Search Documents

By Rodnei Graça, Jorge Silva Bettencourt, Lena Virgínia Soares Monteiro, Baruch Spiro, Tolentino Flávio De Oliveira

Abstract - The Vazante Mine is located in the Vazante District, the largest zinc district in Brazil. The Vazante deposit consists dominantly of an unusual willemitic ore. Small sulfide bodies are tectonically imbricated with the willemitic ore, within the Vazante shear zone. Structural styles of deformation and petrographic and isotopic evidence indicate that willemitic mineralization and deformation occurred synchronously during the Neo-Proterozoic. Various generations of hydrothermal veins and hydraulic breccias may pre-date, accompany and overprint the mineralization. Ore-formation temperatures are deduced from stable isotope geothermometry and mineral chemistry of both sulfide bodies and willemitic ore. Temperatures during the main stage of mineralization range from 206°C to 294°C (willemitic ore) and 317°C (sulfides), and reflect the prevailing metamorphic conditions within the shear zone. The fluid from which the gangue minerals of the sulfide bodies precipitated (at 250°C) had an oxygen isotopic average value of ?18O = +19.4‰. This value appears to reflect the interaction of metamorphic fluid with the carbonate rocks of the Vazante formation. At 250°C, the fluid in equilibrium with the vein mineral phases and willemitic ore assemblage exhibits a uniform oxygen isotopic composition, with an average value of ?18O = +11.5‰. The positive linear covariance of ?18O and ?13C ratios of the carbonates is most likely due to the mixing of metamorphic and meteoric fluids. The ?34S values of sulfides indicate a direct crustal origin for the sulfur. It is suggested that the sulfur is largely derived from pre-existing sulfide bodies and has been transported by metamorphic fluids. The willemitic ore may have originated from the precipitation of metal in sulfur- poor fluids under oxidized conditions, within the Vazante shear zone.

Jan 1, 1999

By S. P. Jekielek

"This paper describes the automation of a mine hoist ore loading pocket using a programmable controller. It provides an introduction to programmable control, and outlines the various modes and operating sequences of the loading pocket. A comparison is made with previous equipment to illustrate the increased flexibility, reliability and diagnostic functions that are gained.IntroductionLoading pockets have evolved from a couple of manually operated air cylinders to entirely automated systems. Early pockets were usually formed in rock, with loading and discharging regulated by air-operated gate s. Interlocks, added to this arrangement, prevented simultaneous operation of the gates and ensured proper hoist position . As the loading pocket advanced, it was recognized that gravity feed posed problems, often becoming plugged or letting water run through into the shaft. A belt conveyor was employed, eliminating the se problems and resulting in greater loading control. Weighing the combination of transistorized logic modules, replaced many relay systems. This elimination of moving parts and contacts increased reliability and reduced maintenance costs.As semiconductor technology progressed, there were major breakthroughs in miniaturization and reliability, and as a result the programmable controller was introduced. Programmable controllers first appeared in the automotive industry in the late 1960's. A system controller was required to replace the large relay panels in operation at that time. The use of digital integrated circuitry enabled these programmable controllers to automate processes with hundreds of inputs and outputs. Advances in electronics reduced production costs , making controllers for smaller application s viable . This development is on-going, each generation introducing controllers with greater capabilities for a wider variety of systems. equipment was the next step in loading pocket development, and dependance on much of the manual control was reduced . The complete system was first automated using relay panels. Solid- state devices were later introduced, and static control,"

Jan 1, 1980

By Robert B. Parsons

"Canadian income tax legislation contains a number of provisions which serve to facilitate the structuring of business arrangements, including mineral resource ventures. These rules are often fairly complex and not easily understood. This article attempts to explain in plain and understandable language the mechanics and benefits of one of the more frequently encountered provisions, the ""Section 85 election"".IntroductionThe Canadian resource industries are probably singled out for more special attention under this country's tax legislation than any other industry. This special treatment is, of course, not always welcomed by the industry, such as where unnecessarily restrictive taxation is perceived to exist or where agonizingly complex tax legislation must be dealt with. On the other hand, certain provisions in the tax legislation treat the industry in a relatively favourable manner, including a number of rules which, in recognition of the high risk and capital requirements of the resource sector, serve to facilitate the structuring of resource ventures."

