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By G. W. MacLeod

The iron ore question in this country has been widely discussed for many years, but only recently has its real significance becoming generally understood. The exhaustion of the old Helen mine, in 1918, marked the last phase of hematite production in Ontario, and with the closing of the Magpie mine in 1921 , Canada ceased to be a producer of iron ore. For the past three years every ton of ore used in Canadian blast furnaces has been imported. In a recent issue of the Engineering and Mining Journal-Press, Arthur B. Pearsons, Assistant Editor, makes the following statement : Iron dominates the world. Some contend that coal is more vital. be-cause heat is needed to make iron and steel. But there are other sources of energy, more convenient and less costly and it is only a question of time when progress in hydro-electric development will have reached the point where coal will be but an incidental source of power and heat. Even more direct means than the generation of electricity by hydro-power eventu-ally will be developed by making available the latent energy of the sun. But iron; Science gives not the vaguest suggestion that anything will dis-place iron and steel as the most essential material tool of modem civiliza-tion. ? Hardness, tenacity, malleability-it possesses all these in unique de-gree. These are some of the qualities that make steel and iron indispensable in modern industry. The domestic consumption per inhabitant of the United States has climbed uniformly from 0.18 tons in 1900, to 0.36 tons in 1922. New kinds of machines and new types of structures are being devised every year; and steel or iron is the basis of most of them." It is unlikely that the Ontario Government were actuated by this motive when they appointed the Iron Ore Committee to investigate and report on the iron ore situation, nevertheless, these facts must have influenced them in some degree.

Jan 1, 1924

By Leslie B. English

"HistoricalWHILE DIGGING caves and underground passages for living quarters, primitive man must have had some means of illumination. Most likely he used pieces of wood or slim bundles of reeds or grasses as torches, perhaps steeped in animal fats to give more light. If this is so, we may accept these as the first means of underground illumination. Very little was clone to improve lighting devices for many generations, but slowly there was developed a fount holding fatty oils, with a spout in which was inserted a form of wick.Actual mining. for metals first of all, was started about 3,000 B.C. Some of the old Greek and Roman records refer to the use of torches underground, and some evidence of clay lamps has been found. Candies came into use some time during the first century A.D. When coal mining began about the 14th Century in England, candles were used for illumination because of the ease of manufacturing and handling them. Open oil-lamps came into use early in the 16th century -Agricola, in his De Re .Metallica, written about 1540. pictures a miner with such a lamp. However, the expense of these was so great that candies still continued as the general means of underground lighting.Unfortunately, as miners went deeper underground, they encountered a mysterious gas which. upon coming in contact with open lights, flamed violently, resulting in explosions and accompanying loss of life. The first reference to the results of these gas explosions appeared in 1621. No help seemed to be available. The gas was given off when the coal was mined and the miners could not see without lamps. Attempts were made to use the phosphorescent glow from partly decayed fish, fish skins, and fungus, also to bring daylight clown into the workings by means of a series of • mirrors; •but these means of illumination proved to be impracticable."

Jan 1, 1955

By Ko-ichiro Ohno

It is recently recognized that the iron reduction and melting as well as the slag separation of a composite of granular iron ore and coal are completed in a very short period of about IO minutes when the composite is rapidly heated up to approximately 1673K. These phenomena are expected to be applied to a new iron-making process. The mechanism of iron ore reduction and iron-slag separation during rapid heating has not yet been revealed and the fundamental research has just started. Carburization of the reduced iron is regarded as one of the most important steps in this process. In the present work, the composite was prepared from four kinds of coal or graphite as a carbon source and electrolytic iron powder as a completely reduced iron ore. The temperature at which the liquid formation and iron carburization occurred was monitored. Direct observation of smelting reduction behavior was made by a confocal laser-scanning microscope combined with the infrared image-heating furnace to clarify the effect of molten ash on iron carburization. It was found that the meltdown temperature of composite became lower as the melting temperature of coal ash decreased. From the observed result, it was presumed that the liquid slag would act as an important media for the carbon transfer from coal to iron. The carburization mechanism during the smelting reduction was estimated as follows. When slag containing iron oxide melted down and contacted carbon, iron oxide in the slag was reduced and the formation of the metallic iron particle as well as the its carburization occurred simultaneously at the slag-carbon interface. Carburized iron particle was carried from slag- carbon to slag-iron interfaces due to the slag convection flow caused by the difference of the interfacial tension between the carbon-slag and iron-slag interfaces. Carburization of reduced iron could proceed with a repeat of the above-mentioned process.

