Search Documents

By L. D. Jaffe, M. R. Norton, J. H. Hollomon

In the practical heat-treatment of steel the decomposition of austenite usually occurs during cooling rather than at constant temperature. Nevertheless, the course of this decomposition has generally been studied only isothermally. Isothermal studies are not only simpler experimentally, but have the great theoretical advantage that one of the variables, temperature, is constant. It is the purpose of this paper to outline the principles that govern the relations between isothermal and anisothermalt‡ decomposition of austenite, to present and systematize the available experimental information, and to indicate the gaps in the existing knowledge. Some of the experimental information is the result of new work.§ Most of it is derived from scattered data in the literature. Many of these data were obtained incidentally in the course of research on other subjects and their significance has not been pointed out and perhaps not understood. It is hoped that this paper will aid future planning of more extensive research on anisothermal decomposition. Method In order to study the relations between isothermal and anisothermal decomposition, it appears fruitful to view anisothermal decomposition as taking place at a series of constant temperatures1 (except for the martensite reaction, which does not occur isothermally to an appreciable extent). When the time the steel is at each temperature is finite, the over-all amount of the reaction is considered to be the sum of the amounts occurring at each of the successive temperatures. During continuous cooling or heating, the time the steel is at each temperature and the difference between successive temperatures can be considered to approach zero. The over-all amount of transformation will then be given by integration over the range of temperatures involved. This point of view is advantageous in that it considers anisothermal transformation to be a series of isothermal transformations. The problem thus becomes one of determining the effect of partial decomposition at any given temperature upon subsequent decomposition at another temperature. Single Anisothermal Reaction Consider a phase brought to a temperature at which it is unstable, held there until it has partially transformed, and then brought to another temperature at

Jan 1, 1947

By Borje Bjorkvall

At LKAB's plants in Lappland, Sweden, sintered pellets are manu-factured according to three different industrial processes, viz. shaft furnace at Malmberget, straight-grate at Kiruna and grate-kiln at Svappavaara. At present the total annual capacity amounts to 4.7 million tons. However, since it has been decided to erect a new straight-grate plant (2.5 million tons) at Malmberget, and because of the decision to extend and rebuild the existing plants, it is estimated that the annual capacity will be increased to somewhat over 8 million tons by 1973. The great majority of the pellets produced is exported. They are thus reloaded several times and generally speaking roughly handled, resulting in larger or smaller product losses on arrival at the point of use. It is there-fore of great economical interest to have a good control over the transport strength of the pellets by appropriate quality testing at the point of production. In addition to good transport strength, further demands are ob-viously made on pellets destined for blast furnace operation. The blast furnace burden must maintain a good permeability for the gas. The pellets must thus have a favourable size distribution and must not be so weakened by reduction that they disintegrate under the stresses and clog the blast furnace shaft. Furthermore, the burden must have good reducibility. An increase of the rate of reduction can obviously mean increased blast furnace capacity and reduced coke consumption. In order to optimise the properties of the pellets in these respects, the producer must also be thoroughly familiar with their behaviour during reduction, particularly as the customer's interest in the reduction properties of the pellets' has increased over the last few years. Up to now the only quality demands the customer has made have generally had to do with the cold strength and the screen analysis. Thus a quality control of in addition to good transport strength, further demands are obviously made on pellets destined for blast furnace operation. The blast furnace burden must maintain a good permeability for the gas. The pellets must thus have a favourable size distribution and must not be so weakened by reduction that they disintegrate under the stresses and clog the blast furnace shaft. Furthermore, the burden must have good reducibility. An increase of the rate of reduction can obviously mean increased blast furnace capacity and reduced coke consumption. In order to optimise the properties of the pellets in these respects, the producer must also be thoroughly familiar with their behaviour during reduction, particularly as the customer's interest in the reduction properties of the pellets' has increased over the last few years. Up to now the only quality demands the customer has made have generally had to do with the cold strength and the screen analysis. Thus a quality control of

