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By Marie-Eve Boucher

The slag in iron ore pellets allows wet sintering during firing and leads to suitable bounding. The process of slag formation differs whether it takes place in the core or in the external zone of a pellet. In the core, hematite can be reduced to secondary hematite, depending on the temperature and on the carbon monoxide/dioxide partial pressure ratio. The reaction rim that appears at the outskirts of a silica particle in contact with the FeO bearing magnetite is considered as the slag precursor in the core of the pellet. By contrast, in the external zone of a pellet, where O2 is available and CO partial pressure is very low, the first step towards slag formation is flux decomposition, mainly dolomite and limestone. The CaO liberated through this reaction will be available to react with hematite by solid diffusion to form calcioferrites, which play an active part in the slag evolution process. These two slag formation paths will be explained.

May 1, 2007

By K. Howard Poulsen

Shear zones are tabular tructures which tend to occur either discordantly within, or concordantly along the margins of, competent rock masse uch as plutons, sill or flows. They contain deformed equivalents of their host rock and are common sites for gold mineralization localized in tructure oriented y tematically relative to the shear zones and internal linear fabric. Apan from genetic implications, hear zone analysis proves useful in exploration for this type of deposit because the zones are generally wider and more continuous than associated mineralization and because there is an element of predictability to mineralization geometry (i.e. vein orientation. plunge).

Jan 1, 1986

By S. C. Tadolini, J. M. Goris, J. L. Gallagher

Cable supports offer several advantages over traditional secondary support methods by enhancing stress redistribution to pillars and gob areas, minimizing or eliminating timbers and cribs that reduce ventilation, eradicating material-handling injuries related to placement of crib supports, and providing a cost-effective alternative to secondary support. The U.S. Bureau of Mines (USBM), researching alternatives to traditional roof support methods, designed and installed high-strength cable supports to improve the stability of longwall gate road entries in a western U.S. coal mine. With the cooperation of industry, methods were developed to install and evaluate cable supports in a tailgate area using traditional resin cartridges. The cable-bolted areas successfully maintained roof support throughout the developed entries. Cable supports have replaced wood cribbing as secondary support in the bleeder entry system and have minimized or eliminated the use of cribbing in the longwall tailgate entries. This paper describes the theory, application, and advantages of cable supports and presents some mine measurements made to assess the cable performance during the retreat process of longwall mining.

Jan 1, 1999

By Harold N. Miller

Lost time and services caused by electrical equipment breakdown or cable faults can often be substantially reduced by the use of direct-current high-voltage testing as a maintenance tool. This paper discusses the relative merits of alternating-current versus direct-current testing, pointing out the advantages in size and cost of equipment and more definitive results achieved through the use of D.C. General principles of direct-current high-volt-age testing, types of testing, methods of performing the actual test and interpreting the results are explained. ?The value of insulation resistance measurements and their relationship to high-voltage testing is discussed. Pinpointing the physical location of a cable defect using a fault locator or thumper is described. Reference is made to several organizations that have effected considerable savings with high-voltage test programs. Introduction T HE past decades have seen great advances in the field of electrical power distribution and application. Motor generators, power-operated equipment, cables, etc., have all gone through various stages of improvement both in efficiency and reliability. Un-fortunately, however, power failures and equipment breakdown still occur -frequently with disastrous effects in loss of time,

Jan 1, 1965

By H. Arima

The Akita Zinc Company is the only refinery which produces hematite from the iron content in the zinc leach residue. The Akita Hematite Process consists of five stages, which are SO2 pressure leaching, the first neutralization stage, the de-arsenic process, the second neutralization stage and pressure hematite precipitation. In order to strengthen its cost competitiveness and stabilize its operation, the Akita Hematite Process has been modified continuously. Most recently, two process modifications were carried out. The first was an improved ability to maintain a lower arsenic concentration in the de-arsenic process, and the second was an increased throughput in the hematite precipitation autoclave. The details of these recent changes in the Akita Hematite Process are presented in this paper.

