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By P. A. Verhey

"This paper describes a series of wear-resistant ceramic materials which have been successfully used in the mineral processing industry in Canada. Applications include use with metallic ores, coal, potash and asbestos, and in other processes where wear degradation is of major concern. The paper will also deal with considerations involving the selection of the different ceramic materials available. It will cover the installation of ceramic materials on support structures under varying process ' conditions, as well as the other physical and chemical factors which have to be taken into account.IntroductionIn the mineral processing industry, large volumes of ores tailings and other materials are handled. The abrasive nature of most of these materials results in extensive wear to both handling and processing equipment.Wear ratios versus cost, production losses due to down time and wear-resistant material suitability for a given application all demand particular attention when viewed against the need for increased efficiencies in existing processes. As a consequence, a very active continuous search for materials with improved wear resistance has been carried out for many years.In this search, starting about 20 years ago, dense ceramic materials were tested and evaluated in certain applications, notably in the iron ore and asbestos operations in Eastern Canada. As a result of substantially better performance both in continuous extended life and ultimate economics realized , wear-resistant ceramic applications developed progressively in many other processing applications, replacing traditionally used materials.In the vast majority of wear-resistant ceramic applications, considerable extended life over previously used materials was established. This invariably was not just a fractional increase but, in most cases , in factors of double, triple and often all the way up to 18 and 20 times the life of alternative materials used previously. In certain applications, extended life could not be measured and appears to be indefinite.Obviously, as a result of such experiences, the progressively wider use of wear-resistant ceramic materials is now an established trend."

Jan 1, 1981

By H. K. Fredrickson

"Midwest Joint Venture (MJV) owns a high-grade uranium deposit in northern Saskatchewan. The deposit is located too deep below surface to be mined economically by open pit methods, and as a consequence, present plans are that it will be mined by underground methods. High-grade uranium ore of the type at MJV, encased in weak, highly altered ground and with radon-rich water inflows, has not before been mined by underground methods.The test mining phase of the project, completed in 1989, had three objectives: 1. to evaluate radiation protection requirements associated with the handling of large quantities of radon-rich water and mining highgrade uranium ore in an underground environment; 2. to investigate the quantity and quality of water inflows into the mine; and 3. to investigate ground conditions in and around the ore zone as an aid in determining the production mining method to be used.With information gained from the test mining project, a mining method for the production mine has been devised. Level plans have been drawn up, ventilation system designed, pumping arrangements made and methods of ore handling considered. All this is to be done in a manner that will be safe for those doing the work underground. Some of the mining methods planned are felt to be unique in that they are designed to cope with mining problems not known to have been encountered before. New problems underground have required new methods to handle them. Remote drilling, blasting, mucking and backfilling form the basis of the planned mining method."

Jan 1, 1992

By P. C. Garg

"IntroductionThe Central Mine Planning and Design Institute (CMPDI) of India, started planning the extraction of thick seams highly susceptible to heating in 1977by the French method of sub-level caving and/or multi-slicing. Nitrogen flushing was proposed for inhibition of heating by the author in one such project - the Kotadih colliery.Inhibition of heating was unheard of in the Indian coal industry before 1977-78. The usual practice was to seal off a district or a part of the mine or the entire mine when spontaneous heating occurred. With very little equipment in a normal bord and pillar district and a low production rate, the financial loss in capital assets and in production did not warrant any serious thought for inhibition of spontaneous combustion. With the planned advent of longwall mining, particularly sub-level caving, with heavy capital investment as well as high production potential, the sealing of a longwall face due to spontaneous heating could not be considered an appropriate solution.Principle of Inhibition of SpontaneousCombustionFrench engineers have established that a fire will not break out when oxygen is 15% or lower in the general body of the air. However, once a fire starts, the percentage of oxygen has to be reduced to 2% - 4% to extinguish it. It is this principle which has been used at Blanzy Coalfield in France to inhibit heating and it is claimed that this has retrieved the integral sub level method of mining. Nitrogen infusion has been used in Frence since 1978 to keep the oxygen content below 14% in the goaf."