Jan 1, 1972

By George B. Lee

During the two years in which the new reduction-works of the Copper Queen Consolidated Mining Co. have been in operation at Douglas, Ariz., there has developed a remarkable condition in regard to the corrosive action of the water used to cool the jackets of the blast-furnaces. Were it not for the many contradictory features, it might pass as one of the unavoidable troubles due to the composition of the water. This water, obtained from wells 600 ft. deep, is also used in the steam-boilers, and its composition, as shown by the following analysis, does not indicate the presence of any ingredient which would explain the corrosion: Grains Per U. S. Gal. Silica,...........0.861 Iron oxide and alumina,....... 0.223 Calcium carbonate,....... 0.261 Calcium sulphate,................. Magnesium carbonate,........... Sodium and potassium sulphates,..14.850 Sodium and potassium chlorides,.9.732 Sodium and potassium carbonate, . 6.482 32.409 The jackets are made of inner plates 0.5 in. thick and an outer plate # in. thick, with 3/8-in. stiffeners between the inner and outer plates. In from 10 to 12 months the inner plates have been reduced by corrosion to a thickness of from + to & in., while the outer plate in the same time is reduced by less than 1/16 in., and the stiffeners show very little corrosion. The plates are pitted and eaten away in some places more than in others. There is practically no scale found on the jackets, but when cleaned considerable iron oxide is found in the bottoms. With an action so marked, serious trouble would be expected in the boilers, but, on the contrary, a recent inspection by a

Jan 1, 1908

Alfred C. Young† (communication to the Secretary): Before the appearance of Mr. Scott's paper in these Transactions we were not specially interested in the investigation which he has started; but at his request we have endeavored to collect from musty records and the recollection of our old friends a brief chronicle of the progress made by this house. As 3000 instruments were manufactured by us before any descriptive record was kept, and 2000 more before the record contained more than a statement whether the instrument was a transit or a level, and sometimes its size, we approach the task with timidity, trusting that the reader will bear the difficulties in mind, particularly as the writer's predecessors, from whom, no doubt, the information desired could have been obtained, have passed away. Instruments for surveying were manufactured by David Rittenhouse, of Philadelphia, as early as 1760; but it was not until late in the first quarter of this century that there was any American market for an instrument outside of the ordinary surveyor's compass. With the advent of canals and railroads, and the more extensive development of the Pennsylvania coalfields, arose a demand for surveying-instruments to meet problems in engineering beyond the limited field of the compass. On May 1, 1820, in which year the practical mining of anthracite coal in Pennsylvania began, William J. Young, who had served his apprenticeship with one Thomas Whitney,

Jan 1, 1901

By L. A. Roe, E. A. Elevatorski

Wollastonite, named after William H. Wollaston, an English chemist, is a calcium metasilicate, CaSiO3; CaO: 48.30%, SiO2: 51.70%. It has a short history as an industrial mineral. The earliest production of wollastonite is reported to be from a deposit near Code Siding, located north of Randsburg, CA. At this locality small tonnages of wollastonite were quarried during 1933-34 and 1938-41, and processed into mineral wool. This operation was largely experimental and virtually no United States production was again reported until the 1950s when a large deposit near Willsboro, NY, was developed by the Cabot Corp. A processing plant was placed onstream in 1953, with nearly continuous production to date. It is currently operated by NYCO, a division of Processed Minerals, Inc. Since 1958, wollastonite deposits in the Little and Big Maria Mountains of Riverside County, and in the Panamint Range of Inyo County, both in California, have operated intermittently for production of both ornamental and commercial wollastonite. During 1980, the United States was the major producing country, furnishing about 75% of the world's output. Current production comes from Finland, Mexico, India, and Kenya. Small amounts have been shipped intermittently from the USSR, New Zealand, Republic of the Sudan, Republic of South Africa, and Namibia (South-West Africa). The principal use of wollastonite is in the manufacture of plastics. Other uses are for paints, ceramics, adhesives, fluxes, glazes, thermal insulation board, and refractory products. Mineralogy Pure wollastonite, CaSiO3, has the composition of 48.3% CaO and 51.7% SiO2. However, it is seldom found in the pure state due to the ease with which it takes into solution the metasilicates of manganese, magnesium, iron, and strontium. Predominantly, wollastonite occurs as a contact metamorphic deposit forming between limestones and igneous rocks. Commonly associated minerals are garnet, diopside, epidote, calcite, and quartz. It has a specific gravity of 2.8 to 3.0, and hardness of 4.5 to 5 on Mohs' scale. When pure, it has a brilliant white color, but with impurities it may be grayish or brownish. Luster is vitreous to pearly. Melting point of wollastonite is about 1540ºC. Wollastonite occurs in coarse-bladed masses, rarely showing good crystal form. It is usually acicular or fibrous, even in the smallest of particles. The most unique property of crushed and ground wollastonite is its cleavage. Fragments of crushed wollastonite tend to be needle-shaped, imparting a high strength, and this property is the basis for many of its uses. The fiber lengths are commonly in the ratio of 7 or 8 to 1, length to diameter. The average diameter of wollastonite is 3.5 µm. Some crystals of wollastonite fluoresce under short-wave or longwave ultraviolet light, or both, with colors ranging from yellow-orange to pink-orange. Specimens may also show phosphorescence. The acicularity of wollastonite is a property of considerable importance to the marketplace. The plastics industry makes utilization of high aspect ratio grades of wollastonite (20:1) for reinforcing thermoplastics and thermoset polymer compounds. The naturally high pH of 9.9 (10% water slurry) is a prime property to the coatings industry. The coatings industry uses milled grades of wollastonite as a pH stabilizer in interior and exterior PVA and acrylic latex systems. Processed wollastonite can have a G.E. brightness of 90 to 93. Chemically, wollastonite is inert and this property makes it useful as a filler and reinforcing agent. There are two polymorphs of calcium silicates: wollastonite, a low temperature form, and pseudowollastonite, a high temperature