Jan 1, 2006

By J. F. Henderson

Stable mining operations commenced in the Northwest Territories in 1933. Pitchblende from Great Bear lake and gold from the Yellowknife district are the main minerals produced. The value of pitchblende products produced from 1933 to 1941 was nearly $6; 000; 000; data on subsequent production are not available. The first gold was produced from the Con mine at Yellowknife in 1938. Other properties that later came into production include the Negus; Slave Lake; Thompson Lundmark; and Ptarmigan mines. The annual gold production reached $3; 862; 000 in 1942 but due to the war and consequent labour shortage fell to $333; 218 in 1945. The only producing mines at present (May; 1947) are the Con and Negus; but several promising properties are under development; including that of Giant Yellowknife Gold Mines where large tonnages of ore are being blocked out. With the reopening of former producing mines and new production from properties now being developed; gold production should rapidly increase and exceed its former peak within the next few years.

Jan 1, 1954

By Howard W. Tipper, Richard B. Campbell

"The Quesnel Trough is underlain by a thick sequence of mainly Upper Triassic and Lower Jurassic volcanic-clastic and sedimentary rocks that lie between the highly deformed Proterozoic and Paleozoic rocks in the Omineca Geanticline to the east and the Upper Paleozoic Cache Creek Group in the Pinchi Geanticline to the west. Broad areas of the Trough between Kamloops and Williams Lake are covered by Eocene volcanics and sediments and by Miocene-Pliocene plateau lava. Granitic intrusions were apparently mainly confined to two major episodes; one about 200 m.y. ago (coeval with the Guichon batholith) and one about 100 m.y. ago. In addition, the region includes small granitic and syenitic intrusions, some porphyritic, that may be all or partly still younger. Exposures in the region are generally small and scattered, obscured by widespread, not necessarily thick glacial deposits. This, together with the extensive Tertiary cover, makes prospecting difficult. The part of the Quesnel Trough discussed here is the direct northwest-ward extension of the copper-rich Kamloops-Merritt-Princeton region. It contains the Boss Mountain molybdenum mine, related to a breccia zone induced in a batholith of the oldest group by a younger intrusion, and the Cariboo Bell copper deposit in Lower Jurassic volcanic-elastic rocks and syenitic intrusions. The Gibraltar deposit, in a 200-m.y. intrusion, is within the Pinchi Geanticline close to the margin of the Trough. Molybdenum prospects are mainly restricted within or near the 100-m.y. granitic rocks. Copper prospects, on the other hand, are most prominent in the volcanic-elastic rocks and in the 200-m.y.-old granitic rocks, although they can also be spatially related to younger intrusions. Copper thus has a wide potential distribution.The writers believe that the region is deserving of careful and comprehensive exploration by directly applying the knowledge and techniques developed in the important producing areas to the south. All of the major pre-Tertiary geological elements seem to have potential for mineral deposits; none should be ignored. A thorough knowledge of the thickness and distribution of the Tertiary rocks and the development of geophysical methods to ""see through"" them is of particular importance."

Jan 1, 1970

By A. P. Schissler

Mining has several characteristics, uncommon in other business sectors, which pose additional challenges to the implementation or design of IT and management systems that use the information. Understanding these characteristics would improve the chances of successfully importing new information technology and management techniques to mineral producers. The most important characteristics that should be understood are workplace issues, the industry’s dual nature of being a continuous construction project using cyclical factory processes, labour challenges, workplace culture, information availability, integrative data elements, and the current technical education of mining engineers. These characteristics were taken into account in two applications of information technology and systems design at operating companies. The research and consulting projects focused on the development of an IT-enabled performance management system at several underground metal mines in Canada and an integrated data warehouse for surface mines spread throughout the United States and Latin America.

