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By Eder Villarreal

Existen concesiones mineras en estado de prospección o exploración básica para las cuales, debido a que no cuentan con recursos o reserva mineral definidos, es muy difícil establecer un valor. La metodología que aquí se presenta muestra la forma de valorizar dichas concesiones mineras desde el punto de vista de costos y una serie de variables geológicas y económicas. El proceso consiste en calcular un costo base, realizar una evaluación cualitativa sobre la base de 10 variables, asignarle un peso a cada una de ellas y realizar una operación matemática utilizando dos ecuaciones.

Sep 20, 2019

By J. C. Detweiler

THE Jacksonville plant of Humphreys Gold Corp., operating under leases from National Lead Co. and Rutile Mining Co. of Florida, recovers rutile, ilmenite, zircon, and monazite from an ancient beach deposit containing about 2.5 pct of these minerals in combination. The location of the plant is unique, being situated about ten miles from the center of Jacksonville, Fla., surrounded by a thriving suburb. Two four-lane highways pass within 1 ½ miles of the plant. An expressway now under construction will pass over the tailing pile, within 500 ft of the mine office. The elevation at the plant site is approximately 50 ft above sea level. This is one of two mines producing titanium minerals and zircon in Florida. Another mine is also operated by Humphreys at Starke, about 50 miles southeast of Jacksonville. The Jacksonville deposit extends about six miles in a north-south direction, averaging approximately one half mile wide and twenty ft thick. Values begin at the surface over most of its length and ter-

Jan 1, 1952

By D Craw, J Youngson

Recent exploration for mesothermal gold deposits in the Otago Schist has focussed largely on extensions of, or analogies to, the reverse fault-hosted Hyde-Macraes Shear Zone deposit. Abundant normal fault-hosted mesothermal and epithermal vein deposits in the Otago Schist have attracted less attention, largely because they have limited lateral extent and steeper dips. Northwest-striking normal fault-hosted vein sets near Barewood and Hindon in east Otago crosscut schist foliation on the Barewood-Hindon plateau at a high angle along a combined strike length in excess of 20 kilometres. The trend of the vein sets is not linear, but rather contains several right lateral steps. Almost all veins dip steeply to the northeast. Angular discordance between schist foliation and the plateau surface along the trend increases from near zero at the northwest end of the veins to about 30¦ at the southeast end. Crude formation depth estimates decrease from about 7.5 km at the Barewood end of the zone to

Jan 1, 2002

By Camila Luzia Lira Duarte

O processo de pelotização utiliza o combustível sólido com intuito de gerar energia térmica que será transferida para a pelota de forma a alcançar uma queima uniforme. Na usina de Vargem Grande normalmente o antracito é utilizado como combustível sólido. Com objetivo de testar diferentes fontes de combustível sólido, um teste industrial de com coque breeze substituindo o antracito foi realizado. Como o coque breeze possui menor teor de matéria volátil, cinzas ei maior teor de carbono fixo, o consumo de gás natural no forno pôde ser reduzido. Além disto, o coque breeze apresentou um perfil de combustão mais favorável à qualidade da pelota resultando em ganho nos resultados de compressão. Dessa forma, a viabilidade econômica e operacional da substituição do antracito pelo coque breeze foi positiva.

Aug 17, 2017

By S J. Brace

About 180 000 tons of explosives are used annually underground in South Africa. Most is loaded into holes less than 50mm in diameter. 75% is consumed in the gold and platinum mines where holes are between 25 and 4omm in diameter and no more than 3.0m in length. The small amount of explosives per hole with extreme conditions of heat, humidity and seismic activity, make the choice of explosive on safety and technical grounds very important to the success of a blasting operation. Taken together with the fact that many underground precious metal operations are now marginal then the choice of an explosive, when its price is also considered, becomes critical to the very viability of some mines.

Jan 1, 1994

By M Stewart

Alluvial gold deposits in the area studied are preserved on the valley floor and elevated terraces due to a sequence of glacial/interglacial events during Pleistocene and Recent times. Continued regional uplift has overprinted these events. Prospecting by drilling and bulk sampling has demonstrated a complex alluvial gold resource which is now being mined.

Jan 1, 1989

Modem mineral exploration and development takes place within a data-rich context underpinned by a wide range of data acquisition, processing and interpretation technologies. This leads to requirements for consistent and explicit methods by which the relative risks - or success probabilities - of exploration programs can be assessed and communicated. Bayesian risk assessment methods are outlined which provide a starting point for this more rigorous approach to exploration investment.   Effective governance of information technologies becomes a core function of the modem competitive Board. As such it becomes a component of any business audit and any assessment of the quality and success potential of a company. Limited data however suggest that the average Board may be under-represented in this increasingly critical skill area.

