Selective silica gel free scandium extraction from Iron-depleted red mud slags by dry digestion

Alkan, Gözde; Yagmurlu, Bengi; Gronen, Lars; Dittrich, Carsten; Ma, Yiqian; Stopić, Srečko; Friedrich, Bernd

doi:10.1016/j.hydromet.2019.03.008

Cited by 38 publications

(22 citation statements)

References 21 publications

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“…Similarly, high Si content in red mud and its slags produced by pyrometallurgical treatment for the Fe removal makes these secondary resources untreatable with conventional acid leaching routes due to the formation of silica gel. Alkan et al [5] studied red mud and slags synthesized by electric arc furnace smelting, which contain rather moderate and extensive SiO 2 . In the next step, the formed slag was exposed separately by red mud to dry digestion with sulfuric acid at room temperature aiming at selective Sc recovery without Ti and Si dissolution.…”

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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“…Particle size distribution was obtained using QEMSCAN based image analysis 25 . Thereby, multi-phase particles where extracted virtually from the recoded field images.…”

Section: Methodsmentioning

confidence: 99%

“…Fe recovery from red mud can be achieved by electric arc furnace (EAF) smelting yielding Fe recoveries of 95% with pig iron as the main product and a slag enriched in Sc, Ti and REEs with desired crystallinity and chemistry as the by-product. The type and amount of fluxing agents added during smelting and the cooling rates after smelting have a crucial role in the conditioning of the produced slags 23–25 .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Scandium Phosphate after Peroxide Assisted Leaching of Iron Depleted Bauxite Residue (Red Mud) Slags

Yagmurlu

Alkan

Xakalashe

et al. 2019

Sci Rep

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Anticipated future demand and limited primary sources of Sc highlight the importance of secondary Sc resources such as bauxite residue (red mud). In this study, a process route starting from red mud aiming to recover Sc as a concentrate by a combination of pyrometallurgical and hydrometallurgical processes was developed. Bauxite residue was treated in an electric arc furnace (EAF) for Fe removal as well as slag conditioning with varying flux additions and various cooling conditions. 95% of iron recovery to the metal was achieved. Resulting slags were subjected to identical H 2 O 2 supported H 2 SO 4 leaching conditions at 75 °C. The effect of slag mineralogy and crystallinity on the leaching efficiencies were investigated using XRD and QEMSCAN analysis. As a result of the highly amorphous nature of acidic slags, maximum of 72% Sc leaching was obtained. For leached slags, water quenched basic slag was found to be the most promising condition resulting in an extreme Sc leaching yield of 97% and this slag was selected for the further Sc precipitation. High impurity removal rates and selective Sc separation were achieved with a triple-stage successive precipitation to synthesize a Sc concentrate. Starting from EAF treatment followed by leaching and precipitation, 85% of the initial Sc in the red mud was successfully recovered as Sc phosphate.

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“…This work belongs to the EURARE project that focuses on producing REE within Europe and reducing the external supply [16]. An extraction of scandium from red mud was studied by Alkan et al [16][17][18][19][20], confirming that dry digestion was successfully used to prevent a silica gel formation, simultaneously providing a high leaching efficiency of the rare earth elements.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, from 2013, several research projects have started in Europe (EREAN, REDMUD; EURARE, SCALE and REMOVAL) in order to study the prevention of silica gel formation and reach a high extraction of rare earth elements from eudialyte, red mud and slags after the smelting of red mud [16][17][18][19][20]. This work belongs to the EURARE project that focuses on producing REE within Europe and reducing the external supply [16].…”

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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Selective silica gel free scandium extraction from Iron-depleted red mud slags by dry digestion

Cited by 38 publications

References 21 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

Synthesis of Scandium Phosphate after Peroxide Assisted Leaching of Iron Depleted Bauxite Residue (Red Mud) Slags

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

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