Jan 1, 2006

By H. Abdollahi

Cold rolling is one of the most important techniques in metal forming since the cold rolling products are almost finished product, The product quality of this process is widely influenced by friction in the roll gap; therefore, controlling the friction and other parameters affecting the cold rolling is very important in order to have a product with high quality, Among the cold rolling parameters, the pressure distribution or friction hill within the roll gap is known as the most significant one, In this study, a new software (Matroll), is introduced which can determine the coefficient of friction (COF) and plot the friction hills for an industrial mill, Besides, based on rolling equations, it offers about 25 rolling parameters as outputs. To verify the software operation, the real industrial rolling data was used as inputs, The results (outputs) are in good agreements with the findings of other researchers, The COF values are very reasonable, The friction hill shows that COF is not constant over the whole arc of contact.

Jan 1, 2005

By J B. Magee

Sheep Creek Mines Limited has developed several operating techniques that have greatly assisted in keeping unit costs at reasonable levels. Some of the techniques, as described in this paper, include organization, accounting, warehousing, bonus and contracts. INTRODUCTION THIS paper is a non-technical report on operating techniques developed by Sheep Creek Mines Limited at their Mineral King mine, located near lnvermere, B.C. Depressed metal prices and continually rising labour and materials costs have necessitated a continuous search for method to keep operating costs down. The newly developed techniques and practices have greatly assisted in maintaining unit costs. Sheep Creek Mines Limited is a mining company incorporated under the laws of the Province of British Columbia. The Company's share capital is 3,500,000 common shares, witl1 a par value of 50 cents each, of which there are 1,875 000 shares is-sued. The Company has eight di-rectors. The administration, exploration and accounting offices are located in Nelson, B.C. The Company's working capital is approximately $1,500,000.

Jan 1, 1963

By S. P. Singh

"The geological features of a rock mass have a direct influence on its blasting characteristics. It has been observed that perimeter control techniques provide excellent results in massive crystalline formations but may give poor results in weak and or highly jointed formations.A field study was conducted with the objective of understanding the role played by the geological features of a rock mass in producing and controlling blast damage. The field work involved the assessment of blast damage at several operating mines and the blasting of drift rounds in a geologically dominant rock mass.The effect of rock strength, rock quality designation (RQD), joint parameters and hydrogeological conditions on blast damage is described below. The influence of number and thickness of weak layers on blast damage is also discussed below on the basis of quantitative data. In addition, critical particle velocity ranges for damage to different rock types have also been outlined in this paper."

Jan 1, 2001

By Erwin L. Zodrow

"IntroductionThrough an extensive coal sampling project in the Sydney coalfield of Nova Scotia during 1981 - 1984 involving a majority of the mineable coals (Zodrow, 1985, Fig. 1), a sizeable inventory on trace, minor and major metals was established. In this paper, results of studying the inventory are summarized, concentrating mainly on the relationship that exists between metal variations and thickness of coal channel samples (i.e. trends) and on explaining the trends in geochemical and sedimentological terms. As an over-all conclusion the Everglades peat of Florida is proposed as a modern-day analogue to Upper Carboniferous peat swamp development that took place in the Sydney Basin.Data InventoryFor this study 17 channel samples were cut , 8 cm to 14 cm channel width and 8 cm to 10 cm depth, from 10 successive coals which in stratigraphically descending order are as follows: Point Aconi (3), overrider Lloyd Cove (2), Lloyd Cove (2), Stubbart (2), Harbour (4), Backpit (I), Phalen (,I), Shoemaker (1) and McAulay (I), where bracketed values signify the number of channel samples cut from a seam (Zodrow, 1985, Fig. I). Each channel sample was subdivided by 15 em incremental length yielding a total sample size of 137 for analysis. By appropriate modern techniques these samples were analyzed to determine concentration levels for 32 chemical elements and ash content, the average results of which are presented in Table 1.Tests were also made for Pd, Pt, Ga, Nb, Cd, Cs, Sm and W but their concentration levels in many instances hovered on the lower detection limits that were used and on this accounts are excluded from discussion. Ashing, when necessary for the determination of concentration levels, was done for 12 hours at a temperature not exceeding 450°C. Concentration levels for the elements are reported in reference to whole-coal or whole-coal equivalents and discussed on this basis. In the course of the analyses, lower detection limits received careful attention."

