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By L. R. Chirinos

The Tintaya mine of BHP Copper, located in Southern Peru, includes a copper oxide deposit hosted in a mineralized skarn zone. The ore contains large amounts of clays and high acid consuming species resulting in low heap leaching performance. A treatment scheme was proposed that included a wet screening separation. The coarse fraction would be treated by heap and the fines by agitation leaching. The dissolved copper would then be recovered through solvent extraction and electrowinning (SXEW). Testwork determined the optimum heap leaching conditions to treat the oxide in on/off pads of 3 meter height with an initial acid cure followed by variable acid strength during irrigation. The method resulted in a reduced acid consumption and good copper recoveries.

Jan 1, 1997

By G. C. Knutsen

The Post deposit is located in Eureka County, Nevada, about 37 km (23 miles) northwest of the town of Carlin. Post occurs on the Carlin Trend, a northwest alignment of 14 major gold deposits, each containing more than three tonnes (t) (100 000 ounces) of gold. Deposits of the Carlin Trend are epithermal, sediment-hosted, disseminated gold occurrences, collectively containing more than 622 t (20 million ounces) of gold. Three major gold producers active on the Carlin Trend are Newmont Gold Company (NGC) (12.4 t/400 000 ounces of gold per year), Western States Minerals Corporation (WSMC) and Pancana Minerals joint venture (1.56 t/50 000 ounces of gold per year), and Dee Gold Mining Company (1.4 t/45 000 ounces of gold per year). The Carlin Trend has also been referred to as the Lynn-Railroad Mineral Belt. This district is characterized by open-pit mineable, micron-sized gold, hosted in Paleozoic sedimentary rocks. Six geological subdistricts comprise the Carlin Trend, each characterized by differences in host lithology, structural controls, alteration assemblage, or style of mineralization. The six geologic subdistricts include, from south to north, Bullion (Railroad), Rain, Maggie Creek, Lynn, Bluestar-Goldstrike, and Bootstrap. With the exception of the Bullion subdistrict, which was primarily a producer of base metals, each sub-district contained mineable reserves in excess of 31 t (one million ounces) of gold.

Jan 1, 1987

By William W. Shriver

When the Henderson Project is completed in 1975, it will become one of the Free World's largest primary molybdenum producers. The Henderson Mine will be located approximately 50 miles west of Denver, Colorado, on the eastern slope of the Continental Divide. Ore reserves are currently estimated to be 303,000,000 tons with a grade of 0.49% MoS2. The mill and tailing area will be located approximately 14.5 miles from the mine in the Williams Fork Valley, which is on the western slope of the Continental Divide. Ore haulage from the mine to the mill will be by ten miles of underground railroad and 4.5 miles of surface railroad. The concentrator has been designed to mill 30,000 tons per day and will yield approximately 50,000,000 pounds of contained molybdenum per year. This paper is concerned with the tailing and water supply system for the Henderson Project and in particular the environmental considerations affecting their design.

Jan 1, 1970

By Harold D. Palmer

The marine geologist and coastal engineer have at their disposal a wide variety of geophysical tools with which to investi¬gate sea floor topography and structure. Such devices include towed magnetometers, shipboard gravimeters and a variety of acoustical systems for recording the relief of the sea floor and buried structural features. The versatility of this latter group of systems lends itself to a variety of applications essential to those projects where excava¬tion of the sea floor is required. This paper describes the use of several acoustic devices and their Limitations and presents a case history in which a rapid survey from a small vessel provided detailed information critical to the planning stage of a specific coastal project. In this discussion, shallow water is defined as depths less than 150 feet. At present, this limit includes the maximum depth of economic dredging and most other offshore activities. To be sure, the maximum depth at which routine useful work can be accomplished is rapidly increasing, but the majority of current marine activities are located in water depths here defined as shallow.