Jan 1, 1987

By A. Scheltema Beduin, H. Oterdoom, A. Haaks, C. Kempe, A. Liedtke

"For the Kazchrome DC Ferrochrome plant, SMS-group specifically designed an electrode column that would minimize downtime. Special features include the possibility for on load electrode jointing, on load slipping, and back-slipping. Electrode consumption is strongly related to furnace load and impedance, and is very low at high loads, which makes the graphite electrode an alternative to consider even in AC applications. The electrode could also be applied in other DC applications, as for example TiO2 slag, the novel Conroast process, or (twin) DC FeNi furnaces, and could possibly be installed during bigger shut downs. This paper will describe some of the design considerations and operational performance data on this novel column in the FeCr industry that could also be of interest for the FeNi or PGM industry if these would continue to develop towards DC technology.INTRODUCTION Every DC furnace has a cathode and an anode. The anode applied is commonly known as the Concast design, though the original design was by ABB who handed it over to Concast, subsidiary of the SMS-group. Some well-known DC furnaces outside the steel industry where the Concast bottom has been installed are listed in Table 1 as well as a few other key design features.Sidewall cooling and some other data have been left out for reasons of space, and being a lesser relevant design feature to this paper. HES stands for Hollow Electrode System, in which feed is charged through an electrode. Table 1 is built up chronologically according to first start-up date. Below comments are given to briefly explain some of the columns in Table 1: •,“Arm” in the “Cathode” column means that the design of the cathode holding and regulating mechanism consists of an electrode arm as depicted in Figure 1. •,Charging is relevant as some operations started with HES charging, whereas recently most new operations have started without HES but only charging chutes, of which at least some are close to the electrode and possibly others installed closer to the sidewall. •,“Dome” in the “Roof” column means that the design of the roof involves a center piece that can be exchanged if worn. •,The optimal roof design still seems to be a topic of debate, where no design is without problems."

Jan 1, 2017

By Richard D. Moffett

The MineSight® Implicit Modeler arms geologists, engineers and surveyors with a better approach to 3D modeling. Use the tool to quickly retrieve a 3D wireframe from drillhole data and onscreen interpretation. Generate faster and more informed decisions to guide future work and improve reproducibility of results. Implicit Modeling is a mathematical surface fitting method that interpolates points to give a smooth and realistic fit. Control results by mixing planar, sectional and non-orthogonal polygons or polylines, as well as drillhole information to create solids or surfaces. The outcomes are particularly valuable to identify ore body trends, generate 3D contours of drillhole intercepts, or produce cut-off 3D maps. MineSight Implicit Modeler (MSIM) is fully integrated in MineSight?s robust and versatile suite of products, allowing you to interpret, interpolate and calculate while moving between applications. It connects seamlessly with the MineSight Torque SQL database, offering access to extensive filtering options. MSIM makes modeling much faster, allowing geologists more time to analyze data and test theories. The presentation will reveal how MSIM complements MineSight?s geomodeling workflow.

May 1, 2013

By J. W. Smith, J. G. Eacott, D. H. Napier

"Three hydrometallurgicat processes (Noranda chloride leach, B. C. Research biological leach and Sherritt-Cominco activated oxygen leach) and the Noranda pyrometallurgical process have served as the basis for design projects in the final year of the chemical engineering program at the University of Toronto. Each member of a team of five or six students devotes about 200 hours to the project and the final report is expected to include an economic analysis.None of the processes has been developed to full- scale plant, nor, in the case of the B.C. Research and Noranda processes, were pilot plant data available. Nevertheless, the designs developed provide a useful basis for a preliminary estimate of capital and operating costs and for a preliminary assessment of project feasibility.This paper discusses the approach used in the design projects with respect to engineering and economic aspects, and outlines the educational features and benefits of such a program as well as some of the problem areas that arise.IntroductionAs part of the undergraduate degree course in chemical engineering at the University of Toronto, students devote some 200 hours to a design project in their final year. Hydrometallurgical processes, not yet proven at the commercial scale, have been selected for study. The students are required to develop laboratory and / or pilot scale results into a conceptual plant design, using sound engineering principles. Capital and operating costs are then determined and a preliminary feasibility study and economic analysis are carried out."

