Gold Mining Operations Research Articles

Effects of the government's ban in Ghana on women in artisanal and small-scale gold mining

Artisanal and small-scale gold mining operations have been conducted in Ghana for centuries. Over time, technological advances in the industry occurred and miners separated from large-scale mining and applied this knowledge to small-scale or individual mining practices. In March 2017, the government responded to a media campaign against environmental degradation and placed a ban against water pollution; this ban affected all informal gold mining operations because of the chronic use of mercury in gold extraction, which contributes to water contamination. The unintended consequences of this ban were that approximately 1 million people lost their jobs. A qualitative study was conducted to understand how small-scale gold mining affected female miners and in turn, the implications of the ban on these women and their families. There were 21 illegal female miners interviewed in Akwatia, Ghana. The results from this study confirmed that many female miners used their mining money to support their families. Because the ban blocked mining employment opportunities, the women were forced into unreliable and low-paying alternative jobs and were unable to pay for school fees and food. Unfortunately, while the ban may have improved the environment, it also contributed to adverse outcomes related to women and children's development, like inadequate nutritional needs and school dropout rates; thus, bans like this need to be reconsidered and readapted to address these immeasurable consequences.

A Global Look at Mercury Exposures: Supporting the Goals of the Minamata Convention.

A Global Look at Mercury Exposures: Supporting the Goals of the Minamata Convention.

Application of Multivariate Statistical Analysis to Identify Water Sources in A Coastal Gold Mine, Shandong, China

Submarine mine water inrush has become a problem that must be urgently solved in coastal gold mining operations in Shandong, China. Research on water in subway systems introduced classifications for the types of mine groundwater and then established the functions used to identify each type of water sample. We analyzed 31 water samples from −375 m underground using multivariate statistical analysis methods. Cluster analysis combined with principle component analysis and factor analysis divided water samples into two types, with one type being near the F3 fault. Principal component analysis identified four principle components accounting for 91.79% of the total variation. These four principle components represented almost all the information about the water samples, which were then used as clustering variables. A Bayes model created by discriminant analysis demonstrated that water samples could also be divided into two types, which was consistent with the cluster analysis result. The type of water samples could be determined by placing Na+ and CHO3− concentrations of water samples into Bayes functions. The results demonstrated that F3, which is a regional fault and runs across the whole Xishan gold mine, may be the potential channel for water inrush, providing valuable information for predicting the possibility of water inrush and thus reducing the costs of the mining operation.

The AKOBEN programme as a tool towards responsible gold mining in Ghana, business as usual or a commitment towards sustainable development

The AKOBEN Programme, an environmental performance rating and disclosure initiative that show the environmental performance of gold mining firms with reference to their daily activities post environmental impact assessment and issuance of an environmental permit was introduced in Ghana to serve as a monitoring and verification tool towards environmental compliance and responsible mining. As to whether the AKOBEN Programme is enhancing the environment and or safeguarding public health in Ghana needs to be investigated. A systematic multi-methods environmental audit approach comprising of comparative analysis, time series analysis, air and water quality indices were used within the framework of the Driver-Pressure-State-Impact-Response to answer the questions what is happening to the environment and what the consequences for the environment and humanity are. The quality and suitability of River Kwabrafo as a habitat for aquatic life, for agricultural, recreational and drinking purposes pre and post AKOBEN Programme introduction as well as the quality of agricultural soils and river sediments in gold mining communities was determined. The study revealed that the AKOBEN Programme rates gold mining firms based on variable-by-variable concentrations of toxic water pollutants such as As, Cd, Hg, CN and non-toxic water pollutants such as pH, suspended solids, dissolved solids and electrical conductivity without taking into account the cumulative effect of the pollutants and the various uses of water. Results on the quality of River Kwabrafo based on the Canadian Council of Ministers of the Environment Water Quality Index confirmed no differences in water quality concerning use for agriculture, recreation, drinking and as a habitat for aquatic life before and after the introduction of the AKOBEN Programme. The study also revealed the quality of air at Anyinam to be acceptable with reference to PM10 and unhealthy with reference to total suspended particulate (TSP). The AKOBEN Programme failed to delineate TSP into oxides of nitrogen, carbon dioxide, methyl mercury and oxides of sulphur for which reason the impacts of greenhouse gases and methyl mercury on the Obuasi Municipality could not be investigated under the AKOBEN Programme. Mean arsenic concentrations for all study sites exceeded the arsenic reference for Ghana with significant differences existing between mean soil Cd and Hg levels at AKOBEN sites, Non-AKOBEN sites and Control sites. This study will not only elucidate the environmental and health problems associated with gold mining operations at AKOBEN and Non-AKOBEN sites in Ghana, but will also present complex water quality data into simple communication format for easy understanding to policy makers and non-expert audience.

