Gold Ore Research Articles

The effect of phytoremediation on the reduction of mercury-contaminated water from gold processing using water kale (Ipomoea aquatica Forsk)

Gold ore processing is carried out by amalgamation techniques where mercury (Hg) is used as a medium to bind gold which results in water pollution around the processing area, so it is necessary to remediate water. One way in managing mercury-contaminated water is phytoremediation of the use of water kale (ipomoea aquatica forsk) and to help the phytoremediation process, ingredients are needed that can help the growth of water kale in increasing the absorption of Hg concentrations, namely the addition of liquid NPK fertilizer. This study aims to analyze water kale without liquid NPK fertilizer, and use liquid NPK fertilizer against water kale in reducing the concentration of Hg, pH and TSS metals in water. This study used an experimental method with an experimental box (container) consisting of 4 treatments, then an Analysis of Variance (ANOVA) test of 5% and Duncan Multiple Rang Test were carried out. The results showed that liquid NPK fertilizer had an influence on reducing the concentration of Hg, pH and TSS in water. Based on the results of experiments using liquid NPK fertilizer, the best treatment results were obtained in mercury absorption by water kale and reducing Hg concentration in water, namely treatment D (contaminated water + water kale + liquid NPK fertilizer) on the 14th day, as evidenced by a decrease in Hg concentration in water by 0.56 mg / l to 0.00486 mg / l, pH 10.1 to 6.86 and TSS 1695 mg / l to 1 mg / l and an increase in nitrate levels, Phosphate and potassium in water can accelerate absorption by water kale.

Characterizing low-grade refractory gold ores using automated mineralogy coupled with LA ICP-MS

Researchers have made notable progress in quantifying refractory components causing gold losses in traditional extraction methods. The potential for improving gold recoveries lies in targeted re-treatment of the 'invisible' gold fraction hosted within various ore minerals, even at low concentrations. This study presents a methodology for analysing the refractory components that cause gold losses in traditional extraction methods. The approach utilizes automated mineralogical techniques in conjunction with in-situ laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) to characterize low-grade refractory ores and assess gold deportment. The methodology combines pre-concentration gravity separation, traditional chemical and mineral techniques, and LA ICP-MS to generate comprehensive datasets. To demonstrate the practical application of the methodology, a case study was conducted on historical tailings material from Witwatersrand's Evander Goldfield in South Africa. The case study aimed to determine the mineralogical distribution of gold that cannot be extracted through cyanidation. The results indicated that invisible gold is primarily hosted in pyrite (with an average concentration of 10.21 ppm representing 32 % of total gold), other sulphides (with an average concentration of 1.29 ppm representing 0.42 % of total gold), and oxides (with an average concentration of 0.50 ppm representing 1 % of total gold). The remaining gold is present in discrete fine cyanide amenable phases (with 28 % deportment) and silicate-hosted phases (with 39 % deportment). Environmental monitoring of the Witwatersrand tailings material revealed a net “acid-producing” nature, with high concentrations of heavy metals (such as As, Cu, Pb, Mn, Hg, and Ni) associated with sulphides (with over 78 % deportment). The deportment information obtained through this approach can optimize ore processing strategies and provide valuable insights for future remediation plans. By characterizing the refractory components causing gold losses and understanding the distribution of gold within the ore, this methodology offers the potential to enhance gold recovery and improve the efficiency of ore processing operations.

Ore-forming material sources of the Pakbeng gold deposit, Laos: Evidence from fluid inclusions, H-O-S isotopes, and trace elements

