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By Luis Miguel Panduro Robles

"La aireación forzada busca acelerar la cinética de extracción del cobre en el cobre a través del oxígeno del aire al ion ferroso que se encuentra presente en las soluciones de lixiviación formando el ion férrico; elion férrico formado de esta manera oxida a su vez al cobre metálico (de la calcosita y la bornita) o al azufre (de la covelita primaria o residual) reduciéndose a ion ferroso. El ion ferroso formado se vuelve a oxidar conoxígeno y así continúa el ciclo hasta que todo el mineral sulfurado ha sido oxidado. En ese sentido, el presente trabajo describe las evaluaciones realizadas en Cerro Verde que analizaron el requerimiento de óxigeno en una pila industrial, la determinación del diámetro de orificio óptimo para las tuberías de aireación y el tipo de tubería más adecuado para la aireación."

Jul 31, 2003

By Osvaldo Arce Burgoa

El presente texto describe el proceso de riqueza minerológica de Bolivia a través de su geología y estilos de mineralización. Dentro de el aspecto geológico, el orógeno andino boliviano cubre un 42% del territorio nacional y ocupa más de 2.200 proyectos y minas de plata, estaño, volframio, antimonio, plomo, zinc, cobre, bismuto, oro, etc, mientras que la Llanura Chaco-Beniana, que ocupa el restante 40%, también hospeda depósitos tipo placer de oro y estaño principalmente. En ese sentido, la extensión total de las áreas prospectivas para depósitos metalíferos en el territorio nacional es de aproximadamente 0,5 M de km2, de los cuales más del 60% se encuentra inexplorado. A esto se añade el descubrimiento posterior de quince yacimientos en Bolivia y los estilos variados de mineralización: diseminados de Au-Sb hospedados en sedimentitas, polimetálicos relacionados con intrusiones, polimetálicos vetiformes de tipo “boliviano”, epitermales, epi-porfídicos, skarn, de reemplazamiento de Fe-Cu-Au, exhalativos sedimentarios (SEDES), volcanogénicos en sulfuros masivos (VMS), epigenéticos estratiformes, formación de hierro bandeado (BIF), intrusiones ultramáficas “manteadas”, Mississippi Valley, etc.

Jul 31, 2003

By Reinhold A. Errath

"The paper describes the problem related with contradiction to the development of sag mills, which one are becoming bigger in size almost every year. In this sense, the concentrator plants are being built more and more in remote areas where the power supply and network conditions are not necessarily covering the needs for the operation of such plants. It also illustrates the permissible tolerances in terms of commutation of the powerelectronics, based on already realized installations. Finally the paper gave an overview about the technical impact of a strong versus weak networks."

Jul 31, 2003

By Eduardo Castro

Los minerales provenientes de la mina Socorro y otros tipos de minerales del cuerpo de Uchucchacua son variables en su composición y, por ende, las características de su procesamiento también. Como consecuencia, la metalurgia de la planta varía notablemente con respecto a la calidad del concentrado bulk plomo y plata y al contenido de magnesio en dicho producto. En ese sentido, el problema estriba que en la depresión del magnesio la presencia de la alabandita se ve finamente alterada, como los limos de carbonatos de magnesio presentes en el mineral. Por ello, el presente texto describe el uso del nuevo depresor P-199 en el proceso de control de flotación de los sulfuros de hierro, como parte de los reactivos que controlen la flotación de minerales de manganeso en los circuitos plomo-plata y zinc-plata en la U. P Uchucchacua. perteneciente a la Cía. de Minas Buenaventura S.A.A.

Jul 31, 2003

By Jorge Dueñas

La voladura de rocas es uno de los métodos tradicionales que fragmenta y perfila la nueva geometría del macizo rocoso, especialmente en operaciones mineras a cielo abierto. En esta perspectiva, el presente trabajo describe la importancia de la caracterización del maciso rocoso para lograr un adecuado tamaño de la roca fragmentada y forma de la pila del material, de forma que se alcance una alta eficiencia en las operaciones posteriores. El proceso de fragmentación del macizo rocoso requiere del planeamiento, geotecnia y producción, así como del conocimiento de las propiedades de las rocas, debido a que se producen efectos sobre los cuales hay que tomar medidas para su control.

Jul 31, 2003

By Jorge Medina R.

"Después de dos años de preparación para adoptar un sistema de gestión de calidad de acuerdo con los requerimientos de la norma ISO 9001:2000, la Planta LESDE de Southern Perú Copper Corporation en Toquepalay Cuajone acreditó su sistema de gestión de la calidad a su producto (cátodo de cobre) en la auditoría de certificación. En ese sentido, el presente trabajo señala la aplicación del sistema de gestión de calidad ISO 9001: 2000 en cátodos electrowon en la SPCC a través del diagnóstico, compromiso, planeación, capacitación, documentación, implementación, auditorías internas, preauditoría, certificación, visitas de seguimiento, participación del personal y las optmizaciones esperadas respecto a este tema. Asimismo, es importante integrar la gestión de la calidad en seguridad, salud, y medio ambiente y así lograr la certificación ISO 14001:2000."

