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By E. P. Wiechrnann, C. M. Castro, G. A. Vidal

In copper Eta plants the optimal current density setpoint depends on the electrolyte composition and temperature. However, conventional plants operate with large standard deviations. A value of 14% with current densities offsets up to ±50% is typical. For worst, during opencircuit or shortcircuit events this variation can be from -100% to +200%. Naturally, energy consumption and copper quality are compromised. Several devices have been successfully employed to reduce set point deviations. Last developments include; Optibar Segmented Intercell Bars, Outotec Electrodes Arranging Method and NTC Selective Electrodeposition Enhancers. This paper researches and compares these technologies. It is shown that short circuits can be effectively reduced in occurrence and magnitude. Moreover, 95% of the electrodes can be forced to operate within ±10% of the set point. The specific energy consumption is reduced from 2,000 KW per Ton to values close to 1,900 KW per Ton.

Jan 1, 2011

By M. Sanchez

In the last decades, the Chilean copper mining and metallurgical industry have had to modify their technological processes to meet the environmental regulations implemented by the Chilean government, and also to support the pressure of the public opinion. Thus, air quality standards for sulfur dioxide and particulate matter (primary and secondary), plans for reducing emission of arsenic by the Chilean copper smelters, effluents discharge limits, among others regulations were applied by the environmental agency. Additionally, agreements on cleaner production were carried out by mining sector and government. Now, a draft law on mine closure, and another on environmental mining wastes (abandoned mines) are being discussed by the authorities and the mining sector. In the context, production and environmental impacts in different ways to produce copper in the Chilean mining industry are reviewed and regulatory tendencies as well as abatement technologies today used are exposed and discussed in this presentation. Pyro, hydro and electrometallurgical processes employed and their current effluent and contaminants are presented showing various alternatives of treatment in the copper industry. An update of regulations established in Chile vis a vis copper production, with an especial attention to mine closure are also presented.

Jan 1, 2007

By J. W. Merks

"Simulation is the process of designing a computerized model, of a system or procedure, for the purpose of understanding its behaviour and developing strategies to control its operation. Simulation models are rapidly becoming an effective tool for mineral processing plants. Powerful software and fast hardware are more readily available than a basic understanding of the theory of mathematical probability and applied statistics that process simulation models demand.Simple spreadsheet software can be used to develop simulation models that take into account any set of conditions at a mineral processing plant. In addition to an unbiased estimate for each variable in the set on which two-and three-product formulas are based, reliable variance estimates for all variables are required. How to estimate variances, effectively and at the lowest possible cost, and how to compute variances for simple functions such as the metal content of a quantity of ore or concentrate, or more complex functions such as the percentage recovery at a mineral processing plant, are the key to useful simulation models.IntroductionSimulation models for systems and procedures have become one of the most powerful and effective applications for computers( 2.6). Simulations are applied to a wide range of scientific and engineering disciplines. Generally, a model is designed to investigate the effects of changes in and interactions between a set of variables before a system is in operation or a procedure is implemented, by simulating weeks, months, and even years of operation, in a few minutes of computer time. Along with practical and useful applications always comeabuse and misuse. For a simulation process cannot be more reliable than the methodology that was applied to design the model, to estimate variables and variances, to check performance, and to verify validity. A mineral processing plant is a dynamic system that changes continuously as a function of time but within probabilistic constraints that can be estimated by applying statistical tools and techniques to the variables and variances that interact in the system.A model should be designed to simulate not only the set of variables but also the variance for each variable. Models in which constant variances are used to generate normally distributed random numbers, are less realistic than models in which the variances are simulated first, and then used to simulate the variables."

