Critical mineral development involves not only resource availability but also policy coordination and governance challenges across the supply chain. This study examines how stakeholders' policy perceptions shape the demand for a coordination body in domestic critical mineral development in Korea. Using survey data from 515 respondents representing various segments of the critical mineral value chain and related policy communities, the study employs partial least squares structural equation modeling (PLS-SEM) to analyze the structural relationships among key perception variables. The results indicate that perceptions of the necessity of domestic development and recognition of structural problems in the current system significantly strengthen perceptions of the need for policy and institutional reform. These policy perceptions, in turn, increase support for government policy measures and supply-chain strategies, including international cooperation and domestic capability building. Both factors significantly increase the perceived need for a coordination body to align policy instruments and value-chain strategies. Additional robustness analysis shows that preferences regarding the actor responsible for project implementation do not directly influence this governance demand. By conceptualizing policy perception as a sequential and structural process - spanning problem diagnosis, institutional reform demands, policy instrument preferences, and governance needs - this study advances beyond approaches that treat policy perceptions as parallel, independent attitude variables. These findings suggest that a coordination body is demanded primarily as an institutional mechanism to integrate policy instruments and supply-chain strategies rather than as a reflection of actor preferences in critical mineral development.

The utilization of surrounding rocks is required in human living areas, and these development activities create large cut slopes and generate large amounts of cut rocks as construction materials. If these development areas are strata containing sulfide minerals (pyrite, etc.), contamination may occur, causing environmental pollution problems in the development site and surrounding areas. Several methods have been studied for the preliminary identification of potentially contaminated rocks, including Acid Base Accounting (ABA), Modified ABA procedures, Carbonate Neutralization Potential determinations, Humidity cell tests, Column tests, Batch reactor (Shake flask) tests, and Field tests (Orava, 1997; USEPA and Hardrock Mining, 2003). Studies on rock samples have resulted in most of the samples being classified as Non-Acid Forming (NAF), with some samples containing sulfide minerals (such as pyrite) being classified as Potentially Acid Forming (PAF). It can be expected that future development of these rocky areas may affect the surrounding environment or rock utilization. Therefore, these rock areas are considered to be in need of management. It would be desirable to investigate the occurrence of pollution sources caused by mineral sulfides in advance and take appropriate countermeasures. It is expected to reduce the economic losses that may occur in the future, and it is judged that the pollution problem of the surrounding environment can be further reduced.

A nationwide low-density geochemical map of arsenic was created using 723 composite stream sediment samples, and the geochemical distribution of arsenic was evaluated based on the map. The low-density composite samples, which were obtained from high-density stream sediment samples (23,696 samples) collected from the previous national geochemical mapping project, were used as a geological medium. To this end, each 1:50,000 topographic map of the entire country was divided into six sub-regions, and all individual stream sediment samples within each sub-region were mixed to create one composite sample (953 in total, approximately 1/100 km(2)). Chemical analysis was performed using a high resolution inductively coupled plasma-mass spectrometer (HR ICP-MS) after strong acid digestion (HF, HClO4, and HNO3), and strict quality control was applied. As a result, arsenic had an interquartile range (Q25 similar to Q75) of 4.53 similar to 7.99 mg/kg, a median of 5.78 mg/kg and a mean of 8.95 mg/kg. The geochemical threshold using the box plot of arsenic content was derived as 18.7 mg/kg, and approximately 3.5% of the samples exceeded this value. The nationwide spatial distribution of arsenic content shows a wide range of fluctuation patterns by geology, reflecting the underlying geological variations. The geochemical anomalies above the threshold indicate the influence of representative non-ferrous metal mineralization zones in Korea.

This study investigates the mineralogical and chemical properties of arsenic-contaminated soils from an abandoned gold mine in South Korea, utilizing a combination of synchrotron-based X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and conventional analytical techniques. Quantitative XRD (QXRD) results indicate that the soils are primarily composed of quartz and mica, with varying contents of dolomite, talc, and chlorite depending on particle size. These QXRD findings are strongly supported by polarizing microscopy, which visually confirmed mineral occurrences, and by X-ray fluorescence (XRF) analysis, which revealed consistent elemental compositions. XAS analysis revealed that arsenic predominantly exists in the form of scorodite (FeAsO42H(2)O), along with minor fractions of arsenopyrite (FeAsS) and adsorbed arsenate species. High arsenic concentrations, particularly in fine particles (<75 mu m), raise concerns for potential environmental dispersion via wind and water erosion. Additionally, the study confirms that under slightly alkaline conditions (pH 8.1), arsenate species readily leach from soil, indicating limited natural attenuation in the studied area. The findings emphasize the need for effective containment strategies, and highlight the utility of synchrotron X-ray techniques in environmental geoscience for understanding contaminant behavior at a molecular level.