Jan 1, 1968

By Stanley C. Suboleski

The increase in productivity which has been achieved in mining during the past two decades has been attained largely through the replacement of manpower with electrical power. Power demands should continue to increase, requiring electrical distribution systems to be well planned to avoid inadequate voltage levels caused by underdesign and excessive costs resulting from overdesign. To aid the mining electrical engineer in designing proposed power systems or analyzing changes to existing systems, a digital computer program has been developed. This program will analyze alternating or direct-current networks with up to 10 voltage sources, 75 loads and 300 total segments. A maximum of nine levels of voltage is permitted in the system. This project was part of a package of programs developed at Virginia Polytechnic Institute (WI) for the mining industry under sponsorship of the Office of Coal Research. Included in this package are also programs to: 1. Schedule mine production and predict cost of mining 2. Simulate rail haulage systems 3. Simulate belt haulage systems 4. Analyze ventilation networks 5. Analyze pumping networks These programs are available from the Department of Mining Engineering, VPI, Blacksburg, Virginia 24061 for a nominal processing cost.

Jan 1, 1970

By E. M. Haynsworth

The disposal of phosphatic clays has presented a problem to the phosphate industry since the mining of phosphate rock first began. As the flotation process was introduced in the late 1920's, the problem of clay disposal was increased significantly since clay is present in proportionally greater quantities in reserves yielding flotation concentrates. Because of their physical character and the tremendous surface area per unit volume, these clays have the characteristic of retaining large volumes of water as they are slurried during processing. The phosphatic clays with which we are dealing consist primarily of apatite, wavellite and montmorillonite. In the beneficiation process, we remove the -150 mesh material as waste. However, the particles are essentially smaller than -325 mesh, and more than 70% are smaller than three microns. The disposal of clay and the recovery of a portion of the water require settling areas with a capacity ranging up to 2 cubic feet for each cubic foot of phosphate matrix mined. According to a recent study by the Bureau of Mines, the average cost for disposal of these wastes is 24.5 cents per ton of, product (U. S. Bureau of Mines Circular 8404). This is a major cost of phosphate rock production.

Jan 1, 1970

By Fred H. Lightner

The feasibility evaluation of the Borealis project of Houston International Minerals Corporation (HIMCO) was initiated in October of 1980. The operation of the Borealis Mine and heap leaching plant began in late 1981. In order to achieve the rapid development schedule several items were necessary: 1) Pre-planning of environmental requirements and early study of key issues. 2) Adoption of conservative design criteria. 3) Coordination and cooperation between HIMCO and regulatory agencies. 4) Adoption of specialized engineering and construction procedures. 5) Careful evaluation of owner project management philosophy.

Jan 1, 1982

By L. U. Spellman

Atlantic Cement Company's new multimillion dollar, 10,000,000 barrel per year cement plant went into full operation in February, 1962, bringing into reality a new concept in the distribution of Portland cement. The Cerro and Newmont Mining Corporations, well established in the mineral extraction and dressing industry, backed the venture. To take advantage of the, economics inherent in single production units of large capacity, it was necessary to first find a market' capable of absorbing such large quantities. Cement can be economically shipped by rail and truck about 200 miles. Beyond' that radius from the producing facility the freight costs become prohibitive. No single marker area within that radius exists which could absorb such a large volume of cement. However, water transportation provides a relatively inexpensive method of transporting bulk products many times over such a distance. Thus, it was decided to locate the producing facility near a deep water port which had ready access both to the Atlantic Ocean and, just as important, a good source of raw material. An extensive feasibility study was made and the site at Ravena, New York on the Hudson River near Albany was chosen. Here, vast quantities of limestone in the foothills of the Catskill Mountains are found within a short distance of-the deep-water Hudson River.

