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By P. K. Muduli

The number and the type of trucks and shovels are two important factors in determining the optimal design parameters of an open-pit mining system. Characteristics of trucks' arrival and service-time distributions determine the performance measures of a truck-shovel system when it is modeled as a closed queuing network. In all of the previous analytical queuing studies of truck-shovel systems, trucks are assumed to be identical with respect to their arrival and service-time distributions. This assumption, although desirable for reducing computational difficulties, causes either underestimation or overestimation of the performance measures depending on the number and type of equipment used in the model. The relative error in performance measures could be significant when the number of different types of trucks and shovels is large. In this paper an analytical method is proposed to model the truck-shovel system as a multiple-chain closed queuing network. This approach would provide the capability of estimating system performance measures for planning purposes when the truck fleet is not necessarily composed of identical trucks. An example of truck-shovel systems is discussed to show how the incorporation of different types of trucks does affect performance measures.

Jan 1, 1996

By A. E. Petersen

The United States Bureau of Mines conducted research on high-intensity magnetic separation methods for upgrading tantalum concentrates from Alabama. Process flow sheets were studied to maximize tin removal and minimize tantalum loss. Using laboratory-scale equipment, concentrates were produced which contained over 65% combined Ta2O5-Nb2O5. Up to 78% of the tin was recovered as a byproduct, containing about 70% SnO2. Only 1 to 5% of the tantalum reported with the tin byproduct. The producer subsequently incorporated high-intensity magnetic separation into its process flow sheet to provide concentrates for the National Defense Stockpile.

Jan 1, 1993

By Thomas J. Neil, O&apos

Mine land reclamation is a comparatively new science-Although some mining companies point with pride to reclamation efforts of 20 to 30 years ago these were the exception rather than the rule. In the last ten years the skyrocket of environmental awareness has been awesome to behold. Future shock gripped mine operators everywhere as they struggled to cope with rapidly changing and escalating demands. The initial result was that two divergent points of view became dominant. Environmentalists said, "Put it back the way it was," and the miners responded, "Let's grow some weeds and hide it." These views are not surprising as they represent rather obvious alternative responses, albeit at opposite ends of the decision spectrum. The former case has prevailed more often than the latter, as most state and federal legislation -- both proposed and passed -- has required drastic alteration of the post-mining landscape so that evidence of prior mining is largely obliterated. An exception to this has been in porphyry copper country where the infrequent abandonment of mines has given emphasis to the second philosophy -establishing vegetative cover on mine waste materials. Now, it should come as no revelation to most mining people that both of these approaches to mine reclamation suffer from serious drawbacks when applied to open pit copper mines. First, whereas waste dumps and tailings dams can be vegetated with some aesthetic benefit, the massive presence of copper mining operations remains very prominent. It is difficult to conceal an open pit copper mine. Second, returning open pit copper mines lands to their original topography and productivity is simply not a reasonable alternative.

Jan 1, 1976

By Miroslav Cervenka

The Coal, characterized by coal quality parameters as for example, ash content (Ad), moisture (Wrt), heat content (Qr1), sulphur content (Sd) and other parameters is still in many countries the basic source of energy. Energy is life, especially in modern society, where the demand for ecologically clean energy is very high; and therefore, there is great importance in effective coal utilization Direct utilization - burning of coal for energy generation, is still one of the most effective methods. In most cases, it is one of the cheapest energy transformation methods in spite of the fact that this energy transformation is connected with the deterioration of our surroundings. Deterioration can be substantially reduced if the burning of coal at power stations, heat power stations and other coal consumers is optimized. That means the burning is done in steam boilers, the technical state of which is very good; the coal has minimimum .variations with respect to the projected values; and the burning process is controlled and checked not only from a regulation point-of-view but also from an ecological point-of-view. The instrumentation capable of measuring the characteristic coal quality parameters in real time exists and it forms the basic assumption for the work our research team has made. The proper application of this instrumentation is able to provide information for burning process optimalization. It is the main topic of this paper, which is the compilation of the information on our work -made during the last five years. The whole information is based on practical experience and applied systems in Czechoslovakia in the mines and power engineering industry. See [Cervenka, 1989]