Jan 1, 1983

Analysis of Electrostatic Separation for Rutile Cleaning Duty Using a Plate Electrode Assisted High Tension Roll Separator A plate assisted electrostatic high tension roll separator has been used for the removal of impurity mineral grains from a rutile rich product stream. A laboratory study and a subsequent production study explored the effect of machine conditions with a view to the optimisation of the separation performance of the separator. The performance requirement was that the TiO2 grade in the non-conductor stream was to be less than ten per cent whilst at the same time the ZrO2 grade in the conductor stream had to be less than 0.5 per cent at mass recoveries of greater than 90 per cent to the conductor stream and less than 5 per cent to the non-conductor stream. Mineralogy data was utilized to determine the feasibility of achieving the production targets with the feed under study. Since the feed stream mineralogy was dominated by rutile, leucoxene and zircon, it was possible to use an approximation to the actual mineral assemblage as well as the raw X-ray fluorescence data to understand the separation duty of the Carrara machine. Since there were four conflicting criteria used for the performance requirement, an index was devised that incorporated all the requirements simultaneously. This new index was the sum of the squares of the difference between the achieved and desired values, weighted with respect to the variance of each variable. If the desired value for a particular criterion had been met its contribution to the sum was set to zero, no matter how well the criterion had been met. For the production machine the strict requirements were almost achieved. As expected, the achievement of the target performance was dependent of the feed conditions at the time of measurement. This paper reports the results of this study.

Sep 13, 2010

By B. K. Baird, P. C. Satchwell

The application of cutoffs during and after pit optimization is examined for a lower-grade multimetallic copper deposit. Pit optimization requires calculation of the net revenue associated with each mining block. The calculation incorporates parameters such as metal prices, grades and expected recoveries, mining and processing costs, smelting and refining charges, and penalty element and royalty charges. Sensitivity analysis during pit optimization reveals which parameters have significant effects on the total contained resource tonnage and total contained nondiscounted revenue in the optimized pit. The cumulative effects of changing several of the more-significant parameters are investigated The application of a copper cutoff grade to a block inside the optimized pit could result in the less-than-optimal extraction of the resource. A block with a copper grade below the applied cutoff could be economic due to the presence of other metals. Conversely, a higher-copper-grade block may be subeconomic. Also discussed are the merits of applying a copper-grade cutoff, an "equivalent-grade" cutoff and a dollar-per-ton cutoff to blocks inside the optimum nit.

Jan 1, 2002

By Norman O. Lotter, Simon Yu, Tony Deng, Antonio Di Feo

"Xstrata Nickel’s Raglan operation, northern Québec, achieved paymetal recovery gains in 2007 by switching the collector from potassium amyl xanthate to sodium isobutyl xanthate. To follow on from that position, Xstrata Process Support (XPS) and A. Di Feo of Raglan proposed that a mixed xanthate system be formulated and tested towards further performance gains. This work selected ethyl and isobutyl xanthates as the candidates. An optimized ratio of these was to be determined by a designed experiment. This suggestion was based on an abundance of published literature that reported mixed collector systems outperformed single ones. A partial factorial design was used to configure four test conditions and a mid-square for the flotation work. The testwork was conducted using High Confidence Flotation Testing. The raw data were analyzed and modelled by Design-Expert software. An optimum ratio of 1.6:1.0 by mass (1.32:1.0 in molar terms) of isobutyl:ethyl xanthate was determined. Without this modelling, the optimum ratio would have been missed. Results obtained with the new baseline flotation test using this optimized mixture showed a 3.3% Ni recovery gain in the bypass concentrate and more than 1% recovery gain for PGM over the single PIBX system. This system has been proposed for and accepted as a plant scale trial in the first half of 2010.INTRODUCTIONConcentrator OperationsMilling and flotation of sulphide ores ahead of smelting and refining is a common practice. This choice results in the larger and more variable paymetal loss in the production of saleable metal [Cramer, 2001]. For this reason, it is common to see an ongoing performance improvement programme at the operations level. When successfully performed, these e"

