Kruger G.L.,North West University South Africa |
Grobler A.J.,North West University South Africa |
Holm S.R.,Gold Fields Ltd
Proceedings of the IEEE International Conference on Industrial Technology | Year: 2013
Due to the voltage controlled nature of V/f control it is susceptible to voltage disturbances caused by inverter non-idealities. This paper presents the most common types of non-idealities, along with their usual and improved methods of compensation. By transforming the measured variables to the synchronous reference frame, a static delay compensation which cancels non-ideal cross-coupling at high-speed is presented. Improvement of the DC bus disturbance rejection with a current perturbation control loop is proposed. A less known non-ideality with regard to drives, namely quantization of the duty cycle is presented along with its compensation. Each of the different types of non-idealities and their compensation is verified via simulation. © 2013 IEEE.
News Article | February 23, 2017
TORONTO, ONTARIO--(Marketwired - Feb. 23, 2017) - Cordoba Minerals Corp. (TSX VENTURE:CDB)(OTCQX:CDBMF) ("Cordoba" or the "Company") and its joint-venture partner, High Power Exploration Inc. ("HPX"), a private mineral exploration company indirectly controlled by mining entrepreneur Robert Friedland's Ivanhoe Industries, LLC, are pleased announce that Cordoba has been named to the 2017 TSX Venture 50, a ranking of top performers on the TSX Venture Exchange over the last year. Each year, the ranking showcases TSXV-listed companies that have shown notable results in key measures of market performance. The companies included in the 2017 TSX Venture 50 were selected based on three equally weighted criteria: market capitalization growth, share price appreciation and trading volume. Mario Stifano, President and CEO of Cordoba, commented: "Being named to the TSX Venture 50 is a reflection of the outstanding work by our team of explorationists whose efforts during the past year contributed to a series of notable copper and gold discoveries at our San Matias Project in Colombia. We are aggressively following up on last year's exploration successes at San Matias with three drill rigs testing new high-priority targets." A video produced by the TSX Venture Exchange to mark Cordoba's achievement is available to view at www.tsxventure50.com. Cordoba also was named to the 2017 OTCQX® Best 50, a ranking of top performing companies traded on the OTCQX Best Market in 2016. HPX is a privately owned, metals-focused exploration company deploying proprietary in-house geophysical technologies to rapidly evaluate buried geophysical targets. The HPX technology cluster comprises geological and geophysical systems for targeting, modelling, survey optimization, acquisition, processing and interpretation. HPX has a highly experienced board and management team led by Co-Chairman and Chief Executive Officer Robert Friedland, President Eric Finlayson, a former head of exploration at Rio Tinto, and co-chaired by Ian Cockerill, a former Chief Executive Officer of Gold Fields Ltd. For further information, please visit www.hpxploration.com. Cordoba Minerals Corp. is a Toronto-based mineral exploration company focused on the exploration and acquisition of copper and gold projects in Colombia. Cordoba has a joint venture with High Power Exploration on the highly prospective, district-scale San Matias Copper-Gold Project located at sea level with excellent infrastructure and near operating open-pit mines in the Department of Cordoba. For further information, please visit www.cordobaminerals.com. ON BEHALF OF THE COMPANY Neither the TSX Venture Exchange nor the Investment Industry Regulatory Organization of Canada accepts responsibility for the adequacy or accuracy of this release.
