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By R. G. Eggert

"A critical element, as the term has come to be used, provides essential properties to a modern engineered material and is subject to supply risk. The rare-earth elements became perhaps the most prominent of the critical elements in recent years because of their important uses in permanent magnets, advanced lighting, and military materials; the geographic concentration of production in China; and the dramatic run-up in prices in 2010-2011 followed by price collapse between 2011 and 2016. Yet criticality extends beyond the rare earths. What is critical depends on your perspective – who and where you are, and when you ask. This paper reviews the many perspectives on, or faces of, critical elements. It compares and contrasts perspectives of industry (General Electric), national or regional manufacturing sectors (Japan, European Union), emerging energy technologies (as seen by U.S. Department of Energy and, separately, Joint Research Centre of the European Commission) and the world as a whole (as evaluated by academics). This comparison reveals a diversity of not only perspectives but also methodologies and time frames of concern.INTRODUCTIONRare-earth elements appeared prominently in the news in 2010 and 2011 because of the dramatic increase in their prices; their important uses in permanent magnets, advanced lighting, and military materials combined with the geographic concentration of production in China, which reduced export quotas significantly. Rare earths became the most prominent of what have become known as critical elements or materials – that is, those that provide essential properties to modern engineered materials and yet are subject to supply risks.Yet criticality, the state of being both essential and subject to supply risks, extends beyond rare earths. What is critical depends on your perspective. This paper begins by reviewing a little history and presenting a general conceptual framework from which to think about critical materials. It then reviews the many perspectives on, or faces of, critical elements – corporate, national, and global, as well several that focus on emerging energy technologies. The paper concludes with thoughts on what to do to mitigate the potentially negative effects of the supply risks associated with criticality."

Jan 1, 2016

By Warwick Bullen

A hypothetical economic model has been developed for diamond projects in the Canadian Arctic using data from recent exploration and mining projects. The model reflects economic conditions as it applies to the diamond mining industry in the Canadian Arctic at the present time. The economic model captures pre-production expenditures, production data, and post-production costs. Before- and after-tax cash flows are derived from the data along with the relevant economic criteria. From the corporate perspective, the model provides guidance as to the minimum size and/or in-situ value per tonne requirements of targets being sought in order to ensure economic success and probable exploration and development expenditures. From the government perspective, the model provides an indication of income and mining tax revenues that can be expected from a particular diamond project. The model shows, on average, diamond projects in the Canadian Arctic are expensive to explore for and develop, but are economically robust. They generate great economic return for mining companies and significant amounts of tax revenue for governments. The fact that diamonds can be transported directly from the mine site by air makes them particularly attractive targets for mining companies that operate in the Canadian Arctic.

Apr 1, 2005

By A. Vervoort, A. Govaerts

Geostatistical concepts are often difficult for students to understand, even those with a strong mathematical background. One of the main problems is the link between the variation of the parameter value in space or time and the calculated experimental semivariogram. Another challenge is differentiating between directional and omnidirectional semivariograms and their interpretation. For these reasons, interactive tools were developed based on the free public domain software R. The use of these interactive tools is limited to educational situations only (i.e., to visualize basic concepts). The interactive modules can be accessed at www.bwk.kuleuven.be/geostatistics.

Jan 1, 2014

By Farid Mirahadi

Forecasting productivity of construction operations is a difficult but crucial task in planning construction projects. Over the past decades, many models have been developed to forecast productivity for different construction operations. Models made up of several functional relations and controlled by a specific number of control rules are more in line with human reasoning and logic. Neural-Network-Driven Fuzzy Reasoning (NNDFR) structure as one of these models shows a great performance for modeling datasets among which clear clusters are recognizable. Lack of the compatibility of conventional NNDFR with fuzzy clustering algorithms besides the insufficient attention paid to the optimization of number of clusters in this model, created a potential area for further research. The main contribution of the proposed model is to develop a modified NNDFR system to model construction data. To this end, Fuzzy C-Means (FCM) algorithm is substituted for K-means in NNDFR structure, and its parameters such as the number of clusters and weighting exponent are optimized through genetic algorithm. The proposed model is further verified through simulation of a construction operation in which several qualitative and quantitative factors are considered. Its implementation to the case study shows a considerable improvement of model performance with lower Mean Squared Error (MSE). The developed model assists researchers and practitioners in utilizing historical construction data to forecast productivity of construction operations with a high accuracy that could not be obtained by traditional techniques.

