Search Documents

By Hugh Douglas

In the past two years recent increases in silver prices over levels that prevailed for many years have changed supply/demand patterns. On the supply side, a silver mining boom is in progress in the United States and elsewhere. On the demand side, traditional uses of silver by individuals are dropping while industry is conserving. These changes will alter the supply/demand balance and bring about more moderate rises in silver prices, which in turn will impact the mining industry.

Jan 1, 1981

By Carl Hendricks, Malcolm Scoble

There currently exists no viable means of obtaining continuous feedback on blast efficiency. This paper describes the adaptation of a loading shovel to serve as a diagnostic tool to evaluate the success of ground preparation. Work undertaken in a large western Canadian open pit involved microprocessor-based instrumentation for the performance monitoring of an electric mining shovel. The monitored shovel responses proved to be reliable indicators of variations in muckpile diggability. This approach is considered to provide a very comprehensive survey of post blast conditions since such a shovel interacts which every cubic yard of a blast.

Jan 1, 1990

By M. Rantapaa

Measurable improvements in throughput have been documented at Barrick Goldstrike due to increased ore fragmentation through efficient drilling and blasting techniques. A decrease in throughput at the autoclave, due to increasingly hard ore, was identified in early 2002. A team of individuals from the open pit and process areas worked closely on the Drill-to-Mill (D2M) Continuous Improvement initiative to ensure that it would address the needs of both groups, with the target of actually improving throughput in future years, despite the projected harder ores. A series of tests were conducted to determine if adjustments to drilling and blasting could positively influence throughput. Better fragmentation and a subsequent increase in mill throughput were achieved through the use of electronic caps for more precision and flexibility, as well as for allowing extremely fast shots; explosives with a higher velocity of detonation (VOD) to provide for improved shock energy; and improved distribution of the explosives by decreasing pattern spacing. Early tests indicated a significant increase in throughput when processing identified harder ore. It is anticipated that the total process throughput (hard and soft ore) will increase by 6 tph in 2003 due to the improved fragmentation of the hard ore. Barrick Goldstrike?s D2M initiative includes roaster hard ore (BWI>17), as well as autoclave hard ore (BWI>15). Approximately 6 million tons of D2M material were shot in 2003, a relatively small amount compared to the 150 million tons to be mined. The benefit of additional ounces produced should far outweigh the additional drilling and blasting costs.

Jan 1, 2005

By R. Mckinstry, M. Rantapaa, T. Bolles

"Measurable improvements in throughput have been documented at Barrick Goldstrike due to increased ore fragmentation through efficient drilling and blasting techniques. A decrease in throughput at the autoclave, due to increasingly hard ore, was identified in early 2002. A team of individuals from the open pit and process areas worked closely on the Drill-to-Mill (D2M) Continuous Improvement initiative to ensure that it would address the needs of both groups, with the target of actually improving throughput in future years, despite the projected harder ores. A series of tests were conducted to determine if adjustments to drilling and blasting could positively influence throughput.Better fragmentation and a subsequent increase in mill throughput were achieved through the use of electronic caps for more precision and flexibility, as well as for allowing extremely fast shots; explosives with a higher velocity of detonation (VOD) to provide for improved shock energy; and improved distribution of the explosives by decreasing pattern spacing. Early tests indicated a significant increase in throughput when processing identified harder ore. It is anticipated that the total process throughput (hard and soft ore) will increase by 6 tph in 2003 due to the improved fragmentation of the hard ore.Barrick Goldstrike’s D2M initiative includes roaster hard ore (BWI>17), as well as autoclave hard ore (BWI>15). Approximately 6 million tons of D2M material were shot in 2003, a relatively small amount compared to the 150 million tons to be mined. The benefit of additional ounces produced should far outweigh the additional drilling and blasting costs."

Jan 1, 2005

Following a disaster in a mine, it is important to understand the state of the mine damage immediately with limited information. Computational fluid dynamics can be used to simulate and ascertain information about the state of ventilation controls inside a mine. This paper describes a simulation of tracer gas distribution in an experimental mine with the ventilation controls in various states. Tracer gas measurements were taken in the lab experimental apparatus, and used to validate the numerical model. The distribution of the tracer gas, together with the ventilation status, was analyzed to understand how the damage to the ventilation system related to the distribution of tracer gases. This study will be used in future research in real mine measurements to compare collected and simulated profiles and determine whether damage to the ventilation system has been incurred during an emergency situation, the nature of the damage and the general location of the damage.