Jul 31, 2003

By Scott Elfen

The degree of saturation in leach facilities and waste dumps can be determined by means of this simple test equipment. A design flow rate is applied to the sample, which is equivalent to irrigation and/or the design storm event. In this sense, the paper point out that the tests were carried out on two different ore sizes from the Pierina Gold mine in Peru. The samples were remolded by using three different densities, simulating different depths within the heap. The ore was subjected to a predefined flow rate, which was equivalent to the design irrigation rate. The flow rate was increased to consider the additional effect of the design storm event during irrigation. In the future, further tests will be performed using different ores samples from operating mines and varying different parameters to help built a database and develop other useful applications from this test, such as general guidelines for maximum irrigation rates for leach facilities.

Jul 31, 2003

By Guillermo Velarde F.

El presente trabajo describe el proceso de la conductividad como herramienta de manejo de la aglomeración y la lixiviación en las pilas. En este sentido, dicha conductividad es un recurso necesario de manejo que garantiza la calidad de producto según los requerimientos hidrometalúrgicos. Para ello, se realizó un periodo de aplicación en la S.M. Cerro Verde, cual permitió eliminar las consecuencias de la deficiente aglomeración de entonces. De forma que el criterio de control operativo para el manejo de la aglomeración es mantener el valor de conductividad eléctrica del aglomerado en el rango de 150-180 mA,- aplicable al mineral muy alto o muy bajo en finos o arcillas- y el que garantiza un estándar y deseable calidad, sin segregación en las pilas, etc. En consecuencia, las operaciones mineras con mayores problemas en la permeabilidad de sus pilas por finos o arcillas en calidad indeseable, encuentran bajo este desarrollo, la solución para mejorar su aglomeración, así como el conocer la permeabilidad que tendrá la pila en emplazamiento, se pueda realizar las medidas correctivas.

Jul 31, 2003

1. In 2001, a total of 7,131 sand and gravel mining operations reported employment statistics to the Mine Safety and Health Administration (MSHA). Sand and gravel mines comprised 48.8% of all mining operations, the largest percentage of all mining sectors. Sand and gravel mines are distributed throughout all 50 states. The median number of operator employees per sand and gravel mine was 3.0.

Jul 1, 2003

1. In 2001, a total of 281 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA) (down from 309 metal mines in 2000). Metal mines were the smallest mining sector, 1 comprising 1.9% of all mining operations. This was the lowest percentage of all mining sectors. • The median number of operator employees per metal mine was 17.5.2 • Gold mines comprised 43.1% (n = 121) of all metal mining operations. Other types of metal mines were copper ore (n = 37, 13.2%), iron ore (n = 27, 9.6%), and lead and/or zinc ore (n = 24, 8.5%). • Nearly 20% (n = 55) of metal mines were located in Nevada.

Jul 1, 2003

Jul 1, 2003

1. In 2001, a total of 785 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining operations include the mining of clay, trona, barite, phosphate rock, gypsum, talc, gemstones, and pumice. Nonmetal mines comprised 5.4% of all mining operations.1 • Nonmetal mining operations are located in all but seven states or territories (Alaska, Delaware, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands). • The median number of operator employees per nonmetal mine was 6.1.2 • Mines producing common clay comprised 31.2% (n = 245) of all nonmetal mining operations.

Jul 1, 2003

Jul 1, 2003

By Launa G. Mallett, Jr. Brnich

Overview: The first step to emergency preparedness and maintaining a safe workplace is defining and analyzing hazards. Although all hazards should be addressed, resource limitations usually do not allow this to happen at one time. Risk assessment can be used to establish priorities so that the most dangerous situations are addressed first and those least likely to occur and least likely to cause major problems can be considered later. Purpose: This training package was developed to assist instructors as they (1) determine how to use risk assessment to improve safety preparedness and (2) present risk assessment concepts and tools to trainees. The concepts and tools presented here can be applied to any mine hazard.

Jul 1, 2003

By Benjamin A. Allou

La seule production de columbo-tantalite réalisée en Côte d?Ivoire est effectuée dans les éluvions et alluvions du gisement d?Issia, localisé au Centre- Ouest de la Côte d?Ivoire. Même si un lien direct avec les roches granitiques est suspecté, aucune attention particulière n?a été accordée à l?étude de la minéralisation primaire en relation avec l?évolution des granites et des pegmatites associées. Ces granites, qui sont en intrusion dans les roches sédimentaires du Protérozoïque inférieur, comprennent : le granite orienté à deux micas (Lobo), le granite orienté à muscovite dominante (Bitapia) et le granite porphyroïde non orienté à muscovite dominante (Issia). Les résultats de cette étude indiquent que les pegmatites à Nb-Ta-Be-Li sont liées au granite de type Issia. Les observations de terrain et les analyses sur roche totale des granites montrent que: (1) les trois principaux granites de la région sont de type- S et peralumineux dans leur composition, (2) ils ont été formés pendant la période tardi- à post-Éburnéenne, (3) le granite d?Issia fut le dernier à se mettre en place. Les pegmatites liées au granite d?Issia ont été classées en quatre types : Apegmatites stériles; B- pegmatites à Be; C- pegmatites zonées à Nb-Ta-Be; et Dpegmatites zonées à Be-Nb-Ta-Li. Les pegmatites zonées comprennent les zones suivantes: I- zone à aplite; II- zone graphique; III- zone à albite, microcline, béryl et columbo-tantalite; IV - zone à microcline massive; V- zone à quartz. Ces pegmatites présentent une zone d?altération métasomatique externe. La minéralisation de Ta, Nb et Be est liées à la zone III des pegmatites de types C et D, et celle de Li est associée aux greisens qui peuvent être observés n?importe où dans les pegmatites de type D. Les données de terrain et de laboratoire indiquent que le granite d?Issia est la roche parentale des pegmatites à éléments rares de la région. Les pegmatites minéralisées sont distribuées seulement autour du granite d?Issia et les patrons des terres rares des granites et ceux des pegmatites à éléments rares sont très similaires. Les analyses de la composition totale montrent un lien génétique entre le granite d?Issia et les pegmatites à éléments rares. Il est suggéré que les pegmatites ont été formées durant le transport et la cristallisation fractionnée du magma.