Jan 1, 1991

By D. Beneteau, D. Milne

"Advances in technology provide educators with valuable tools to enhance their teaching and efficiently deliver content to larger audiences. University educators are often encouraged to become more “research intensive” and to increase student enrollment. Faced with these pressures, there is a tendency to use technology to improve teaching efficiencies rather than to enhance existing teaching approaches. Practical learning in applied engineering courses would suffer greatly if hands-on experience is not emphasized. This paper discusses advantages and limitations of new technologies applied to learning, and methods to incorporate more hands-on experiential teaching techniques to applied mining engineering courses.RÉSUMÉ Les avancées technologiques fournissent aux éducateurs des outils intéressants pour rehausser leur enseignement et livrer efficacement de la matière à de grands auditoires. Les éducateurs universitaires sont souvent encouragés à devenir plus « axés sur la recherche » et d’augmenter l’inscription d’étudiants. Face à ces pressions, il y a une tendance à utiliser la technologie pour améliorer l’efficacité d’enseignement plutôt que de rehausser les approches existantes d’enseignement. L’apprentissage concret dans les cours d’ingénierie appliquée souffrirait grandement si l’accent n’est pas mis sur l’expérience pratique. Le présent article discute des avantages et des limitations des nouvelles technologies appliquées à l’apprentissage et des méthodes pour incorporer plus de techniques expérimentales pratiques aux cours de génie minier appliqué."

Jan 1, 2016

By M. B. Myers

The subject matter of this paper will be discussed under three main headings. 1.-Fire-Resistant Fluids: (a) the need for such materials, based on historical events; (b) a definition of fire -resistant fluids; (c) general description, characteristics, operational parameters, advantages and disadvantages of oil-in-water emulsions (HFB), water-polymer fluids (HFC) and anhydrous or synthetic fluids (HFD). 2.-A review of equipment associated with the use of fire-resistant hydraulic fluids; (a) performance testing of hydraulic equipment, i.e. gear pumps, vane pumps, axial and radial piston pumps, hydraulic motors, etc., pressure, speed, filtration limitations, etc., and effects on valves, elastomers, paints, etc.; (b) hydraulic system design features and selection of suitable units; (c) types of mining applications currently employing fire-resistant fluids. 3.-Test methods used to evaluate fire-resistant fluids: (a) fire testing methods, i.e. wick tests, spray ignition testing, hot manifold tests, factory mutual tests, all to establish fire-resistancy parameters and acceptance; (b) new developments in fire-resistancy evaluation; (c) the examination of other performance tests, e.g., effects of evaporation, sliding wear, life of rolling element bearings, etc.

Jan 1, 1979

By Harry Jomini

Introduction The Wakefield plant of the Aluminum Company of Canada, Limited - a member of the Aluminum, Limited, group of companies - produces magnesia, magnesia fertilizer ingredient, and hydrated lime, from brucitic limestone. Wakefield is on the Gatineau river in Wakefield township, Quebec, some 22 miles north of Ottawa. The plant is near the western bank of the river adjacent to the Ottawa-Maniwaki highway and branch line of the Canadian Pacific railway. The plant is unique in the sense that it is the only place in Canada where brucite is processed. It is also distinguished for its outstanding safety record, as not a single lost-time accident occurred during either 1948 or 1949. The plant is amply provided with safety and comfort provisions in keeping with the standard practice in all of the twelve plants operated in Canada by Alcan and its associated companies. History Following the identification of brucite in the Rutherglen and Bryson districts in Ontario, occurrences of the mineral were discovered in the Wakefield area, Quebec, in 1939. After exploratory work on these deposits and investigation by the Bureau of Mines, Ottawa, on a method of extracting the brucite from the ore, a plant for treating the ore from the Maxwell property was built in 1941 by the Aluminum Company of Canada and commenced operations in early 1942. The process used is more or less in accordance with the method worked out by Mr. M. F. Goudge of the Bureau of Mines.

Jan 1, 1950

By J. Mrozowski, R. Kurowski, A. Chmielarz, Z. Szolomicki

PbSO4 is a commonly encountered component of the materials used in lead recycling (e.g. battery paste) and in by-products of metallurgical processes (e.g. residues from zinc hydrometallurgy, dust from copper smelting). Smelting of battery paste results in SO2 emission and in generation of significant amounts of hazardous ‘white slag’. Those adverse phenomena can be eliminated by removal of sulphur from the paste. Lead-bearing by-product materials are of polymetallic character with usually low Pb content, which makes lead recovery technologically difficult and uneconomic. However it can be successfully achieved by extraction of lead sulphate from solid phase with triethylenetetramine (TETA) water solutions. That compound has capability for selective solvation of a whole lead sulphate molecule. Virtually pure lead carbonate can be precipitated by means of saturation of lead-loaded aqueous TETA solution with carbon dioxide, and complete regeneration of the extractant is achieved by fixing of sulphate ion into gypsum through operation of calcium hydroxide suspension. The paper presents results of the lab and pilot scale studies into process of battery paste desulphurisation and recovery of lead from the residue of zinc calcine leaching.