Jan 1, 2011

By L. W. Hamel

"Two 35 foot diameter enviro clear thickeners were tested in series as CCD units from June until October, 1978. Up to shutdown in July, we ran with automatic bed level control via the level probes and underflow pinch valves. Despite extensive efforts, we were unable to eliminate the surges created between the units by the opening and closing of the pinch valves. Early in July, the best rake speed and gap setting were determined. After shutdown, the enviro clears were run by manually controlling the pinch valves. These efforts were successful.A few mechanical problems were encountered while operating the thickeners. New units should incorporate more support for the drive coupling and a rubber feed seal. A few modifications of the instrumentation control scheme will be required before the units can be fully automated. A less sophisticated automatic flocculant addition system will accomplish the desired results. Control of the underflow withdrawal via the pinch valve should be investigated further. Our best results were obtained by keeping the feed volume to the No. 1 enviro clear constant. Surges were controlled by opening or closing both underflow valves proportionately.Capacity of the enviro clears is dependent of many variables. The ore treated during the test program was much finer than that reported on in R & D Project Report 76-02. Conditions were never steady enough to determine best flocculant dosage or addition point(s). The lowest soluble losses were obtained at very high wash rates. The underflow densities drop but the soluble losses also drop. Regression equations were developed in order to assess the effect of the various parameters. Within the range studied, these equations will predict the performance of enviro clear thickeners as CCD units on Elliot Lake ores. Our results show that the enviro clear thickeners are a viable alternative to the conventional CCD thickener."

Jan 1, 1979

By C. D. Haynes, S. C. Gambrell

The practice of roof bolting in WORLD-WIDE mining activities is very well-known, having been used extensively for over 50 years. The theory of roof bolting, however, is extremely complicated, and only recently have investigators attempted to explain the theory. Various means of stress analysis have been utilized in rock mechanics, most of which reduce rock to an isotropic, homogeneous medium that can be easily analyzed. One of the indirect research methods is the photo-elastic technique, the theory of which is widely known and needs no elaboration. This technique has been used extensively to examine the state of stress around underground openings of various shapes in certain types of strata, and under various loading configurations.'-" In-Situ Mine Roof Trusses The photoelastic technique was employed here to evaluate the state of stress above a mine opening where support is provided by the in-situ mine roof truss. This support configuration, shown in Fig. 1, has gained popularity in recent years, particularly in mines with bad roof conditions." To the authors' knowledge, no scientific determination has been made of the advantages roof trusses may offer over conventional bolting configurations comparable to roof trusses. Ordinary mine roofs usually sag or bulge downward soon after mining. Normally, after some movement the roof begins to stabilize, but the face of this bulging mine rock is usually in tension and will almost always fail unless supported. Because rock fails easily in tension, it is desirable to "preload" the roof, that is, to impress a compressive force on the mine roof to prevent bulging and subsequent tensile failure. Ordinary rock bolting installations, particularly if the bolting is perpendicular to the mine roof plane, do not produce a preloading effect. Although bolting installations squeeze the strata together and produce a beam effect desirable for support, they do not have the advantage of actual uplift. They pull down at the anchorage point with a force equal to the bolt tension which sometimes causes a separation in the plane of the anchorage detrimental to roof strength. In-situ mine roof trusses require the installation of steel tension rods in the roof of the mine much the same as conventional roof bolts, except that the rods are arranged to produce a stress pattern above the upper surface of the opening similar to that of a prestressed beam. The roof rock acts to transmit the compression force. The simplest form of truss consists of two steel rods anchored to the back of holes drilled at an angle of approximately 45 over the mine pillars. These rods are collared near the middle of the room, and the lower ends of the rods are connected by tie rods and turn-buckles. Used in this manner, a small-diameter steel rod can provide essentially the same support as a wide-flange steel beam. By tightening the turnbuckles, an uplift on the roof can be produced. Objective of the Investigation The objective of this investigation was to determine qualitatively the state of stress that exists above a mine roof after the installation of the in-situ mine roof truss vs. that of two angle roof bolts, hereafter referred to as "roof bolts," drilled and placed in the same configuration, that is, 45" above each pillar and connected together in the middle of the room by a bearing member such as a steel beam. Each state of stress was to be identified, insofar as possible, as compression or tension above the mine opening. Model Construction A photoelastic model of a mine opening was coil-structed from -in. thick PLM-4B birefringent plastic and was machined to specification shown in Fig. 2. The dimensions of the opening were chosen to simulate a width-to-depth ratio of 3 to 1. Two % -in. holes were drilled at 45" angles, as shown, to provide for the loading devices. After construction, the model was annealed at 240°F to remove stresses produced during machining.

