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By G. R. MANSON

The Brisco Barite Mine lies 70 km south-southeast of Golden, British Columbia. Barile mineralization occurs in a northstriking brecciation zone within Ordovician-Silurian Beaver/ oot dolomites and quartzites. Brecciation was caused by faulting related to the Mount Forster-Steamboat Fault. The main barite vein occupies a fault zone and is up to 12 m wide and over 250 m long. It is light grey to white, fine grained and compact; BaSO4 content is 9/. 70 per cent. Production started in 1945 and has continued to the present. Barile originally was removed from an open pit; later, an adit, begun in 1957, reached more than 240 m along the vein, 15 m below the pit floor. Today ore is hoisted from a decline resting some 37 m below the pit floor.

Jan 1, 1984

By Fathi Habashi

Poland has a unique copper industry. Copper sulphide concentrates are smelted in six shaft furnaces to produce matte and in a flash furnace directly to blister copper. Anodic slimes from electrorefining are treated by a modern technology to recover the precious metals. INTRODUCTION Poland's copper industry began in 1950 when the old and relatively small mines Lena and Konrad, located in Lower Silesia, were drained and recommenced production. In 1957 the industry entered a period of rapid development with the discovery of a rich ore body in the vicinity of Lubin and Polkowice which was the basis for the establishment, in 1961, of the Copper Mining and Smelting Combine (KGHM). In 1991 the Combine was restructured into a state-owned, joint-stock company under the new name of KGHM ?Polska Miedz? (KGHM ?Polish Copper?). It consists of three mines, three smelting and refining plants, and one rolling mill, and produces about 4% of the world?s copper and about 7% of the world?s silver.

May 1, 2001

By L. Gasser, N. Bellinger, H. Awatta, A. Merati

As aircraft age, the extent of interactions between fatigue and other damage mechanisms, such as corrosion and fretting, increases. At present, however, there is no generally accepted methodology within the Aircraft Structural Integrity Program (ASIP) framework to account for the effects of these interactions on life and the residual strength of aging aircraft components. A comprehensive program is being carried out by the National Research Council Canada in collaboration with Analytical Processes/Engineered Solutions, using the Holistic Structural Integrity Process (HOLSIP) to address time and cyclic load issues. This approach predicts the evolution of a discontinuity state in a material from production to retirement. This paper summarizes the results of a study on the 2024-T3 aluminium alloy in different forms (clad and unclad), thickness, and specimen geometry. This study consisted of identifying the microstructural features associated with crack nucleation sites and relating them to the testing parameters and fatigue life. Several coupons were fabricated and fatigue-tested. The fracture surfaces were carefully examined, and the physical characteristics of the microstructural features found near the crack nucleation sites were analyzed. Effect of stress level, loading direction, coupon geometry and surface condition on the number of crack nucleation sites, and fracture origin size has been discussed. Four distinctive mechanisms were found to be responsible for crack nucleation: for unclad materials constituent particles, oxide residue, surface irregularities and for clad samples the clad layer was the sole fracture origin.

Jan 1, 2006

By G. W. Clark

"The mining of the ore bodies at Rabbit Lake has in the past been by the open pit method. This method is presently being used to develop the B-zone and will continue into the future with the development of two smaller ore bodies, the A-zone and D-zone. The Eagle Point orebody will be developed by an underground method which will provide production and employment into the next century.The ore bodies at B-zone, A-zone and D-zone are unique in that they are located under Wollaston Lake. To permit mining by the open pit method a steel-celled dyke has been constructed around the north end of the B-zone. This same dyking method will be used for the A -zone and D-zone. INTRODUCTIONMine development at Rabbit Lake commenced in 1970when a detailed engineering feasibility study established the viability of the Rabbit Lake deposit. In 1972 construction of the mill and camp site began. Construction materials were seasonally hauled to the site over a winter road until November 1973when the government of Saskatchewan completed an all-weather road to within six miles of the operation.In October 1974, stripping of the Rabbit Lake open pit began with the removal of overburden and lake bottom sediments from the previously drained Rabbit Lake. The first ore was processed by the mill in June 1975and by October the mill was producing three million pounds per year. The design capacity of five million pounds annually was first achieved in 1977 and maintained until 1981, when lower ore grades resulted in lower production rates .It was clear when mining at Rabbit Lake began that, without additional reserves, the Rabbit Lake operation had a life of less than 10 years. Exploration, therefore, continued in the immediate area in an attempt to discover additional uranium mineralization."

