• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.407-412
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• 1998

This study was carried out to investigate the optimum leaching conditions for the sulfation and water leaching, and separation of cerium from rare earth elements in leached solution by acid-adjusting method. The optimum conditions for the sulfation and water leaching from bastnasite concentrates are that the equivalent ration of sulfuric acid to concentrates is 2.5, calcination temperature and time are $600^{\circ}C$ and 2 hrs respectively, and the pulp density in the water leaching is 9.1%. The yield of rare earth oxide is about 93% at the above condition. The process of recovery of cerium hydroxide from leached solution by acid-adjusting method was carried out as following steps. The first step is the oxidation of the solution at pH 5 by using twice the equivalent of $H_2O_2$ solution as an oxidant. The second step is the precipitation to obtain cerium complex salt and cerium hydroxide after lowering the solution to pH 2. The last step is the oxidation-precipitation by using equivalent of $H_2O_2$ solution. From these results, it was possible to prepare cerium hydroxide with the yield of 60% and the quality of 80%.

• Membrane Journal
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• v.32 no.1
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• pp.13-22
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• 2022

Ever increasing global energy demand gives rise to uncontrollable environmental pollution. Demand on fossil fuel and consequent carbon emission leads to global warming and climate change. Nuclear energy is an alternative source to generate clean energy but mining of nuclear fuel is associated with harmful chemicals. Mining of valuable minerals from sea water by membrane separation process is a cost effective along with environmental friendly process. Separation and adsorption based mining of valuable minerals from sea water are another efficient process. Recovery of actinides from rare earth elements are very challenging and expensive process. Pressure driven membrane separation process is economically more viable along with environmental process. In this review membrane separation process are based on polyether sulfone, polyamide, polyimide, polyamidoxine and hybrid membranes. In case of adsorption process, mainly amidoxime kind of adsorbent are discussed.

• Resources Recycling
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• v.32 no.6
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• pp.54-66
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• 2023

Titanium's importance as a mineral resource is increasing, but the Korean industry depends on imports. Ilmenite is the principal titanium ore. However, research and development from raw materials have not been investigated yet in detail. Hence, measures to secure a stable titanium supply chain are urgently needed. Accordingly, through beneficiation technology, we evaluated the possibility of technological application for the efficient recovery of valuable minerals. As a result of the experiments, we confirmed that mineral particles existed as fine particles due to weathering, making recovery through classification difficult. Consequently, applying beneficiation technologies, i.e., specific gravity separation, magnetic separation, and flotation, makes it possible to recover valuable minerals such as hematite and rutile. However, there are limitations in increasing the quality and yield of TiO₂ due to the mineralogical characteristic of the hematite and rutile contained in titanium ore. Hametite is combined with rutile even at fine particles. Therefore, it is essential to develop mineral processing routes, to recover iron, vanadium, and rare earth elements as resources. On that account, we used grinding technology that improves group separation between constituent minerals and magnetic separation technology that utilizes the difference in magnetic sensitivity between fine mineral particles. The development of beneficiation technology that can secure the economic feasibility of valuable materials after reforming iron oxide and titanium oxide components is necessary.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.5
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• pp.211-216
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• 2018

The recovery of rare earth elements (REE) including La, Nd and Ce from spent batteries is important issues to reuse scarce resources. Herein, we present a simple recovery process to obtain lanthanum oxide ($La_2O_3$) from spent Ni-MH batteries, and demonstrate the conversion mechanism from $NaLa(SO_4)_2{\cdot}H_2O$ to $La_2O_3$. This strategy requires the initial preparation of $NaLa(SO_4)_2{\cdot}H_2O$ and subsequent metathesis reaction with $Na_2CO_3$ at $70^{\circ}C$. This metathesis reaction resulted in the crystalline lanthanum carbonate hydrate ($La_2(CO_3)_3{\cdot}xH_2O$) powder with plate-like morphology. On the basis of TGA result, the $La_2(CO_3)_3{\cdot}xH_2O$ powder was calcined in air at three different temperatures, that is, $300^{\circ}C$, $500^{\circ}C$, and $1000^{\circ}C$. As the calcination temperature increased, the morphology of powder was changed; prism-like ($NaLa(SO_4)_2{\cdot}H_2O$) ${\rightarrow}$ platelike ($La_2(CO_3)_3{\cdot}xH_2O$) ${\rightarrow}$ aggregated irregular shape ($La_2O_3$). Futhermore, XRD results indicated that the crystalline $La_2O_3$ could be synthesized after the metathesis reaction with $Na_2CO_3$, followed by heat-treatment at $1000^{\circ}C$, along with a change of crystallographic structures; $NaLa(SO_4)_2{\cdot}H_2O$ ${\rightarrow}$ $La_2(CO_3)_3{\cdot}xH_2O$ ${\rightarrow}$ $La_2O_3$.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.46-52
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• 2015

A leaching kinetics was conducted for the purpose of recovery of praseodymium in sulfuric acid ($H_2SO_4$) from REE slag concentrated by the smelting reduction process in an arc furnace as a reactant. The concentration of $H_2SO_4$ was fixed at an excess ratio under the condition of slurry density of 1.500 g slag/L, 0.3 mol $H_2SO_4$, and the effect of temperatures was investigated under the condition of 30 to $80^{\circ}C$. As a result, praseodymium oxide ($Pr_6O_{11}$) existing in the slag was completely converted into praseodymium sulfate ($Pr_2(SO_4)_3{\cdot}8H_2O$) after the leaching of 5 h. On the basis of the shrinking core model with a shape of sphere, the first leaching reaction was determined by chemical reaction mechanism. Generally, the solubility of pure REEs decreases with the increase of leaching temperatures in sulfuric acid, but REE slag was oppositely increased with increasing temperatures. It occurs because the ash layer included in the slag is affected as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction was determined to be $9.195kJmol^{-1}$. In the second stage, the leaching rate is determined by the ash layer diffusion mechanism. The apparent activation energy of the second ash layer diffusion was determined to be $19.106kJmol^{-1}$. These relative low activation energy values were obtained by the existence of unreacted ash layer in the REE slag.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.323-336
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• 2023

We investigated the nickel potential and genesis of ultramafic rocks in the Yugu area to secure nickel resources in South Korea. The Yugu ultramafic rocks, located in the southwest of the Gyeonggi Massif, are characterized by spinel peridotite and exhibit strong serpentinization along their boundaries. The serpentinization is observed as olivine transformed to antigorite and chrysotile, while pentlandite, the nickel sulfide mineral, altered into millerite and awaruite. Serpentine displays distinct foliation, aligning subparallel to the ultramafic rock boundaries and foliation of Yugu gneiss. This suggests that the uplift of ultramafic rocks resulted in hydrothermal infiltration likely sourced from the Yugu gneiss metamorphism. The Yugu ultramafic rocks are residues after 5~18% partial melting of abyssal peridotite. Enriched light rare earth elements and Eu imply secondary metasomatism. Geochemistry suggests a link between the formation of Yugu ultramafic rock and the Triassic collision of the North and South China continents. The nickel content is around 0.17~0.21%, mainly contained in olivine and serpentine. Hence, in addition to the mineral processing study on the sulfide minerals, focused studies on oxide minerals for enhanced nickel recovery within the Yugu ultramafic rock are strongly suggested.