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By Ros Taplin

Realizing the potential of cutting greenhouse gases (GHGs) associated with mining, a variety of approaches has been proposed for their mitigation. The Clean Development Mechanism (CDM) under the Kyoto Protocol to the UN Framework Convention on Climate Change (UNFCCC) has been a key mechanism to assist in implementation of mitigation measures. The objectives of CDM are not only to assist Annex I countries in meeting their GHG emissions reduction targets with cost-effective reduction but also to achieve sustainable development in non-Annex I countries. However, apart from China, India, Brazil and Mexico, many developing countries are still in the stages of formulation or realizing CDM strategies. Projects associated with methane capture and flaring are the fourth most prevalent type of CDM project internationally. This research primarily has addressed emissions abatement and sustainable development aims and effectiveness of registered CDM projects associated with coal mining in China. The paper reviews 30 currently registered CDM projects in China on the UNFCCC database and six other non- Chinese projects. Systematic evaluation involving content analysis of documentary evidence regarding coal mining CDM projects is presented in relation to firstly, quantitative reduction of GHG emissions and secondly, sustainable development outcomes. The projects have been assessed via a set sustainability criteria. Overall it was found that sustainable development goals are only briefly referred to in Project Design Documents, Letter of Approvals and validation documents. Varying types of sustainability initiatives have been implemented with weak to strong indications of effectiveness. This has implications for the future effectiveness of CDM projects in the mining sector, the proposed new market mechanism under UNFCCC, and for assessment of projects under mechanisms established outside the UNFCCC.

Aug 1, 2013

By Michael S. Moats, Addin Pranowo, Gerardo R. F. Alvear F., Nigel Aslin

The toxicity of arsenic is well known and documented. However, the presence of arsenic in copper electrorefining anodes and electrolyte is critically necessary to produce high quality cathode. Arsenic as well as antimony and bismuth concentrations vary depending on their relative concentration in the anode copper received from the smelter. This paper will discuss the behaviour and benefits of arsenic in copper electrorefining and the detrimental effects of antimony and bismuth on cathode quality and tankhouse performance. This will include the minimization and mitigation of problems associated with arsenic, antimony and bismuth including cathode contamination, floating slimes, scaling and anode passivation.

Jan 1, 2014

By J. P. Rajot, H. Mouzannar, M. Bost

"The design of rock foundations may need to evaluate shear strength of rock-concrete interface by performing laboratory direct shear tests. A series of tests were carried out on specimens for different values of the spacing free of encapsulating material about the shear plane and different values of normal stress. Different kinds of failure were observed and not necessarily at the rock-concrete interface. The spacing free of encapsulating material appeared to be of significant influence on the test results. A mechanical analysis is presented which illustrate the influence of the loading conditions in the direct shear box on the failure mechanism. INTRODUCTIONThe design of rock foundations subjected to significant lateral loads requires defining the value of the shear strength of the interface between rock and cast in place concrete. Verifying the stability against sliding of strip footings subjected to inclined loads (SETRA, 2009) or concrete gravity dams (CFBR, 2013) are common examples where design modelling approaches imply the shear strength, sometimes the deformation behavior, of the rock-concrete interface, more or less assumed as a failure plane.Defining the behavior of rock-concrete interfaces relates to tribology. Many studies have been conducted to improve the representation of this behavior (e.g., Johnston & Lam, 1989; Kodikara & Johnston, 1994; Gu, Seidel & Haberfield, 2003; Saiang, Malmgren & Nordlund , 2005; Fishman, 2008; Eltervaag, 2013; Gutierrez, 2013), raising many questions. The behavior appeared to be influenced by many factors such as the geometry of the interface which is not planar, the roughness of the natural rock, the rock mineralogy and the concrete formulation. In addition, the study of the shear strength of rock-concrete interfaces involves considering the two different deformation behaviors of both rock and concrete. Finally, the observed failure mechanism is strongly influenced by the initial cohesion due to adhesion between the two materials when concrete is directly cast onto rock."