Jan 1, 1971

By J. van Lookeren

In the case of a reservoir where the oil underlies a large gas cap and overlies bottom water, production can be inzproved considerably if wells are perforated below the water-oil contact rather than opposite the oil-bearing section. The theoretical arguments for this improvement, which in some cases may be tenfold, are supported by experimental evidence. INTRODUCTION Reservoirs frequently consist of one sand body containing an oil layer underlying a thick, gas-bearing section and overlying bottom water (Fig. 1). Wells in such reservoirs are customarily opened up opposite the oil-bearing interval or, rather, opposite the lower part of this interval (Fig. 2). More often than not, it is inefficient or prohibited to blow off large quantities of gas with the oil. This im-psses a severe limitation on the drawdown, which results in low oil-production rates. Because of the small difference in specific gravity between oil and water, the latter will easily cone upwards, so that the production of water together with the oil is not prevented by this completion method. In such a situation wells should be opened deeper, in the originally water-bearing zone. The gas can be shut off by not perforating over the upper part of the interval (Fig. 3) or by a tubing hung close to the bottom of the interval (Fig. 4). Initially much water will be produced, but when steady-state conditions have been established (as depicted in Figs. 3 and 4) larger drawdowns are permissible than in a conventionally completed well, and correspondingly higher oil-production rates will result. Water cuts are only slightly higher because of the small effect of gravity on the water-oil flow distribution. CALCULATIONS The ratio of improvement has been estimated by means of approximate calculations. The completion depicted in Fig. 4 is the most convenient basis for these calculations. By postulating that vertical flow gradients can be disregarded, the Appendix shows that the well-known Dupuit formula can be obtained except for some complication due to the presence of two fluids rather than one. The Appendix makes the reasonable assumption that, for suitable boundary conditions, the oil layer occupies a constant fraction of the total fluid height throughout the reservoir. The oil- and water-production rates can thus be related to the liquid levels in the borehole as follows:

Jan 1, 1966

By K. B. Hodgins, P. Ouellette

"The North American mining industry faces challenging emissions regulations in the coming years with the introduction of new standards for off-road diesel engines. In order to remain competitive, industry stakeholders must invest in new technologies that are economically and environmentally sustainable.Westport Innovations Inc., Vancouver,British Columbia, has developed high-pressure direct injection (HPDI) technology that allows diesel engines to run primarily on natural gas with no intrusive engine modifications while reducing emissions of nitrous oxides (NOx), particulate matter (PM), and CO2 with no loss in performance. This is accomplished through late-cycle, high-pressure direct injection of natural gas into a diesel engine combustion chamber at the end of the compression stroke. A small amount of diesel fuel is injected first to initiate combustion, followed by the natural gas fuel main injection. The diesel cycle and its operating characteristics are fully retained including high combustion efficiency, lowspeed torque, high-power output, no engine knock, and fast response to load changes. Natural gas has not been an attractive fuel alternative in mining operations due to the reduced performance associated with spark ignition engines and the added weight and space required for compressed natural gas tanks. However, liquefied natural gas (LNG) can be stored with less impact on weight and space than compressed natural gas (CNG) by virtue of its increased energy density over CNG.Westport has applied HPDI technology to the Cummins QSK series engines for high horsepower applications such as power generation and mine haul trucking. HPDI can also be applied to other engine manufacturer platforms and market applications. Westport is interested in demonstrating the unique characteristics of HPDI in mine haul trucks to show diesel performance with low emissions levels using low-cost LNG fuel.Retrofitting a Tier 1 engine with HPDI would provide emissions reductions below the EPA 2006 Tier 2 standards while maintaining the performance and efficiency of the Tier 1 platform. The longer-term target is the Blue Sky voluntary standards of 3.8 g/kW-hr (2.8 g/bhphr) of NOx + non-methane hydrocarbons (NMHC), and 0.12 g/kW-hr (0.09 g/bhp-hr) of particulate matter (PM) and future standards. Typically, an HPDI engine is capable of reducing NOx emissions by 40% over diesel operation at the same efficiency. On a mining truck meeting Tier 2 standards, this NOx reduction would translate into NOx emissions approximately 14 t per year lower than under diesel operation. PM emissions are typically reduced by some 60% with HPDI fueling, which would translate into a yearly reduction of 650 kg. Similarly, engine-out greenhouse gas (GHG) emissions are reduced by 21%, resulting in a yearly reduction of approximately 950 t per vehicle.Above those of emissions reduction, efficient natural gas usage in mine haul operations would offer significant benefits in terms of fuel cost savings, which may be further combined with monetary emission credits. HPDI technology would enable operators to exercise environmental stewardship while gaining a competitive advantage in advance of new Tier 2 and Tier 3 emissions regulations. The advantages of natural gas use among mine haul truck operations can be replicated across a broad range of engines and applications."

