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By J. Budac, R. Krentz, P. Cordingley, G. Freeman, M. E. Chalkley, H. Scheie

Pressure hydrometallurgical unit operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation for fifty years. This paper traces the history of Sherritt from its origins in northern Manitoba, and the development of the first hydrometallurgical nickel-cobalt refinery in 1954, utilizing pressure hydrometallurgy, to the modern day refinery. Sherritt's involvement with pressure hydrometallurgy during the past 50 years has included the operation of the refinery, the development and licensing of technology, incorporating pressure hydrometallurgical unit operations, to more than 30 companies worldwide, the joint venture at Moa, Cuba involving both leaching and precipitation at elevated temperature and pressure, and the production of specialty metal powders. Developments in each of these areas are reviewed.

Jan 1, 2004

By R. W. Brigstocke

History The birth of the mining industry of Canada took place about 1670. According to Salone (Salone E., La Colonisation de la Nouvelle France, page 205) the first discovery of ore in the country was made by an iron-master, Monsieur de la Potardiere, near Trois Rivieres, Quebec. Under French rule some prospecting was done; but at this time no one seemed to consider the working of mines practicable. It was not until the time that Begon became Intendant, when the Marquis of Vaudreuil was Governor, that mining was attempted. Begon was a patron of industrial arts and did his best to promote home manufactures. The mining industry was developed under his regime and discoveries of copper and lead ores were made in 1730. About this time the St. Maurice Forges were erected to treat bog-iron ore, and they were in operation for many years. Prior to 1747, iron pans to the value of £21,000 were manufactured, together with bar-iron and plough-shares. About 1769, that is, ten years after the conquest by Wolfe, stoves and other articles, and, later, potash kettles, appeared. What is still more interesting to us-or was, at least, to General Wolfe-is that cannon balls made at the St. Maurice Forges delayed his operations. A map dated 1744, a copy of which appears in the report of the Ontario Bureau of Mines for 1913 (Vol. XIX), indicates the extensiveness of the wanderings of the French and also shows the location of the lead mine on the east shore of Lake Timiskaming. Bog-iron ore was turned into metal, with charcoal for fuel, at Norman-dale, Norfolk county, Ontario, in 1813, and at Clementsport, Nova Scotia, in 1825. In a volume published in 1672, reference is made to the occurrence of coal on the Atlantic seaboard, and in 1677 Monsieur Duchesneau, the Intendant, levied a royalty of twenty sous per ton on all coal taken from Cape Breton.

Jan 1, 1932

By R. W. Hodder

"Archean lode gold deposits of both vein and chemical sedimentary types typically have major enrichments of certain rare elements, including Au, Ag, As, Sb, B, W, Se, Te and Bi, coupled with low or negative enrichments of the more abundant and mobile base metals, Cu, Pb and Zn. On the other hand, in massive base metal sulphide deposits Au, Ag, Cu, Zn and in some instances Pb are all enriched by a factor of 200 to 2000 t:'Jf'1pared to background and there is no large separation of gold relative to the base metals.The fluids from which gold was precipitated in veins were at temperatures of 320 to 480°C, at lithostatic pressure, had significant C02, and Na """" K; whereas the fluids which generated base metal deposits were at 250-300°C, at hydrostatic pressure, had C02 < < H20 and Na > > K.Many lode gold deposits are characterized by K, C02 and Si additions to their enveloping rocks, whereas base metal deposits typically have a fixation of Fe, Mg, Si and S in footwall rocks. Lode gold deposits may also have a relatively large halo of low-temperature oxidative, sadie spilitization in enclosing volcanic rocks, where seawater has later streamed into cooling stocks or flows that have initially acted to focus gold mineralizing fluids along thermal contraction fractures. The submarine environment is one hydrologically appropriate for the mixing of two initially independent hydrothermal systems, and the blending of their separate characteristics. Hence, lode gold and base metal massive sulphide deposits appear to be products of two distinctly different crustal and hydrological regimes. The former involves a high-temperature, high-pressure discharge of fluids which probably were generated during dehydration accompanying burial and progressive accumulation of volcanic-sedimentary sequences, with an additional influence of marine water in the near-sea-floor environment. The latter represents thermally driven convection of ocean water at lower temperatures and under hydrostatic conditions.Auriferous fluid systems with only minor base metal content could plausibly be generated during dehydration accompanying burial and metamorphism, when the water-to-rock ratio is low and halogen availability is limited by crustal abundance (- 60 ppm Cl). These two factors may constrain the uptake of the abundant base metals into fluids, but the solubility of rare elements is not constrained by limited fluid; and preferential uptake of Au along with other rare elements may be promoted if such elements compete more successfully for the limited halogens than the base metals, and/or have an alternative complexing agent such as CO or C()j-."

