Gold Mines In South Africa Research Articles

Testing the P/S Amplitude Seismic Source Discriminant at Local Distances Using Seismic Events Within and Surrounding the Kloof Gold Mine, South Africa, and the Kiruna Iron Ore Mine, Northern Sweden

ABSTRACT We investigate the utility of the P/S amplitude discriminant for small seismic events recorded at local distances on surface seismic networks using (1) mining-related events from within the Kloof gold mine in South Africa; and (2) mining-related events and earthquakes within and adjacent to the Kiruna iron ore mine in northern Sweden. For the Kloof mine, seventy-five source mechanisms characterized by moment tensor solutions obtained using high-frequency in-mine seismic data are used to evaluate three mine-related source types, isotropic (crush), compensated linear vector dipole (crush-slip), and double-couple (DC; pure slip). For the Kiruna mine region, 270 events are used to evaluate earthquake sources, chemical explosions, and mine-related seismic events (primarily isotropic). For the Kloof mine events, we find that average P/S amplitude ratios measured in the 2–6 Hz frequency band discriminate between isotropic and DC events, and if only pure-slip events with a DC component of >60% are considered, the effective frequency band can be extended from 2 to 8 Hz. For the Kiruna region events, P/S amplitude ratios effectively discriminate earthquakes from chemical explosions in the 4–6 Hz and 10–28 Hz frequency bands. Our findings further show that average P/S amplitude ratios for mine-related events and earthquakes separate at frequencies of 10 Hz and higher. A comparison of amplitude ratios for crush and pure-slip events located within a depth range of 1 km in the Kloof mine, and a comparison of amplitude ratios of shallow (<10 km depth) and deep-focus (>20 km depth) earthquakes in the Kiruna region, indicate that the P/S amplitude discriminant is not influenced significantly by source depth. These findings thus suggest that the P/S amplitude discriminant, originally developed for larger events recorded at regional and teleseismic distances, can be extended to smaller events recorded at local distances.

Considerations for occupational heat exposure: A scoping review

The ability to regulate core body temperature is a critical factor in avoiding occupational heart stress in demanding environments. Heat-related illness in an occupational setting is complex and multifactorial and includes environment (intrinsic and extrinsic), the occupational clothing requirements and physiological factors. Much of this research began in the gold mines in South Africa after several miners died due to heat related illness. Similar research was conducted during World War Two and was crucial for the creation of acclimatization techniques and strategies for acquiring thermal tolerance. Techniques such as fatigue recovery and body cooling are still used today to prevent heat related illness in individuals with occupations that have frequent exposure to heat and high physical loads. These individuals are at greater risk of heat related illness as extended exposure to a hot or humid environment in combination with strenuous physical activity can overwhelm the body’s homeostatic cooling mechanisms. In addition, individuals from special populations with chronic or acute health impacts such as diabetes mellitus, also have a greater risk for the aforementioned. Currently, there are several heat prevention strategies, including training and education, regulation and monitoring, in place to protect workers from heat related illness and casualty. These strategies, along with future considerations and the impact of climate change will be highlighted in this review.

IFN-γ independent markers of Mycobacterium tuberculosis exposure among male South African gold miners.

The prevalence of tuberculosis among men who work in the gold mines of South Africa is among the highest in the world, but a fraction of miners demonstrate consistently negative results upon tuberculin skin test (TST) and IFN-γ release assay (IGRA). We hypothesized that these "resisters" (RSTRs) may display unconventional immune signatures of exposure to M.tuberculosis (M.tb). In a cohort of RSTRs and matched controls with latent TB infection (LTBI), we profiled the functional breadth of M.tb antigen-specific T cell and antibody responses using multi-parameter flow cytometry and systems serology, respectively. RSTRs and LTBI controls both exhibited IFN-γ independent T-cell and IgG antibody responses to M.tb-specific antigens ESAT-6 and CFP-10. Antigen-specific antibody Fc galactosylation and sialylation were higher among RSTRs. In a combined T-cell and antibody analysis, M.tb lysate-stimulated TNF secretion by T cells correlated positively with levels of purified protein derivative-specific IgG. A multivariate model of the combined data was able to differentiate RSTR and LTBI subjects. IFN-γ independent immune signatures of exposure to M.tb, which are not detected by approved clinical diagnostics, are readily detectable in an occupational cohort uniquely characterized by intense and long-term infection pressure. Further, TNF may mediate a coordinated response between M.tb-specific T-cells and B-cells. This work was supported by the US National Institutes of Health (R01-AI124348 to Boom, Stein, and Hawn; R01-AI125189 and R01-AI146072 to Seshadri; and 75N93019C00071 to Fortune, Alter, Seshadri, and Boom), the Doris Duke Charitable Foundation (Davies), the Bill & Melinda Gates Foundation (OPP1151836 and OPP1109001 to Hawn; and OPP1151840 to Alter), Mass Life Science Foundation (Fortune), and Good Ventures Fund (Fortune).