Jan 1, 1984

By Marcel Allard

On January 1st, 1977, SIDBEC-NORMINES INC. purchased from Quebec Cartier Mining Company various facilities located at Gagnon and Lac Jeannine together with the Fire Lake deposit. A t the same time, SIDBEC-NORMINES started its mining operations at Fire Lake, 83 km northeast of Gagnon. The paper summarizes the various adjustments which were necessary to satisfy the new production conditions, such as the physical and mechanical properties of the ore at Fire Lake, and the new crushing and loading installations at the mine, together with the transport of some 14 million tons of crude ore to the Lac Jeannine concentrator about 100km away, and finally to achieve satisfactory recovery from the FireLake ore. In addition, mention is made of the manpower organization, in which Quebec Cartier Mining Company plays an important role as manager of operations and owner of the railroad linking the mining operations to the pelletizing operations at Port-Cartier.

Jan 1, 1979

By J. C. O'Rourke

"Gibraltar Mines Ltd. has been operating its open pit copper mine for fifteen years. In that time, over 140 million tons of waste and low-grade material has been placed on the mine waste dumps. Laboratory and in situ testing indicated that enough leachable copper was recoverable from the dumps to justify a leaching operation which would include the construction of a solvent extraction-electro winning plant. The plant, which was commissioned in October 1986, was designed to process 3000 USGPM of dilute copper solution to produce 5000 tons per year of high-quality cathode copper.This paper deals with the start-up and initial year of operation of this plant. The three areas: leaching, solvent extraction, and electrowinning are presented with emphasis on the innovations which were made to help overcome the problems unique to the Gibraltar operation.The Leaching CircuitThe mine waste dumps are leached to produce a pregnant copper solution as feed to the SX-EW plant. To achieve this the dumps are sprinkled with a mildly acidic solution which percolates through the dumps. In travelling through the dumps the solution contacts the surfaces of the liberated copper minerals and dissolves the soluble copper into the form of copper sulphate. The leaching reaction is achieved by a combination of bacterial action to oxidize the sulphides and solubilization of the copper into the acid solution.For the bacterial action to occur the dumps must be near the ideal pH of 1.9 to 2.1 and the necessary elements of the reaction must be present. Because a bacterial reaction is involved there is a lag time between the time when the conditions for bacterial growth are achieved and when the bacteria are in their active growth phase. Laboratory leaching tests with Gibraltar ore indicated that bacterial action takes two to three months to reach its maximum rate (Fig. I).The expected lag time for the planned rate of bacterial leaching prompted Gibraltar to start irrigating the dumps in late June 1986 for a plant start in early fall. The lag time proved to be longer than expected and the dumps took until November to start producing copper at the expected rate (Fig. 2)."

Jan 1, 1988

By J. H. Shillabeer

"Rational exploration requires the prior selection of areas possessing excellent geological potential and minimum hazards to commercial development . Within an over-all strategy of grass-roots exploration, two procedures for selecting areas for (i) coal and (ii) metals exploration are described. The procedures explicitly balance infrastructure requirements and environmental concerns for areas of geological merit not alienated in parks and reserves. Through consensus, priorities are attached to those areas meriting closer scrutiny and field reconnaissance.IntroductionMining companies need to know that having made a potentially economic discovery, they will be allowed to develop it with minimum delay and at reasonable cost. The environment for exploration in British Columbia is complex and recent experience suggests that conditions are not becoming any easier. Conflicts over land use issues, preservation and economic development are common. The high cost of exploration requires that the risks should be offset where possible by: (i) carefully selecting the areas in which to work (ii) conducting operations in a responsible manner, and (iii) working cooperatively with the community of interests. This paper concerns the first action: prior selection of areas.To aid exploration planning at Suncor, a procedure was developed to grade those areas of the province possessing favourable geology according to the ease with which a mine might be developed . This had to be done within the constraints of the company's over-all approach to exploration. This emphasizes ""grass-roots"" exploration of self-generated projects in British Columbia. In addition, having selected a favourable belt of rocks, it is intended to persevere there while steadily adding to the accumulated data base and local experience. Hence, it is intended to concentrate on an area. This implies a long-term commitment to an area which in turn increases the importance of the original selection.Suncor's search is directed to finding base and precious metals in intrusive and volcanic environments, and export quality coal."

