Leaching of rare earth elements from eudialyte concentrate by suppressing silica gel formation

Davris, Panagiotis; Stopić, Srečko; Balomenos, Efthymios; Panias, Dimitrios; Paspaliaris, Ioannis; Friedrich, Bernd

doi:10.1016/j.mineng.2016.12.011

Cited by 74 publications

(45 citation statements)

References 20 publications

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“…The chosen parameters were proposed concerning the previous experimental work at the EURARE Project [11], literature data [17,24], and high experience of the authors in hydrometallurgy.…”

Section: Experiments and Obtained Measurements Of Process Outputsmentioning

confidence: 99%

“…Except the secondary resources, a variety of potential unconventional deposits have also been explored, such as REE-bearing laterite, peralkaline granite, ferromanganese nodules, and silicate deposits, including eudialyte, mosandrite, and britholite [13][14][15][16]. Among the minerals mentioned, Eudialyte is a promising REE resource, which contains 1.5-2% REE [17]. Eudialyte is a somewhat complicated cyclosilicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites.…”

Section: Introductionmentioning

confidence: 99%

“…According to the latest research [17], fuming ("Dry digestion at temperatures about 100 • C"), the addition of an acidic solution to heated eudialyte concentrate, and the subsequent water leaching of the treated concentrate could result to the high recovery of REE with avoiding silica gel formation. Moreover, in the mentioned paper, Davris et al studied hydrometallurgical processing of eudialyte bearing concentrates, using high concentrated acid to recover rare earth elements via low-temperature dry digestion to prevent silica gel formation.…”

Section: Introductionmentioning

confidence: 99%

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Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

Stopić

Gronen

et al. 2018

Metals

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Eudialyte is a promising mineral for rare earth elements (REE) extraction due to its good solubility in acid, low radioactive, and relatively high content of REE. In this paper, a two stage hydrometallurgical treatment of eudialyte concentrate was studied: dry digestion with hydrochloric acid and leaching with water. The hydrochloric acid for dry digestion to eudialyte concentrate ratio, mass of water for leaching to mass of eudialyte concentrate ratio, leaching temperature and leaching time as the predictor variables, and the total rare earth elements (TREE) extraction efficiency as the response were considered. After experimental work in laboratory conditions, according to design of experiment theory (DoE), the modeling process was performed using Multiple Linear Regression (MLR), Stepwise Regression (SWR), and Artificial Neural Network (ANN). The ANN model of REE extraction was adopted. Additional tests showed that values predicted by the neural network model were in very good agreement with the experimental results. Finally, the experiments were performed on a scaled up system under optimal conditions that were predicted by the adopted ANN model. Results at the scale-up plant confirmed the results that were obtained in the laboratory.

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“…The chosen parameters were proposed concerning the previous experimental work at the EURARE Project [11], literature data [17,24], and high experience of the authors in hydrometallurgy.…”

Section: Experiments and Obtained Measurements Of Process Outputsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

Stopić

Gronen

et al. 2018

Metals

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“…Davris et al [11] have reported some difficulties in treating with this kind of silicate ore, because of the formation of silica gel that prevents filtration and thus stops the whole experiment process. In his previous study, the dry digestion treatment (called "fuming" process) at 100 • C was successfully used to prevent the formation of silica gel, providing a high leaching efficiency of rare earth elements.…”

Section: Introductionmentioning

confidence: 99%

Valorization of Rare Earth Elements from a Steenstrupine Concentrate Via a Combined Hydrometallurgical and Pyrometallurgical Method

Yun¹,

Stopić²,

Friedrich³

2020

Minerals

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Due to their unique characteristics, Lanthanides series (15 elements) together with scandium and yttrium are used as critical metals in numerous applications such as energy sources, catalysts, hybrid cars, medical technology, and military industry. The significance of rare earth elements has been continuously increasing because the global demand for producing high-tech devices is continuously rising. The recovery of rare earth oxide from concentrate based on eudialyte and steenstrupine was performed using a hydrometallurgical and pyrometallurgical method. Eudialyte and steenstrupine are a complex Na-Ca-zirconosilicate mineral containing rare earth elements (REEs), Zr, Hf and Nb, thus serving as a potential source of Zr. Because of the presence of silica in eudialyte, the main challenge in its processing is avoiding silica gel formation, which is an unfilterable solid residue. The influence of leaching temperature, time and solid-liquid ratio on leaching efficiency was studied in laboratory conditions. A new research strategy was developed in order to recover rare earth elements using hydrochloric acid, avoiding silica gel formation.