News Article | October 28, 2016
TORONTO, ONTARIO--(Marketwired - Oct. 26, 2016) - Atacama Pacific Gold Corporation (TSX VENTURE:ATM) ("Atacama Pacific") announces that it has made an application the TSX Venture Exchange (the "Exchange") to extend the expiry date of 3,362,500 common share purchase warrant (the "2013 Warrants") that were issued on November 29, 2013. Currently, each 2013 Warrant entitles the holder to subscribe for one Atacama Pacific common share at an exercise price of C$1.40 any time prior to November 29, 2016. Atacama Pacific is applying to extend the expiry date of the 2013 Warrants to March 31, 2018, which extension will be conditional upon acceptance by the Exchange. The expiry date of 637,500 2013 Warrants owned by Atacama's officers and directors will not be extended. Atacama Pacific also announces that it has entered into an agreement to option one of its non-core properties, the Anocarire property, to a company controlled by one of Atacama Pacific's directors, Paul Champagne. The option agreement calls for payments of (i) US$50,000 by September 30, 2016 (paid); (ii) US$150,000 by September 30, 2017; (iii) US$800,000 by September 30, 2018; and (iv) US$4,000,000 by September 30, 2018 (half of which is payable in shares of the optionee at its option). Atacama Pacific will retain a 1% net smelter royalty on any minerals produced from the property. As previously reported, Gold Fields Ltd., having fulfilled the conditions of its agreement with Atacama Pacific, has exercised its option and acquired the Pircas Gold Project located approximately 15 kilometres from its Salares Norte development project. Atacama Pacific now holds a 1.25% net smelter royalty on any minerals produced from the property. Atacama Pacific is currently reviewing development options as it prepares to commence a feasibility study for the Cerro Maricunga Oxide Gold Deposit, with the goal of reducing initial capital costs through the elimination of the secondary and tertiary crushers, by using valley fill leaching at a location closer to the open pit and by commencing operations at a lower production rate of approximately 40,000 tonnes per day over the first years of production, ramping up to 80,000 tonnes per day. Further, the Cerro Maricunga feasibility study will take into account the positive impact of the current economic conditions on operating costs such as lower consumables (power, lime, etc.), stronger United States currency, and potentially lower equipment leasing costs. Maria Leticia Conca Benito, Mining Engineer, Universidad de Chile, Registered Member of Chilean Mining Commission, CEO and Project Director, Alquimia, was the independent qualified person, as defined by NI 43- 101, responsible for the compilation of the information and preparation of the overall 2014 Prefeasibility Study (the "PFS"). Carlos Guzmán, a mining engineer, Fellow of the Australasian Institute of Mining and Metallurgy and a registered member of the Chilean Mining Commission, was the independent qualified person responsible for the mining related sections of the 2014 PFS including the generation of the pit shell for constrained resources and the mineral reserve estimate. Atacama Pacific's business is the acquisition, exploration and development of precious metals resource properties in Chile. Atacama Pacific's principal mineral property is the Cerro Maricunga oxide-associated, breccia-hosted gold project, located in Region III, 140 kilometres by road northeast of the city of Copiapo. Atacama Pacific's goal is to become a producer of gold through the development of the Cerro Maricunga Gold Project. The Cerro Maricunga oxide gold deposit hosts total Proven and Probable mineral reserves of 294.4 million tonnes grading 0.40 grams per tonne for 3,743 million ounces of gold representing one of the largest undeveloped oxide associated gold deposits in the world not controlled by a producer. This news release contains forward looking statements, including predictions, projections and forecasts. Often, but not always, forward looking statements can be identified by the use of words such as "plans", "planning", "expects" or "does not expect", "continues", "scheduled", "estimates", "forecasts", "intends", "potential", "anticipates", "does not anticipate", or "belief", or describes a "goal", or variation of such words and phrases or state that certain actions, events or results "may", "could", "would", "might" or "will" be taken, occur or be achieved. Forward looking statements involve known and unknown risks, future events, conditions, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, prediction, projection, forecast, performance or achievements expressed or implied by the forward looking statements. Such factors include, among other items, the timing of the completion of the update 2014 PFS or feasibility study, the impact of proposed updated mining conditions, including crushing and processing methods and mining rates, the results of due diligence activities, changes in economic parameters and assumptions, the interpretation and actual results of current exploration activities; changes in project parameters as plans continue to be refined; the results of regulatory and permitting processes; future prices of gold; possible variations in grade or recovery rates; failure of equipment or processes to operate as anticipated; labour disputes and other risks of the mining industry; the results of further economic and technical studies, delays in obtaining governmental approvals or financing or in the completion of exploration, as well as those factors disclosed in Atacama Pacific's publicly filed documents. Although Atacama Pacific has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in forward looking statements, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. There can be no assurance that forward looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward looking statements. Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