The Pakbeng gold deposit, located at the junction of the eastern Tethys and western Pacific tectonic domains, is part of the Phôngsali-Luang Prabang-Sayaboury polymetallic metallogenic belt. Its gold ore bodies are predominantly governed by fault structures, being vein-like and short-axis-veined in shape. The Pakbeng gold deposit primarily exhibits two types of mineralized alterations: the quartz-vein type and the schistositized altered rock type. The ore bodies are primarily distributed within cataclastic granites and altered andesite plutons, near their contact zone. The ore-forming process can be divided into four stages: quartz + rutile + pyrite (stage I), quartz + pyrite + coarse-grained arsenopyrite (stage II), quartz + polymetallic sulfides + native gold (stage III), and calcite + quartz (stage IV). Native gold primarily occurs as invisible gold in the quartz and pyrite of stages I and II, and as enclosed, intergranular, and interstitial gold within the quartz, pyrite, and other metal sulfides of stage III. The ore-forming materials of the Pakbeng gold deposit primarily originate from plagioclase granites and altered andesites, as indicated by investigations of gold-bearing quartz fluid inclusions, hydrogen and oxygen isotopes, the trace-element composition of pyrite, and in situ sulfur isotopes. The sulfur in the deposit is mainly derived from metamorphic sources, supplemented by late magmatic sulfur. The ore-forming fluids in the deposit were dominated by metamorphic fluids in the early stage, with magmatic fluids participating in the late stage. While ascending, the temperature of the ore-forming fluids decreased due to fluid boiling and mixing, but their salinity increased slightly. The ore-forming fluids exhibited a consistent decrease in homogenization temperatures from stages I to IV, with salinity initially increasing and then decreasing. This suggests that the ore-forming fluids are low-temperature, medium to low-salinity and low-density fluids.

Gold Migration and Precipitation as Collaurum in Orogenic Gold Deposits: Constrains from Microscopic Gold Particles Observed in the Alteration Zone in Shanggong Gold Ore, Henan, China

Aqueous complexation has long been considered the only viable means of transporting gold to depositional sites in hydrothermal ore-forming systems. Here, we present direct evidence supporting an alternative hypothesis, namely, the transport of gold as colloidal particles. We observed nano-scale gold particles adsorbed on halloysite and micro-scale gold particles in altered rocks by TEM and SEM in the Shanggong orogenic gold deposit. Based on this evidence, we propose a feasible model for the origin of microscopic gold particles in alteration zones. In the early stage of ore-forming fluid, gold may migrate in the form of collaurum, which is maintained by supercritical CO2 and colloidal silica. Low salinity and high pressure are conducive to the stable migration of colloidal gold. When the physicochemical conditions change, some collaurum is precipitated and adsorbed by the clay minerals produced by hydrothermal alteration, and some collaurum undergoes growth and evolves into micro-submicrometer-sized gold particles. This study highlighted the significance of collaurum in the formation of orogenic gold deposits.

Оценка нормирования прибыли и границ горной ренты I и II как экономический метод регулирования горного проекта

Based on the study of empirical economic data obtained during operation of a large-scale gold ore deposit, a model was built to justify the hypothesis about profit rationing, the formation and division of the differential rent I and II. The model identifies the increase in the equity premium as the sum of profit and rent II for investment capital and rent I for the owner of the resources. Boundaries of the capital movement are highlighted for the terms of service agreements with and without risk. The obtained values are attractive for the investment and/or operating side, and the resource owner during the field development. The approach based on profit rationing, assessment and division of the mining rent by types: (1) will help to introduce civil law relations in subsoil use based on service contracts with or without risk; (2) takes into account the value of reserves and resources in their mining and dividing them into ownerships, resources and investment capital; (3) introduces a new approach to attractiveness of deposit mining, both in attracting investment capital and for the operating companies based on a risk-free contract with retention of the ownership of resources with the country of the resource owner; (4) enhances the investment and production attractiveness of deposit mining providing incentives to introduce innovation technologies and improve the efficiency. It is possible to create an economic method for managing and regulating the mining industry of the Kyrgyz Republic based on the proposed approach.

Exploring Non-ammoniacal Thiosulfate Gold Leaching and Limited Gold Recovery from a Refractory Gold Ore Oxidized in Alkaline Pressure Conditions

Exploring Non-ammoniacal Thiosulfate Gold Leaching and Limited Gold Recovery from a Refractory Gold Ore Oxidized in Alkaline Pressure Conditions

AN INVESTIGATION ON THE USE OF T’BOLI GOLD TAILINGS FROM MINDANAO STATE UNIVERSITY – ILIGAN INSTITUTE OF TECHNOLOGY (MSU-IIT) GOLD PILOT PLANT AS TOTAL REPLACEMENT OF FINE AGGREGATES IN CEMENT MORTAR