Artisanal mining and its drivers in the South African context

In South Africa, Zama Zama mining is a colloquial term referring to artisanal mining. This type of mining is illegal, seeing that these mining activities are conducted without a mining license. Zama Zama mining is often associated with several social ills, for example, issues related to the miners’ health and safety, environmental deprivation, child labour and the occurrence of violence and conflict within the sector. South African mining companies and law enforcement officials tend to view the solution to these problems to lie in policing this sector but are achieving little success. This article suggests an alternative, more proactive approach by exploring the drivers of artisanal gold mining in South Africa and ascertaining the responsibilities of mining companies in mitigating the drivers. A re-examination of Zama Zama mining's marginalisation could replace the current reactive ways pursued through policing and criminalising the sector with more sustainable and proactive approaches to address the sector's problems.

‘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.

An underexploited invisible gold resource in the Archean sulphides of the Witwatersrand tailings dumps

The tailings dumps originating from gold mining in South Africa’s Witwatersrand still contain notable gold endowments. Most tailings reprocessing operations target a native gold fraction using re-milling and carbon-in-leach extraction; however, up to 50–70% of the remaining gold is still not recoverable and instead discarded to the re-dump stream along with abundant sulphides. The mineralogical deportment of this unrecoverable gold underwent a detailed investigation. Using in situ laser ablation ICP-MS mineral chemistry measurements, we show that this gold that is inaccessible to conventional recovery is hosted preferentially in pyrite and arsenian pyrite. Importantly, complementary optical and electron microscopy observations reveal that the rounded detrital forms of these minerals contain the highest gold concentrations (0.01–2730 ppm), showing some similarity to values reported for sulphides from primary orogenic gold deposits found in surrounding Archean-aged granite-greenstone belt remnants. We suggest that detrital auriferous sulphides have been overlooked by historical primary and secondary beneficiation, and thus represent a large (up to 420 tons Au) and under-exploited Au resource currently residing in easily-mined (surficial) Witwatersrand tailings dumps. We further suggest that targeted re-mining of sulphide mineral fraction has the potential to improve gold recovery, recuperate ‘sweetener’ by-product metals (e.g. Cu, Co, Ni) and directly eliminate heavy metal pollution and acid mine drainage issues associated with surficial tailings dumps.

The Night Trains: Moving Mozambican Miners to and from South Africa, 1902–1955

The Night Trains: Moving Mozambican Miners to and from South Africa, 1902–1955

Anthropocene Narratives of Living with Resource Extraction in Africa

AbstractAfrican experiences have so far not been central to Anthropocene debates. While the Anthropocene usefully theorizes the planetary dimensions of environmental change, how do its propositions hold when applied to specific and widely divergent settings? Drawing from three examples—copper mining in Zambia, gold mining in South Africa, and oil drilling in Nigeria—this article examines varied experiences of environmental change in the Anthropocene. Resource extraction, which moves tons of earth and heavily pollutes the air and soils, epitomizes the Anthropocene. In order to grasp ways of living with extraction and its toxic legacies in African localities, it is necessary to consider situated histories of capitalism and colonialism and how these have generated intersectional positionalities, in terms of gender, socioeconomic status, and race. These histories inform actors’ abilities to envisage alternatives to the Anthropocene in the present and future. Inspired by decolonial frameworks, this article begins to chart more plural ways to write the Anthropocene.