Aug 1, 2013

By Robert K. Jonas

Mining companies can improve production and reduce costs by using the best available technology to control their operations. Many mines are challenged to use multivariable predictive control due to limited experience or staffing, as well as being concerned over the robustness and sustainability of predictive controls. As a result many mines are not realizing optimal performance from their assets, and thusly are not realizing the production increases or cost reductions that this technology can deliver. Over the past few years, the application of multivariable model-based predictive control has gained acceptance in many mining processes and has proven to be robust and sustainable for some of the most challenging mining processes. New automated modeling and performance monitoring software have greatly simplified the effort to implement and maintain these solutions. In addition, many progressive companies have chosen to co-source the implementation and service of these solutions to assure project success and continued benefits stream. This technology has been successfully applied to a wide variety of processes; grinding mills, alumina digestion, CCD washer and thickeners, kilns, calciners, roasters, flash smelters, heat exchangers, evaporators, and most recently in the demanding process of flotation. This paper discusses the state-of-the art in advance control technologies in the mining industry, including the impact of these technologies on maximizing benefits, and implementing best practices for long term sustainability. Benefits from recent multivariable predictive control applications in copper mining will be reviewed, and the use of the latest predictive control technologies and practices in mining will be discussed.

Oct 1, 2009

By J. M. Cummings

The importance of controlled sand properties to the production of quality castings has been recognized by foundry men for many years, but the maintenance of requisite standards results in a relatively high sand consumption, which in steel foundries, for instance, may range from half a ton to over one ton of sand per ton of finished casting. During the war, obtaining and maintaining adequate sand supplies became a serious problem in many foundries, owing to increased wartime production and serious 'bottlenecks' in transportation. As a result, considerable interest was aroused in the possibilities of various sand reclamation systems by which up to 85 or 90 percent of discarded sand may be returned to a usable condition. During the past five years or so, a number of sand recovery installations have been made by both ferrous and non-ferrous foundries in Canada and the United States, and have resulted in substantial reductions in sand costs in every case. The possible benefits of sand reclamation are particularly apparent in British Columbia where no suitable sands for steel and heavy iron foundries occur naturally, and where freight costs on imported sands are considerably higher than initial selling prices. This is well illustrated by the fact that silica sand, which sells for about $2.00 per ton at pits in Illinois, is laid clown in British Columbia for around $11.00 or $12.00 per ton. The operating costs quoted for certain of the reclamation schemes, i.e. $0.25 to $1.50 per ton, may actually be no higher than the cost of waste sand disposal in city-located foundries. In view of the foregoing considerations, the British Columbia Research Council has undertaken a study of the possibilities for sand reclamation, with particular attention directed to its application in local steel foundries. No commercial occurrences of silica sand are known in the Province, and, with this in view, the Council previously investigated the possibility of recovering silica sand from local impure sands. Results were definitely encouraging, but it was felt that the present market is too small to permit economical production by the method developed.