Jan 1, 1989

By T. Kho, W. Zhang, M. E. Reed

The control of flash furnace heat balances is critical. Suspension smelting control and stability comes from stable operation of the heat balance, and this leads to a stable reaction shaft exit temperature. A number of flash furnace operations have been reviewed to determine if the application of this approach is beneficial for their operation. The cause and effect relationship between reaction shaft exit temperature with uptake and throat buildup is being enhanced with this work program. Our operating personnel are exposed to the operational hazards of cleaning this buildup from the throat and it is imperative that as an industry we continue to look for repeatable solutions. WorleyParsons has reviewed operational data from a number of flash furnaces and looked at the possible improvements that can be made to decrease variation in the reaction shaft exit temperature. The data assessed for each operation illustrate the need to fully understand the process inputs to the particular operation and to ensure that the control changes are correctly impacted. In the plant data that have been assessed for a number of operations combinations of feed changes and inappropriate process decisions have lead to changes in reaction shaft exit temperature which impact the overall furnace operation and the uptake shaft condition, and ultimately the boiler. INTRODUCTION In 2016 WorleyParsons jointly prepared a paper outlining the effects of heat balance control on the Olympic Dam flash furnace (Reed et al, 2016). That paper investigated the importance of heat balance control in flash furnaces and demonstrated the changes made at the Olympic Dam operation to control the heat balance in the furnace and the impact that change had. The operation is still using the tool to assist in trouble shooting performance and pinpointing problems that may lead to issues in the furnace throat and Waste Heat Boiler (WHB). As a result of the interest in the methodology and due to the issues surrounding safety and process performance caused by WHB throat buildup and damage, WorleyParsons approached a number of flash furnace operators to discuss the application of the approach at their operations.

Jan 1, 2019

By A. R. Trusiak, C. Bazin, D. Hodouin

"The On-Stream Analyzer has proven, and is still proving to be, an extremely valuable tool for the control of flotation circuits. This paper examines the possibility of going further in the utilization of the analyzer results by using a real-time material balance program to calculate the mass flow rates within the streams of a circuit for process control, analysis and optimization as well as for the detection of sensor malfunction. The material balance algorithm improves measurements and give good estimates of unmeasured variables during normal operating conditions. The potential and limitations of the method are illustrated using results of an application to the Line 3 flotation circuit of Brunswick Mining and Smelting, New Brunswick.IntroductionThe On-Stream Analyzer (OSA) has gained, over the last two decades, the status of key instrument for the control of flotation plants. The OSA is currently used in almost every sulphide flotation plant and its application in oxide mineral flotation plants isincreasing. Commercial OSAs include a sampling system that collectssamples from various streams of a circuit and exposes thesamples to an X-ray beam. The sample then generates X-ray pulsesthat are converted into assays using multilinear regression programs(Leroux and Franklin, 1994). The estimated assays arepassed to the flotation operators via operator consoles, or to controlloops of various degrees of complexity (McKee, 1991), whichmanipulate reagent addition, aeration rate or froth thickness toensure an adequate operation of the plant. Although this applicationrapidly pays for the purchase of the OSA, one should ask:""Could we get more from the OSA?"""

Jan 1, 1995

By J. Ling, J. Xiao, A. R. Laplante

"The most challenging gold gravity separations occur when gangue has a high s.g., gold is fine, or a combination thereof This paper examines such separations, and evaluates the performance of a 3-in Knelson Concentrator at various rotation speeds, a 4-in SuperBowl, and a laboratory Mozley Multi-Gravity Separator (MGS). Synthetic feeds, primary cyclone underflows and flash flotation concentrates are tested.It is concluded that higher rotation speed are mostly useful for very fine (< 3 7 µm) gold recovery, with potential loss of recovery in the 37-212 µm range. This problem is traced to the collapse of the flowing film at higher Gs, which hinders the percolation of particles of intermediate size. Increasing fluidization water flow can alleviate this problem, but the recovery of very fine particle then drops. The MGS does not operate with the same principles, and can achieve good to very good recoveries of very fine to fine gold particles, but the unit has a high cost to capacity ratio, and there is no evidence yet that it can yield smeltable concentrate grade or a concentrate that can be upgraded with a shaking table.IntroductionThis presentation is a sequel to similar CMP presentations of the past eight years; all focused on practical aspects of gold recovery. The first hard rock application of the Knelson Concentrator (Laplante et al, 1990), studies of the grinding and classification behaviour of gold and other malleable metals (Banisi et al, 1991; Laplante et al, 1995), the development of a 3-in Knelson based methodology to study gold gravity circuits (Laplante and Shu, 1992), a comparison of the Knelson and Falcon (Laplante, Laplante et al, 1993), the presentation of a test to determine the amount of gravity recoverable gold, or GRG (Laplante et al, 1996), and the use of synthetic materials, in particular tungsten, to mimic gold (Laplante et al, 1995) were presented. A summary of many practical implication of the McGill research was presented in 1994 (Laplante). Whereas gold gravity recovery was less popular and largely jig-based (in North America) at the beginning of the eighties, many gold plants now incorporate a gravity circuit, and the Knelson Concentrator is the most commonly used unit."