Gold tailings are waste products produced from the extraction and recovery of gold from its ore. At present, these tailings are in large amounts and are stored in tailings storage facilities, mostly in the form of dams. These gold tailings dams could have serious consequences for the environment and humans if unfortunate events happen. Thus, it is important to utilize these wastes not only to give them value but also to lessen the environmental and human risks they bear. This study investigates the use of gold tailings produced by the Mindanao State University – Iligan Institute of Technology (MSU-IIT) gold pilot plant from the gold ore of T’Boli, South Cotabato, Philippines, as a total replacement of the sand (fine aggregates) component in cement mortar. The chemical compositions of the T’Boli gold tailings were identified using XRF and SEM-EDX analyses. It was found that SiO2, Al2O3, Fe2O3, K2O, and CaO were the major oxide minerals found in the tailings sample. To investigate the effect of the gold tailings on the mechanical property (compressive strength) of the cement mortar, two different formulations of cement and gold tailings (20:80 and 15:85), a controlled formulation with no gold tailings, and two different curing periods (7 and 14 days) were used. The result shows that the formulation of the control sample produces the highest compressive strength of 20.95 MPa at a 14-day curing period. This is followed by the cement mortar in ratios 1:4 and 1:5.7 at a 14-day curing period with a compressive strength of 9.11 MPa and 7.14 MPa, respectively. With these findings, it shows the suitability of T’Boli gold tailings (mining waste) as an alternative to fine aggregates in cement mortar.

AAS and XRD Analysis of Gold Ore Bioflotation Results with Aloe Vera as an Environmentally Friendly Reagent

Flotation is a mineral concentration method that involves floating the minerals so that they can be separated from the gangue by the addition of reagents. The reagents used are chemicals such as frother and collector, which can potentially contaminate the environment. This research explores the potential use of aloe vera as a separating reagent in environmentally friendly gold ore flotation. The feed used consists of 300 grams of gold ore, and the flotation time is set at 15 minutes. XRD analysis is employed to determine the types of minerals contained in the sample, revealing that the sample consists of 97.64% quartz; Enstatite, syn 1.21%; and Clinochlore-1A 1.16%. Atomic Absorption Spectrophotometry (AAS) is the technique used to determine the metal concentration in a sample. AAS analysis indicates an Au concentration in the feed of 3.94 ppm. The Au concentration in the concentrate with the addition of aloe vera extract is 10.57, and in the tailings, it is 0.92, higher than the concentration in the concentrate without the addition of aloe vera extract, which is 10.11, with 1.89 in the tailings. The %recovery from these concentrations with the addition of aloe vera extract is 84.06%, while without the addition of aloe vera extract, it is 63.78%. This study provides evidence that the use of aloe vera in the gold ore flotation process can be a sustainable and environmentally friendly alternative in the effort to improve the separation of valuable minerals from impurities.

The Effect of Aloe Vera Bioreagent as a Frother and Collector in the Gold Ore Flotation Process on Increasing Grade and Recovery

One of the concentration processes in processing sulfide gold ore is the flotation technique which takes advantage of differences in mineral surface properties by adding chemical reagents. The addition of chemical reagents to the flotation process can cause environmental problems. Therefore, efforts are needed to replace chemical reagents with more environmentally friendly materials. In this research, an attempt was made to replace chemical reagents with a commonly found plant extract, namely aloe vera, as a bioreagent. Bioflotation experiments on a laboratory scale were carried out using a Denver flotation cell with an aloe vera reagent as a frother. This gold mineral bioflotation experiment was carried out on a 150 mesh size fraction. The results of increasing concentrate levels by flotation indicate that the aloe vera reagent as a frother is able to produce biosurfactants which replace chemical reagents as a more environmentally friendly biofrother and biocollector. This can be concluded based on flotation experiment data with bioreagent which has been tested showing an Au content value of 10.09 and a recovery of 96.15%, while flotation using chemical reagents shows an Au content value of 10.50 and a recovery of 95.96%. So the use of aloe vera as an environmentally friendly bioreagent in the flotation process releasing low sulfidation gold is more effective than the use of chemical reagents because it is indicated that there is a biosurfactant content in aloe vera.