Jan 1, 2003

By Ko-ichiro Ohno

It is recently recognized that the iron reduction and melting as well as the slag separation of a composite of granular iron ore and coal are completed in a very short period of about 10 minutes when the composite is rapidly heated up to approximately 1673K. These phenomena are expected to be applied to a new iron-making process. The mechanism of iron ore reduction and iron-slag separation during rapid heating has not yet been revealed and the fundamental research has just started. Carburization of the reduced iron is regarded as one of the most important steps in this process. In the present work, the composite was prepared from four kinds of coal or graphite as a carbon source and electrolytic iron powder as a completely reduced iron ore. The temperature at which the liquid formation and iron carburization occurred was monitored. Direct observation of smelting reduction behavior was made by a confocal laser-scanning microscope combined with the infrared image-heating furnace to clarify the effect of molten ash on iron carburization. It was found that the meltdown temperature of composite became lower as the melting temperature of coal ash decreased. From the observed result, it was presumed that the liquid slag would act as an important media for the carbon transfer from coal to iron. The carburization mechanism during the smelting reduction was estimated as follows. When slag containing iron oxide melted down and contacted carbon, iron oxide in the slag was reduced and the formation of the metallic iron particle as well as the its carburization occurred simultaneously at the slag-carbon interface. Carburized iron particle was carried from slag-carbon to slag-iron interfaces due to the slag convection flow caused by the difference of the interfacial tension between the carbon-slag and iron-slag interfaces. Carburization of reduced iron could proceed with a repeat of the above-mentioned process.

Jan 1, 2003

By Ross D. Lawrence

"Comparable transaction analysis is the best known of the market approaches to valuation of exploration-stage mineral properties. The analysis of option and farm-in agreements can also provide useful guidance to valuators. While such approaches can be distorted by incomplete analysis, market-based methods are capable of providing consistent, credible results when carried out carefully with due consideration paid to all factors which buyers and sellers consider when dealing in the real market.RÉSUMÉRoss D. Lawrence graduated from the University of Toronto with a B.A.Sc. (Applied Geology-1956) and an M.Comm. (Mining Finance-1959). As a student and following graduation, he worked across Canada on a variety of mineral exploration projects.In 1962, he was one of the founders of Watts, Griffis and McOuat, and has practiced as consulting engineer since then. For the past 20 years, Mr. Lawrence has headed up the WGM valuation practice, responsible for a group of professionals which has carried out scores of valuations of mineral properties and mining companies. He is a Certified Minerals Appraiser of the AIMA and an active participant in professional affairs.INTRODUCTIONMineral properties without defined resources present one of the most challenging tasks to the mineral valuator. You will hear from others at this conference about the use of cost and income approaches to the problem of valuing exploration properties. This paper will concentrate on market-based approaches. Market based-approaches are based on the principle of substitution and include such techniques as:??Comparable transaction analysis (sometimes referred to as sales comparison analysis).??Farm-in commitment analysis??Rules of thumbAre there any valuation standards available to assist the valuator? In Canada there are none that apply to the valuation of mineral assets or securities. This problem is being addressed, at least in part, by the CIMVal committee of the Canadian Institute of Mining, Metallurgy & Petroleum (CIM)1. Further, the recently established Canadian Association of Mineral Valuators will be giving consideration to the adoption of valuation standards."