Jan 1, 1964

By Warren W. Frech

11.1-FRAGMENTATION PRINCIPLES WARREN W. KRECH Energy must be supplied to rock by direct or indirect means to fragment that rock. The amount is dependent upon the properties of the rock and the type of loading system. Fragmentation energy is consumed by three main mechanisms: (1) creation of new surface area (fracture energy), (2) friction (plasticity) and (3) elastic wave energy dispersion. The loading method determines the relative proportions and the amount of energy consumed in fragmenting a given rock type. Unconfined tensile failure consumes the least energy, with an increasing amount of energy required as the rock is more highly confined within a compressive stress field during fragmentation. The way energy is applied by tools to cause rock or mineral fragmentation is important in determining fragmentation efficiency. Rock-tool interaction should always be controlled to the fullest extent possible to optimize the combination of rate of energy input and fragmentation energy requirements. While the direct cost of energy, (dollars per horsepower-hour) may at first glance appear low relative to other hourly costs, there is a tie between power consumption and other cost factors, such as maintenance and wear. A high rate of energy application utilizing a rock-tool interaction producing only unconfined tensile failure would provide the most efficient fragmentation. No tool that produces a combination of high energy input rate and a loading system that produces failure under only conditions of unconfined tensile load now exists. Present mining methods and tools produce failure under conditions of high compressive confinement, high dispersive energy loss and high frictional energy requirements. Thus, while generally applying energy at high rates, they are highly inefficient with respect to energy consumed in fragmenting rock. To best design fragmentation tools and optimize fragmentation systems it would be desirable to know how rock properties influence breakage. At present, rock properties directly- related to fragmentation are undefined. Although present testing technology- does not permit rigorous definition of in-situ rock fragmentation behavior, several properties (mechanical and physical) commonly are used to indicate the relative case with which rock breaks. The more common test is for uniaxial compressive or tensile strength of cylindrical cores taken from intact portions of the in-situ rock (testing details are provided ill Sec. 6.2, Rock Mechanics). The strength of rock is influenced by the environmental conditions imposed on the rock. Those of most importance in rock are (1) confining pressure. (2) pore fluid pressure, (3) temperature and (4) rate of load application. Increase in confining pressure, as with increasing depth beneath the earth's surface or under the action of a fragmentation tool, causes an increase in rock strength. Increases from atmospheric pressure to 10.000 psi commonly cause up to n fourfold increase in the compressive strength of crystalline rock. Apparent rock strength decreases as pore fluid pressure increases, since it decreases the effect of confining pressure. The effective stress concept of soil mechanics generally applies to rock. Although chemical effects of pore fluids influence rock strength, they geologically are small compared to the confining pressure effect, except for a small minority of rock types. Increase in rock temperature causes a decrease in rock strength. This effect

Jan 1, 1973

By Wendell H. Wiser

A comparison is presented of coal pyrolysis at temp¬eratures ranging from 4090 to 497°C and thermal dissolution of coal in tetralin at temperatures ranging from 350° to 450,°C, both utilizing a Utah high-volatile bituminous coal. The initial coal pyrolysis reactions are second order with an enthalpy of activation of 35.6 kcal per mole. The fraction of total product yield produced under second order conditions ranges from 67% at 409°C to 96% at 497°C. The process then gradually deteriorates to a first order reaction in the later stages with enthalpy of activation of 4.1 kcal, per mole. The initial reactions of solution of coal in tetralin are second order with an enthalpy of activation of 28.8 kcal per mole. The fraction of total product produced under second order conditions ranges from 63% at 350°C' to 94% at 450°C. The dissolution process then gradually changes to first order in the later stages with enthalpy of activation of 15.6 kcal per mole. A model is presented which relates the two processes and explains, the significance of the above similarities.

Jan 1, 1967

By Robert M. Lewis

Chemically, mica is a complex silicate of sodium, potassium and aluminum. There are no important uses of mica where the chemical analysis is important, except that in some uses of ground mica, the content of iron oxide present as an impurity must be kept to a very low limit. Muscovite mica is frequently found containing black and red "stain" as a homogeneous part of the books or sheets. In most cases this stain or impurity is magnetite or hematite. Some mica contains impurities deposited by infiltration. This is commonly a red stain, less often brown or white. The best mica is free from all such impurities, and the greater their content, the less value does the mica have.(1) It is because of these undesirable impurities that a large segment of the fine ground mica industry relies on weathered pegmatites and alaskite ores as a source of raw material. The mica concentrates obtained from these ores are relatively clean and require moderate beneficiation to meet color and density specifications. One need only to observe the stained and decrepitated condition of the mica recovered from mica schist to appreciate the challenge that processing this material presents. Despite these adversities there are several advantages to be gained by mining and processing mica schist ores. The mica content of these ores are considerably higher than the pegmatites and alaskite ores now being mined, often containing in excess of forty percent mica. This-higher grade mica feed should promote a lower mining and milling cost with its resulting competative advantage. With more rigid government