Soil contamination with metalloids such as arsenic (As) and antimony (Sb) and heavy metals such as lead (Pb) in agricultural area surrounding mines affects growth of crops. Because As and Sb are stabilized by iron (Fe) hydroxide and heavy metals are stabilized by phosphate, iron phosphate-coated biochar (IPCB) simultaneously stabilizes metal(loid)s and prevents detrimental effect of metal(loid)s on crops. Therefore, the objective of the study was to evaluate lettuce growth followed by metal stabilization in soil by treating metal contaminated soil with IPCB. The lettuce grown in single and mixed metal(loid)-contaminated soil treated with IPCB showed higher dry biomass, chlorophyll content measured by soil plant analysis development (SPAD) meter, and Fv/Fm values than without IPCB indicating that IPCB mitigated toxic effect of metal(loid)s. The IPCB decreased bioavailable As, Sb, and Pb by 40.8 ± 3.0

Carbon dioxide (CO2)-assisted 2 )-assisted thermal conversion of C-containing wastes can bring synergistic effect of CO2 2 reduction/consumption and valuable resources (e.g., e.g ., syngas) recovery of from the wastes, and provide a solid option for the sustainable treatment. In this study, the effects of iron oxides on CO2-assisted 2-assisted pyrolysis of oxygen- free plastics (polyethylene, PE) for syngas generation were investigated. Without the addition of iron oxides, no notable CO production was observed during CO2-assisted 2-assisted PE pyrolysis (non-isothermal zone of 200-700 degrees C for 50 min, followed by isothermal zone of 700 degrees C). Compared with the CO2-assisted 2-assisted thermochemical conversion of PE in the presence of Fe3O4 3 O 4 at a mass ratio of 1:1 (0.3 mol% H2 2 and 0.6 mol% CO), syngas generation by gamma- Fe 2 O 3 at the same mass ratio (0.6 mol% H2 2 and 2.5 mol% CO) is enhanced at a maximum temperature of 700 degrees C due to the higher surface reducibility, which facilitates a larger amount of thermal cracking of hydrocarbons. In conclusion, iron oxides with high oxidation states are promising catalysts for the production of CO-rich syngas during CO2-assisted 2-assisted pyrolysis of oxygen-free plastics.

This study presents the synthesis and characterization of MgAl-layered double hydroxide (LDH)/rice husk hydrochar (RHH) nanocomposites (MgAl-LDH/RHHs) via an in situ one-pot hydrothermal route at 150 degrees C, utilizing Mg:Al molar ratio of 2:1 for arsenic remediation. The formation of MgAl-LDH/RHHs and their physicochemical properties were evaluated under varying hydrothermal aging times systematically. Prolonging the aging period to 12 hrs significantly enhanced the crystallinity and crystal size of the LDHs, resulting in a 3D hierarchical structure with the highest specific surface area (27.98 m(2)/g) formed on the hydrochar surface. The hexagonal crystal structure (d(003) = 0.8246 nm) was characterized by a rhombohedral unit cell with lattice parameters a = 0.3049 nm and c = 2.4738 nm, and a high positive charge density of 4.284 e/nm(2). These properties were found to be favorable for the sorption of arsenic oxyanions. Batch adsorption experiments were conducted to assess the potential of MgAl-LDH/RHHs-12h for the remediation of arsenic-contaminated soils. The original soil sample (CY) was mechanically sieved into fine-grained (CYF, < 75 mu m) and coarse-grained (CYC, 75 mu m-2 mm) fractions. When these soil samples were reacted with deionized water, arsenate was identified as the dissolved arsenic species, with concentrations of 2.85 mg/L for CY, 4.02 mg/L for CYF, and 2.55 mg/L for CYC, respectively. Kinetic sorption experiments, conducted at pH 5.0 and 8.0 in the presence and absence of 0.1 M NaCl as a background electrolyte, revealed that arsenic sorption onto MgAl-LDH/RHHs-12h was inhibited at pH 8 in the presence of NaCl. These findings suggest that effective arsenic sorption requires low pH conditions with minimal background electrolytes in soils.

This study investigated the effect of hydrogen peroxide treatment on the removal pH for Fe, Al, and Mn and sludge production in the lime neutralization process. In the laboratory, the AMD collected from the coal mine was oxidized with 5% H2O2, and then neutralized to pH 3, 5, 7 and 9, respectively, with 20% lime slurry. In the control experiment, the same neutralization experiment was performed without H2O2 treatment. During the experiment, the supernatant was measured for pH and Eh and analyzed for Fe, Al, Mn, Ca and SO42- ions. Simple neutralization without H2O2 treatment up to pH 8 resulted in almost 100% Fe (<0.3 mg/L), Al (<0.3 mg/L), and Mn (2 mg/L) removal. Neutralization with pre H2O2 treatment also eliminated Fe and Al at pH 6 to the same removal efficiencies and Mn remained at 15 mg/L. The use of lime was 17% less and the weight of sludge was 35% less, and the volume of sludge decreased by 47%. As a result of evaluating the pH-Eh-Fe diagram for hydrogen peroxide/lime neutralization facilities, it was evaluated that Fe could be removed at pH 5-6. It can be concluded that neutralizing up to pH 6 after oxidation effectively minimizes the amount of sludge generated by removing Fe and Al and suppressing gypsum production.