Jan 1, 1947

By Luis Bergh, Juan Olivares, Juan Durán, Juan Yianatos

"In the last decades heuristic approaches based on logic rules have been one favored tool to control flotation units and plants on top of distributed control systems. Fundamental knowledge on flotation processes, expressed in reliable models, and programs to assure the quality of the information, contained in available measurements, are still insufficient to develop robust predictive control strategies. In this paper the idea of using simplified models, when a known disturbance is coming into the process, is explored. As a first approach, the set points of the froth depth and air flow rate controllers are estimated based on this model. Since these target predictions are only approximate, a conventional feedback expert system, based on logic rules, continues the task of calculating the set points of the distributed controllers, in order to decrease the gap between actual and desirable metallurgical targets. This combined actions permitted a fast response of the process to change the operation of the circuit when a measured disturbance is detected. This control system was implemented and experimentally evaluated in a pilot rougher flotation circuit, with three pneumatic cells, with froth depth and air flow rate controllers in each cell. Since the circuit is operated for the air-water system, a phenomenological model, with parameters estimated from industrial data, is fed on-line with real operating variables and virtual values, characterizing the feed (grades, solids%, particle size distribution), in order to predict the metallurgical targets (recovery and concentrate grade). Several cases are discussed showing the benefits of this control system and the possible improvements to work on. INTRODUCTIONToday, large size mechanical flotation cells of 100 to 300 m3 are used in rougher operation in different flotation industrial plants, in Chile and worldwide. However, in spite of the advances in fundamental research and the notable growing in equipment size, with more complete instrumentation systems, there are still a lack of reliable data for industrial flotation modeling and simulation to advance in better control systems design."

Jan 1, 2016

By Matthew S. Bingham, David H. Searle

"One of the most significant developments in environmental law has been the development of mandatory project review processes, at both the federal and provincial levels.FederalWhile, in the past, project review processes have, f or the most part, been spelled out in guidelines, the guidelines have not had the force of law. All that has changed, particularly at the federal level, with the Federal Court decisions commonly referred to as the Old Man River and Alameda and Rafferty Dam cases. These decisions, taken as a whole, are authority for the proposition that the Environmental Assessment and Review Process Guidelines Order, SOR 82-487 is a law of general application, not a mere guideline which may or may not be applied. This federal environmental assessment process first provides for a screening, and, depending upon the results of the screening process, the possibility of a public review. This federal process only applies, however, when the proposal is being undertaken by a federal department, or where the Government of Canada makes a financial contribution, or where federal lands are involved, or where a federal licence or permit is required.Bill C-78, the Canadian Environmental Assessment Act, will replace the Federal Environmental Assessment and Review Process Guidelines Order once it has been passed by Parliament. Currently the bill is being widely discussed, both between governments as well as public interest groups.ProvincialOn the provincial scene, there are three project review processes, one concerned with new mines, the second with energy projects and the third with all other major projects. The most recent initiatives taken by British Columbia are twofold. First, the Mine Development Review Process which was in the form of a guideline, has been replaced by the Mine Development Assessment Act. Second, the Major Project Review Process has been formulated and is to apply to four main categories of major projects:1. Pulp and paper production;2. Mineral smelting and refining;3. Chemical products; and4. Major ports and marinas.Energy projects are governed by the Energy Project Review Process which is legislatively mandated under the Utilities Commission Act."

Jan 1, 1991

By Steve Forgeron, Brendan MacKenzie, Kevin MacPherson

"The geological composition of strata immediately adjacent to coal seams has a significant effect on the safe and efficient extraction of coal from underground mines of the Sydney coalfield. Geological features such as paleo-sandstone river channels, seam splits, floor rolls, paleo-soils and stone-filled rupture features can rapidly alter the competency of immediate roof and floor strata, significantly reduce the height of the coal seam, cause rapid variations in seam gradient and influence the in situ and run-of-mine quality of the coal.The impact of these features on the over-all mining operation can be significantly reduced if mine management can be for-warned of their impending occurrence. Using the information acquired from boreholes, geological mapping, x-ray diffraction analyses, microscopic studies, geophysical logs and seismic surveys, sedimentary models have been constructed which enable the mine geologist to predict, with increasing accuracy, the future occurrence of deleterious geological features ahead of the working face."