Jan 1, 1969

By J. J. Scott

Friction Rock Stabilizers, trade name Split Set*, is a new support system invented by the author and under development by Ingersoll-Rand and Lee-Norse Company. Split Sets are a substitute for standard bolts or fully grouted resin bolts and have certain advantages which are: 1. Improved safety for the miner 2. A rational design is possible based on rock mechanics principles 3. Supports can be made either to be yieldable or rigid 4. Supports can be used to build a roof beam or to suspend roof material 5. It is cheaper than the resin system and costs about the same as standard bolts.

Jan 1, 1974

By P. Bartel

Coal cleaning can be effected by the bacterium Sulfolobus acidocaldarius, which in oxidizing sulfur and dissolving mineral matter requires carbon dioxide and oxygen; carbon dioxide as a carbon source and oxygen as an electron acceptor. The desulfurization of coal by thermophilic bacteria under elevated partial pressures of carbon dioxide and oxygen was studied at a total pressure of 1 atm. The partial pressure of carbon dioxide was varied over the range 0.00032 to 0.33 atm (0.00032, 0.007, 0.10, 0.33 atm), and the partial pressure of oxygen was varied over the range 0.14 to 0.40 atm (0.14, 0.21, 0.30, 0.40 atm). The maximum rate of coal desulfurization increased by 32%, from 9.0 to 11.9 mg S/1 hr, as air was enriched in carbon dioxide from its atmospheric level of 0.00032 atm to 0.10 atm. Enrichment with carbon dioxide up to 0.10 atm, at constant oxygen partial pressures, increased the desulfurization rate, but enrichment to 0.33 atm caused the rate to decrease. At constant carbon dioxide partial pressures, the desulfurization rate was maximum at oxygen partial pressures of 0.21 and 0.30 atm. At higher (0.40 atm) and lower (0.14 atm) oxygen partial pressures the rate decreaed by 9 to 20%. The desulfurization rate decreased by 58X, from 9.0 to 3.8 mg S/1 hr, when the air pressure was increased from 1 atm to 3 atm. The effects justify an economic analysis during design and operation of a commercial air feed in a process to desulfurize coal by microbial action.

Jan 1, 1986

By Don Muraoka

Soda ash, anhydrous sodium carbonate, is produced from underground trona deposits occurring in the Green River Sasin of Southwestern Wyoming. Stauffer Chemical Company of Wyoming, a jointly owned subsidiary of Stauffer Chemical Company and Rocky Mountain Energy Company mines the trona and processes it into high-purity soda ash. Stauffer Wyoming has been in operation since 1962 with a current production capacity of approximately 2.2 million tonnes (2 million short tons) per year of soda ash. The Refinery has five parallel operating trains utilizing the monohydrate process which is a series of chemical processing unit operations described below. Screening and Crushing the Trona The mined trona is brought to the surface in two counterbalancing ore skips. The ore is initially screened with Refinery feed, less than peagravel size material, entering the process while the oversize is conveyed to an outdoor stockpile.

Jan 1, 1984

By Marcel Michaud

Over the past five years, the two-fold growth in Canada's coal industry "Figure, 1" results primarily from the coking coal market to Japan and, to a lesser degree, by the increasing use of sub-bituminous and lignite coal for power generation in the Prairie Provinces. This expansion will continue, but production of coal for domestic thermal generation of electricity will grow at a faster rate than coking coal exports "Figure, 2". Half of the 20 million tons of thermal coal used for electrical power generation in Canada during 1974 were imported by Ontario Hydro from U.S. coal companies in West Virginia and Pennsylvania. Ontario Hydro's Nanticoke station on Lake Erie which will consume 7.5 million tons of coal in 1977 when fully operative, as well as other future planned projects, could cause Ontario Hydro's coal consumption to rise from 10 million tons today to 20 to 25 million tons by 1985

