Search Documents

By Stephen B. Cheeseman

The quantity of data available and the rate at which we access such data are rapidly increasing. Electronic data capture systems, fleet management systems and a host of other technological advancements have created a constant stream of real-time, tactical data. However, are we taking advantage of this data? Are we converting data into useful information to aid in efficient decision-making? Mining operations are struggling with ?information overload?, finding it difficult to extract the benefits from vast stores of data. Without the necessary tools to facilitate a data filtering and information reporting process, most operations revert to old practises such as re-entering data into multiple spreadsheet reports. As a result, the ability to make effective use of data still eludes many mining operations. Some operations have taken audacious steps to rectify this situation. The De Beers Venetia mine in South Africa has implemented an integrated mining information technology solution that transforms their data into practical, usable information allowing staff and management to make decisions that improve efficiencies and reduce costs. In the absence of quantitative justification or ROI, De Beers took a risk in implementing change. Today, they are realising the benefits. This paper will unearth the information technology issues that surfaced during the Venetia implementation, then identify the benefits De Beers has obtained from deploying an integrated mining information technology solution at the Venetia mine.

May 1, 2002

By Fadi Layyous Gedeon, David Hatton, Solomon Mogashoa, Tuhin Banerjee, Faisal Aljohani

The adoption of innovative technologies in mineral processing often raises concerns about complexity and integration. However, Woodgrove’s Direct Flotation Reactor (DFR) technology at Barrick’s Jabal Sayid copper concentrator provides a different perspective. This paper outlines the smooth integration of DFR technology from piloting to full-scale commissioning, showcasing how easily the cells were brought online. Installed in a cleaner scalper role, DFR cells at Jabal Sayid upgrade re-ground rougher concentrate to final concentrate in one stage. Despite processing challenging ore, the DFR cells delivered concentrate grades that consistently exceeded expectations. The commissioning process was straightforward with minimal hurdles, highlighting the technology's user-friendly nature. This paper advocates for a shift in perceptions about new technologies in mineral processing. The success of DFR technology at Jabal Sayid demonstrates that “different” doesn’t mean “difficult.” By focusing on ease of commissioning and operational integration, innovative solutions can enhance processes, improving efficiency and productivity in the mining industry.

May 4, 2025

By A. Warczok

The mechanisms and kinetics of copper oxidation and reduction have been investigated in small scale thermal gravimetric experiments as well as in laboratory pilot scale, packed bed reactors. With blister copper flowing gravitationally down through a packed bed of ceramic particles, counter-current to low oxygen containing combustion gases, the rate of oxidation was found to be very high due to the large surface area created. Similarly, reduction by flowing copper through a packed bed of charcoal lead to rapid de-oxidation. Based on these laboratory measurements, fundamental rate data have been obtained. Modeling of industrial sized packed bed reactors using the laboratory results, opened up the possibilities of developing a new, very intensive, continuous process for copper fire refining. The developed mathematical model together with a computer process simulator, allowed for the design of the industrial-pilot installation to be built and tested at the ENAMI Paipote smelter in Chile.

Jan 1, 2007

By J. W. G. Hannon

FOLLOWING the experimental work of Denny, Robson, and Irwin, and the clinical investigation by Crombie and Blaisdell, an investigation of aluminium therapy was begun at Washington, Pa., which is situated in a very large industrial section of the State. Some of the men to be studied were from plants manufacturing silica brick, refractories used in steel and glass manufacturing, and semi-porcelain table-ware; others were workers in foundries, sand blasters, and men engaged in the quarrying of ganister rock. This group of workmen gave an opportunity to study the effects of aluminium on various types of silicosis which differed somewhat from that found in hard-rock miners. EXPOSURE In their occupations, the men studied were exposed to silica dust concentrations ranging from 17 to 97 per cent free silica. In the silica brick industries, the unfired product averages 96 per cent silica in the form of quartz, whereas the fired brick contains 50 to 62 per cent cristobalite plus 17 to 30 per cent tridymite, forms of silica that, on account of their higher solubility, are more toxic than quartz. The operational dust counts in the plants varied from 15 to 9,500 particles per c.c., and the median particle size from the aerial samples was 1.0 micron for the green product and 2.0 microns for the fired product. The length of exposure varied with the occupation as well as with the individual plant, but disabling silicosis could be produced in less than four years in certain exposures. The average time needed to produce radiological silicosis in those susceptible to this disease was eight years. Some of the men in our series of cases have been treated as long as fifteen years after exposure had ceased, and have improved under treatment.

