Largest Gold Mine Research Articles

Water Quality of Roof-Harvested Drinking Water Tanks in a Rural Area near a Gold and Copper Mine: Potential Health Risk from a Layer of Metal-Enriched Water and Sediment

This study investigated the drinking water quality of house water tanks that harvested roof runoff in a rural area surrounding a large copper and gold mine in Central Western New South Wales (NSW). Water was sampled from (1) the tops of water tanks, (2) the bottoms of water tanks, and (3) kitchen taps. Water samples collected from the bottoms of tanks were turbid with suspended sediment. Concentrations of metals (lead, nickel, arsenic and manganese) from bottom-of-tank water samples often exceeded Australian drinking water guidelines. Overall, 37.2% of samples from bottoms of tanks exceeded arsenic guidelines (<10 µg L−1). The mean concentration of lead in water from bottoms of tanks was 695 µg L−1, with 18.6% of these samples exceeding lead guidelines (<10 µg L−1) by >100 times. Our results highlight the risk of contaminated water and sediment at the bottoms of tanks. Further investigation of private household drinking water tanks is recommended for properties in other rural areas, including areas with and without nearby mining activity. We describe a layer of contaminated water and sediment at the bottoms of water tanks, near the water outlet, which is a potential contamination pathway and substantial health risk for house water supplies.

Rockburst hazard assessment and prevention and control strategies in the Ruihai gold mine

Ruihai gold mine is a super large underwater gold mine with an initial mining depth of more than 1,400 m. Deep mining may face rockburst disaster. In order to scientifically control the potential rockburst risk, ensure the safety of underground personnel and equipment, and realize the safe and efficient mining of the mine, it is necessary to evaluate the rockburst risk of the mine and formulate appropriate rockburst risk warning and mitigation strategies. XRD mineral composition analysis and conventional rock mechanical tests were carried out on the parent rock granite samples. The results show that there are differences in the lithologic composition and rock mechanics parameters of the three colors of granite, which are preliminarily determined as three kinds of granite; The rockburst tendency of three kinds of granites is evaluated by using three classical rockburst criteria, and the discrimination results of the three rockburst criteria are not completely consistent or even contradictory. The application limitations rockburst risk assessment based on index criteria are discussed and analyzed in detail. It is proposed to apply microseismic monitoring technology to warn and manage the rockburst risk of Ruihai gold mine in development and mining stages, and put forward microseismic monitoring layout schemes and targeted rockburst prevention and control measures in different stages. The research results can provide reference for similar projects.

Mercury deposition to lake sediments near historic gold mines in northern Canada

Mercury (Hg) contamination in aquatic systems can lead to adverse human and environmental health outcomes. Yellowknife, a city in Canada’s Northwest Territories, is a historic mining community, with two large gold mines (Giant Mine and Con Mine) that used Hg amalgamation methods to extract gold between ∼1938 and 1960. We analyzed dated sediment cores from 20 small lakes to investigate the spatial and temporal Hg deposition patterns within 50 km of Giant Mine. Breakpoint analysis of the within-lake z-score normalized anthropogenic Hg flux indicates two significant time periods of changing emission rates. The first is a significant increase in Hg deposition rate (∼1925) during the time of gold exploration in the region and onset of Hg amalgamation (1938) and the second is a significant decrease in deposition rate that begins around the time of the cessation of Hg amalgamation at Giant Mine (∼1959). Sediment Hg concentrations exceeded the Canadian Council for Ministers of the Environment Interim Sediment Quality Guideline (ISQG) for Hg (0.17 mg/kg dw) in 55% of the lakes (n = 11) during mining (1948–1999). All lakes within 5 km of the Giant Mine roaster stack exceeded CCME ISQG during mining (n = 8), with a 4-fold increase in total Hg concentration observed during mining at these near-field (<5 km from stack) sites. We observed evidence of enriched Hg in near-field, mid-field, and far-field sites. The elevated sedimentary Hg concentrations during mining in near-field sites would have posed a hazard to human and wildlife health during the height of emissions, however the significant decrease in Hg concentrations since the closure of mines in the region demonstrate the potential for recovery in these aquatic ecosystems.

