Gold Extraction Research Articles

Extraction of gold from gravity-flotation concentrates via surfactant and oxidation reagents

The focus of this work is to establish a hydrometallurgical technique for efficiently extracting gold from the aggregated gold-rich concentrate produced by a mining facility in one of Kazakhstan's deposits. The leaching techniques applied to gravity-flotation concentrates include hydrometallurgical gold recovery processes using the surfactant sulfanol and the oxidizing reagent trichloroisocyanuric acid (TCCA). The findings indicate the effectiveness of leaching gravity-flotation concentrates with oxidizing (accelerating) reagents. Gold extraction through cyanidation of the blended concentrate, ground to 89–90% passing 10 µm with TCCA, averaged 84.0%, compared to 65.76–67.8% with conventional direct cyanidation. The advantage of employing chlorine-based oxidants, such as TCCA, in hydrometallurgical processing lies in their applicability in both acidic and alkaline environments, whereas other oxidants are constrained by specific technological conditions. Technical trichloroisocyanuric acid (TCCA), a chlorine-containing oxidizer with the formula C3O3N3Cl3, containing 25–30% calcium hypochlorite as an impurity, proved to be the most effective in enhancing gold leaching techniques. Apart from improving the efficiency of the leaching process, the use of TCCA is economically viable. The wholesale cost of technical TCCA is ~ $700 per ton, significantly lower than many other oxidants commonly used in gold hydrometallurgical production. With its higher active chlorine content, TCCA consumption per ton of gold-bearing raw material is nearly half that of hypochlorite or peroxide. Additionally, TCCA use minimizes the formation of unwanted impurities in both the pulp and the productive solution.

Assessment of Gold and Mercury Losses in an Artisanal Gold Mining Site in Nigeria and Its Implication on the Local Economy and the Environment

The objective of this work was to establish the gold and mercury losses in an artisanal mining deposit (Uke) in Nigeria to convince miners about their inefficiency and suggest changes in their gold extraction practices. Samples of feeds and tailings from five sluice box concentration processes previously ground in hammer mills below 1 mm (P80 = 0.5 mm) were systematically sampled every 15 min. for 4 h and sent for gold analyses by a fire assay and intensive cyanidation. Dry grain size analyses of primary and amalgamation tailings allowed us to find out in which size fraction gold and mercury are lost. Total mercury losses in sixteen operations were obtained by weighing mercury at the beginning and in all steps of the concentrates’ amalgamation. After analyses, the average gold grade in the feed resulted in 3.80 ± 1.52 ppm (two standard deviations). The gold recovery was 29.24 ± 13.24%, which is low due to a lack of liberation of the fine gold particles from the gangue (silicates). Finer grinding would be necessary. The mercury balance revealed that 42% of the mercury added is lost, in which 26% involves tailings and 16% evaporated. The HgLost-to-AuProduced ratio was found to be 3.35 ± 9.46, which is exceedingly high for this type of amalgamation process that should have this ratio around 1. One reason is the excessive amount of mercury in the amalgams, 76.5 ± 38.12%, when the normal is around 40%–50%. Mercury lost by evaporation in open bonfires is clearly contaminating amalgamation operators (usually children), neighbours, and the environment. The Hg-contaminated tailings and primary tailings are sold to local cyanidation plants, and this can form toxic soluble Hg(CN)2 in the process. The results of this research were brought to the attention of the miners and other stakeholders, including the regulatory agencies of the government. The % gold recovery by amalgamation was established in this study, but if this process recovers 50 to 60% of the liberated gold particles in a concentrate and 30% of gold was recovered in the sluice boxes, then the total gold recovery should be between 15 and 20; i.e., 80 to 85% of gold mined is lost. On average, an operation produces 8.26 g of gold/month, which is split to six miners, representing USD 69/month/miner or USD 2.3/day. It was discussed with miners, authorities, and community members (in particular female miners) how to avoid exposure to mercury, how to improve gold recovery without mercury, and the health and environmental effects of this pollutant.