News Article | November 10, 2016
TORONTO, ONTARIO--(Marketwired - Nov. 10, 2016) - Cordoba Minerals Corp. (TSX VENTURE:CDB)(OTCQX:CDBMF) ("Cordoba" or the "Company") announced today that High Power Exploration Inc. ("HPX"), a private mineral exploration company indirectly controlled by mining entrepreneur Robert Friedland's Ivanhoe Industries, LLC, has completed Phase two of the Joint Venture Agreement ("JV Agreement") and has now earned a 51% interest in the San Matias Copper-Gold Project ("San Matias", or "San Matias Project") in Colombia. HPX has earned its 51% interest in the project by spending a cumulative total of C$19 million in exploration expenditures. Phase Three of the Joint Venture Agreement has now commenced. HPX can increase its ownership in the San Matias Project to 65% by completing a Feasibility Study on the project. Mario Stifano, President and CEO of Cordoba, commented: "We are pleased that our partner HPX has committed to moving the highly prospective San Matias Copper-Gold project to the feasibility stage as we continue with our aggressive exploration program." The San Matias Copper-Gold Project comprises a 20,000-hectare land package on the inferred northern extension of the richly endowed Mid-Cauca Belt in Colombia. The project contains several known areas of porphyry copper-gold mineralization, copper-gold skarn mineralization and vein-hosted, gold-copper mineralization. Porphyry mineralization at the San Matias Project incorporates high-grade zones of copper-gold mineralization hosted by diorite porphyries containing secondary biotite alteration and various orientations of sheeted and stockwork quartz-magnetite veins with chalcopyrite and bornite. The copper-gold skarn mineralization at Alacran is associated with stratabound replacement of a marine volcano-sedimentary sequence. The nature of mineralization encountered at San Matias is similar to other large high-grade copper-gold deposits. HPX is a privately owned, metals-focused exploration company deploying proprietary in-house geophysical technologies to rapidly evaluate buried geophysical targets. The HPX technology cluster comprises geological and geophysical systems for targeting, modelling, survey optimization, acquisition, processing and interpretation. HPX has a highly experienced board and management team led by Co-Chairman and Chief Executive Officer Robert Friedland, President Eric Finlayson, a former head of exploration at Rio Tinto, and co-chaired by Ian Cockerill, a former Chief Executive Officer of Gold Fields Ltd. For further information, please visit www.hpxploration.com. Cordoba Minerals Corp. is a Toronto-based mineral exploration company focused on the exploration and acquisition of copper and gold projects in Colombia. Cordoba has a joint venture with High Power Exploration on the highly prospective, district-scale San Matias Copper-Gold Project located at sea level with excellent infrastructure and near operating open-pit mines in the Department of Cordoba. For further information, please visit www.cordobaminerals.com. ON BEHALF OF THE COMPANY Neither the TSX Venture Exchange nor the Investment Industry Regulatory Organization of Canada accepts responsibility for the adequacy or accuracy of this release. This news release includes certain "forward-looking information" within the meaning of Canadian securities legislation. Forward-looking statements include predictions, projections and forecasts and are often, but not always, identified by the use of words such as "seek", "anticipate", "believe", "plan", "estimate", "forecast", "expect", "potential", "project", "target", "schedule", budget" and "intend" and statements that an event or result "may", "will", "should", "could" or "might" occur or be achieved and other similar expressions and includes the negatives thereof. All statements other than statements of historical fact included in this release, including, without limitation, statements regarding the potential of the Company's properties are forward-looking statements that involve various risks and uncertainties. There can be no assurance that such statements will prove to be accurate and actual results and future events could differ materially from those anticipated in such statements. Forward-looking statements are based on a number of material factors and assumptions. Important factors that could cause actual results to differ materially from Company's expectations include actual exploration results, changes in project parameters as plans continue to be refined, future metal prices, availability of capital and financing on acceptable terms, general economic, market or business conditions, uninsured risks, regulatory changes, delays or inability to receive required approvals, and other exploration or other risks detailed herein and from time to time in the filings made by the Company with securities regulators. Although the Company has attempted to identify important factors that could cause actual actions, events or results to differ from those described in forward-looking statements, there may be other factors that cause such actions, events or results to differ materially from those anticipated. There can be no assurance that forward-looking statements will prove to be accurate and accordingly readers are cautioned not to place undue reliance on forward-looking statements which speak only as of the date of this news release. The Company disclaims any intention or obligation, except to the extent required by law, to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.
