scholarly journals Elucidating Pathfinding Elements from the Kubi Gold Mine in Ghana

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 912
Author(s):  
Gabriel K. Nzulu ◽  
Babak Bakhit ◽  
Hans Högberg ◽  
Lars Hultman ◽  
Martin Magnuson
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Weathering ◽  
Gold Mining ◽  
Coarse Grained ◽  
Small Scale ◽  
X Ray ◽  
Mining Sites ◽  
Fine Grained ◽  
Exploration Area ◽  
Indicator Minerals

X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) are applied to investigate the properties of fine-grained concentrates on artisanal, small-scale gold mining samples from the Kubi Gold Project of the Asante Gold Corporation near Dunwka-on-Offin in the Central Region of Ghana. Both techniques show that the Au-containing residual sediments are dominated by the host elements Fe, Ag, Al, N, O, Si, Hg, and Ti that either form alloys with gold or with inherent elements in the sediments. For comparison, a bulk nugget sample mainly consisting of Au forms an electrum, i.e., a solid solution with Ag. Untreated (impure) sediments, fine-grained Au concentrate, coarse-grained Au concentrate, and processed ore (Au bulk/nugget) samples were found to contain clusters of O, C, N, and Ag, with Au concentrations significantly lower than that of the related elements. This finding can be attributed to primary geochemical dispersion, which evolved from the crystallization of magma and hydrothermal liquids as well as the migration of metasomatic elements and the rapid rate of chemical weathering of lateralization in secondary processes. The results indicate that Si and Ag are strongly concomitant with Au because of their eutectic characteristics, while N, C, and O follow alongside because of their affinity to Si. These non-noble elements thus act as pathfinders for Au ores in the exploration area. This paper further discusses relationships between gold and sediments of auriferous lodes as key to determining indicator minerals of gold in mining sites.

scholarly journals Assessment of the Challenges in Policy Implementation in the Small Scale Gold Mining Sector in Ghana – A Case Study

2017 ◽  
Vol 17 (1) ◽  
pp. 54-63 ◽  
Author(s):  
P. Arroja Eshun ◽  
E. Okyere
Keyword(s):  
Policy Implementation ◽  
Gold Mining ◽  
Small Scale ◽  
Mining District ◽  
Test Case ◽  
Mining Sector ◽  
Social Challenges ◽  
Mining Sites ◽  
Adequate Knowledge ◽  
Acquisition Processes

In recent times, stakeholders in the mining sector have expressed concerns about the environmental degradation and the social impacts of uncontrolled Small Scale Mining (SSM) activities in Ghana despite the existence of legislative instruments that define the procedures required for the acquisition of licences and operations of SSM activities in the country. This paper assesses the challenges in policy implementation in the small scale gold mining sector of Ghana by reviewing policies on regularisation and environmental management. It further identifies challenges faced by small scale mining operators in adhering to laid down policies for the smooth operation of the sector and furthermore assesses the views of some principal stakeholders on the benefits and challenges of small scale mining using the Dunkwa mining district as a test case. The methods employed include: field visits to some  small scale mining sites within the Dunkwa mining district; interviews and questionnaire administration; and statistical and content analysis of data. The study reveals the following factors, among others, to have contributed largely to the difficulty in regularisation, environmental and social challenges that have plagued the SSM sector: low level of education of majority of miners; bureaucracies and centralisation of licence acquisition processes; lack of sources of finance for SSM projects; lack of geological information on mineable areas; and lack of adequate knowledge of the laws and regulations on mining and environment. In addressing the challenges the following recommendations are made: decentralisation of the regularisation processes to simplify licence acquisition; adequate geological investigations should be undertaken on SSM blocked-out areas to reduce the try and error mining approach adopted by miners; and continuous education and training of miners on good mining and environmental practices. Keywords: Small Scale Mining, Mineral Policies, Environmental Impact, Regularisation, Challenges

scholarly journals Heavy Metals in the Soils of Placer Small-Scale Gold Mining Sites in Myanmar