Jan 1, 1944

By G. Ergin

The interactions taking place between Al-Mg alloys and the bed media during aluminum filtration are not yet well understood. These interactions were studied using the infiltration technique. The reaction interface was analyzed using different techniques such as SEM and TEM. Only spinel formation was observed at the interface regardless of the type of alumina and contact time. This paper discusses the results of the study.

Jan 1, 2004

By Siavash Zamiran, Abdolreza Osouli

"One of the most concerns of room and pillar mining system is subsidence of the ground surface due to coal mining particularly in room and pillar mines. Subsidence of ground surface is a result of floor, pillar, or roof failure of the mine. At the same, due to many difficulties associated with surface disposal facilities of coal refuse, some mining companies are trying to use underground space as a disposal storage place. In this study, stability and subsidence analyses of an underground coal mine located in the Illinois Basin are conducted. This room and pillar mine was abandoned and later on was used as a storage place to accommodate the coal fine refuse with slurry backfilling method. The geological stratigrophy and geomechanical properties of the mine floor and roof were collected. Floor and pillar stability analyses were conducted for areas with various extraction ratios. The stability of the mine was evaluated both prior and after slurry backfilling. The floor and pillar stability analyses results of the mine due to moisture exposure after slurry backfilling are discussed. The subsidence potential due to mine failure is also evaluated.INTRODUCTIONA typical lithology of coal seams in the Illinois Basin consists of weak underclay stratum. The immediate weak underclay causes frequent floor instability problems in Illinois underground coal mines. There are two different stages in assessing floor stability of the mines where slurry backfilling is planned. The first stage is during the mining operation when weak underclay layer squeezes under pillar stress and results in punching or bearing capacity failure. The second stage is after slurry backfilling. During this stage, the slurry material soaks non-durable floor layers and causes strength reduction in floor material. Pillar stability conditions should also be taken into account during both the operational period and after the slurry backfilling."

Jan 1, 2015

By K. D. Watson

"THE Mindamar zinc-lead-copper mine, owned by Mindamar Metals Corporation Limited, is at Stirling in Richmond County, near the south-eastern shore of Cape Breton Island, Nova Scotia (Figure I). It is connected by several roads with the Canadian National railway at Sydney and St. Peters.The deposit is said to have been discovered around 1895 as an outcrop in the bed of Copper brook, but the details are obscure. Not until 1925, when it was optioned by American Cyanamid Company, was it developed underground. Between 1927 and 1938, the 1-nine was operated intermittently by The British Metal Corporation (Canada) Limited, and yielded approximately 200,000 tons of ore averaging about IO per cent zinc, 2 per cent lead, I per cent copper, and small quantities of silver and gold. In December 1950, Dome Exploration (Canada) Limited made an agreement with Mindamar Metaî Corporation Limited, which was exploring the old mine, to assume management and prepare the property for production. Production started in April 1952 with a new mill and a new four-compartment shaft, and between that time and the end of 1954 it has totalled 545,347 tons of ore averaging 5·89 per cent zinc, 1·35 per cent lead, 0·66 per cent copper, 0·032 oz. gold, and 2 151 oz. silver.The Mindamar orebodies are irregular lenses and large veins lying within a wide, almost vertical shear zone of remarkable persistency. The shear zone consists mainly of well-foliated sericite schist derived from siliceous siltstone, and it contains a vast amount of dolomite and magne-site of hydrothermal origin. Most of the ore is extremely fine-grained and some of the high-grade material has a conspicuous thinly layered structure. The metallic minerals, in order of decreasing abundance, are pyrite, sphalerite, chalcopyrite, galena, and tennantite; the gangue minerals, in the same order, are dolomite and magnesite, quartz, sericite, talc, chlorite, barite, albite, and alunite.The geological setting of the deposit is shown in Figure 2. Except along streams and lake shores, almost all of the bedrock is concealed by glacial drift. The group of rocks in which the deposit occurs consists principally of greywacke, siltstone, tuff, brecoia, and Javas, and has been correlated lithologically with the Bourinot group of Middle Cambrian age. A short distance west of the mine, these rocks are in contact along the Stirling fault with conglomerate, arkosic sandstone, and quartzite belonging to the Middle River group of Silurian or Devonian (?) age, which elsewhere in the area overlies the Bourinot group unconformably. The large bodies of granitic rocks in the region, and the large lenticular masses of diorite and quartz diorite associated with them, have been assigned by Weeks (5, pp. 68-69) to the Devonian."

