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By John Frostiak, Igor Gonzales, Kenneth G. Thomas, Ken Manning

The Pierina deposit was acquired in August 1996 when Barrick Gold Corporation purchased Arequipa Resources, a junior mining company with extensive land positions in Peru. At the time of acquisition, Arequipa ha.d developed two exploration tunnels and drilled 9 exploration holes on the property. Metallurgical tests, conducted on samples taken from the tunnels and the exploration holes indicated that the ore was amenable to heap leaching. Barrick's exploration team recognised from the outset, the potential of the mineralisation and convinced Barrick's senior management that this was indeed a world class deposit that should be pursued. On November 25, 1998, the fi was poured at Pierina, 27 months from the time of acquisition. During that period BmTick completed its exploration programme, prepared a development plan including capital and operating costs, production profiles and cash flow forecasts, and a schedule to develop a mine and construct a leach pad and gold recovery plant, including all supporting infrastructure. All permits and environmental approvals were obtained and all necessary land was acquired. The project was completed on schedule and under budget. This was the first greenfield mine development for Barrick outside of North America. This paper details, mainly, the research and development, engineering, construction and commissioning of the metallurgical process facilities.

Jan 1, 2000

By O. Guyot, T. Mulpeter

Sadiola Hill mine is located in the sub-Saharan part of Mali. In its first two years of operations, Sadiola Hill mine had already exceeded expectations with respect to profitability, plant capacity, metallurgical recovery, cash costs and social integration into the area. The advanced control system installed by the authors has been a major contributor in the substantial throughput of the mill over the design tonnage with no loss of recovery. The run-of-mine ore at Sadiola consists of soft clays with a varying percentage of grit, producing a high viscosity slurry. The percentage of grit fed to the plant varies on an hourly basis. This combination was expected to have a large impact on the milling circuit and determined that the early installation of an expert mill control system would be advantageous. Svedala Cisa OCS©, was selected as the most suitable support software. The operational rules and control philosophy are housed in the OCS© graphic-oriented fuzzy expert system while a model­based Soft Sensor has the remarkable ability to detect the variations in grit in the feed. Designed during the second half of 1996, commissioning of the system began in March 1997, the OCS was fully on-line by September. With the implementation of the optimising control strategy a throughput of 5.0 million tons relative to the target of 4.4 million tons was achieved for the 1998-operating year. The Sadiola project confirms that advanced process control techniques are among the most cost-and time-effective methods of improving metallurgical plant performance. The recipe that worked at Sadiola is a mix of metallurgical expertise, proper software selection, adequate design of control philosophy, and excellent plant support and follow­up. The early decision, design and installation of the mill control system has resulted in an enhanced Return on Investment.

Jan 1, 2000

By Gordon V. lewis

The Penjom gold mine treats highly preg-robbing carbonaceous ore by using relatively inexpensive gravity and hydrometallurgical methods. The mine is a joint venture between Avocet Gold Limited, a subsidiary of Avocet Mining PLC, a U.K listed mining company with interests in gold and tungsten, and the Pahang State Development Corporation (PKNP) who receive a 2% royalty. The operating team at Penjom embarked on a programme of innovation during 1998 following a realisation that almost all of the primary ore in the gold deposit was highly carbonaceous in nature. Earlier attempts at desliming and leaching the deslimed product through a normal CIL circuit had failed, and through shear necessity, the team turned to new technologies which were considered most suited to the ore characteristics indicated from pre­feasibility testwork. Between April and September, 1998, the mine introduced three key processes, which combined represent the elements of "The Penjom Process". The gravity circuit was boosted to maximise the capture of leachable sulphide and free gold from the relatively carbon free cyclone underflow stream, kerosene and diesel blanking was introduced to treat the cyclone overflow and RIL (resin-in­leach) technology utilised to replace the existing CIL (carbon-in-leach) circuit. Further experimentation with selective resin in partnership with Mintek of South Africa yielded a significant improvement to the process during 1999. Minix­Dowex resin was introduced mid year to replace a non-gold selective resin, which had been used in a flotation/batch leaching circuit for about nine months. Lower carbon levels in the feed at that stage led to the abandonment of flotation and the introduction of continuous RIL, which has been adopted as the major chemical process at the Penjom gold mine since September, 1999. Given the proven performance of the circuit to date, this process may be considered as a low cost option for the treatment of highly carbonaceous ores, particularly those which are not refractory and contain a reasonable percentage of free gold.