2020 ◽  
Vol 10 (27) ◽  
pp. 200911
Author(s):  
Aung Zaw Tun ◽  
Pokkate Wongsasuluk ◽  
Wattasit Siriwong
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Gold Mining ◽  
Soil Samples ◽  
Small Scale ◽  
Mining Activities ◽  
Mining Operations ◽  
Metal Concentrations ◽  
Mining Sites ◽  
Heavy Metal Concentrations

Background. Artisanal and small-scale mining activities are widely practiced globally. Concentrations of heavy metals associated with gold, such as copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) can increase in the environment as a result of mining activities, leading to environmental pollution and pose toxicity risks to humans and animals. Objectives. The aim of the present study was to investigate soil concentrations of toxic heavy metals in placer small-scale gold mining operations in Myanmar. Methods. Soil samples were collected from three placer small-scale gold mining sites: Site A located in the Hmawbon public protected forest, Site B and Site C, situated in the Nant-Kyin reserved forest around Nar Nant Htun village. At each site, soil samples were collected from four gold mining stages (ore processing, sluicing, panning, and amalgamation). Atomic absorption spectroscopy was utilized to examine the concentrations of As, Cd, Pb, and Hg. Results. The highest heavy metal concentrations were generally found in the amalgamation stages across all the gold mining sites. Across the three mining sites, the maximum heavy metal concentrations in the amalgamation stage were 22.170 mg.kg−1 for As, 3.070 mg.kg−1 for Cd, 77.440 mg.kg−1 for Hg, and 210.000 mg.kg−1 for Pb. Conclusions. The present study examined the concentrations of As, Cd, Hg and Pb in the soil of several small-scale gold mining sites in Banmauk Township, Myanmar. The results demonstrated the presence of high concentrations of heavy metals in the soil of the gold mining sites. Miners in this area work without proper personal protective equipment, and frequent exposure to heavy metals in the soil may cause adverse health effects. The present study provides baseline data for future risk assessment studies of heavy metal contamination in gold mines. Competing Interests. The authors declare no competing financial interests

The Impact of Grain Size on Oxidation Behavior of TP304H Austenitic Stainless Steel at High Temperature in Air

2011 ◽  
Vol 117-119 ◽  
pp. 990-994
Author(s):  
Wei Wei ◽  
Zhi Wu Wang ◽  
Mao Lin Liu
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Oxide Scale ◽  
Grain Refinement ◽  
Coarse Grained ◽  
X Ray ◽  
Fine Grained ◽  
Different Grain Size ◽  
The Impact

Exposed to 650°C air, TP304H stainless steel with two different grain size was oxidized at this temperature. At the meantime, comparison of their oxidation was through the oxidation kinetics curves and analysis of the morphology and composition of oxide scale which conducted by SEM and X-ray. The results showed that the oxidation rate of TP304H stainless steel was slowed down by grain refinement and oxide scale of fine-grained TP304H steel was thinner than that of coarse-grained steel. The nucleation and the growth of nuclei of coarse-grained oxide scale were more rapid. In addition, the grain refinement of austenitic stainless steel accelerated the diffusivity of Cr and made for the formation of dense and continuous oxide scale, so that the oxidation of stainless steel can be effectively inhabited.

The effects of hydrodynamic sorting on the Ti isotope composition of sediments

2020 ◽  
Author(s):  
Martijn Klaver ◽  
Pieter Vroon ◽  
Marc-Alban Millet
Keyword(s):  
Chemical Weathering ◽  
Isotope Composition ◽  
Eastern Mediterranean ◽  
Hf Isotope ◽  
Passive Margin ◽  
Coarse Grained ◽  
Fine Grained ◽  
Crustal Composition ◽  
Mass Dependent ◽  
Physical And Chemical