Jan 1, 2003

By A. P. Mehta

The role of microorganisms in the leaching of metal sulfides is well established (Torma, 1977; Murr, 1980). However, this established knowledge applies mostly to chemolithotropic microorganisms such as Thiobacillus ferrooxidans which function optimally in leaching catalysis between 25-35° C, and in a pH range of 2-2.5. Although leaching with thermophilic microorganisms capable of extending the range of catalytic viability beyond 35° C is also documented, there are few if any attempts to optimize or extend sulfide concentrate leaching with thermophilic microorganisms. When mixed metal sulfides or other materials having different rest potentials (referenced to the standard hydrogen electrode, SHE, in the electromotive series) make contact in a conducting, aqueous medium, the contacting members will act as an electrochemical cell, with the member having the higher rest potential assuming the role of an electrical cathode. In leaching reactions involving such galvanic couples, the cathode becomes passivated, while the anodic member reacts vigorously due to the electro- chemical reaction which occurs (Hiskey and Wads- worth, 1975). Serry, eta1 (1978) observed that when chalcopyrite and pyrite were in intimate contact in natural ores, the chalcopyrite reacted vigorously by galvanic conversion as a result of the higher rest potential (~ 0.63 V) as compared to the chalcopyrite (~ 0.53 V). In addition, it was postulated that because of the elemental sulfur which can form on the anodic chalcopyrite in this galvanic conversion process, reactions in acid-bacterial medium would be expected to have accelerated copper extraction because of the conversion of any sulfur product layer on the chalcopyrite anode to sulfuric acid according to the following general reactions: [MS?M2+ + S° + 2e- (1) and 2S° + 302 + 2H20 bacteria?-2H2SO 4 (2)] where M in reaction (1) designates the metal (or metals in the specific case of chalcopyrite) to be released to solution by galvanic conversion.

Jan 1, 1982

By T. L. McCall

CHANGES in mining practices have evolved so quietly and unobtrusively that perhaps we scarcely appreciate how truly startling these changes are unless we cast our minds back so as to compare the past with the present. Such retrospection is, indeed, necessary when attempting to forecast the future, for it is only by carefully reviewing the past that we can hope to obtain an indication of what the future may hold in store. In this instance, it is not necessary to delve into the very early history of . coal mining, as our purpose will be served if the last three or four decades are reviewed, a period that is still fresh within the memory of many of us. These earlier days might be termed the selective period of mining, for at that time the coal resources of the world had not been tapped to anything like the extent they are at present and this condition enabled the owners and operators to exercise selective powers and only mine such seams of coal as could be most easily reached an worked at the lowest possible cost and which, at the same time, would suit the requirements of the market. Carrying this thought of selective mining still further, the miner, who was then an artisan skilled in all the branches of his calling, was able to select or discard such parts of the seam he was working that the co al sent out of the mine was acceptable to the consumer with just the barest minimum of preparation. Compare these conditions with the? conditions prevailing today, when coal seams of medium height, good quality, and readily accessible have been largely depleted and the operator has been compelled either to carry on his operations under much greater depths of cover where the coal is more costly to win, or else to work seams of lesser height or of poorer quality.

Jan 1, 1938

By B. J. Bluck

Diamond mega-placers, in order to rank amongst the primary diamond deposits, are defined as => 70 m carats at =>95% gem quality. There is only one mega-placer known and that is found along the coast of southwestern Africa fringing the Kaapvaal craton. Placers are classified as residual when they are left on the craton, transient when being eroded into the exit drainage and terminal. Terminal placers, in being the final depositories of diamonds off the craton, have the greatest probability of being a mega-placer and such is the case in the placer deposits near the Orange River mouth, southwestern Africa. There are four main groups of conditions leading to the development of a mega-placer: the craton, the drainage, the nature of the environment at the terminus and the timing. The craton, in its role as the producer of diamonds is significant in respect to its size, diamond-fertility, the degree to which diamonds from successive kimberlite intrusions have been retained there and their availability to the final drainage yielding the mega-placer. Cratons in being buoyant have a tendency to leak diamonds into surrounding basins but in being incompressible often have orogens converge onto them resulting in lost sediment being returned as foreland basin fills. In order to concentrate a bulk of diamonds the drainage basin has to be large with a high proportion of it on the craton. The drainage yielding the mega-placer should ideally not have been preceded by older drainage and other systems that may have robbed the craton of earlier diamonds. The exits of diamonds from the craton need to be few in order to focus on their supply and the drainage network needs to be efficient in order to remove the maximum volume of diamonds off the craton. This efficiency and the focused termination is best achieved by the rejuvenation of a pre-existing drainage network. The drainage should be young enough to yield host sediments friable enough to allow brittle diamonds to be recovered from them.