Geogas prospecting for igneous ore deposits covered by regolith: the Zijinshan high-sulfidation epithermal Cu–Au deposit in the Cathaysia Block

The mining industry faces a challenge due to the scarcity of outcrop or near-surface mineral deposits, necessitating the development of low-cost and efficient prospecting methods to explore through cover. Inductively coupled plasma mass spectrometry has been applied to geological sample analysis, and scientists have gradually improved the method of geogas prospecting. As a result, geogas prospecting has shown promising results in detecting underlying concealed Au, U and Cu–Ni deposits covered by Gobi sand and Quaternary sediments. To verify the effectiveness of this method for exploring underlying concealed mineral deposits developed in igneous covered areas, the Zijinshan high-sulfidation epithermal Cu–Au deposit, a concealed mineral deposit in southeastern China, was selected as the experimental field. Our experiments revealed nanoscale particles composed of Au, Cu–Fe and Cu–other elements in the geogas captured above the ore bodies of the deposit. Furthermore, Cu–nanoscale particles retain the isotopic composition of copper found in both the oxidation zone and deep copper ores. The geogas samples exhibited similar C1-chondrite normalized REE distributions, with REE patterns indicating significant enrichment of LREE relative to HREE and similar (La)N/(Sm)N and (Gd)N/(Yb)N ratios. These characteristics are similar to those of the gold ores, copper ores, altered rock and bedrock near the ore bodies. These findings suggest that deep-penetration geochemical methods using geogas can be a valuable tool for uncovering underlying concealed mineral deposits in igneous covered areas.

Prospects of forward osmosis-based membranes for seawater mining: Economic analysis, limitations and opportunities

Processes for separating solutes from water, including desalination, are based on synthetic membranes using the forward osmosis (FO) technique. The industrial-level success of these membrane techniques has been astounding. Modern desalination membranes, however, cannot extract a single metal ion with precision from a commingled ion solution. Lithium, cobalt, uranium, and other energy-critical elements will soon be in greater demand than they can meet, thus elevating their importance as geopolitical resources. Critical metals can be found in seawater, an essential yet unconventional supply. Gold mining and ore processing are activities of great economic importance. However, they are related to generating extremely polluted effluents containing high concentrations of heavy metals and low pH. The review highlights the most recent design and deployment of FO desalination technologies, their application in sea mining, and the remaining challenges and prospects. This work also highlights the enormous potential of FO sea mining and how it is crucial to optimize the operating parameters, including draw solutions and energy consumption, and raise attention toward the economic aspect and market diffusion of FO sea mining.

A Comparative Analysis of Non-Cyanide and Cyanide Gold Leaching Technologies: Lessons Learned from the Failed CLINN GEM Facility and Promising Results of the REVIVE SSMB Project in Itogon, Benguet

This research paper presents a comparative analysis of a non-cyanide gold leaching technologies implemented in the small-scale mining community of Itogon Benguet against a potential gold recovery method with Free Cyanide decontamination and Sodium Cyanide recovery system. The study evaluates the failed CLINN GEM facility and the successful REVIVE SSMB project, focusing on technology readiness and acceptance, operational efficiency, and community engagement. The results demonstrate that the failure of the CLINN GEM facility was attributed to its low community acceptance, high operating costs, and complexity, hindering its practicality and scalability. In contrast, the REVIVE SSMB project achieved exceptional results through an alternative gold ore leaching process using Cyanidation CIP method, driven by strong community engagement, cost-effectiveness, sustainable wastewater/tailings discharge management system and simplified operation approach even for the recovery of gold from complex and low-grade Au ore from the locality. For a viability assessment, a stochastic model for the technology feasibility and project optional valuation under diverse uncertainty consideration for community adoption and expansion presentable to potential investors or for the option right to accept and manage the technology as demonstrated. This research simulated the viability of the REVIVE SSMB approach with a high predictability using Monte Carlo Model through Real Option Analysis; and under the worst-case scenario at 50th percentile (median) 74.53% recovery was achieved. Repeatedly with a similar 50th percentile simulation under an optimized condition with pulp density of 44- 50% and 3kg per ton of activated carbon loading during flotation yielded a gold recovery of 91%. Hence, it is arguably viable, coupling with the 98 to 99% free cyanide decontamination rate and the 55% NaCN recovery successful discharge management system under the REVIVE SSMB 6 months project model.