<p>Detrital sediments provide a useful tool to investigate the composition of the continental crust through time. Mass-dependent (“stable”) isotope variations in Archaean to present-day sediments (shales, diamictites) have recently received much attention and Ti, in particular, holds significant promise as a novel tracer of crustal composition [1, 2, 3]. This approach is based on i) the contrasting Ti isotope composition of mafic versus felsic rocks as a result of the removal of isotopically light oxides during igneous differentiation; and ii) the chemical behaviour of Ti, a refractory and biologically inert element that should not fractionate during weathering and sedimentation. Hence, current interpretations of the Ti isotope detrital sediment record rely heavily on the assumption that it reflects the integrated composition of the source(s), and thus provides a record of the proportion of felsic to mafic rocks in that source.</p><p>A potential caveat, however, is the hydrodynamic sorting of dense minerals in coarse, more proximal sediments [4]. This effect is well-known for zircon; coarser sediments tend to have higher Zr/Al<sub>2</sub>O<sub>3</sub> and a less radiogenic Hf isotope composition due to the concentration of zircon grains [e.g., 5, 6]. Shales form the complementary zircon-depleted reservoir characterised by lower Zr/Al<sub>2</sub>O<sub>3</sub> and a more radiogenic Hf isotope composition relative to the source. Common Ti-rich phases such as ilmenite and rutile are also resistant against physical and chemical weathering and could be concentrated together with zircon in coarse sediments.</p><p>We examined a suite of Eastern Mediterranean passive margin sediments with well-constrained provenance [7] and found that Ti indeed behaves like Zr. Fine-grained samples have lower TiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> compared to coarser, proximal deposits of identical provenance. The removal of Ti-rich phases with a light Ti isotope composition into coarse-grained sediments could thus bias the Ti isotope composition of shales towards isotopically heavier values. We will report on the δ<sup>49/47</sup>Ti isotope composition of these sediment samples, but a TiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> mass balance suggests that a bias of more than 0.05 ‰ in the δ<sup>49/47</sup>Ti of shales is possible. Understanding the consequences of hydrodynamic sorting for Ti isotopes in sediments is crucial for their use as a quantitative proxy of crustal composition and for reconciling the shale and diamictite Ti isotope records.</p><p>[1] Greber <em>et al.</em> (2017) <em>Science</em> <strong>357</strong> 1271-1274; [2] Deng <em>et al.</em> (2019) <em>PNAS</em> <strong>116-4</strong> 1132-1135; [3] Saji <em>et al.</em> (2019) <em>Goldschmidt abstract</em> <strong>2929</strong>; [4] Greber & Dauphas (2019) <em>GCA</em> <strong>255</strong> 247-264; [5] Patchett <em>et al.</em> (1984) <em>EPSL</em> <strong>69</strong> 365-378; [6] Carpentier <em>et al.</em> (2009) <em>EPSL</em> <strong>287</strong> 86-99; [7] Klaver <em>et al.</em> (2015) <em>GCA</em> <strong>153</strong> 149-168.</p>

Deforestation and forest regeneration following small-scale gold mining in the Amazon: the case of Suriname

2001 ◽  
Vol 28 (2) ◽  
pp. 117-126 ◽  
Author(s):  
Garry D. Peterson ◽  
Marieke Heemskerk
Keyword(s):  
Gold Mining ◽  
Forest Cover ◽  
Qualitative Interviews ◽  
Gold Rush ◽  
Forest Recovery ◽  
Small Scale ◽  
Old Growth ◽  
Mining Sites ◽  
Mining Areas ◽  
Old Growth Forest