Jan 1, 1985

By G. Swan

"The selection of material comprising a backfill is, of economic necessity, site dependent. Nevertheless, given the existing range of typical components-coarse waste, alluvial sand, tailings a balanced or optimal choice is no straightforward matter. A new design approach toward deciding what constitutes an optimum combination of backfill material promises to be useful. In particular a 'binder ' number, based on the mean distance between aggregate particles, specific surface and cement content, is proposed. Using this number, related empirically to compressive strength, the expected mechanical performance of any cemented fill can be predicted.IntroductionOver the years a considerable volume of information has accumulated on mine backfill material design. The principal aggregate component has been deslimed mill tailings, though more recently admixtures of rock waste, sand and tailings are quite common. For these materials uniaxial compressive strength and percolation rate properties are known to be controlled by, among other things, aggregate grading. While empirical formulae exist for relating grading to percolation rates, considerable uncertainty exists concerning strength development."

Jan 1, 1985

By H. Tudeshki

A great amount of aggregate is utilized in civil engineering applications such as road construction, railway infrastructure, concrete production, etc. Igneous rocks are the preferred raw material due to their high strength and abrasion resistance. Rock quality assurance is a key factor and has great influence on the quality of constructions in civil engineering. One of the major problems encountered by both the producers and users of igneous aggregate rock is the fact that, with the passage of time, some specific rocks lose their strength, up to a complete loss of structure, i.e. disintegrate and degrade. This phenomenon has a great influence on the quality, strength and durability of aggregates. In the last decades, different methods and procedures such as the glycol test, the methylene blue dye test, as well as the Los Angeles test, have been introduced to distinguish rock properties, and to identify these problems. However, as these wet-chemical methods are time consuming, hard to perform, only to be applied to hand-piece samples, requiring special laboratory equipments, and are only possible to be accomplished under laboratory conditions, their application has always been severely limited. To address this widespread quality management problem of the quarry industry, a relatively quick, easy and user-friendly approach is necessary. It calls for a systematic solution with a device that can simply be used in the day-to-day routine of a mine for quality control of the quarry´s daily production. Our research is concentrated on developing a systematic method for early recognition and diagnosis of rock quality, in order to control and manage the quality of the quarry production in advance. Our new approach is based on two rock parameters: magnetic susceptibility and loss on ignition. The measurement of these parameters provides reliable information on the quality of the rock and allows the quality control process to be accomplished and performed at the borehole location. Our new approach has been assessed through extensive field and laboratory studies and has been implemented on the drill-cuttings of a basaltic andesite quarry. The results of the experiments are discussed in detail, including their impact on increasing resources and environmental protection.

Aug 1, 2013

By Thomas S. Falk, Nils G. Lindberg

The first industrial COBO (Cold Bound) pelletizing plant began operation in May 1975 at Trollhiittan, Swede n. A technical description of the process, together with operational experience with the plant, forms the basis of this paper.