Jan 1, 1992

By Marion A. Goudie

The Devonian salt basin, which contains the Saskatchewan Potash deposits, extends from just east of the foothills in Alberta, north as far as the Peace River area, across Saskatchewan and into Manitoba as far east as Range 10 west of the First Meridian and south into Montana and North Dakota. The basin is closed everywhere except to the northwest. The known potash deposits are confined almost entirely to the Province of Saskatchewan, with the exception of a small area in western Manitoba bordering the Saskatchewan boundary. The following discussion will concern only the Saskatchewan part of the basin. The evaporite series in the basin is defined as the Prairie Evaporite Formation of the Elk Point Group, of Middle Devonian age. Recent work done by potassium-argon dating methods has indicated an Upper Middle Devonian (Givetian) age of from 265 to 347 million years for the potash. The Elk Point Group consists in ascending order of the Ashern, Winnipegosis and Prairie Evaporite Formations. The Ashern formation, sometimes called the Third Red Bed, consists of dolomitic shales or shaly dolomites. The Winnipegosis is a reef type dolomite, usually with good porosity, and in many cases oil-staining, although to date no production has been obtained. The Prairie Evaporite formation consists of anhydrite overlain by halite and finally, in Saskatchewan, by the potash beds. In almost all wells which have been cored for potash the lowest potash bed is underlain by one or two bands of anhydrtte, which are used as marker horizons. Cores from a few wells which cored to the bottom of the salt series have shown flecks of potash throughout the halite.

Jan 1, 1959

By W. R. Hail

A proactive design and construct approach was used to remediate the Warm Springs Ponds Complex near Anaconda, Montana under "Superfund". The pond complex is used for treatment/settlement of heavy metals and is a repository for 19,000,000 cubic yards of tailings, precipitates and associated sediments. Remediation has resulted in treatment/settling capacity for flows up to the 100-year flood (3,300 cfs); expansion from 5 to 11 ponds in series requiring 12.5 miles of new or improved embankments with associated hydraulic structures; flood protection for the 0.5 Probable Maximum -Flood (PMF) (70,000 cfs); and closure of exposed tailings along with aquatic and terrestrial habitat enhancement.

Jan 1, 1995

By Julian Malnic

The nascent marine mining sector appears to be now at a point of critical mass with the prospect of mining seafloor massive sulphide deposits at some time in the coming few years an inevitability. Julian Malnic makes comments from his experience base as an entrepreneur and founder of Nautilus Minerals Inc. in 1995 and will speak from an independent viewpoint of the commercial setting of the status quo of the proto-industry and the major factors likely to have major influence over its future. The presentation questions these factors and the role they will play. Do we need metals from the oceans? Understanding the competing and established terrestrial sources of each commodity is essential in comprehending how a marine competitor can profit. What are the rates of discovery for marine minerals? At what point will marine explorers start to impact the terrestrial copper and zinc exploration sector? The advance of technology is important in finding, imaging and mining SMS deposits, but which new technologies offer the advantage to mining in the ocean and which to mining on the land? Several competitors have now joined Nautilus as competitors to this global pioneer of SMS exploration/production. The membership of the major miners in the marine sector is growing steadily with important relationships developing but many have not put a toe in the water yet. A path of increasing width is opening to commercialization of SMS miners but crusts and nodules, as bearers of copper ? also found in SMS, and nickel ? also found in widespread nickel laterite deposits on land, are unlikely, in this perspective, to be winners this century unless highly valued minor metals are targeted.