Jan 1, 1982

By R. A. McIvor, R. Levac

"The Stobie No. 7 shaft, 14 ft diameter, double- drum skip hoist, was installed at the INCO Limited Frood Stobie Complex in 1942. Figure 1 shows the hoist layout. The hoist was originally equipped with babbitted journal bearings on the main drum shaft and pinion gears. In 1990, the hoist was modernized with a new braking system, two new 2000 hp D.C. drive motors, a thyristor armature supply and a PLC control system. The new drive motors were connected to the drive pinion gears with a gear type flexible coupling. The pinion gear journal bearings were refitted during the refit in 1990 as the existing babbitted bearings showed signs of wear. The pinion gear journal bearings had always run warm and had external cooling applied during the warm summer months. Figure 2 shows the journal bearings on the pinion shaft. The skip hoist main bull gear and two pinion gears were replaced in 1997 because of cracked bull gear spokes. New drive couplings were installed on the pinion gears and the pinion journal bearings were modified to allow some self-aligning properties to try to reduce the heating and wear on the babbitt. The modifications did not significantly reduce the heating problems and a decision was made in the spring of 1998 to convert the bearings to self-aligning, anti-friction-type bearings.The traditional roller bearings used on double helical pinion drive gears in hoist applications has always been double-row spherical roller bearings due to their high load-carrying capacity and misalignment allowances.Unlike single helical gears, double helical arrangements do not exert axial thrust on the pinion gear bearings, therefore, both bearings in the pillow blocks must float easily with any pinion displacement. Drum misalignment, thrust bearing end play and a multitude of other influences causes continuous axial displacement of the pinions when in operation. This constant displacement or “hunting” of the pinion gear to maintain its centre on bull gear often exceeds the axial clearance limits of spherical roller bearings thus resulting in a continuous sliding motion of the bearing outer rings against the housing seats. With time, the housing fit eventually wears, creating an out-of-round condition for bearing housing (maximum allowable cylindricity tolerance is IT4/2). When this happens, the pillow block housings must be replaced or re-machined to specification. Premature bearing wear and overheating will occur if a housing out-of-round condition is encountered."

Jan 1, 2001

By J. Duncan Keppie

"Auriferous quartz veins occupy zones of dilation. Foldgenerated dilation zones are systematically distributed and are dependent upon the folding mechanism. Comparison of natural and theoretical folds indicates that different mechanisms operated in the Halifax and Goldenville formations.In the slates of the Halifax Formation, the folds are of similar type and internal strain is most intense in the limbs. This internal strain is probably accommodated with little or no dilation.In the meta-sandstone and slates of the Goldenville Formation, a combined flexural and tangential longitudinal strain mechanism, modified by pure strain, produced the folds. Tension fissures produced by this mechanism are: (a) saddle 1'eef veins in slate horizons, (b) veins normal to bedding in meta-sandstone layers in the fold hinges,(c) veins along faults in the cores of tight fold hinges and (d) zones of en- échelon veins in slate honzons in the limbs of folds. Because veins in fold hinges (a, b and c above) account for most of the gold production in the Meguma Group, other factors controlling the distribution and size of these veins are summarized below.1. The size of saddle reef veins is controlled by the curvature of the fold hinge. Thus, a Curvature Index greater than 600 degrees indicates a promising prospect, where"