Bio-oxidation of refractory gold ores containing stibnite and gudmundite

Abstract Arsenic and antimony are environmental pollutants associated with several diseases, including skin cancer. One of the main sources of both elements is the oxidation of sulphide minerals, particularly arsenopyrite and therefore any of both elements is a concern in gold mining operations because arsenic- and antimony-bearing sulphides may contain significant gold contents. Bioleaching is considered more environmentally-friendly than chemical processes to recovery gold, particularly from low-grade ores and residues bearing such sulphides. Thus, the current work has investigated the bio-oxidation of both a gold-bearing sulphide concentrate and a flotation tailing by Acidithiobacillus ferrooxidans, at 32 °C, focusing on the behaviour of both arsenic and antimony. Fe2＋ supplementations were required in order to increase the oxidation efficiency and the optimum pH value was 1.75. The cyanidation tests confirmed the refractory nature of the samples under study (21%). The solid products of the bio-oxidation stage showed gold extractions four times as large (85%) as that of the initial sample. The dissolution of antimony was low with no evidence of the formation antimony precipitates. Unlike arsenic, the latter reported mostly to the solid product of the bioleaching step as inert sulphide particles.

The Political Ecology of Landscape Change, Malaria, and Cumulative Vulnerability in Central Ghana’s Gold Mining Country

Following the 2008 global financial crisis, small-scale gold mining operations proliferated worldwide. Along Ghana’s Offin River, the landscape has been radically transformed by mining, including disruptions to agriculture and surface hydrology, with adverse health outcomes. Yet, health research on small-scale mining tends to focus on miners’ mercury exposure. Further, studies on the relationships between disease and landscape change typically examine disease clustering and risk factor identification, rather than complex nature–society dynamics shaping infection and uneven vulnerability. Combining ethnographic, remote sensing, and quantitative methodological approaches, we detail how the socioecological outcomes of mining—from food insecurity and water-logged pits to profound anxiety and mercury contamination—combine to increase local malaria incidence. We argue that these changes interact with existing sociostructural conditions and Plasmodium falciparum’s unique biological capacities to render women and children most vulnerable to the disease. We suggest that mental health profoundly shapes malaria incidence and, countering individualized constructions of risk, family members’ health is deeply interconnected. This article contributes to current geographic debates in several ways. First, a cumulative vulnerability approach helps scholars conceptualize how biological, psychological, structural, and social conditions interrelate to shape humans’ conjunctural vulnerabilities along axes of difference, particularly in health contexts. We also highlight the importance of materiality in mediating vulnerability and malaria dynamics. Finally, we argue for more scholarly attention to familial relationships of care and mental health, heretofore unexplored topics in political ecologies of health.

A case study on the height of a water-flow fracture zone above undersea mining: Sanshandao Gold Mine, China

In undersea gold mines, the development of a water-flow fracture zone and its connection with the aquifer may cause massive water and sand inrush disasters. In this study, approaches including theoretical analysis, numerical simulation and field detection are employed to identify the development height of the water-flow fracture zone caused by undersea mining in the Xinli Zone of the Sanshandao Gold Mine to ensure mining safety. An improved Winkler elastic foundation beam model, considering the coupled influences of seawater pressure and backfill support, was established to calculate the height of the water-flow fracture zone. The result demonstrates that the height of the water-flow fracture zone depends on the elastic modulus of the overburden strata and the compression modulus of the filling material. Then, an experimental study utilizing a custom-made apparatus is conducted to obtain the Winkler foundation compression characteristics of the filling material used in the gold mining operation. The theoretical analyses are confirmed by numerical simulations and show that the height of the water-flow fracture zone decreases with the increase in mining level because the loads from overburden weight decreases with the mining depth. The theoretical analysis, numerical simulation and field detection present that the height of the mining-induced water-flow fracture zone is 39 m, 37 m, and 40.5–45 m, respectively, after mining at the − 135 m level. These values are reasonably consistent, suggesting that the proposed theoretical and numerical models and the utilized field detection method can provide valuable information for determining the overburden stability of an undersea mineral seam and improving mining safety.