Jan 1, 1976

"Nanisivik Mines Ltd. operates a 10-M W diesel-electric generating plant at its zinc-lead operation on Baffin Island in the Canadian Arctic. This paper provides a description of the plant and the integrated waste heat recovery system. Data is presented detailing the actual costs of operating a plant over a period of seven years. Problems in operation are described as well as the success of the plant in meeting its objectives over the years. IntroductionNanisivik is located on the shore of Strathcona Sound at the north end of Baffin Island (Fig. I). Nanisivik Mines Ltd. has operated a 2,100 tonne per day zinc-lead underground mine and a concentrator, together with supporting infrastructure, at this location since October 1976. Annual production of 100 000 tonnes of zinc and 10 000 tonnes of lead concentrate is transported by ship to Europe during the mid -July to mid October shipping season.All electrical needs of the project are provided by the company-owned and -operated power plant. Facilities served by this electrical system are the underground mining areas, the concentrator and industrial area, a townsite, airport, and shiploading dock complex."

Jan 1, 1986

By A. M. Girodo

"Dorbyl Heavy Engineering has been manufacturing winders since 1949 mostly for the South African mining industry.Table 1 shows that the vast majority of winders have been double drum winders. At the greater depths with larger ropes being employed, it became apparent that multi-rope winders would be needed. The high stress variation in Koepe winder ropes at great depths especially beyond 2000 m, ruled out this possibility. Thus the original concept was borne for the Blair multi-rope winder where the stress level variations in the rope would be as per the well known, tried and tested double drum winder. The Blair multi-rope was also devised to increase payload by using multiple ropes.With the increasing costs of transporting men and material coupled with fact that orebodies are getting deeper, various feasibility studies have been carried out by South African mining houses. For this reason Dorbyl Heavy Engineering has done conceptual design work of both double drum and Blair multi-rope winders with diameters up to 8.5 m dia (still well within our manufacturing capabilities). These feasibility studies have looked at depths approaching 4000 m*.This paper covers the typical duties leading to the choice of single drum, double drum, Koepe and Blair multi-rope hoists on South African gold mines. A brief synopsis of Dorbyl hoists in use in the South African mining industry, with some indications of future trends, will be discussed.With current installed depths of wind approaching 2500 m, the Blair multi-rope hoist has been used extensively for the heavier payloads.Some of the main considerations pertinent to the design of the Blair multi-rope hoist are illustrated together with the implications of using this type of hoist to winding depths of3000 m to 4000 m in the foreseeable future."

Jan 1, 1995

By T. Yalcin

"This paper describes a study carried out to determine the behaviour of Cu-Ni mill tailings during natural and flocculated sedimentations. Settling rates were examined under various conditions through standard laboratory batch settling tests. Flocculation was found to improve the sedimentation process significantly, but its effectiveness depended on several factors such as the pulp density of feed, the type and dosage of flocculating reagent, the pH of pulp, the intensity of mixing flocculant with tailings sand the use of stirring during compaction.It is shown that. for a sedimentation process taking place under given conditions, underflow pulp density (P) and sedimentation time (t) are related by the expression P = k.tn, where k and n are constants. A procedure is described for the use of this expression in thickener size estimations. IntroductionOften a considerable proportion of the mill feed is disposed as tailing, because the valuable mineral recovered usually forms a small fraction of the ore. Moreover, wet concentration processes result in liquid wastes that are several times more voluminous than the ore itself. Thus the handling and disposal of these wastes become an important cost item in most milling operations. The principal unit process employed in tailing disposal is solid-liquid separation which is traditionally carried out by gravity sedimentation in thickeners or tailing dams. Direct disposal of tailings into tailing dams is common practice where sufficiently large areas of land are available but it frequently becomes more economical or practical to densify the tailings in a thickener beforehand.Successful thickener operation depends essentially on correct thickener size which is in turn governed by the sedimentation characteristics of the tailings handled. Flocculation can aid the sedimentation process and bring about significant savings in thickener size, but its effective use requires a detailed study to identify the optimum conditions of application."