A corporate social responsibility conceptual framework to address artisanal gold mining in South Africa

The formal sector's role in supporting the informal sector is becoming more recognisable worldwide. In this regard, the International Labour Organisation (ILO, 2002: 73) remarked that it is becoming more difficult for corporations to maintain and improve circumstances in the formal economy without addressing the informal economy. To explore the role corporations can play in developing and addressing artisanal mining in South Africa, this paper engages with the theoretical domain of corporate social responsibility (CSR). Based on empirical data, a CSR framework was developed through the research, which is the first comprehensive framework that mining companies can use to address the current unsustainable artisanal mining sector in the South African context. The CSR framework provides practical initiatives to develop and create opportunities for historically disadvantaged South Africans to benefit from the country's mineral resources.

Stress State in the Source Region of Mw2.2 Earthquake in a Deep Gold Mine in South Africa Determined from Borehole Cores

In December 2007, an Mw2.2 earthquake occurred in a gabbroic dike at 3.3 km depth in a deep gold mine in South Africa. The fore- and aftershock activity was analyzed in an effort to understand the preparation and generation processes of earthquakes; these findings have already been published. The present paper focuses on the stress state in the source region of the mainshock. A 90-m-long borehole across the mainshock fault was drilled ~ 1.5 years after the mainshock and logged by an optical televiewer. The fault can be identified by severe damage to the borehole wall at the point where the borehole intersected the aftershock cluster. Except for a 10-m section in the hanging wall of the fault, borehole cores were fully recovered. Borehole breakout (BO) and core disking (CD) were found to occur. Two stress measurement techniques [Deformation Rate Analysis (DRA) and Diametrical Core Deformation Analysis (DCDA)] were applied to the borehole cores. By combining their results with occurrence criteria for BO and CD, the principal stress state in the source region of the mainshock was determined. The principal directions in the hanging wall of the fault were nearly identical to the virgin stress state, while it was significantly disturbed in the footwall. The vertical stresses were 106 MPa and 40 MPa in the hanging wall and footwall, respectively. The significant difference in the vertical stress between the two sides of the fault can be explained by the stress redistribution associated with a nonuniform slip on a nonplanar fault.

A case study of geotechnical conditions affecting mining-induced seismicity in a deep tabular mine

Seismic risk in the deep gold mines of South Africa has been studied for many decades. A clear understanding of the effect of geotechnical conditions on the seismic hazard nevertheless remains elusive. Certain reef types seem to be associated with a higher risk of rockbursts. The stability and deformation behaviour of excavations on the different reef horizons are affected by the rock types and the varying strength properties. The seismic response to mining is therefore also expected to differ according to the geotechnical conditions. As a case study of this behaviour, the seismicity at Mponeng mine was investigated. On the VCR (Ventersdorp Contact Reef) horizon, two areas can be delineated. On the eastern side of the mine, the footwall is shale, and on the western side it is a strong brittle quartzite. More large-magnitude events occur in the area with the shale footwall than the area with the quartzite footwall. Moment tensor analyses indicated that the majority of the large-magnitude events are not related to geological structures, but are face-related, implying that shear failure of intact rock is occurring ahead of the mining front. Preliminary modelling indicated that the closure volume for the shale footwall may be higher than that for the quartzite footwall, providing a possible explanation for the observed difference in seismic response.

COVID Roundtable

COVID Roundtable

SIMULATING THE SENSITIVITY OF UNDERGROUND VENTILATION NETWORKS TO FLUCTUATING AMBIENT CONDITIONS

The weather directly impacts ventilation systems, especially large industrial systems found in underground mines. Underground mine ventilation systems have high cost implications that add to the financial strains and uncertainties of future mining operations. In addition, the dynamic nature of underground ventilation systems makes the accurate prediction of underground conditions extremely difficult using traditional steady-state methods. Therefore, improved prediction methods of dynamic underground environmental conditions are needed to ensure cost-effective ventilation systems. This paper investigates simulating the sensitivity that underground ventilation systems have to fluctuating ambient conditions. Simulation software was applied to a case study on a gold mine in South Africa. The results showed that transient software can now be applied to entire mine ventilation systems, and can improve predicting the underground environment because of fluctuating ambient conditions.