2D Electrodes From Functionalized Graphene for Rapid Electrochemical Gold Extraction and Reduction From Electronic Waste.

Electronic waste (e-waste) contains substantial quantities of valuable precious metals, particularly gold (Au). However, inefficient metal recovery leads to these precious metals being discarded in landfills, causing significant water and environmental contamination. This study introduces a two-dimensional (2D) electrode with a layered graphene oxide membrane functionalized by chitosan (GO/CS). The GO/CS membrane acts as an ion-selective layer and demonstrates capabilities in the electrochemical extraction and reduction of Au ions. The multiple functional groups of GO and CS offer high cooperativity in ion extraction and reduction, achieving 95wt.% extraction efficiency within 10min. The simultaneous extraction and electrocatalytic reduction of Au ions within the membrane leads to the formation of ready-to-use metallic Au forms such as chips and sensors. Such an approach eliminates the processing steps required to convert extracted gold into functional products, reducing time, cost, and energy. This direct formation of usable Au components enhances the efficiency of the recovery process, making it economically viable and environmentally sustainable. The gold mining market is projected to be valued at $270 billion by 2032, with the recycling segment reaching $10.8 billion, highlighting the substantial benefits and economic potential of efficient e-waste recycling technologies.

Electrochemical Deterioration of a Gold Thin Film in Bicarbonate Solution: Correlative Optical, Nano-Mechanical, and Chemical Considerations.

The electrochemical dissolution of metals in liquid electrolytes is of great concern for various electrochemical technologies. However, it is also the focus for boosting metal recovery processes, e.g., from electronic wastes, one of which is the extraction of gold (Au) using eco-friendly electrolytes. To shed more light on the possibility and improvement of such metal leaching, this work presents the investigation of electrochemical deterioration of a Au nanofilm coated on a silicon (Si) support─ubiquitous materials in electronic components─in aqueous potassium bicarbonate (KHCO3) electrolyte, a solution widely used in food products. In addition to the time-dependent in situ Raman spectra revealing the reduced reflectivity of Au associated with its molecular degradation, the significant role of the electric double layer (EDL) at the metal/electrolyte interface is also indicated. Analyzing surface adhesion maps and force-distance spectra acquired using atomic force microscopy and spectroscopy (AFM/AFS), metal degradation is related to nanoscale worm-shaped reconstructed surface features that act as local sites of reduced refractive index. Complemented by the non-negligible fraction of K observed on the treated Au surfaces using scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), an electrochemical framework of metal degradation is proposed, depicting the electric-field-induced transport of K+ and H+ ions toward the Au surface regardless of bias polarity and implying the formation of ternary gold hydrides. The consideration of faradic current in the EDL circuit also suggests the occurrence of ternary gold oxides. Such determination is reinforced by the attributability of the polar and electrostatic characteristics of the worm-like features to residual negatively charged anionic clusters of the hydrides and the oxides. The analysis process and the new understanding of metal degradation provide a potential route for inspecting other metal/solution systems.

Electrochemical activation of periodate with graphite electrodes for degradation of high concentrations of thiocyanogen (SCN−) in mineral processing tail liquid