Jan 1, 2014

By M. Tadayonsaidi

The effect of alloying elements on the mechanical properties and thermal expansion of 336 casting alloy usually used as piston alloy which has low thermal expansion and very good high-temperature mechanical properties and good wear resistance was investigated. The mechanical properties and thermal expansion characteristic of samples with different combination of alloying elements, which enhance to reduce the cost of products, have been studies, The results show remarkable increase in the mechanical properties with increasing the amount of Cu and Mg, while are reduced with increasing amount of Ni, On the other hand, the use of eutectic aluminum alloy as 336 alloy with higher percent of Cu and Mg and lower percent of Ni are recommended for industry, due to economical viewpoint and satisfactory properties.

Jan 1, 2005

By G. Capobianco

"The coal industry is an important part of Canada's economy - as an energy source, employer, and generator of export earnings. Coal comprises 71% of our fossil energy and with rapidly advancing handling and burning technology will clearly play a major role in our national energy mix, eventually as synthetic gases and liquids.International coal markets are very competitive and Canada is disadvantaged by long rail hauls to port, and a heavy tax burden. However, high mine productivity has allowed us to increase our markets.Currently, domestic markets are dominated by coal use for electrical generation, a market with significant growth opportunities.Strong growth is expected in export thermal markets, while metallurgical coal demand is projected to show little or no growth in the medium term. IntroductionThe coal industry is a vital part of the Canadian energy scene .• Coal supplies 17% of Canada's energy.• On a per capita basis, Albertans use more energy in the form of coal than they do oil and gas.• The value of Canada's exports of coal last year was equal in value to all the cars we imported from Japan.• Coal is our largest single export to our seco nd largest trading partner, Japan.• The value of coal produced in Canada exceeds the value of any other single mineral produced in thi s country.• In Alberta, the safety record for coal mines is on a par with that of department store clerks.• The coal industry employs about 25% of the total number of people employed in all metal mines in Canada, directly and indirectly accounting for about 50 000 jobs.Coal comprises 71% of Canada' s hydrocarbon energy resources on a crude oil equivalent basis . This is more than double our oil sands resource and dwarfs our conventional crude oil and gas resources (Fig. I). In the short term, coal as a solid fuel plays a significant part in the Canadian energy scene. In the longer term, coal, in the form of electricity and eventually liquids and gases, has a tremendous role to play. In 1986, Canada produced 57.8 million tonnes, slightly down from the record high of 60.8 million tonnes in 1985. Our exports in 1986 were 26.0 million tonnes, a growth of 53% in three years."

Jan 1, 1988

By D. Mas Ivars, K. Suzuki, J. A. Vallejos

"A comprehensive geotechnical characterization has been undertaken at the El Teniente mine to describe and determine the rock mass behaviour strength properties of the primary copper ore. The Synthetic Rock Mass (SRM) modelling approach is used to simulate the mechanical behaviour of this heavily and unfractured rock mass. The micro-parameters of the model have been calibrated against mechanical properties and scaling laws for intact rock and veins, in order to represent virtual samples of four different geotechnical units. Results can be used to predict the rock mass scale effects, anisotropy, and brittleness properties that cannot be obtained using empirical methods.INTRODUCTIONThe primary copper ore at the El Teniente mine is described as very competent and massive, given that it exhibits a brittle behaviour (Rojas, Cavieres, Dunlop, & Gaete, 2000). This description is coherent with the geological description of the rock mass, which does not have discontinuities match as the definition provided by International Society of Rock Mechanics (ISRM, 1981). Only faults can be classified as discontinuities, but they are widely spaced. The primary copper ore has a high frequency of veins, where the cooper mineralization is hosted, these vein network structures are known as stockwork. Soft veins containing weak minerals as infill (chalcopyrite and anhydrite) control the disassembling of the rock mass during caving (Brzovic & Villaescusa, 2007).Presently, there are mainly two traditional methods used to estimate the strength of the rock mass: 1) determination of the strength envelope of the rock mass using scaling parameters from laboratory tests and 2) using numerical modelling based on back analysis of previous experiences of failure observed and measured in mining or civil excavations. The primary copper ore of El Teniente mine has no fractures; therefore, it is difficult to determine a rating that would enable to scale laboratory data, such as, RMR (Laubscher, 1977) or GSI (Hoek, 1994). This is the reason why the first option is not valid unless the entry data is manipulated or adjusted in order to obtain reasonable results. The second option requires, in general, a good characterization of a previous failure event in the rock mass, which is not always available. In recent years, new techniques of numerical modeling have been developed (PFC3D, ELFEN, Abaqus). Those methodologies are the third way to estimate the strength of the rock mass, but they are still in development. Particularly, the concept of SRM developed by Itasca is implemented in this study (Pierce, Mas Ivars, Cundall, & Potyondy, 2007; Mas Ivars et al., 2011), aiming to capture the real behaviour of the rock mass."