Natural Radioactive Environments as Sources of Local Disequilibrium for the Emergence of Life.

Certain subterranean environments of Earth have naturally accumulated long-lived radionuclides, such as 238U, 232Th, and 40K, near the presence of liquid water. In these natural radioactive environments, water radiolysis can produce chemical species of biological importance, such as H2. Although the proposal of radioactive decay as an alternative source of energy for living systems has existed for >30 years, this hypothesis gained strength after the recent discovery of a peculiar ecosystem in a gold mine in South Africa, whose existence is dependent on chemical species produced by water radiolysis. In this study, we calculate the chemical disequilibrium generated locally by water radiolysis due to gamma radiation. We then analyze the possible contribution of this disequilibrium for the emergence of life, considering conditions of early Earth and having as reference the alkaline hydrothermal vent theory. Results from our kinetic model point out the similarities between the conditions caused by water radiolysis and those found on alkaline hydrothermal systems. Our model produces a steady increase of pH with time, which favors the formation of a natural electrochemical gradient and the precipitation of minerals with catalytic activity for protometabolism in this aqueous environment. We conclude by describing a possible free-energy conversion mechanism based on protometabolism, which could be a requisite for the emergence of life in Hadean Earth.

Systematic Framework toward a Highly Reliable Approach in Metal Accounting

ABSTRACT Metal accounting is becoming an area of growing focus because of the requirement for the resulting data to feed directly into financial reports. It is vital in the fulfillment of best corporate governance practices and to provide assurance on metallurgical processes. The current metal accounting practices deliver a number of important measures, but an essential change in the approach toward data integrated and auditable metal accounting system is an indispensable need. This work aims to present a systematic framework toward a highly reliable method in metal accounting. The proposed approach introduces a novel mining to product metal accounting scheme and conceptualization of an intelligent metallurgical and metal accounting information management system (MMAIMS). An open cast gold mine in South Africa is presented as a case study. Based on the results and discussions that we have presented in this study, it has been shown that the proposed intelligent MMAIMS will result in improved plant process control, transparent financial reporting, and a suitable understanding of interrelationships between different process activities. The intelligent MMAIMS approach will eradicate data security risks related to multiple-user environment spreadsheets, create reliability in data used for decision-making and operation data synchronization. End to end metal accounting process visibility across the whole process will advance the audibility and transparency of metal accounting from mine to product, and enable good corporate governance and financial reporting of the salable metal product concerning smart mining and mineral processing concept.

Modeling and analysis of Lily gold mine disasters using geoinformatics

On February 05 2016, a significant and unfortunate series of mine disasters occurred at the Lily gold mine in South Africa, where 79 mineworkers were trapped under a huge rock and soil mass. In this paper, two separate geographical information system based models are proposed; one for surface and one for subsurface mine disasters. The multi-temporal (2004–2017) high-resolution pre and post-disaster satellite images were analyzed to assess the magnitude and spatial extent of the surface disaster. The explicit modeling technique was applied for mine subsidence using the Mohr–Coulomb failure criterion under gravitational acceleration. For surface disaster, the weighted overlay model was applied by assigning weights to hydrological (rainfall, flow direction, accumulation, and density); geological (geology and lineaments) and geomorphological (slope, aspect, and curvature) causative factors. The mine subsidence modeling results showed a subsidence zone of 55 × 24 × 71 m due to a failure of a crown pillar, whereas, in reality, it was 60 × 30 × 80 m. The deformation results showed that the lamp room wherein the miners were trapped could have been displaced somewhere at or below level 5 but above level 6 towards the southwest direction. The output of surface disaster modeling was also satisfactory and reliable as the actual two slope failures, i.e. the western and southern landslides of the Lily gold mine, located in extreme risk zones as predicted by the model. The results of this study can be useful for future mine planning and the environmental improvements at the Lily gold mine.