Jan 1, 1986

By W. G. McBride

The mining industry has already become highly technical in all its branches and this has brought about specialization in mining engineering. Increasing demand for mineral products, exhaustion of high-grade or easily worked deposits, and narrowing of the fields for exploration and development, are forcing mines to greater depth and to working material of lower grade and more complex composition. The Robinson Deep at its Turf shaft has reached a depth of 7,640 feet and expects to go to 8,500 feet; Miami Copper, under normal market conditions, profitably mines ore running only 16 pounds of copper to the ton; Alaska Juneau is making a profit on ore running about $1.15 per ton in gold; and many mines are handling ores of an extremely complex nature. In each case, the success of these operations has depended upon the application of sound scientific principles and good business methods to the problems involved. It may be safely assumed that mining at great depth and the exploitation of low-grade, or complex, ores will become more and more important as time goes on, and this means that greater and greater demands will be made upon the technical skill and business ability of the mining engineer. To meet this condition, the more or less haphazard methods of training the young engineer that have prevailed in the past will have to be replaced by a careful and well-ordered system of engineer-training. Upon the industry and the older mining engineer falls the duty of providing means to assist the deserving student to prepare himself properly to meet the increased demands that are falling upon his profession. Consideration of the training of the mining engineer involves a decision as to what constitutes his field of usefulness. Technical control of methods and processes obviously falls upon the engineer, but there are still many who doubt his usefulness in the executive field, particularly in positions involving close contact with the men and work. Many engineers have failed as shift-boss or foreman, but this has been generally due to fault in the management in using men who were temperamentally unfit to lead others or who lacked the necessary preliminary training.

Jan 1, 1932

By Martin P. O'Connell

"IT IS INDEED A PRIVILEGE to address a group representing a sector of the Canadian economy so important as is the mining sector. Important, not only today, but certainly of great importance for the future development of Canada, for employment, for our trade balance and indeed, when one looks at what we are calling increasingly an industrial strategy, for the future. Surely mining will have a very significant role to play in fulfilling that. It's of special interest to me, as the Minister of Labour - and I ought to confess at the very beginning that I am just two months into this function - of special interest for me to know that you are giving such attention to labour-management relations. I think it is timely that, from my point of view at least, you do this, because for the first time in twenty four years major revisions of the Canada Labour Code as it relates to industrial relations and disputes settlements are currently in the House of Commons going through their second reading, after an easier introduction and some changes which I would be very pleased to describe later this morning. It is very timely too, I think, that we should be looking at this area because public interest is certainly at a high level. It is not only at a high level but it expresses a good deal of irritation with the current status and procedures and results in collective bargaining and there is some urgent search for more sophisticated or modified procedures for settling differences in labour-management relations. The public wants different kinds of results. I think that is apparent to all of us. They want results in terms of justice and equity on both sides. And it means that a Minister of Labour and certainly governments who often are representing, or are the third party in discussions, have a very important and complex role to play in attempting to create a balance as these two parties come to contracts and come to agreements."

Jan 1, 1972

By T. S. Grewal, S. C. Gupta, H. Natarajan, T. W. McQuade, N. Nejibulloev-Mamedov

Cigar Lake is one of the world’s largest high-grade uranium mines. The ore mined at Cigar Lake is milled at Orano Canada Inc’s (Orano) McClean Lake mill. The average Cigar Lake ore uranium grade since the start of mining activities in 2014 is 17.8% U (range 8– 28%). To achieve budgeted production of 18 M lbs U3O8/yr the required average feed tonnage to the mill is about 45 kt/yr. Arsenic, occurring as arsenides and sulpharsenides, is one of the major elements of concern associated with Cigar Lake ore. The leaching process is a sulphuric acid leach under oxidizing conditions at near atmospheric pressure. The presence of arsenic in the ore consumes oxidant in leaching as well as ferric sulphate in tailings preparation for arsenic sequestration. The average arsenic grade since the start of mining at Cigar Lake is 0.57% As. Further, the ore is hosted in a matrix of sandstone and clay, which results in poor settling in CCD. The average uranium grade for the balance of Cigar Lake Phase 1 ore is expected to drop to 12.5% U and the average arsenic grade is expected to increase to 1.6 % As, with an annual average peak of 2.5%. Therefore the tonnage throughput required to sustainably meet the production target will increase to 55 kt per year. Orano partnered with Hatch Ltd. (Hatch) to perform a gap analysis study to identify key circuits and equipment in the mill that would require debottlenecking. A METSIM mass balance model of the McClean Lake mill was generated and validated with actual mill operating data. Various feed scenarios were then studied, and the outcome was a traffic light table, which highlighted feed scenarios that exceeded installed capacity of major equipment and circuits. The results provided the basis for the PDC for the pre-feasibility study. This paper will outline the results of the gap analysis, the mass balance model, the feed scenarios and the study undertaken to prepare the McClean Lake mill for the change in ore quality from Cigar Lake.