Jan 1, 2005

By Norman A. Jull

"Factors which affect the separation achieved in a hydrocyclone are discussed and illustrated with graphs of some mathematical relationships.Definitions of separation and sharpness include comment on use of elutriation devices.A plea is made for better evaluation of field data prior to their reporting or use in calculations. Methods of evaluation are suggested, with samples of the relevant calculations.An example of the effect of percent solids errors is given, with computer printout and plotted corrected recoveries.INTRODUCTIONThe range of interest in cyclones runs from a simple demand for classification results to a detailed study of published equations defining cyclone characteristics. Probably this group covers as broad a range and, in an attempt to offer something for everyone, I will begin with general operating comments, then move on to more analytical topics. Ideally, an author would compose his paper after the discussion period, when he would have a better idea of the areas of special interest to his audience.Sor'1e of you may share our incurable fascination with classification, especially as performed in cyclones. It is amazing that such a simple device could be in use for more than 20 years and retain as much mystery as it does. Substantial parts of the mystery have been solved but some remains, to keep up our curiosity. There is at least one valid reason: the unusual compactness of this device, which makes internal observation very difficult. What other unit can you think of which performs such a complex separation between particle sizes, shapes and specific gravities at such high capacity? Retention time in a cyclone is typically 3 seconds!Mutual Agreement - In a cyclone, every parameter of geometry and of operation interacts with every other. In an orderly discussion of individual parameters it would be necessary to repeat, in every section, 11 if all other factors are equal"". Could we agree now, for our mutual convenience, that that phrase is clearly understood between us during the remainder of this paper?"

Jan 1, 1972

Operations and maintenance departments have had a long-standing adversarial relationship. The widespread evolution and adoption of modern management techniques, such as reliability centered maintenance (RCM) and Lean, however, has driven interest in working co-operatively to optimize overall plant performance. Mining and minerals operations have long adopted RCM in maintenance and are now adopting Lean throughout organizations. Such modern management initiatives explicitly call for co-operation between the two disciplines of maintenance and production and many advances have been made in terms of people and methodology. One area that has lagged behind in supporting these developments, however, is information systems. Enterprise asset management (EAM) systems in maintenance and newer manufacturing execution systems (MES) in operations have not been truly integrated in the needed ways. Complicated plants, different software architectures, continually changing conditions and many other variables have led to systems problems, which have contributed to the maintenance/operations divide. Master data synchronization (the plant tree) and integrated reporting of real-time data with transactional data are just two of the issues that are being solved by new approaches in information technology, including web services and service orientated architectures. New technologies are coming on-stream to enable the final bridging of the gap.

Jan 1, 2009

By Gabriel S. Esterhuizen

This paper addresses the need for a method to compare the effectiveness of different support systems when designing ground support in coal mines. At present, support design methods include empirical methods based on observations of past performance of installed support systems, analytical methods where the roof is typically simulated by elastic beams and numerical model analysis. The approach presented in this paper estimates the relative stability of a support design through geotechnical evaluation of the rock mass and numerical model analysis of the interaction between the rock mass and the support system. Models are used first to simulate the design performance at the expected rock conditions. The rock strength is then reduced until collapse is indicated in the model. The stability factor is then calculated as the ratio of the expected rock mass strength to the rock mass strength at the onset of collapse, and is similar to the well-known factor of safety used in engineering practice. The stability factor can be used to assist in developing a final support design by comparing the effectiveness of various support systems and the stability of excavations under various geological and loading conditions. Examples of the method?s application in three different geological settings are presented.

