rare earth elements (REEs) from coal-related materials, including coal, coal refuse, coal mine drainage, and coal combustion byproducts particularly fly ash. The scientific basis and technology development have been supported by coal geologists and extractive metallurgists, and through these efforts, the concept has progressed from feasibility assessment to pilot-scale production over the last five years. Physical beneficiation, acid leaching, ion-exchange leaching, bio-leaching, thermal treatment, alkali treatment, solvent extraction, and other recovery technologies have been evaluated with varying degrees of success depending on the feedstock properties. In general, physical beneficiation can be a suitable low-cost option for preliminary upgrading; however, most studies showed exceedingly low recovery values unless ultrafine grinding was first performed. This finding is largely attributed to the combination of small RE-bearing mineral particle size and complex REE mineralogy in coal-based resources. Alternatively, direct chemical extraction by acid was able to produce moderate recovery values, and the inclusion of leaching additives, alkaline pretreatment, and/or thermal pretreatment considerably improved the process performance. The studies reviewed in this article revealed two major pilot plants where these processes have been successfully deployed along with suitable solution purification technologies to continuously produce high-grade mixed rare earth products (as high as +95%) from coal-based resources. This article presents a systematic review of the recovery methods, testing outcomes, and separation mechanisms that are involved in REE extraction from coal-related materials. The most recent findings regarding the modes of occurrence of REEs in coal-related materials are also included.

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Section: Chemical Extraction Of Rees From Coal Combustion Ashmentioning

confidence: 99%

A Comprehensive Review of Rare Earth Elements Recovery from Coal-Related Materials

et al. 2020

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“…At the first stage of processing ash and slag materials, the method of leaching them with mineral acids is traditionally used. Sulfuric or nitric acids are most often used as reagents [6][7][8][9][10][11][12][13][14][15]. In order to increase the concentration of valuable components to recoverable rate, it is necessary to process the waste, considering it in the same quality as conventional mineral raw materials.…”

Section: Introductionmentioning

confidence: 99%

Recovery of valuable components from coal consumption waste

Cherkasova

Tikhomirova

et al. 2021

E3S Web Conf.

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Today, more than 56% of all coal in Russia is mined in Kuzbass. As a result of its burning, about half a million ash and slag waste (ASW) is generated per year. Ash dumps with such waste are constantly dusting; mobile ions of inorganic substances are washed away by precipitation, polluting the environment. Burned coals, being natural sorbents, contain impurities of many valuable elements, including rare-earth and precious metals, while their content in ash increases several times and can reach payable concentrations. Therefore, it is necessary to develop a technology for recovery of valuable components from ash and slag and using the remaining ash mass in construction and fertilizer industries. The efficiency of flotoextraction and chemical concentration methods for recovery of valuable components is assessed in the paper. The composition of the initial ash and slag samples and the resulting products of their processing were analyzed using infrared spectroscopic and optical emission methods.

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“…Within this context, there have been studies validating the technical feasibility of coal and coal byproducts as alternative sources for REEs [9][10][11][12][13][14][15][16][17][18][19]. The average rare earth concentration in coal and coal-based materials varies between 270 and 1480 mg/kg [13,20], while the concentration in the U.S. coals was indicated as 62.1 mg/kg [21]. However, regardless of their primary or newly-identified sources, the extraction of rare earth elements has always created environmental concerns.…”

Section: Introductionmentioning

confidence: 99%

Separation of Radionuclides from a Rare Earth-Containing Solution by Zeolite Adsorption

Talan

Huang

2020

Minerals

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The increasing industrial demand for rare earths requires new or alternative sources to be found. Within this context, there have been studies validating the technical feasibility of coal and coal byproducts as alternative sources for rare earth elements. Nonetheless, radioactive materials, such as thorium and uranium, are frequently seen in the rare earths’ mineralization, and causes environmental and health concerns. Consequently, there exists an urgent need to remove these radionuclides in order to produce high purity rare earths to diversify the supply chain, as well as maintain an environmentally-favorable extraction process for the surroundings. In this study, an experimental design was generated to examine the effect of zeolite particle size, feed solution pH, zeolite amount, and contact time of solid and aqueous phases on the removal of thorium and uranium from the solution. The best separation performance was achieved using 2.50 g of 12-µm zeolite sample at a pH value of 3 with a contact time of 2 h. Under these conditions, the adsorption recovery of rare earths, thorium, and uranium into the solid phase was found to be 20.43 wt%, 99.20 wt%, and 89.60 wt%, respectively. The Freundlich adsorption isotherm was determined to be the best-fit model, and the adsorption mechanism of rare earths and thorium was identified as multilayer physisorption. Further, the separation efficiency was assessed using the response surface methodology based on the development of a statistically significant model.

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Techno-economic analysis of supercritical extraction of rare earth elements from coal ash

Cited by 87 publications

References 37 publications

A Comprehensive Review of Rare Earth Elements Recovery from Coal-Related Materials

A Comprehensive Review of Rare Earth Elements Recovery from Coal-Related Materials

Recovery of valuable components from coal consumption waste

Separation of Radionuclides from a Rare Earth-Containing Solution by Zeolite Adsorption

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