Jan 1, 2010

By Kal V. S. Sastry

Comminution is an important unit operation of mineral processing in terms of large tonnage of materials processed, huge energy consumption, and high capital and operating costs. Substantial research efforts have been directed towards the development of process-engineering tools including mathematical models, process scale-up procedures and computer simulation packages (Austin et al., 1984; Rajamani and Herbst, 1990; Kawatra, 1992). The simulation systems are found to provide significant cost savings by enabling efficient circuit design and development of control systems. Most of these simulators are built from scratch, do not make use of software modules from other sources and are designed with minimal usage of formal software methodologies.

Jan 1, 1995

By D. C. Hilty

C. E. SIMS*—This is a most interesting and important paper. It is important from two standpoints. First, it has as-spects of being highly accurate and therefore extremely useful to the operating man in showing how far he can go in oxidizing carbon from a steel bath while retaining chromium and the effect of temperature on this limit. Fig 5 is undoubtedly the highlight of the paper, and in checking it against available data, it seems capable of predicting actual results. The other important aspect is the apparently significant fact that reactions within a steel bath, such as between carbon and an oxide, are homogeneous reactions which do not require equilibrium with an external phase. In this case, it seems obvious that the reaction and the equilibrium established were between dissolved carbon (or carbide) and dissolved CrO. The classic reaction which requires equilibrium with solid Cr2O3, did not fit the data. It was recognition of this principle that made Fig 5 possible. G. R. FITTERER*—It might be in assuming the CrO is dissolved in the metal that you are actually approaching the correct factor for activity. If that is true and if the percentages that were used represent an equilibrium constant, this would mean, in effect, that the minimum temperature at which chromium would be reduced by an equivalent percentage of carbon would be about 2400°F from your equation. I believe that is in line with my experience particularly if you deal only with low percentages. J. CHIPMAN†—The author in discussing the equilibrium of the reaction offers two choices of explanation. One postulates an effect of chromium on the activity coefficient of carbon; it would require perhaps more data than are available to us at the present time to test this thoroughly. The other postulate which he offers is a reaction with CrO. This explanation is consistent with physical and chemical principles provided that a solid phase CrO is present, and that is essentially what he is postulating. If that oxide were present one would expect and, I think, almost require the kind of results that he obtained. The weakness of that postulate lies in the lack of confirmatory evidence regarding the presence of solid CrO as such. This should offer an interesting subject for further study. It seems a pity that the theoretical arguments revolving around CrO should have obscured for a moment the very real excellence of this paper. E. CARTER*—I think there is a problem that presents itself in practical application where the metal temperature is from 3200 to 3300 and the temperature desired in pouring is considerably less. B. M. LARSEN†—I get the impression from some of the work that was done earlier that there is probably a localized zone of high temperature at the slag metal interface which effects the removal of the carbon. Without that I wonder if the effect is possible to have a localized superheat and an equilibrium there favorable to low carbon content and

Jan 1, 1950

By Martin Knights, Geoff Featherstone, John Flanagan, David Lawrence

The proposed paper will address specific transport, engineering, environmental and community related issues concerning the current construction and future operation of Europe’s biggest urban road tunnel project—the US$500m Dublin Port Tunnel. Situated in Ireland’s capital, the three mile long, 40 ft diameter twin tunnel project encounters a range of ground conditions using TBM, Shield, Cut & Cover with diaphragm walling and major slope stabilisation and Multi-jacked pipe techniques. Where possible units of measurement are given in feet and inches.