Despite scientific concern about Amazon deforestation and the impacts of the Amazon gold rush, few researchers have assessed the long-term impacts of small-scale gold mining on forest cover. This study estimates deforestation from gold mining and analyses the regeneration of abandoned mining areas in the Suriname Amazon. Fieldwork in December 1998 included observations and ecological measurements, as well as qualitative interviews with local miners about mining history and technology. Vegetation cover of abandoned mining sites of different ages was compared with that in old-growth forest. By present estimates, gold miners clear 48–96 km2 of old-growth forest in Suriname annually. Based on different assumptions about changes in technology and the amount of mining that takes place on previously mined sites, cumulative deforestation is expected to reach 750–2280 km2 by 2010. Furthermore, the analysis of abandoned mining sites suggests that forest recovery following mining is slow and qualitatively inferior compared to regeneration following other land uses. Unlike areas in nearby old-growth forest, large parts of mined areas remain bare ground, grass, and standing water. The area deforested by mining may seem relatively small, but given the slow forest recovery and the concentration of mining in selected areas, small-scale gold mining is expected to reduce local forest cover and ecosystem services in regions where mining takes place.

scholarly journals Artisanal and Small-Scale Gold Mining in Syanyonja, Busia Gold District, South Eastern Uganda: Impacts on the Mining Population and the Environment

2019 ◽  
Author(s):  
Timothy Omara ◽  
Shakilah Karungi ◽  
Stephen Ssebulime ◽  
Kibet Mohamed Kiplagat ◽  
Ocident Bongomin ◽  
...  
Keyword(s):  
Gold Mining ◽  
Shear Zones ◽  
Gold Deposits ◽  
Small Scale ◽  
School Dropouts ◽  
Mining Sites ◽  
Environmental Footprints ◽  
Metavolcanic Rocks ◽  
The Republic ◽  
Mining Population

Syanyonja village in the gold district of Busia, South East of the Republic of Uganda contain geologically epigenetic gold quartz vein deposits in carbonate-altered mafic metavolcanic rocks, deposited as quartz reefs in mineralized shear zones. In supracrustal rocks, alluvial gold is obtained from weathered auriferous quartz veins, which are of late orogenic granitic activity. The Syanyonja gold deposits have long been subjected to artisanal and small-scale gold mining (ASGM) by the locals for livelihood. This study determined the amount of mercury discharged with tailings into Namukombe stream, a major water body in Syanyonja village and investigated the impacts of ASGM on the mining population and the environment. Quantitation of mercury discharged with tailings was done by mass balance method. Field survey at the mining sites was done followed by administration of questionnaires to 50 stampeders in the village. The study indicates that about 8% of mercury mixed with auriferous materials are lost in tailings, accounting for an annual mercury release of about 1.757 kg into the environment. Socio-demographic results indicate that the majority of the mining population (64%) are male and ASGM have left health and environmental footprints, which directly or indirectly affects the population. The most common health problems among miners are malaria (36%) and abdominal pain (20%). The standard of living of the miners are evidently low, and most mines are characterized by school dropouts, prostitutes and thieves. Mining sites have deplorably poor hygiene, with evident burning of amalgams to recover gold. ASGM have been accompanied by wanton mowing down of vegetation, land degradation as well as mercuric pollution of water, air, land and aquatic ecosystems. It is suggested that the Ugandan government should re-enforce committees to follow up on ASGM activities, train artisans on sustainable gold mining using borax, magnets, sluice boxes as well as take up farming actively as an alternative.

scholarly journals Interfacial Reactions and Fracture Behavior of Ti Alloy-Ag28Cu Brazing Joints: Influence of Titanium Alloy Composition

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 830 ◽  
Author(s):  
Joachim Gussone ◽  
Galina Kasperovich ◽  
Jan Haubrich ◽  
Guillermo Requena
Keyword(s):  
Titanium Alloys ◽  
Fracture Behavior ◽  
Titanium Substrate ◽  
Tensile Tests ◽  
Coarse Grained ◽  
X Ray ◽  
Fine Grained ◽  
Β Phase ◽  
Brazed Joints ◽  
Crack Paths