Jan 1, 1988

By A. C. Headon, K. W. Lam, D. P. Dautovich

"Microbiological activities affecting the performance of materials have been encountered in diverse situations within Ontario Hydro. Case histories of bacterial problems which are presented include ground rod corrosion at transformer stations, corrosion of a bare steel cooling water intake structure in Lake Huron and corrosion of steel components in a nuclear generation station vacuum building. Possible microbiological activities which may affect the corrosion behaviour of containers for the disposal of nuclear fuel waste in the future are discussed, as are bacterial actions suspected of causing an odour problem in residential water heaters.IntroductionBacteria are ubiquitous. Except by use of sterilization methods, bacteria -free environments are no t possible to find. Bacteria lie dormant in hostile environments, spread easily through air and water currents and reproduce rapidly under favourable conditions. Although different types of bacteria have different preferable conditions for growth, they are highly adaptive and in general, whenever there is a source of water and carbon (carbon dioxide or organic matter), there will be bacterial activities . These activities often induce or enhance costly metallic corrosion in industries and water odour problems in rural water supplies . Underground structures and systems in contact with natural water or water containing organic matter are most susceptible to bacterial attack.The types of metal-degrading bacteria , their characteristics and the conditions for growth have been reviewed extensively in the literature(1,2,3). There are several often encountered groups of bacteria which, through their metabolic processes, may lead to the degradation of metals. A large variety of bacteria produce corrosive in organic or organic acids as waste, such as the well known formation of sulphuric ac id by aerobic sulphur oxidizers . Anaerobic sulphate reducers produce hydrogen sulphide which is corrosive and has an obnoxious smell, slime-forming bacteria from slime which shelters sulphate reducers and iron bacteria oxidize ferrous to ferric ion which precipitates as hydrated oxides creating oxygen concentration cells . The following are bacterial problems encountered in Ontario Hydro. Although the number of recognized cases has been few, they show the diversity of location and environment where bacterial problems could arise. These include ground rod corrosion at transformer stations, corrosion of bare steel in a water intake structure, corrosion of steel in a nuclear generation station vacuum building and an odour problem in residential hot water tanks. In addition, possible bacterial- enhanced corrosion in containers for future disposal of nuclear fuel wastes are also discussed."

Jan 1, 1984

By Earl Gebhardt

The planning and design of mining panels in the Potash Corporation of Saskatchewan Inc., Lanigan Division mine Block B involved a number of investigative techniques. The techniques utilized to gain insight into the viability of mining included 2-D and 3-D seismic surveys, longhole drilling, exploration wells, photolineament, magnetic and gravity surveys, and actual room excavation.

Feb 1, 1993

By R. J. Mitchell

"A lest apparatus has been developed for obtaining the relations among confining stress, porosity and percolation rate for hydraulic sand backfills. The apparatus can also be used to evaluate internal drainage characteristics and the effects of partial saturation on percolation rates. The test apparatus, test procedures and typical test data are presented in this paper.IntroductionAlthough the standard percolation test has become an accepted method of evaluating the drainage characteristics of hydraulically placed tailings backfill, it is recognized that the test results require considerable interpretation due to the following factors: (I) The results can be markedly influenced by varying sample preparation procedures, which vary the amount of material segregation in the sample . In particular, a thin layer of slimes on the top of a sample can control the flow of water into the sample. Wall edge effects can also affect the test results. (2) The in-place porosity of the backfill is not duplicated in the test sample and empirical formulae must be used to estimate the variation of percolation rate with porosity. (3) Internal drainage characteristics and the percolation rate of partly saturated fill cannot be evaluated in the standard percolation test.In addition to eliminating these problems, the compression percolation test apparatus also provides additional data on the mechanical properties of the backfill. Compressibility (or bulk modulus) is measured at different stress levels during the course of a test and this information can be used in evaluating the usefulness of the fill in providing ground control and in limiting ground subsidence. The engineering design of mine backfill is becoming an important part of the over all design of underground mine operations. The design problems are sufficently different from conventional civil engineering soil mechanics problems that new test methods and design procedures are required."

