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By Jack Haptonstall

INTRODUCTION The mines of western central Mexico historically contributed a profusion of gold and silver for the treasury of Spain and later provided sources for financing the Mexican War for Independence and the Mexican Revolution. The western coastal and barranca (cliff) tribes were hunters and extremely hostile, and the Spaniards were not able to penetrate many of the rich districts of their rugged homeland until the mid-1700's. This was more than 200 years after Cortez began the Inquisition by defeating the Aztecs and their allies in a decisive battle in the great city of Tenochtitlan (present day Mexico City). The Spaniards had a voracious appetite for silver and gold, and it was inevitable that they would finally subdue the natives and commence mining activities. Described in this paper are some of the precious metal mining activities in the southern half of the State of Sinaloa and the western half of the State of Durango (Figure l), and specifically those mining activities in the area controlled by the company with which the author was associated for 14 years, Minas de San Luis, S. A. de C. V., the parent company of which is now Industrias Luis Min, S. A. GENERAL DESCRIPTION Geography, Logistics and Climate The most spectacular of the physiographic provinces, the western Sierra Madre Occidental is the cliff or "barranca" province, the

Jan 1, 1983

By R. R. Odle

A laboratory and pilot-scale investigation of direct smelting of copper concentrates was conducted to determine the effect of concentrate analysis and the degree of roasting on the yield and quality of copper produced in a subsequent smelting step. A stoichiometric :mOdel of direct smelting is presented which predicts the? quantity of copper; slag, and white metal' prOduced'and the distribution of copper in these phases as a function? of the concentrate '(calcine) analysis.

Jan 1, 1983

By P. C. Schutte, N. B. Strydom, A. J. Kielblock

Three groups of unacclimatized men were subjected to five-day climatic-room procedures at wet-bulb temperatures of 29,30, and 31 C respectively. The findings indicated that individuals reach a satisfactory level of heat acclimatization for work in environmental temperature conforming to those at which they were acclimatized. It is, therefore, superfluous to acclimatize men at wet-bulb temperatures that exceed those at which they are destined to work. These methods of acclimatization can be linked advantageously to heat-tolerance testing at mines with suitable underground temperatures.

Jan 1, 1983

By Bryson D. Trexler

Slope stability in open pit mines is governed by rock structure, rock quality, ground water conditions, blasting, pit geometry and excavation method. Of these factors, the control of ground water pressures often represents the primary tool to improve slope stability. Production equipment has recently been used to stabilize two slide areas by dewatering using blasthole drills for vertical holes and secondary drills for horizontal holes. This paper describes both of these dewatering programs and contrasts an earlier slope stabilization program that employed a subcontracted horizontal drill.

Jan 1, 1983

By Levent Ozdemir, Robert J. Evans, Russell J. Miller, William Sharp

This paper describes the specifications and capabilities of a 6 ft (1.83 m) diameter laboratory rotary cutting machine which was designed and fabricated under a Bureau of Mines (USBM) contract awarded to the Colorado School of Mines (CSM). The machine will be used for carrying out research and development programs aimed toward improving the design and operation of mechanical tunnel, raise and shaft boring equipment.

Jan 1, 1983

Past issues of Minerals and Materials have discussed such aspects of the economy as consumption and investment expenditures, interest rates, productivity, and international trade barriers and their effect on the minerals industry here and abroad. In this issue, we will (l) look at recent indications of a possible economic recovery, (2) present 1983 expectations reflecting the results of industry surveys conducted by the U.S. Department of Commerce (DOC), and (3) briefly discuss the contribution of the U.S. mining industry to total gross national product (GNP). THE RECOVERY Throughout most of 1982, DOC's Composite Index of Leading Indicators provided evidence of impending improvement in the economy. The index increased moderately during eight of the months in 1982 and then jumped an estimated 3.6 percent in January 1983 (table 1). While the leading indicators continued to predict improvement, the general economy, as measured by the Index of Industrial Production, continued its slide through November 1982 (table 2). Finally total industrial production increased in December 1982 and continued on an upward path in January and February, as predicted by the leading indicators.

Jan 1, 1983

By David E. Thompson, Andrew F. McKown, Herbert H. Einstein, Amr S. Azzouz

INTRODUCTION Design of supports for underground chambers in rock has undergone considerable development. This becomes evident when comparing support dimensions of subway station caverns built in the U.S. over the past fifteen years. The Porter Square Station cavern, which is a part of the Massachusetts Bay Transportation Authority (MBTA) Red Line extension, is the latest in this series. It is approximately 168 m (550 ft) long, 21 m (70 ft) wide, and 14 m (45 ft) high, and has a permanent support of light steel ribs imbedded in a 0.4 m nominal (15 in) shotcrete lining. An extensive construction control instrumentation program made it possible to evaluate the performance of the cavern and its support. This evaluation, which is presented in this paper, was the objective of a research project sponsored by the Urban Mass Transportation Administration (UMTA) and jointly conducted by Haley and Aldrich, and MIT. The actually used design procedure was compared with other approaches, notably procedures based on Finite Element analyses and empirical rock mass classification methods. Support dimensions predicted with all these approaches were compared to the actual support and its performance.