Jan 1, 2008

By Hal McVey

Introduction The role of marketing in the minerals and mining industry takes on different degrees of importance depending on the commodity, but nowhere are sales and marketing more important than in industrial minerals. This article compares industrial minerals marketing with the marketing of other mining and mineral products. Marketing in Mining Some broad generalizations on the marketing of industrial minerals in relation to other mineral products can be made without getting bogged down with exceptions to generalizations. Two totally different areas of mineral production are crude oil and natural gas, and metals, including ores and concentrates. Although these commodities are the basis for two completely different industries, they share two things in common from a marketing standpoint: • Their value per unit volume is usually high enough so that they can be transported great distances. • Their specifications are readily definable and, therefore, the quality of a standard product from a production run can be communicated by stating certain chemical and physical features. This permits sales to be consummated by telephone, telex, and letter, without the need to pretest the products under use conditions. In regard to the first item, industrial minerals, as opposed to oil, gas, and metals, are in most instances site specific. Location of the point of production in relation to the point of use is of paramount importance based on a generally lower unit to volume value. This means that transportation is a major factor, with the cost of getting the mineral to market commonly exceeding its f.o.b. value. Coal marketing has many characteristics in common with industrial minerals. Coal sales can es-

Jan 11, 1983

By Carl F. Austin

The subject of strata control in mining can be approached from both static or loading concepts or from dynamic or impulsive loading concepts. The fracture process itself appears to be primarily a dynamic process as is the gross creation of fractures through the use of impact, stress wave passage or in more general terms, the use of explosives. This paper presents experimental results which indicate that the understanding of the fracture behavior of rock that has been, established in the open literature is not always appropriate. In particular, the results of this experimental program have shown very interesting differences between the formation of fractures in rock and the formation of fractures in other materials such as metals and plastics which are often used as models for rock behavior studies Fracture patterns and causes of dynamic fracturing in various rock and artificial materials are presented.

Jan 1, 1965

By Jeremy Cawley, Jeff Murphy, Horry Parker, Brock Gaspar, Jake Keegan

The Lower Olentangy Tunnel project includes 47,000 cubic yards of planned ground improvement for earth pressure balance machine (EPBM) tunneling (5.2 km) and microtunneling (335 m) in glacial soils. Jet grouting started in late 2021 and will continue through 2023 to complete operations at 5 shafts, 14 safe havens, 5 watermain ground improvement zones, and a river crossing. Typical jet grout columns are installed at depths between 15–24 meters. Discrete soil-cement blocks range from 267–8,900 cubic yards in volume. This paper discusses the methodology, testing, and technical considerations associated with jet grouting operations in glacial overburden across an urban environment.

Jun 13, 2023

By Y. Q. Lu

Efficient flotation of fine phosphate minerals from a deslimed waste phosphate stream (-74 microns) has been achieved by both bench-scale flotation and by flotation with a 2-inch air-sparged hydrocyclone (ASH) unit. A sample was collected from the waste phosphate slime stream at the SF Phosphate Limited Operations near Vernal, Utah, for flotation experiments at University of Utah laboratories. The collector used was a mixture of fatty acid, petroleum sulfonate and kerosene. Bench-scale flotation test results show that the minus 15-micron particles have a significant adverse effect on phosphate flotation. When the minus 15-micron material was removed by a classifying hydrocyclone, improved flotation recovery and concentrate grade were realized. A bench-scale flotation recovery of 86 % with a concentrate grade of 16% P2O5 was obtained from classified waste slime (74 x 15 microns) feed material containing 11.3% P2O5 In contrast, a 90% P2O5 recovery was achieved with a concentrate grade of 16-18% P2O5 by single-stage ASH flotation. With a second stage of ASH flotation, a concentrate containing 23% P2O5 was realized at an overall recovery of 75%. These results indicate that the industrial application of ASH flotation technology for phosphate recovery from waste slimes is promising.

Jan 1, 1995

By Alissa Lockett, Chris D. Breeds

Central Water Integration Project (CWIP) Segment 5-1 is the most critical segment of a regional water supply project that transfers groundwater from Burleson County to northern San Antonio, replacing over 20% of that City’s water supply with a new source. CWIP Segment 5-1 included three tunnel reaches totaling 10,350-ft and 5 shafts that were constructed inside the City in an area known to contain large karst features. This paper describes site work used to investigate the alignment for karst features, manage potential environmental impacts, develop the contract package required for mitigation and the means and methods used to mitigate the large karst features that were encountered.