Jan 1, 1986

By Nosa O. Egiebor, Kafui Nyavor

"The effectiveness of sulphuric acid, nitric acid, and hydrogen peroxide pressure oxidation on the cyanide extractability of gold from a double-refractory concentrate is presented. Whileover90% of the sulphide content could be oxidized by either of the two acid pretreatments, only 65% was achieved by the peroxide oxidation. Carbon oxidation by both acid and peroxide pressure oxidation were less than 15%. Although the peroxide pressure oxidation pretreatment resulted in much lower sulphur and carbon oxidation, it gave pretreated residues with decreased levels of preg-robbing activities and higher gold recoveries during subsequent cyanidation, thus indicating some deactivation ofthe preg-robbing carbon during pretreatment with hydrogen peroxide. The refractoriness due to carbon preg-robbing activity was found to contribute more to the refractory behaviour of the concentrate than the occlusion of gold particles by the sulphide mineralization.IntroductionGold ores and concentrates are classified as refractory when a significant portion of the gold content cannot be extracted efficiently by conventional cyanidation, even after fme grinding (Weir and Berezowsky, 1984); (Demopoulos and Papangelakis, 1987). The refractory behaviour of precious metal ores and concentrates is generally attributed to two main factors: The presence of carbonaceous materials which could cause preg-robbing activity during cyanidation (Zaitseva et al., 1973); (Nice, 1971); Scheiner et al., 1971); (Eisele et al., 1983), or occlude gold-bearing minerals (Wells and Mullens, 1973); (Gasparrini, 1983); (Chen and Reddby, 1990), and the occurrence of sulphide minerals which can occlude gold, thus reducing the access of lixiviants (Schwartz, 1944); (Weir et al., 1986); (papangelakis and Demopoulos, 1990); (Michaelis, 1989); (Schweigart, 1965). When the refractoriness is due to a combination of these two factors, the ore or concentrate can be referred to as being ""double-refractory"". Because of the rarity of gold ores exhibiting this double-refractory phenomenon, only a few studies have been carried out on their suitability for pretreatment by existing techniques."

Jan 1, 1992

By Ken Wood, Luc Duval

"The development and operation of the milling circuits treating the different Selbaie orebodies are discussed in this paper. The project is reviewed from metallurgical evaluation through construction to present operating status. The current flowsheets are described, with discussion of some unusual features.IntroductionThe Selbaie concentrator commenced initial production in August 1981, treating underground B zone copper ore in a single 1500 t/d circuit. Throughput was increased to 1650 t/d in 1985. The mill was expanded in 1986 to treat ore from the A-I zone open pit; an independent circuit was added to selectively treat 5000 t/d of copper-zinc ore. Current total mill throughput through both circuits averages 7200 t/d with the production of approximately 270 t/d of copper concentrate and 230 t/d of zinc concentrate.This paper describes the stages involved in bringing the project from initial laboratory testing to its current status as one of the most important producers of silver, copper and zinc in Quebec and a major employer in the region."

Jan 1, 1990

By M. Hall

"SomarioEl circuito de molienda a Selbaie consta de molino semiaut6geno en un circuito cerrado y molino de balas en un circuito cerrado. El amperaje del motor de se usa controlar el tonelaje el molino. Este sistema estabiliza el circuito pero no mejora activamente el rendirniento del circuito. Se desarroll6 auxiliar el rendimiento del circuito un sistema experto en manipular las objetivos de existir control proporcional-integral. Se ejecut6 el sistema con el Comdale /C conjunto del sistema experto y ha side funcional hace tiempo el mayo de 1992. El sistema experto ha resultado en un aumento en tonelaje de 7tph y una disminuci6n de $210,000 en el caste anual de media de molienda. Se describe el desarrollo del sistema y los provechos derivar se presenta.AbstractThe grinding circuit at Selbaie consists of SAG mill and ball mill closed circuit grinding. The SAG mill motor current is used to control throughput. This system stabilizes the circuit but does not actively optimize circuit performance. An expert system was developed to aid the optimization of the circuit by manipulating the set-points of existing PI control loops. The system was implemented with the Comdale /C expert system package and has been on line since May 1992. The expert system has resulted in a net increase in tonnage of 7tph and a decrease in annual grinding media costs of $210,000. The system development is described and the benefits derived are presented."