Jan 1, 2015

By C. Klinkenberg, G. Zhu, K. Hulka, S. V. Subramanian

A quantitative model based on strain accumulation in multi-pass rolling is developed to overcome a large critical strain for dynamic recrystallisation in a Nb microalloyed steel with high Mn content (HTP steel). The larger the critical strain for dynamic recrystallisation, the finer is the dynamically recrystallised grain size. The initial mill trial showed that it is feasible to achieve ultra-fine grain size by dynamic recrystallisation but the prevention of static recrystallisation in between passes is identified as an essential condition to suppress mixed grain size. The data-base on static softening kinetics at short interpass time was experimentally determined on WUMSI and incorporated in the model. The model is used to optimise the strip rolling schedule to prevent static recrystallisation in the interpass time. The rolling simulation of strip rolling schedule has validated the model prediction that it is possible to obtain a uniform ultra-fine ferrite grain size of about 1-2 micrometer diameter in final ferrite microstructure for industrial rolling parameters. A user friendly software package has been developed to apply the model for off-line control of mill processing parameters, i.e., time-temperature-deformation schedule of finish rolling in order to accumulate large strain to overcome a large critical strain for dynamic recrystallisation. The model is a powerful predictive tool for grain size control in multi-pass rolling.

Jan 1, 2004

By Guojun Wang, Zejun Chen, Wenchang Liu

Al/Mg/Ti laminated metal composite sheet (LMCS) can combine the merits of each of metal components, and obtain excellent performances. It incorporates the advantages of high strength, light weight, easy melt and atomization, and good space adaptability to substitute for the bumper Al sheet of Whipple shield structure for space debris shield. The Al/Mg/Ti LMCS was fabricated by hot roll bonding technology in a certain sequence. The manufacturing process and parameters were analyzed and studied, including the first rolling reduction, roll boding temperature and stacking structure of each metal. The microstructure of dissimilar metals and bonding interface were characterized and analyzed. The optimized manufacturing procedures and parameters were presented based on the microstructure and mechanical properties of LMCS. The research results offer some guides and references for controlling the shape of bonding interface, optimizing the annealing process, improving the mechanical properties of Al/Mg/Ti LMCS.

Jan 1, 2015

By G. J. Kipouros, W. Judge

"The prevalent metal extraction processes for most reactive metals are fused salt electrolysis and metallothermic reduction. The feed material for both of these processes is the anhydrous chloride of the metal under consideration. Dehydration of the feed material is then a critical step in the production of most reactive metals and requires rigorous thermodynamic analysis. Thermodynamic data for most of the reactive metal chloride hydrates have not been measured. Improper dehydration of the metal chloride may lead to a prohibitive amount of hydroxychloride, oxychloride, and oxide. To prevent hydrolysis a certain pressure of hydrogen chloride is required. An estimation and prediction model is presented for the vapour pressures of reactive metal chloride hydrates in an attempt to deduce the conditions necessary for dehydration to proceed without hydrolysis. Thermodynamic data including heat capacities, standard entropies, and standard enthalpies are estimated/predicted for all conceivable intermediate hydrate compounds. Estimations are based on published data as well as trends proven in similar systems. The thermodynamic estimations and predictions are presented for the magnesium, neodymium, praseodymium, and dysprosium chloride hydrates. INTRODUCTIONThe high reactivity of metals such as the alkalis, alkaline earths, and lanthanides prevents their reduction by traditional pyro- or hydrometallurgy. In their elemental form, these metals are raw materials in the manufacture of intermediate products such as alloys and electronic components. Currently the only two viable metal production methods are fused salt electrolysis and metallothermic reduction. Various feed materials have been proposed for these processes. Using the chloride of the metal as a feed material offers advantages in separation and purity of the final product, as well as lower energy input. Chlorides, however, are hygroscopic and must be dehydrated before use. Improper dehydration will lead to a prohibitive amount of oxychloride which will lower efficiencies and contaminate the final product.Optimum conditions for proper dehydration of MgCl2•6H2O to produce pure MgCl2 without hydrolysis have been calculated from existent thermodynamic data and have been reported previously (Kipouros, 1987; 2001). Calculations were also performed for the case of production of pure anhydrous NdCl3 from NdCl3•6H2O (Roy, 1997)] and the mechanism of dehydration was elucidated. Some thermodynamic studies on the dehydration of chlorides of the rare earths have also been conducted (Sundstrom, 1997; Hong, 1997; Aschcroft, 1968; Haeseler, 1965; Ukraintseya, 1989)."