Cyanide has been widely used in gold extraction due to its cost-effectiveness, high selectivity and recovery. Regrettably, its wide application also leads to the presence of a large amount of thiocyanogen (SCN−) in the tail liquid of mineral processing plants, which affects the quality of the effluent water, and thus poses a threat to the ecological environment and human health. This paper investigates the degradation of high concentration of SCN− in water using electrochemical oxidation/periodate (E-GP/PI) system. A degradation rate of 90.25 % of SCN− was achieved by optimising various operating parameters. The effects of organic matter and typical heavy metal ion concentrations on the degradation of SCN− were investigated, and it was found that Cu2+ was able to promote the degradation of SCN− through the formation of stable complexes with SCN−, which enhanced the degradation rate to 96.48 %. However, the presence of Octadecyltrimethylammonium bromide (OTAB) and butylxanthin hindered the degradation process, where 500 mg/L of OTAB reduced the degradation rate of SCN− to 80.88 %, while 100 mg/L of butylxanthin reduced the degradation rate to 78.66 %. On this basis, experiments were carried out using real wastewater samples and SCN− degradation efficiencies of about 90 % were obtained. Afterwards, through electron paramagnetic resonance analysis, free radical burst, ion chromatograph and other research techniques, IO3 and O2– were obtained as the main drivers of SCN− degradation and SCN− degradation pathways were elucidated. Finally, the E-GP/PI system was shown to be effective in reducing the ecotoxicity of SCN− by increasing the 24-h LC50 from 12.5 % to 48.5 % in a toxicity test with daphnia. This study provides a new idea for the green and efficient treatment of SCN− rich beneficiation tail liquid.

Prediction, modeling, and optimization studies of eco-friendly gold extraction using alpha-cyclodextrin and the RSM and CCD methods

In the Democratic Republic of the Congo, gold extraction from ore in South Kivu utilized alpha-cyclodextrin (α-CD) as an eco-friendly method to replace harmful methods. Analysis of variance and response surface methodology were employed for prediction, modeling, and optimization studies. Atomic absorption spectroscopy revealed a 0.06% gold content in a randomly taken ore sample. Leaching with modified aqua regia was optimized with the following parameters: 7.27 h, 50 g/L HBr concentration, pH 1, and 200 rpm stirring speed, resulting in 98.5% removal. Neutralization tests with potassium hydroxide (KOH) followed leaching to prepare the solution medium with appropriate pH for extraction test, by varying parameters such as time, KOH concentration, and pH. Following neutralization, extraction tests with α-CD were carried out and optimized with the following parameters: 40 min, α-CD concentration of 11.6166 g/L, and a pH of 5, resulting in a percent removal of 98.9%. α-CD’s eco-friendly nature, cost-effectiveness, and high percent removal make it a promising and sustainable alternative for gold recovery, appealing to the mining industry.

Bromic acid-thiourea synergistic leaching of sulfide gold ore

Abstract Bromate–thiourea coordinated leaching of gold sulfide ore for gold sulfide ore as leaching object. The effects of leaching reagent, stirring speed, and leaching time on gold leaching were investigated in this article. The results showed that the optimum leaching conditions were potassium bromate 0.1 M, thiourea 0.6 g·L−1, hydrochloric acid 0.2 M, agitation speed 250 rpm, ratio of liquid to solid 4, and leaching time 10 min. Under these conditions, high efficiency and rapid leaching of gold can be achieved, and reagent consumption is reduced. The research results have theoretical and practical significance for expanding new green gold extraction technology.

Comparison of the Reactivity for the Solvent Extraction of Gold(iii) from Concentrated HCl Solutions Among D2EHPA, PC 88A, and Cyanex 272

ABSTRACT In this study, the chemical reactivity of three organophosphorus acidic extractants (D2EHPA, PC 88A, and Cyanex 272) was compared for the extraction of the anionic gold(III) complex, AuCl4 −, from the concentrated hydrochloric acid solutions. The extraction behavior was examined by varying the hydrochloric acid concentration from 1 to 9 M. Among the three extractants, only Cyanex 272 showed significant efficiency in extracting Au(III) with the extraction percentage was proportional to hydrochloric acid concentration. In contrast, the extraction of Au(III) by D2EHPA and PC 88A was not significant. FT-IR spectra analysis indicated that the P=O bond in Cyanex 272 weakened after extraction, suggesting its involvement in the process. Based on the structural differences between the extractants and the observed dependence of gold(III) extraction on the hydrochloric acid concentration, a nucleophilic addition reaction was proposed as the extraction mechanism. Specifically, the phosphoryl oxygen of protonated Cyanex 272 likely forms a coordinate bond with the gold ion in AuCl4 −, facilitating its extraction. This mechanism was supported by both extraction and spectroscopic data, making Cyanex 272 a promising candidate for the selective extraction of Au(III) from highly acidic solutions. The findings offer insights into the extraction of metal ions using organophosphorus extractants in highly acidic environments.