Manzi M.S.D.,University of Witwatersrand |
Durrheim R.J.,University of Witwatersrand |
Durrheim R.J.,South African Council for Scientific and Industrial Research |
Hein K.A.A.,University of Witwatersrand |
King N.,Gold Fields Ltd
Geophysics | Year: 2012
Inrushes of ground water and the ignition of flammable gases pose risks to workers in deep South African gold mines. Large volumes of water may be stored in solution cavities in dolomitic rocks that overlie the Black Reef (BLR) Formation, while there are several possible sources for methane, namely, coal seams, kerogen found in some gold ore bodies, or methane introduced by igneous intrusions. Potential conduits that may transport water and methane to underground workings were mapped using 3D reflection seismic data. Edge detection attributes successfully identified many faults, some with displacements as small as 10 m. Faults that displace the Ventersdorp Contact Reef (VCR) and the BLR horizons were of special interest, as known occurrences of fissure water and methane in underground workings show a good correlation with faults that were imaged on the VCR and BLR horizons. Because there are uncertainties in determining the linkage of faults with aquifers and methane sources, it is considered prudent to assume that all structures that displace the VCR and BLR horizons are potential conduits. © 2012 Society of Exploration Geophysicists.
Manzi M.S.D.,University of Witwatersrand |
Gibson M.A.S.,High Power Exploration |
Hein K.A.A.,University of Witwatersrand |
King N.,Gold Fields Ltd |
And 2 more authors.
Geophysics | Year: 2012
As expensive as 3D seismic reflection surveys are, their high cost is justified by improved imaging of certain ore horizons in some of the Witwatersrand basin gold mines. The merged historical 3D seismic reflection data acquired for Kloof and South Deep mines forms an integral part of their Ventersdorp Contact Reef mine planning and development programme. The recent advances in 3D seismic technology have motivated the reprocessing and reinterpretation of the old data sets using the latest algorithms, therefore significantly increasing the signal-to-noise ratio of the data. In particular, the prestack time migration technique has provided better stratigraphic and structural imaging in complex faulted areas, such as the Witwatersrand basin, relative to older poststack migration methods. Interpretation tools such as seismic attributes have been used to identify a number of subtle geologic structures that have direct impact on ore resource evaluation. Other improvements include more accurate mapping of the depths, dip, and strike of the key seismic horizons and auriferous reefs, yielding a better understanding of the interrelationship between fault activity and reef distribution, and the relative chronology of tectonic events. The 3D seismic data, when integrated with underground mapping and borehole data, provide better imaging and modeling of critical major fault systems and zones of reef loss. Many faults resolve as multifault segments that bound unmined blocks leading to the discovery and delineation of resources in faulted areas of the mines. © 2012 Society of Exploration Geophysicists.
Glynn J.R.,London School of Hygiene and Tropical Medicine |
Murray J.,National Institute for Occupational Health |
Murray J.,University of Witwatersrand |
Nelson G.,National Institute for Occupational Health |
And 3 more authors.
Journal of Infectious Diseases | Year: 2010
Background: The rate of recurrent tuberculosis disease due to reinfection, compared with the incidence of new tuberculosis, in those with and without HIV infection is not known. Methods: In a retrospective cohort study of South African gold miners, men with known dates of seroconversion to HIV (from 1991 to 1997) and HIV-negative men were followed up to 2004. Rates of tuberculosis recurrence >2 years after the first episode were used as a proxy for reinfection disease rates. Results: Among 342 HIV-positive and 321 HIV-negative men who had had≥1 previous episode of tuberculosis, rates of recurrence were 19.7 cases per 100 person-years at risk (PYAR; 95% confidence interval [CI], 16.4-23.7) and 7.7 cases per 100 PYAR (95% CI, 6.1-9.8), respectively. The recurrence rate did not vary by duration of HIV infection. Recurrent pulmonary tuberculosis rates >2 years after the first episode were 24.4 cases per 100 PYAR (95% CI, 17.2-34.8) in HIV-positive men and 4.3 cases per 100 PYAR (95% CI, 2.2-8.3) in HIV-negative men, compared with incidence rates of new pulmonary tuberculosis of 3.7 cases per 100 PYAR (95% CI, 3.3-4.1) in HIV-positive men and 0.75 cases per 100 PYAR (95% CI, 0.67-0.84) in HIV-negative men in the same cohort. Conclusions. Tuberculosis recurrence rates, likely due to reinfection, were much higher than incidence rates. The findings suggest heterogeneity in susceptibility, implying that a vaccine could still provide useful protection in the population and strengthening the case for secondary preventive therapy COPY RIGHT: 2010 by the Infectious Diseases Society of America.