Jan 1, 1998

By W. T. Gotheridge

The principal sources of coal-dust underground are, of course, coal, and the working of coal. Coal-dust is most dangerous when it is in the finest state of division. This class of dust is found mostly on the roads, being blown or shaken off the loaded trams in transit, or carried in suspension by air currents. The air current passing from the working faces may also carry dust in suspension into the return airway, and the air current from the surface may carry dust from the shakerscreens into the intake airways. The mosl dangerous dust we have to contend with is, (a) that which is most finely divided, and (b) that which contains the most volatile matter, including the inflammable occluded gases, and also oxygen absorbed from the air. According to experiments, coal-dust in a fine and dry state would intensify an explosion, in air free from fire-damp carrying in excess of 3 ozs. of fine dust or 6 ozs. of coarse dust per cubic yard. The volatile matter in the dust must be between 12 and 31 per cent. in the ash-free coal, the latter percentage giving the highest flame velocity. It is vary difficult to propagate flame where coal-dust contains a large percentage of stone-dust, (say 50 per cent.). Shale-dust or other incombustible dust containing no volatile hydro-carbons or carbonaceous matter will prevent the extension of an explosion if mixed with coal-dust in proportion of say 70 per cent., and if the dust is finely divided and dry.

Jan 1, 1924

By S. Litke

Elemental sulfur was stockpiled at the Mount Polley Mine for use as a source of sulfuric acid as part of research into leaching copper from oxide ores, but the project did not proceed beyond an initial pilot- scale evaluation. Since placement, the sulfur has oxidized and some sulfuric acid leached into the underlying rock. The reaction of the acid with these underlying materials has been studied as part of an evaluation of the effects of leachate from the pile. The rock underneath the sulfur pile is composed dominantly of primary and secondary alumino-silicates with less than 1% carbonate (calcite) and iron sulfide (pyrite). In its unaltered condition, the rock is classified as non-acid generating. Conceptually, it was expected the sulfuric acid would be neutralized by the rock to varying degrees resulting in a series of pH-controlled weathering fronts progressing from leached near the contact with the sulfur pile (pH <3), to active neutralization by silicates (pH 4–5), to active neutralization by carbonates (pH >7). The rocks underneath the pile were sampled to determine the extent to which the rocks had reacted and their long-term stability after removal of the acid source. INTRODUCTION When rock is blasted and excavated to facilitate mining ore, it is typically placed and stored on the surface in piles. The resulting drainage may have a neutral to basic pH (i.e., non-acidic drainage) or a low pH (i.e., acid rock drainage, ARD) depending on the mineralogy of the rock being stored in the piles. Acid- base accounting (ABA) can be used to characterise the two types of rock: potentially acidic drainage generating (PAG) and not potentially acidic drainage generating (NAG) (Price, 2009). According to Price (2009), NAG is defined as having an excess of neutralization potential (NP) in the rock in the form of calcium carbonate-like minerals when compared to acid potential (AP), i.e., a Neutralization Potential Ratio (NP/AP = NPR) greater than 2.0, whereas PAG is classified as having an excess of AP (i.e., an NPR less than 1.0). This is a conservative estimate and may be slightly modified depending on the mineralogy at specific mine sites. Rock with an NPR of 1–2 is also capable of generating acid (Price, 2009) and, depending on the mineralogy, may also be classified as PAG. Drainage from PAG material can generate acid immediately, or many years after it has been exposed to surface conditions. Disposal techniques depend on the category (i.e., NAG or PAG) and reactivity of the rock stored in the piles.

