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By Harrie van Dijk

Feeding laterite nickel slurry into high pressure acid­leach (HPAL) autoclaves in an aggressive environment with slurries heated up to 200°C requires a special pump design. For decades the GEHO piston diaphragm pumps have been used for autoclave feeding at gold ore pressure oxidation plants with slurries up to l 77°C. Lessons learned from these installations have been instrumental in designing second generation feed pumps for processing laterite nickel with operating temperatures of 200°C and a flow rate of 400 m3/h. The Australian nickel industry is using momentarily 8 GEHO positive displacement piston diaphragm pumps. For this application six GEHO ZPM 900 "dropleg" pumps have been supplied to the Murrin Murrin project and two to Bulong.

Jan 1, 2000

By Dan Mackie

Since the production prototype continuous vat leaching pilot plant was installed at Ariel Resources in Costa Rica in 1995, the test results and lessons learned have been invaluable in plotting the future of this method. Vigorous test programs in base and precious metals as well as design developments for studies have shown the advantages, economically, technically, and environmentally that favor this method over current practices in heap leaching and stirred tank leaching. Much larger individual vats have been developed with throughputs as high as 5000 t/d with larger vats envisaged, and there has been a trend towards using vats with ground ore. Five projects are slated to begin detailed engineering this year, three in precious metals and two in copper. Of particular interest to future producers is the ability to deposit d,y, detoxified tailings at a fraction of the cost of conventional methods. Proprieta,y work is ongoing which promises to eliminate the need for tailings dams when using other methods of processing such as flotation. This is of particular importance in light of dam failures around the world in recent years.

Jan 1, 2000

By Frederick W. DeVries

The following charts were presented at the Randol Gold & Silver Forum 2000, held at the Hotel Vancouver (Vancouver, B.C.) from April 18-21, 2000. It must be borne in mind that the "facts" stated and con­clusions drawn by the author were not as the result of a rig­orous technical investigation, but rather as a member of a journalistic team seeking a rapid view for presentation as news to a TV audience. Since the author's visit, some retrenchment on the part of the operators on estimating the cyanide content of the spill seems to have occurred. This does NOT alter the conclusions that (a) the spill was an intolerable embarrassment for the world mining industry, nor (b) the potential damage to future mining investments, should prompt action not be taken: 1. to understand the reasons for the dam failure, and 2. to draw up firm concepts of how to avoid future fail­ures of dams at mining properties containing materials that are toxic, environmentally unfriendly, or with as highly dis­comfiting a profile as cyanide.

Jan 1, 2000

By Jim Smith, Jeff Hudreth, John White

Jan 1, 2000

By Carl-Henrik Knudsen, Rolf Tore Arnesen, Eigil R. Iversen

Recovery of iron and copper from acid mine drainage was studied in pilot scale at a continuous treatment plant at the mine site of the King's mine in Roeros, Norway. The average load on the plant was 1 m3/h. The process tested in this project is a three-step process consisting of: 1) Fe(OH)3 precipitation at pH 3.5, dewatering of iron sludge and transport to ferric chloride plant; 2) after filtration precipitation of residual metals at pH 9, concentration of metal sludge by flotation; 3) extraction of metals from the sludge with sulphuric acid followed by recovery of copper by electrolysis. The copper could be used for local production of different crafts, but this condition needs a further evaluation. The process economy at a full scale plant is evaluated.

Jan 1, 2000

By T Casten

Freeport IndonesiaÆs DOZ (Deep Ore Zone) mine is scheduled to commence production in the second half of 2000. The DOZ will produce 25 000 tpd using mechanised block cave mining methods and will have a number of major improvements when compared to previous block cave mines in the district. The DOZ will have an independent and improved ventilation system, a flexible and efficient truck haulage system, and a more reliable crushing and conveying system than in previous underground mines in the district. This paper will describe the mine plan, haulage, and ventilation systems, and compare them to those used in other operations in the district.

Jan 1, 2000

By C DahnTr-Lindqvist

The Kiruna mine produced about 19 Mt processed iron ore in 1999 using sublevel caving. General failure in the hangingwall has been widely studied and its mechanism is rather well understood. Failure in the footwall is more recent and not perfectly explained. Plane shear failure and Hoek and BrayÆs circular failure charts were successfully used to match the first surveyed failure surfaces. The footwall is not free yet but covered by a caved waste rock abutment whose exact behaviour is poorly known. Based on new field data and numerical models (FLAC), the following paper presents recent improvements in understanding the Kiruna mineÆs footwall failure process.