Post-synthetic modification of a MOF via Continuous Flow Methods for Gold E-Waste Recycling.

This study pioneers the use of continuous flow methods to modify the nanoporous metal-organic framework Fe-BTC (MIL-100(Fe)) with redox-active poly-p-phenylenediamine (PpPDA). The Fe-BTC/PpPDA composite, known for its gold extraction capabilities, was synthesized in continuous flow on a 250 g scale. Fe-BTC/PpPDA was then tested in eight industrial leachates (e.g., cyanide, thiourea, aqua regia) exhibiting varying effectiveness, pH, and gold speciation, which led to significant differences in the composite's performance for gold extraction. The composite performed best in solutions containing [AuCl4]- species. Structured into spherical beads using a novel continuous flow microdroplet technique, these adsorbents were tested for gold recovery from real e-waste solutions in a breakthrough epemriment. They achieved a capacity of ~600 mg of gold per gram before breakthrough and ~900 mg per gram at a 60% recovery rate. Selectivity ratios for Au/Ni, Au/Co, and Au/Fe were 972, 262, and 193, respectively. In situ X-ray absorption near edge spectroscopy (XANES) provided evidence of the reduction of Au³⁺ to Au⁰, facilitated by the redox-active oligomers. Outperforming several commercial resins, Fe-BTC/PpPDA shows great promise for scalable, selective metal recovery from waste streams. This study highlights the potential of MOF/polymer composites and continuous flow methods for large-scale production.

Additional extraction of gold in grinding cycles and classifcation of copper-zinc ore of a pyrite deposit in gravity-centrifugal feld

Additional extraction of gold in grinding cycles and classifcation of copper-zinc ore of a pyrite deposit in gravity-centrifugal feld

Combined study of Au-bearing arsenopyrite of orogenic gold deposits (NE Asia): High resolution 3D X-ray computed tomography, LA-ICP-MS, and EMPA data

The distribution of gold in small acicular arsenopyrite of a pyrite-arsenopyrite association from Suzdal (Eastern Kazakhstan), Olympiada (Yenisei Ridge, Russia) and large pseudorhombic arsenopyrite crystals from Bazovskoe (Yakutia, Russia) orogenic-type deposits were investigated. On orogenic gold deposits in NE Asia, occurring mainly in black shales, two productive stages of ore deposition are distinguished, which correspond to two morphological varieties of arsenopyrite. At the early stage, fine-grained acicular-prismatic arsenopyrite with invisible gold was deposited; at the late stage, tabular arsenopyrite in association with free visible gold was formed. The samples of gold-bearing arsenopyrite were analyzed using Scanning Electron Microscopy, Electron Microprobe Analyses, Atomic Absorption and Laser Ablation Inductively Coupled Plasma Mass Spectrometry in combination with High Resolution 3D X-ray Computed Tomography (HRXCT). HRXCT does not destroy the studied mineral during the investigation. That technique permits to do an estimation of the amount of gold inclusions in minerals or host rocks and draw reasonable conclusions about the gold content of the ores, to study in detail the distribution patterns of metal inclusions (associated with certain minerals, cracks, crystal growth faces, etc.) and to determine the form of the gold. It can be used to understanding of the genesis of productive mineral associations, and to developing optimal technological schemes for gold extraction.