Jan 1, 2012

By M A. Knackstedt

Coupling between deformation processes and rock permeability is a major factor influencing the architecture of fluid migration and the localisation of ore deposition in several types of hydrothermal ore systems in middle to upper crustal regimes. Permeability in many hydrothermal systems is controlled by a dynamic competition between deformation-induced porosity-creation processes and porosity-destruction processes. Localisation of deformation within faults, fractures and shear zones leads to flow localisation, with large-scale flow systems forming when active faults and shear zones link to create percolation networks. Numerical modelling techniques are used to explore the growth of fracture networks and evolution of network connectivity during progressive deformation. Initial results indicate that networks reach a percolation threshold at very low strains. Near the percolation threshold, flow is localised along a small proportion of the total fracture population and favours localised ore deposition. At higher strains, flow is distributed more widely throughout the fracture population and may provide reduced potential for production of high-grade deposits. The distribution of mesothermal gold deposits along a small subset of the total population of co-active faults and shear zones in the Archaean Yilgarn Craton in Western Australia indicates that some hydrothermal systems maintain themselves near the percolation threshold for a substantial part of the lifetime of the system. Fluid-driven growth of fault/fracture/shear networks may lead them to self-organise near the percolation threshold.

Jan 1, 1999

By Luminita Calin

King County (Seattle, WA) is on a monumental task of building the new Brightwater System complete with a new treatment plant, three main conveyance tunnels, a new outfall into Puget Sound and other ancillary works. This paper will describe the first conveyance tunnel, Brightwater East currently under construction by the Joint Venture of Kenny (Sponsor) / Shea / Traylor that is scheduled for completion in early 2010. The project located in Bothell, WA (north of Seattle) is in both King and Snohomish Counties. It was the first of the major tunnel projects that was scheduled by King County for the Brightwater System. The East Contract consists of the following major elements: 14,000 ft of 19'-2' EPBTBM mined tunnel using 16'-8' ID bolted, gasketed precast concrete segments for a primary liner; installing and encasing 14,200 ft each of 48', 66', 27', 84' in diameter steel pipes inside the tunnel along with three runs of fiberoptic cable; 2,430 ft of 72' in diameter microtunnel including three caisson shafts and associated structures; one Intercepting Structure (IS) shell to mine from that is 74 ft deep and 74 ft finished in diameter with 130 ft deep slurry diaphragm walls, tremie slab and final concrete wall lining; one Influent Pump Station shell (IPS) 83 ft deep, twin 77 ft inside diameter cells, with 160 ft deep slurry diaphragm walls, tremie slab, and final lining; two short 12 ft in diameter inter-shaft connector tunnels; one extraction shaft 40 ft deep by 40 ft wide and 140 ft long for connection to the new treatment plant piping.

By G. Karahalios

Industrial minerals have always enjoyed an important share in the technological growth of any country in the world. Today, extraction and trading of industrial minerals has expanded, but is also subject to stricter environmental guidelines. This paper presents the current status as well as the growth potential in the exploitation of industrial minerals in the countries of the south eastern European region, i.e. Albania, Bosnia-Herzegovina, Bulgaria, Croatia, F.Y.R.O.M., Greece, Italy, Serbia and Montenegro, Slovenia and Turkey. More specifically, annual production figures per country are presented for1992-1998. These figures are compared to each other and, where applicable, to world production figures. Trading of industrial minerals from these countries to Europe and the world and its effect to the local economies is also evaluated were such data is available.

Jan 1, 2000

By S Smit, P J. J Strobo

ZINIFEX Century Mine is a zinc, lead and silver concentrate producer. Flotation is the primary method of minerals separation in this circuit. The flotation circuit is quite large with 79 flotation cells. The levels in each of these interconnected cells are controlled at more than 45 level control stations. Due to the multivariable interaction throughout the circuit, good level control was found to be difficult to achieve by just using normal Proportional-Integral-Derivative (PID) control. As a first step in advanced process control, the FloatStar Level Stabiliser, a multivariable controller developed specifically for flotation circuits, has been commissioned at Century mine to solve the level control problems. The first section of this paper therefore discusses and shows the results and improvements obtained by using the FloatStar level stabiliser. The results and benefits of the FloatStar Flow Optimiser are discussed in the second section of this paper.