Dec 1, 2022

By Donna L. Boreck

Introduction Coal has been mined in the western United States since the mid-1800s. The resource is abundant in the West. Despite recent economic conditions, it remains an important part of the nation's energy warehouse. Many of the seams that comprise the western resource base are thick, some exceeding 61 m (200 ft). Multiple, closely-spaced seams or thick coals that split into two or more minable seams are also common. Historically, subsurface development recovered from less than 15% to 50% of these deposits (Matson and White, 1975). This resulted in a substantial loss of inplace reserve due to the limited height that could be mined using the available technology. In an effort to increase future recovery from such deposits, the US Bureau of Mines analyzed the potential for incorporating three thick-seam mining methods into western coal mines. These methods are high-face longwall, multislice longwall, and longwall caving. They were developed in Europe and are being used to mine thick coal seams in Europe and Asia. One aspect that will determine their success in the US is the geology of the individual deposit; namely, are the methods adaptable to the geologic conditions characteristic of western coal? This paper analyzes some of the geologic factors that would affect development of thick or closely-spaced seams using these mining methods. Occurrence of thick and closely-spaced seams Since mining conditions and methods differ around the world, a thick seam is often defined as a seam whose total thickness cannot be extracted using the available equipment. In the western US, the maximum extractable mining height is about 4.3 m (14 ft). For this research, a thick seam was defined as a minable seam 4.6 m (15 ft) thick or more. Since one of the seams is usually lost using standard mining methods, closely-spaced or split seams were also addressed. These were defined as two minable seams 1.5 m (5 ft) thick or more separated by 9 m (30 ft) of interburden. Thick or closely-spaced coal seams are common in the West. Their importance has not been documented due, in part, to the methods used to measure resources. In the past, all reserves greater than 1.1 m (42 in.) thick for bituminous seams and greater than 3 m (10 ft) thick for subbituminous seams were grouped together and were differentiated only by rank. Further differentiation by seam thickness or minability was not done. For this reason, reserve figures for thick or split seams are difficult to determine. By analyzing available published resource data, Ferm and Muthig (1982) addressed thick seam resources. They estimated a resource of 90 Gt (99 billion st) of coal (16% of the Western resource base) in seams 4.6 (15 ft) or greater at less than 610 m (2000 ft) overburden. Yet, a later study of Pierce and others (1982) on one thick seam deposit in the Powder River Basin estimated a resource of 103 Gt (113 billion st). Pierce (1986) reported that the overburden reached a maximum of 731 m (2400 ft). The resources in this single deposit exceeded the 90 Gt (99 billion st) total projected for the entire western US by 12.7 Gt (14 billion st). Due to such differences, this author chose to look at reported occurrences of thick or closely-spaced minable seams in place of resource figures, to verify the need to research thick seam mining in the West. An occurrence was defined as an isolated site where a thick seam or two or more closely-spaced seams were reported. The occurrences were derived from published material - mostly mine descriptions, measured sections, coal exploration logs, and oil and gas logs. Due to time constraints, the reserves associated with each occurrence were not determined. All data points were random. The analysis was limited to occurrences in Colorado, Wyoming, and Utah. Although source material available to the author was limited to general coal summa-