IMPLICATIONS AND GEOTECHNOLOGICAL PROPOSITIONS FOR THE YANOMAMI INDIGENOUS PEOPLES DUE TO ILLEGAL EXPLORATION OF GOLD MININGS

The 1988 Federal Constitution recognizes the territorial and cultural rights of the Yanomami indigenous peoples, guaranteeing the demarcation of their lands and respect for their traditional ways of life. But these rights have been violated due to frequent threats to these people, by large economic interests, such as mining and deforestation. To achieve this article, it was necessary to consult specific studies of the Yanomami, collection of primary data. Georeferencing of areas that presented land use systems and natural resources was also carried out, the data was processed to generate thematic maps using the Arcgis 10.5 and Qgis 3.28.14 based on images from LANDSAT satellites. The results indicate that the impacts of illegal gold mining in Yanomami lands are devastating, exploration areas are increasing annually, mercury, used in the gold extraction process, leads to contamination of water courses, compromising sources of drinking water and the water resources necessary for survival. It is concluded that it is essential to implement more rigorous public policies, in addition to strengthening supervision and the application of strong environmental laws to combat illegal mining and with global awareness of the importance of protecting indigenous territories, as well as promoting economic alternatives. sustainable activities that respect the traditional way of life of the Yanomami and preserve the environment.

Efficient and sustainable recovery of Au(I) from thiosulfate solution by tri-n-butylphosphine functionalized chitosan microspheres with abundant pores

Thiosulfate as a green and environmentally friendly lixiviant has received great attention in the field of gold extraction. However, the problem of gold ion recovery in thiosulfate gold leaching solution has hindered the large-scale application of this technology. Here, tri-n-butylphosphine (TBUP) was used as a functional monomer to prepare an adsorbent (CTS-TBUP) with abundant pores through the ion crosslinking reaction of chitosan, which was used to recover Au(I) from Au[(S2O3)2]3− solution with high efficiency and large capacity. CTS-TBUP exhibited good potential for industrial applications with a gold loading capacity of 46.34 mg/g. CTS-TBUP exhibited a similar gold recovery performance for all pH ranges from 6 to 11, and the adsorption process of Au(I) on CTS-TBUP was well described by pseudo-second-order kinetics and Langmuir isothermal model. The mechanism by which CTS-TBUP adsorbs gold ions involves ligand exchange between TBUP and Au[(S2O3)2]3−. In addition, Au(I) on CTS-TBUP will be reduced to elemental gold by TBUP in CTS-TBUP. The mechanism of Au(I) adsorption by CTS-TBUP was also confirmed by density functional theory calculations, and confirmed the rationality of forming a complex with a coordination ratio of 2:1 between TBUP and Au(I) at the theoretical level. CTS-TBUP has a good affinity for gold ions in thiosulfate solution, which provides a new idea for the preparation of gold adsorbent.

Penerapan Metode Enhanced Phytoremediation pada Lahan Bekas Tambang Emas Desa Tirta Kencana Kecamatan Bengkayang

Community gold mining activities using the amalgamation method cause soil pollution due to the use of mercury (Hg) to extract gold content which causes a decrease in soil quality and environmental damage. Enhanced phytoremediation is a method that can be applied to remove mercury levels with using the Cyperus kyllingia plant and adding supporting elements in the form of bacterial isolates that are resistant to mercury. This research aimed to determine the effectiveness of Cyperus kyllingia plants and bacterial isolates for removing mercury levels in mercury-contaminated soil, as well as observing the bacterial population and plant morphology during the research. Based on the research results, it is known that the best efficiency value for removing mercury levels is found in phytoremediation with the addition of bacterial isolates, namely 86.88%. The largest bacterial population was found in the phytoremediation reactor with the addition of bacterial isolates, namely 73.3 × 106 CFU/mL. The mercury content in polluted soil causes changes in plant morphology, namely the color of green plants changes to yellow, but plants can reproduce as indicated by an increase in the number of leaves and plant stems

Elevated total mercury (THg) levels in water sources under the influence of artisanal and small-scale gold mining (ASGM) in Tanzania.