Pretreatment of refractory gold ore by curing with concentrated sulfuric acid

Pretreatment of refractory gold ore by curing with concentrated sulfuric acid

Mineralurgical and Environmental Characterization of the Mine Tailings of the IOCG Mine of Guelb Moghrein, Akjoujt, Mauritania

Since 2004, the processing of the iron oxide–copper–gold (IOCG) ore of Guelb Moghrein, Akjoujt, Mauritania, has resulted in the generation of approximately 40 million tons of mine tailings. The storage of these tailings poses significant environmental challenges particularly to surface and underground water resources. To address this issue, we propose an approach involving both mineralurgical and environmental characterization. Our mineralogical analysis reveals that the TSF tailings consist of sulfides and iron oxides associated with a silico-carbonated matrix. This mineralogical analysis also shows that the TSF tailings consist of secondary minerals, resulting from sulfides oxidation. Furthermore, our findings indicate that the chemical analysis of the TSF tailings contains potential toxic elements (PTEs) such as Cu, As, Co, Ni, Sb, and Se. Regarding the environmental characterization of the tailings, conducted through acid-based accounting (ABA) static tests, we demonstrate that leaching from the tailings generates a contaminated neutral drainage (CND).

Effect of Power and Exposure Time on the Microwave-Assisted Roasting of Refractory Gold Ore

Reserves of high-grade gold ore worldwide are decreasing, and some industries have started processing refractory gold ore. Refractory gold ore contains sulfide minerals such as pyrite (FeS2), chalcopyrite (CuFeS2), galena (PbS), and sphalerite (ZnS). Gold in refractory ores occurs as fine-size gold-bearing sulfide minerals. In this study, the microwave-assisted roasting method has been investigated as a pretreatment for a refractory gold ore. This method can provide rapid heating radiation, cause micro-cracks, and trigger the decomposition of sulfide minerals. The presence of additive helps in the oxidation of sulfide minerals. The microwave-assisted roasting was carried out using variations in microwave power and time. Microwave power between 300 - 600 watts significantly affected the increase in roasting temperature and weight loss of refractory gold ore. The highest temperature reached 567°C in roasting at 800 watts for 30 minutes. The optimum condition for microwave roasting was achieved at 400 watts of power with a roasting time of 30 minutes. Metals extraction of Cu, Zn, Pb, and Fe reached 97.2%, 82.7%, 16.1%, and 2.1% in water leaching.

Investigating the benefits of using HPGR prior to cyanidation of low grade gold ore

AbstractIt is known that the cracked structure of the particles has positive effects in leaching processes. In this respect, high pressure grinding rolls (HPGR) provides some advantages such as increasing leaching efficiency and reducing leaching time by creating more cracked particles compared to other crushers. Although there are studies on the advantages of HPGR on different ores, these have not been fully demonstrated in low grade gold ores, and leaching kinetics have not been examined in detail in the studies conducted in this context. In this study, first of all, crack formation in a low grade gold ore by crushing with HPGR and jaw crusher was investigated. Then, bottle roll tests were performed in different size fractions and different cyanide concentrations along with column leaching of the pelletized ore in a single test condition. As a result of the studies, it was determined that 2–3 times more cracked particles were formed in HPGR depending on the particle size. It was shown that the modified Kelsall model explains the kinetics better than other kinetic models tested. In summary, it was revealed that maximum gold extractions are almost same for HPGR and jaw crushers. However, the fast dissolution kinetic constant was found to be around 25% higher for HPGR than for the jaw crusher in bottle roll tests while this ratio was approximately 30% higher in column leaching tests, suggesting a distinct influence of the crushing method on the dissolution kinetics.

SODIUM DITHIONITE AS A PYRITE DEPRESSANT IN GOLD ORE FLOTATION

Sodium dithionite (Na2S2O4) is a widely used reducing agent to control pulp potential (Eh) and pyrite depressant in sulfide ore flotation. In this study, the pyrite depressant effect of sodium dithionite on gold ore flotation was investigated at pH 8 and pH 10.5 comparatively in terms of gold, chalcopyrite, and pyrite recoveries and grades. The presence of sodium dithionite resulted in a drop of approximately 50–70 mV in the Eh values, regardless of the studied pH values, confirming the reducing effect of sodium dithionite. The effects of sodium dithionite on gold and chalcopyrite grades and recoveries were quite limited, especially at pH 10.5. At pH 8, the utilization of sodium dithionite slightly decreased gold and chalcopyrite recovery and grades, while the decrease in pyrite recovery and grades was remarkable. Both pyrite recovery and grade were reduced from 79.5% to 54.7% and 15.3% to 10.7% by the utilization of sodium dithionite at pH 8. In conclusion, it is considered that the selective flotation of gold and chalcopyrite from pyrite can be achieved at a lower pH accompanied by a slightly reduced Eh by the utilization of sodium dithionite.