Jan 1, 2020

By Michael S. Moats, Alex Luyima, Tomas Oliveira

Some commercial copper electrowinning facilities use Cyquest N-900 (a polyacrylamide) or HydroStar (a modified polysaccharide) to improve the density and smoothness of copper electrodeposits. However, the effects of these additives have not been studied extensively in the open literature. Thus, the electrodeposition of copper at 40 oC from a non-stirred synthetic electrowinning electrolyte (40 g/L Cu2+, 160 g/L H2SO4, and 20 mg/L Cl-) in the presence of various concentrations of either additive was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV results show that neither additive has much effect on the nucleation overpotential of copper electrodeposition on stainless steel. However, Cyquest N-900 polarized the copper deposition reaction upon the return sweep. The EIS data indicates that Cyquest N-900 increases the reaction’s charge transfer resistance and creates a second low frequency loop. HydroStar had minimal effect on the electrochemical data generated by CV or EIS. Thus, the mechanism by which HydroStar affects the copper deposition reaction still needs to be determined.

Jan 1, 2014

By G. Mihaylov

The basic principles of systems analysis are presented. A model has been designed to determine the location of the Main opening in the presence of three or more stock orebodies. The necessary condition is to find a location for the Collection point which is an essential element in opening up each orebody (stock). The model takes into account the total transportation costs from each orebody to the collection point. Three variants are considered provided that the orefield is divided into two levels at least: - a collection point is designed at every level; - a collection point is designed at the lowest level, i.e. where the so-called concentration level is formed; - the collection point is located at a point between the planes of the two levels; The effect of the depth of mining and mine output on determining the method of opening up the orefield has been analyzed by considering a vertical and/or an inclined shaft. A function has been constructed which allows for investigating in both a static and dynamic regime the capital costs for constructing the whole complex including the shaft. The character of the function does not allow finding the global limits. Therefore, it is of particular importance to specify the limiting conditions. In this case these are the flow capacity of development openings and the shaft. The basic groups of cost and natural indicators for assessing and selecting an optimal technological solution have been systematized. The combined analysis of the two approaches to finding the location of the Main opening and determining the mining method enables us to determine when an inclined shaft is best, and the depth at which opening by a vertical shaft has no alternative. Thus, a transition area is formed for which the selection of an optimal technological solution requires an analysis similar to that proposed in this paper. Conclusions are finally drawn which serve as a basis for determining the areas of application of each opening, including the use of a combined scheme of mine opening. The approach presented can be used in both investigating the possibilities for opening up new orefields and reconstructing existing ones in cases when the mining operations go deeper.

Aug 1, 2013

By H. A. Kee

In the mining industry, as in other business, one of the more satisfactory results of sincere but cheerful effort lies in the proper completion of undertakings and problems, which, to be successful, must continually hold the interest of all concerned in the work. In most undertakings, genuine interest and satisfaction is largely dependent on the proper appraisal of opportunities presented, and the opportunity to associate ourselves with sinking operations at McIntyre central shaft, from the surface to a depth of 4,133 feet, was genuinely appreciated. This opportunity was made possible by the previous persistent and successful leadership of Mr. J. P. Bickell, President, with the assistance of his associates, and of the general manager, Mr. R.J. Ennis, in the development of the McIntyre Porcupine mine, and I beg to state that any success in this sinking operation was very largely due to the congenial co-operation and splendid workmanship of Captain Martin C. Horne, his shift bosses, leaders, and all those who worked with us . Our slogan throughout was " Safety First for Pleasant and Efficient Workmanship," and this general policy made it possible to sink and timber 2.,123 feet during the first year without a serious accident.