Jan 1, 2000

By Scott W. Beckman, Leslie C. Thompson, Joseph A. Kizis

Heap leaching of ore with cyanide is a common and economical means of extracting precious metals (gold and silver) from mined ore. The use of cyanide, and the heap leach process, can seriously impact the environment. In the worst case, catastrophic failure of containment structures can release toxic levels of cyanide into receiving bodies of water, resulting in toxicity to ecological communities and contamination of public water supplies. Furthermore, cyanide degradation products such as nitrates can also impact local streams, lakes, and aquifers. Even if cyanide can be removed, the crushed residual ore may generate acid solutions that can release toxic heavy metals into the environment. Pintail Systems, Inc. (Pintail) of Aurora, CO, in conjunction with technology partners Science Applications International Corporation (SAIC) and Fairmile Gold Corporation (Fairmile), have developed a microbially-based precious metal lixiviant that can be used as an alternative to cyanide. The microbial process, called BioLix, is Pintail's second-generation biotechnology product for the recovery of precious metals from ore. The BioLix process is based on the enzymatic induction of organic lixiviant compounds using proprietary inducing agents and microorganisms. The process operates at near neutral pH and ambient temperatures using non-pathogenic microorganisms and food-grade chemicals. Precious metal extraction is also enhanced through the employment of microorganisms that facilitate mineral-solution reactions such as surfactant generation (improved wettability), and oxidation of gangue minerals that expose mineral surfaces to leaching. In order to demonstrate the effectiveness of the BioLix process, results from laboratory bench-scale experiments and a column study are presented. In addition, new applications for this enabling technology are discussed and include re-leaching of spent ore heaps, in situ leaching, and cyanide replacement for heap leaching.

Jan 1, 2000

By Mike Rhodes, Paul Miller, John W. Neale, Vishal Deeplaul, Barrie Hancock, Tony Pinches

The Beaconsfield underground gold mine is one of only a few new Australian gold projects to come into operation in the current climate of low gold prices. Up to 200,000 tonnes per annum of Tasmania Reef ore will be mined and processed over a minimum eight-year life to a depth of 900 metres below surface. The Tasmania Reef is a gold-bearing quartz-carbonate-sulphide vein occupying an old fault structure which transgresses a series of sedimentary beds. The sulphides are predominantly pyrite with lesser arsenopyrite, and also minor copper as chalcopyrite. Drilling to date below this level clearly indicates that the high-grade orebody is open at depth and that the mine life should be extended significantly over time. Since redevelopment of Beaconsfield mine began in the 1980's, extensive exploration has identified a resource of 1.5 million tonnes within a 450 vertical metre zone beneath the old workings, which extended more than 450 metres below the surface. Installation of an 800 litre per second capacity pump station 180 metres below the surface has been critical in overcoming one of the major hurdles experienced during previous operations in the early 1900's. A multi-stage development program, designed to bring the mine into full production, and incorporating construction of the on-site gold treatment plant incorporating bacterial oxidation, has now been completed. Prior to execution of a detailed engineering design of the Mintek-BacTech bacterial oxidation process, a programme of bacterial oxidation testwork was completed to provide a basis for fixing the process design criteria. A flow diagram of the Beaconsfield treatment plant is shown in Figure l. It comprises:

Jan 1, 2000

By NA NA

Power point slides

Jan 1, 2000

By Arthur P. Chaves, John A. Meech, Vanessa M. Torres

Process choice for a refractory gold ore can become a controversial issue, especially at the early stages of a project. This happens since at preliminary stages, a simple economic comparison among the main process options is not possible as the differences are usually smaller than the precision of estimates. This paper presents a methodology to assess the suitability of each available technologies using a heuristic approach, were technical, economic, operational and environmental aspects are taken into account using a neural network methodology. This methodology is embedded in an expert system for gold ore process design, Intelligold, which is in the final stages of development.

Jan 1, 2000

By MD Cadzow, TW Quaife, DJ Lunt, TS Giraudo

The Macraes Gold Project, operated by Gold and Resource Developments NL, engaged Minproc Limited to assist with the evaluation of a pressure oxidation circuit, this being the key component of a recovery enhancement project. The initial study gave sufficient confidence in the process to enter into project execution. The project is the first to license Newmont Mining Corporation's pressure oxidation technology, which aims to improve gold recovery from the carbonaceous sulfidic flotation concentrate. This paper outlines the fundamental chemistry of the process followed by a description of the plant that was ultimately installed. A summary of the commissioning is given together with an overview of the production results for the first three months of operation. The project ramp-up was rapid, with design temperature and throughput being achieved within days of hot commissioning. Gold recoveries have exceeded expectations and the project has increased the nominal gold output at Macraes from 110,000 oz/y to 150,000 oz/y. Ongoing plant optimisation and problem solving, mainly associated with scale formation, is discussed.