Jan 1, 2015

By Neal Harries

Ground movement is normal in open cut mining operations, mainly caused by excavation response and blasting. Movement of the ground can be acceptable provided it is not unexpected and catastrophic. However, in steep mine walls and the very large open pits being developed today the consequence of slope collapse can be catastrophic. Such risks can be minimized at the planning stage by reducing slope angles, but this carries a very high cost. Also, instabilities which develop whilst mining can lead to ore reserves being quarantined, which represent a high cost to the mining operation. In spite of such safety measures, unexpected failures have occurred in the past. These issues motivated the development and production of the slope stability radar (SSR). There are currently over 80 GroundProbe SSR systems deployed in metalliferous and coal mines in 17 countries. The unexpected failure of rock walls at mining sites is a major cause of death and serious injury. Slope failure is also one of the major causes of economic and production losses. An unexpected wall failure can bury critical equipment. It also disrupts the mine plan. It is common to cease mining for several days or weeks following a wall collapse due to uncertainty over stability. Direct economic losses in remediation alone can easily exceed $1,000,000 per incident. The economic costs of injury or fatality are much higher including closure of mines during the incident investigation process. Massive wall failure can result in direct and indirect costs measured in millions of dollars. This paper will present some recent case studies of the SSR operation in open cut mines in North America, including Thompson Creek Mining Company (Idaho), Smoky Canyon Mine (Idaho), and a general case study on extreme cold weather use of the SSR.

May 1, 2009

By Q. Han, W. Dai

Al-Ti-B type master alloys have been widely used in the grain refinement of aluminum since 1940s. The introduction of Al3Ti and TiB2(AlB2) particles reduces the grain sizes down to about 200 micrometer level and makes cold work possible. However, the mechanism for the grain refinement is still not clear, though it is believed that TiB2 in the presence of Al3Ti nucleate a-Al grains in solidification. This paper presents our finding on the formation of (Ti,Al)B2 solid solution, which leads to a proposed theory on grain refinement by Al-Ti-B type master alloys that upon addition into aluminum melt stable TiB2 particles react with aluminum slowly and release titanium into the melt. The titanium thus released in combination with titanium in the melt through dissolution of Al3Ti maintains a transient titanium-rich layer on the surface of (Ti,Al)B2. This layer offers a low crystal mismatch with a- Al and promotes the nucleation of aluminum grains.

Jan 1, 2014

By K. Tsuchihashi, A. Kishimoto, T. Uda, Y. Kado, S. Maruyama

We recently proposed a continuous production process for titanium metal with some experimental results. In the process, titanium tetrachloride is reduced by Mg in the presences of Bi to form a Bi-Ti alloy at 900ºC. At this temperature, the obtained alloy is liquid and allows for the continuous removal of product and heat from the reaction vessel. The obtained Bi-Ti alloy was vacuum-distilled at 1000ºC for 24 hr, and 98 at % (92 wt %) titanium, which was easily crashed to powder, was obtained. Bi solvent was selected because of the highest titanium solubility at 900ºC and the moderate vapor pressure among the candidate metals (Bi, Sn, Pb, Zn, and Sb).

Jan 1, 2014

By T. P. Riordon

"Major swings in the silver price since 1979, along with the ever constant fight to maintain ore reserves has forced United Keno Hill Mines Limited through several unique series of events in order to survive in the 80s.This paper is specifically meant to be a description of safety and productivity improvements achieved to ensure the survival of a silver mining community ill the Yukon. There are, however, other events and conditions that must be described to complete the story and this paper attempts to do that as well IntroductionUnited Keno Hill Mines Limited, a subsidiary of Falconbridge Limited, is the only silver producer in the Yukon. Operations are located in north central Yukon, in and around the small town of Elsa, latitude 62.5 °, about 275 road miles from Whitehorse. The Arctic Circle is about 185 miles due north of the town.Temperatures in 1986 ranged from a high of 28.5°C in July to a low of -37.0°C in November, however, much lower temperatures have been recorded in previous years. Due to the mountainous terrain the town of Elsa is completely in the shade from mid-November until early February, a period of about 12 weeks.The Elsa area, as is most of the north, is considered semiarid with an average precipitation level of about 15 inches. Vegetation, however, is quite abundant though slightly dwarfed at the townsite elevation of 3200 feet above sea level: Many of our operating and exploration portals as well as our open pits are above the tree line. Permafrost in the area has been recorded up to 400 feet below the surface."