Jan 1, 1976

By Sandra K. Zacharias

Brass, a deliberate alloy of copper and zinc, has been known since before Roman times. There are two main methods of making brass: (1) Cementation or calamine process - crushed zinc ore (calamine, ZnC03 , or calcined calamine, ZnO), is mixed with charcoal and small pieces of metallic copper and heated to about 900°C in a closed crucible, (2) Alloying - metallic copper and zinc are melted together in a reverberatory furnace. According to most modern authorities (e.g. Smith and Forbes 1955), the calamine process was the only one used in western Europe prior to the 18th century. At that time, the alloying technique began to take over, because metallic zinc was successfully produced on a large scale for the first time. Previously, this had been a problem because zinc vapourizes at 906°C or about the same temperature at which it can be reduced from its ore. Thus, some means had to be devised to collect and condense the zinc vapour (Tylecote 1976). Metallic zinc was known, however, earlier than the 18th century A.O. Several early finds have been made, including a rolled sheet of metallic zinc found in excavations at the Athens Agora dating to the 3rd to 2nd century B. C. (Farnsworth et al. 1949). The Chinese were producing zinc by at least the 10th century A. D. and, by the 17th century, Chinese zinc ingots were being imported into Europe by the Dutch East India Company (Needham 1974). Metallic zinc is also mentioned in several European documentary sources from the 16th century (e.g. Paracelsus, Agricola). This study traces the changes in Western brass making methods from Classical to Renaissance times by examining documentary and archaeological evidence.

Jan 1, 1999

By Brent C. Jellicoe, Phil Robertshaw, J. Murphy, Peter Williamson

Kimberlites and associated diamonds have been the focus of extensive exploration in central Saskatchewan since 1988. During 1989, Uranerz Exploration and Mining Limited identified 71 shallow magnetic anomalies in the Fort a la Corne area from detailed aeromagnetic surveys. By the end of 1991, 18 of these targets had been proven, by drilling, to be kimberlite bodies encased within Cretaceous sedimentary strata. From 1991 to 1997, the number of drill-confirmed kimberlite bodies increased to 69. Our current view, drawing on an integration of geophysical and geological information, is that the kimberlites are composed of individual bodies and multi-vent clusters of coalesced bodies, all apparently constructed of stacked, temporally distinct layers of pyroclastic crater-facies kimberlite. Diamond recoveries and geochemical results from associated heavy minerals at Fort a la Corne remain highly variable, although continued minibulk sampling is expected to improve the estimation of diamond grades for the most prospective bodies.

Jan 1, 2001

By Paul Billingsley

NICKEL Plate mountain coincides closely with that portion of the Hedley mining district which is of economic interest. From it has come almost the entire past production, and the active mines of the present epoch, Nickel Plate-Sunnyside and Hedley Mascot, lie in a compact group near its summit. The Hedley district, which is 210 miles due east of Vancouver, is situated in the Okanagan range of southern British Columbia, where this rather gentle uplift is deeply dissected by the canyons of the Similkameen and its tributaries. The region is essentially part of the Interior Plateau of the Province (Figure 1), but is adjacent to easterly elements of the Coast Range. The Similkameen canyon, 4,000 feet in depth and frequently less than 4 miles from rim to rim, traverses the district from northwest to southeast. The deepest and narrowest portion of the canyon lies between Hedley and Keremeos, 18 miles to the southeast. At Hedley, an important tributary, Twenty Mile creek, enters from the north in a bold canyon, making a focus of unusually rugged topography. Nickel Plate mountain occupies the sector to the east of this junction (see Figure 2) and its flanks are ringed by the cliffs of Twenty Mile canyon on the west and by those of the Similkameen canyon on the south. On the east, it slopes gently to the hanging valley of Eighteen Mile creek, and on the north, with only slight loss of elevation, it merges into the moderately hilly surface of the plateau.

Jan 1, 1941

By Joey Hoang, Robert Johansson, Tapani Keronen, Mikael Jåfs, Jani Jansson, Mikko Korpi

At the Copper 2016 conference in Kobe, Japan, Outotec introduced a vision for the year 2020, wherein smelting would make use of four digital cornerstones: intelligent instruments, advanced process control, improved information management and transparency of and access to data. Since then, this vision coined the phrase “Fully Automated Smelter” with the mission promising a concept where no manual actions from human operators would be needed during normal smelter operations. Replacing repetitive physical work, collection and analysis of everyday production data has a great potential for further automation and will provide productive ways to improve efficiency and safety of smelters in the future. Therefore, a lot of emphasis has been put into developing solutions to automate these tasks and to move people out of harm’s way. A lot of new equipment, systems and optimization tools are under development. In addition, a lot of effort is going into developing dynamic process models and advanced control systems to interface with the plant automation systems. The goal is to integrate all these concepts to meet Outotec’s Fully Automated Smelter vision. This paper will cover these latest achievements toward this vision and introduce the near-future of digital smelting. INTRODUCTION As is well known already, the humankind is currently experiencing a change, extent of which is broadly studied by the governmental, educational and industrial institutions and parties. The wellbeing and quality of life have traditionally been improved alongside the developments in industrial production, which is now about to enter its fourth revolution. Therefore, the current change is often described as fourth industrial revolution, or industry 4.0 (or industrie 4.0, as named by Acatech, 2013) and can be considered anything from small incremental development to a ground-breaking global reset that will affect everyone’s lives. Many seem to agree, that the scale of change will indeed be big, even significantly bigger than the three industrial revolutions before it (Pellini, Weyrauch, Malho & Carden, 2019; Geissbauer, Vedso & Schrauf, 2016; Jansson, Bjorklund, Lahtinen, Heinonen, Jafs & Fagerlund, 2016).