Yellow Woman: Suspicion and Cooperation on Liberia's Gold Mines

ABSTRACTYellow Woman is a multimodal ethnographic research project combining text and film to explore the dynamics of cooperation and suspicion on a Liberian gold mine. The sixteen‐minute single‐take video places the viewer in a uniquely “filmic” position; in other words, it allows the viewer to experience the end of a gold mining operation as only a camera can render it. But it is a point of view that simultaneously captures the tensions and surveillance practices of mine bosses and the laborers themselves. These men, despite the collective nature of their work and their long associations with one another, nevertheless remain constantly vigilant against the possibilities of deception and theft. The text that accompanies the film provides the ethnographic context that the film itself cannot and explores the aesthetic and stylistic choices through which the film communicates. [ethnographic film, mining, Liberia]

Incessant Risk Alarms Associated with Farming and Consuming Crops Cultivated in Host Communities of Gold Mining Operations in Ghana: Truth, Exaggeration, Ignorance or Mischief

Heavy metals and metalloids, some of which are extremely beneficial for the survival of humans, flora and fauna can have devastating effects on same and the environment. Bioaccumulation and bio-magnification two methods via which metals and metalloids are assimilated into food chains as well as dermal and ingestion exposure to heavy metals and metalloids are believed by many residents in the Obuasi Municipality as leading public health threats to peasant farmers, their spouses and children. Risk assessment for three scenarios viz children, adult males and adult females were investigated using Average Daily Intake, Hazard Quotient and Hazard Index for ingestion and dermal exposure to metals and metalloids in soils at reclaimed sites backfilled with waste materials.

Gold in Ghana: The effects of changes in large-scale mining on artisanal and small-scale mining (ASM)

Two scales of gold mining operations, artisanal and small-scale mining (ASM) and large-scale mining, have operated side by side in Ghana for decades. In the past, the two co-existed on the same mineralised land without much contact or conflict, as large-scale mining occurred underground and ASM operated mainly on the surface. With the former’s transition from an underground labour-intensive mining operation to capital-intensive surface activity, however, opportunities for wage employment have reduced leading to labour retrenchment. Using an informalisation theoretical framework, and drawing on fieldwork conducted in the three gold mining towns of Obuasi, Prestea and Kenyasi, this paper explores how the interface between large-scale mining and ASM has evolved. It is shown how the loss of wage employment opportunities in large-scale mining has contributed to the proliferation of illegal ASM operations. As large-scale surface mining operations have reduced access to mineralised land by ASM, the latter have encroached on to the concessions of the former resulting in conflicts between these parties. It is ASM rather than large-scale mining, however, that is sustaining local economies in Ghana. As the economic well-being of mining towns is linked largely to the fortune of their mining economies, it is imperative that an innovative approach is adopted by the state in addressing the need for ASMs to access mineralised land.

Mercury Exposure: Impact on Birth Outcomes in Suriname

BackgroundSmall-scale gold-mining operations in Suriname use mercury (Hg) for gold extraction. Exposure during pregnancy can negatively influence birth outcomes and neurodevelopment. The Caribbean ...

Mercury content in the fur of jaguars (Panthera onca) from two areas under different levels of gold mining impact in the Brazilian Pantanal.

The Pantanal is the largest inland wetland in the world and is under increasing anthropogenic threats, including long-term regionally intensive gold mining practices. Gold mining activities are known to cause the release of harmful pollutants such as mercury (Hg) to the surrounding environment. Jaguars (Panthera onca (Linnaeus, 1758)) are apex predators, and therefore show great potential to accumulate Hg by biomagnification. We hypothesize that total Hg content in the fur of jaguars from two sites within the Brazilian Pantanal would be significantly different as a function of distance from active gold mining operations. The Hg content was determined by fluorescence spectrometry. The mean ± SD Hg content in jaguars from the study site influenced by gold mining (SB) was compared to jaguars sampled in the area free of gold mining activities (CA) using a one-way ANOVA. The mean Hg content in jaguars from SB (673.0 ± 916.8 µg g-1) is significantly different from jaguars sampled in CA (29.7 ± 23.3 µg g-1), p = 0.03. The maximum recorded content of Hg was 2,010.4 ± 150.5 µg g-1, highest level ever recorded in a wild animal. The data indicate that Hg is an important threat to jaguars within at-risk regions of the Pantanal.