Jan 1, 1949

By A. Torkian

Process water from production of concentrates in Meydook copper sulfide mine is transferred to the 8.3 million m3 tailings dam and a water retention pond after initial thickening. Elevated concentrations of heavy metals, sulfate, and TDS and decrease in pH as well as seepage into the aquifers have been the concern of the regulatory agencies since the start of activities. In this paper the results of a 6-month monitoring program from 4 wells are presented. The wells were located approximately 1.5 km from downstream of tailing dam (0.4 km from water retention pond) as well as upstream background well (2.28 km from water retention pond and 1.27 km from tailings dam). The objective was to study possible effect of accumulated tailings on the groundwater resources. Water levels in sampled wells were on average between 20 and 40 m. Results showed high levels of lead (5 ppb), copper (0.17-0.46 ppm) and selenium (73.1- 29.1 ppb). High levels of selenium and lead were partly due to natural geological settings of the area with high levels present in unaffected soils in the vicinity including water wells of villages upstream of mining operations. High copper levels were attributed to both mining operations as well as deposition from particulate air deposition onto the soil and transport to ground water by rain.

Aug 1, 2013

By E. Ghali, C. Su, G. Houlachi

"The influence of lead ions on zinc electrowinning process was investigated by means of electrochemical noise measurements (ENMs) and cyclic voltammetry in conjunction with scanning electron microscopy and X-ray diffraction. All electrochemical experiments were performed in sulphuric acid electrolyte containing different lead ion concentrations as impurity. Lead was added in six trace levels between 0.05–0.8 mg/L in the bath. The lead content of the zinc deposits was dependent on the introduced lead concentrations. The overpotential associated with zinc electrodeposition shifted to higher values with the increase of lead concentration in the solution. An appropriate correlation was found between the different concentrations of lead in the electrolyte and the morphology of zinc deposit by ENM. The results showed that the increase of lead ion concentrations is generally accompanied with the decrease of skew and increase of kurtosis values that could be related to the morphology of zinc deposit. Effectively, the morphology changes from well-defined hexagonal platelets to large hexagonal, layered platelets and finally to non-symmetric refined crystalline structure, respectively.INTRODUCTION In commercial zinc electrowinning, zinc oxide is leached from the roasted calcine with an aqueous acid sulfate electrolyte. Then the zinc-rich solution is purified and transferred into an electrolytic cell. During electrolysis, zinc is deposited on aluminum cathode where lead-silver or pure lead is served as anode. Electrodeposition of zinc could be influenced by several parameters such as bath acidity, temperature, current density, the nature and concentration of impurities as well as additives in electrolyte. Metallic impurities play a complex role during zinc electrowinning and they can adversely"