Jan 1, 1988

By Lesley Hymers

First Nations Natural Resources Youth Employment Program PDAC Mining Matters ? Charitable organization ? Provide education to students, teachers, and the public about rocks, minerals, metals, and mining ? Provide current information and offer exceptional educational resources that meet provincial Earth science and geography curriculum expectations First Nations Natural Resources Youth Employment Program ? Provide instructional development workshops for educators who are teaching Earth science and geography ? Since 1994, reached more than 400,000 students, teachers, industry representatives, and members of the public

May 1, 2009

By Robert D. Brown

"All ten Canadian provinces have now tabled their 1981 /82 budgets . Only the provinces of Ontario, Quebec and British Columbia made more than minor modifications to their tax structures, with both Ontario and Quebec imposing major tax increases. In the past year, the federal budget was also released in the spring. Not so this year: we have that to look forward to in the fall!This month, Tax Notes presents a brief summary of the more significant tax changes introduced at the provinciallevels in the last months.Summary of provincial tax rate changesThe tax changes in this year's provincial budgets were both up and down- but there were far more tax increases than tax cuts.At the corporate tax level, two provinces, New Brunswick and British Columbia, increased their general corporate income tax rate; the former by two percentage points and the latter by one percentage point. Quebec, rather unexpectedly, sharply cut its corporate tax rate on business income, but increased some of its other business taxes at the same time. British Columbia reduced its corporate tax rate on small business income by two percentage points and Saskatchewan by one percentage point."

Jan 1, 1981

By A. P. E. Dirige

In order to maximize the recovery of ore and to save on costs in undercut mining, backfill of low cement content is used to fill the mined out excavations. This backfill mass is supported by a sillmat structure cast from cemented backfill of very high strength. The stability design of sillmats must be carefully studied to provide very effective, safe and economic mining operations. This paper presents a methodology and procedures for sillmat design based on three engineering modeling approaches: analytical, numerical and centrifuge modeling. Application of the design approach is demonstrated from a design study conducted for an underground gold mine, aimed at minimizing backfill binder content and at producing cost efficient paste fill recipes for sillmat construction. Application of the engineering design recommendations was projected to result in substantial annual cost savings to the mine operation.

May 1, 2007

By John H. Fowler

"Barytes is one of the major components of drilling fluids used in oil and gas well-drilling. This mineral's close association with the petroleum industry bestows it with a commodity status not enjoyed by many other industrial minerals. Approximately 85% of world barytes production is used as a weighting agent in oil and gas well drilling while the remaining 15% is consumed mainly in the manufacture of barium chemicals, glass and as a pigment, filler or extender.Barytes mining began in Nova Scotia around 1865 and has continued until the present. Currently there are three barytes producers in the province one exporting pharmaceutical-grade barium sulphate and the other two supplying drilling mud-grade barytes to the offshore. Several barytes exploration and development programs are underway with excellent possibilities that Nova Scotia deposits will supply a significantly larger share of the drilling mud-grade barytes used in east coast drilling programs.Currently there is renewed interest in barytes activities in Nova Scotia because of its use as a weighting agent in drilling flu ids used in offshore oil and gas drilling programs.This paper reviews the use of barytes by the well drilling industry; outlines the history of barytes mining in the province, progressing to present-day exploration, development and production activities underway in Nova Scotia; and concludes with the market potential for Nova Scotia barytes."

Jan 1, 1986

By Yuki Tsunazawa, Sho Fukui, Chiharu Tokoro

"A milling process is one of the important unit processes in mineral processing. In the milling process, the control of particle size distribution is necessary for the later physical separation process. Since the milling process is strongly affected by the equipment designs, operation conditions and raw materials, the control for particle size distribution of milling products is mainly based on empirical rules. Recently, the discrete element method (DEM) has been widely used as an effective tool to investigate the behavior of grinding media. Although the behavior of grinding media can be accurately simulated, it is not well-established the way to predict particle size distribution after milling by the DEM simulation.The objective of this study was to develop a new method to predict particle size distribution in ball milling using the DEM simulation. To predict particle size reduction, a correlation between experiments and the simulation was investigated in various operation conditions, that is, wide range of the rotation speed and the filling ratio of grinding media. In experiments, after lime stone was ground, the average and variance of particle size distribution were evaluated using some kinds of distribution equations. In the DEM simulation, direct simulation of particle disintegration in milling process is generally very difficult because of huge computational load. Therefore, collision energy between grinding media balls orgrinding media ball and wall was used as a factor of particle disintegration.As a result, a good correlation between experiments and simulation was obtained. In addition, the particle size distribution in ball milling could be predicted using this correlation. Therefore, these results indicated that the use of the correlation between experiments and the DEM simulation was an effective approach of predicting the particle size distribution in milling process."