A comparison of factors affecting the small-scale distribution of mercury from artisanal small-scale gold mining in a Zimbabwean stream system

Artisanal small-scale gold mining (ASGM) operations use mercury liberally in the gold extraction process and account for approximately one quarter of the anthropogenic mercury consumption worldwide. ASGM activities are concentrated in many impoverished and poorly regulated countries such as Zimbabwe, resulting in a number of negative impacts to health and the environment. To examine levels of mercury contamination in one such geographic locality, sediment and tailing samples were collected in a heavily mined watershed in southern Zimbabwe from May–June 2015. Samples were collected from multiple points within the stream system, as well as from around six stamp mills and a single industrial mine in the watershed. GPS point location data were taken for mining operations and sampling sites to examine the spatial patterns of mercury concentration. Data were first analyzed using linear regression and development of a MARS model, followed by application of an ANCOVA model to assess the relationship among mercury concentrations and percent organic material, distance downstream, and distance from potential contamination source. Mercury concentrations within the study area ranged from 6 to 1541 μg/kg dw (mean 142 μg/kg dw). Analyses of mercury concentrations indicated a positive relationship with percent organic material but a negative relationship with distance downstream and distance from potential contamination source. Results from this study help elucidate the relationship between gold production and the spatial scale of mercury contamination in aquatic ecosystems in Africa. These data may lead to a better understanding of the relationship between mercury use and community health, which may aid both the local and global communities in regulating mercury contamination of the environment.

What killed Frame Lake? A precautionary tale for urban planners.

Frame Lake, located within the city of Yellowknife, Northwest Territories, Canada, has been identified as requiring significant remediation due to its steadily declining water quality and inability to support fish by the 1970s. Former gold mining operations and urbanization around the lake have been suspected as probable causes for the decline in water quality. While these land-use activities are well documented, little information is available regarding their impact on the lake itself. For this reason, Arcellinida, a group of shelled protozoans known to be reliable bioindicators of land-use change, were used to develop a hydroecological history of the lake. The purpose of this study was to use Arcellinida to: (1) document the contamination history of the lake, particularly related to arsenic (As) associated with aerial deposition from mine roaster stacks; (2) track the progress of water quality deterioration in Frame Lake related to mining, urbanization and other activities; and (3) identify any evidence of natural remediation within the lake. Arcellinida assemblages were assessed at 1-cm intervals through the upper 30 cm of a freeze core obtained from Frame Lake. The assemblages were statistically compared to geochemical and loss-on-ignition results from the core to document the contamination and degradation of conditions in the lake. The chronology of limnological changes recorded in the lake sediments were derived from 210Pb, 14C dating and known stratigraphic events. The progress of urbanization near the lake was tracked using aerial photography. Using Spearman correlations, the five most significant environmental variables impacting Arcellinida distribution were identified as minerogenics, organics, As, iron and mercury (p < 0.05; n = 30). Based on CONISS and ANOSIM analysis, three Arcellinida assemblages are identified. These include the Baseline Limnological Conditions Assemblage (BLCA), ranging from 17–30 cm and deposited in the early Holocene >7,000 years before present; the As Contamination Assemblage (ACA), ranging from 7–16 cm, deposited after ∼1962 when sedimentation began in the lake again following a long hiatus that spanned to the early Holocene; and the Eutrophication Assemblage (EA), ranging from 1–6 cm, comprised of sediments deposited after 1990 following the cessation of As and other metal contaminations. The EA developed in response to nutrient-rich waters entering the lake derived from the urbanization of the lake catchment and a reduction in lake circulation associated with the development at the lake outlet of a major road, later replaced by a causeway with rarely open sluiceways. The eutrophic condition currently charactering the lake—as evidenced by a population explosion of eutrophication indicator taxa Cucurbitella tricuspis—likely led to a massive increase in macrophyte growth and winter fish-kills. This ecological shift ultimately led to a system dominated by Hirudinea (leeches) and cessation of the lake as a recreational area.