Jan 1, 1983

By Meherwan C. Irani

The Bureau of Mines is developing a new technological approach to handling the problems of fires in abandoned coal mines and waste banks. This new technology involves the accelerated combustion of "waste" coals in place (i.e., in situ) under controlled exhaust ventilation conditions, which allows for total management of the combustion products; including utilization of the heat produced" This new concept could significantly lower the costs of reducing the environmental and public safety hazards associated with waste coal fires, and could lead to the conversion of a coal waste to a coal resource. The controlled burnout technology has progressed from the laboratory stage to a full-scale field evaluation stage at the site of an abandoned-coal-mine fire. This first report describes the site selection, evaluation, and preparation, and the design and construction of the full-scale controlled burnout installation. Subsequent reports will deal with the results of the operational field trial.

Jan 1, 1983

By G. E. Agar, J. J. Barrett

"Traditionally, batch bench-scale flotation tests have been used for evaluating flotation reagents by comparing the results of tests done with various additions of the reagent in question. Usually, comparisons are made of the concentrate grade and recovery or some figure of merit involving an empirical combination of both. In some cases, statistical methods have been used to make the comparison and even to identify optimal combinations of reagents.None of the preceding technology utilizes the fact that flotation separations can be described by relatively simple kinetic equations that will serve not only to quantitatively describe the influence of a reagent, but will also aid in designing an optimal separation procedure. Examples of the use of a first-order rate equation for evaluating the impact of a reagent addition and for optimizing the reagent addition are given.IntroductionThe classical method of evaluating flotation reagents is to conduct batch bench-scale tests while varying one factor at a time. Some of the shortcomings of this technique have been pointed out and statistical design and evaluation of experiments has been advocated. Although the statistical approach is superior to the one-at-a-time method, it still is dependent on the results of a batch test conducted for a specific duration.That flotation is primarily a rate process than can be described by a first-order rate equation has been recognized for a long time, but the application of this knowledge to the evaluation of reagents has received little attention. In this work, it is demonstrated how the parameters of the first-order rate equation can be utilized to evaluate the influence of reagents on flotation."

Jan 1, 1983

By T. W. Smelser

This Bureau of Mines report presents a review of underground testing, test results, and design guidelines of steel-fiber-reinforced concrete (SFC) mine support (cribbing) developed at the Spokane Research Center. The objective of the work was to verify, in field applications, the performance, economics, and acceptance by the mining industry of the SFC supports and establish design guidelines for their use underground. Results indicate superior performance, favorable economics, and enthusiastic acceptance by the mining industry.

Jan 1, 1983

By Donald D. Carr, Lawrence F. Rooney

Perhaps no other mineral commodity in this volume has as many uses as limestone and dolomite. These carbonate rocks are the basic building blocks of the construction industry, the material from which aggregate, cement, lime, and building stone are made. Carbonate rocks, and their derived products, are used as fluxes, glass raw material, refractories, fillers, abrasives, soil conditioners, ingredients in a host of chemical processes, and much more. Although the use of limestone and dolomite goes back before recorded history, new uses and products are continually being found. Carbonate rocks form about 15% of the earth's sedimentary crust and are widely available for exploitation. Found extensively on all continents, they are quarried and mined from formations that range in age from Precambrian to Recent. Reserves of carbonate rock are large and will last indefinitely, although high-purity deposits may be absent or have limited availability in certain areas. Limestone and dolomite are so useful and so abundant that in 1981 about 644 million tons were produced in the United States. In fact, about 75% of all stone quarried or mined in the United States was carbonate rock. Sand and gravel was the only mineral commodity produced in greater quantity. In this chapter we have sought to provide the general reader an overview of carbonate rocks, their composition, distribution, production, and uses, with emphasis on developments since 1960. In doing so we borrowed extensively from our report on the applied geology of limestone and dolomite (Rooney and Carr, 1971). The literature on the limestone and dolomite resources of the United States and Canada is so vast and diverse that one can easily become mired down in print. We tried to list those references that are easily accessible and that provide the economic geologist with a starting point for more intensive study. The table listing selected references on limestone and dolomite resources in Canada and the United States reflects our attempt to be selective rather than exhaustive and to direct the reader to the best sources of detailed information. Geology Mineralogy The principal carbonate rocks used by industry are limestone and dolomite. Limestones are sedimentary rocks composed mostly of the mineral calcite (CaCO3) and dolomites are sedimentary rocks composed mostly of the mineral dolomite (CaCO3 • MgCO3). Aragonite (CaCO3), which has the same chemical composition as calcite but a different crystal structure, is economically important only in modern deposits, such as oyster shells and oolites. Aragonite is metastable and alters to calcite in time. Some other carbonate minerals, notably siderite (FeCO3), ankerite (Ca2MgFe (CO3)4), and magnesite (MgCO3), are commonly found associated with limestones and dolomites but generally in minor amounts. Because of their similar physical properties, the carbonate minerals are not easily distinguished one from the other. Specific gravity,