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“…Several approaches have been described dealing with leaching of REEs from EGMs [9][10][11] and with REE separation from the resulting system [12][13][14][15] so far. A silica-free solution can be obtained by the pre-treatment of eudialyte with concentrated acid and subsequent water leaching.…”

Section: Introductionmentioning

confidence: 99%

Selective Leaching of Rare Earth Elements (REEs) from Eudialyte Concentrate after Sulfation and Thermal Decomposition of Non-REE Sulfates

et al. 2019

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Eudialyte, a sodium rich zirconosilicate, is one of the promising sources for REEs (rare earth elements), particularly for HREEs + Y (heavy rare earth elements and yttrium). The key challenge in hydrometallurgical processing is the prevention of silica gel formation and REE separation from resulting multi-element leach solutions. This study deals with the selective extraction of REE from eudialyte concentrate by selective roasting. In this method, metal ions are converted into sulfates, followed by the decomposition of non-REE sulfates in a roasting step and the water leaching of the calcine. The effect of acid addition, roasting temperature, roasting time, pulp density and leaching time is studied. For sufficient conversion of REEs into sulfates, sulfuric acid is added in excess. At a roasting temperature of ≥750 • C sulfates of zirconium, hafnium, niobium, aluminum and iron decompose into sparingly soluble compounds, while REE and manganese sulfates remain stable up to a roasting time of 120 min. The silica present in the calcine is found to be metastable even after roasting. The amount of leached Si 4+ is dependent predominantly on the pH value of the leaching medium. Applying the method, REEs can be efficiently separated from zirconium, hafnium, niobium, aluminum and iron. However, only diluted solutions can be produced. Water leaching of calcine at high solid/liquid ratios causes REE losses resulting from formation of double sulfates and gypsum. The acid excess removed from the reaction mixture in the roasting stage can be simply recovered by treatment of the gas phase.Minerals 2019, 9, 522 2 of 12 including permanent loss of ecosystem, severe soil erosion, air pollution, biodiversity loss and human health problems [5].Another promising sources for HREEs + Y are some peralkaline and apatite deposits. Generally, they contain higher amounts of REEs in comparison to ion-adsorption type deposits (peralkaline deposits ≤2 wt %; apatite deposits ≤1.5 wt %) [6]. However, due to the complex mining and extraction processes they have not gained industrial significance so far. Eudialyte group minerals (EGMs)-sodium rich silicates occurring in peralkaline deposits-are used sporadically as zirconium ore and are often enriched with REEs. The development of innovative approaches for the extraction of REEs from EGMs or apatite is of great importance for securing strategic raw materials supply and could revolutionize the rare earth market [1].EGMs are characterized by low melting temperature and high solubility in diluted mineral acids [7]. The low resistance to acids makes eudialytes amenable for cheap leaching [8]. However, during leaching high amounts of silicic acid are released, which tends to gelate. To obtain a silica-free solution more demanding methods are required [9]. Furthermore, efficient and low priced subsequent separation of individual components from resulting multi-element solutions is a big challenge. Several approaches have been described dealing with leaching of REEs from EGMs [9-11] and with REE separati...

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Leaching of rare earth elements from eudialyte concentrate by suppressing silica gel formation

Cited by 74 publications

References 20 publications

Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

Valorization of Rare Earth Elements from a Steenstrupine Concentrate Via a Combined Hydrometallurgical and Pyrometallurgical Method

Selective Leaching of Rare Earth Elements (REEs) from Eudialyte Concentrate after Sulfation and Thermal Decomposition of Non-REE Sulfates

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