A new model for open-pit production and waste-dump scheduling

ABSTRACTAn open-pit mine schedule defines the optimal sequence of mining valuable (ore) and waste material with the objective of maximizing the value of the project. Given this production schedule, a waste-dump schedule is then developed to determine the optimal waste-rock allocation in waste dumps. Thus, production and waste-dump schedules are managed separately, which leads to an inappropriate consideration of the material haulage cost, suboptimal schedules generating less value, and the incorrect classification of ore and waste. This article proposes a mixed-integer programming-based model that determines the optimal production and waste-rock dumping schedule concurrently with the objective of maximizing the discounted cash flow [net present value (NPV)] of the project. An implementation of the proposed model on a gold-mining operation outperforms the two existing methods [traditional and two-step mixed-integer programming (TSMIP) model] in the context of project NPV as well as its practicality.

Arsenic Geochemistry of Alluvial Sediments and Pore Waters Affected by Mine Tailings along the Belle Fourche and Cheyenne River Floodplains

Gold mining operations in the northern Black Hills of South Dakota resulted in the discharge of arsenopyrite-bearing mine tailings into Whitewood Creek from 1876 to 1977. Those tailings were transported further downstream along the Belle Fourche River, the Cheyenne River, and the Missouri River. An estimated 110 million metric tons of tailings remain stored in alluvial deposits of the Belle Fourche and Cheyenne Rivers. Pore-water dialysis samplers were deployed in the channel and backwaters of the Belle Fourche and Cheyenne Rivers to determine temporal and seasonal changes in the geochemistry of groundwater in alluvial sediments. Alluvial sediment adjacent to the dialysis samplers were cored for geochemical analysis. In comparison to US Environmental Protection Agency drinking water standards and reference concentrations of alluvial sediment not containing mine tailings, the Belle Fourche River sites had elevated concentrations of arsenic in pore water (2570 μg/L compared to 10 μg/L) and sediment (1010 ppm compared to < 34 ppm), respectively. Pore water arsenic concentration was affected by dissolution of iron oxyhydroxides under reducing conditions. Sequential extraction of iron and arsenic from sediment cores indicates that substantial quantities of soluble metals were present. Dissolution of arsenic sorbed to alluvial sediment particles appears to be affected by changing groundwater levels that cause shifts in redox conditions. Bioreductive processes did not appear to be a substantial transport pathway but could affect speciation of arsenic, especially at the Cheyenne River sampling sites where microbial activity was determined to be greater than at Belle Fourche sampling sites.

Spatial distribution patterns of illegal artisanal small scale gold mining (Galamsey) operations in Ghana: A focus on the Western Region

Recently, there have been efforts by stakeholders to monitor illegal mining (galamsey) activities, foster their formalization and reclaim the many abandoned wastelands in Ghana. However, limited information exists on the locations, abundance, scope and scale of galamsey types, which hinders the development of effective policy response.This study attempts to map and analyze the distribution patterns, abundance, activity statuses and the extents of nine (9) galamsey types within eleven (11) Municipal and District Assemblies (MDAs) of Ghana's Western Region. It explores the utility of field-based survey, using the Open Data Kit (ODK) system, ArcGIS and Google Earth Imagery to map and visualize different galamsey types under a hostile working environment. A total of 911 galamsey sightings, of which 547 were found in clusters (corresponding to approximately 7106 individual operational units) and 364 in stand-alone mode. Overall, a total of 7470 individual galamsey operations were encountered in 312 different communities (towns and villages).Operationally, the Alluvial Washing Board, Mill-House and Chamfi were found to be the three most popular and practiced galamsey types. The three main galamsey hotspot districts (out of the 11) are the Tarkwa Nsuaem (294 sightings and 3648 individual galamsey sites), Amenfi East (223 sightings and 1397 individual galamsey sites) and Prestea Huni-Valley Districts (156 sightings and 1130 individual galamsey sites). In terms of their activity statuses, 199 abandoned operations (entailing 1855 individual operations), 664 active (entailing 5055 individuals operations) and 48 semi-active (comprising 560 individuals within clusters) galamsey operations were sighted at the time of the study.While galamsey is generally acknowledged to be widespread in Ghana, the results suggest a scale that probably surpasses any previous estimate or expectation. The findings will adequately inform the prioritization of reclamation efforts.