Jan 1, 2003

By Jasper L. Stuckey

PYROPHYLLITE, first identified as soapstone,1 later as agalmatolite,2 and finally as pyrophyllite,3 has been known to occur in North Carolina for more than 130 years and has been produced intermittently in commercial amounts for the past 100 years. Pyrophyllite mining, however, has become a major industry in North Carolina only during the past 25 years. North Carolina and California are the chief producing states. Current annual production averages 125,000 tons, of which slightly more than 90 pct comes from North Carolina. Distribution and Geologic Setting: All known pyrophyllite deposits in North Carolina are associated with rocks of the Carolina Slate Belt,4 which is composed of a vast series of metamorphosed volcanic and sedimentary materials, occurring as two zones extending in a northeast-southwest direction across the state. The larger of these zones, lying in the central Piedmont region, varies from 8 to 50 miles wide. The smaller zone lies along the eastern edge of the Piedmont region and is partly covered by coastal plain sediments.

Jan 1, 1958

By G. A. Brown

"Mining executives are becoming increasingly involved with decisions of the ""What would happen if ... "" variety. Potential changes in government policy, such as tax incentives, E.G.M.A. allowances, etc. affect the economic future of present and proposed mining ventures.This paper will discuss various measures of effectiveness normally used in assessing this future, such as discounted cash flow, etc., and will describe means of introducing uncertainty into the computations. As the recognition of risk and attitudes toward accepting it are very important in the life of a mine executive, there will be a brief discussion of utility theory and its application to risk analysis.Risk models are usually of a size to warrant the use of an electronic computer. Therefore, to demonstrate the simple interaction necessary between a financial analyst and such a model, data will be read into a remote computer from a time-sharing terminal in the meeting room. It will be shown that changes may be rapidly made and alternative policies investigated ""on line"" to a computer."

Jan 1, 1970

By Robert E. Mclvor

Classification system efficiency (CSE) is a simple metric that can be used to measure and increase ball milling circuit efficiency. It is defined as the percentage of the ball mill energy being used to grind target (oversize) particles. This paper describes CSE analysis conducted for a variety of operations with related improvements in circuit efficiency ranging from 3 to 30 percent. The achievable CSE for any given ball milling circuit is described, providing the means to determine the extent to which every plant can benefit from increasing grinding circuit CSE.

By Michael Godard, Peter Cleyle

"Suncor Energy’s Project Millennium increased oilsands production capacity by an additional 95,000 barrels per day to its present level of 225,000 barrels per day. This massive venture included an expanded Mine, new Extraction and Upgrading facilities, as well as, steam and utilities infrastructuresIn the Primary Extraction process, removal of the bitumen from the oil sand begins with slurry preparation and is followed by primary , secondary and tertiary separation processes. The final cleaning step of the bitumen froth is the Secondary Extraction process, that removes residual water, mineral and solids to produce a clean diluted bitumen suitable for Upgrader feedstock.This paper will review the flowsheet of the Millennium Primary Extraction facility, from its recent commissioning through the ramp up to design production rates. In addition, new technologies in the Primary Extraction flowsheet will be reviewed.INTRODUCTIONAs conventional supplies of oil and gas are depleted in Canada, the Athabasca oil sands industry of Alberta becomes an increasingly important source of energy. Today, high quality crude from Alberta’s oil sands accounts for roughly 30% of Canada’s daily petroleum production. According to government projections, over the next 7 years, oil sands production is expected to more then double, and by 2010 more than half of Canada’s crude oil is expected to come from the oil sands.Oil sands deposits consist of a layer of sand saturated with bitumen covered by a muskeg overburden and underlain by silt and clay. The oil sand is mined where the overburden is economical to remove, typically less than thirty meters thick. The Athabasca oil sand deposits around Fort McMurrray is ideal for mining. Bitumen can be described as a diverse collection of hydrocarbons, organosulfur, and nitrogen compounds."

Jan 1, 2004

By Christa Quiroz

"La energía liberada al detonar los explosivos genera diversos efectos como fragmentación, fracturación y deformación del material dentro del cual el explosivo es detonado. Sin embargo, existen otros efectos secundarios: proyecciones de roca, formación de nubes de polvo, ondas aéreas, ruido y formación de vibraciones sísmicas. En ese sentido, el presente trabajo describe tres métodos utilizados en minería superficial para monitorear vibraciones causadas por voladura, con el fin de establecer cuidados y controles según el tipo de suelo. El primero refiere al monitoreo de vibraciones, el cual es una técnica que permite evaluar el rendimiento general del diseño de la voladura. El segundo refiere la técnica “CrossHole” donde se realiza una buena evaluación del daño al macizo rocoso y el tercero implica el “Criterio de Daño” como una función del PPVmáx. "

Oct 21, 2015

Under the joint auspices of the Illuminating Engineering Society and the University of Pennsylvania there will be given about 20 lectures covering the general principles of illumination and the aspects of lighting practice. They will be held at the University of Pennsylvania in Philadelphia, from Sept. 21 to 28, 1916, inclusive. The subject of illumination of mines will be included in this series, which will be delivered by men selected on account of their qualifications to deal authoritatively with the several phases of the subject. In connection with the lectures there will be an exhibition of the latest developments in illuminating appliances, including lamps, accessories, photometers, together with novel applications of light. There will also be an inspection tour which will include visits to manufacturing establishments, laboratories, lighting companies and notable lighting installations. For further particulars apply to the Illuminating Engineering Society, 29 West 39th Street, New York City.