Jan 1, 2016

By Michel Dagbert

"This paper illustrates the different ways grade-tonnage curves can be generated f or a mineral deposit. It emphasizes systematic discrepancies between reality, estimates and actual production according to different estimation methods and grade control programs. It does not offer a universal solution to the prediction of grade-tonnage curves. Hopefully, it will inspire caution to mineral economists who use estimated grade and tonnage data in the establishment of an optimum cut-off grade for a mining operation.IntroductionThe value of a mineral development venture often depends on a grade-tonnage curve. Statistics can help. The idea is to divide mentally the orebody into small blocks called selective mining units or SMUs. A SMU is an idealized version of the quantity of rock the grade of which will be tested against the cut-off at the time of mining. It could be as small as a truck load or a shovel load in very selective operations like some uranium mines where radiometric probing of each truck or car is performed. More typically, in an open pit operation, it will be the smallest zone flagged as ore from blast hole data, e.g. a 5 m by 5 m by 10m block, if blast holes are on a 5 m grid and bench height is 10m. Having defined the SMUs, the grade-tonnage curve determination amounts to evaluating the grade distribution of all the SMUs that can be mined in the depo sit. If we know this distribution we simply apply the cut-off to it and we get the number of SMUs above the cut-off (i.e. ore tonnage) and their average grade. .Assessment of the grade distribution of SMUs from exploration drill hole data is not an easy exercise and much has been published on the subject (David, 1972; Marechal , 1972; Huijbregts, 1975; Marechal, 1975; Guibal and Touffait, 1982). In this paper, we use a gold mine example to illustrate the influence of SMU size on the results. With the same example we also show that ""common-sense"" methods of grade-tonnage curve determination can sometimes be misleading."

Jan 1, 1987

By P. Venkatasubramanian

"In recent years, computer based ""expert systems"" have been taking on large complex tasks for which no exact algorithmic solutions are feasible; tasks previously reserved for human experts requiring empirical knowledge, judgment, experience, developing a ""best solution "" by the use of plausible reasoning. Mining method selection is an appropriate area for the application of an expert system because extensive and detailed knowledge is required to make a ""best"" interpretaion of frequently ambiguous geological information. The expert system model presented here would enable users to apply expert knowledge to the evaluation of methods for coal deposits mineable by underground methods. IntroductionIn an increasingly complex and specialized world, human expertise spanning scientific, economic, social and political issues plays an increasingly important role in all branches of engineering. This is especially true of mining engineering. The number of scientific and professional disciplines involved in mine planning and evaluation, illustrates the problem. A conservative list includes geology, geophysics, geotechnics, hydrology, mining, environment, and economics.Engineers are almost obliged to be experts in at least one of the above disciplines if they are to handle the volume of information required in the planning process. Although computers have become indispensable tools in many endeavours, there is continued reliance on the human expert's ability to identify and synthesize these diverse factors, to form judgments, evaluate alternatives , and make decisions . This is especially true with regard to problems that are not easily amenable to precise formulations.The precious resource of human expert is also fragile and transient. The departure of a crucial expert from an organization ma y cause serious dislocations. Senior experienced people impart their knowledge of younger colleagues, but the demand for their talent may not leave sufficient time for such educational efforts. In recent years, computer based "" expert systems"" have been taking on large complex tasks for which no exact algorithmic solutions are feasible; tasks previously reserved for human experts, requiring empirical knowledge, judgment , experience, developing a ""best solution"" by the use of plausible reasoning."

