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By T. L. Owen

Since 1993 Cyprus Amax has brought $2.5 billion dollars of greenfield and expansion projects into production, taking it from a mid-sized domestic minerals company into a major international minerals organization. The near simultaneous development of these multiple mineral projects in different locations around the world provided the opportunity for Cyprus Amax to develop a formal project management approach based, in large part, on an outsourcing philosophy. This formal project management system along with its outsourcing philosophy has served the growth agenda of Cyprus Amax extremely well. These preceding factors, coupled with the in-house retention of a core project group that fully understands the breadth of skills and abilities needed to undertake development of multiple large projects successfully, have been the cornerstone of Cyprus Amax’s project development success.

Jan 1, 2000

By Masayuki Ishikawa

In a radio frequency and optoelectoronic device packaging, Gold-Tin (Au-20 wt% Sn eutectic) solder is used widely due to the excellent electrical and thermal conductivity, high strength, and negligible creep characteristic under repetitive thermal cycling. With the recent lead-free movement, Gold-Tin solder is recognized as an alternative material for high temperature Lead-Tin solder. Generally, Gold-Tin solder is supplied in the forms such as ribbons, pellets, and ring frames. However, these forms must be set-up accurately on the joint area to press chips in bonding, therefore, it is difficult for these forms to satisfy the recent requirements for the down sizing in the connection areas. On the other hand, Au-20 wt% Sn solder paste can be applied flexibly to various supplying methods, such as printing, dispensing system and pin transcript. These methods also make it possible to reduce the production cost. However, in the case of using the solder paste, the void issue is one of the most undesirable problems. The void causes the degradation of the characteristics such as the bond strength, electrical characteristic and thermal conductivity. We have been intensifying the development of the void free paste, and have achieved void reduction by optimizing the powder size, the flux composition and the reflow condition.

Oct 1, 2003

By E. V. Lilford

Valuators of mineral properties are faced with a range of valuation methodologies, the most important of which are grouped under the headings of the market approach, the cost approach and the income approach. The way in which value is defined and the detail of the different valuation methodologies is examined here. This paper aims at documenting the variety of valuation procedures and applying each method to a variety of gold projects and comparing the outcomes. Any decision to apply a valuation technique will depend principally on the stage to which the project has been developed. The valuation approach to a greenfield project will be substantially different from that applied to a well-drilled, extensively explored mineral property. Furthermore, a valuation exercise may produce different outcomes for the same gold project depending on which method is applied. In order to investigate the variability in valuation methods and to explore the outcomes of different approaches, a series of five gold projects was analysed. The projects differ in regard to levels of capital application, infrastructural setting, depth below surface, in situ grade, and the stage of development, and were valued using the different methods. The most critical aspect of any valuation is the capacity of the valuer to identify the salient issues and ensure that they are incorporated into the valuation. The danger of simply applying ?black box? solutions to valuation problems without a full understanding of the parameters and the areas of uncertainty is emphasized. The importance of the valuator?s experience, insights into best practice and the ability to recognize and submit to the requirements of compliance within the minerals industry is among the most important characteristics of a valuer.

Jan 1, 2005

By Fabio do Prado Verderano

A partir de corpos de prova de uma chapa de aço baixa liga NBR 6656 grau LNE 26, realizou-se a caracterização microestrutural, levantamento do perfil de dureza ao longo da espessura da chapa, ensaios de tração monotônicos, cíclicos de fadiga e análises fractográficas. Concluiu-se que, nas extremidades da espessura da amostra, o valor da dureza é maior, indicando que quando a chapa foi laminada as superfícies em contato com os rolos de laminação sofreram encruamento, aumentando a dureza nessa região. A microestrutura encontrada e o grau das inclusões presentes na amostra são compatíveis para o material, bem como as propriedades mecânicas monotônicas, que estão de acordo com a especificação. Por meio de ensaios de fadiga de baixo ciclo, encontrou-se uma boa correlação entre as propriedades monotônicas e cíclicas do material para a proposição da equação de Basquin, considerando-se dados seguros, quando utilizado os primeiros vinte ciclos do ensaio de fadiga para estabilização de cada corpo de prova. Verificando-se a seção transversal da fratura do corpo de prova, observa-se que o mecanismo de falha do material ocorreu a partir do aparecimento de trincas na interface ferrita-cementita com propagação transgranular até a fratura final.

