ABSTRACT This study aimed to determine the current state of gold (Au) prospectivity and the characteristics of gold panned from the Osu area in southwestern Nigeria. Soil, heavy mineral samples, and gold nuggets were collected from artisanal mining pits. Heavy mineral samples were analyzed using scanning electron microscopy (SEM). Trace elemental composition of soil samples was determined using inductively coupled plasma-mass spectrometry. The morphological, mineralogical, and micro-chemical characteristics of gold grains were determined using TESCAN integrated mineral analysis. SEM revealed that the heavy minerals associated with the gold are sub-rounded to sub-angular ilmenite, baddeleyite, quartz, zircon, and staurolite. The Au concentration from the pits ranged 0.1–40.5 ppb, with higher concentrations of 33.3–40.5 ppb observed around 12–15 m and 12.3 ppb around 10–13 m. The Au nuggets varied 10–900 µm and were elongated and sub-angular to rounded, which implies that they were close to their source. The Au grains were composed of 88.3–100% Au and 0–11.7% silver, with ilmenite-rutile, cassiterite, columbite, kaolinite, monazite, chamosite, and iron oxide as accessory minerals. Gold exploration in soils around Osu should target depths of 10–15 m, which are associated with anomalous gold concentrations in this study.

ABSTRACT Cobalt (Co) is a critical metal key to a successful global energy transition. The Democratic Republic of the Congo (DRC) contains more than 50% of the world’s Co reserves, positioning it as a leading source, with an estimated market share of 76% in 2023. However, a non-negligible share of the DRC’s Co originates from artisanal and small-scale mining (ASM), which is highly criticized due to serious ethical and environmental concerns; these concerns negatively impact the perception of DRC mineral extraction. The U.S. Department of Labor has therefore blacklisted DRC Co. This embargo on Co will prevent the DRC from realizing its ambition of using the profits from the exploitation of mineral resources to expand socioeconomic development. This article describes DRC ASM, examines the role it could play in addressing the challenges of the nation’s socioeconomic development, and suggests a procedure to improve the applicability of mining laws and regulations.

ABSTRACT Reaching an informed decision about optimal drill-hole spacing (DHS) is an essential task in geostatistics that adds value to mining projects. The optimal DHS is sensitive to many factors, including inherent geologic characteristics of the deposit, mining and operational parameters or constraints, economic factors, the purpose of the mineral resource estimation, and the metric to be optimized. Final estimates at the grade control (GC) stage of mining are meant to maximize the correct classification of mineable volumes. When considering dedicated GC drilling, DHS optimization for profit balances the cost of estimation uncertainty and the cost of drilling. The drilling amount is optimal when drilling less would incur large estimation costs and drilling more would incur large drilling costs. We developed a DHS framework for regularly spaced drilling aimed at maximizing profit in GC. Each of the steps are described in detail, including sequential Gaussian simulations, resampling, estimation, transfer function customization, mineable limits definition, and final profit calculation. The DHS framework is demonstrated on a realistic data set, followed by a sensitivity analysis to relevant factors. This work establishes a conceptual foundation and provides practical details for developing DHS optimization for final estimates in mining operations with dedicated drilling systems.

ABSTRACT New dynamic models of overwind arresting and crash beam impact of the conveyances of a multi-rope friction winder are developed. These models treat the descending head ropes as axial components with distributed mass and stiffness. Using explicit analytical solutions derived for the crash beam impact model, an example case is analyzed. Compared to a previous model by Greenway that treated the descending ropes as rigid bodies, this analysis predicts significantly lower head rope tensions on both the ascending and descending sides of the winder drum for crash beam impact. The predictions of the new overwind arresting model are compared to two previous models by Hamilton and Greenway for the same example winder. While some variation in the results is apparent, the numerical values are all similar. On the other hand, the time histories of the new model show better correlation with Hamilton’s numerical simulation than with the rigid rope model of Greenway. A wave propagation effect is evident in the new model output as well as in Hamilton’s method. This and the use of a model for a constant force arrestor demonstrate the importance of modeling the flexibility of the descending head ropes—particularly for deep shafts.

ABSTRACT With the depletion of surface mineral reserves, miners are confronted with ever hotter and typically more humid working conditions in deeper mines, which threatens their well-being, safety, and productivity. This study examines thermal comfort parameters affecting workers in subterranean environments. The approach employs the predicted mean vote model based on the ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) thermal sensation scale and employs the classic machine learning techniques of logistic regression, support vector machine (SVM), k-nearest neighbor (KNN), and decision trees. The decision tree model attained the highest level of accuracy (100%), followed closely by KNN (95.08%), SVM (93.85%), and logistic regression (78.69%). The findings suggest that maintaining thermally optimal conditions is crucial to boost miners’ well-being. This can be achieved by enhancing ventilation, providing appropriate clothing, and ensuring regular rest breaks. These actions are essential for minimizing health risks and enhancing productivity.