Jan 1, 1981

By B. M. Das, F. Claridge, V. K. Garga

Coal, as well as a large part of other minerals in Canada, is produced by surface mining methods. This has resulted in short and long-term accumulation of waste rock in dumps. Two main problems arise from the flow of water through these dumps: stability of dumps and the impact on stream flows. In recent years, a number of mines have started placing waste rock in valleys for general disposal or far constructing mine access road ways. All these have created challenges in the following areas: effective design of dumps and flow-through dams; stability monitoring of the structures; environmental impacts downstream by way of increased amount of fines in suspension, sedimentation, and toxic substances; and long-term status of flow and flood. Similar situations also exist in many civil engineering structures. This paper discusses the status of rock drains and the immediate and future research needs.

Jan 1, 1990

By Gary Hawthorn

"Laboratory testing, by Lakefield Research determined that, in spite of the relatively high pyrite content of the Golden Rose (GR) orebody, it would respond well to gravity concentration followed by either direct cyanidation or cyanidation of a flotation concentrate.Economics favoured the former choice which became the adopted process flowsheet.During the latter stage of the feasibility study, the Dekalb 500 tpd copper flotation mill became available in the Highland Valley of British Columbia. This plant was purchased by Emerald Lake Resources, and was moved to the Golden Rose minesite.The crushing and grinding circuit were retained and the original flotation circuit was replaced with a 400 mtd gravity plus cyanidation circuit. The plant commissioning commenced in August 1987, and by early September was processing 300 tpd.HistoryThe Golden Rose Mine was operated by Cominco during the period 1935 to 1941 processing 146000 tons grading DAD oz/t Au at a rate of 110 tpd .The process flowsheet consisted of gravity plus amalgamation followed by cyanidation.Metallurgical TestingThe underground mining areas were below the level of Emerald Lake, and had flooded on abandonment in 1942.Samples for metallurgical testing were collected from exposed faces underground once the mine had been dewateredin 1984.In spite of the anticipated high pyrite content of the ore samples, it was apparent from the success of the previous operation that the pyrite did not interfere with the gold recovery.Laboratory testing, at Lakefield, determined that, from a technical perspective, two metallurgical options existed, as shown in Tables I and 2.Note that the very high pyrite content of the ore precluded the possible direct marketing of concentrate. The process flowsheet, therefore, had to contain a cyanidation circuit for the operation to succeed financially.Although the anticipated metallurgy was excellent with either option, the 2.1 % increase in gold recovery with the gravity plus cyanidation option made this the clear choice."

Jan 1, 1989

By Paul Hughes

Purpose of Research ? What are the loading mechanics of paste against barricades? ? What is the capacity of the composite paste fill fences? ? Based on the loading mechanics of the paste, do the fill fences pose a risk of failure? Outline ? Glossary of Terms ? General Introduction ? Research Methodology ? Site Description ? Instrumentation Program ? Results ? Analysis ? Conclusions ? Recommendation for Future Work

May 1, 2008

By C. A. Roloff

Demands for increased grinding production, lower-grade are and limited capital have resulted in ever larger grinding mills, some as large as 36ft (/1 m) in diameter and 12,000 hp (8,950 kw). The result is often f ewer machines per plant, with a greater dependence on each machine. To meet these reliability requirements, manufacturers of mills, drives, castings and other components have had to be innovative and creative in their design. Only by thorough review of past designs and practices and by model studies confirmed in field tests can the manufacturer have full confidence in the product. Because of the great interest in large mills, a short review of larger machines is presented. This discussion covers material feeding, bearings, the rotating element, drive trains and material discharge.

Jan 1, 1979

Agenda ?Trends in Wireless Technology ?Success and Opportunities ?Improving plants efficiency ?Improving plants reliability ?Improving plants safety and security ?Wireless Ecosystem ?Lessons Learnt / Recommendations Why Wireless? ?Lower cost (no wiring cost) ?Flexibility (no wire) ?Standards-compliant wireless devices major factor enabling growth:?Standard WLAN (IEEE 802.11)?Wireless field I/Os (IEEE 802.11, ISA100.11 and WirelessHART) ??Wireless adoption will become a milestone that will rival the introduction of Fieldbus and the distributed control system (DCS) in its importance.? ARC Advisory Group

May 1, 2009