Aug 17, 2017

By Kenneth F. Wyman

The following report details the successful construction of Contract 2A of the Three Rivers Water Quality Management Program, Intrenchment Creek Combined Sewer Overflow Conveyance System, in DeKalb County for the City of Atlanta, Georgia. The contract required construction of approximately 2878 m (9443 ft) of tunnel bored to an initial diameter of 7.95 m (26 ft 1 in), with provisions to concrete line those portions designated by the engineer to a finished internal diameter of 6.91 m (22 ft 8 in). Flanking the tunnel are two shafts. The upstream shaft was excavated to a nominal diameter of 4.87 m (16 ft) to accommodate a finished internal diameter of 3.66 m (12 ft). This shaft required a transition boot fully concrete lined to final dimensions of 6.91 m (22 ft 8 in) wide, 13.72 m (45 ft) long, and varying in height from 6.91 m (22 ft 8 in) to 12.80 m (42 ft). Associated work necessary to complete the contractual obligations included installation of 22.86 m (75 ft) of cut-and-cover box culvert, 484 m (1589 ft) of open-cut sewer installation in sizes ranging from 0.30 m (12 in) to 1.68 m (5 ft 6 in), one river crossing, 137.46 m (451 ft) of monolithic concrete trapezoidal channel, and installation of 19125 cu m (25000 cu yd) of select fill material compacted and graded to finished contours. The downstream shaft was excavated to a minimum diameter of 12.04 m (39 ft 6 in) and concrete lined to a finished internal diameter of 10.67 m (35 ft). Requirements here included installation of a complete pumping station with all mechanical, electrical, and structural elements necessary for dewatering the tunnel through the controlled use of four 250 hp submersible pumps discharging into the facilities of the Intrenchment Creek Water Pollution Plant. The objective of this project was to collect combined storm runoff and sanitary flows currently coursing through Intrenchment Creek

Jan 1, 1985

By George L. Richert

The Minas de Matahambre is situated on the north coast of Cuba, in the Province of Pinar del Rio, approximately 150 miles west of Havana. This nine is the only producer of copper in Cuba, and has been worked for the past 15 years. In 1921 the property was affiliated with The American Metal Co., Ltd., and has been worked by them since that time under the direction of Mr. D. D. Homer, General Manager. Extracts from P. D. Wilson's ?Preliminary report on the geology at Minas de Matahambre? have been freely used in this report.

Jan 1, 1929

By W. W. Weller

Thermodynamic values for scandium and its compounds are very sparse. This is evident upon examination of any of the commonly used compilations of thermodynamic data. For example, National Bureau of Standards Circular 5004 lists only four heat of formation values, two free energy of formation values, and four heat-capacity values for scandium compounds. The entropy of crystalline scandium is one of the most fundamental values that has been lacking. This Bureau of Mines paper reports heat-capacity data for scandium metal in the temperature range from 50° to 298° K., together with the entropy value at 298.15° K. derived from these data through application of the third law of thermodynamics.

Jan 1, 1962

By Marcia Harris, Richard Mainiero, Michael Sapko

Since 1988, there have been 17 documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata into occupied enclosed spaces as a result of proximate trench blasting or surface mine blasting. These incidents resulted in 39 suspected or medically verified carbon monoxide poisonings and one fatality. To better understand the factors contributing to this hazard, the National Institute for Occupational Safety and Health (NIOSH) carried out studies in a 12-foot diameter sphere to identify key factors that may enhance the levels of CO associated with the detonation of several commercial trenching explosives. The gaseous detonation products from emulsions, a watergel, and ANFO blasting agents as well as gelatin dynamite, TNT, and Pentolite boosters were measured in an argon atmosphere and compared with those for the same explosives detonated in air. Test variables included explosive formulation, wrapper, aluminum addition, oxygen balance, and density. Major contributing factors to CO production, under these laboratory test conditions, are presented. The main finding is the high CO production associated with the lack of afterburning in an oxygen poor atmosphere. Fumes measurements are compared with the manufacturer’s reported IME fume class and with the Federal Relative Toxicity Standard 30 CFR Part 15 in order to gain an understanding of the relative toxicity of some explosives used in trench blasting.