May 1, 2003

By Tom Brady

A major focus of ground control research presently being conducted by the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) is to incorporate weak rock masses (such as are associated with operations in the Carlin Trend in Nevada) into existing design relationships. The original database that led to most of the empirical design relationships presently employed in hard-rock mining was derived from fair-to-good-quality rock. In this study, the relationship between weak rock quality and opening design (nonentry/entry methods) is being investigated. The common factor in all mines is a weak back or wall. This work attempts to provide tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment.

May 1, 2003

By P. W. Jensen

Gold deposits in Interior Alaska are commonly coincident in time and space with reduced, mid-Cretaceous granitoids. The True North deposit of the Fairbanks district is several km from such granitoids, but yields mineralization ages indistinguishable from the Fort Knox granite-hosted deposit. True North, however, resembles sediment-hosted epithermal Au, demonstrating the variability of intrusion-related Au deposits in metamorphic rocks. The True North deposit (14M tons at 1.5 gpt) is hosted within a carbonaceous thrust complex separating eclogite facies from amphibolite facies rocks, located > 5 km from mineralized granite outcrops. The ores contain anomalous Sb, As, and Hg (stibnite is the most common sulfide) with ankerite-sericite alteration in steep NE-striking ?feeder? shears and low angle thrust shears. Nearest hornfelsed rocks are located > 1 km away, and across several high-angle faults. Fluid inclusion data indicates trapping temperatures of ~250C from low-density, low-salinity fluids at P < 0.5 kb. Au was originally present as solid solution in sulfides; minable ores are restricted to the oxidized upper 100 m of the deposit. The considerable differences between this deposit and the temporally equivalent Fort Knox intrusion-hosted deposit indicate no one description adequately characterizes this deposit type.

May 1, 2003

By Serge Vézina

Environmental issues have evolved considerably over the last two decades. The main contributing factors, to name a few, have been the changing values of our modern societies, the globalization of trade and its linkage to environment, evolution and accessibility of information/communication technologies, better educated populations, climate change, long range transport of toxics and the increasing influence of NGOs and multistakeholders. As well, environmental management of mining operations had to be realigned in order to meet these new realities and to respond to more elaborated regulations oriented towards sustainability. Environmental Management Systems (EMSs) have emerged and have been introduced to meet not only the assurance of conformance to regulations but also to prevent pollution and to apply the continuous improvement of mining processes. EMS models have been developed and certification to international standards (e.g. ISO-14 001) is a common practice. Globalization has imposed challenges and additional requirements to environmental management. Developing a mine in emerging countries implies dealing with international agencies, local communities and a variety of government infrastructures to obtain a ?licence to operate?. This paper presents the structure of our EMS and how we have adapted its implementation to our operations in South America.

May 1, 2003

By E. Brouillette

Difficult operating and mining conditions such as low visibility, difficult roadbeds, fast cycling, small openings, and sharp corners create high demand for LHD manoeuvrability and operator dexterity. Operator experience and patience is especially solicited to fill the bucket rapidly and efficiently and performance can be particularly affected by the skill level of individual operators. Teleoperation and automated loading are viewed as options to improve overall equipment and operation performance in certain mining conditions. Comparative statistical measurements of autoloading performance in different production environments at Noranda demonstrate an increase in bucket filling efficiency and a reduction in filling variance, allowing LHD operation to be more consistent and within manufacturer specifications. Consequential cost savings and productivity increases are demonstrated to be transferable to other mining situations.

May 1, 2003

By Kimiz Dalkir

Some things to keep in mind? ! What is your role in knowledge management? ! What knowledge-related challenges are you facing today? ! How does important knowledge get shared in your organization? ! Can you name factors that enable/block innovation and organizational learning in your work context? A brief history of KM? ! Top-down / imposed ! Rigid / bureaucratic ! Slow deployments ! Expensive ! Unpopular: empty libraries, info-junkyards, low adoption rates ! Problems measuring success ! The result: traditional KM is not the answer

May 1, 2003