Jan 6, 1916

By R. Bruce Ferguson

"The Kettle River Operation of Echo Bay Minerals Company is located about thirty kilometers north of the town of Republic in northeastern Washington State. In tum, Republic is about a hundred and seventy kilometers north and a little west of the city of Spokane, Washington. It is also about fifty kilometers south of the town of Grand Forks, BC, Canada. At this time it is the only gold mining and milling operation in the State.Tailings are stored in a double lined, zero discharge facility. It became evident in mid 1996 that the rate of free water accumulation in the tailings pond was going to result in the level in the pond reaching its permitted freeboard elevation long before the solids plus pore water capacity was reached.We then embarked on a mission to manage tailings pond water on several fronts: reduce fresh water usage in the process, divert spring seeps and surface runoff and install a system to enhance evaporation.IntroductionThe Republic area is an historic gold mining district. Hecla operated its Republic unit from 1892 until closure in 1994. The Kettle River Operation processing plant is located in the San Poi! river valley at an elevation of just under a thousand meters. The facility consists of a ninety thousand ton ore storage pad as the mines are remote and truck haulage is subject to interruption due to weather and road restrictions, jaw and cone crushing with screening, rod and ball milling to an eighty percent passing size of seventy five microns. This is followed by preaeration with high purity oxygen supplied by a vacuum pressure swing adsorption plant plus lead nitrate addition to achieve passivation of the sulfide mineralization such as chalcopyrite, pyrite and pyrrhotite. Conventional cyanide leaching and carbon in pulp adsorption completes the loop. Tailings are treated with air/S02 to achieve cyanide destruction. Plant capacity is 1,815 tons per day. Our license requires that there be no detectable free cyanide in the tailings pond water and a maximum of forty parts per million weak acid dissociable cyanide. The operation started in 1989 with production from the Overlook Mine located about five kilometers further up the same valley at an elevation of twelve hundred meters, hence the location of the mill. Current mine production comes from Lamefoot in the Curlew Lake valley, about ten kilometers distant, and K2 in the Kettle River valley about fifty kilometers away. Both are at an elevation of about 800 meters. Lamefoot produces 1,360 tons per day and K2, 455. Both are underground operations."

Jan 1, 1998

By Robert E. Haun

Retech's Plasma Arc Centrifugal Treatment (PACT) system is a thermal technology that uses heat generated by a plasma torch to treat hazardous waste containing metals and/or organics. Metal bearing solids and soil are melted by the process, and organic contaminants are thermally destroyed. The molten material forms a hard, glass-like leach resistant mass after cooling in a mold. This paper discusses plasma processing in general and presents some results of treating mineral processing wastes using the plasma arc centrifugal treatment process.

Jan 1, 1995

By A. J. Fenn

Long experience with underground mining inspired the unusual idea of using an underground crusher-conveyor system as a substitute for surface haulage at the Cananea open-pit copper mine in Sonora, Mexico. Now implemented and working well, the system has born out the expectations of its originator, Cia. Minera de Cananea S.A. de C.V., that it would effect substantial cuts in the high cost of haulage. The Cananea deposit is a large, low-grade orebody above the mined-out Colorada pipe which was once one of the largest high-grade underground deposits in the district. Present facilities at the pit consist of: (1) A large open-pit mine capable of moving 80,000 tons of material per day with a shovel-truck, underground crusher and belt conveyor haulage system. (2) A 25,000-tpd concentrator equipped for four stages of crushing, rod mill-ball mill grinding with cyclone classification, and flotation in conventional machines. (3) A dump leaching process producing 1 million lb of copper per month in a tin-can scrap precipitation plant. (4) A two-reverberatory, six-converter smelter which can make 140 tons of blister copper per day. (5) A well-integrated contingent of supporting departments running the gauntlet from housing to power generation.

Jan 3, 1969