Jan 1, 2019

By Z. Tang

A collaborative project was performed between NRC Institute for Fuel Cell Innovation and MagPower Systems Inc, to develop a cost effective fabrication process to manufacture the anode for magnesium-air fuel cell with improved performance. A novel fabrication process was developed, which resulted in a porous microstructure with increased surface area, instead of the traditional solid structure. This porous anode greatly increased power density in the magnesium-air power source. This fabrication process is very simple and cost effective. Especially, this process makes it convenient to incorporate different alloying additions, as well as hydrogen inhibitor and electrolyte management additive into the anode. The anode composition was designed so that micro galvanic cells were formed as current is drawn out of the fuel cell, and resulting increased dissolution rate of Mg. It is feasible to incorporate hydrogen inhibitor and electrolyte management additive into the porous anode, and the anode with some kinds of inhibitors exhibited improved electrochemical performance. This paper describes the microstructure and electrochemical performance of anodes with designated porous structure and alloying additions. Furthermore, quantitative kinetics analysis of the obtained I-V curves and electrochemical impedance spectroscopy were carried out to clarify the mechanism.

Jan 1, 2005

By C. -G. Berg, J. T. Tuominen

Since the beginning of the 20th century, energy efficiency in copper smelting has been improved by a factor of 30 as a result of adopting autogenous smelting processes with more and more efficient waste heat recovery systems, increasing use of oxygen enrichment and countless smaller improvements. Nevertheless, energy in the form of electricity and fuels continues to be the biggest contributor to smelter operating cost. Metallurgists around the world are under constant pressure to find ways to save those precious megajoules wherever they can. One area that is often neglected is the removal of water contained in concentrates. Copper flotation concentrates, as delivered to a smelter, typically contain some 8–12% moisture. This moisture must be removed and the only way to do this is by evaporation, which consumes a lot of energy. Several studies have shown that the most efficient way of removing this moisture is to use a steam- heated indirect dryer—the least efficient way being the feeding of wet concentrate directly into a smelting furnace. Even in the most efficient smelters that employ modern steam drying, the energy needed to remove the moisture from the concentrates constitutes over 15% of the total energy consumption of a smelter – acid plant complex. The major steps that have been taken in the past to lower the energy consumption of moisture removal are the use of drying in general and the adoption of steam drying. The energy efficiency of concentrate drying has been improved by 25% over the last 20 years. The latest giant leap in this area, the Kumera Heat Recovery Dryer, is the result of Kumera’s long-term development in improving the efficiency of concentrate drying. The Heat Recovery Dryer is a novel application of steam drying that uses the waste heat from dryer exhaust gas for drying concentrates, thus, cutting the energy consumption by a further 30%. This paper discusses energy consumption in copper smelting in general and analyzes the energy consumption of concentrate drying in detail. Different dryer types are compared especially from the perspectives of energy consumption and environmental emissions. Applicability of different energy sources for drying is evaluated and discussed. The principle of the Kumera Heat Recovery Dryer is presented along with results from extensive continuous pilot plant tests. Potential applications and the feasibility of Kumera Heat Recovery Drying technology are discussed.

Jan 1, 2019

By M. S. Hedley

"The Lucky Jim mine is at Zincton in Slocan mmmg division; on the Kaslo-Nakusp branch of the Canadian Pacific railway. It is owned and operated by Zincton Mines; Limited; a subsidiary of Sheep Creek Gold Mines; Limited. The mine is far in the lead in the production of zinc in the Slocan. Its recorded production from concentrates and shipping ore was 102; 260; 191 pounds of zinc to the end of 1945.GENERAL GEOLOGY With the exception of acidic dykes the rocks near the Lucky Jim mine belong to the Slocan series, which is Triassic in age and consists principally of argillaceous rocks. It disconformably overlies greenstones of the Triassic Kaslo series about 3 miles to the northeast, and is cut by granitic rocks of the Nelson batholith 5 miles to the southeast.The sedimentary rocks in this area are best referred to on the whole as slates. They lie within the more fissile basal part of the Slocan series. The term 'slate belt' conveniently distinguishes this area of rocks characterized by slaty cleavage from the more massive argillites that are more characteristic of the Slocan as a whole. The contact between the slaty and massive argillites lies ½ mile southwest of the mine."