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 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 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 Fernando Altamirano

El presente trabajo refiere la prevención de incendios en los campamentos mineros metalúrgicos a través de un programa de formación de brigadas. Los principales objetivos del programa son identificar los riesgos de incendio para asi corregir las condiciones inseguras mediante las inspecciones de rutina, aplicar los medios de control y extinción de fuegos de que disponga el minero y la educación al personal en la prevención de incendios para adiestrarlo en la respuesta inicial y calificada.

Oct 6, 1999

By J. B. Greenwood

The paper point out some reasons why contract mining should not achieve the same success in Latin America as it has in Australia. In this sense, any reasons are: the size of operation, mining industry employees bonus scheme, the privatization of nationalized mining assets, general sales tax and the mining unions. Therefore, great deal depends on the attitude or "mindset" of a company's employees. lt is strongly my view that the attitude with which a contractor approaches a job will give rise to a superior mindset amongst its employees when comparad to those from most mining companies. The value of this cultural difference is significant and should never be underestimated. lmportantly, it doesnot only manifest itself in a more productive workplace: it is invariably the case in Australia that the safety achievements of contract miners are superior to those generally expected from the mining industry at large.

Oct 6, 1999

By Fathi Habashi

Extraction by organic solvents is a chemical process in which metal species in the aqueous phase react with an organic reagent to form an organometallic com- plex, thus, the metal species leave the aqueous phase and enter the organic phase from which it can be stripped back in the aqueous phase to obtain a pure and a concentrated solution. The metal in the organic phase is not bound to carbon atoms as in organometallic compounds but to oxygen, nitrogen, sulphur, or hydrogen by a co-ordination (dative) bond (Habashi, 1999).Solvent extraction was used for the first time in hydrometallurgy in connec- tion with the special and urgent materials requirements of nuclear energy during World War II. A plant was constructed in the United States for the preparation of high-purity uranyl nitrate solution. In this plant, the yellow cake (a high-grade sodium or ammonium uranate) was dis- solved in HNO,, and uranium was selec- tively extracted by ether then stripped by water to give a concentrated solution of pure uranyl nitrate. This was gradually followed by developing methods for other high-priced metals such as plutonium, thorium, niobium, tantalum, zirconium, hafnium, boron, beryllium, and molybde num. The second step took place in the 1960s when solvent extraction was applied for the first time to extract a rela- tively cheap metal-copper. At present, solvent extraction technology is wide- spread, well accepted, and highly efficient. Solvent extraction had its origin in the discovery, by Christian Friedrich Bucholz (1770-1818) in 1805, that uranyl

Sep 1, 1999

By Alexis M. Herman

It?s school vacation time again, and kid?s thoughts turn from textbooks and term papers to fun and play, includ­ing outdoor adventures. Old quarries can become swimming holes on hot summer days; sand and gravel piles look like interesting playgrounds; aban­doned mine shafts beckon explorers. But, for the unaware, all three mean danger. Already this year we have seen two stark reminders that mines and minors don?t mix. In Oklahoma, a 13-year-old girl drowned while swimming with friends in an inactive strip mine. In Maryland, a six-year-old boy playing on a quarry site, plunged more than 100 feet to the bottom of the quarry. Playing at such sites may seem like harmless fun, but every year dozens of children and adults are seriously hurt or fatally injured while playing on active and abandoned mine property. These accidents sometimes happen in traditional mining areas like the coal fields of Appalachia and the remote areas of the west. But the threat is anywhere there are active or abandoned quarries, sand and gravel pits, underground mines, or other mining operations.

Aug 1, 1999

By Rafael Bartra

"El presente texto señala los aspectos geológicos en la mina Yanacocha. La Minera Yanacocha es un Joint Venture, que incluye a Newmont Mining Company (51%), la Compañía de Minas Buenaventura S.A. (44%), yla International Finance Corporation (5%). Dicho distrito tiene una larga historia en prospección y actividad minera, que data desde tiempos pre-Incas hasta nuestros días y es un sistema sulfato dentro de un complejo volcánico de edad terciaria. Asimismo el distrito ha sufrido glaciación postmineral y el yacimiento de La Quinua recientemente descubierto, se encuentra en gravas auríferas derivadas de la glaciación del yacimiento de Yanacocha Sur. De forma que Yanacocha es uno de los principales distritos ácido-sulfato del mundo en términos de contenido de onzas de oro, producción anual y costo de producción. "

Apr 26, 1999