Jan 1, 2016

By H. R. Kempthorne

"The Property of Bevcon Mines Limited, including a recently acquired adjoining south group, occupies an area of 2,625 acres in northeast Louvicourt township, Abitibi county, Quebec. It is situated 17 miles east of Val d'Or at the junction of provincial highways 58 and 59.Gold was first discovered in the area in 1931 by the late S. B. Jowsey on the present property of Buffaddison Gold Mines adjoining to the west. However, it was not until the winter of 1944-45 that diamond drilling encountered encouraging results on the Bevcon claims. During the period 1946-1948 a shaft was sunk to 1,000 feet and considerable development undertaken from the 500-foot to the 1,000-foot levels. Between 1947 and 1950 approximately 24,000 tons of dump ore and 48,000 tons of ore by stoping were milled at Perron Gold Mines. The favourable results of these tests prompted the decision to construct a milling plant at Bevcon. The mill began operating in July 1952, and presently has a capacity of 800 tons per day. In 1953 the shaft was deepened to 1,600 feet and is currently (1955) being driven to 2,225 feet.Total production of gold to the end of 1954 has been 101,024 ounces from the milling of 697,427 tons of ore of an average grade of 0·163 ounces per ton.GeologyThe Bevcon orebodies occur in a granodiorite stock which has an east-west length of approximately 4 miles and a maximum width of 1 1/2 miles. The property covers the central portion of the stock and its contacts with the Keewatin volcanics. Approximately one-third of the northern contact and one-half of the southern contact are contained within the Bevcon claims. The granodiorite has been cut by acid (feldspar porphyry) and basic dykes trending east-west. A younger diabase dyke, 300 feet wide, strikes northeasterly across the property 1,000 feet east of the shaft.The main ore zone, striking east-west, lies between the more northerly porphyry dyke and the north granodiorite-greenstone contact. It has been extensively sheared, fractured, altered, and mineralized by gold-bearing solutions. It is approximately 2,000 feet Jong from the west boundary towards the diabase dyke. The shaft is centrally located and passes through the south contact of the ore zone at the 500-foot level. The zone increases in width and trends northerly with depth, due to the porphyry and greenstone contacts having average dips of 80 degrees and 70 degrees respectively to the north. Thus on the uppermost or 500-foot level the width is 150 to 200 feet, and at the present bottom level at 1,600 feet the width is 400 to 500 feet.Another gold-bearing zone has been indicated 200 to 400 feet south of the main ore zone by limited surface drilling."

Jan 1, 1949

By Bruce Macdonald

Operational monitoring of slope stability can be achieved by space based InSAR monitoring platforms. Natural and man-made rock slopes are monitored using a novel stack-based InSAR method that exploits both persistent point scatterers (PS) as well as coherent distributed scatterers (DS) such as areas of pavement and sparsely vegetated surfaces. The new method, Homogenous Distributed Scatterer (HDS)-InSAR identifies InSAR targets by using adaptive multilooking of statistically homogenous pixel neighbourhoods combined with thresholding the differential temporal coherence of each target candidate with respect to its surroundings. HDS-InSAR preserves PS and therefore forms a direct generalization to our proven DualScale-PSI method. The density of HDS exceeds that of PS by more than an order of magnitude often providing essentially continuous coverage over urban and industrial landscapes featuring a mix of infrastructure with mostly bare soils or rock surfaces. The improved coverage enables better definition of surface motion and underlying geology, which will lead to superior interpretation of the geophysical mechanisms causing the surface deformation, e.g. through improved integration with 3D deformation modeling. We illustrate the performance of our new HDS-InSAR method compared to DualScale-PSI using displacement results from Vancouver, Canada; Bingham mine, USA; and the Palabora mine, South Africa.