Jan 1, 2004

By D. M. Ramsey

HIGH-INTENSITY magnetic separation as now practised in the commercial treatment of a large variety of industrial minerals is a com-paratively recent development, having had its practical beginning about ten years ago when it became necessary to devise more effective methods for the purification of the electric furnace abrasives and refractories-silicon carbide and fused aluminium oxide. The fundamentals of magnetic separation are, of course, very well under-stood; bur while very, very old in principle, the process has, in recent years, been developed to a point of far greater usefulness than heretofore. In fact, until the development of the high-intensity process,. magnetic separation was limited largely to the removal of tramp iron? with magnetic pulleys and the removal of the very highly magnetic portions of industrial minerals by means of horizontal conveyor-belt-type separators. All magnetic separation processes depend for their success on the fact that various materials are kinetically influenced to a greater or lesser degree by the force that we speak of as 'magnetism'. We have now come to regard 'magnetic separation' and 'high-intensity magnetic separation' as two different and distinct methods. However, both depend upon the reaction of a particle when placed in a magnetic field. The common types of magnetic separators quite generally operate on the principle that a magnetic particle can be lifted by a powerful magnetic force from a stream of material moving on a belt or other type of conveyor. The application of the force removing magnetic material by this scheme is directly opposed to the force of gravity and is, therefore, limited to sub-stances of a relatively high order of magnetic susceptibility, such as metallic iron and magnetite. Until a few years ago, one very important principle was almost entirely overlooked. Practically every substance is susceptible to some extent, at least, to magnetic attraction, and by the application of a magnetic force great enough, and properly applied, separations of materials heretofore considered 'non-magnetic' can be accomplished.

Jan 1, 1937

By George Langford

Introduction The manufacture of ductile beryllium is one of the most interesting problems confronting the metallurgist today, and one which becomes more acutely in need of resolution as the uses for beryllium increase. Beryllium belongs to the hexagonal group of metals along with zinc, magnesium, and cadmium. The melting point of the metal is about l,280°C. ± 5°C. Due to its brittleness, the metal's chief use is as an alloying agent in copper and iron. The very low absorption coefficient of beryllium for x-rays makes the metal ideal for x-ray windows, and, similarly, because of its low capture cross-section for neutrons, the metal holds a preferred position in the field of nuclear physics. Modern x-ray diffraction methods were responsible for explaining the mechanism whereby zinc metal, although brittle when cast, could be made ductile at room temperature. The diffraction patterns of zinc and magnesium indicated the importance of the parts played by recrystallization and preferred orientation in this mechanism. It was with this in mind that an Investigation into the recrystallization and preferred orientation of beryllium was undertaken. The investigation, after a series of experiments were conducted involving cold-working and annealing, yielded the recrystallization temperature curve for beryllium. Both the texture of preferred orientation and the effect of recrystallization on this texture when subjected to compressive stresses were also determined. W. A. Alexander, J. K. Swinton and L. M. Pidgeon, in their investigation on The Recrystallization Temperature of Beryllium (C.I.M., Trans., Vol. L, 1947, pp. 657-664), utilized the Brinell ball as a means of cold straining the metal. Sufficient strain was developed to estimate the recrystallization curve for the metal. However, in order to determine the lowest recrystallization curve, as well as to develop a preferred orientation structure, larger deformation than that possible with a Brinell ball was required. The plastic deformation of beryllium can be carried out at an elevated temperature above 700°C. Above 850°C., the metal is quite ductile and can be readily compressed or extruded.

