Ghana Mining Journal最新文献

{"title":"An economic analysis of oil sands mining options","authors":"R. Suglo","doi":"10.4314/GM.V11I1.53273","DOIUrl":"https://doi.org/10.4314/GM.V11I1.53273","url":null,"abstract":"Mining projects normally involve huge levels of capital outlay with their attendant high investment risks. Thus, all new mining projects and existing projects have to be economically evaluated to assess their viabilities and whether they add value to the company’s portfolio. Economic analysis is one of the best tools for evaluating and comparing different projects or investments options. Various economic evaluation criteria such as the Net Present Value, Profitability Index, Internal Rate of Return and Discounted Payback Period are commonly used, alone or in combination, to determine the acceptability or attractiveness of projects and to aid in the selection of the best investment ventures from a number of options. In this paper, economic, risk and sensitivity analyses were conducted on two oil sands mining options at Syncrude Mine in Canada. These are the Current Mining System (CMS) and the Cyclic Excavator Conveyor Belt Control System (CycEx CBCS). The results of detailed economic analysis show that the net present value (NPV) of the CMS option is $3.20 ´ 1010 while that for the CycEx CBCS option is $4.06 ´ 1010. The profitability indices for the CMS and CycEx CBCS options are 19.37 and 43.37 respectively. The internal rates of return of the CMS and CycEx CBCS options were calculated to be 29.02% and 33.37% respectively. Both the CMS and CycEx CBCS options have very short discounted payback periods (≤ 0.27 years). The results of risk characterisation of the two mining options show that there is 85% probability that the NPVs of the CMS and CycEx CBCS options will be greater than $2.69 ´ 1010 and $3.42 ´ 1010 respectively. The results of sensitivity analysis show that the input  variables that significantly affect the NPV in both mining options are the discount rate, production rate, oil price, exchange rate, and the federal and provincial tax rates. In general, changes in input parameters such as discount rate, scheduled mine production capacity and time, price of oil per barrel and total operating costs had lower effects on the NPV of the CycEx CBCS option than the CMS option. The calculated economic parameters together with the results of the risk and sensitivity analyses show that the CycEx CBCS option is more economically viable than the CMS option.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82702988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Tonkolili Iron Occurrence of Sierrra Leone: A Petrological Enigma?*","authors":"K. Adjimah, D. Asamoah","doi":"10.4314/GM.V11I1.53269","DOIUrl":"https://doi.org/10.4314/GM.V11I1.53269","url":null,"abstract":"This paper endeavours to resolve, by petrological and mineralogical interrogations, the apparent puzzle being caused by the different names and classifications that have been assigned to the Tonkolili iron occurrence of Sierra Leone by different authors. The mineralogy and petrography of drill core samples of iron occurrences from Tonkolili district of Sierra Leone are used to investigate the type of iron deposit, its environment of formation and classification. Three main rock types that host the Fe mineralisation have been identified as amphibolites, tuffs and mafic volcanic rocks. The amphibolites which crop out and are mapped on the surface are underlain by tuffs. Two types of tuffs were identified, namely as rhyolitic and crystal tuffs. The mafic volcanic rocks lie underneath the tuffs. The Fe mineralisations occur as bands and lenses in the tuff and are encountered from depths of 120 to 160 m in the drill holes. The Fe mineralisations which are mainly of Precambrian age are chemical sediments, contain about 55 % Fe and occur as mappable bands and lenses that have ironstone layers defining their top and bottom and thus satisfy Kimberly (1978)’s classification as “iron formation”. It is therefore the conclusion of this paper that with the realisation that the primary Fe mineral is magnetite rather than haematite and since there is an intimate association between the volcanic rocks and the Fe mineralisations, the Tonkolili Fe deposits can be classified as an Algoma type of Banded Iron Formation according to the classifications of James (1954) and definition of Cannon et al., (1986).","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77635332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pitwall Stability Analysis-Case Studies*","authors":"M. Affam, K. Allen","doi":"10.4314/gm.v11i1.53270","DOIUrl":"https://doi.org/10.4314/gm.v11i1.53270","url":null,"abstract":"The importance of pitwall stability in design and economy of open pits has been a subject of considerable research in rock mechanics for some time now. Imperceptible slow mass movement has been a secret agent in inducing major pitwall failure. The problem is location specific and is associated with stress development, shear strength, discontinuity orientations and groundwater regimes. This paper therefore sets out to present pitwwall stability analysis in some selected pits within the Birimian environment in Ghana. Several attitude measurements were taken particularly on the footwall and along the slope face of the oxide, transition and fresh (sulphide) rock materials from some selected pits. The geologic data was subjected to the Romana’s Slope Mass Rating (SMR) analytical procedure and the pitwalls monitored through installed prisms. The oxide/ transition zones gave an SMR quantitative value of 43.1 in the footwall and 44 within the hangingwall, indicating a partial stability at 50o. The fresh rock (sulphide) gave a value of 64 in the footwall showing stability at 55o. As usual, the fresh rock was less problematic as indicated by the SMR assessment compared to the oxide and the transition materials. Creep movement was observed to predominate, being nearly 250 mm/day within the oxidised zone but lesser in the transition and fresh rocks. Induced pitwall failure pattern within the Birimian was more of composite failure (ie.,planar and toppling) capable of destabilising several pits if unchecked.