Domestication of previously uncultivated Candidatus Desulforudis audaxviator from a deep aquifer in Siberia sheds light on its physiology and evolution.

An enigmatic uncultured member of Firmicutes, Candidatus Desulforudis audaxviator (CDA), is known by its genome retrieved from the deep gold mine in South Africa, where it formed a single-species ecosystem fuelled by hydrogen from water radiolysis. It was believed that in situ conditions CDA relied on scarce energy supply and did not divide for hundreds to thousand years. We have isolated CDA strain BYF from a 2-km-deep aquifer in Western Siberia and obtained a laboratory culture growing with a doubling time of 28.5 h. BYF uses not only H2 but also various organic electron donors for sulfate respiration. Growth required elemental iron, and ferrous iron did not substitute for it. A complex intracellular organization included gas vesicles, internal membranes, and electron-dense structures enriched in phosphorus, iron, and calcium. Genome comparison of BYF with the South African CDA revealed minimal differences mostly related to mobile elements and prophage insertions. Two genomes harbored <800 single-nucleotide polymorphisms and had nearly identical CRISPR loci. We suggest that spores with the gas vesicles may facilitate global distribution of CDA followed by colonization of suitable subsurface environments. Alternatively, a slow evolution rate in the deep subsurface could result in high genetic similarity of CDA populations at two sites spatially separated for hundreds of millions of years.

Study on mechanical properties of surrounding rock and shaft safety pillar in exploitation of extremely thin reef

In view of the engineering geological conditions of the extremely thin reef of platinum gold mine in South Africa, we researched the distribution of in-situ stress, seismic and fault, the relationship between UCS and loading and so on. On this basis, we delineated the shaft safety pillar by using 3D mining software, and analyzed the influence of safety pillar on shaft stability by using FLAC3D numerical simulation method. The results show that it is necessary to set up accurate safety pillars to ensure the stability of shaft even though the height of goaf is very small in the mining of extremely thin reef. Research shows that the safety pillar calculated by numerical simulation method is more accurate, which avoids the resources loss or poor security caused by the traditional method. It is easier to achieve the expression of two-dimensional plane, and is more convenient to calculate the volume amount of safety pillar. The research provides theoretical guidance for the mining design, and has important practical significance.

Manager-Employee Relationships during Turbulent Times at a Gold Mine in South Africa

This article aims to provide new conceptual insights into the responsibilities of an engineer who acts as a plant manager and who has to deal with employee relations during a turbulent time at a gold mining plant in South Africa. A qualitative research approach was used to gather the data in this study. Trustworthiness of the research was ensured by applying various reasoning strategies, such as content analysis, inductive reasoning, blending, bracketing and understanding in order to interpret the data. The first group interview comprised managers as well as engineers who were appointed as managers, the second, administrative employees from the service departments, and the third, artisans and foremen employed at the mine. Qualitative content analysis was used to analyse the transcripts. The recurring themes from the group interviews were ‘employee empowerment’, ‘trust building’, ‘employee voice’ and ‘development of skills’. A conceptual framework for manager-employee relations during troubled times was developed from the findings. The essential responsibilities of a gold mining plant manager during periods of turbulence were described.

Smart automated noise policy monitoring and feedback control system for mining application

Abstract This work develops an integrated smart noise monitoring model that can be used to monitor mine workers on site. The system provides mine administrators with the current state of hearing of the individual employee. The information obtained from the model can be used by the administration, for various purposes including monitoring and provision of early intervention. The main purpose of the model is to protect mining employees from experiencing significant hearing threshold shifts which can result in permanent hearing loss. The novelty of this model is the formulation of noise policy management model using feedback control with policies acting as actuators. Mining noise policies, Code of Practice and milestones are used in the selection of the appropriate controllers to be used in the system. Feedback is used in the system to compare the threshold output to the baseline. The output of the system is further processed using Internet of Things to ensure effective communication between the mine employees and the administrators. The model was validated using open source data from a real deep gold mine in South Africa. The results were generated using Matlab as a platform and were found to be comparable to the existing static model and more accurate. Future improvements to this work is to include artificial intelligence and machine learning concepts to the system to make it more robust.