Jan 1, 1994

By Robert B. Parsons

"This month, Tax Notes focuses on two features which can potentially ""dress up"" a new issue of common shares to make the shares more attractive to investors. Attaching warrants to a share issue is a relatively common practice, and recent years have seen an imaginative variety of different kinds of warrants, some of which can be subject to somewhat different tax treatment . A less common financing strategy which certainly deserves some consideration involves the possibility of utilizing ""Share Purchase Tax Credits "" in conjunction with a new share issue.IntroductionPrevious subjects covered in Tax Notes have dealt with flow-through shares and other tax angles which can make equity issues more appealing to potential investor s. Two other techniques which can add zest to a new stock issue involve the utilization of warrants and ""share purchase tax credits"" (or SPTCs). This article takes a brief look at the better known subject of warrants and the lesser known matter of SPTCs.Of course, this paper presents only a relatively general summary of the income tax implications of warrants and SPTCs, and is not intended to be a definitive commentary on all of the detailed and complex tax issues that might be relevant in the circumstances."

Jan 1, 1985

By B. Das

"Computers have been used extensively in the mineral industry in exploration, reserves calculation, mining technology, mineral processing, etc. With respect to coal mining, there are also various applications for evaluating rock slope stability of open pits, design of open pits, underground operations, mine ventilation, ground control, data processing and management information, operations control and certain technological applications. Mine ventilation appears to be the field in underground coal mining touched on most; on the other hand, underground coal mining methods evaluation is represented only sparingly.It is therefore essential to review the status of the computer in underground coal mining methods evaluation in order to define its scope for further application. The paper discusses the roles of the mining engineer, programmer, computer operator and analyst as well as that of the computer. The important parameters will be identified and discussed along with their application for different underground coal mining methods, with their individual unit processes. Mainly, longwall face operations have been covered. Although many models have been of academic interest, they can be considered as important steps in a transition stage which will be followed by more practical applications for computers for underground coal mining method evaluations in the future. This calls for a coordinated effort from all concerned."

Jan 1, 1981

By J. E. Udd, L. B. Geller

"Responding to requests by the Canadian mining industry and the mine regulatory authorities, the Canada Centre for Mineral and Energy Technology (CANMET) undertook a major research project on evaluation of wire rope testing in 1986. The objectives were to document, analyze, and clarify - in basic operational terms the reasons for ongoing mine shaft wire rope failures that occur despite mandatory non-destructive testing (NDT) with electromagnetic (EM) instruments on a routine basis.The project's investigative scope and depth was unprecedented. It could not have been successfully completed without the wholehearted cooperation of industry, research organizations, and mine-inspectorates at both national and international levels.The project's goals were attained. II was shown that, at present, the problem areas in Canada are oj a human , rather than of a hardware-related nature. Consequently, the principal recommendations are concerned with a more widespread, more uniform and thorough operator training and certification process at industrial and regulatory levels. Secondary suggestions concern areas of hardware-related improvements.In this paper an up-to-date general overview is given of the major project results. A n extensive reference list is also provided of papers that contain all relevant documentation in detail."

Jan 1, 1992

By Kremena Dedelyanova

The paper presents research of mechanism for the creation of air bubbles in vibratory a column flotation machine. Factors are discussed that influence the increase in the duration of the bubble in the area of contact with the mineral particles. Formulas are derived for the parameter effect of vibrations, applicable to the design of flotation machine. The collision efficiency of the bubbles in a vibratory column flotation machine is determined.

Aug 1, 2013

By J. E. Marshall

"The concept of employing a project management team to coordinate all aspects of the construction of a new resource development has gained wide acceptance. This team can be formed from within the staff of large mining companies or contracted from major engineering firms and consultants. The mandate of the project managers usually terminates on successful startup of the operation. For frontier mineral developments in the Canadian Arctic or in the developing countries, startup and the initial year of operation represents the period in which the project is most vulnerable to technical, political and managerial problems. A complete change of the management team or the retention of the construction project managers and the resulting cost combined with the breakdown of organizational accountability within the operating staff .are unnecessary management problems.Independent project management services provide the commitment necessary to sustain the continuity of management through all project phases. Efficiency and the ability to make decisions quickly are characteristics of the many successful small mining companies. These qualities are necessary in the project management group, which will be responsible for up to 90% of the preproduction costs.Continuous project management in the construction and operational phases of a mineral development are common in the iron ore industry, but remain anomalous in the base metal, energy mineral and industrial mineral fields.The Nanisivik project on Baffin Island in the Canadian Arctic is used to illustrate the advantages of total project management through construction and operation.Total project management has further potential for foreign interests and financial and utility organizations desirous of participating in the Canadian mining industry, but with no direct involvement in the construction or operating management. Participation agreements in the operating phase of a project can be negotiated to have management fees related to both the production and the profits of the enterprise."