Jan 1, 2000

By Luciano Ramos, Daniel Santos

Igarape Bahia Mine, which is currently the largest gold producer in Brazil, belongs to Companhia Vale do Rio Doce - CVRD and is situated 250 miles south of Belem, state of Para, Brazil. It came into operation in 1992 with the startup of the CIP plant, fed with high grade ore, presently at 3.4gAu/t. The ore is totally oxidized, containing extremely fine particles of free gold. The ore is soft and low cyanide consumer, with a maximum work index of 12kwh/sht. In 1993 a Heap Leaching Plant was set into operation, handling low grade ore of · 1.s g Ault. The Heap Leaching Plant has undergone two major expansions. In 1994 its capacity was raised from lMtpy to 2,2Mtpy and in 1998, with a thorough remodeling of crushing operations, it was raised again to 3.5Mtpy. The CIP plant, which was originally designed with a capacity for l. lMtpy of ore, was expanded to a 2.2Mtpy capacity in 1994. Presently, the CIP plant accounts for most of Igarape Bahia's total gold output, with approximately 220,000oz per year. Igarape Bahia's annual output is around 360.000 oz. Over the last three years, work has been intensified to improve performance of both processes, aiming at maximizing productivity of the two industrial plants. Reduced costs and increased revenues have been given a special emphasis in the unified improvement program. Cost · reduction has involved developing methodologies to rationalize consumption of materials and inputs, while increased productivity has been given top priority as a means of generating increasing revenues. Thus, all of the improvement and development efforts have had a common goal: to increase operating income.

Jan 1, 2000

By Joseph Gambogi

In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of futile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

Nov 26, 1999

By Mahesh C. Jha

Molybdenum, a major refractory metal, is widely used as an alloying element in steels and superalloys to improve their corrosion resistance, physical properties and mechanical strength, particularly at elevated temperatures. The current worldwide production and consumption is estimated at about 130,000 tons contained molybdenum per year. Molybdenum occurs in nature as molybdenite mineral and is recovered by a flotation process as a primary concentrate at molybdenum mines and as a byproduct concentrate at copper mines. The concentrate is roasted to a technical-grade molybdic oxide (tech oxide) in multiple-hearth roasters. About 80 percent of the tech oxide is sold, as such or after conversion to ferromolybdenum, for addition to iron and steel. The remainder is further refined to pure oxide and molybdate chemicals that are used in the manufacture of catalysts, specialty chemicals, molybdenum metal and superalloys. This paper discusses the various steps in the extractive metallurgy of molybdenum, from flotation of sulfide concentrate to reduction of pure oxide to molybdenum metal.

Nov 26, 1999

By Chris Twigge

The paper point out development and successful commercial introduction of new technologies into a metalurgicall. The discussion that follows examines the overall issues of implementation from a management perspectiva and will highlight areas where key success factors are often overlooked. The framework presented is structured around the following key themes: The prime incentive for introducing new technologies is broadly one of economics, the implementation of new technologies is, to a large degree, a process of risk management and although the implementation of new technologies revolves around technical and economic issues, in the end the decisiva factor is people. Proper recognition of the human factors is critical to success. In this sense, the above principles are discussed in the sections that follow and include a number of examples to illustrate how technology can be successfully implementad and how it can fail.

Oct 6, 1999

By Donald Gagnon

El presente trabajo señala el proceso de sostenimiento de terrenos en las minas subterráneas a través del estudio de las condiciones geológicas subterráneas del área, con el fin de establecer distintos tipos de rocas que garanticen la instalación adecuada de las fortificaciones. Asimismo se describen las características y propiedades físicas de los difentes tipos de rocas, como el uso de los distintos pernos para el sostenimiento de roca y sus técnicas de instalación.

Oct 6, 1999

By Francisco Tapia

El presente trabajo describe la importancia de la seguridad minera a lo largo del tiempo y cuál es su visión a partir del tercer milenio. Para ello, revisa los costos y pérdidas en la minería peruana -en tanto afecta la imagen de calidad de nuestro producto por los índices de accidentabilidad que guardan, así como plantea una análisis de la efectividad de los programas de seguridad a futuro. En este sentido, el concepto de "seguridad" con visión para el tercer milenio, implica un control predictivo a los "cuasi incidentes", donde se identifique y evalúe los riesgos antes de que se origine la pérdida, así como resalta la función de la ergonomía de los factores humanos en la administración del control de pérdidas.