Jan 1, 2003

By Marco Taipe

Uno de los mayores costos del proceso minero es el de perforación, en tanto emplea aire comprimido. Por tal motivo, la industria minera busca diferentes alternativas para reducir los costos del aire comprimido o eventualmente a través del uso del sistema electro-neumático. Este sistema es de fácil instalación y mantenimiento puesto que se basa en electricidad y agua, reduciendo costos y a su vez mejorando las condiciones de trabajo a través de la versatilidad del presente sistema.

Sep 12, 2011

By Brian W. Stump, David P. Anderson

Identification of seismic events detected under a Comprehensive Test Ban Treaty requires a clear physical understanding of the different types of seismic sources including mining explosions, rock bursts, mine collapse and small, shallow earthquakes. Constraint of the operative physical processes in the source region and linkage to the generation of seismic waveforms with particular emphasis on regional seismograms is needed. In order to properly address the multi-dimensional aspect of data sets designed to constrain these sources, we are investigating a number of modern visualization tools that have only recently become available with new, highspeed graphical computers that can utilize relatively large data sets. The results of this study will provide a basis for identifying important physical processes in the source region that contribute to regional seismograms.

Jan 1, 1995

By S. K. R. Iyengar

This report presents the results of a study to develop optimal designs for light-weight mine roof supports for use in underground coal mines. A load capacity of 196 kN (22 tons) and a height adjustable between 1.829 m (72 inches) and 2.438 m (96 inches) were taken as the design parameters and the design goal was a unit weighing less than 22.3 kg (50 lbs). Three alternative design concepts were explored, viz. mechanical, hydraulic, and hydro-mechanical and a total of 13 designs analyzed in detail. Steel, aluminum alloy and composites were the main potential construction materials investigated for suitability from structural, life, and safety and other considerations. The designs considered most promising for development were: (i) the mechanical screw-pin type using telescopic tubes and a fine adjustment screw thread section (ii) the all-hydraulic type, of steel, aluminum alloy or aramid graphite construction (iii) the hydro-mechanical design using telescopic tubes and a short stroke hydraulic cylinder for fine adjustment It is shown that by using realistic mathematical models for stress and deflection calculations, it is possible to reduce prop weight to the design goal. The analysis presented for all-hydraulic props is applicable to hydraulic cylinders on all mining equipment and similar machinery. This report includes the computer program and user's guide for analyzing hydraulic cylinders as well as a cross-indexed bibliography on structural composites.

Jan 1, 1978

By K Kongolo, M K. Kalenga

It is well known that the electrochemical precipitation of metals from aqueous solutions is conducted by the electrochemical standard potential scale. This scale indicates the order of nobility of different metals. Consequently, the standard potential scale shows the nocivity of metals when they are present as impurities in aqueous solutions containing metals. In the hydrometallurgy of cobalt, nickel and zinc are co-deposited during cobalt electrodeposition. Nickel has almost the same chemical, physical and electrochemical properties as cobalt. Furthermore, the electrochemical potential of nickel is relatively higher than that of cobalt. For this reason nickel is preferentially reduced at the cathode in the presence of cobalt. The presence of small amounts of zinc in solution leads to contamination of cobalt electro won. In spite of its lower electrochemical potential in comparison to cobalt, zinc is reduced on the cathode because of its higher hydrogen-overvoltage. But, in the hydrometallurgy of zinc, small amounts of cobalt present into solution will contaminates the zinc reduced at the cathode. This is easily explained by the fact that cobalt is more electropositive than zinc. The co-deposition mechanism of sulphur at the cathode is not yet well understood. Great attention has to be paid to the mechanism of co-deposition of sulphur during cobalt electrolysis..This work aimed to investigate the influence of some parameters on the co-deposition of nickel, zinc and sulphur during cobalt electrowinning. The following parameters have been investigated : Co2+ concentration in the electrolyte, current density and ammonium sulphate (NH4)2SO4 additions. It has been established that important nickel, zinc and sulphur co-deposition takes place at relatively low Co2+ concentration in solution. The behaviour of these elements with regard to the cathodic phenomena has been established.