Jan 1, 1997

SOME notes on the works of the Electrolytic Refining and Smelting Company of Australia will no doubt be of interest to members of the Institute, more especially as much of the work is new to Australasia. As many of the members who may read this paper have not been in a position to visit works of this kind, and are consequently not thoroughly acquainted with all the operations carried on, the author has taken the liberty, in some cases, to enter into explanation which would otherwise be unnecessary. The works are situated at Port Kembla (New South Wales), about fifty miles south of Sydney, and are approachable both by rail and water. The Government has recently built a low-level jetty upwards of five hundred feet long, and intends installing at an early date an electrically operated portable crane to facilitate the handling of material to and from the boats. This will mean: a considerable reduction in the length of time that boats are laid up at the jetty. There are also under construction two breakwaters, which, when complete, will materially assist shipping operation...

Jan 1, 1910

By Mario Paredes Malca

El presente trabajo describe el sistema experto por circuito de molienda desarrollado en la Concentradora Toquepala, donde se aplica la tecnología del control experto-basada en conjuntos difusos y modelos matemáticos. Las ventajas que presenta la aplicación de los sistemas expertos comprenden el aumento de la capacidad de tratamiento, la disminución del costo de operación y del porcentaje del producto que no cumple las especificaciones. Asímismo, el sistema experto se integra al sistema de control para asistir al operador en la detección de los casos, donde las operaciones se puedan descontrolar, aunque ésta no sea realmente su principal función. Si se le configura y sintoniza correctamente, el sistema experto detecta, diagnostica en forma continua los problemas de operación y aplica modelos matemáticos y estadísticos de optimización, interactúando con un sistema de control DCS o PLC.

Sep 12, 2005

By Saulo Brinco Diniz

O alumínio e suas ligas por apresentarem uma série de vantagens, são largamente utilizados em diversas aplicações. O que mais reduz o campo de sua aplicação é sua baixa resistência mecânica, porém esta pode ser modificada através da adição de determinados elementos de liga e de processamentos termomecânicos adequados. Este trabalho teve como objetivo estudar a evolução microestrutural de uma liga de alumínio 7475-T7351 processada por laminação cruzada, e posteriormente submetida ao tratamento térmico de recozimento a 500ºC para recristalização, com tempos de encharque de 15, 30, 60 e 120 minutos. De acordo com os resultados apresentados, pode-se observar que a completa recristalização ocorreu entre os tempos de 30 a 60 minutos de encharque no tratamento térmico.

Oct 30, 2017

About MAC ? The national organization of the Canadian mining industry ? Mining, smelting and refining of base and precious metals ? Mining of iron ore, diamonds, uranium, oil sands, coal and industrial minerals ? Many associate members ? www.mining.ca

Aug 1, 2013

By A. W. Khair

Laboratory studies indicate that the specimen size influences the compressive strength of coal significantly. In the past, the diameter/height ratio of coal and rock specimens with different geometry and its influence on failure characteristics was discussed (Khair, 1993; Khair, 1994; Khair and Xu, 1994). In the current attempt, tests are designed and carried out under uniaxial condition in the laboratory to investigate the influence of specimen size. Cubical specimens of coal with edge dimension ranging from 5 cm (2 in.) through 20 cm (8 in.) were prepared according to the standards and tested uniaxially. Results show that compressive strength of coal is dependent on specimen size until certain level and later the change in specimen size would not yield significant change in compressive strength. Cubical specimens were chosen for testing because they are not only in close resemblance to underground pillars, but they are also the most stable shape under loading. The failure characteristics of these specimens were analyzed and their applicability to pillar design aspects in coal mines is studied. A detailed analysis of the physical and mechanical properties of the tested coal seam is also presented.

Jan 1, 1996

By Thomas J. DeMull

Development of the Batu Hijau copper project was completed in the fourth quarter of 1999 with the formal handover and start-up of ore processing facilities. The project began in August 1996 when the owner, PT Newmont Nusa Tenggara (PTNNT), awarded an engineering, procurement and construction (EPC)contract to Fluor Daniel (FD) for the development of the project. This included a copper concentrator, port, power plant, town site and infrastructure. PTNNT managed the development of the mine and the procurement of the mine equipment. In 1996, Batu Hijau was the largest mining project ever undertaken. Developing the Batu Hijau Mine was complex. It involved the work of thousands of people in all parts of the world to plan, engineer, procure, fabricate and manufacture equipment, supply and deliver materials and equipment, and build the plant.