Jan 1, 2012

"In a continuing investigation into the development of uranium alloys for armament applications, some complex base alloy corn positions were modified by varying the amount of alloying elements and by removing one or two of the alloying elements in turn from the base alloys. These uranium-base alloys were specially formulated in a search for heat-treatable, high-strength, ductile, high-density alloys. All alloys studied were ternary, quaternary or more complex alloys of uranium with molybdenum, zirconium, niobium and vanadium. Each cast alloy was studied under three different heat-treatments, and its mechanical and corrosion properties were determined. It was found that although most of the alloys studied had the hardness and strength required, they were extremely brittle and notch-sensitive under tensile stresses."

Jan 1, 1968

By Herbert D. Drechsler, James B. Stephenson

"AbstractThe paper identifies the major components of price change which affect the determination of the internal rate of return of a mining project. It illustrates several price indexes which may be used to measure general price increases, identifying techniques which might incorporate them into mine valuation procedures. The ""hurdle rate"" for new investment is discussed.IntroductionDECISIONS regarding the value of an orebody and whether or when to mine an orebody are based on an estimate of the cash flows which would be associated with its exploitation. These pro-forma cash flows represent cash in or out of a possible mineable deposit and include exploration and construction costs, sales revenues, operating expenses, taxes, debt borrowings, interest and debt repayment. It has long been recognized that when combining the cash flows occurring over the life of the mine, dollars received or paid out early have greater value than those received or paid out later. This time value of money has been incorporated into mine evaluation calculations through the use of present-value or discounting techniques. Another factor affecting mine valuation, inflation, is not accounted for by valuation techniques now in use. In recent years, price changes have become more volatile. In the past, price change could easily be ignored when evaluating potential mines. Today, the combination of larger investments and greater price volatility leads to great concern about the effects of price change on mine valuation."

Jan 1, 1977

By R. C. Gilmore

Underground longwall coal mining sections may develop explosive mixtures of methane-air in the mined-out gobs. If the panel are operated as bleederless or sealed gobs, progressive sealing along the gate roads as the longwall face retreats limits the flow of fresh air into the gob and thus deprives potentially explosive atmospheres of oxygen. In a project sponsored by the National Institute for Occupational Safety and Health (NIOSH), researchers at the Colorado School of Mines have used computational fluid dynamics (CFD) modelling to simulate the flow of gases in longwall gobs. Modelling indicates that targeted injection of nitrogen through the seals along the gate roads inbye the face can be used to control the size and location of methane and air clouds within the gob and to minimize or eliminate the explosion hazard resulting from the formation of flammable methane-air mixtures in longwall gobs.

Aug 1, 2013

By D. M. Muir

The mineralogy of residues formed during the pressure acid leaching of arid region nickel laterite ore varies according to the salinity of the process water, alkali cation additives and the overall acid loading. In fresh water, hematite is the main iron-bearing leach residue component, together with amorphous silica and hydronium or sodium alunite/jarosite [(H3O,Na)(Fe,Al)3(SO4)2(OH)6]. As the process water salinity increases, or as NH4+ or K salts are added, alunite/jarosite is the kinetically favoured iron-bearing phase accompanied by an increase in acid consumption. The alunite/jarosite appears as two XRD distinct phases with different Fe:Al molar ratios. In weakly saline water, iron-rich alunite/jarosite slowly transforms to hematite and an aluminium-rich alunite/jarosite together with the release of acid. The addition of potassium salts forms a more stable alunite/jarosite whilst the addition of ammonium salts leads to greater transformation of alunite/jarosite at 250°C. Weakly saline process water gives enhanced nickel recoveries, whilst strongly saline process water gives lower nickel recoveries but higher soluble iron because of chloro-complexation. SEM and microprobe analysis shows very little nickel is associated with the alunite/jarosite and hematite phases. Nickel losses to the residues are attributed to adsorption on amorphous silica and to a lesser extent on alunite/jarosite.