This study investigated the presence and distribution of mercury in water bodies under the influence of artisanal and small-scale mining (ASGM) activities in Tanzania, which continue to predominantly rely on mercury for gold extraction. Various water bodies available for domestic and animal use in mining communities were sampled from surface water sources in ASGM settlements during the rainy and dry seasons. Water samples were analysed using cold vapour atomic fluorescence spectrophotometer (CVAFS). The results indicate that most of water sources had THg levels above the WHO guideline of 1.0µg/L (1000ng/L) for safe drinking water. The levels were significantly higher during the wet season ranging from 3.4 to 96.3µg/L, whereas the range was from 0.84 to 2.12µg/L during the dry period. The higher THg values during the wet season are likely a result of increased lateral transport (e.g. via enhanced runoff) and physical properties of the waterways. Transportation and resuspension of matrix-bound mercury from surface soils and inflow of contaminated water from unprotected tailings were also observed to be potential means of lateral mercury transport. The lowest concentrations (0.846µg/L) were observed in water samples from the Mabubi River, upstream of a mining village. Downstream of the mining village in the same river, higher concentrations were observed in the Nungwe Bay region of Lake Victoria. In other surveyed mining settlements where there were no nearby rivers, pool water indicated high concentrations of THg, including levels above thresholds for safe human use. Immediate stringent measures are needed in order to ensure human and animal safety at ASGM mining settlements. Future investigation is suggested to focus on the distribution of mercury in different media, assessing the prevalence of different mercury species, and investigating the influence of weather and hydrological conditions on the impacts of mercury to organisms as part of the strategies to mitigate mercury pollution.

Graphene/chitosan nanoreactors for ultrafast and precise recovery and catalytic conversion of gold from electronic waste

The extraction of gold (Au) from electronic waste (e-waste) has both environmental impact and inherent value. Improper e-waste disposal poses environmental and health risks, entailing substantial remediation and healthcare costs. Large efforts are applied for the recovery of Au from e-waste using complex processes which include the dissolution of Au, its adsorption in an ionic state and succeeding reduction to metallic Au. These processes themselves being complex and utilizing harsh chemicals contribute to the environmental impact of e-waste. Here, we present an approach for the simultaneous recovery and reduction of Au3+ and Au+ ions from e-waste to produce solid Au0 forms, thus skipping several technological steps. We develop a nanoscale cross-dimensional composite material via self-assembly of two-dimensional graphene oxide and one-dimensional chitosan macromolecules, capable of acting simultaneously as a scavenger of gold ions and as a reducing agent. Such multidimensional architecture doesn't require to apply any voltage for Au adsorption and reduction and solely relies on the chemisorption kinetics of Au ions in the heterogeneous GO/CS nanoconfinements and their chemical reduction on multiple binding sites. The cooperative phenomena in ionic absorption are responsible for the extremely high efficiency of gold extraction. The extraction capacity reaches 16.8 g/g for Au3+ and 6.2 g/g for Au+, which is ten times larger than any existing gold adsorbents can propose. The efficiency is above 99.5 wt.% (current limit is 75 wt.%) and extraction ability is down to very low concentrations of 3 ppm.

Technology, capital, and sustainability: Frontiers in just transitions for African mining

Transitions towards sustainability are crucial in the natural resource sector in Africa, particularly in artisanal and small-scale gold mining (ASGM). This sector is notably characterized by the extensive use of mercury for gold extraction, which poses significant risks to both human health and ecosystems. This study focuses on Tanzania, where international incentives to reduce mercury have led the state to promote alternative methods and scale up production primarily through cyanide leaching—a more mechanized gold extraction technique.This article examines the implementation of these strategies, identifies the barriers hindering this transition, and explores the resulting inequalities. We employ a mixed methods approach, combining surveys, semi-structured interviews, and participant observation. We adopt the Sustainability and Just Transitions frameworks for the Global South, arguing that applying an in-depth relational approach to the interactions between actors and technologies can illuminate the persistence of environmentally unsustainable practices within the local context. In conclusion, we advocate for international strategies aimed at the Global South to consider the how promoting the eradication of environmentally unsustainable practices can affect livelihood creation mechanisms.