Jan 1, 2004

By F. Dai

Due to difficulties associated with gripping in direct tension, indirect methods are commonly used to measure rock tensile strength. In this work, we adopt an innovative indirect tensile test method: Semi-Circular Bend (SCB) to measure the tensile/flexural strength of Laurentian granite (LG). The static tests are carried out with a servo-controlled material testing machine and the dynamic tests are conduced with a Split Hopkinson Pressure Bar (SHPB) system. Pulse shaping technique is adopted to achieve dynamic force equilibrium in SHPB to facilitate data regression. Finite element method is used to relate the failure load to the tensile strength. Strong rate dependence of the tensile strength is observed. The flexural strength is higher than the tensile strength measured using Brazilian Disc (BD). This difference is rationalized using the non-local theory. To further validate the method, a coupled Finite element/Discrete element method (Fem/Dem) in conjunction with the smeared crack model is utilized to simulate the fracture process during dynamic SCB tests. The resulting fracture patterns are qualitatively consistent with those from recovered samples. Both the experimental and numerical methods have validated the results and this new method is readily to be used for other rocks and other brittle materials.

May 1, 2009

By G. Kang

The ferroalloys industry has generated historically substantial solid waste. The accumulated waste causes serious problems to the environment. However, it is possible to transform the solid waste into an environment-friendly resource to serve the human being. Consequently, the construction of plants that are ?environment-friendly? and that accommodate ?recycling? has become a target of most ferroalloy producers in the world to ensure sustainable development. This paper introduces the practice of Shanxi Jiaocheng Yiwang Ferroalloys Works, the biggest manganese metal producer in China, in the development of an ?environment-friendly and recycling? process. The process includes power generation using coal gangue, waste from local coal mines; hollow bricks manufacture using slag and fly ash from the power station; cement production using slag from ferroalloy smelting; recovery of ferrous and non-ferrous elements in the dust from the furnace gas cleaning system; application of silica dust in construction and so on. The final objective of the plant is to realize zero discharge of solid waste. The profit of the ?environment-friendly and recycling? process compensates in part for the operational expense of the environment facilities.

Jan 1, 2004

By Douglas Milne

Most empirical and numerical approaches to design in rock mechanics incorporate rock mass classification. Numerical design methods generally use classification values to calculate input parameters for stress-based failure criteria. Empirical methods use classification to allow comparisons between similar rock mass conditions, generally based on a graphical design technique that differentiates stable and failed opening geometries. Classification systems are the best tool available for assessing rock mass properties; however, there are problems with classification systems that should be high-lighted. Rock mass performance can only be realistically estimated by coupling a unique description of the rock mass with known loading conditions. Current classification systems cannot provide a unique classification value. The weightings applied to quantify rock mass properties for classification can result in significantly different rock masses having the same classification values. These weightings have been proven effective for tunnel design and support, but classification systems are now used for many more applications. Rock classification systems evolved from a quick and easy field tool for estimating tunnel stability and support requirements. The need for a rapid field tool means that rock mass classification is relatively insensitive to improved methods of measuring rock mass properties. Problems with classification systems and their application are highlighted in this paper. These problems must be recognized and documented before improvements can be made. An understanding of the evolution of classification systems and their application for both numerical and empirical design approaches is invaluable in highlighting current shortcomings.

Jan 5, 2007

By S. Dicarlo

"In late 1985, B-zone ore was first processed through the Eldor Mines mill at Rabbit Lake. Extensive modifications had been completed in order to mill this ore. In-plant process development was initiated to tune up the new circuits and concentrated on leaching, solvent extraction, impurity and uranium precipitation and tailing and effluent treatment. This process development effort and the results are described.INTRODUCTIONEldor Mines, a division of Eldorado Resources Limited, operates the Rabbit lake mine-mill complex at Collins Bay on the western shore of Wollaston Lake in northeastern Saskatchewan.The first orebody was discovered in 1968 by Gulf Minerals Canada Limited below a small body of water named Rabbit Lake. Ore from the Rabbit Lake (RL) deposit was first processed through the new mill in June, 1975, with depletion scheduled over the next ten years. Continued exploration in the area led to the discovery of four orebodies in the vicinity of Collins Bay: A-zone (1971), B-zone (1977), D-zone (1978) and Eagle Point (1980). Collins Bay is about ten kilometres from the mill facility.In 1982, Gulf Minerals was acquired by Eldorado Nuclear Ltd., who continued the development effort to bring the B-zone deposit into production. The RL pit was mined out in May, 1984 with stockpiled ore providing mill feed until startup on B-zone ore, which was scheduled for November, 1985."

Jan 1, 1988