Jun 1, 2012

By Lev Filippov, Saeed Farrokhpay

"Flotation process has had less success to recover nickel from laterite ores. Nickel in laterite ores is often finely disseminated in various minerals in very fine size. Therefore, fine grinding should be used to liberate nickel containing particles. Particles resulted from fine grinding are often very fine, and recovery of such particles is generally low using conventional flotation methods. One option to overcome this problem is enhancing the particle-bubble interaction by increasing the particle size and forming flocs. Selective flocculation of fine particle can be therefore the key to enhance the flotation performance of low grade laterite ores.INTRODUCTIONThe majority of the world’s nickel resources occur as laterite ores which are complex, low grade and expensive to treat using conventional smelting and high temperature and/or high pressure autoclave methods (Xu et al., 2013). While about 70% of the nickel resources are contained in laterites, only 40% of the world’s nickel production comes from these ores. Researchers have tried to improve the nickel laterite flotation recovery by using a number of feed preparation techniques. For example, in a study on a laterite ore sample from Australia, flotation tests on a narrow sized fraction of 38-75 µm resulted in only a small increase in the nickel content, from 1.0% to 1.4% (Quast et al., 2015a). In fact, no physical separation technique (including flotation) has been able to dramatically upgrade nickel in laterite ores (Quast et al., 2015b). Thus the challenge of processing low grade nickel laterite ores still exists. This paper aims to explore the possibility of applying selective aggregation in pre-concentrating of valuable minerals in nickel laterite ores."

Jan 1, 2016

By T. Sugawara, H. Sekimoto

Electrorefining of low-grade copper alloys containing various amounts of nickel, lead, antimony, bismuth, arsenic, selenium, silver, and gold in sulfamic acid media was demonstrated. The copper concentration of the alloys used as an anode was 70–90 wt%. The electrolyte contained 100 g L-1 of free sulfamic acid and 40 g L-1 of cupric ion. Galvanostatic electrolysis was conducted at 200–300 A m-2 in the electrolyte using a low-grade copper alloy anode and a stainless steel cathode at 25C. The terminal voltage was approximately 0.8 V at the start of the electrolysis, although it increased periodically to approximately 2.0 V and then shortly returned to its initial value. Nickel, lead, and arsenic from the anode dissolved in the electrolyte and were removed. Antimony, bismuth, selenium, and silver were removed as solids. Consequently, a dense copper cathode was obtained, and the concentration of copper was evaluated by inductively coupled plasma – optical emission spectrometry to be 99.82–99.99 wt%. INTRODUCTION Electrorefining of copper is conventionally carried out in a sulfuric acid electrolyte using crude copper assaying at 99.5 wt% Cu as the anode (Biswas & Davenport, 1994). Elements more noble than copper do not react anodically, and consequently, they are distributed in anode slimes. Elements less noble than copper dissolve from the anode. Nickel and arsenic are stabilized as aqueous species. Lead, antimony, and bismuth react with water, sulfuric acid, or arsenic acid to form barely soluble compounds; thus, they are distributed in anode slimes. An emerging issue in the electrolytic refining of copper is an increase of impurities in crude copper used as the anode (Moats et al., 2013). This is due to an increase in the content of impurities in copper concentrates as well as an increase in the types of secondary copper feedstocks (e.g., E-Scraps, automotive shredder residues, and smelting residues) treated in the copper pyrometallurgical process. An extreme case is a copper smelter that does not use copper concentrates as feedstocks. In such a process, copper-bearing feedstocks are smelted in a top submerged lance furnace to prepare low-grade copper alloys assaying at 80– 90 wt% Cu (Sekimoto et al., 2013). Such low-grade copper is not acceptable as an anode in the conventional copper electrolytic refining process because it is easily passivated during electrolysis. Consequently, electrolytic copper is produced by leaching the atomized low-grade copper in a sulfuric acid solution with oxygen, followed by electrowinning. However, electrowinning should be avoided whenever possible because the electrical energy consumed in electrowinning is 5–10 times higher than that consumed in electrorefining. Therefore, the development of technologies for electrorefining of low-grade copper alloys is desirabl.

Jan 1, 2019

By V. Fiedler, H. Lachmund, R. Bruckhaus

"After producing some 50 million tonnes of crude steel the two BOF vessels at Dillinger Hüitte steel plant had to be replaced in 2000/01 due to large deformations. The new vessel design was optimised after a number of theoretical evaluations.Refractory investigations were carried out as well as temperature measurements of the shell to provide a basis for selecting a suitable steel grade. This was found in a DH-GTS development - P420M HT - with high strength at elevated temperatures and excellent weldability and made it also possible to build the vessel without any cooling system.After putting the first vessel into operation the metallurgical results showed no remarkable improvement compared to the old vessel, and were therefore not satisfying. With the help of cold model investigations the arrangement of the tuyeres was modified to improve the flow conditions and the interactions between oxygen jet and the heterogeneous plume of the bottom stirring gas. Further optimisations were obtained by a variation of lance tips and a newly developed lime addition model."

