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Cardiff, United Kingdom

Prichard H.M.,University of Cardiff | Fisher P.C.,University of Cardiff | McDonald I.,University of Cardiff | Knight R.D.,University of Cardiff | And 2 more authors.
Economic Geology | Year: 2013

The Spotted Quoll PGE-bearing Ni deposit in the Forrestania greenstone belt in the Archean Yilgarn block in Western Australia is a komatiite-associated massive sulfide orebody tectonically displaced from its original host. The brecciated ore contains clasts of quartz and garnet schist and is located along a shear zone overlain by banded iron formation (BIF) and underlain by BIF and quartz-biotite metasediments. The deformation of the ore has destroyed its magmatic textures and it has been sheared and recrystallized at amphibolite facies. Then the deformed ore has been subjected to a hydrothermal event that concentrated the PGE with Au and As, often at the edge of the Ni ore. The PGE are distributed between PGM and in solid solution in Ni sulfarsenides, and Pd also occurs in pentlandite. The PGM include sudburyite (PdSb), sperrylite (PtAs2), and irarsite (IrAsS). All six PGE and minor Au are hosted in gersdorffite (NiAsS). Two generations of gersdorffite have been recognized. A higher temperature magmatic euhedral Co-rich gersdorffite encloses Ir-, Pt- and Rh-bearing PGM surrounded by halos of Rh-, Ir-, and Os-rich gersdorffite. A lower temperature Ni-rich gersdorffite forms anhedral grains and rims on grains of nickeline (NiAs). In this low-temperature gersdorffite PGE are concentrated toward the mineral edges. Sudburyite and gold occur associated predominantly with nickeline. The PGE and gold are now predominantly associated with sulfarsenides that are the controlling factor for their distribution. © 2013 Society of Economic Geologists, Inc. Source

Reston M.S.,African Minerals Inc. | Baker H.T.,SRK Consulting UK Ltd | Elvish R.D.,BE Enterprises | Reardon C.A.,African Minerals Inc. | Young B.J.W.,African Minerals Inc.
IRON ORE 2011, Proceedings | Year: 2011

The Tonkolili banded iron formations (BIF), Sierra Leone, host extensive iron ore deposits which are of economic signifi cance to the seaborne iron ore trade. The deposits are dominated by a strategic JORC compliant mineral resource of 11.6 Bt grading 30.1 per cent Fe comprised of primary magnetite mineralisation in the form of a fresh metamorphosed BIF featuring a uniform mineral assemblage of quartz-magnetite ± ferro-silicate minerals. Pilot plant metallurgical test work has demonstrated that the production of a magnetite concentrate is achievable using the established benefi ciation techniques of magnetic separation and fl otation. The concentrates are high-grade, and suitable for blast furnace or direct reduced iron pellet feed. The major challenge facing the development of such magnetite deposits at industry competitive production rates is the signifi cant capital investment required for process plant and associated infrastructure. Two well-developed weathering zones exist within the deposits, and are associated with the progressive development of a tropical weathering profi le overprinting the primary BIF. These zones feature a near surface hard indurated duricrust up to 60 m thick, and a soft progressively developed saprolite between duricrust and fresh BIF. These zones have been found to be amenable to producing iron ore products including DSO lump and sinter fi nes from the duricrust, and concentrate from the saprolite. Mineral resources suffi cient to support commercial production of such iron ore products were defi ned by an intensive exploration program in 2010. African Minerals Limited has developed a three phase production strategy to progressively selffund the development of the Tonkolili strategic magnetite project by: • commencing a Phase I 12 Mt/a DSO operation in Quarter 4 2011, • increasing production in Phase II to 35 Mt/a with the commissioning of a saprolite benefi ciation plant and associated infrastructure upgrades, and • developing a 45 Mt/a Phase III operation producing high-grade magnetite concentrate. The comparatively low capital and operating costs of a duricrust DSO lump and sinter fi nes operation coupled with its proximity to ground surface make it highly attractive for the generation of early cash fl ow for the Tonkolili project. Revenue from this early production may be used to selffund the subsequent development of phases requiring progressively more signifi cant benefi ciation plant and infrastructure. Source

Davies A.A.,SRK Consulting UK Ltd | Perkins W.F.,Aberystwyth University | Bowell R.J.,SRK Consulting UK Ltd
Geochemistry: Exploration, Environment, Analysis | Year: 2016