Jan 1, 1988

By Pura Alfonso, Sarbast Hamid, Hernan Anticoi, Eduard Guasch, Josep Oliva

"Av. Bases de Manresa 61-63, Manresa (08242) Barcelona, SpainTantalum is a strategic metal and an improvement of the mineral processing is an important issue. The main objective of this work is to optimize the grinding technologies for tantalum ores with high pressure grinding rolls. The selected ore for this study was an altered leucogranite from the Penouta Open Pit Mine (NW Spain). In the present work mono-size experiments have been carried out using grinding rolls with controlled pressure. The particle size distribution has been monitored in the input and output of the high pressure grinding rolls for each experiment. The cylinder pressure that is transmitted to the particles has been determined. New population balance models are presented for high pressure grinding rolls with parameter adjust for tantalum ore. The obtained model uses the physical description of particles under the comminution action of the grinding rolls. The obtained results are in agreement with other models and the errors in the adjustment are low. The selection function proposed for this model describes adequately the breakage probability of the particles inside the high pressure grinding rolls. The presented model can be a good alternative for simulating a high pressure grinding roll process. INTRODUCTIONTechnology for grinding have been improved for many years, introducing new variables and parameters involving energy consumption, mechanical stress analysis of the compression particles or pressure application for optimizing the comminution (Morrell et al, 1997). High pressure grinding rolls is a modern technology that is proven to reduce the operating costs in full scale plants when compared with other milling technologies. Its benefits on energy saving and simplicity in the process have been studied and applied, first in the cement clinker industry (Abouzeid & Fuerstenau, 2009) and after in mining activities, especially in metallic ore deposits (Austin et al, 1991; Guevara & Menacho, 1992; Morrel et al, 1997; Torres & Casali 2009; Numbi & Xia, 2015). Many author structures of the High Pressure Grinding Rolls modelling in three main branches; (a) throughput modelling, (b) Power and energy model and (c) particle size distribution modelling (Austin et al, 1991; Guevara & Menacho, 1992; Austin & Trubelja, 1994; Morrel et al, 1997; Torres & Casali, 2009)."

Jan 1, 2016

By Donald Roberts

"Parameters f or design and development of an emergency hoist system (Fig. I) were submitted to Timberland Equipment Limited of Woodstock, Ontario by the Potash Corporation of Saskatchewan Mining Limited.The unit is the first of its kind in Canada. Not only does it comply with the province of Saskatchewan's mining regulations, but has the added advantage of being completely mobile and self-contained.As well as being useful in the mining industry, the mobile hoist unit could be used in other emergency situations such as rescuing people trapped in wells.JustificationRevisions to the Mines Regulations under Section 13 of the Occupational Health and Safety Act, 1977, of the Province of Saskatchewan stipulate as follows:"" Section 410 .04(4) The Mine Employer shall make adequate provision at every mine where any worker is hoisted in a shaft not equipped with a manway to enable an y such worker trapped in a conveyance in the shaft to be rescued . "" It was not possible to equip the shafts at PCS Mining' s Divisions with "" manways"" and therefore an alternative was required.BackgroundThe Potash Corporation of Saskatchewan Mining Limited, a subsidiary of the Potash Corporation of Saskatchewan, operates four potash mines. Of these, three, Cory, Rocanville and Lanigan Divisions are wholly owned while the fourth, Allan Division, is 40% owned by Kidd Creek Mines Ltd., but managed by PCS Mining. The four underground operations all have a service and production shaft.From 1979 to 1981 the PCS Mining Division, along with Central Canada Potash, were developing an idea to use the existing ground-mounted timberland hoist at Lanigan as an emergency hoist. This hoist was used in the past for rope-up work at both Rocanville and Lanigan and other potash mine s. The Department of Labour at this time had concerns about the time it would take to load, t ran sport and re-install the hoist on a foundation when needed for an emergency. Weight and size made this particular unit very cumbersome for transporting.In addition, the speed at which this hoist operates is too slow for rescue work. When the Department of Labour expressed concern that this unit would be unsuitable for these rea sons, a search for a suitable unit was initiated.The project responsibility for procuring an emergency hoist for the Potash Corporation of Saskatchewan Mining Limited was assigned to the author, a shaft/ hoist specialist a t PCS Mining."

Jan 1, 1986

By Frédéric Flament, Mary Goldman, Gille Barbery

"Pilot plant testwork on autogenous and semi-autogenous grinding was conducted at the Centre des Recherches Minérales du Québec (CRM) to investigate the effect of ball addition, solids concentration in the feed, specific energy consumption and feed size distribution.A mathematical model that incorporates breakage and surface mechanisms of loss of mass was developed to predict load size distribution of autogenous and semi-autogeneous mills. An empirical model was used to predict product size distribution of autogenous and semi-autogeneous mills.IntroductionAutogenous (AG) and semi-autogenous (SAG) grinding circuits offer potential capital and operating cost savings when compared with conventional grinding. Empirical relationships have been developed to calculate specific power consumption for SAG mills using pilot plant test results (Mular et al., 1989; Barrett and Allan, 1986). Empirical models can be obtained from plant practice data but are applicable only to the particular ore and set of operating conditions used in the model. Grinding mechanisms have to be taken into account in order to develop a model that can be applied to different ores and mills.In AG and SAG, the ore itself acts as grinding media, with the finer sizes being crushed by the coarser ones. Surface mechanisms of loss of mass, in which the inner core of the particle remains intact, also take place. In SAG milling, the effect of balls also has to be taken into account. The role of each one of these mechanisms changes with particle size and the model has to account for such changes."