Jan 1, 1928

By M. K. Gangal, A. E. Hall, S. B. V. Stewart

"An investigation into the problem of atmospheric fog in Canadian mines is described. Fog occurs in several mines and the reduced visibility can result in the closure of workings for safety reasons. Information on the mechanisms of fog formation are discussed and the methods for improving conditions are reviewed with their relative costs.INTRODUCTIONAtmospheric fog occurs in several Canadian mines during spring and summer. The fog which reduces visibility, contributes to loss of production and increased accident risk . Closure of ramps in mechanized mines causes mining to be stopped or rescheduled, and stoping and grade control may be affected . Increased corrosion of equipment may result from acidic fog .Fog is commonly caused by saturated air being compressed and heated by an inlet fan and then being circulated in an ascensional system with heat transfer to the walls of wet airways. This causes supersaturation and water droplets condense to create fog, with liquid water contents of 0.5 g/kg to 3 g/kg of air. These concentrations reduce visibility to less than 10m and prevent mining. Less severe fog is usually tolerated as a nuisance, about which little can be done."

Jan 1, 1989

By W. T. Irvine

"The H.B. Mine, a zinc-lead operation of the Consolidated Mining and Smelting Company of Canada Limited (Cominco), is in south central British Columbia, on Sheep Creek, a west-flowing branch of the Salmon River. It is 3 miles by road from B.C. highway No. 6, 30 miles south of Nelson, B.C., with an excellent highway connection to the smelter city of Trail, 35 miles from the mine. The nearest permanent settlement is the village of Salmo, 7 miles distant by road. The mine is situated along a belt containing other important zinc-lead deposits, including those of the Canadian Exploration Company, 3 miles to the south, and the Reeves MacDonald mine, 9 miles distant again to the southwest.Deeply oxidized outcrops were located in 1907 on the north side of Sheep Creek valley by two prospectors named Horton and Benson. The property was given the name H.B., after the two discoverers, and there commenced a long and intermittent series of mining operations designed mainly to develop and extract oxidized lead-zinc ore. In 1925 a determined attempt was made by a British syndicate to develop a large tonnage of sulphide ore, but this ended in failure after some 3,000 feet of lateral development had been done. In 1927 Cominco acquired the mine, but it lay idle until 1946 when a geological study was followed by a program of surface drilling which encountered extensive sulphide mineralization. An underground development program revealed more details of the deposit, and sufficient ore was found to warrant construction of a 1,000-ton mill. Mine preparation and mill construction were completed by early 1953, but production was deferred due to low metal prices. The mine was finally brought into production early in 1955."

Jan 1, 1949

By J. J. Ferreira, M. L. Thurston, I. L. Chinn, D. M. Rose

"Concerns about using microdiamonds for resource estimation have been raised by workers because multiple diamond populations exist in many parts of the mantle source region, small diamonds in kimberlite could be exposed to proportionately greater levels of resorption and modification, and euhedral microdiamonds could crystallize immediately prior to kimberlite eruption. This paper addresses these concerns; discusses the geology of the mantle, the principal diamond host rocks, and the impact of mantle processes; compares micro- and macrodiamond properties and features; and outlines steps to identify and mitigate the risk of diamond resorption and its impact on the diamond grade-size relationship.RÉSUMÉ Des travailleurs se sont interrogés sur l’utilisation de microdiamants pour estimer la ressource; en effet, de multiples populations de diamants existent dans plusieurs secteurs de la région source dans le manteau. Des petits diamants dans la kimberlite pourraient être exposés à des niveaux proportionnellement supérieurs de résorption et de modification; de plus, des diamants idiomorphes pourraient cristalliser immédiatement avant l’éruption de la kimberlite. Le présent article traite de ces questions, discute de la géologie du manteau, des principales roches-mères des diamants et de l’impact des processus dans le manteau, compare les propriétés et les caractéristiques des micro- et des macrodiamants et définit les étapes pour identifier et mitiger le risque de résorption des diamants et son impact sur la relation entre la taille et la qualité des diamants."