Jan 3, 1988

By David M. Stearns

Introduction Millions of tons of coal are shipped by rail each year in the US. Loading those trains efficiently is a topic being studied by coal producers and railroads. Alternatives range from volumetric loadouts to systems that weigh the product, using either belt conveyor scales, track scales, or weighbins. Each system has its proper application and each has pros and cons, depending on the volume, nature, and layout of the specific loading facility. In recent years, a batch weighing system has been developed that offers significant benefits to higher volume operations shipping by a unit train. The Unitrain Loadout System (ULS) features a precision electronic batch weighing system married to a mechanical loadout system by a microprocessor-based digital control system. A batch weighing loadout could be designed using analog electronics or even a mechanical weighbin. But it is the adaption and use of a microprocessor that provides the primary benefits of a unit train loading facility. Those benefits are accurate weight determination, optimum car use, overload prevention, speed in loading, optimum labor use, and documentation of the loading process. Unitrain History The first ULS was erected for iron ore applications in Canada during the 1960s. The first domestic system on coal was installed at Pittsburg and Midway Coal Co.'s McKinley mine at Gallup, NM, in 1978. At present, there are more than 20 Unitrain Loadout Systems in operation worldwide. They are loading minerals, concentrates, and coal. Eleven systems are presently in service or under construction in the US. In the last several years, a number of comparable systems have also been installed. As a result, the concept has been well proven and is now commercially available from several sources. Unitrain Operation The basic operation of a ULS involves loading a unit train with individually weighed batches of coal while it moves slowly under a loadout tower. Typical coal systems are designed to load at rates of 2.7 to 6.3 kt/h (3000 to 7000 stph). The contents of each car can be accurately weighed. This meets the requirements of the National Bureau of Standards Handbook No. 44 for static weighing. Also, cars can be loaded within very close tolerances. This optimizes railcar usage and prevents overloads. Principal components of the loadout system are the main feed conveyor, the surge bin, surge bin gates, weighbin, weighbin gate, flood loading chute, control room, calibration weights, and hydraulic and electrical systems (Fig. 1). Main feed conveyor: Coal is delivered from a storage area by the main feed conveyor. The conveyor fills the surge bin. It should be capable of conveying coal at the same rate at which it is being loaded. Usually the feed conveyor is equipped with a conveyor scale that can display rate in the control room and control feed to the belt. The surge bin will typically store 227 to 272 t (250 to 300 st) of coal. If the loadout is installed in an over-the-track silo, there is no need for a surge bin. Four double-bladed, hydraulically actuated gates are incorporated into the bottom of the surge bin. These gates open to fill the weighbin. Automatic pre-act points are selected by the control system. They shut these gates as the desired weight is approached. The final amount of coal is added by a single gate that closes. This results in a weighed batch of coal within ± 0.5% of the selected optimum load per railcar. Thus, if loading 91-t (100-st) capacity cars, the system is set to batch up 90.2 t (99.5 st) batches. Each car is expected to be loaded between 90 and 91 t (99 and 100 st). Weighbin: The weighbin is next in the flow scheme. Typically, it is

Jan 3, 1985

By Ralph J. Holmes

INTRODUCTION Although sampling techniques used by the mineral industry continue to improve, sampling is still an area which is often neglected. Frequently, sampling and sample preparation requirements are left to personnel who do not fully appreciate the significance and importance of sampling. Consequently, plant evaluations are often based on seriously biased samples, leading to mass balance problems and incorrect assessments of plant performance. The basic rule for correct sampling is that each particle of ore or concentrate must have an equal probability of being collected and becoming part of the final sample for analysis. If this is not the case, bias is easily introduced and the sample is not representative. For example, when ore is travelling on a conveyor belt, the lumps may come to the surface. Consequently, a grab sample taken from the top layers only will contain a greater proportion of lumps, i.e., the sample is biased. There seems little point in making major investments in precise analytical equipment, if the sample provided to the analytical laboratory is not representative in the first place. This paper describes the sources of plant sampling errors, reviews the methods of estimating their variance, presents some worked examples, and provides some practical advice for reducing sampling errors and their variance. SAMPLING BASICS It is generally accepted that the discharge point of an ore or concentrate stream is the most suitable sampling location. The stream can be intersected at regular intervals, and representative samples, referred to as increments, can be obtained by taking a complete cross-section of the ore stream. On the other hand, sampling devices that take part of the stream on an intermittent or continuous basis, e.g., a bleed from a pipe, may introduce serious bias, and should be avoided at all cost. Increments may be taken at completely random times or tonnages during the sampling operation, in which case it is called "random sampling". However, as shown below, random sampling results in the largest sampling variance, so it is preferable to divide the ore or concentrate stream up into strata of equal time or mass and take one increment from each stratum. This operation is called stratified sampling and may be either systematic sampling, in which increments are taken at the same point in each stratum, or stratified random sampling in which the increments are taken at random within each stratum. Systematic sampling results in the smallest sampling variance, provided periodic variations in quality or quantity are not present which may coincide with, or approximate to, any multiples of the proposed sampling interval. In such cases, it is strongly recommended that stratified random sampling within fixed time or mass intervals be carried out.