Jan 1, 1980

By E. Contestabile, T. R. Craig

"This report describes the development and effective use of shaped charges as part of the Elliot Lake Mine Roof Stability Project to remotely remove the heads from roof bolts. With a slight modification, these same shaped charges are being recommended f or use to the Brunswick Mining and Smelting Corporation Limited (Mining Division), to cut steel cable bolts.IntroductionThe Canadian Explosives Research Laboratory (CERL) often receives requests to cooperate in solving problems encountered in private industry or other sectors of the government. CERL is equipped to design and test explosive and pyrotechnic devices and the policy is to treat each case individually.The first case reported evolved from a request from a sister laboratory at Elliot Lake. The intent was to remotely remove the head s of roof bolts as part of a mine roof stability project. The device designed for this use was 1000,70 effective in the laboratory and 80% effective in the mine.The second case reported results from a request from a private mining company knowledgeable of the Elliot Lake Project. Their requirement was to remotely cut cable bolts. This request was first treated as presenting a new problem. The solution, however, proved to be very similar to the former."

Jan 1, 1985

By Paul Delottinville, Maynard Hall, Henry Hillier

"An expert system application for supervisory control and optimization of the indurating process at the Iron Ore Company of Canada (IOCC) has been developed and installed in closed-loop. Prior to the installation of the expert system, the indurating machine was rebuilt and the instrumentation revamped. A Foxboro I/A Distributed Control System (DCS) was installed for regulatory control, and a new control strategy configured. The modernization of the regulatory control has resulted in significant improvement in both production rate and product quality. Expert system control was implemented in September 1996. Preliminary indications are that the expert system has further improved the consistency of product quality, enhanced fuel efficiency and increased productivity. The expert system considers both wet and dry sections of the circuit, and its optimization scheme is driven by pellet tumble index and compression strength. Statistical Process Control (SPC) rules were implemented in the expert system as part of the quality analysis and control scheme. The expert system application was developed and delivered using the Comdale Expert Optimizer (CEO), and has been in continuous closed-loop control since its installation. The system development and implementation is described, and preliminary benefits are presented..... IntroductionIn early 1996 the Iron Ore Company of Canada (IOCC) contracted Comdale Technologies of Toronto to develop and implement a real-time expert system for optimizing the indurating pelletizing furnace at our plant location in Labrador City, Newfoundland.The decision to install the expert system has been timely. Like many other resource-based industries in increasingly competitive markets, IOCC recognizes the need to find ways to improve the efficiency of our production process and ensure that product quality is maintained at the highest levels. With the Labrador City plant producing 11 million tons of iron ore pellets annually, implementing the best technology solutions to meet these objectives is critical."

Jan 1, 1998

By Richard C. Corson

"Modern microprocessor systems make it possible to use several variables to anticipate changes in the process and to react with responses before upsets can be magnified by the process or by control action.Through tighter control, ""insurance"" can be eliminated from process set points without affecting product quality. In actual operation with a traveling grate furnace this control philosophy has produced savings of up to 20% in fuel consumption and 8% in fan power usage while producing a more consistent quality product.IntroductionA straight grate indurator, or pelletizing machine, consists of a continuo us moving train of pallets on which a feed stream of unfired, ""green"" pellets is deposited on a hearth layer o f fired pellets. This bed moves through several zones in the furnace where it is dried, preheated, fired and cooled by streams of gases which are pulled or blown through the bed by a series o f large process fan s. Control systems for straight grate plants are designed to maintain gas flow through the machine to ensure that sufficient time and heat are available to raise the temperature of the entire green bed to 1300°C where hematite bonding take s place.For the pas t two year s a new approach to control systems using microprocessor-based instrumentation has been designed and tested in an existing plant with a straight grate indurating furnace processing magnetite ore. The purpose of the test was to determine the most efficient operating setpoints for all levels of production above fifty per cent of design capacity. Through a combination of feed forward control, variable setpoints and additional loops, significant savings have been realized. Thus far the project has taught us much about control systems design and operation, energy utilization, and the process itself."