Jan 1, 1983

By W. V. Bluck

Higher coal quality is being recognized in potentially lowering the cost of power as measured at the bus bar. Assessment of potential coal supplies for most any given power plant is now going beyond buying at the lowest delivered fuel cost and is now taking into consideration other factors such as handling, storage, pulverization cost, boiler fouling, post combustion cleanup, and waste disposal costs. New measurements of quality are being considered now by those producing and those consuming the fuel by assessing numerous variables in the total fuel cycle to achieve the lowest possible power costs.

Jan 1, 1983

By L. P. Kleinmann

To control the formation of acid drainage at its source, the Bureau of Mines has investigated the role of iron-oxidizing bacteria in the oxidation of pyrite. In laboratory tests, it was determined that Thio-bacillus ferrooxidans could be controlled in coal refuse using anionic surfactants, with an associated decrease in acid production of about 75 pet. Based on these results, large-scale tests were conducted at an 8-acre active coal refuse area in northern West Virginia and an 11-acre inactive refuse pile in southern West Virginia. Acid production was decreased 60 to 95 pet for 4 to 5 months after application of 55 gal/ acre of 30-pct sodium lauryl sulfate solution. To date, effluent surfactant concentrations have been extremely low. Either a hydroseeder or a road-watering truck can be used to apply the surfactant. Since the surfactant solution must reach the pyritic material to be effective, sites that have been reclaimed are generally not amenable to these procedures. A simple laboratory test is described that provides an estimate of adsorption potential; this can be used to calculate a safe application rate.

Jan 1, 1983

By Wallace W. Roepke

The Bureau of Mines tested new designs of drag bit cutters with sintered diamond inserts instead of standard tungsten carbide tips. The bits were tested for orthogonal cutting forces, primary dust generation, and incendivity, with a standard plumb-bob type conical cutter (600 included tip angle) as the reference. Preliminary wear and impact-failure testing were also done. The results were mixed. Two new designs had forces similar to those of the reference bit, but one new design had about twice the normal force. This same design had almost twice the specific energy during shallow cutting but generated an equal or slightly lower amount of primary dust than did the reference bit. Incendivity was eliminated for two radial designs. One conical design had ignition only after more than 15 impacts, but the other conical design was incendive. Impact failure occurred, but not so quickly as anticipated. Over 7,500 impacts on a sandstone face, with a total cutting distance of more than 1,981.2 m, only scuffed the leading edge of the sintered diamond cutting face but put hairline cracks in the substrate mounting pad. Additional design and testing are needed to develop an optimum cutter, but prospects look good for this material.

Jan 1, 1983

By David J. McDougall

"IntroductionThe production of pig iron, wrought iron bars and castings in Quebec during the 18th and 19th centuries has been so closely identified by historians with the Forges du St. Maurice on the St. Maurice River a few miles north of Trois Rivières (Three Rivers), that one is sometimes left with the impression that it was the only iron works that ever operated in the province. There were however, about twelve others, one of which was so completely re-built that it should probably be considered as a separate entity. All but two were constructed after the midpoint of the 1800s, coinciding with the growing Canadian demand for ""charcoal pig"" for railway car wheels and castings for industry, and about half of them were technically, if not economically, successful. The misconception about the Forges du St. Maurice may have come about either because of its long history of somewhat less than continuous production over a century and a half, or a tendency of Quebec historians to concentrate on events in the French-Canadian rather than the English-Canadian milieu, but whatever the reason, the other Quebec iron work s have been generally ignored. All but one of the Quebec blast furnaces could be described as ""preindustrial"" with capacities ranging between three and ten tons per day, the exception being the Radnor furnace built in 1892 with a maximum production of about 35 tons per day and an alleged capacity of 50 tons per day.Until a railway network was completed in the 1880s, the location of all the Quebec iron works except the Grantham Iron works was dictated by close proximity to adequate ore reserves because horse transport was of little use beyond a ten-mile radius. The other essentials of forest resources (mainly soft woods) for charcoal, limestone for flux and water power, were generally available except within a few miles on either side of the St. Lawrence river. Among the dozen iron works established in Quebec between 1732 and 1880, seven used bog iron ore in charcoal-fired furnaces."