Jan 1, 1991

By Peter T. Luckie, Joseph W. III Leonard

INTRODUCTION In a bed of fine coal, water can be found in the interstices created by the particle surfaces and in the pores within the coal particles. The extent of the interstices voidage is obviously a function of the particle sizes and morphologies, as shown by the fact that the bulk density of coarse coal is greater than that of fine coal. After drainage, the voids can be completely or partially filled. By increasing the suction pressure across the bed, as is done in vacuum filtering, the quantity of water in the voids can be reduced. But eventually the increased suction pressure has little influence on the moisture reduction. In addition, the moisture in the pore structure of the coal is unaffected by the mechanical removal of the moisture in the interstices. When this condition is reached, the total moisture content of the coal can only be reduced further by evaporating the water. Evaporative drying is done for one or more of the following reasons: 1. To avoid freezing difficulties and to facilitate handling during shipment, storage, and transfer to the points of utilization. 2. To reduce the heat loss due to evaporation of the moisture from the coal during the combustion process, thus increasing heating efficiency. 3. To decrease transportation costs. The heating value of coal is equally improved for each percentage point reduction in the noncombustibles in coal. It is estimated that a reduction of 1%22 in the total moisture in the coal increases the thermal efficiency of the heat-raising process by about 0. Some coal buyers consider 1 % moisture content to be the equivalent of a 4% ash content.23 It is important to avoid drying the coal to too low a moisture level, since the complete removal of surface moisture to produce a bone dry product can result in a serious dust, wind lost, and safety problem. Surface moisture con- tents of 3% or less for shipped coal are not uncommon. However, the evaporatively dried coal may be lower, Y, to 1%, since the mechanically dewatered coal may be higher. Evaporatively dried coal can be treated (sprayed) with chemicals in order to control the dustiness and any freezing difficulties, thereby providing the producer with more operational flexibility. The evaporative drying of coal is essentially a process of simultaneous transfer of energy, usually in the form of heat, and water, in the form of vapor, from the coal. In order to remove the undesired moisture, it is necessary to raise the temperature of the water from the entering temperature of the feed stream, TF, to the boiling point of the water (usually taken as 212"F), vaporize

Jan 1, 1991

By R. C. Schmidt

The Mont Klahoyo magnetite deposit is located about 600 km northwest of Abidjan, Ivory Coast. During an exploration period ending in 1977 an international joint venture group investigated the deposit and proved reserves of 670 million tons grading 36% iron. The deposit, occurring at the northeast end of the Baoubly-Kiriao chain of Precambrian iron formations, is associated with amphibolites, pyroxenites and gneisses of the Liberian Shield. At Mont Klahoyo occur two separate iron formations of which the lower member is the ore body. This lower member consists of a highly metamorphosed - banded quartz-magnetite iron formation in which iron silicate bands alternate with beds of quartz-magnetite. mphibolite-pyroxenites and sillimanite-cordierite-garnet gneisses form hanging and footwall rocks. The iron formation has been folded into an elongated overturned "Z" shaped major drag fold with axes trending and plunging approximately northeast. Beds are vertical or dip steeply to the southeast. The ore zone has an average thickness of 130 m and outcrops intermittently over a distance of approximately 5.5 km. Based upon detailed studies of drill cores and the results of ore dressing test work, eight stratigraphic units, identified as K-1 to K-8, are recognizable in the iron formation. Four interbedded units are low grade silicate zones (silicate facies) with the remaining quartz-magnetite units (oxide facies) repre¬senting the important ore zones of the Mont Klahoyo deposit. The ore-bearing "K" units are subdivided further, based upon their specific lithologies, iron content and concentration characteristics, into eleven ore types. The identification of these ore types is considered particularly important to mine planning and flowsheet design. A cap of oxidized materials overlies the primary quartz-magnetite iron formation but no enrichment has occurred. It is proposed that the Mont Kalhoyo iron formations were deposited, possibly chemically, in a volcanic environment as a siliceous iron formation with volcanism providing the primary source of iron and silica. Metamorphism converted the siliceous iron formation to a relatively coarse-grained quartz-magnetite-silicate iron formation.