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76189170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Symbolism of umat’s emblem, flag and ceremonial mace - conglomeration of the university's essence and aspirations","authors":"M. Annku, D. Mireku-Gyimah","doi":"10.4314/GM.V11I1.53275","DOIUrl":"https://doi.org/10.4314/GM.V11I1.53275","url":null,"abstract":"The University of Mines and Technology (UMaT), Tarkwa was established in November 2004 by Act of Parliament (Act 677) after successfully passing through four exciting levels of erudition. It was concurrently identified by an emblem and a flag as a creditable sovereign institution. On 25th July, 2009 UMaT introduced its first ceremonial mace to be experienced at its first's congregation. This paper brings to the fore the concepts and philosophical dimensions of the emblem, flag and ceremonial mace as unique symbols of UMaT’s erudition, integrity and authority. Part of the concepts are based on studies from traditional and contemporary iconography including Adinkra and Agama traditional symbols for a gratifying symbolic and aesthetic blend. Apart from exploring the cultural background of UMaT, this material is intended to be used as a reference material for educators, historians, and other researchers in related fields and above all preserve UMaT’s rich cultural dimensions.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72671028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The geology of the gold deposits of Prestea gold belt of Ghana","authors":"K. Dzigbodi-Adjimah, D. Asamoah","doi":"10.4314/GM.V11I1.53268","DOIUrl":"https://doi.org/10.4314/GM.V11I1.53268","url":null,"abstract":"This paper presents the geology of the gold deposits along the Prestea gold belt of Ghana to assist exploration work for new orebodies along the belt. Prestea district is the third largest gold producer in West Africa after Obuasi and Tarkwa districts (over 250 metric tonnes Au during the last century). The gold deposits are structurally controlled and occur in a deep-seated fault or fissure zone that is regarded as the ore channel. This structure, which lies at the contact between metavolcanic and metasedimentary rocks in Birimian rocks, is more open (and contains more quartz lodes) at the southern end around Prestea than at Bogoso to the north. The gold deposits consist of the Quartz Vein Type, (QVT) and the Disseminated Sulphide Type (DST). The QVT orebodies, which generally carry higher Au grades, lie within a graphitic gouge in the fissure zones whilst the DST is found mostly in sheared or crushed rocks near the fissure zones. Deposits were grouped into three in terms of geographic location and state of development; The deposits south of Prestea are the least developed but have been extensively explored by Takoradi Gold Company. Those at Prestea have been worked exclusively as underground mines on QVT orebodies by Prestea Goldfields Limited and its forerunners; Ariston and Ghana Main Reef companies until 1998 whilst the deposits north of Prestea, which were first worked as surface mines (on DST orebodies) by Marlu Mines up to 1952, were revived by Billiton Bogoso Gold in 1990. Bogoso Gold Limited, a subsidiary of Golden Star Resources, now runs the mines, which are currently working “Oxide ore” (the oxidised derivate of the DST ore) by surface operations in open cut mines at Bogoso and Prestea. Active exploration is presently underway to find extensions to the orebodies and extend the life of the mines. The summary of the special attributes of the deposits presented in this paper may be useful in re-evaluation of the orebodies.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75132145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluoride in groundwater and its implications in west Gonja District of Ghana","authors":"E. Arhin, M. Affam","doi":"10.4314/GM.V11I1.53272","DOIUrl":"https://doi.org/10.4314/GM.V11I1.53272","url":null,"abstract":"Fluoride levels in groundwater may cause either enamel fluorosis or dental caries depending on their concentrations when consumed. Research has shown that an estimated 60 % of the total intake of fluoride is through drinking water (Selwitz et al, 2007). Boreholes sunk in the West Gonja district had their groundwater analyzed for fluoride. Using World Health Organisation (WHO) standard of (0.5-1. 5 mg/l) as basis, result revealed that concentration deviates from standard set by WHO. Test boreholes drilled in the communities showed three broad categorisations of fluoride levels in the groundwater as; <0.5mg/l (inadequate), 0.5-1.5 mg/l (adequate) and 1.5 – 4.8mg/l (excessive). Generally, the distribution in the district varied between 0.1 to 4.8 mg/l The concentration of fluoride was again spatially analysed to predict areas prone to fluorosis and dental caries diseases. The findings showed that most communities in the district within the western portion had generally low concentrations while those towards the east had elevated levels. The reappraisal of fluoride concentrations in groundwater resulted in the creation of geochemical atlas map of West Gonja District that showed the excessive, adequate and deficient concentrations of fluoride and potential fluorosis or dental caries localities based on the permissible levels.