Brazing of titanium provides a joining technique suitable for the fabrication of highly-loaded aerospace components, but it still poses numerous challenges, such as the formation of brittle intermetallic interphases. This study of the interphase formation in brazed joints consisting of different titanium alloys (Ti-CP2, Ti-CP4, Ti-6Al-4V, Ti-6Al-2Mo-4Zr-2Sn) and Ag28Cu shows that complex reactions lead to the formation of various intermetallic phases including a Ti2Cu-TiCu boundary zone. The compositions of the titanium alloys influenced the particular microstructures, which have been characterized with various methods including synchrotron X-ray microtomography. Tensile tests evidence high ultimate tensile strengths that are, importantly, not directly limited by the strength of the brazing alloy. The strength of the Ti2Cu-TiCu phase boundary is significantly increased by the alloying elements in Ti-6Al-4V and Ti-6Al-2Mo-4Zr-2Sn and the crack paths change from boundary failure to transcrystalline fracture through TiCu as well as Ag-rich regions. Cu diffusion into the titanium substrate, leading to a coarse grained β-phase that transforms eutectoidally into a lamellar α-Ti + Ti2Cu structure during cooling, occurred in all systems except Ti-6Al-2Mo-4Zr-2Sn where Mo stabilized a fine grained microstructure and enabled the formation of a columnar TiCu structure.

An X-ray method for studying orientation of micaceous minerals in shales, clays, and similar materials

1953 ◽  
Vol 30 (220) ◽  
pp. 71-78 ◽  
Author(s):  
G. W. Brindley
Keyword(s):  
Bedding Plane ◽  
Coarse Grained ◽  
Ray Method ◽  
X Ray ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Degree Of Orientation ◽  
Similar Materials ◽  
Ray Methods ◽  
Microscopic Techniques

Micaceous minerals, such as the micas, the chlorites, and most clay minerals, usually develop as thin lamellae parallel to the crystallographic basal plane (001). In sedimentary deposits these lamellae tend to lie parallel to the bedding plane and in slates parallel to the cleavage. Their degree of orientation is likely to vary with the conditions of formation of the material, and in the case of slates Bates (1947) has shown that it is closely related to their fissility. In relatively coarse-grained materials the degree of orientation may be studied directly by suitable microscopic techniques, but with fine-grained materials X-ray methods must be used, and even with coarser-grained materials the use of X-ray methods may have advantages, especially if a scanning technique, such as that described by Thewlis and Pollock (1950), is employed.

scholarly journals Quantitative grain-scale ferroic domain volume fractions and domain switching strains from three-dimensional X-ray diffraction data

2015 ◽  
Vol 48 (3) ◽  
pp. 882-889 ◽  
Author(s):  
Jette Oddershede ◽  
Marta Majkut ◽  
Qinghua Cao ◽  
Søren Schmidt ◽  
Jonathan P. Wright ◽  
...  
Keyword(s):  
Domain Switching ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Bulk Sample ◽  
Coarse Grained ◽  
X Ray Diffraction ◽  
X Ray ◽  
Volume Fractions ◽  
Fine Grained ◽  
Ferroic Materials

A method for the extension of the three-dimensional X-ray diffraction technique to allow the extraction of domain volume fractions in polycrystalline ferroic materials is presented. This method gives access to quantitative domain volume fractions of hundreds of independent embedded grains within a bulk sample. Such information is critical to furthering our understanding of the grain-scale interactions of ferroic domains and their influence on bulk properties. The method also provides a validation tool for mesoscopic ferroic domain modelling efforts. The mathematical formulations presented here are applied to tetragonal coarse-grained Ba0.88Ca0.12Zr0.06Ti0.94O3and rhombohedral fine-grained (0.82)Bi0.5Na0.5TiO3–(0.18)Bi0.5K0.5TiO3electroceramic materials. The fitted volume fraction information is used to calculate grain-scale non-180° ferroelectric domain switching strains. The absolute errors are found to be approximately 0.01 and 0.03% for the tetragonal and rhombohedral cases, which had maximum theoretical domain switching strains of 0.47 and 0.54%, respectively. Limitations and possible extensions of the technique are discussed.

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