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Toronto, Canada

Mostert M.,SRK Consulting
Journal of the Southern African Institute of Mining and Metallurgy | Year: 2014

Mining companies sponsor a range of non-core, corporate social responsibility projects to adhere to social and labour plans and environmental management prerequisites that form part of a mining licence application. Some companies go above and beyond such projects, sponsoring initiatives that generate renewable energy through solar power, wind energy, natural gas, etc. The challenge for these companies is to choose between a variety of projects to ensure maximum value, especially in times when the economic climate might be less favourable for such projects. The focus of this research was to analyse the concept of sustainability as it exists today, and to apply that to the triple bottom line accounting method in an attempt to quantify the sustainability of a project. Research was done on the methane burn-off project at Sibanye Gold's Beatrix Mine to establish how such projects are planned and financed, and what impact they have on the triple bottom line of a company. The financial bottom line is, by definition, one that executives understand. This paper also proposes a quantitative method for defining the social and environmental bottom lines as well. By considering the financial, social, and environmental values, the study attempts to determine a monetary value for a sustainable renewable energy project. This monetary value can be compared to similar values obtained for other sustainable renewable energy projects under consideration. The research suggests that monetary value alone is not enough to base a sustainable decision on, and qualitative measures are suggested for use in conjunction with quantitative methods. The selection method proposed should assist the board of a mining company to choose the most sustainable option and the project that will add the greatest value to the company across all three bottom lines. It will also provide increased justification for such renewable energy projects, even in periods of harsh or uncertain economic climates. © The Southern African Institute of Mining and Metallurgy, 2014.

There were considered the key approaches to resolving of problems, arising in the time of exploitation of Russian and CIS countries gold-mining enterprises, where alkaline cyanide solutions are used. There were compared the international and Russian requirements to neutralization of cyanide wastes of gold-mining industry. International cyanide classification was carried out. Processes of natural detoxification of cyanide compounds in tailings impoundment were considered. There were described the current Russian regulations, relating to purification of waste waters from cyanide ions and thiocyanates which are free and bounded to complex compound with metal ions. Efficiency of purification of cyanide waste waters and possibility of their discharge into water flows have the following determining indices: values of maximum allowable concentrations, dissolved in water; standard of admissible exposure and standard of admissible discharge. This article shows the Russian approach to assessment of hazard of solid wastes, which appear as a result of semi-dry storage of cyanide leaching cakes in complete sludge process, and gold heap leaching. It was noted that it is rather easy to destroy the most toxic free cyanides by a variety of methods, harmless for humans and fauna. However, even after complete destruction of cyanide compounds, dissolved in water, obtained waste waters should be dissolved by pure water or with additional purification measures. The indicators, which most frequently exceed the standard concentrations in de-cyanided water, include pH value, total salt content, products of decomposition of cyanide ions and cyanide destroying reagents, and some by-products of ore and concentrate leaching process which do not contain CN anions. 1. Ritcey G. M. Tailings management: problems and solutions in the mining industry. Amsterdam, New York: Elsevier, 1989. 970 p.

Fernandez-Alonso M.,Royal Museum for Central Africa | Cutten H.,Geological Survey of Western Australia | De Waele B.,SRK Consulting | Tack L.,Royal Museum for Central Africa | And 3 more authors.
Precambrian Research | Year: 2012