Jan 1, 1986

By James H. Cobbs

Blind boring of shafts is becoming an increasingly important part of shaft sinking. Blind-bored shafts have reached diameters of 25 It in Europe and 16-1/2 ft in the United States. Much of the technology developed for blind boring has evolved from the technology of drilling wells for oil and gas production. Blind boring offers economic advantage in a number of situations where conventional shaft sinking either is extremely difficult or very expensive by virtue of large-capacity aquifers which must be penetrated, unstable ground or where very rapid sinking is required. In sedimentary rocks, blind boring is cost competitive with conventional sinking, in diameters of about 12 ft or less. Blind boring is not competitive with raise boring where conditions are favourable for raise boring. Blind boring does, however, offer greater flexibility than raise boring and can be performed in situations where raise boring is inefficient or impossible. Combination machinery has been developed to perform both blind boring and raise boring, so that the machine can be used effectively in situations where only the near-surface portions of the shaft are unfavourable for raise boring. Development work is being supported by the United States Bureau of Mines for blind boring equipment capable of boring shafts up to 30 feet in diameter.

Jan 1, 1979

By D. Yuan, L. Yan, M. J. Collins, P. Kalanchey, I. M. Masters

ABSTRACT Pressure oxidation tests have been conducted by Sherritt for a refractory gold-silver project in China. The feed contained 39 g/t Au and 970 g/t Ag; the major gold-bearing minerals were pyrite and arsenopyrite. Because the feed contained a significant amount of silver, which can be refractory to cyanide leaching after pressure oxidation due to the formation of argentojarosite, the test program included investigation of methods to enhance silver recovery. The “lime boil” process proved successful and was incorporated into the flowsheet. Gold extraction from the lime boil product solids was 95–98%; silver extraction was up to 94%.

Jan 1, 2013

By Lise-Aurore Lapalme

Structure of the Presentation ? sustainable development and its social dimension ? challenges that mining is facing ? responses by industry ? corporate social responsibility ? the role of government Sustainable Development ? new perspective on how we view development ? consider how minerals and metals contributes to sustainable development ? challenge to better understand economic, environmental and social aspects ? make social aspects more broadly understood and appreciated

May 1, 2002

By W. Dziurzynski, St. Wasilewski, T. Palka, A. Krach

"Air parameter monitoring systems, regardless of gasometrical protections, provide a significant number of measurement data. The obtained data broadens the knowledge on processes taking place in underground workings and shows the relationships and influence of machines and technological processes on the variability of ventilation parameters in the areas of longwalls. Nowadays, computer simulation methods are increasingly used to reproduce the flow of air and methane mixture in the area of longwalls equipped with shearers. The paper presents the results of a research experiment covering a long-term observation of a longwall area during mining with a shearer using sensors from the mine's monitoring system. Data from sensors for methane concentration, pressure and velocity were used and additional ventilation measurements were taken to determine the parameters characterising the air flow in the area. The influence of different machine cycles in the longwall on the changes of air parameters in the area of the longwall was shown. A numerical model of the ventilation area was developed and the computer program VentZroby was used for the calculations, which allows for the simulation of the process of ventilating the area of the active longwall during the extraction of coal with the use of a shearer and haulage of the run-of-mine. Computer simulation of the influence of the shearer's operation and the methane inflow associated with the distribution of the mixture of air and methane was carried out. The results of the simulation were compared with the data recorded by the monitoring system’s sensors during the measurement experiment. Comparison of the recorded methane concentration courses with the results of a computer simulation of the air and methane flow conditions in the mining area showed changes in the gassiness. INTRODUCTION Studies carried out in the Polish and global mining industry show that methane is an obvious factor in limiting mining production due to the loss of continuity in the operation of longwall complexes in hard coal mines under methane emission hazard (Schatzel et al., 2008). In addition, methane hazards have a significant impact on the safety of the operators of machinery in the longwall. The requirements of Polish regulations and the practice of safe operation of mining longwalls require correct determination of gas concentration, volume flow, as well as pressure and temperature of the flowing air. As part of the research undertaken in the Budryk (Wasilewski, 2010) and Bielszowice (Dziurzynski et al., 2009) mines to assess the methane hazard in the longwalls and workings in the vicinity of the longwall, research experiments were carried out, during which air parameters were recorded by the mine monitoring system and additional testing equipment in different cycles of shearer operation."