Mechanism of synergistic pretreatment with eco-friendly CaO and Na2CO3 to enhance gold leaching efficiency from fine-disseminated gold ores

Efficient pretreatment of fine-disseminated gold ore is a challenge in effective gold extraction due to the invisible occurrence of the most encapsulated gold. In this study, we investigated the mechanism of co-pretreatment with eco-friendly CaO and Na2CO3 to improve gold extraction from fine-disseminated gold ore using element content and valence measurement, phase composition analysis, micromorphology and structure characterization, and thermodynamic calculation. The results indicated that more than 75% of gold was encapsulated in pyrite, quartz and calcite. The gold leaching rate evidently increased with the reagent content and slurry temperature of the pretreatment, reaching a maximum of 86.55% at 60 °C and CaO and Na2CO3 concentrations of 16 and 32 g/L, respectively. At lower concentrations of OH− or CO32−, pyrite oxidation and quartz corrosion were both limited. Interestingly, at higher concentrations of OH− and CO32−, pyrite was ultimately converted to Fe2O3 and SO42− under aerobic conditions; meanwhile, partial dissolution products of quartz reacted with the intermediates of pyrite oxidation, generating a new phase of Fe2SiO4. In addition, the soluble intermediate ferric carbonate complexes, formed by the induction of sufficient CO32−, inhibited the accumulation of the passivation layer on the pyrite surface, resulting in constant oxidation of pyrite. Furthermore, the oxidation of pyrite was the maximum at 60 °C, but limited at 90 °C due to the hindrance of oxidation product coating. As a result, the phase transition of gold-bearing pyrite and quartz could be enhanced by the synergistic pretreatment of CaO and Na2CO3, resulting in an approximately 30% increase in both exposed gold content and gold leaching rate. This research proposes a promising green pretreatment with cost benefits for fine-disseminated gold ore and provides significant insights into phase transition regulation to improve gold leaching.

Radiometric characteristics of some metallic ores and nonmetallic deposits: an example, Wadi Al-Allaqi, South Eastern Desert, Egypt

Hydrothermal alteration processes are connected to many mineral formations, particularly auriferous deposits. In this study, airborne gamma-ray spectrometry (GRS) data and the analysis of radioactive materials (eU, eTh, and K) are applied to search for regions with hydrothermal alteration activity. An example is presented from Wadi Al-Allaqi, South Eastern Desert, Egypt. GRS was used to analyse various radiometric data to address potential mineral deposit areas, to map regions potentially showing metallic ore mineralisation, and to point out new geological mineral resources. The Kd (potassium deviation), “F” parameter and Th-normalisation of the K and eU anomalies were calculated, and locating new exploratory targets in the study area that exhibit high F-parameter, Kd, and K/eTh values was recommended. Additionally, the research region has a few isolated enriched spots of (K). Therefore, GRS data was used to characterise and estimate potential metallic ores, nonmetallic deposits, and gold ore zones associated with the alteration zones. Results show that most of the known mineral deposits and gold occurrences in the area, according to the metallogenic map of Egypt, are located in zones with a ratio value of (0.25–0.30) (K%/(U or Th ppm)) maps which may suggest a moderate degree of alteration. Also, most mineral deposits and gold occurrences are found in intermediate altered zones, or K-enriched sites, with a Kd% of (0.2. The work represents an attempt to map hydrothermal alteration zones associated with mineral deposits in the Wadi Al-Allaqi area. Generally, natural radiation characteristics and attributes suggest criteria that can be used globally for regional mineral exploration.

Outlook for the long-term exploitation and development of the gold mineral resource base in the Russian Federation

The current state of the gold mineral resource base of the Russian Federation is considered. The forecast of the mineral resource base development up to 2040 has been performed. Three scenarios is provided for the gold production until 2040. The need is substantiated to intensify early-stage geological exploration in order to reveal new gold ore objects, to prepare the forecasted resources, and to create the “fund of exploration-deserving objects”.