Jan 1, 1975

By Robert E. Goodwin

There are four main requirements which must be considered when selecting a wire rope for the best serviceability. A proper choice is made by correctly estimating the relative importance of each of these requirements and selecting s rope which has those qualities best suited to withstand the combination of destructive forces expected under continued service. A wire rope should possess: 1. Strength sufficient to support the maximum load expected and with s proper safety factor. 2. Ability to withstand bending and to resist bending fatigue without failure of the wires. 3. Ability to withstand surface abuse such so abrasive wear, pounding, and wire scrubbing. 4. Ability to withstand abuse such as crushing and distortion.

Jan 1, 1968

By Armando M. Lago

This paper reviews the postwar changes that have occurred in the expenditure and financial behavior of mineral corporations, and in particular the relative importance of factors that affect the industry's supply and demand for funds. This quantitative statistical investigation of factors affecting sources and uses of funds of mineral corporations is achieved through the formulation of a simultaneous equation model of sources and uses of funds. After a description of the study sample in Section I, the postwar cyclical and secular financial behavior of mineral corporations is analyzed in detail in Section II. Section III formulates an econometric model of mineral corporate financial behavior which is then estimated and reviewed in Section IV. Section V discusses policy issues regarding depletion allowances, investment tax credits, and industrial organization of the mineral sector. Finally, the optimum financial structure of mining firms is discussed in Section VI, which analyzes the effect of corporate financial structure on the mining corporations' average Cost of capital.

Jan 1, 1969

By T. Szwilski

The Appalachian coal region is an area here the small mining operation dominates. The large number of small operations makes the coal industry in chat area very competitive, the industry concentration ratio being low. This feature is reflected in the nature and behavior of the coal supply and demand viz a viz the coal market. The vast majority of the small coal operations in Eastern Kentucky for example, are contractors. The circumstances under which a large mining company can elect to use contractors to supplement their coal production are examined. The pros and cons of small underground single unit mines and larger multiple unit mines are discussed.

Jan 1, 1986

By Scott G. Britton

Planning is a management tool used to solve problems and provide data and decision alternatives for company growth, profitability, and direction. Strategic planning is defined as the efforts needed to accurately measure the risks of obtaining a result from future actions given a finite number of outcomes. The techniques of strategic planning are being applied more and more to underground mine design as a result of the fierce market conditions underwhich the industry is facing today, and the conditions they will likely face in the future. The objectives of strategic planning are centered on the ability of the operator or company to manuever its limited resources to the best position available under the given future scenarios. This paper briefly examines the most popular techniques for accomplishing these objectives, how these techniques fit into the current mine management decision-making, and what results to expect from these techniques in planning efficient underground mines.

Jan 1, 1985

By P. W. Erickson

Development of the Twin Buttes mine entailed the largest known preproduction stripping job in the history of mining. It linked earthmovers and conveyor belts in a new approach to development of a pit that may reach, or even exceed, dimensions of 1 x 1-1/2 miles at the surface and go as deep as 1800 feet. The orebody to be stripped was covered by an average of 460 feet of alluvial gravels, which presented an initial stripping job of great magnitude. The initial pit layout and the original time schedule established early in 1965 called for the excavation and disposal of about 250,000,000 tons of alluvial overburden before the end of 1969. Allowing about a year for equipment delivery, this schedule left four years to do the job averaging about 62-1/2 million tons per year. In 1964 when The Anaconda Company undertook the development of Twin Buttes, it was recognized that special planning was necessary for the disposal of waste material and tailings. Environ- mental control was a prime consideration and is particularly sensitive in the Twin Buttes area due to the proximity to residential developments. Disposal of the 250,000,000 tons of alluvium, as well as future rock and tailing waste material, presented a problem which Anaconda engineers resolved by designing a plan to spread out much of the alluvium over an extended area, including a massive 11- 1/2 mile dike system which will impound mill tailing in three basins. The tailing will be impounded behind these-dikes to avoid wind exposure and blowing. The dikes also serve as a

Jan 1, 1974