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"84 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83257906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water resources issues in Tarkwa municipality, southwest Ghana","authors":"J. Kuma, E. Ewusi","doi":"10.4314/GM.V11I1.53271","DOIUrl":"https://doi.org/10.4314/GM.V11I1.53271","url":null,"abstract":"Tarkwa is an old and important gold mining town located in a sub-humid tropical climate with its economy built on mining and allied services. The current high gold price has generated a vibrant local economy in Tarkwa and increased its population and water use. Consequently, the water resources of Tarkwa are getting under pressure. Data on the annual ratio of water produced by Ghana Water Company Limited (GWCL) at the Bonsa Treatment Plant (BTP) to population growth of Tarkwa from 1987 to 2008 reveal an amount of 76 litres/person/day in 1987 decreasing to 40 litres/person/day in 2008. These figures show that the amount of water produced over the years has not kept pace with population growth in Tarkwa. Additionally, Unaccounted For Water (UFW) is very high, although it is gradually being reduced from 66 % in 1991 to 34 % in 2007. As a result of the inadequate water provided by GWCL, more than 318 wells have been constructed in Tarkwa. However, most of the wells were constructed without recourse to professional advice and preliminary results have revealed that some are biologically and chemically contaminated while others are at risk of becoming contaminated. Additionally, inadequate waste disposal practices, building on hills and in recharge areas, washing of cars into receiving streams, illegal mining and its processing also into receiving streams suggest that surface and some ground water are being contaminated. A comprehensive water resources management plan in the form of an environmental impact statement including the delineation of groundwater protection zones is recommended to address water issues in Tarkwa. Public education on environmental issues, enactment and enforcement of by-laws arising from this plan should be implemented.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88808148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contract Mining versus Owner Mining - The Way Forward*","authors":"R. Suglo","doi":"10.4314/GM.V11I1.53274","DOIUrl":"https://doi.org/10.4314/GM.V11I1.53274","url":null,"abstract":"Mining involves many operations such as rock breakage, materials handling, equipment maintenance, mine design, scheduling and budgeting. At one stage or the other mine managements often have to decide whether to undertake a major mining operation using their own equipment and personnel or to contract the operation out to a specialised mining contractor. By contracting out one or more of their mining operations, the mining companies can concentrate on their core businesses. This paper reviews contract mining and owner mining to determine the merits and demerits of each and how they affect the economies of the mining companies. The results show that the decision to adopt owner mining or contract mining is influenced by the life of the mine, the availability and use of capital, and that contract mining helps to reduce the cost of mines with short life spans. The general trends in the mining industry show that contract mining will be the way forward for most mines under various circumstances in the future.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"82 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90934405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Some Environmental Issues of Inland Valleys: A Case Study*","authors":"E. Asiam, E. Buaben","doi":"10.4314/GM.V10I1.42808","DOIUrl":"https://doi.org/10.4314/GM.V10I1.42808","url":null,"abstract":"Inland valleys have complex geo-ecological systems and hence biochemical accumulation of heavy metals in soils is inevitable. Such a situation can affect crop physiology and produce quality. This study was therefore carried out to ascertain the extent of heavy metal accumulation in Anum inland valley which fringed a mining concession at Konongo in Ghana. The study revealed that accumulation of heavy metals particularly iron and lead occurred in soils and crops, a phenomenon that can result in reduction of crop quality and yield from such valleys. The concentration of lead in the rice tissue was between 2 mg/kg and 13 mg/kg while that of iron was between 1400 mg/kg and 4500 mg/kg. The study concluded that inland valleys can be real environmental liability because produce from such valleys can be polluted and hence can be a source of social conflict particularly when they fringe mineral concessions as the adverse impacts could be unfortunately attributed to mining activity and similar land uses. Hence, development of a mine in such areas requires a comprehensive environmental impact assessment to ascertain the environmental quality of the adjoining inland valleys to prevent social conflict with the host community.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90920519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Land Use Changes within the Bogoso-Prestea Gold Concession, South West Ghana","authors":"E. Duncan, J. Kuma, S. Frimpong","doi":"10.4314/GM.V10I1.42800","DOIUrl":"https://doi.org/10.4314/GM.V10I1.42800","url":null,"abstract":"Mining activities have existed in the Bogoso-Prestea area for over a century. The high demand for gold has led to intense mining activities in the area and has resulted in land use changes. This study evaluated a total area of 4 379.93 ha within the Bogoso-Prestea Gold Concession that has experienced land use change due to mining using estimation of areas and analysis of land use flows over a period of twenty years ie.1986 - 2006. Results from the study revealed that mining increased in land coverage from 4.69 ha in 1986 to 530.84 ha in 2006, an increase to 12.1% of the study area. Settlements increased to 4.95% in 2006 as compared to 0.41% in 1986, showing a significant rural migration primarily due to mining. Agricultural land use reduced from 97.8% in 1986 to 82.7% in 2006. The study also revealed that land use due to mining increased by only 0.67 % between 1996 and 2006 and if this trend continues, then land use due to mining under the prevailing conditions might not introduce any significant increment between 2006 and 2016.","PeriodicalId":12530,"journal":{"name":"Ghana Mining Journal","volume":"90 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73398317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}