Jan 1, 2019

By E. L. Bruce

Introduction The Outokumpu copper mine is situated in eastern Finland, 50 kilometers west of the city of Joensuu or 225 kilometers directly north of the city of Viborg (Viipuri), which is situated at the eastern end of the gulf of Finland (Figure 1). The ore-body was discovered in 1910 by Dr. Otto Trüstedt after two years of careful, scientifically-directed, search. During the early period of development of the mine, the ore was treated locally and the copper re-covered by an electrolytic process. Now the ore is concentrated by tables and by flotation. The concentrates are shipped to Germany for refining. In 1929 the mine produced 150,000 tons of ore from which between 20,000 and 25,000 tons of flotation concentrates containing 20 per cent copper were produced. Profits in 1929 were approximately half a million dollars, but the present price of copper will affect very seriously the profits for 1930. The ore reserves are given as between 7 and 8 million tons (1). The grade of ore is stated to be 4 percent to 6 percent copper, with a little zinc.

Jan 1, 1931

By C. Jay Hodgson, P. J. MacGeehan, T. Sanders

"The orebodies of the Campbell and Dickenson mines are localized within an anomalously fissile and deformed zone that transects the eastern margin of a dominantly mafic volcanic complex close to its contact with a synchronously formed sedimentary basin containing clastic and chemical sedimentary rocks. The ore zones are mainly quartz-carbonate fissure veins and siliceous replacement zones formed during deformation and metamorphism, although there are some syn-volcanic exhalative ore zones in the mines. On a regional scale, the volcanic rocks have been affected by syn-volcanic spilitic alteration which has involved the leaching of Fe, Mg, Au and As from, and the addition of Na and variable amounts of Si to bleached zones enveloping primary permeable structures in the rocks. The leached constituents were deposited on the contemporaneous sea floor as iron-rich chemical sedimentary rocks. Although this alteration is not closely related, spatially, to the ore zones, it is characteristic of the general environment, and may serve to distinguish gold-prospective from gold-barren areas on a mining-camp scale.Closely associated spatially with gold deposits is a zone of feldspar-destructive alteration within which the volcanic rocks are characteristically feldspar-free, enriched in As, Au and to a variable degree in Si, and depleted in Na, Ca and to a variable degree in Mg, Fe and K. The alteration zone is also characterized by abundant, variably transposed, small quartz-dolomite to ferrodolomite veinlets formed during deformation and metamorphism, and includes, but extends outside of, the anomalously fissile zone hosting the orebodies. The alteration zone is interpreted to have formed syn-volcanically within the upper part of a major submarine hydrothermal discharge zone."