Jan 1, 2019

By Theodore H. Boggs

The battle of the gold standard is not limited to one country alone, or even to a single group of countries. It is being waged merrily in many important commercial and industrial quarters. Though it is not always a practical issue calling for immediate attention, it is none the less, quite widely, engaging the thought of bankers and other students of finance. The controversy arises, in the last analysis, because of the desire of men to secure a stable currency. There are two ways of restoring a reasonably stable currency system: (1) the re-establishment of the gold standard, or (2) the deliberate and artificial management of a paper currency. Both systems are well known. The gold standard was in use prior to the war in the principal commercial countries. A currency of inconvertible paper has been at times employed in the past in various countries; for example in Britain from 1797 to 1821, and in the United States from 1862 to 1879. The gold standard, as all are aware, implies the selection of gold as the standard of value. The unit of value is a fixed weight of gold and, so long as the standard remains unimpaired, all other means of payment are maintained at a parity with standard gold coins. And gold coins alone constitute the standard money, inasmuch as their value as bullion equals their value as coins. Under the gold standard this would not be true of any other form of money, although all other varieties of money, including bank notes, government notes and silver coins would be freely convertible into gold money. Strictly speaking, the gold standard also implies that the gold money in turn shall itself be freely convertible, through melting, into gold bullion and freely exportable.

Jan 1, 1925

By Yun-Jie Wei

Seismic areas were in the eastern margin of the Qinghai-Tibet plain, whose structures were complicated, mainly composed of Maowen fault, Yingxiu fault and Pengxian-guanxian fault. The rapid rise of the Qinghai-Tibet plain led the crustal material of the eastern edge to move to the southeast along the faults on a large scale since the late Cenozoic; Minshan block structure and Long Men Mountain tectonic zone represented the strong nappe thrust movement as the east boundary of Chuanqing slip block; the stress was accumulating when squeezed, which to a certain extent resulted in breakdown of the crust, and earthquakes. The shock speed, high-energy accumulation, and the reversed dextrorotation of the earthquake fault characteristics et al. happened, which caused the development of secondary geological disastersts. According to on-site investigation, the typical geological disasters had thrust rock collapse, the instability deposit, the revival of potential debris flow et al. whose genetic model had been analysed.

May 1, 2009

By Tad Crowie, Victor Delgado, Nick Katsikaros, Tim Hughes

"A number of silver producers have identified a need for a system to recover silver and gold from base metal flotation concentrates on site rather than sending the concentrate to third party smelters to improve mine economics. Historically intensive cyanidation has only been used for coarse gold gravity concentrates in batch machines but Gekko have applied the InLine Leach Reactor (ILR) to these difficult to leach concentrates.The ILR’s unique ability to operate at various solid to solution ratios, high mass capacity, the ability to handle fines, the use of peroxide to aid silver leach kinetics and simple operation has resulted in significant economic benefits to Hochschild PLC’s Selene and Arcata operations. This paper describes the commissioning phase of the ILR5000BA intensive cyanidation reactors on concentrates from the Selene mine at the Ares Concentrator.INTRODUCTIONIntensive leaching of high grade concentrates in gold ore treatment is now commonplace and is considered an essential feature of most gold circuits (Lane, Fountain and LeBrooy, 2008). The devices commonly used for intensive leaching (InLine Leach Reactor, Acacia Reactor, etc) are specifically designed for the typical coarse nature of the concentrate.In some of these intensive leach applications, significant amounts of silver are co-recovered with the gold. In fact, the intensive leaching conditions of 1 to 2% NaCN in solution and high dissolved oxygen levels, overcome the issue with silver’s slow dissolution rate in traditional CIL/CIP circuits and avoids the formation of insoluble silver sulphide minerals on the surface of the gold (Marsden, 2006).There are a significant number of mine operators producing silver in the form of mixed base metal sulphides flotation concentrates. Typically the mine operators are paid for the silver after processing of the concentrate by the base metal smelter whom recovers the silver during the refining process."