Parc mine in north Wales was abandoned after closure in 1963 and spoil heaps were left to erode into the Nant Gwydyr and Conwy River. A storm event in 1964 caused the west slope of the tailings dam to collapse into the river, polluting 11 ha of farmland with lead and zinc. Reclamation work commenced in 1978 and involved reshaping the tailings pile and capping the north and central sections of the site with limestone quarry waste. The north section was also sown with metaltolerant vegetation (Festuca rubra, Argostis tenuis and Trifolium repens). The aim of the study was to understand how different reclamation surfaces affected soil chemistry using GIS. The uncapped south section, whilst having the most heavily polluted soil (74 mg/kg As, 24,000 mg/kg Pb, and 19,000 mg/kg Zn), supported the establishment of patchy but diverse metal-tolerant vegetation (Alnus incana, Fagus sylvatica, Ulex, Sorbus aucuparia). The capped north section had the least polluted soil (19 mg/kg As, 478 mg/kg Pb, and 1400 mg/kg Zn), densely vegetated with a nitrogen-fixing legume (Trifolium repens), and was able to support grazing animals, but remained visually incongruous and failed to support the re-establishment of native vegetation. The central section, which combined capping with native vegetation (Betula pubescens and Quercus petraea), was considered moderately polluted (26 mg/kg As, 3908 mg/kg Pb, and 9000 mg/kg Zn). Zinc was found to be the limiting contaminant for vegetation growth with soil concentrations exceeding 12 000 mg/kg corresponding to areas of bare ground in the south and central sections. Barium was the only element to increase in the capped sections, indicating the limestone quarry waste used to cap the tailings was most likely barium-rich. © 2016 The Author(s). Source

Hatton W.,SRK Consulting UK Ltd | Fardell A.,SRK Consulting UK Ltd
International Journal of Coal Geology | Year: 2012

The coal in Mozambique's Tete province has been known about for a long time, as the artist/explorer Thomas Baines first captured onto canvass a coal outcrop on the banks of the Zambezi in the late 1850s. The first geological works in the Tete province referred to the studies of coal occurrence, and were undertaken by Richard Thornton (1859), a geologist on the Zambezi expedition under Dr David Livingstone and Guyot. However, most of the recent exploration has been conducted to ascertain the economic potential of the coal resources within the region. The majority of these resources are located within remnants of the Ecca Group of rocks, of the Karoo Supergroup, in the Zambezi graben of the Tete province of Mozambique. The coalfield consists of various sub-basins and is considered the largest undeveloped coal province in the world. Amongst others, it forms host to the well publicised Moatize metallurgical and thermal coal deposit, reported to contain 2.4. Gt of coal and located within the Moatize sub-basin.In late 2004, a consortium of companies headed by Brazilian iron-ore miner, Vale, won the right to develop the Moatize coal deposit. Other companies which tendered for this right were BHP Billiton, Rio Tinto and Anglo American. Vale is partnered in this project with American Metals and Coal International (AMCI), a North American coal producer, which owns 5% of the consortium. The consortium bid $122.8. M for the rights to explore and develop the coal deposit.The allocation of the tender award to Vale opened the way for smaller investors, such as the Zambezi Energy Corporation (ZEC) who decided in late 2004 to develop a number of projects within licence blocks in the Zambezi graben. Investment within the region has accelerated rapidly over the last couple of years and the region has seen a number of developments. During this time the authors have helped to develop the potential of new coal resources and have modified the traditional coal resource estimation techniques, such that they can be used for reporting coal resources according to the terminology and guidelines given in the JORC (the Joint Ore Reserves Committee) code (JORC, 2004).The paper describes the complexities of the underlying regional and local resource geology and describes the challenges of producing resource estimates to international standards, such as JORC. © 2011 . Source

Idrysy H.E.,SRK Consulting UK Ltd | Connelly R.,SRK Consulting UK Ltd
Procedia Engineering | Year: 2012

The presentation focuses on the water management aspects of mining projects, from the mine exploration phase, through mine development, to closure and rehabilitation. Based on SRK's water management experience in many mine projects across the globe, we believe that water resources and their management are often not considered early enough in the development of such projects. This often results in risks that could be mitigated easily at the start of the project becoming issues, particularly during the mine's operational phase. The presentation summarizes the critical water aspects that can present significant risk to the development of a mine and highlights the advantages of considering these water management aspects early in the project. It also presents SRK's approach to assessing mine water resources more accurately and how to prepare an effective water management plan to mitigate the risks that can otherwise adversely affect the mine's operational development, safety and productivity. © 2012 The Authors. Published by Elsevier Ltd. Source

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