Jan 1, 1948

By L. R. Burdick, J. F. Barkley

The inherent heating value or the amount of heat that will be produced when a coal is completely burned is measured in British thermal units (B. t. u.) per pound of coal . This standard heat unit is the quantity of heat required to raise the temperature of 1 pound of water 1 °F . at about 60 °F . The amount of inherent heat is determined by burning a small quantity of the coal in a heat meter or calorimeter , which gives results in British thermal units . The exact manner of making this test is standardized by the American Society for Testing Materials.4/ The value so determined is the total heat developed by complete burning, with all the products of combustion cooled down to the temperature of the calorimeter . The calorimeter is kept at about room temperature . This total heat is sometimes called the " high" or gross heat value , because it includes the latent heat given up by the water vapor in the products of combustion when the vapor condenses to water in the calorimeter . The heat as measured is reported as the heat of combustion at constant volume , since the burning is carried out in a tightly closed calorimeter chamber whose volume does not change . In actual use , coal is usually burned in an open - end chamber at constant pressure , generally somewhere near atmospheric . As the heat of combustion of coal at constant pressure is very slightly higher than the heat of combustion at constant volume , it might be considered that the heat at constant pressure should be used as the standard reference base . For an ordinary eastern coal the heat at constant pressure is about 16 B. t . u. per pound higher than the heat at constant volume . Calorimeter corrections , ordinarily not considered , that could have been subtracted from the heating value before reporting , may amount to about as much . Hence , the value reported is apt to be more nearly the true heating value at constant pressure than at constant volume .

Dec 1, 1941

By James J. Komadina, Robert R. Beebe

"Heap leaching of gold ores has enjoyed wide acceptance in the arid and semi-arid regions of the western U.S., Australia and South America. There are areas, however, where cold weather or excessive precipitation can limit the usefulness of heap leaching. Even in Nevada difficulties can be encountered which call for special operating procedures.The paper discusses the general climatological limitations and some of the techniques used to extend heap leaching into colder conditions. A case history of the Cripple Creek and Victor Gold Mining Company operation in Colorado examines 'valley-fill"" technology as an ideal cold-climate solution, where topographical conditions permit.AcknowledgementsThe authors gratefully acknowledge the management of Independence Mining Company for their permission to present this paper. The contributions of Golder Associates; Pikes Peak Mining Company Environmental Affairs Department staff, and the Colorado Department of Mines and Geology were all invaluable in successfully concluding this project.BackgroundWhen heap leaching of oxidized gold ores was introduced in the rnid-1970s it was aimed at large tonnages of low-grade material which could not, in general, be developed via conventional milling. Normally, the reasons for this were economic rather than technical: capital and operating costs for milling were simply too high. At first, grade was almost the only criterion, but deposits too small to justify milling were also potential targets for heap leaching.Renewed interest in gold was centered in the western United States and Australia, where exploration for milling-grade deposits had never really died. When heap leaching came along, it was in these areas that the first developments took place. Coincidentally, these same areas were favorable for heap leaching: climates were temperate for most of the year and competing land uses were limited. Even so, in the western United States in particular, winter temperatures were low enough to complicate operations. Precipitation was less a problem, although heavy snowfalls could periodically interfere as well."

Jan 1, 1997

By Cassandra A. Wetzel

"Rock socketed mini-piles are a desirable foundation alternative when design capacity is more than 40 tons and there is limited access. In this case history mini-piles were designed to support between 75 and 200 kips at 12 locations adjacent to a perimeter wall, a party wall and at cast iron column piers. Limited geotechnical information, low overhead clearance, and active building population tested the creativity of the team to get the piles installed. The key geotechnical concern during installation of the mini-piles was the presence of a glacial till layer above the bedrock surface that restricted the seating of the casing into bedrock with a track mounted drill rig. Soil loss during the advancement of the rock socket using an air hammer was excessive and increased the risk of subsidence. Over a three week period the engineer worked with the contractor to modify the design, means, methods, and materials to install piles with adequate load capacity. This paper will present the changes in design and construction methods that were required.INTRODUCTIONRock-socketed mini-piles are a common and desirable deep foundation alternative to support loads more than 40 tons in New York City. Limited vertical clearance, accessibility, vibration control, and load capacity make this pile type attractive; it also does not require a static axial load test when socketed into rock. This added benefit makes this alternative all the more feasible.The installation of a drilled pipe extending to bedrock through a glacial till deposit presented challenges to the contractor and engineers to confirm the casing is seated sufficiently into the rock prior to drilling the rock socket. The loss of soil between the steel pipe and the till/bedrock interface can compromise the performance of the pile and soil loss can result in settlement of the ground surface.This paper presents the design and construction method changes made on one project during the installation of ten limited access rock socketed mini-piles."