Jan 1, 2005

By P Mesquita, A Nolan

Using a scientific-principled definition of global socio-ecological sustainability can be a useful basis for planning precious and base metal mining projects. The mining industry faces key challenges of; viability of the minerals industry; the control, use and management of land; national and local socio-economic development; environmental management; materials stewardship; and access to information. Using a framework for strategic sustainable development to assess the current reality of mine project development has resulted in identifying areas of strength and opportunities for improvement between current best practices and a desired vision of sustainability constrained by science based principles. These gaps indicate opportunities to strengthen current strategies, tools, and actions with a deeper understanding of socio-ecologic systems and a first-order, principled definition of sustainability, enabling success in moving towards achieving a sustainable society, ie sustainability. Evaluation of mine project development and their impacts on ecological and social systems using a systems perspective which recognises the underlying principles of operation, delays, feedback loops and response to change highlight specific opportunities to create value for social, economic and ecologic systems. Envisioning this future for mining projects within a sustainable society can be done by evaluating their development and operations guided by the sustainability principles. Performance indicators play a key role in measuring progress towards achieving sustainability goals yet it is necessary to consider whether indicators capture the whole systems perspective. Connected to this broader view, indicators can contribute much value to the mining industryÆs sustainability journey. This paper examines how current processes for mining projects can be developed using a whole systems perspective and measured using holistically designed performance indicators.

Jan 1, 2009

By William O. Vanderburg

This report3/ gives the reconnaissance of a reconnaissance of the mining districts in Churchill County, Nev., made in the fall of 1938 and spring of 1938 All of the mining districts in the county were visited, but no attempt has been made to include all the mines and prospects within the area; inclusion or omission of a property in this paper has no bearing on its merits, The report gives the situation of the various districts, mineral production, and ownership of properties; describes the ore deposit, mines, and prospects; contains information on past and current activity; and includes other data likely to be useful to those interested in the development of our mineral resources. The various district, were named when they were organized for purposes of record and regulation. When established, the districts embraced large areas n without well- defined borders, so that the names have little geographical significance.

Jan 1, 1940

By John Rajala

The Otjikoto Gold Mill was commissioned during November–December 2014 as Namibia’s first new gold producer in 30 years. Its operations consist of surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and gold recovery. The initial mill design capacity was 2.5 Mt/a. Its capacity was expanded after nine months of operation to 3.1 Mt/a, and process performance has significantly surpassed design expectations. After startup, the Otjikoto Mill’s throughput and gold recovery ramped up quickly, with both parameters exceeding design after only two months of operation. The robust process performance continued into 2019, with key performance indicators (KPIs) eclipsing design values in almost every aspect of mill operation. The Otjikoto Mill’s gold recovery is exceptionally high, exceeding 98 percent every year following startup, especially considering the low-grade nature of the deposit.

By José Cuadros

"El presente trabajo describe la aplicación del ""método gráfico de estabilidad"" como herramienta de diseño en el dimensionamiento de tajeos a través de técnicas geomecánicas que pueden ser aplicadas en otros yacimientos con similares condiciones que la mina Chupa a fin de mejorar la productividad y y mantener adecuadas condiciones de estabilidad de las excavaciones. En consecuencia, el dimensionamiento de los tajeos de Chupa fue uno de los varios trabajos que la Empresa Minera Iscaycruz S.A. realizó para el inicio de la explotación de este yacimiento a través del método de minado “tajeos por subniveles” con la utilización de taladros largos, sostenimiento con cables y relleno cementado. "

Sep 13, 2001

Bacterial leaching represents an unusual problem in biochemical engineering, because the substrate for bacterial growth is not supplied directly, but is a product of another reaction, the leaching of mineral particles. Leaching arises from the bacterial oxidation of ferrous ions to ferric ions, which in turn oxidize the mineral. For the bacterial dissolution of pyrite, these reactions are: [ ] (Y represents a stoichiometric yield factor, and N represents the amount of bacteria.) Equations [1] and [2] represent a cyclic auto-catalytic system since more ferric ions are added to the system with an increase in the extent of leaching.