ABSTRACT During mining, native vegetation, dead organic matter, and soil are stripped from the landscape to accommodate mine infrastructure. Carbon emissions increase in response to rapid land-use change (LUC) because the carbon storage (i.e., in living and dead biomass) capacity of the site is reduced or lost for the life of mine. New and expanding mines need to account for these carbon impacts during net zero planning for their operations. This analysis reviewed LUCs for 85 metal mine sites in Canada in 2001 ± 1 and 2019 ± 1. LUC was estimated using satellite imagery and publicly available operations information. Greenhouse gas emissions were determined based on a Government of Canada accounting method. A total of 27,000 hectares of land were disturbed. The associated 12.6 million tonnes of carbon dioxide equivalent emitted during the study period represented approximately 15% of Scope 1 emissions from hydrocarbon-based fuel consumption at these operations. The impact on the carbon sink estimated for select sites was up to 20% of the carbon emissions from LUCs.

ABSTRACT Increasing demand for various metals, including gold and silver, has initiated a favorable cycle for mining investors. However, mining projects remain risky due to the significant investments required and project-specific technical factors that are subject to geological uncertainty. Specifically, narrow vein mining suffers from a lack of geometrical freedom in the advance of the excavation; therefore, mine planners must compensate by controlling stockpile and blending and metallurgical process variables. Nonetheless, this lack of geometrical freedom makes it possible to link geological uncertainty to dynamic functioning of the process and ultimately to the net present value and internal rate of return. Discrete rate simulation is an effective approach to dynamic mass balancing, in which geometallurgical relationships can be implemented considering geostatistically variable incoming combinations of andesitic and rhyolitic ore in the case of narrow vein Au-Ag mining. The limited geometrical freedom is conducive to a simple mining sequence, easily implemented within a discrete rate simulation that includes a stochastic representation of the narrow vein orebody based on sequential indicator simulation. The resulting tool uses the apparently disadvantageous geometry of narrow veins and is effective at capturing project-specific metallurgical variables within economic prefeasibility and feasibility studies.

ABSTRACT A review of 175 recent Australasian Joint Ore Reserves Committee (JORC), National Instrument 43‐101, and U.S. Securities and Exchange Commission technical reports was conducted to study prevailing practices in mineral resource estimation (MRE), mineral resource classification (MRC), and capping of extreme values workflows in the mining industry. The goal is to discover trends in current practices and examine differences between reporting jurisdictions and deposit types. Ordinary kriging is the predominant MRE method, but inverse distance weighting remains prevalent. Drill hole spacing (DHS) and search neighborhood are the most common criteria used for MRC, while statistical metrics such as kriging variance, slope of regression, and confidence intervals are rarely used. MRC method selection depends on deposit type, commodity type, drilling pattern, variogram range, and nugget effect. JORC reports often use DHS for MRC, while National Instrument 43-101 reports show more diversity. A proposed data-driven decision tree classifier predicts the most commonly used MRE, MRC, and capping strategies with accuracies of 82.6%, 83.6%, and 84.7%, respectively. This model is not intended to replace a practitioner’s method choice but allows them to quickly assess what others have considered for similar deposits. Note that we are careful in this work to avoid judgments of the “best” workflow: our goal is to highlight what is being done in the industry.

ABSTRACT State equity participation has been used by several countries to obtain additional returns from mining projects. Although control may actually be the motivation, the financial rewards accompanying share ownership seem to be important as well. Ghana has imposed a non-dilutionary free carried interest equity arrangement on the mining industry whereby the entire financial burden for developing the mining project rests on the private investor without precluding the state from enjoying all the economic benefits associated with this gratuitous shareholding. This study assessed the financial benefits that have accrued to the Government of Ghana from its equity participation in the minerals sector. The coefficient of variation was also computed for revenues received from mineral royalty, corporate income tax, and free carried interest equity to determine revenue risk. Findings showed that dividend income from mining companies has been irregular and unreliable. Indeed, if the state obtained the noncontributory shareholding to earn extra income, then it could be replaced with more reliable alternatives such as a noncontributory preferential share or a minimal increase in the current royalty rate. Nonetheless, if ownership is the motivation, equity shares in local mines could also be swapped for shares in the corresponding offshore holding company so the state can benefit from the diversified portfolio of the holding company.

ABSTRACT The Canadian mining industry is on the threshold of a social transformation as it seeks to diversify its workforce and supply the critical minerals required for the global energy transition. Employees and leaders can be engaged, trained, and empowered to adopt a practice of inclusion—also known as allyship—in order to support the required transformation. In this study, researchers engaged 76 participants from the Canadian mining industry in a four-week allyship training program. Our findings show that learners’ allyship competencies and motivations to act as active workplace allies progressed during the course. As a result, participants are better equipped and more likely to engage in conversations about equity, diversity, and inclusion with their peers, subordinates, and leaders. Our findings suggest that leaders have an important role to play in fostering inclusive environments and sustaining allyship behaviors in others. Additionally, we offer insights into why organizations and their leaders should consider trauma-informed approaches to support the attraction and retention of a diverse workforce—an indicator of the successful social transformation.