Jan 1, 1979

By J. Wagner, P. Eger, G. Melchert

In 1991, LTV Steel Mining decided to close an open-pit taconite mine in northeastern Minnesota using a passive-treatment approach consisting of limiting infiltration into the stockpiles and wetland treatment to remove metals. More than 50 Aft (55 million st) of sulfide-containing waste had been stockpiled adjacent to the mine during its 30 years of operation. Drainage from the stockpiles contained elevated levels of copper, nickel, cobalt and zinc. Nickel is the major trace metal in the drainages. Before the closure, the annual median concentrations ranged from 1.5 to 50 mg/L. Copper, cobalt and zinc are also present but they are generally less than 5% of the nickel values. Median pH levels range from 5 to 7.5, but most of the stockpile drainages have pH levels greater than 6.5. Based on the chemical composition of each stockpile, a cover material was selected. The higher the potential that a stockpile had to produce acid drainage, the lower the permeability of the capping material required Covers ranged from overburden soil removed at the mine to a flexible plastic liner. Predictions of the reduction in infiltration ranged from 40% for the native soil to more than 90% for the plastic liner. Five constructed wetlands have been installed since 1992. They have removed 60% to 90% of the nickel in the drainages. Total capital costs for all the infiltration reduction and wetlands exceeded $6.5 million, but maintenance costs are less than 1 % of those for an active treatment plant. Because mine-drainage problems can continue for more than 100 years, the lower annual operating costs should pay for the construction of the wetland-treatment systems within seven years.

Jan 1, 2000

By Bernhard C. Koch, Richard W. Hutchinson, Bernhard Free

The Tertiary Silverton caldera collapsed asymmetrically to the southwest 27.5 m.y. ago. Resurgent volcanic activity is expressed by a quartz-monzonite stock at the southern caldera margin and by the Red Mountain porphyry stock in the northwest of the caldera which were emplaced at 25 m.y. and 11 m.y. b.p., respectively. The apical Eureka graben formed between 27.5-22.5 m.y. ago and transects the Silverton caldera southwestward. In the northeast it terminates at the 22.5 m.y. Lake City caldera margin. This graben as well as caldera faults provide dominant structural control for base and precious metal deposits. The epithermal gold mineralization of the Gold King mine is proximal to the Red Mountain stock in the north central part of the caldera. Here, west-northwest striking faults related to the collapse of the caldera intersect northeast faults of the Eureka graben. Superimposed upon earlier base metal mineralization at 23 to 22.5 m.y. b.p., the 11 m.y. younger gold metallization was a distinct event at Gold King. Supergene enrichment of the hypogene precious metal assemblage resulted in a metal tenor of up to 3,016 g/t gold and 1,088 g/t silver. The deposit is hosted by quartz-latite tuffs, flows, and flow breccias of the Burns Formation. Veins, up to 5 m wide follow steeply southeast and northwest dipping structures of the Eureka graben. Subsidiary veins up to 2 m wide branch off the main lode and are termed "flat veins" because of their conformable strike but shallow dip of 45' to 50' toward the northwest. Meteoric water-dominated hydrothermal solutions generated by the Red Mountain stock ascended through intensely fractured, ferruginous

Jan 1, 1988

By R. L. Hills

America's industry uses about 44% of the total energy consumed by the nation directly as fuel burned in industrial plants or indirectly as fuel burned by utilities to provide electric power. In addition, industry requires raw materials or feed stocks derived from fuel sources or having fuel value. This represents about 11% of total U. S. energy consumption, bringing industry's portion to about 55%. Adding that portion of energy consumption required by the transportation sector to move raw materials, intermediates, and finished products, the total energy impact of industry approaches 213 of total U. S. consumption. It is obvious that American industry has the largest share in the task of balancing energy demand and supply. What are we going to do? -- We must increase the supply of energy and increase the beneficial results obtained from each unit expended. Both avenues, unfortunately, are limited in extent and speed. Increases in supply cannot occur without drastic and permanent increases in cost. These increases in cost are un- desirable and inflationary but do provide incentive for the rational businessman to expend the effort and money required to improve the effectiveness of energy in industry.

Jan 1, 1975