Jan 1, 2010

By G. Van Weert

In the spring of 2010 double refractory ores from historical stockpiles were processed through Barrick&apos;s Goldstrike pressure oxidation facility, thereby providing preg robbing feeds for a variety of metallurgical testwork. This paper describes the effects of amount, type, place and time of addition of activated carbons on CIL gold recovery and shows that native carbon in plant PDX&apos;ed discharge solids can still preg rob gold loaded activated carbon.

Jan 1, 2011

By G. M. Carr-Harris

"THE SUBJECT of permanent molding has received a great deal of attention in the technical press as illustrated by the many excellent articles in the bibliography which follows. In general, this covers the period 1940-1958 and is merely representative of what is available. Numbers in •brackets refer to items in the bibliography.It may be desirable at the outset to give a few definitions covering those terms directly related to this subject. The following is a definition of permanent-mold casting as given by J. W. Meier in a paper, ""The Non-Ferrous Metals and Alloys"", read before the Ottawa Valley Chapt.er of the American Society for Metals:""Permanent Mold Casting is used where a large number of castings of the same part are required and higher mechanical properties, greater density and closer tolerances are essential. Since metallic mold s are very expensive, the number of castings must be sufficient to, defray, at least partially, the added expense. Molds are usually made from a good quality cast iron, 1but other mold materials, such as the aluminum and copper alloys, graphite, ceramics, etc., are being used in certain cases. Important factors in permanent mold casting are the mold temperature; the proper mold dressing; and, as in all other casting methods, the mold geometry, that is to say, the design of spruces, gates, risers and vents""."

Jan 1, 1960

By J. A. Scott, K. Moreau, H. Shang

"Trials of automated technology at underground mine sites around the world have reported increased production and the potential for lower energy consumption. Autonomous mining eliminates a range of delays related to operator downtime and travel to the workface and facilitates continuous operation in conditions that are unsafe for workers. Automation also introduces complexities and safety hazards arising from equipment–personnel interactions; automated processes must be isolated from other stope-cycle–related activities such as production drilling, development, loading, and backfilling, poten¬tially requiring changes to the mine design to maintain an efficient and safe operation. This paper reviews and discusses the implementation of automated equipment in deep underground mining operations and the challenges and advantages associated with the technology. ¦ KEYWORDS Automated equipment, Emissions reduction, Energy, Productivity, Sustainability, Technology, Underground mines RÉSUMÉ Des essais de technologies automatisées dans des sites miniers souterrains aux quatre coins du monde ont indiqué une production accrue et la possibilité de réduire la consommation d’énergie. L’exploitation minière autonome élimine tout un éventail de retards liés aux temps d’immobilisation des opérateurs et aux déplacements vers le front de taille, et facilite l’exploitation continue dans des conditions qui s’avèrent peu sécurisées pour les travailleurs. L’automatisation introduit également des complexités et des risques pour la sécurité, qui surviennent en raison des interactions entre l’équipement et le personnel. On recommande d’isoler les procédés automatisés des autres activités liées au cycle des chantiers telles que le forage de production, le développement, le chargement et le remblai, ce qui pourrait entraîner des changements au niveau de la conception de la mine afin de préserver rendement et sécurité dans l’exploitation. Cet article examine et aborde la mise en oeuvre de l’équipement automatisé dans des exploitations minières souterraines profondes, ainsi que les enjeux et les avantages associés à cette technologie. ¦ MOTS CLÉS durabilité, énergie, équipement automatisé, mines souterraines, productivité, réduction des émissions, technologieINTRODUCTION As the mining industry continues to exhaust easily accessible orebodies, the need for efficient, deep (typically below 2,500 m) mine operations increases (Atlas Copco, 2013a); however, the mining process can become economically infeasible at great depths because operation costs drastically increase. This has resulted in investigations into automating mining operations as the industry strives for improved productivity (Schunnesson, Gustafson, & Kumar, 2009) and ways to remove personnel from hazardous work areas."