Jan 1, 2004

By Mohamed Hamoud

Relative permeability curves represent an important element of special core analyses, but challenges remain in obtaining valid results and the extrapolation and use of existing permeability results is problematic. This situation is compounded in cases where core properties are altered from changes in effective stress. During the production of oil and gas reservoirs, the effective stress changes as a result of changes in pore pressure or temperature. Therefore, changes in rock properties such as porosity and permeability will occur and will consequently influence reservoir performance calculations. An experimental program was carried out to understand the behavior of dense, reconstituted sand samples at low effective stress states. Drained triaxial compression tests were set up to study the effect of stress alteration on relative permeability data through porous media. Initially, a saturation stage was performed followed by isotropic loading to bring the core sample to reservoir fluid and stress conditions. Then, while axial (deviatoric stress) loading was applied to the sample, a series of absolute and relative permeability tests was performed under steady state flow at different levels of strain during pre and post peak shearing stress. The stress-strain behavior results from the study revealed that the absolute permeability decreased during isotropic loading (compaction) and increased during shearing (dilation). However, the shape of relative permeability curve changed from contraction to dilation and showed higher initial kro and the lower initial kro respectively. The goal of this project was to understand the behavior of both absolute and relative permeability at different stresses. It is expected that geomechanical processes will be adopted for special core analyses to support the current integration of geomechanics into reservoir engineering. This will be required if, during SAGD, conventional and/or unconventional reservoir simulation, reservoir engineers implement a proper set of relative permeability data at each in situ state of stress, instead of constant curves throughout the field?s life.

Jun 1, 2012

By E. O. Chisholm

Synopsis The colour changes effected in a solution of dithizone by trace amounts of copper, lead, and zinc mineralization provide a sensitive field test for these metals. The method has been used with success by the United States Geological Survey to trace zinc orebodies under residual soils. The dithizone test is used here on samples of non-residual soil overlying a gold-bearing zone in which the gold is associated with disseminated sphalerite, galena, and chalco-pyrite. A gold-bearing zone was successfully traced under overburden ranging from a few inches to five feet in depth by means of this method. The method may prove useful in guiding preliminary trenching through light overburden, by outlining the extent of copper, lead, and zinc mineralization. Introduction The dithizone test affords a rapid, simple, and delicate test for the presence of zinc in soil and water and is suitable for use under field conditions. It has recently been used with success by the United States Geological Survey to outline a zinc-rich area in the residual soil over a primary zinc deposit in Tennessee. The purpose of the present study was to ascertain whether the method could be used to trace a gold-bearing zone, containing associated zinc mineralization, under shallow, non-residual, glacial overburden. The results obtained indicate that the method can be used to guide preliminary trenching in overburden up to six feet in depth. Tests made of the water near lake-shore outcrops also indicate that favourable prospecting zones may be located from the water, within five feet of the shore. It is felt that this simple field test should find a wider use in prospecting, because, under certain conditions, it can outline favourable zones and thereby reduce the amount of blind trenching necessary. The following pages describe the type of deposit tested, the method used, the .results obtained, and the difficulties encountered by a novice in the use of this chemical procedure. The author is indebted to the officials of Nor-Penn Mines, Limited, for their co-operation while the tests were being made; to the late Richard Bouska, Kenora prospector, for helpful suggestions; and to F. W. McCamus, University of Toronto undergraduate student, who ably assisted with the work.