This work aimed to magnetically harvest Microcystisaeruginosa (MA) in water using magnetic iron oxides and investigate the feasibility of utilizing algae/iron oxides mixture as feedstock in pyrolytic platform to produce syngas (H2 & CO) and metal biochar. Carbon dioxide (CO2) was used as a feeding gas to enhance the production efficiency of syngas and also functioned pH controller for better MA harvesting. Furthermore, the addition of magnetite (Fe3O4) and maghemite (γ-Fe2O3) at the stage of algae harvesting magnetically recovered MA from water in a relatively short period of time (~1 min). As a result, the use of CO2 and magnetic iron oxides in pyrolytic utilization of MA brought multiple benefits such as 1) more syngas generation by oxygen carrier role of Fe phase in CO2, 2) magnetic separation of MA supported by gas stream, and 3) adsorptive function of metal biochar for algal toxin (Microcystins).

With rising of harmful algae blooming and toxin exposure, practical utilization of harmful algae has been developed. This work aimed to magnetically harvest Microcystis aeruginosa (MA) using iron oxides and investigate the feasibility of algae/iron oxides mixture as feedstock in pyrolytic platform to produce syngas and metal biochar. Carbon dioxide (CO2) was used as a feeding gas to enhance the production efficiency of syngas and also functioned pH controller for better MA harvesting and toxin removal. CO2 support brought multiple benefits: magnetite (Fe3O4) and maghemite (γ-Fe2O3) recovered MA in a relatively short period of time (∼1 min), the recovered biomass generated 34-fold increased carbon monoxide, and metal biochar adsorbed higher amount of toxin from MA (2.8-fold). Pyrolytic utilization of harmful algae supported by CO2 and iron oxides could be one of promising techniques for evolution of metal biochar to remove toxin, while efficiently recover biomass and enhance syngas production.

Nation-wide low-density geochemical maps are being constructed using composite samples of stream sediments for 10 elements (As, Be, Bi, Cd, Mo, Sb, Sn, Tl, U, W) that have not been previously mapped at the national level. To obtain high-quality geochemical data, rigorous quality control (QC) procedures were implemented, which included (1) the randomization of project samples, (2) the introduction of project standards, and (3) the insertion and analysis of analytical replicates. Threshold values were calculated and geochemical maps were created for five elements (Be, Bi, Sn, Tl, U). The remaining five elements that did not pass the QC are currently undergoing re-analysis. Low-density geochemical mapping can result in a loss of detailed geochemical information, but it is useful for identifying regional geochemical patterns and establishing threshold values.

Nano Fe(III) oxide (FO) was employed as an additive material for CO2-aided pyrolysis of spent coffee grounds (SCG) and its impacts on the syngas (H2 & CO) generation and biochar adsorption characteristics were examined. Amendment of FO led to 153 and 682% increase of H2 and CO in pyrolytic process of SCG, respectively, which is deemed to arise from enhanced thermal cracking of hydrocarbons and oxygen transfer reaction mediated by FO. Incorporation of FO successfully created porous structure in the produced biochar. The adsorption tests revealed that the biochar exhibited bi-functional capability to remove both positively charged Cd(II) and Ni(II), and negatively charged Sb(V). The adsorption of Cd(II) and Ni(II) was hardly deteriorated in the multiple adsorption cycles, and the adsorption of Sb(V) was further enhanced through formation of surface ternary complexes. The overall results demonstrated nano Fe(III) oxide is a promising amendment material in CO2-aided pyrolysis of lignocellulosic biomass for enhancing syngas generation and producing functional biochar.