Jan 1, 2017

By R. Hurman Eric

The dew-point technique of activity measurements take advantage of the volatility of a component in solution. The pressure of the volatile component over a sample is determined from observations of the temperature at which condensation of the vapor occurs. The method is applicable best when the vapor pressure of the components would differ by about two to three orders of magnitude. Experimentally, this is a closed system involving the use of evacuated and sealed transparent quartz sample probes. Furthermore reliable vapor pressure data of the volatile component is essential along with a specialized high temperature furnace capable of giving reproducible results. In this context, the vertical Dew-Point Furnace (DPF) was designed and built after elaborate trails until enough proficiency was gained for reproducible results. Over the years the DPF was modified and improved. The DPF developed was versatile and could easily be used for activity measurements in the isopiestic mode (another method of measuring activities of a volatile component in a solution). The necessary ancillary systems; namely evacuation-flushing-evacuation followed by sealing of quartz sample probes under vacuum were also perfected over the years. As and when necessary the dew-point technique was supplemented by classical equilibration-quenching method employed on the sealed quartz sample probes to reveal necessary phase equilibrium information. The following were studied utilizing the above technique: (i) Activities in CU2S-PbS and FeS-PbS binaries and CU2S-FeS- PbS ternary at 1200°C; (ii) Activities in Cu2S-SnS and FeS-SnS binaries and Cu2S-FeS-SnS ternary at I200°C; (iii) Phase equilibria and thermodynamic in Cu-Pb-S, Fe-Pb-S, Fe-Sn-S, Cu-Sn-S and Ag-Sn-S systems. Most recently the following systems have been tackled: (i) Phase equilibria and thermodynamics in the Ag-Pb-S and Sn-Pb-S systems; and (ii) Activities in Ag2S-FeS-CuzS-PbS quaternary at 1200°C.

Jan 1, 2003

By Angus D. Campbell

"IntroductionThe subject assigned to me tonight gives unlimited scope. The material available is so voluminous and leads into so many ramifications, and the memories of the Camp are so vivid and treasured, that it is difficult to decide just what to use. Then, too, the geologists are the story-tellers of our tribe - I am only a hard rock miner.Members of the Cobalt Branch and Cobalters everywhere will agree without question that this Cobalt camp has been the greatest of all influences on Canadian mining. To those who do not know Cobalt, our opinion may seem prejudiced and our statement exaggerated.Be that as it may, discussion on this subject can be profitable, since it is worthwhile now and then to think on 'whence we came' and 'where we are going'.In the revival of interest in the Cobalt camp, we hope our guests may feel some of the old Cobalt Spirit, which has become the Spirit of the North.Visitors may even, while here, catch a glimpse of that whimsical little guardian spirit of the camp - the original goblin, the Kobold - for which Cobalt was named.While Kobold brings that good luck which plays so important a part in mining, he can have his evil moments, as in his original German home. There, when he made the silver disappear from their good ore, they cursed the grey ore, calling it Kobold.Although this little goblin bas frequently upset our best mining plans and geological calculations, be has played the game as well. He placed •some silver on the surface, and when he hid ~t at depth he left dues .for its finding. He has rewarded many who sought his treasure and is still rewarding those who have persevered and had faith in him. t:lis influence and that of Cobalt camp has probably had a greater influence on your work and your mining areas than you realize"