Characteristics of Gold Minerals in Gold Concentrate with a High Copper Content and Effective Gold Recovery via Flotation and Ammonia Pretreatment–Cyanidation Leaching

The characteristics of ultrafine gold minerals in gold concentrate with a high copper content produced by a large gold mining company in Shandong Province were determined via chemical composition analysis, phase analysis, and mineral liberation analysis. The results showed that the concentrate contained 48.13 g/t gold, which was mainly in the form of native gold and electrum. Regarding the gold mineral particles, 57.65% were completely liberated and 35.75% were associated with chalcopyrite and pyrite. The remainder mainly comprised wrapped intergrowths. The cumulative distributions of native gold and electrum fractions with diameters of less than 75 µm were 82.55% and 90.15%, respectively. Enhanced Cu–S bulk flotation, and then, Cu–S separation from the raw material were proposed to effectively enrich the gold minerals and decrease the treatment throughput during the leaching operation. The optimized conditions yielded a concentrate with a high copper content (3.89% Cu and 545.62 g/t Au contents, and 83.15% Cu and 77.54% Au recoveries) and a concentrate with a high sulfur content (0.059% Cu and 15.03 g/t Au contents, and 83.15% Cu and 21.28% Au recoveries). The capacity of the subsequent leaching process was reduced by 25%. Ammonia pretreatment was introduced to decrease the adverse effect of copper on cyanidation leaching for the copper concentrate. Under the optimized leaching conditions, gold dissolution reached 99.76%, which was approximately 4% higher than that obtained via direct leaching. The NaCN consumption decreased over 10 kg/t. These results could serve as a valuable reference for the economic and green utilization of gold resources from concentrate with a high copper content.

The Undeclared, Declassified: West New Guinea and the 1969 Act of Free Choice

This article deals with the ‘Act of Free Choice’ (AFC/Pepera) whereby Indonesia officially took control of West New Guinea under the auspices of the United Nations (UN). The event itself took place in 1969 as preordained in the terms of the New York Agreement of August 1962 drawn up by US diplomat, Ellsworth Bunker. In both the 1962 Agreement and the 1969 AFC, Adam Malik was the principal Indonesian participant; and in both, according to his 1969 Report, the role of the UN was really no more than a bystander. Yet it was the authority of the UN which ultimately provided approval of Indonesian sovereignty as the outcome of the AFC. How this came about is evident from a close inspection of US declassified telegrams from 1966-1999. Two principal questions arise: the first pertains to the motivation of the various US diplomats involved, such as Bunker, Marshall Green (US Ambassador to Indonesia 1965-69) and Henry Kissinger, who were linked to Rockefeller mining interests focused on gaining access to the world’s largest gold mine in West New Guinea; and the second pertains to the rights of the Papuan people as the inhabitants of the territory in question. In the written words and opinions of the persons who were actually involved in the preparation and execution of the AFC/Pepera, there is often no compunction in disregarding UN principles, and yet there is a willingness, when it suits, to utilize UN authority as the arbiter of international justice.

‘Zama Zama’ and leftovers: The recycling of ore in abandoned gold mines in South Africa

Despite increased restrictions and security measures imposed on abandoned gold mines by the South African government amidst recent deaths and the ongoing debate about the place of ‘illegal mining’, unlicensed miners, known as ‘zama zamas’ continue to insert themselves into the economy by engaging in practices of scavenging, recycling and reworking of leftover gold ore. Increasingly, abandoned gold mines exemplify the physical ruins that articulate the collapse of the regional mining industry despite the resurgence of the extractive industries in other African countries. While a growing body of literature deals with such miners, their working practices have not been approached from the perspective of recycling/reworking: a practice that is growing and which reveals aspects of the contemporary form that capitalism is taking. In South Africa recycling or reworking of gold bearing ore in abandoned commercial mines is a growing practice. The extraction of residual gold ore from the ruins of capital-intensive enterprises is carried out informally and, according to the state, illegally. This paper explores how, in response to the retrenchment of mine workers from South African mines and the ensuing high unemployment in the country and sub region, ordinary people have inserted themselves into the economy to rework the gold ore that has been left by large scale gold mining companies. It documents how ‘illegal’ miners extract and rework gold bearing ore in the ruins of commercial mines and how recycling becomes an integral part of their livelihood and trade. Finally, the paper draws on extant literature and the author's ethnographic observations of artisanal and small-scale miners, known as zama zamas, and uses innovation as a lens.