There are totally 5,396 mines located in South Korea, and 2,033 mines are presently closed or abandoned. According to the current status of mine hazard by mine damage type (2017) of the Korea Mine Rehabilitation and mineral Resources Corporation, mine hazard could be caused by tailings loss in 237 mines. Mining stream/void inside the mines are inevitably formed during resource development, and therefore the appropriate management for the mine stability is continuously needed. Mining filling is regarded as one of the best options since the filling mass acts as a secondary support material that can ensure the stability of the mine void and increase the yielding rate of mining. This study evaluated the suitability of harmless tailings, generated from mine development, as a paste backfill material to secure the stability of mine. The particle size of tailings collected at the tungsten mine used in the study was suitable to be used as a paste backfill materials. The strength of cement solidified using test materials was affected by the content of cement and curing duration of the backfill materials sample. It turned out that above 3.5% the cement content and curing for two weeks were an optimal condition to produce the safe cement. In the Environment Ministry's water pollutant emission acceptance standards (South Korea), the tested backfill materials passed all domestic standards for As, Cd, Cr+6, Pb, Cu, and Hg. The environmental/physical properties of tailings obtained from the results demonstrated that the use the tailings as a paste backfill material to fill the inner space of mines could be considered as a promising option. This evaluation results will contribute to the stabilization of mining enemies and restoration of mine damage in abandoned mine areas through economical and efficient treatment of tailings.

Nano Fe(III) oxide (FO) was used as an amendment material in CO2-assisted pyrolysis of spent coffee grounds (SCG) and its impacts on the syngas (H2 & CO) generation and biochar adsorptive properties were investigated. Amendment of FO led to 153 and 682% increase of H2 and CO in pyrolytic process of SCG, respectively, which is deemed to arise from enhanced thermal cracking of hydrocarbons and oxygen transfer reaction mediated by FO. Incorporation of FO successfully created porous structure in the produced biochar. The adsorption tests revealed that the biochar exhibited bi-functional capability to remove both positively charged Cd(II) and Ni(II), and negatively charged Sb(V). The adsorption of Cd(II) and Ni(II) was hardly deteriorated in the multiple adsorption cycles, and the adsorption of Sb(V) was further enhanced through formation of surface ternary complexes. The overall results demonstrated nano Fe(III) oxide is a promising amendment material in CO2-assisted pyrolysis of lignocellulosic biomass for enhancing syngas generation and producing functional biochar.

Scale is widely observed in the hydrated lime mine drainage treatment plant of the Daedeok Mine in South Korea. In order to understand the environment in terms of the formation of scale minerals, scale and water were collected from the AMD treatment facility and analyzed. In addition, the saturation index was calculated based on geochemical modeling to predict the minerals that could be produced in the AMD treatment facility, and the results were then compared with an analysis of onsite scale minerals. Furthermore, the onsite mine drainage was neutralized from pH 3 to pH 9 in the laboratory, and the precipitates produced were identified. The changes in the Ca2+ and SO42− concentrations were also identified over time for each pH. The results of geochemical modeling predicted the possible precipitation of gypsum, anhydrite, and bassanite after AMD neutralization. Scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS) analysis results showed that the main mineral in scale formed at the AMD treatment facility was gypsum, produced by the reaction of SO42− and Ca2+ from lime during AMD. The laboratory neutralization experiment showed that gypsum was produced in all neutralization ranges from pH 3 to pH 9, and the higher the neutralization pH, the greater the amount of gypsum produced. It was demonstrated that simulated amounts of 2 g/L and 7 g/L gypsum at pH 5 and 9 were well matched with the experimental results. Iron (Fe), a major pollutant in the mine drainage system, was rapidly precipitated in the form of iron hydroxides after neutralization. As gypsum is produced slowly and continuously for a long period of time, it results in the growth of scale throughout the flow path. As a method of minimizing gypsum production in the AMD treatment facility using hydrated lime, it is recommended that the facility should be operated at the lowest pH possible, which will also enable the removal of major pollutants, such as iron and aluminum.

광산배수 및 슬러지 내 희토류(REE)의 자원화 가능성 평가를 위하여 REE 분석과 연구 동향을 조사하였다. 석탄 및 셰일에서 총 희토류(TREE) 평균은 각각 268 mg/kg 및 283 mg/kg로 분석되었다. 광산배수의 TREE 농도는 pH 값이 낮은 산성배수에서 높았다. REE/NASE 비는 중간 희토류(MREE)가 부화한 특징을 보였다. 대덕탄광의 광산배수가 pH 8.5로 중화되면서 REE 성분이 <0.1 ppb 이하로 감소하여 슬러지로 농축되었다. 금속광산과 석탄광 슬러지의 평균 THREE 는 290 mg/kg 및 532.6 mg/kg으로 조사되었다. 총 17개소의 슬러지 내 REE의 시장가치는 790,493 U$에 달할 것으로 추정하였다. 문헌 조사 결과 REE 회수 연구는 원수 및 슬러지별 흡착 및 침전법으로 회수하는 연구가 수행중이다. 폐광산이 흩어져 있는 현장을 고려한 REE 회수 시스템으로 개별 AMD 처리시설에서 REE를 1차로 농축하고 산 용출 및 용매추출 공정을 갖춘 시설에서 2차로 고순도 REE를 생산하는 개념이 제시되고 있다.