Jan 1, 1950

By R. Hurman Eric

The dew-point technique of activity measurements take advantage of the volatility of a component in solution. The pressure of the volatile component over a sample is determined from observations of the temperature at which condensation of the vapor occurs. The method is applicable best when the vapor pressure of the components would differ by about two to three orders of magnitude. Experimentally, this is a closed system involving the use of evacuated and sealed transparent quartz sample probes. Furthermore reliable vapor pressure data of the volatile component is essential along with a specialized high temperature furnace capable of giving reproducible results. In this context, the vertical Dew-Point Furnace (DPF) was designed and built after elaborate trails until enough proficiency was gained for reprodueible results. Over the years the DPF was modified and improved. The DPF developed was versatile and could easily be used for activity measurements in the isopiestic mode (another method of measuring activities of a volatile component in a solution). The necessary ancillary systems; namely evacuation-flushing-evacuation followed by sealing of quartz sample probes under vacuum were also perfected over the years. As and when necessary the dew-point technique was supplemented by classical equilibration-quenching method employed on the sealed quartz sample probes to reveal necessary phase equilibrium information. The following were studied utilizing the above technique: (i) Activities in CuzS-PbS and FeS-PbS binaries and CU2S-FeS- PbS ternary at 1200°C; (ii) Activities in CuzS-SnS and FeS-SnS binaries and Cu2S-FeS-SnS ternary at 1200°C; (iii) Phase equilibria and thennodynamic in Cu-Pb-S, Fe-Pb-S, Fe-Sn-S, Cu-Sn-S and Ag-Sn-S systems. Most recently the following systems have been tackled: (i) Phase equilibria and thennodynamics in the Ag-Pb-S and Sn-Pb-S systems; and (ii) Activities in Ag2S-FeS-CuzS-PbS quaternary at 1200°C.

Jan 1, 2003

By R. R. Rogers

Abstract The degree of cathodic protection of steel and the anode corrosion rate were determined when anodes and waters of different compositions were used at temperatures similar to those in domestic hot water tanks. Twenty different anode materials, sixteen of them magnesium-zinc-aluminium alloys, were immersed in six different synthetic waters resembling those to be found in various parts of Canada. The results showed that (1) both the degree of cathode protection and the average anode corrosion rate are affected materially by the composition of the anode material and of the water; (2) poor cathode protection is associated with low anode corrosion rate; (3) when the cathode is fully protected, the anode corrosion rate may be comparatively low or comparatively high, depending upon the composttion of the water; (4) an important relationship exists between the magnesium content of the preferred anode and the composition of the water; (5) the degree of protection is increased as the SO4 + Cl concentration of the water is increased and thus as its specific resistance is decreased. Introduction Fairly recently, the use of the active metal magnesium for the cathodic protection of less active metals has received a considerable amount of attention. This interest has been stimulated by the fact that the wartime demand for magnesium was greatly in excess of the present peacetime demand and there is a natural desire to continue operating the large magnesium plants which were built during the war. Information regarding the use of zinc and aluminium for this purpose also has been published. There is a great demand for domestic hot-water tanks which will resist corrosion satisfactorily. This problem is rather complex in view of the fact that the composition of the water used in such tanks varies greatly and depends upon the locality. The present investigation deals with the effect of water composition and anode composition on the cathodic protection of steel under conditions approaching those which exist in hot water tanks.

Jan 1, 1948

By D Baas, J Le, R Braun, R Chandramohan, K Hollis, G Lane

The Phu Kham Copper-Gold Operation (Phu Kham) is located in northern Laos, approximately 140 kilometres from the capital, Vientiane. The operation is a producing asset for Australian-based copper and gold producer, PanAust Limited (PanAust) and is operated by Lao-registered company, Phu Bia Mining Limited (Phu Bia Mining). PanAust holds a 90 % interest in Phu Bia Mining. The Government of Laos owns the remaining 10 %.The Phu Kham Operation has recently undergone a series of process improvements to treat the anticipated competent ores scheduled for 2017 and 2018. The operation’s comminution circuit, which comprises a semi-autogenous (SAG) mill and two ball mills, each with 13 megawatts (MW) of installed power, was expected to be SAG mill limited when treating competent basement rock. Ausenco Services Pty Ltd (Ausenco), was engaged to help optimise and enhance the productivity of the Phu Kham comminution circuit over an eight-month period. The work involved participating in and overseeing the redesign of the SAG mill liner systems and developing operational strategies for maximising throughput through to the end of mine life. Ausenco’s comminution optimisation tool, Ausgrind, was used to benchmark and analyse plant data with empirical models, predict circuit performance for varying ore characteristics and evaluate liner wear and predict the life for varying operating parameters. Variances between the actual and the predicted values were assessed in detail to identify missed opportunities, and guiding operating parameters were redefined to maximise throughput and productivity. In combination with the redesigned liner system, optimised process controls for varying ore competencies, and improved operational practices and troubleshooting strategies, increased Phu Kham overall production, exceeding the milling capacity when treating competent ores. CITATION:Chandramohan, R, Braun, R, Lane, G, Hollis, K, Le, J and Baas, D, 2018. SAG mill optimisation and increasing throughput at the Phu Kham Copper-Gold Operation – a success story, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 113–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By J Safarian, D Hariswijaya