Jan 1, 2006

By J. Kalynchuk, R. Poulin, R. Pakalnis, D. Peterson

"A market survey of all underground mines in Canada (Fig. 1) was completed to determine the ex1ent to which cable bolts are being used as ground support. One hundred and nine questionnaires were distributed with 65% of them being returned completed. As a result, the quantity, types and locations of cable bolt installations have been determined. In addition, the grout pumps used, time required and cost of installations have been addressed. The popularity of other support types used in underground mines is summarized.IntroductionRock reinforcement consists of installing support within the rock mass (internal) or within the excavation (external). Within the past twenty-five years several new types of ground support have been introduced within the mining industry. Cable bolts were first introduced to the Canadian mining industry in the 19605 (Gramoli, 1975).Cable bolts have gained increased acceptance as a method of ground support during the past decade. The cable bolt is comprised of one central wire surrounded by six slightly smaller outside wires and typically having an over-all diameter of 15.2 nun to 15.9 nun (0.6 in. to 0.625 in.). The cable wires are made from high-strength steel with an ultimate strength of 26 tonnes (58 000 Ibs) (Goris, 1990). Current cable bolting practice consists of cement grouting one or more steel cables within a drill hole in order to reinforce the surrounding rock mass. Cable bolts are a form of internal support and are generally used in open stoping and cut-and-fill mining methods (Fig. 2).They can be either tensioned (active support) or untensioned (passive support) and may be of any length, though for underground mining applications, they are generally less than 20 m (65.5 ft) and are untensioned. A major advantage compared to previously used ground support is that the cables are flexible and can be coiled to approximately 1 m (3.3 ft) diameter coils allowing relatively long support to be installed in areas with limited head room (1.8 m).With the advent of bulk mining methods which require comparatively large stopes, it has necessitated the use of relatively long support tendons to stabilize the large spans being created. As a result, the use of cable bolts for ground support in mines has increased significantly within the past decade."

Jan 1, 1995

By Fred Horne

1N THIS PAPER, the writer proposes to limit his comments to few generalized phases of the subject, based on his personal experience in the midwestern United 'States and in one section .of the Coal Branch in Western Alberta. The following statistics are submitted to show the importance that strip mining has assumed in the coal mining industry of the United States. In 1914, 1,281,000 tons of strip coal were produced, amounting to 0.3 per cent of the total production. In 1948, the total was 13~,505,000 tons, representing 23.3 per cent. In 1949, the percentage figure dropped slightly and this can be partially accounted for by the labour disturbances prevalent throughout the year. In 1914, there were 48 power shovels and draglines being used in the stripping of coal; in 1949 there were 3,712, not to mention other types of coal stripping equipment such as bulldozers, tractors and scrapers, rotary excavators, and stackers. At the bituminous coal mines in Western Canada, strip mining was introduced only a few years ago, two of the major reasons for its development being the need for increased production during the war and post-war years and the need to hold the line on increasing production costs, but even in these few years the percentage of strip production has in-creased to such an extent that some mines that, five or six years ago, were producing all their tonnage from underground operations are today obtaining up to 80 per cent of their total output from strip mines.

Jan 1, 1951

By C R. Crook

A brief outline of production methods and processes is given to show how maintenance fits into the picture at this plant. The work force, and the tools needed to carry out this function, are then described. Preventive maintenance practices, scheduled annual shutdowns and routine check-downs are explained, especially as related to planning and to the materials and labour involved for a mini-mum downtime. A brief explanation of the materials, sup-plies and spare parts program, as well as the part played by the Stores Department in conjunction with the Maintenance Department, is given. Cost control and equipment expenditure indicators are explained. Some specific examples of maintenance jobs are described in order to show the flexibility of the program. S HERRITT GORDON Mines Limited has been in continuous production, except for the planned downtimes needed for expansion tie-ins, or the annual shutdown check-over periods, since the first shipment of nickel on a commercial basis in July of 1954.

Jan 1, 1964