Jan 1, 1950

By K. Sugawaral, W. Tongampl, K. Hiruta, Takasaki Y., A. Hosoi, T. Katol, A. Shibayamal

Printed circuit boards of discarded personal computers, televisions, mobile phones and so on contain a significant amount of valuable metals. For the recycle of valuable metals contained in the printed circuit board wastes (P CB W), the effect of temperature on chlorination-volatilization of metals under chlorine gas flow was studied. The experimental sample used was powder of two types: crushed PCBW (Sample 1) made from PC and industrial machines, and crushed-combusted PCBW (Sample 2) made from Sample 1. The principal element in Sample 1 and Sample 2 was copper, about 13 wt% and 20 wt% respectively. Sample 1 was composed of pure metals such as copper, tin and lead. In comparison, Sample 2 consisted of oxide metals such as copper oxide, tin dioxide and silicon dioxide. The two samples were heated at predefined temperatures (ranging from 300 °C to 900 °C) in chlorine gas. The chlorine gas flow into the furnace was set at a rate of 100 mL/min. As a result, copper in Sample 1 began to volatilize at 600 °C and completely vaporized at 700 °C. While in Sample 2, copper started to volatilize at 600 °C and reached 100% vaporization at 800 °C. For Sample 1, zinc finished volatilizing at 500 °C, while for Sample 2, zinc volatilization reached only about 80% (maximum). Also, lead, nickel and titanium showed similar results. Consequently the volatilization rate of Sample 1 is higher than Sample 2 and the temperature dependency was verified for copper, lead, zinc, nickel, antimony, titanium and chromium. In fact, the volatilization rate of these metals increased with the temperature. This result reflects the difference between pure metal and metal oxide, as Sample 2 was combusted before the chlorination-volatilization test. Moreover, the chlorination reaction may be accelerated by a reductive atmosphere because Sample 1 contains carbon. In this study, the volatilization behavior of some valuable metals in PCBW by chlorine gas was observed. Further improvement in the rate of volatilization can be achieved by optimizing the experimental conditions.

Jan 1, 2011

By J. H. . MORGAN

Talc-soapstone deposits exist in Patton Township of Quebec and have been mined by Bakertalc Inc. or its predecessors since 1938. The company produces products ranging from purified and micronized talc through to soapstone lumps. The deposits are found within serpentinite dykes and are zoned. Zoning grades from a serpentine core through zones of talcmagnesite, schistose talc and talc-chlorite schist be/ ore reaching the wall rock of quartz-sericite-chlorite schist. Talcmagnesite zones generally comprise 80 to 90% of the mined rock. The serpentinite dykes containing the talc probably were originally post-Ordovician peridotite of the same series that hosts the Eastern Townships asbestos deposits. Alteration of serpentine to talc-soapstone and magnesite apparently resulted through addition of silica and carbon dioxide along shears and fractures. Talc concentrations occur also at the intrusive contact between dykes and wall rock. The present Bakertalc Inc. operation at the Van Reel Mine is being worked from an inclined shaft 200 m below surface. The talc rock undergoes a variety of milling processes, depending on its particular market, be/ ore being bagged and shipped.

Jan 1, 1984

By K. G. Markkola

Since 2005, Compafifa Contractual Minera Candelaria (CCMC) has defined various strategies which aim to optimize the usage of the available energy in each of the SAG grinding circuit modules (SABC-A configuration). For this purpose, the use of larger size balls along with operating with an optimum balls/load ratio has been implemented. Additionally, in the ball mills, the amount of balls in relation to the equipment's usable diameter has been optimized. In the pebble crushing circuit, the percentage of material passing 12 mm (112 in) product has been increased by 15% by: (1) modifying the crusher mantle profile, (2) implementing a strategy for maximizing the power in each crusher, (3) using continuous improvement tools (Lean - Six Sigma), (4) redesigning SAG mills discharge grates, and (5) changing discharge grates in order to control the crusher feed size distribution profile. All these activities have improved plant throughput by 1,000 t/d with no significant capital investment. As part of the energy consumption optimization study, we have considered determining the optimum operational rate of each SAG mill, in relation to the mill liner life and also the improving the control strategy in conventional grinding.

Jan 1, 2007

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