A new hazard assessment workflow to assess soil contamination from large and artisanal scale gold mining

Gold mining activities are undertaken both at large and artisanal scale, often resulting in serious ‘collateral’ environmental issues, including environmental pollution and hazard to human and ecosystem health. Furthermore, some of these activities are poorly regulated, which can produce long-lasting damage to the environment and local livelihoods. The aim of this study was to identify a new workflow model to discriminate anthropogenic versus geogenic enrichment in soils of gold mining regions. The Kedougou region (Senegal, West Africa) was used as a case study. Ninety-four soil samples (76 topsoils and 18 bottom soils) were collected over an area of 6,742 km2 and analysed for 53 chemical elements. Robust spatial mapping, compositional and geostatistical models were employed to evaluate sources and elemental footprint associated with geology and mining activities. Multivariate approaches highlighted anomalies in arsenic (As) and mercury (Hg) distribution in several areas. However, further interpretation with enrichment factor (EFs) and index of geoaccumulation (IGeo) emphasised high contamination levels in areas approximately coinciding with the ones where artisanal and small scale mining (ASGM) activities occur, and robust compositional contamination index (RCCI) isolated potentially harmful elements (PHE) contamination levels in very specific areas of the Kedougou mining region. The study underlined the importance of complementary approaches to identify anomalies and, more significantly, contamination by hazardous material. In particular, the analyses helped to identify discrete areas that would require to be surveyed in more detail to allow a comprehensive and thorough risk assessment, to investigate potential impacts to both human and ecosystem health.

“What does it mean to make a picture of the now?”

“What does it mean to make a picture of the now?”

Indonesian Artisanal and Small-Scale Gold Mining-A Narrative Literature Review.

Indonesia is host to a long history of gold mining and is responsible for a significant contribution to world gold production. This is true not only with regard to large gold mining companies but also to small-scale mining groups comprised of people and enterprises that participate in the gold industry of Indonesia. More than two thousand gold mining locations exist in present day Indonesia. Artisanal and small-scale gold mining (ASGM) sites are spread out across thirty provinces in Indonesia, and have provided work opportunities and income for more than two million people. However, the majority of ASGM activities use rudimentary technologies that have serious impacts upon the environment, public health, and miners’ safety, which in turn generate socio-economic impacts for people residing around the mine sites. Moreover, many ASGMs are not licensed and operate illegally, meaning that they are immune to governmental regulation, and do not provide income to the regions and states via taxes. The possibility for more prudent management of ASGM operations could become a reality with the involvement and cooperation of all relevant parties, especially communities, local government, police, and NGOs.

Предварительные итоги изучения флоры Нерчуганского заказника (Забайкальский Край)

The purpose of this work is to study the species composition and analysis of the flora of the «Nerchugansky» reserve. The Nerchugansky State Nature Reserve of regional significance was created in the Tungokochensky District of Zabaikalsky Krai, part of the Far Eastern Federal District, with the support of WWF Russia to preserve its natural heritage. This large protected area is situated in the basin of the Amur River – in the valley of the Nercha River and its most important tributary, the Nerchugan. The importance of this PA in terms of environmental safety is explained by the fact that several large placer gold mines operate in the region, which has a signifi cant negative impact on natural systems. The article presents the data of field studies of the terrestrial ecosystem of the reserve. As a result of the collected material, a systematic register of plant flora has been compiled with the allocation of leading families. The results of the chorological analysis are presented and the features of the formation of vegetation cover in this territory are revealed. The zonal and ecological classifications of the vegetation cover are distributed. The phytosozological analysis of the flora of the reserve was carried out. A number of rare and needy plant species have been identifi ed. The analysis of the flora of the first stage of the study showed the presence of 167 species from 112 genera belonging to 40 families, with the selection of the leading ones. Of these, 10 species belonging to 9 genera from 6 families are included in the Red Book of the Zabaikalsky (Trans-Baikal) Krai. This area is characterized by a diversity of forest communities as well as isolated relict areas of mountain steppes with high species diversity. Preservation of intact natural communities and development of mechanisms of sustainable nature management will preserve biodiversity and ecosystem services of the territory.