Jan 1, 2019

By H. Ito, T. Takasu

Effects of a mechnochemical treatment to oxide Ni ores have been investigated to enhance the extractive ratio of Ni from them in acid leaching process. High intensity grinding by a planetary boll mill showed strong effect to enhance the extractive ratio of Ni, for example , 10% of extractive ratio of Ni in sulfuric acid leaching(0.05mo1/1,at room temperature) increased to more than 90% with 60min. of planetary boll milling. Effects of additives(sulfur and some oxidants) on the mechnochemical treatment have also studied. Sulfur showed almost no effect to enhance the total Ni extractive ratio but increases the selectivity of Ni extraction. More than a half of Ni could be extracted by water when Ni ore was grinded at addition of Na2S207 in the milling treatment. Some effects of mechnocemical treatments to Ni ore are summarized in this paper.

Jan 1, 2005

By Judy K. Todd

Double benching has been utilized as an excavation technique in open pit mines for many years. This process involves drilling, blasting, and excavating the material for the design bench height. A second bench is then excavated without the creation of a catch bench, i.e. only minimal offset from the first bench face is allowed when drilling off the second bench. The result is a double high bench face or double bench. When drilling off the second bench, the offset of the drill from the bench face projects the lower bench face into the pit up to an extra five meters. This reduces the maximum attainable bench angle, enhances the probability of rock escaping the catch bench and increases the overall strip ratio. The generally utilized process of trim blasting also can impact on the final bench profile by contributing to blast damage of the face. BHP Billiton Diamonds Inc., Ekati Mine Diamond MineTM, has pioneered the usage of a technique that eliminates this offset. Double benching is accomplished by drilling a single, 30m pre-shear (two 15m benches) to define and protect the final bench profile. This article provides a comparison of the attained face angles obtained in the field utilizing both of the above methods, as well as a comparison with the analytically predicted angles prior to excavation.

May 1, 2002

By R. J. Goodman, P. Lafleur

This paper presents a current interpretation and projections of recent statistics on raw materials availability based on familiarity with the Canadian steel industry and its development. Problems and opportunities are recognized and discussed.

Jan 1, 1976

By Phillip I. Merritt

"IntroductionDuring and since• the war, it has been my privilege to work closely with those in Canada who are responsible for the vital raw materials needed in our co-operative atomic energy programme. The understanding which has developed between our two groups in this all-important enterprise has been a great source of pleasure. We in the United States are aware of the importance of the contribution made by Canada to this project, and we look forward to continuing our mutually advantageous relationship.The impact of World War II, and the decision by Canada, Great Britain, and the United States to join in a programme for the development of atomic weapons, created a sudden and immense demand for uranium minerals. Early in the raw materials programme, it was evident that sufficient raw materials to fulfill war-time atomic weapon requirements could be secured from three sources: the rich pitchblende deposits of the Eldorado , mine at Great Bear lake; the Shinkolobwe mine in the Belgian Congo; and as a by-product of the vanadium industry of the Colorado Plateau in the United States. In the early part of the programme, therefore, our joint efforts were directed toward obtaining immediate maximum production from these localities. The contribution made by Eldorado Mining and Refining (1944), Limited, both in supplying and refining raw materials, was and continues to be of vital importance.In addition, it was also obvious from the first that in this programme, as in any mining enterprise, exploration activities directed•toward the discovery and development of new sources of uranium ore were essential if production were to be maintained over an extended period of time. In order to satisfy obvious security requirements during the war, it was necessary to proceed with this exploration programme, both in Canada and the United States, as secretly as possible. With the end of the war, and the revelation that an atomic weapon had been developed, however, secrecy in exploration was no longer required. The important thing was to get on with a broadened exploration programme."

Jan 1, 1950

By Steve Hubbard, Brad Marchant, Rolando Cuadra

"Triton Mining Corporation acquired the rights to Mina El Limon in Nicaragua in 1993 by international bid. The bid included the gold operations at Limon and an exploration concession of approximately 4000 km2. Triton assumed control of operations and exploration in May 1994.The Limon mine is located in west-central Nicaragua, approximately 100 kilometers northwest of Managua. The climate is tropical, characterized by a wet season from May through October, and a dry season November through April. Gold at Limon is associated with both banded quartz and silicified breccia veins in Tertiary volcanic rocks, belonging to the lower Coyol Group. Mining is from two open pits and one mechanized underground operation. A second underground mine is currently under development for production during 1997.This paper describes the expansion of the milling facility at El Limon from a nominal capacity of 400 tonnes/day, producing approximately 20,000 ounces of gold annually, to the existing 900 tonne per day mill operation. Engineering of the new mill facility was initiated in September 1994 and construction was completed a year later."

Jan 1, 1997