Jan 1, 2016

By Charles Tkaczuk

In order to remain competitive the mining industry must keep up with changes in technology. Many innovative technologies from the mining perspective are commonplace in other industries. A ?Global? review of technologies will often reveal existing technologies that can be innovatively applied in the mining industry. Industries, which are rife with proven solutions include, medicine, biotechnology, security, manufacturing, telecommunications, etc. This paper addresses the communications aspect of mining where greater productivity, lower costs and the ability to quickly react to mining related events is obtained through an increase in remote monitoring and operating control. A review of the communications systems in place globally reveals technologies that, with minimal modification, can be immediately applied to the mining environment. We discuss the concept, advantages and implementation of existing communications technology from an industry that is not usually associated with the mining industry. This technology will form the basis of a solid platform on which can be built a state-of-the-art process monitoring, control, and communication system. This lays the groundwork for providing one solution to the underground mining industry?s most difficult problem, establishing a reliable, maintainable and cost-effective underground bi-directional wired/wireless data, video and analog communications system. We need look no further than our own doorsteps to find such a solution. The cable that you see coming from the simple green or brown box on the boulevard into your home contains hundreds of television broadcast channels, FM radio channels and data channels. And if you have a set-top box, you are in control of it all. The Cable Television Broadcast Distribution System suppliers of today are at the leading edge of converging all the different methods of communications onto a common carrier, coaxial cable or fibre optic cable. There is no fundamental difference between providing a reliable communications network to a city/neighbourhood/home/personal computer than there is to a mining operation/underground level/equipment or person. The principle is the same. Only the application is different. Realizing this, we can capitalize on the efforts of other industrial sectors, to solve our communications problem. Where else can you find a solution to a problem that is mature, having been developed with the input of thousands of engineers, and having hundreds of millions of dollars spent on research and development, manufacturing, distribution, global presence and engineering support?

May 1, 2003

By Georgy A. Cherkashov, Andrey V. Efimov, Yury S. Borodaev, Nadezhda N. Mozgova, Sergey G. Krasnov, Tamara V. Stepanova, Alexander M. Ashadze

"Abstract - A horizontal mineralogical-geochemical ore zonation with a southeast to northwest trending succession of Cu and Fe (Zn) main zones has been discovered in the Logatchev hydrothermal field (14°45??N Mid-Atlantic Ridge). The major minerals are pyrite, chalcopyrite, bornite, isocubanite, digenite and chalcocite. Zn-sulfide, marcasite and covellite are less abundant. Rare minerals are native copper, zincian copper and cobalt pentlandite (first found in oceanic massive sulfides), Cu and Cu-Co-bearing Fe-disulfides. Two groups of the main sulfide assemblages with different copper contents are recognized: Group I comprises assemblages with primary sulfides (isocubanite, chalcopyrite, pyrite and Zn-sulfide; Cu up to 35 wt% in Cu-bearing minerals); Group II contains assemblages with secondary Cu-rich sulfides (bornite, digenite, chalcocite; Cu ~60 wt%) as well as rare minerals (cobalt pentlandite, native copper and zincian copper). The assemblages of Group I formed at a temperature of about 300°C; the sulfur fugacity (log fs2 atm) at 300°C is probably 9.9. Relations between minerals of this group are contradictory, attributed to non-equilibrium environments, and no unified sequence of crystallization of minerals has been determined. Minerals of Group II replace, rim or cross the assemblages of Group I. Group II minerals crystallized in a distinct sequence (cobalt pentlandite-bornite-digenite- chalcocite-native copper), with increasing copper content from the start to the end of the depositional sequence. This may correspond to pH from 7 to 8 near Eh = -0.2 at 250°C. Minerals of this group were generally formed under hypergene alteration processes. Compositions of ore minerals were studied by means of electron microprobe analysis (EMPA) (150 analyses). Narrow composition fields were revealed in all main sulfides, which comprised known experimental data. ZnS contains 6.0 to 28.0 mol.% FeS, which is close to data known for other hydrothermal massive sulfides from the Mid-Atlantic Ridge (MAR). A common admixture in ZnS is Cu (0.16 to 1.32 wt%). Rare grains of unusual anisotropic Fe-disulfides, (Fe0.95Cu0.05)S2 and Cu(Fe,Co)9S20, were found among the ore minerals."

Jan 1, 1999