Applicability of the chromium reducible sulfur test for acid metalliferous drainage prediction in hard rock mining

The potential for Acid and Metalliferous Drainage (AMD) from waste rock in mining operations is a key issue which must be addressed at all stages, from the initial mining proposal to rehabilitation and site closure. The Chromium Reducible Sulfur (CRS) method was originally introduced into Australia as a rapid and cost-effective method to estimate the acid production potential of acid sulfate soils. However, concerns are being raised over its potentially inappropriate use without supporting scientific evidence to assess the AMD potential of mine wastes in hard rock mining, especially those containing base metal (lead, zinc, copper and nickel) sulfides.This paper outlines the results of a comparative laboratory study of 55 Western Australian mine waste samples and mineral specimens for AMD potential using CRS results from routine commercial laboratories normally handling soil samples as well as conventional approaches. CRS was found to be generally suitable for many applications, particularly for common iron sulfides at low to moderate concentrations (relevant to many iron ore, mineral sands and gold mining operations). However, CRS was not a reliable predictor of potential acid production from samples containing elevated concentrations of iron sulfides, base metal sulfides, arsenopyrite or molybdenite. Issues with CRS precision and bias were also indicated. A good understanding of sulfide mineralogy is required for accurate AMD predictions of these types of mine wastes, and cannot be obtained from any single test.

Proof of concept for a passive sampler for monitoring of gaseous elemental mercury in artisanal gold mining

Mercury emissions from artisanal gold mining operations occurring in roughly 80 developing countries are a major workplace health hazard for millions of people as well as the largest contributor to global mercury pollution. There are no portable, cheap, and rapid methods able to inform workers or health practitioners of mercury exposure on site in remote locations. In this work, a proof of concept for a miniaturized mercury sampler, prepared by the direct reduction of gold into the porous nanostructures of Vycor glass (PVG), is introduced. Mercury retention on the PVG/Au sampler induces significant color changes, due to the formation of Au-Hg amalgam that affects the surface plasmon resonance characteristics of the material. The color change can potentially be quantified by the analysis of pictures obtained with a cell phone camera rapidly and onsite. Laboratory experiments showed the viability of using PVG/Au as passive sampler for monitoring of Hg°. PVG/Au samplers were then deployed in an artisanal and small-scale gold mining (ASGM) operations in Burkina Faso and it was able to indicate personal mercury exposures. The amount of mercury quantified in the samplers for all miners was higher than the current personal exposure limit set by the US Occupational Safety & Health Administration (OSHA).

Arsenic mobility in weathered gold mine tailings under a low-organic soil cover

Historical gold mining operations in Nova Scotia, Canada, resulted in numerous deposits of publicly accessible, arsenic (As)-rich mine waste that has weathered in situ for 75–150 years, resulting in a wide range of As-bearing secondary minerals. The geochemical heterogeneity of this mine waste creates a challenge for identifying a single remediation approach that will limit As mobility. A 30-cm-thick, low-organic content soil cover was evaluated in a laboratory leaching experiment where, to simulate natural conditions, the equivalent of 2 years of synthetic rainwater was leached through each column and two dry seasons were incorporated into the leaching protocol. Each column was a stratigraphic representation of the four major tailings types found at the historical Montague and Goldenville gold mine districts: hardpan tailings, oxic tailings, wetland tailings, and high Ca tailings. Hardpan tailings released acidic, As-rich waters (max 12 mg/L) under the soil cover but this acidity was buffered by surrounding oxic tailings. Leachate from the oxic tailings was circumneutral, with average As concentrations between 4.4 and 9.7 mg/L throughout the experiment. The presence of carbonates in the high Ca tailings resulted in near-neutral to weakly alkaline leachate pH values and average As concentrations between 2.1 and 6.1 mg/L. Oxidation of sulfides in the wetland tailings led to acidic leachate over time and a decrease in As concentrations to values that were generally less than 1 mg/L. This study shows that the use of a low-organic content soil cover does not create reducing conditions that would destabilize oxidized, As-bearing secondary phases in these tailings. However, oxygen penetration through the cover during dry seasons would continue to release As to tailings pore waters via sulfide oxidation reactions.