The Mesoproterozoic Kibara Belt (also Kibaran Belt or Kibarides in some references) of Central Africa was often portrayed as a continuous, c. 1500 km long orogenic belt, trending NE to NNE from Katanga, Democratic Republic of Congo (DRC) in the south, up into SW Uganda in the north. Recently however, the Karagwe-Ankole Belt (KAB; formerly the NE Kibara Belt) has been redefined as the part north of a NW oriented Palaeoproterozoic basement high of the Ubende-Rusizi Belts, while the Kibara Belt (KIB) is now limited to the part south of this rise.We present a lithostratigraphy for the KAB that takes into account two rheologically contrasting structural domains (Western and Eastern Domain); each of them being characterised by independent sedimentary sub basin(s) and depositional conditions: the ED with Archaean basement versus the WD with Palaeoproterozoic basement. We document new volcanic and detrital U-Pb SHRIMP zircon data which provide new constraints on the timing of deposition and on the detrital provenance of the sedimentary sequences in the KAB. We discuss the evolution of the KAB in a wider regional context, comparing it to other Mesoproterozoic units and with reference to the general geodynamic history of this part of the African continent in Proterozoic times.The lithostratigraphic successions of the KAB are only valid respectively in the ED (Kagera Supergroup) or in the WD (Akanyaru Supergroup), with no correlations between them. Deposition of the Kagera Supergroup in the ED is bracketed between 1.78. Ga and 1.37. Ga and the deposits have to be considered an Eburnean-age "molasse" . Detrital components comprise material only of Archaean and Palaeoproterozoic age, consistent with derivation from nearby source regions. In the WD, deposition of the two lowermost groups of the Akanyaru Supergroup is bracketed between 1.42. Ga and 1.37. Ga. The large contribution of detrital Palaeoproterozoic components in the WD strengthens the view that this domain is underlain by Palaeoproterozoic basement and supports the concept that part of the Akanyaru Supergroup sediments consists of reworked Eburnean-aged molasse. In the WD of the Kivu-Maniema area (DRC), later sedimentation periods are documented at respectively 1222. Ma and 710. Ma. The KAB documents a long-lived period of intracratonic intermittent depositional activity (with periods of interruption of deposition, erosion and magmatism) showing a recurrent subsidence trend controlled by structural activity moving with time from E to W.On a regional scale, we postulate that since 1.8. Ga, following the amalgamation of Archaean and Palaeoproterozoic landmasses into a single coherent 'proto-Congo Craton', various long-lived shallow-water intracratonic basins (aulacogenes) developed. These basins underwent a comparable Mesoproterozoic geodynamic evolution, as shown not only in the sequences of the KAB and of the relatively close Kibara (KIB), Bangweulu Block and Northern Irumide Belts, but even in more distant sequences located in SW Angola and E Brazil.The long-lived aulacogene history of the KAB within the proto-Congo Craton is interrupted only twice by short-lived compressional deformation reflecting far-field effects of global orogenic events, external to the proto-Congo Craton. The first event at 1.0. Ga is related to Rodinia amalgamation. The second event at 550. Ma results from Gondwana amalgamation and develops a N-S Pan African overprint in the KAB which has previously been underestimated or even overlooked. Three mineralisation provinces occurring in the KAB, respectively the Bushveld-type, the tin-coltan-wolfram and the gold province, can be ascribed successively to the 1375. Ma Kibaran magmatic event, the 1.0. Ga Rodinia and the 550. Ma Gondwana amalgamation events.Our results give additional weight to the recent redefinition of the KAB and the KIB, forming two distinct Belts respectively north and south of the Palaeoproterozoic basement high of the Ubende-Rusizi Belts, the more that within this basement rise local Mesoproterozoic strike-slip basins, with their own unique lithostratigraphic and geodynamic characteristics (e.g. Itiaso Group) are documented, which differ from those of the KAB or the KIB. © 2012 Elsevier B.V.

The article describes non-oxidation methods of detoxication of cyanide solutions and slurries, based on binding of cyanide ions into insoluble or relatively low-toxic strong compounds. Such technologies include precipitation of CN- anion in the form of low solubility compounds, such as ferric ferrocyanide/Turnbull's blue, Fe4[Fe(CN)6]3, FeNa[Fe(CN)6], or binding of this anion with thyocyanate anion, interacting with polysulfide compounds (DTOX technology). Both considered methods do not provide the results, corresponding to existing Russian environmental regulations. Using ion-exchange resin (anion resin), cyanide solution detoxication method helps to reduce the environmental impact, but can not solve all issues. Its industrial application requires significant dilution of waste solutions with fresh water, following their treatment by ion-exchange resin, which is not always possible. The article also describes the latest developments in oxidation of cyanide ions by atmospheric oxygen on activated carbon as catalyst. Nowadays, this method is not commercially used, but it can become a prospective development in future. © Designed by: "Ore and Metals" Publishing House.

Wu L.,University of Wisconsin - Madison | Beard B.L.,University of Wisconsin - Madison | Roden E.E.,University of Wisconsin - Madison | Kennedy C.B.,SRK Consulting | Johnson C.M.,University of Wisconsin - Madison
Geochimica et Cosmochimica Acta | Year: 2010

Stable Fe isotope fractionations were investigated during exposure of hematite to aqueous Fe(II) under conditions of variable Fe(II)/hematite ratios, the presence/absence of dissolved Si, and neutral versus alkaline pH. When Fe(II) undergoes electron transfer to hematite, Fe(II) is initially oxidized to Fe(III), and structural Fe(III) on the hematite surface is reduced to Fe(II). During this redox reaction, the newly formed reactive Fe(III) layer becomes enriched in heavy Fe isotopes and light Fe isotopes partition into aqueous and sorbed Fe(II). Our results indicate that in most cases the reactive Fe(III) that undergoes isotopic exchange accounts for less than one octahedral layer on the hematite surface. With higher Fe(II)/hematite molar ratios, and the presence of dissolved Si at alkaline pH, stable Fe isotope fractionations move away from those expected for equilibrium between aqueous Fe(II) and hematite, towards those expected for aqueous Fe(II) and goethite. These results point to formation of new phases on the hematite surface as a result of distortion of Fe-O bonds and Si polymerization at high pH. Our findings demonstrate how stable Fe isotope fractionations can be used to investigate changes in surface Fe phases during exposure of Fe(III) oxides to aqueous Fe(II) under different environmental conditions. These results confirm the coupled electron and atom exchange mechanism proposed to explain Fe isotope fractionation during dissimilatory iron reduction (DIR). Although abiologic Fe(II)aq - oxide interaction will produce low δ56Fe values for Fe(II)aq, similar to that produced by Fe(II) oxidation, only small quantities of low-δ56Fe Fe(II)aq are formed by these processes. In contrast, DIR, which continually exposes new surface Fe(III) atoms during reduction, as well as production of Fe(II), remains the most efficient mechanism for generating large quantities of low-δ56Fe aqueous Fe(II) in many natural systems. © 2010 Elsevier Ltd.

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