Jan 1, 1983

By D. F. VanDine, H. George

"The possibility of spoil pile failure at the Kara Kara bauxite strip mine, Guyana, South America, is of major concern to the mine operators. The current mining technique requires the continuous operation of an 11 ms bucket capacity walking dragline on top of 18 metres of freshly spoiled uncompacted overburden material consisting of varying mixtures of kaolinitic clay and quartzitic sand. A field biased geotechnical study of undisturbed overburden and corresponding spoiled material has identified site-specific, non-linear correlations between vane shear strength, standard penetration resistance and spoil pile composition. Readily available geological exploration borehole logs has enabled a composite clay isopach map of the entire mining property to be drawn and critical areas to be zoned according to expected slope stability. Stability has been assessed using simple hand calculation techniques. Use of the resulting stability map provides the mine operators with a means of forecasting the need for appropriate preventative measures at varying stages of mine development, throughout the life of the mine.A similar investigation procedure could be employed at many presently operating and future strip mines.IntroductionThe Kara Kara bauxite stripe mine is located at Linden within the bauxite belt of Guyana in South America. The mining property covers a total area of 88 hectares of flat to gently sloping ground of which some forty per cent is being actively mined or being preparatorily stripped of overburden, prior to eventual mining (George and Gordon, 1979). The regional climate is tropic and humid. Temperatures vary from 16°C to 38°C and yearly rainfall averages 2600 mm, with at least 55 per cent of this precipitation occurring during the 'wet season' months of May to July and December to January."

Jan 1, 1983

By D. S. Nilsson

Small-scale mines are today expected to provide much of the increased production of metals and coal this county demands. But in fact the category of larger mines tends to grow in number and size faster than the category of smaller mines. Larger mines show the highest productivity, the lowest injury frequency, and the lowest costs. Lower cutoff grades can be wed in larger mines. The paper describes how the production level affects the choice between different types of loading, haulage, and hoisting equipment; how the increased production level in a mine results in lower production costs per ton; and how this affects the profitability of mining deposits with various ore grades. The future trend is expected to favor larger and larger operations.

Jan 1, 1983

By Richard B. Jacob

The High Gradient Magnetic Separator (HGMS), also known as the High Gradient Magnetic Filter (HGMF), is an effective device utilized in magnetic separation. This method of separation is gaining popularity in the separation of sub-micron material containing feebly magnetics. The most common use of this type of separator is in the removal of iron stained particles to improve the brightness of kaolin clay. Potential areas for use of this magnet include: (1) desulfurization of coal (2) the clean-up of mill effluent (3) removal of fine particulate matter from municipal and industrial waste (4) desulfurization of oil

Jan 1, 1983

By K. O. Bennington

Cancrinite is one eonstituentof "red muds," a high-volume waste product of alumina production by the Bayer process. The Bureau of Mines determined the thermochemical properties of cancrinite as part of a program to provide such data for minerals of industrial importance. Cancrinite [Na7.68(A16Si6024)(N03)1.68 (H2O)4.1] was synthesized by reacting aluminum silicate gel with a solution of NaOH and NaN03, and the composition was determined by chemical analysis, differential scanning calorimetry, and thermogravimetric analysis. The heat of solution was determined by hydrofluoric acid solution calorimetry. The standard enthalpy of formation at 298.15 K, ?Hf°298, is ?Hf°298 = -3,487.97 ±2.6 kcal/mol, and the standard enthalpy of formation from the oxides and NaN03, ?H°298, is ?H°298 = -215.20 ±l.8 kcal/mol.

Jan 1, 1983

By James T. Finley

Profit, product quality, speed of operations, reliability, operator confidence, safety and environmental improvements have all been enhanced as a result of the recently completed maintenance, renovation and construction program at Crown Central Petroleum Corporation?s (Crown?s) coke calcining unit at its Pasadena, Texas refinery. (Figure 1) BACKGROUND The calcining unit was built in 1969 - 1970 and has been operated continuously. Approximately 400 to 500 TPD of high quality metallurgical grade coke is manufactured, stored, and shipped to consumers. About 1/2 of the feed stock to the calciner is manufactured in Crown's coking unit and the remainder is received, via barges, from various sources. The green coke is off loaded from the barges with a conventional grab crane that discharges into a small travelling hopper over a conveyor belt that feeds a radial stacker, which forms a stockpile on the ground. The green coke, from the coking unit at the refinery, is moved to the calcining unit with front end loaders. Reclaiming from the stockpiles is also done with front end loaders. The coke is primarily handled by covered conveyor belts. The finished product is stored in steel silos and can be shipped via railroad cars, but the majority of it is shipped out in ocean going bulk carriers. Maintenance work in the calcining unit is performed by Crown's refinery maintenance department on an as needed, on call basis.

Jan 1, 1983