Antioxidant and anti-inflammatory activity of gold nanoparticles synthesized employing fruit peel extract of Citrus sinensis L.Osbeck

Abstract Nanoparticle biosynthesis has attained a lot of attention because of its cost-efficiency and eco-friendly process. Only limited studies are available which explain the interrelationship between physical parameters (pH, gold concentration, extract concentration, and temperature) and biological synthesis mechanism. The goal of this study was to predict the antioxidant as well as anti-inflammatory activity of biosynthesized gold nanoparticles utilizing Citrus sinensis peel extract. The initial colour shift from yellow to ruby red served as proof that nanoparticles had been successfully synthesized. The nanoparticles that were synthesized underwent various characterization techniques such as AFM (Atomic Force Microscope), FTIR (Fourier Transform Infrared Spectroscopy), FESEM (Field Emission Scanning Electron Microscope), XRD (X-Ray Diffraction), and UV–vis spectroscopy to examine their properties. Further, the synthesis method was optimized for different pH, various gold concentrations, extract concentrations, and temperatures. The nanoparticles displayed good activity as a powerful antioxidant and anti-inflammatory agent. Advanced studies are necessary to explore their therapeutic property.

Efficient and selective extraction of gold from acidic leaching solutions using novel guanidinium ionic liquid

As gold is a non-renewable resource, it holds both economic and environmental importance to enhance the recycling of precious metal waste from secondary resources. Herein, a guanidine salt ionic liquid ([DIETMG][NTf2]) with low water solubility and viscosity was synthesized by molecular design of guanidine salt ionic liquid with good biocompatibility and biodegradability, and a solvent-free system of [DIETMG][NTf2]-water was constructed to extract Au(Ⅲ). The findings reveal that the extraction efficiency of Au(Ⅲ) can reach 97.57 % under optimal extraction conditions. Further thermodynamic and kinetic studies revealed that the reaction process is spontaneous and exothermic, with the extraction rate being primarily controlled by interfacial chemical reactions. The system demonstrates remarkable selectivity for Au(Ⅲ) in solutions containing a mix of various metal ions. Finally, ascorbic acid (Vc) was employed as a stripping agent to obtain gold at room temperature. After 8 cycles, [DIETMG][NTf2] still achieved a 90% extraction efficiency. This study provides a new idea and method for recovery of gold from secondary resources.

Mercury Reduction using Isolates of Indigenous Fungi with Qualitative and Quantitative Methods

Abstract Illegal gold extraction in Indonesia, particularly in Kedungbanteng, Banyumas Regency, Central Java, causes mercury pollution in rivers and poses risks to health and ecosystems. Bioremediation, using fungi, can help cleaning up mercury pollution. This is achieved through utilizing these fungi in ways that align with emerging technologies. The study used fungi isolated from gold mining sludge waste in Kedungbanteng, Banyumas Regency that have the potential to reduce mercury (Hg). Its followed by assesing the effectiveness of fungal isolates to reduce mercury (Hg) both qualitatively and quantitatively. The study found that certain indigenous fungi from the gold mine waste in Kedungbanteng, Banyumas, have the potential to reduce mercury levels. These fungi belong to the Aspergillus (isolate A2), Penicillium (isolates A1, A4, and A5), and Basidiomycota phylum (isolate A3). Isolates A3, A4, and A5 were the three most adaptable fungi in media containing high levels of Hg. Qualitative test results show isolates A3, A4, A5 formed a yellow and white precipitate. Each of them can reduce mercury levels by 46%; 32%; 48%, respectively. Isolate A3 showed the highest average reduction in mercury levels in both fungal biomass and surrounding media. The finding in this study is that there is a relationship between the results of the qualitative test and the quantitative test. The correspondence between the two types of tests shows that the qualitative test has a significant representation of the quantitative measurement of Hg values in the tested media. Penicillium sp. isolates A5 has the potential to be used as an eco-friendly bioremediation agent as the best solution to pollution. issues.