Jan 1, 1991

By Michael S. Moats, Shijie Wang, Timothy Robinson

In 1987, John Schloen published a survey and analysis of copper electrorefining tank room data. Following this paper, a series of copper electrorefining surveys have been conducted and presented at each of the Copper-Cobre meetings over the past 20+ years (1991, 1995, 1999, 2003, 2007, 2010 and 2013). For each of these surveys, William Davenport has been key driving force in the collection and analysis of data. To honour Professor Davenport’s contribution to copper processing, a review of the data was conducted. Historic trends and possible future technologies are discussed.

Jan 1, 2014

By A. P. Annan, C. Vaughan, J. L. Davis

"The increase in the price of gold in the last decade has led to a significant increase in placer gold exploration around the world. Placer deposits occur in depressions along ancient river and stream channels. In many instances these channels have been covered with materials from subsequent erosion or glacial activity. Use of high resolution geophysical techniques to map the bedrock and soil strata can improve the probability of finding the placer deposits. The buried bedrock surface is often the factor controlling deposition. Ground probing radar (GPR) and seismic sounding are complementary high resolution techniques which can be used to map bedrock topography and soil stratigraphy. Current radar instrumentation operates best in coarse grained soils. Penetration depths of up to 30 m have been attained, and stratigraphic horizons have been mapped with spatial resolutions of better than 0.5 m. Although its spatial resolution is considerably lower than radar, seismic refraction achieves superior penetration in electrically conductive environments such as clay and silt soils. The seismic refraction method thus proves to be complementary to the radar method. The seismic reflection technique is analogous to the radar method. Current seismic instrumentation and energy sources however, provide limited spatial resolution and do not permit the use of seismic reflection for reflecting horizons lying at depths of less than 20 m to 30 m.This paper discusses the use of both radar and seismic methods for placer exploration. The radar and seismic techniques, the field methods, equipment, and data displays are presented. Field examples illustrate the high resolution mapping capabilities of the techniques. The radar data agree very well with the borehole data, and in fact they sometimes detect subtle soil strata variations associated with changes of permeability that were not initially observed in the borehole logging. The radar method can give a continuous profile of water table and bedrock in sandy soils. Seismic soundings are necessary to differentiate between the bedrock and water table reflections observed by the radar."

Jan 1, 1987

By R. B. Smith, D. C. Brady

"A review of the major renovation of the fifty-year old C-I headframe facilities at NERCQ's Con Mine, Yellowknife, N. W.T. is provided. The project was complete with only two 3-day shutdowns of the facility .Work consisted of four major phases: structural reinforcement of the adjoining mill building prior to dismantling; relocation of virtually all mine and mill utilities which transited the headframe collar en route from the adjacent powerhouse; dismantling of the entire headframe facility and portion of the mill building, including the removal of asbestos siding; and erection of a new headframe, idler rower, collarhouse and mill wall.This paper describes the work and methods used by NERCQ, J.S. Redpath Mining Consultants Limited, Acres International Limited, and others to bring the project to a successful completion. The history of the project is discussed from the planning phase through construction, including; design, procurement, and construction scheduling. The paper discusses the unique elements of the project, the problems encountered, and the methods used to achieve success.IntroductionThe Con Mine is a 800 tpd gold operation located in Yellowknife, Northwest Territories. Originally owned and operated by Cominco Limited , the Con Mine was sold in December 1986 to NERCO Minerals Company, and officially renamed NERCO Con Mine, Ltd. The Con Mine has been in operation for over 50 years. The first gold brick ever produced in the Northwest Territories was poured at the Con Mine in 1938. The original C-1 shaft was sunk in 1937 to a depth of 235 ft. In 1941 the shaft was deepened to a depth of 950 ft, and the original timber head frame was replaced with a steel structure. Following the discovery of the Campbell Shear in 1946, the C-l shaft was again deepened to its present depth of 2443 ft. Over the years, mine production gradually moved deeper and further from the C-l shaft."

Jan 1, 1991