Oct 6, 1999

By Juan José Herrera

El presente trabajo señala la importancia de crear un sistema de gestión entre los conceptos de salud, seguridad y medio ambiente en la mina Iscaycruz(Lima) para asi mejorar los niveles de control relativo a estos aspectos, y analizar los sistemas disponibles optados por el sistema integrado sudamericano denominado NOSA. Producto de este sistema de calidad, Iscaycruz logró obtener cuatro estrella NOSA en la primera auditoría y se constituyó como la primera mina peruana subterránea en lograr la certificación internacional de "muy bueno" en Salud, Seguridad y Medio Ambiente. De forma, que la minera está encaminada a ser una operación minera modelo, con una clara concepción de empresa minera segura, limpia y rentable, ética y valores empresariales que consideran la priorización de la salud, seguridad y medio ambiente.

Oct 6, 1999

By Alberto Pacheco

"Generalmente las empresas tiene dos formas de realizar programas de seguridad. Uno de ellos, se enfoca en el trabajado y otro, en el trabajador. El enfoque centrado en el trabajo consiste en eliminar los riesgos físicos en elambiente del trabajo, mientras que el enfoque centrado en el trabajador suele basarse sobre la eliminación de los riesgos psicológicos. En ese sentido, el presente trabajo predente controlar los efectos negativos que afecta los programas de seguridad a través del proceso de observación preventiva de seguridad, de forma que el empleado identifique el comportamiento de lo seguro como parte de sus deseos básicos y asi la seguridad se convierte en sí misma en una meta deseable. "

Oct 6, 1999

By Enrique Zápata

"El presente trabajo describe la influencia de los nuevos métodos y herramientas en la ocurrencia de accidentes incapacitantes que se han registrado durante los últimos años en Milpo. Para ello, se considera las condiciones de terreno y la profundización de la mina, las estadísticas de accidentes capacitantes, la comparación de métodos y resultados, la síntesis comparativa de costo por método, las herramientas nuevas (raise borer, sistema de descarga), tecnología y la exposición al riesgo de accidentes, y la frecuencia lógica de ocurrencia de accidentes. En este sentido, el diseño de nuevas herramientas otorga a los operadores una ubicación panorámica y segura,comodidad y control de un panel de fácil manejo, reduciendo la frecuencia de la frecuencia de ocurrencia de accidentes incapacitantes y fatales."

Oct 6, 1999

By Fernando Bermejo

La compañía minera Raura ha desarrollado una política ambiental donde se busca el cumplimiento de la normativa ambiental a través del uso de la tecnología que comprende los principios establecidos dentro del diseño racional de procesos limpios. En este sentido, el presente trabajo señala las ventajas del uso del diseño del método HERBER, el cual consiste en una adsorción de los iones cromatos en la superficie de la pirita en el circuito de remolienda medios. Asimismo, este no requiere de un pretratamiento condicional, no afecta la recuperación del zinc, mejora el grado del concentrado y la concentración de iones cromatos después del tratamiento está por debajo del límite permisible establecido por el Reglamento de la Ley General de Aguas.

Oct 6, 1999

By Jorge Aguirre Martín

El presente trabajo describe el proceso de optimización y reducción de costos de mina desarrollado por la gerencia en el yacimiento minero de Casapalca. Desde 1998, la gerencia general desarrolló un proceso de reorganización, donde se estableció tres áreas específicas como: la Gerencia General, la Superintendencia técnica y el departamento de Seguridad; así como sus funciones. La primera, comprende el establecimiento de las metodologías de trabajo, la segunda, responde a la implementación de estándares internaciones y la tercera, implementa el sistema de seguridad NOSA para la reducción de accidentes y pérdidas materiales. En ese sentido, el éxito de una empresa radica en valorizar a los empleados como seres humanos, en tanto estos se sientan capacitados y puedan desarrollar sus funciones de manera satisfactoria, con alegría y seguridad, al tiempo que se reducen los costos de operación y se favorece la calidad de la mina.

Oct 6, 1999

By Jaime Arana

El presente texto describe la importancia de trabajar como equipo en la planta de lixiviación de Toquepala y Cuajone. Para ello, se refiere la diferencia entre los conceptos de equipo y grupo. El primero, enfatiza el compromiso, la integración, confianza y interdependencia, mientras que el segundo, desarrolla la desconfianza, independencia, confusión y conflicto. Asimismo, se describe las ventajas y las limitaciones de laborar en equipo, el estilo del líder como la proactvidad, visión, responsabilidad y la comunicación. Finalmente refiere la implementación del trabajo en la división SW-EW, los cambios que se lograron en el nivel de la cultura de la organización, estadística de la fuerza laboral y los sistema de motivación efectiva en el empleador.

Oct 6, 1999