Jan 1, 2002

By L. A. Matthews

The embrittlement of the Ti-6Al-4V alloy by hydrogen dosing at elevated temperature has been investigated. Metal coupons were subjected to isothermal treatments in a partial hydrogen atmosphere in the temperature range from 650ºC?950ºC and the degree of embrittlement after treatment was determined by drop-weight impact testing. Embrittlement was found to be inversely related to reaction temperature as a result of the combined effects of greater hydrogen absorption and titanium hydride precipitation at the lower isothermal temperatures. Keywords Titanium, hydrogen embrittlement, impact energy

Jan 1, 2011

By F. Dahl, P. Raleigh, J. Holzhauser, B. Nilsen

Tunnel excavation using tunnel boring machines (TBMs), has become increasingly common in recent years, despite the fact that precise evaluation of certain risks have not kept pace with the use of these machines. One of the risks easily overlooked by Engineer and Contractor alike are the effects of abrasive ground on the costs and schedule of a given project. The impacts of worn and damaged TBM cutter heads have been observed on hundreds of tunnel projects around the world. It would appear that a reliable prognosis of the abrasiveness of soils on a project would be of great importance for designers, clients and contractors alike. Several well acknowledged test and prognosis methods already exist for rock, however there is only very limited knowledge available to describe the abrasiveness of soil and its impact on soft ground TBMs. This paper will examine approaches to this problem and suggest a new approach based on a current project undergoing design.

Jan 1, 2007

At Appin colliery, geological structural analyses and investigations of roof conditions suggest roof failure may be attributed to vectorial stresses acting on underground openings, and inducing movement along inherent discontinuities in the surrounding rocks. Certain complex joint and fracture patterns tend to exhibit the effect of this movement resulting often in local deterioration in natural support.The following conclusions are drawn.1. Roof failure is related to the inherent nature of the roof rocks, the presence of mechanical discontinuities, and the vectorial stresses imposed upon it.2. Roof failure is not necessarily related to the statistically most prominent jointing.3. Colliery development approximately parallel to the direction of the statistically most prominent jointing sometimes results in favourable roof conditions.4. The maximum principal stress is the resultant of those vectorial stresses acting upon a mine opening and may be inferred from roof adjustments to those stresses after mining.5. Statistical analyses of jointing in the mine workings can provide clues to the tectonic force or forces which have been regionally or locally influential.6. There is a probable relationship between mining induced fracturing, jointing, and micro-fractures in quartz grains, within the sediments of the mine roof.

Jan 1, 1970

By M. Mikhaylenko

Rhenium, molybdenum and tungsten are the elements demanded by high-end technologies. These metals are found in process solutions in forms of their oxyanions: ReO4-, MoO42- and WO42-. The later two can exist in forms of iso- and/or heteropolyanions. Basically all three metals demonstrate very similar chemical behavior in aqueous solutions. Unfortunately, in their mineral sources these elements commonly accompany each other, like pairs of rhenium-molybdenum or molybdenum-tungsten. Their economical separation is a challenging task.

Jan 1, 2012

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

A discrete element computer program named DMC-BLAST (Distinct Motion code) has been under development since. 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in two dimensions (2-D). DMC-BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993).

Jan 1, 1998

By Don Phelps, Dean Brox, Peter Procter, Andy Saltis, Tom Morrison, Jeff Pringle

The Greater Vancouver Water District is currently constructing the Seymour-Capilano Water Filtration Project to enhance the quality of drinking water in the Vancouver metropolitan area. The Seymour-Capilano Water Filtration Project comprises the 1,800 million litres per day Seymour-Capilano Filtration Plant, the 1,080million litres per day Capilano Pumping Station, twin tunnels with associated shafts, and the Capilano Energy Recovery Facility. The twin tunnels will convey raw water under pressure from the Capilano Reservoir to the Seymour Filtration Plant and return treated (filtered) water for distribution. The Twin Tunnels component of the project comprises twin, 3.7 m diameter, 7.2 km TBM bored tunnels, the 180 m deep Seymour Shaft as the main launch shaft, and two 4 m diameter, 268 m deep raise bore exit shafts at Capilano. The Twin Tunnels have been planned as predominantly unlined tunnels sited at depth entirely within granitic bedrock and cross under two major buried glacial valleys of breadths in excess of 1500 metres that are filled with glacial sediments to depths up to 200 metres. The maximum overburden along the tunnel alignment is approximately 400 metres. Comprehensive site investigations and studies were completed during the detailed design stage of the project. The construction of the twin tunnels started in the fall of 2004 and is planned to be completed by mid-2008.

Jan 1, 2005

By AIME AIME

EDWIN W. KEMMERER, professor of international finance at Princeton, in a speech before a banking conference at Urbana, Ill., on Nov. 26, stated that the increase in the store of gold held by the United States is not so alarming as it appears on the surface. Excerpts from his address, as reported by The New York Times, follow: "It is significant . . . that the value of gold as expressed in its purchasing power in the United States during the last half-dozen years has been higher than at any other equivalent period since our records began 140 years ago. Our so-called 59-cent dollar today buys about 25 per cent more goods at wholesale than did our old dollar in the prosperous year 1926, and an ounce of gold will now buy considerably more than twice what it did then. This present high value of gold is one reason for its recent large production.

Jan 1, 1941