Jan 1, 1983

By J. M. Beeckmans, S. G. Butcher, M. Goransson

"The counter-current fluidized cascade is a novel and potentially efficient pneumatic gravity separation device. Data are presented on over 150 runs of cleaning Alberta thermal coals, covering several size ranges. The coarser sizes of coal were processed in admixture with a fluidizing medium consisting of 0.5-by 0.1-mm hematite (or magnetite) and limestone particles. The partition curves for coal particles larger than about 3 mm, mixed with fluidizing medium, showed that the sharpness of separation achievable with the cascade approaches that of wet heavy medium processes, whereas with particles in the size range of 3 by 0.6 mm the sharpness of separation was comparable to that of a Baum jig. Useful cleaning was also achieved with particles smaller than 0.6 mm , Throughput rates of up to 11 tonnes per metre width of cascade per hour were achieved, with no indication of a deterioration in performance.IntroductionPneumatic coal beneficiation has steadily lost ground vis-a-vis hydraulic beneficiation during the past quarter century, primarily because of the sharper separations achievable with the latter methods. Nevertheless, there are certain inherent advantages of pneumatic separation methods which would give them an advantage in the market place were it possible to increase their efficiency to be technically competitive with those of hydraulic processes. These advantages are a dry product, resulting in a higher calorific value per ton, and avoidance of the problems associated with treatment and storage of process waste waters. Also, although it may be necessary to dry the raw coal prior to pneumatic processing, the dry rejects produced constitute an ideal fuel for a fluidized-bed combustor, which could provide heat both for drying the coal and for other purposes."

Jan 1, 1982

"The Dome Mine, located in South Porcupine Ont. has been in operation since 1910 and is owned and operated by Placer Dome Inc. The current milling facilities were constructed in two phases with the first being commissioned in 1982. It consists of a grinding, gravity separation, thickening, and leaching circuits. The second phase was commissioned in 1988 with the addition of the CIP, stripping, electrowinning, and carbon regeneration circuits.It is now common practice in the gold processing community to add liquid oxygen to leach circuits to increase both recovery and kinetics. Along with these benefits the metallurgical group at the Dome realized the potential to replace compressed air with liquid oxygen as a source of oxygen for the dissolution of gold. A plant trial of liquid oxygen was undertaken during the fall of 1991. The results of this first test were favourable enough to warrant further investigation, and a second plant trial was conducted in December 1991.The data generated as a result of each trial revealed that oxygen could be economically substituted for compressed air as a source of dissolved 02. The energy savings in required horsepower enabled a rapid payback period. Thus the project was approved in the spring of 1992 and l should be operational during the final quarter of 1992. INTRODUCTIONIn a continuing effort to reduce operating costs and improve recovery at the Dome mill it was decided to investigate the feasibility of adding liquid oxygen (02) to the leach circuit. It is now common practice in the gold processing community to add 02 to the leaching process to increase both kinetics and recovery. It was anticipated that an increase in kinetics would allow us to eliminate one or more leach tanks while maintaining acceptable recoveries. The metallurgical group felt that along with these benefits, the potential was also there to reduce power consumption through the reduction in the processing of compressed air which is quite costly (12 cents/1000 cubic feet per minute in 1991)."

Jan 1, 1993

By D. Marotte, M. David

"A new exploration procedure is proposed for volcanogenic massive sulphide deposits of the Abitibi belt. ""Samples"" of acidic volcanic rocks (Si02 > 60%) were compiled from the literature. From the 574 samples collected, 322 were used in each of a number of experiments. Forward inclusion linear discriminant analysis performed on the untransformed geochemical data shows a general depletion in Na20 and CaO along with an enrichment in MgO for a ""proximal"" group of samples relative to a ""distal"" one. The percentage of misclassified samples reaches 20% to 30%, but test sets shows good stability.The exploration procedure was applied to the Normetal deposit, where the authors took 160 samples during the summer of 1977. It quickly leads to the definition of targets for more detailed exploration together with a good recognition of the old known deposit.IntroductionVolcanogenic massive sulphide deposits in the Abitibi belt (Quebec) are mainly found in rhyolites or acidic pyroclastics in the uppermost portion of a calc-alkaline volcanic series (Descarreaux, 1972). The deposits are thought to have formed syngenetically by the action of volcanic hydrothermal exhalations during the waning episode of a felsic volcanic cycle (De Rosen Spence, 1976). Alteration pipes of disseminated sulphides are commonly present. Metal deposition from hot springs, initiating convection cells in a submarine environment, may have been the dominant process in ore formation (De Rosen Spence, 1976)."

Jan 1, 1981