Mining habitat, house and home during an East African gold boom: economic and emotional dimensions

ABSTRACT This article interrogates migrants’ economic and emotionally entwined decision-making regarding migration and settlement in unfolding stages of a gold mining boom. Three Tanzanian gold mining settlements representing temporal, spatial and scalar differences along the gold mining trajectory are contrasted: an artisanal rush site, a mature artisanal mining settlement and Geita town, site of a large industrial gold mine. Our data derives from in-depth interviews with miners, traders, service providers and farmers supplemented by a household survey. Interviewees’ verbatim narratives describing their work and family life are laced with feelings of both anticipation and apprehension. Strategic calculations and contingency thinking combine with emotional anxiety as they pursue efforts to ‘get ahead’ during the mining boom. Amidst the uncertainty of stressful work lives, and obstacles to secure housing and residence in infrastructurally deficient, unsafe and polluted mining environments, a ‘deferred sense of home’ surfaces in many mining settlement residents’ narratives. Seeking a ‘comfortable and secure home eventually’ is a coping mechanism for bridging the gap between initial high expectations and their current material reality.

Environmental radioactivity in gold mining in Burkina Faso and potential recycling of mining waste rocks

ABSTRACT Naturally occurring radionuclides have been reported to occur in high concentrations in gold deposits and with other metal ores in Africa. These radionuclides can be released during mining operations and ore processing, causing harmful radiation exposure of mine workers and nearby populations, and may render the mining waste rocks unusable. One large gold mine site in Burkina Faso, near Mana Village, was assessed for naturally occurring radionuclide levels. The area was surveyed for ambient radiation dose rate. Samples from waste rock and sludge from ore milling were analysed by alpha spectrometry, confirming the presence of naturally occurring radionuclides but in relatively low concentrations. It was concluded that mine workers are not exposed to radiation doses significantly above the unmodified natural radiation background. Furthermore, waste rock piles from mining operations can be recycled and used in road construction.

Monitoring and risk-control of large-scale toppling failures - a case study from Ok Tedi

This paper presents the monitoring and management of a large-scale toppling failure that was first observed in 2005 at the Ok Tedi mine. Ok Tedi is a large open-cut copper gold mine in the Western Province of Papua New Guinea and is one of the wettest mines in the world (>10 m annual rainfall). The management of large-scale failures in open-pit mines expresses geotechnical challenges in terms of balancing economical designs and safe operations. The failure located at the southern end of the West Wall was reactivated in June 2019 due to continuous mining and prolonged rainfall events. Erosion, cracking, and rock toppling associated with lateral displacements, evolved rapidly. Hence, ground control and groundwater management plans, including a Trigger Action Response Plan (TARP) and measurements to monitor movement across the wall, were implemented. This monitoring system, associated with daily visual inspections, enhanced the understanding of the necessary controls to maintain a safe mining operation. Furthermore, the water management plan was crucial in managing this failure. The successful risk-control of this large-scale toppling failure at Ok Tedi ensured continuous mining with a functional balance between economic and safety during operations.

Pollution Assessment of Potentially Toxic Elements (PTEs) in Soils around the Yanzhuang Gold Mine Tailings Pond, Pinggu County, Beijing, China.

The accumulation of tailings from gold mining and smelting may result in PTE pollution. We investigated PTE contamination from a large amalgamated gold mine tailings pond in Pinggu County, Beijing. In November 2017, 30 soil samples were collected around the tailings pond. The concentrations and pollution degree of PTEs in the samples and the sources of Sb, As, Cd, Cu, Pb, Zn and Hg were analyzed. The average concentration of these elements in soil samples near the tailings pond (16.24, 28.29, 0.99, 171.04, 263.25, 99.73, 0.72 mg/kg, respectively) were higher than their corresponding standard values and background values of the study area. The geoaccumulation index showed that the pollution degree of As, Pb and Hg was moderate, while Sb and Cu present non-pollution to moderate pollution. The average EF values of the elements were Sb (38.31), As (4.23), Cd (0.71), Cu (3.68), Pb (21.24), Zn (0.82) and Hg (5.29), respectively. The environmental risk assessment developed throughout the PERI method indicated that Sb, As, Hg and Pb were the main pollutants in the study area. The three quantitative risk indicators (RI, Igeo and EF) were positively correlated, and all of them indicated that PTEs had significant pollution to the local area. Thus, Sb, As, Pb, Cu, and Hg pollution should be highly concerning. Multivariate statistical analysis shows that the pollution of PTEs was mainly caused by the accumulation of tailings ponds after gold mining and smelting. The research result is of great significance for the prevention and control of soil pollution of PTEs near the tailings pond.