Jan 1, 1954

By K. Hashiba, Y. Z. Liang, K. Fukui, M. Koizumi

"Efficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Development and modification of the rock drills based on test data are timeconsuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved. The objective of our research project is to construct a new realistic numerical model of continuous percussive drilling, which is based on the previous Okubo-Nishimatsu’s model. In this study, the parts of the previous model involved in stress wave propagation and attenuation were modified. The two models were prepared for HD712 hydraulic rock drill mounted on crawler drills and HD210 hydraulic rock drill mounted on drilling jumbos. Stress wave propagation was computed with the discretized one-dimensional wave equation. The calculated results were compared to the stress waves measured on a rod during percussive drilling. In both models for HD712 and HD210, the measured stress waves can be reproduced with the one-dimensional model of the same acoustic impedance as the actual piston, shank rod and rod combined with the CI+spring model as a rod joint. The calculated results indicate that the spring constant in the model of a rod joint needs to be set appropriately depending on drilling conditions. INTRODUCTIONEfficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Components related to the percussive drilling are a drill body, a piston, a shank rod, rods, rod joints, a bit and rock. The piston in the drill body is reciprocated by hydraulic pressure and collides with the shank rod a few thousand times per minute. Stress waves generated by the collision propagate and attenuate in the rods and rod joints, and then reach the bit. The bit penetrates and crushes rock. During percussive drilling, the components mutually affect each other and self-induced oscillation occurs. The number of blows and the rate of penetration are determined by the practical drilling conditions such as hydraulic pressure, thrust force, number of rods and mechanical properties of rock. Development and modification of the rock drills based on test data are time-consuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved."

Jan 1, 2015

By V. V. Zubkov

The systems of geophysical monitoring have been already put into operation at coal mines and ore mines. Since at present it is rather difficult to conduct mine experiments; it is necessary to start a new step in joining of geomechanics and seismic. The linking geomechanical and geophysical monitoring at coal mines and ore mines today became possible due to progress in development of numerical methods of modeling of stress state and technology for processing of seismic information. This paper describes one potential step in linking geomechanical and seismic monitoring at coal mines and ore mines.

Aug 1, 2013

By Derek Apela, Coralee Heske, Bunyamin Kahraman, Muhammad Adi

Effective blast fragmentation is essential in underground mining, as it directly influences downstream processing efficiency and operational expenses. This study investigates the application of Non-Newtonian Fluids (NNF) as stemming materials, presenting a novel method to enhance energy confinement, minimize environmental impact, and optimize blast performance. NNFs exhibit shear-thickening behaviour, enabling them to transition between fluid-like and solid-like states under stress, which renders them suitable for regulating explosive gas ejection during blasting. Field trials were performed by Vale Base Metals in Thompson, Manitoba, in their underground nickel mine to evaluate conventional slag stemming against NNF-based stemming in production-scale blasts. Emulsion explosives were employed, and blast performance was assessed through velocity of detonation (VOD) measurements, vibration monitoring, and AI-assisted fragmentation analysis using WipFrag. Preliminary results indicate that NNF stemming improves fragmentation, resulting in a reduction of D50 by as much as 38%, enhances energy confinement, and may decrease the incidence of hole plugging and re-drilling in subsequent blasts. This study presents an alternative to conventional stemming methods, highlighting potential advantages for enhanced safety, efficiency, and sustainability in blasting operations. Additional research and field trials are necessary to improve implementation protocols and facilitate the widespread adoption of this unique method in the mining sector.

May 4, 2025

By I. H. Warren, F. A. Forward, A. Vizsolyi

"Observations are reported on the pressure leaching of material produced by subjecting chalcopyrite to two types of heat treatment. Calcination of the mineral at 825°C, in the absence of oxygen, induces some sulphur loss by volatization, producing a material from which copper can be leached more rapidly than from chalcopyrite. Treatment of the mineral with elemental sulphur at 475°C leads to sulphur uptake accompanied by a change in mineralogical structure of the chalcopyrite. Copper is prefer-entially and rapidly leached from the sulphur-treated material. A tentative explanation of the sulphur-chalcopyrite re-action is presented."

