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

Ma, Yiqian; Stopić, Srečko; Gronen, Lars; Milivojević, Milovan; Obradović, Srdjan; Friedrich, Bernd

doi:10.3390/met8040267

Cited by 29 publications

(13 citation statements)

References 39 publications

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“…The main challenge is avoiding the formation of silica gel, which is non-filterable when using acid to extract REE. Ma et al [7] have studied neural network modeling for the optimization of the extraction of rare earth elements from the Eudialyte concentrate by dry digestion and a subsequent leaching avoiding the formation of silica gel in the presence of the hydrochloric acid.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Nanosilica via Olivine Mineral Carbonation under High Pressure in an Autoclave

Stopić

Dertmann

Koiwa

et al. 2019

Metals

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Silicon dioxide nanoparticles, also known as silica nanoparticles or nanosilica, are the basis for a great deal of biomedical and catalytic research due to their stability, low toxicity and ability to be functionalized with a range of molecules and polymers. A novel synthesis route is based on CO2 absorption/sequestration in an autoclave by forsterite (Mg2SiO4), which is part of the mineral group of olivines. Therefore, it is a feasible and safe method to bind carbon dioxide in carbonate compounds such as magnesite forming at the same time as the spherical particles of silica. Indifference to traditional methods of synthesis of nanosilica such as sol gel, ultrasonic spray pyrolysis method and hydrothermal synthesis using some acids and alkaline solutions, this synthesis method takes place in water solution at 175 °C and above 100 bar. Our first experiments have studied the influence of some additives such as sodium bicarbonate, oxalic acid and ascorbic acid, solid/liquid ratio and particle size on the carbonation efficiency, without any consideration of formed silica. This paper focuses on a carbonation mechanism for synthesis of nanosilica under high pressure and high temperature in an autoclave, its morphological characteristics and important parameters for silica precipitation such as pH-value and rotating speed.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Nanosilica via Olivine Mineral Carbonation under High Pressure in an Autoclave

Stopić

Dertmann

Koiwa

et al. 2019

Metals

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“…Project designs for acid digestion of eudialyte concentrate contained different experiments three trials at the beginning according to the experience with different reaction parameters including the next optimal parameters: the ratio of HCl: eudialyte concentrate, weight of water and concentrate, leaching temperature, and reaction time during acid digestion process [66]. The hydrochloric acid for acid digestion (cHCl) to eudialyte concentrate ratio, mass of water for leaching (cH 2 O) to mass of eudialyte concentrate ratio, leaching temperature (T) and leaching time (t) as the predictor variables, and the total rare earth elements (TREE) extraction efficiency as the response were in laboratory and scale up conditions by Ma et al [67] considered in detail. 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).…”

Section: Application Of the Unit Operations In Primary Metallurgy Of Ree 21 Treatment Of An Eudialyte Concentrate With Precipitation And mentioning

confidence: 99%

Advances in Understanding of the Application of Unit Operations in Metallurgy of Rare Earth Elements

Stopić

Friedrich

2021

Metals

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Unit operations (UO) are mostly used in non-ferrous extractive metallurgy (NFEM) and usually separated into three categories: (1) hydrometallurgy (leaching under atmospheric and high pressure conditions, mixing of solution with gas and mechanical parts, neutralization of solution, precipitation and cementation of metals from solution aiming purification, and compound productions during crystallization), (2) pyrometallurgy (roasting, smelting, refining), and (3) electrometallurgy (aqueous electrolysis and molten salt electrolysis). The high demand for critical metals, such as rare earth elements (REE), indium, scandium, and gallium raises the need for an advance in understanding of the UO in NFEM. The aimed metal is first transferred from ores and concentrates to a solution using a selective dissolution (leaching or dry digestion) under an atmospheric pressure below 1 bar at 100 °C in an agitating glass reactor and under a high pressure (40–50 bar) at high temperatures (below 270 °C) in an autoclave and tubular reactor. The purification of the obtained solution was performed using neutralization agents such as sodium hydroxide and calcium carbonate or more selective precipitation agents such as sodium carbonate and oxalic acid. The separation of metals is possible using liquid (water solution)/liquid (organic phase) extraction (solvent extraction (SX) in mixer-settler) and solid-liquid filtration in chamber filter-press under pressure until 5 bar. Crystallization is the process by which a metallic compound is converted from a liquid into a crystalline state via a supersaturated solution. The final step is metal production using different methods (aqueous electrolysis for basic metals such as copper, zinc, silver, and molten salt electrolysis for REE and aluminum). Advanced processes, such as ultrasonic spray pyrolysis, microwave assisted leaching, and can be combined with reduction processes in order to produce metallic powders. Some preparation for the leaching process is performed via a roasting process in a rotary furnace, where the sulfidic ore was first oxidized in an oxidic form which is a suitable for the metal transfer to water solution. UO in extractive metallurgy of REE can be successfully used not only for the metal wining from primary materials, but also for its recovery from secondary materials.

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“…Dissolution with high concentrated acid (10−12 mol/L) at room temperature was followed with an exothermic reaction, which was sufficient for the dissolution of eudialyte minerals. Stopic et al [13][14][15] have studied the optimization of dry digestion of eudialyte concentrate with hydrochloric acid using regression analysis and an artificial neural network. They performed a scale-up of the dry digestion process producing new concentrate based on rare earth carbonate from the Tanbreez eudialyte concentrate containing 31% 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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Neural Network Modeling for the Extraction of Rare Earth Elements from Eudialyte Concentrate by Dry Digestion and Leaching

Cited by 29 publications

References 39 publications

Synthesis of Nanosilica via Olivine Mineral Carbonation under High Pressure in an Autoclave

Synthesis of Nanosilica via Olivine Mineral Carbonation under High Pressure in an Autoclave

Advances in Understanding of the Application of Unit Operations in Metallurgy of Rare Earth Elements

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

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