Distribution and Assessment of Trace Elements Contamination in Sediments of Conceição River Basin, Brazil

The Conceição river basin, in Quadrilátero Ferrífero (Iron Quadrangle), Brazil, has a long mining history which dates back to the late 17th century, with large gold and iron mines. These activities may be associated with river sediment contamination by trace elements, which were evaluated in this paper by the enrichment factor (EF) and contamination factor (CF). Potential ecological risks, assessed by combining sediment quality control guidelines (SQCG) and potential ecological risk indexes (Er and RI), are presented. Anomalous values for As (92.5 mg·kg−1), Cd (22.49 mg·kg−1), Cr (2582 mg·kg−1), Cu (65.9 mg·kg−1), Pb (58.6 mg·kg−1) and Zn (133.4 mg·kg−1) are observed. The EF and CF indexes indicate contamination by Cd, Cr, Fe, Mn, Ni and Zn in at least one site, with the highest values for Fe and Mn downstream of the iron mines, and Cr and Ni close to the gold mines. According to the SQGC and Er, As, Cd, Cr, and Ni are the most probable to result in adverse effects on sediment-dwelling organisms in this study. The results of principal component analysis (PCA) indicate distinct lithological units as sources of the analyzed elements, which, associated with the indexes, made it possible for the first time to delimit and classify the high concentrations of some analyzed elements as contamination in the Conceição river basin.

Improving the Stability of Subsurface Structures in Deep Metal Mines by Stress and Energy Adjustment: A Case Study

In deep hard-rock mines, the failure of subsurface structures (e.g., tunnels, stopes, and shafts) has been a significant problem affecting mining safety due to the high-stress environment. In this paper, the mechanism of structural failure and instability is discussed, and optimized excavation methods are proposed for stress control in deep gold mines. Based on the field observation and investigation of the joints distribution and rock failure modes at 800–1200 m depth of several large gold mines and a typical ultradeep borehole (2017 m depth) in northwest Jiaodong Peninsula, three engineering methods for reducing stress, including the stress transferring by mining optimizations, pressure relief by boreholes, and energy release in advance by optimizations of excavation and support, are analyzed by numerical simulation and field monitoring. Results show that stress reduction by excavation alone is limited and the backfill mining method is more conducive to stress transfer than the opening stope method. Roof contacted backfill can produce an unloading zone around the stope and reduce the stress of the surrounding stope. Relief boreholes can reduce the stress concentration of stopes, but the effect of cutting seams generated by presplitting blasting on pressure relief is not significant. The technology “short excavation and short support” releases less energy. By increasing the bench height and the reasonable timing of support by calculating, the elastic strain energy of rock in the shaft is prereleased, which benefits the long-term stability of the shaft.

Does mercury emission from small-scale gold mining cause widespread soil pollution in Ghana?

The use of mercury in small-scale gold mining is globally the largest anthropogenic source of mercury in the environment. In countries like Ghana, where small-scale gold mining is a highly important economic sector, the activity is also expected to cause local pollution. This study is based on a hypothesis that the mining activity in Ghana is causing more widespread soil pollution also outside active mining sites, and that the main part of regional differences in soil concentrations of mercury might come from pollution. Little systematic and dependable data has been collected to assess the extent of mercury contamination of soils in areas outside active mining areas. The regional aspect of mercury pollution from mining has not been studied in Ghana or other countries with a large small-scale gold mining sector. Systematic collection of soil samples on a 25×25km2 net covering the entire country was carried out to ensure the representativeness of data and to allow calculation of spatial trends. The soil concentrations found in one-third of the country, where most intensive mining takes place, are three times higher than concentrations in the rest of the country. This difference cannot be explained by sources of natural variation in mercury concentrations but can be explained by decades of atmospheric deposition. It is therefore likely that the mining activity has caused a more widespread increase in soil concentrations, also outside active mining sites. The mercury concentrations found are on average 0.024mgkg-1, which is low compared to published studies from other countries and regions and estimated world averages. All measured concentrations are well below soil quality criteria for human health. The build-up of soil concentrations in the mining area is still problematic because mercury is a hazardous substance in the environment.