Jan 1, 1982

By S. Castro, L. Gutiérrez, L. Uribe

"Use of lime in seawater as a pyrite depressant decreases Mo recovery in flotation of Cu- Mo sulfide ores. When technology that uses sodium metabisulfite (MBS) to depress pyrite is applied, the process is carried out at pH 6.5–7.5, the range where Mo recovery is higher than the usual pH 11.0–12.0 when lime is applied. Redox conditions and chemical reactions involved in depression mechanisms of pyrite by MBS, or sodium sulfite, in seawater are investigated and discussed based on the acidifying effect of MBS, oxidation of sulfite ions by dissolved oxygen, and the role of catalyst of some metal cations (e.g., copper ions) adsorbed on pyrite’s surface.RÉSUMÉ L’utilisation de chaux dans de l’eau de mer comme agent déprimant de la pyrite réduit la récupération de molybdène (Mo) dans la flottation de minerais sulfurés de Cu-Mo. Lorsque l’on applique la technologie utilisant du métabisulfite (MBS) de sodium comme agent déprimant de la pyrite, le procédé se fait à un pH de 6,5 à 7,5, gamme dans laquelle la récupération de Mo est supérieure au procédé habituel utilisant un pH de 11,0 à 12,0 lorsque l’on applique de la chaux. Les conditions de réduction-oxydation (redox) et les réactions chimiques impliquées dans les mécanismes de dépression de la pyrite par le MBS (ou sulfite de sodium) dans de l’eau de mer sont étudiées et débattues sur la base de l’effet acidifiant du MBS, de l’oxydation des ions sulfites par de l’oxygène dissous et du rôle de catalyseur de certains cations métalliques (par exemple les ions de cuivre) adsorbés à la surface de la pyrite. INTRODUCTIONThe copper industry is aware of the difficulties of floating Cu-Mo sulfide ores in seawater. Molybdenum recovery is partially depressed when lime is used to reject pyrite. In plant practice, sodium metabisulfite (MBS) has been demonstrated to be the most promising option for replacing lime in seawater."

Jan 1, 2017

Orebodies of the Renison Bell - Mt. Bischoff tinfield in Tasmania are stratabound, conformable lenses of massive cassiterite-bearing pyrrhotite, with underlying discordant, fault-fracture-controlled and more siliceous ore. The deposits occur in eugeosynclinal, trough-deposited sedimentary and mafic volcanic rocks which are stratigraphically equivalent to diff erentiated volcanic rocks that contain volcanogenic massive base metal sulphide deposits in a parallel arc to the east. Textures of the massive pyrrhotite ore suggest that it has undergone metamorphic recrystallization. Although the massive ore contains both monoclinic and hexagonal pyrrhotite, a study of a few samples from one orebody suggests that their distribution is stratigraphically controlled, with the monoclinic variety abundant only at the base. The distribution pattern of rare-earth elements in massive ore is similar to that of volcanogenic massive base metal sulphides in New Brunswick, and suggests that mixing of sea water with exhalative hydrothermal brines occurred during ore deposition. Tin is a common accessory element in many volcanogenic massive base metal sulphide deposits providing strong evidence that it, too, is transported and deposited by volcanic affiliated hydrothermal brines. Sedimentary rocks containing the massive orebodies are fine grained, thinly laminated, compositionally banded and of mixed chemical sedimentary-tuffaceous origin. They include finely recrystallized chert, carbonate-rich and pyritic varieties; and soft sediment deformation structures in these rocks suggest that dense sulphides deformed underlying, less dense chert prior to lithification. Close to ore the chert becomes massive and coarsely recrystallized, as does the carbonate, which is here strongly enriched in Fe and Mn. Apatite is present in pyritic, cherty and carbonate-rich beds and in the ore itself, in all of which it shows a similar pattern of rare-earth element distribution, suggesting that it is of marine sedimentary origin. These deposits have traditionally been considered as epigenetic replacements of favourable carbonate horizons by hydro thermal flu ids derived from later Devonian porphyritic intrusions. Some of these intrusions have associated tinbearing greisens. The above relationships suggest, alternatively, that, like massive base metal sulphides, the tin deposits were of original syn-sedimentary origin. Circulating hydrothermal brines generated during early Cambrian eugeosynclinal subsidence and tectonism rose through steep fault-fractures, there giving rise to the discordant orebodies, and were discharged on the sea floor, where the massive pyrrhotite lenses were precipitated with the associated cherts and carbonates. In some places, Devonian intrusions remobilized the earlier deposits, forming greisens and newepigenetic veins. Finally , the geologic selling of these deposits, in trough deposited sedimentary and mafic volcanic rocks, suggests another favourable environment for massive sulphide exploration which is quite different from the domal felsic volcanic environment so heavily favoured currently in North America

Jan 1, 1979