Treating bauxite residue as an alternative source of metals for iron and aluminium industry is an approach to promote circular economy in metal industries. Reduction of metal oxides with H2-based process is an important step on decarbonisation of metal industry. In this study bauxite residue pellets were prepared and were reduced with different H2-H2O gas compositions at different temperatures which yielded with various degrees of reduction. The bauxite residue pellets were made from a mixture of bauxite residue and Ca(OH)2 powders and sintered at 1150°C. Hydrogen reduction was carried out on the oxide pellets using a resistance furnace at elevated temperatures in controlled reduction atmosphere of H2-H2O gas mixtures which resulted in reduction of iron oxides in the pellets. Unreduced and reduced pellets were subsequently heated to 1400°C to study their smelting behaviour using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) technique to investigate the evolution of phases related to slag formation via smelting. Equilibrium module of Factsage™ ver 8.1 was utilised to analyse results of thermal analysis. It was observed that Tricalcium phosphate-β (CaP2O8), Bredigite (Ca7Si4MgO16), Rankinite (Ca3Si2O7), and calcium alumino ferrite (Ca[Al,Fe]6O10) were formed during thermal analysis as intermediate phases. The initial slag formation for sintered and reduced pellets occurred at 900°C which mainly contains calcium and small amount of strontium component. The slag formation rate increases significantly starting from 1100°C when iron oxides started to form initial molten slag phase which then followed by other oxides dissolution in the system. Gas formation was observed at 1180°C and it was found that the gas to be released from unreduced pellets is O2 meanwhile the gas to be released from reduced pellets is SO2 gas. Gas formation rate for both pellets start to increase at 1280°C when the remaining chemically bonded gas start to be released from the system.

Jun 19, 2024

By E J. B van Etten

Pit lakes may form when open cut mining leaves a pit void that then fills with ground and surface waters. This often replaces terrestrial ecosystems that existed prior to mining with an aquatic ecosystem, affording an opportunity to improve regional aquatic biodiversity values through targeted aquatic restoration (McCullough and van Etten, 2011). Restoration theory provides guidance when restoring disturbed systems towards landscapes that are of regional value and relevance. But how do we identify a restoration target for a novel aquatic habitat that only exists in the new post-mining landscape? This paper presents a process of first identifying and then surveying local representative aquatic systems, to provide a direction for pit lake restoration efforts and achievement criteria for pit lake relinquishment, using a case study from a sand mining operation amongst wetlands in south-western Australia.The company mines silica sands following mechanical removal of topsoil and then extraction of the ore from below the watertable by dredging. Assessment of wetland and riparian vegetation was achieved through the establishment and measurement of temporary monitoring transects across five natural wetlands in the Kemerton area. Several more regional wetlands were also visited and observations made to supplement and validate these data.Distinct vegetation zonation was found across each wetland, although typically wetland basins were unvegetated or filled with younger woody plants with patchy distributions. Fringing riparian vegetation consisted of few species (commonly the paperbark Melaleuca rhaphiophylla and the sedge Lepidosperma longitudinale), but community composition and structure were variable between wetlands. The pattern of vegetation seen across natural wetlands was best explained by topography and soil chemistry, with low lying wetland areas more likely to experience regular flooding and accumulate organic matter and nutrients.In conclusion, where they are available, regional natural waterbodies may constitute the best valid restoration goal. Nevertheless, the goal may need to consist of a range of closure design opportunities, rather than a single target.

Oct 5, 2011