An Application of Simultaneous Stochastic Optimization at a Large Open-Pit Gold Mining Complex under Supply Uncertainty

The simultaneous stochastic optimization of mining complexes optimizes various components of the related mineral value chain jointly while considering material supply (geological) uncertainty. As a result, the optimization process capitalizes on the synergies between the components of the system while not only quantifying and considering geological uncertainty, but also producing strategic mine plans, maximizing the net present value. This paper presents an application of simultaneous stochastic optimization at a large gold mining complex. The complex contains three open-pit mines, three stockpiles, a waste dump, and a processing facility. Material hardness management is integrated at the processing facility. The case study generated production schedules for each mineral deposit considered, as well as an overall assessment of the project and related forecasts. It resulted in an 18 year life-of-asset and identified the semi-autogenous grinder (SAG) mill as the bottleneck of the operation.

Paradox of Informal Luxury Housing Boom in a Post-Mining Town in Ghana

This paper examines spontaneous construction of new housing in Obuasi, the largest gold mining town in Ghana after its closure in 2014. Obuasi has become spatially different as more new luxury houses have been developed by the former miners over a relatively short period without coordination. The paper explores the role of lump sum severance packages received from industrial collapse on housing. Using in-depth interviews with former miners who have built their houses after the mine closure, the reasons for the use of the severance packages to build and thoughts behind the choices of housing typologies have been discussed. This paper established that the former workers built their new houses with their take-home money to overcome the bottlenecks in the formal housing finance market and to fulfil continuity of “good-living” privileges previously enjoyed for working and living in the gold mines. The paper concludes that industrial workers should be provided livelihood options training before they are laid off from their respective employments. Keywords: Post-mining towns, Obuasi, informal housing, housing finance, Ghana DOI: 10.7176/JRDM/73-04 Publication date: February 28 th 2021

Access of migrant gold miners to compensation for occupational lung disease: Quantifying a legacy of injustice

BackgroundA legacy of the South African gold mining industry, now in decline, is a large burden of silicosis and tuberculosis among former migrant miners from rural South Africa and surrounding countries, particularly Lesotho and Mozambique. This neglected population faces significant barriers in filing claims for compensation for occupational lung disease. The objective of the study was to gain insight into the extent of such barriers, particularly for former miners and cross-border migrants. MethodsThe database of a large gold mining company and the statutory compensation authority were analyzed for the period 1973–2018 by country of origin, age, and employment status at the time of claim filing. Proportions and odds ratios (ORs) for each of the compensable diseases were calculated by the above variables. Processing delays of claims were also calculated. ResultsAnnual company employment declined from 240,718 in 1989 to 43,024 in 2018 and the proportion of cross-border migrants within the workforce from 51.0 to 28.1%. The compensation database contained 68,612 claims. The majority of compensable claims in all diagnostic categories were from active miners. The odds of cross-border miners relative to South African miners filing a claim depended on employment status. For example, the OR for Lesotho miners filing while in active employment was 1.86 (95% CI 1.81, 1.91), falling to 0.94 (95% CI 0.91, 0.98) among former miners. The equivalent findings for Mozambiquan miners were 0.95 (95% CI 0.91, 1.00), falling to 0.44 (95% CI 0.41, 0.47). Median processing delays over the whole period were from 1.1 years from filing to adjudication, and 3.8 years from filing to payment. ConclusionsThe findings provide a quantitative view of differential access to occupational lung disease compensation, including long processing delays, among groups of migrant miners from the South African gold mines. There is a deficit of compensable claims for silicosis and silico-tuberculosis among former miners irrespective of country of origin. While cross-border miner groups appear to file more claims while active, this is reversed once they leave employment. Current large-scale efforts to provide medical examinations and compensation justice to this migrant miner population need political and public support and scrutiny of progress.