Jan 1, 1968

By Kevin J. Melong

"Redpath Canada Limited and joint venture partner Thyssen Mining and Construction Canada have recently completed the sinking of the Scissors Creek service in Saskatchewan through its joint owned company, Associated Mining Construction (AMC). The Scissors Creek service shaft was sunk at Nutrien’s Rocanville mine. The following paper outlines the shaft sinking plant and the methodology related to sinking and shaft lining. KEYWORDS Hydraulic shaft jumbo, Hydraulic shaft mucker, Potash shaft sinking, Shaft lining, Sinking galloway INTRODUCTION The sinking and lining of shafts at mines to access mineral deposits has always been one of the great mining challenges for owners, engineers and contractors. Over the course of history in Canadian mining, the sinking of potash shafts through the notorious Blairmore formation of Saskatchewan has proved to be some of the most challenging shaft sinking projects on record. There is no doubt that today’s shaft sinking business demands the utmost in safety performance while delivering projects within schedule and budget. Given these requisites, Redpath and TMCC (executed under the joint venture company, Associated Mining Construction or AMC), were taxed with developing the shaft sinking system to deliver this program in the safest and cost effective manner, with due regard to schedule and quality. Traditionally the potash shafts sunk in Saskatchewan involved a significant level of manual labour, owing to the methodology of excavation by means of chipping the frozen shaft sections with hand held pneumatic machines, and manually placing tubbing segments or steel liners of the shaft lining system. Most certainly, the AMC team wanted to make a step change from those earlier sinking programs and develop systems for sinking this potash shaft that removed the high level of manual work, thus making this project inherently safer, while endeavoring to sink more efficiently. With that in mind, the team embarked on a design program to improve its overall shaft sinking systems without the requirement for excessive capital and methodology flexibility to adapt to potential changing conditions expected to be encountered during shaft sinking. This was especially important should the new approach be met with less than expected success, and retrofitting of the system was required. The concepts were developed to provide for a much improved work environment, while easing the manual labour burden on the workers with innovative equipment and approach to the work."

Jan 1, 2019

By Terry Gerritsen, Sylvain Picard, Bruce MacKay

Virtually all new technologies require a control system. Any intense process has many process variables that react quickly making manual control difficult. Control system design has a significant impact on the success of a plant especially during ramp-up. New technology projects are particularly sensitive to control system design as the process response is unknown. This paper discusses the important factors encountered in the design of a control system for a new technology. Examples are given of successful new technology plant start-ups where tight coordination of the process control system implementation, process design and selection major equipment led to rapid ramp-ups.

Jan 1, 2011

By CIM Standing Committee

The CIM Definition Standards on Mineral Resources and Reserves (CIM Definition Standards) establish definitions and guidance on the definitions for Mineral Resources, Mineral Reserves, and mining studies used in Canada. The Mineral Resource, Mineral Reserve, and mining study definitions are incorporated, by reference, into National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101). The CIM Definition Standards can be viewed at mrmr.cim.org. Readers should be aware that reports written by persons issuing technical reports that disclose information about exploration or other mining properties to the public in Canada are governed by a number of securities regulations.

May 10, 2014

By M. W. Bartley

"The Steep Rock iron mine is 141 miles west of Port Arthur, Ontario, and 50 air miles north of the Vermilion iron range in Minnesota. The property lies 27'2 miles north of the village of Atikokan on the south line of the Canadian National railway.The orebodies underlying the bed of Steeprock lake, since de-watered, were known to exist 60 years ago. References to the possibility of iron ore at this location were made in early geological papers and reports. In 1937 the locations of the orebodies were determined by dip-needle surveys, and from 1938 until 1943 diamond and churn drilling were carried on to prove their extent and configuration. It was found that the ore, in addition to being associated with definite types of wall-rock, was controlled by structural features, such as faulting and brecciation. From this geological knowledge the presence of other deposits has been inferred, and these are now being explored and developed.Production at the property commenced in October 1944. During that season 17,000 gross tons of ore was shipped. In 1945, 506,000 gross tons and in 1946, 830,000 gross tons was mined and shipped. In 1946, 164,000 gross tons additional was placed on stockpile for future shipment.TYPES OF 0REBODIES AND MINERALIZATIONThe orebodies at Steep Rock iron mine are tabular. They have an average width of 250 feet, lengths up to 5,000 feet, and persist to known depths of 1,200 feet. They are replacement deposits in brecciated carbonate rock at the contact of underlying pseudo-limestones and overlying volcanics. The ore is composed of hematite and hydrous hematite in the form of goethite, turgite, and limonite. These minerals replaced the brecciated host rocks metasomatically as a result of hydrothermal action. The replacement followed a definite structural pattern along the unconformable contact between the sediments or other rock (now replaced by carbonate) and the volcanics, subsequent to disturbances in the form of minor faulting and shearing. The faulting and shearing provided the channels through which the replacing solutions percolated. It is believed that the late basic intrusions outside the ore zones were genetically responsible for the introduction of the ore-bearing solutions."

Jan 1, 1954