News Article | February 15, 2017
VANCOUVER, BRITISH COLUMBIA--(Marketwired - Feb. 10, 2017) - First Cobalt Corp. (the "Company") (TSX VENTURE:FCC) is pleased to announce that effective immediately Ross Phillips has been appointed as a director of the Company, and Ian Stalker has been appointed as an advisor to the board of directors. Kevin Ma, Interim Chief Executive Officer of the Company, noted that, "The addition of Ross and Ian will be instrumental as the Company continues to evaluate additional international asset acquisitions." Mr. Phillips has over a decade of experience in the resource and energy sectors, much of which has involved working on large-scale capital projects with Sherritt International Corporation. From 2009 to 2011, Mr. Phillips was Senior Manager, Financial Analytics and later Director of Business Development at Capital Power Corporation, one of Canada's largest power generation companies. Prior to that time, from 2003 to 2009, Mr. Phillips held various senior roles at Sherritt International Corporation, a diversified resource company that produces thermal coal, nickel, cobalt, oil and electricity. Mr. Phillips currently serves as Chief Operating Officer and Chief Financial Officer of Potash Ridge Corporation. Mr. Stalker is an international mining executive with 40 years of experience in mine development and operations in Europe, Africa and Australia. Mr. Stalker was the Chief Executive Officer of UraMin Inc., a London-listed and Toronto-listed uranium company, from July, 2005, until its $2.5 billion acquisition by Areva in August, 2007. Mr. Stalker was a vice-president of Gold Fields Ltd., the world's fourth-largest gold producer, where he spent considerable time on the ground on its international operations. Mr. Stalker has held executive positions in some of the largest mining companies in the world and has successfully managed eight mining projects through feasibility study, development and construction phases. Mr. Stalker has significant cobalt experience gained during his time on the Zambian Copperbelt from 1973 to 1987. Mr. Stalker operated the country's only dedicated cobalt process plant and was involved in the design and construction of the plant, which is still in operation. Additionally, he was the Chief Executive Officer of the Luanshya Mine from 1999-2000, after its 1997 privatization, where the bulk of the cobalt production from the Copperbelt was centered. Mr. Stalker is currently the Chief Executive Officer of K92 Mining Inc., a gold producer with assets in Papua New Guinea. The Company is focused on developing its existing portfolio of mineral properties and concurrently growing shareholder value through the acquisition of assets in the strategic metals sector, with a particular focus on cobalt projects. On behalf of the Board, Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
Assibey-Bonsu W.,Gold Fields Ltd
Journal of the Southern African Institute of Mining and Metallurgy | Year: 2016
This paper constitutes a write-up of the first Professor Danie Krige memorial lecture in 2014, which was organized by the University of the Witwatersrand in collaboration with the Southern African Institute of Mining and Metallurgy (SAIMM) and the Geostatistical Association of Southern Africa, at which his wife, Mrs Ansie Krige, the SAIMM, and Professor RCA Minnitt also spoke. The memorial lecture was presented by his previous PhD graduate student, Dr Winfred Assibey-Bonsu. During that inaugural memorial lecture, the SAIMM highlighted three activities that the Institute would undertake going forward, so as to remember this great South African mining pioneer: The publication of a Danie Krige Commemorative Volume of the SAIMM Journal An annual Danie Krige Memorial Lecture to be facilitated by the School of Mining Engineering at the University of the Witwatersrand The annual award of a Danie Krige Medal. What follows is both a tribute to his work and a testimony to the great man's deep personal integrity, belief in family, humility, and faith in Christ: all of which led him to become a giant not only in the South African mining industry, but indeed worldwide. © 2016 The Southern African Institute of Mining and Metallurgy.
News Article | November 11, 2016
NEW YORK, November 11, 2016 /PRNewswire/ -- In today's pre-market research, Stocks-Callers.com draws attention back to some Gold equities, namely: IAMGOLD Corp. (NYSE: IAG), Eldorado Gold Corp. (NYSE: EGO), Gold Fields Ltd (NYSE: GFI), and McEwen Mining Inc. (NYSE: MUX). In early...