Jan 1, 2000

There has been disappointingly little development in the analysis of rock slopes in open pit mines over the past 30 years. A brief review of literature shows that the application of numerical stress analysis methods to open pit mine slope stability has become only relatively common in recent times, and that there are as yet no standardized approaches. The lack of development in general, and of robust, standardized approaches in particular, is surprising in view of the ?ultra? deep open pit mines that are being developed to depths in excess of 1000 m. In this paper, the results of a substantial programme of two dimensional and axisymmetric analyses of open pit slopes are described. Variations in the following parameters were taken into account in this programme: slope angle, slope height and horizontal to vertical in situ stress ratio. The evaluation of the data has concentrated on the tensile stresses and the extension strains in the slopes. This is believed to be the first publication dealing with strain distributions in slopes. The occurrence of zones of tensile stress was very limited. These zones occur in the crests of slopes, except in the case of low horizontal to vertical stress ratios, in which case the tensile zone is in the floor of the pit. In contrast, very large zones of extension strain can occur, and this finding represents a significant new aspect in slope stability that has not been considered before. The greatest magnitudes of extension strain occur near the toe of the slope, either in the slope itself, or in the floor of the pit. The magnitudes of the strains are considered to be large enough to result in fracturing of intact rock, and the fracture orientations predicted are adverse for slope stability. The large zone in which such extension failure could potentially occur in a 1200 m deep pit is typically more than 100 m horizontally behind the toe and about 400 m up the face from the toe. Fracturing that is extension in nature is common in competent, brittle rocks and often develops with some violence and little or no warning. Such ?strain bursting? produces easily measurable seismicity, events often being audible as well. In the slope situation, the expected physical manifestation of this behaviour would be popping off of rock slabs and plates of rock from slope surfaces and popping up of the pit floor, as well as the formation of new fractures within the rock mass. Such behaviour may cause overall slope failure, or may initiate failure, which may then be driven to overall slope failure by other influencing factors or combinations of factors. In addition to instability resulting from the fracture surfaces themselves, all induced fracture surfaces could interact with natural geological structures to facilitate formation of a significant failure surface. With suitably orientated joints, extension strains are likely to manifest themselves in the opening up of such joints and hence in the loosening of the rock mass in a preferential orientation, with potential effects on groundwater flow patterns.

Jan 1, 2003

Council for 2002/2003 President S.J. Ramokgopa President-elect T.R. Stacey Vice-presidents Senior F.M.G. Egerton Junior W.H. van Niekerk Immediate Past-president A.A.B. Douglas Honorary Treasurer J.A. Cruise

Jan 1, 2003

By JOHN LANE DYNAN

HE Tonopah Extension property consisted originally of three claims, with an area of 38 acres. In 1902 a shaft, now known as No. 1, was started near the eastern end of the property, close to the Tonopah Mining Co.'s boundary line, in the. andesite cap rock' which covers the ore-bearing formations in the western end of the Tonopah district. A short distance below the 60-ft. level, the orebodies pinched out, although the veins continued. This shaft has not been used since 1916. Before 1910, the production was small, coming mostly from small shoots of high-grade shipping ore. In that : year, the, company started its 30-stamp mill and cyanide plant; the mill was later enlarged to 50 stamps, with a corresponding increase in the cyanide-plant capacity, which brought the capacity of the mill up to 350 .tons per day. The total production of the mine to Oct. 1, 1920, is 871,177 tons of ore, from which was recovered 15,267,216 oz. of silver and 156,241 oz. of gold.' This makes an average recovery per ton of 17.5 oz. silver and 0.179 oz. gold. The average price received for silver since' the beginning of operations is 65.87 c. per oz., and the average value recovered from the ore-'is $15.25. The area of the property has been gradually increased by purchases and consolidations of adjoining ground until it is now 647 acres. A new shaft, known as No. 2, was started in 1912, 1600 ft. west .of No. 1, and in the following year a crosscut on the 750-ft. level of this shaft resulted in the discovery of the. Murray Vein system, from which the greatest prosperity of the mine has come. This vein, with its related veins,

Jan 1, 1921