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General. Data for the operating information given in the 15 tables in this chapter was obtained from voluminous questionnaires sent to over 100 operating companies in 1972. There has been a considera¬ble change since then in supply and power costs and many companies have had expansions or revisions since that time, so it must be realized that information is valid for the year 1972. This is true except for the three new properties of Sacaton, Metcalf, and Pinto Valley. These three operations started up since 1972 and all information for them was obtained in 1975. The questionnaires were sent to all major copper properties throughout the world as well as to many smaller units and to some mines that had complex or unusual conditions. Properties for which no information is given did not submit completed questionnaires. Several operations were unable to supply information requested be¬cause of company policy prohibiting it. However, data is presented for 75 different operating properties. The reference number of the left-hand column is the same for all 15 tables of data. If the company had several operating properties as of 1972, then subsequent properties use the same number but a different letter. For example, Anaconda's property at Butte, Mont., is IA, whereas Anaconda's (now Anamax) Twin Buttes property in Arizona is IB. Table I gives general data for the properties including exact loca¬tion, milling rate, pertinent assay values and recoveries, and a brief listing of ore and gangue minerals. It was not possible to obtain any more information from the properties in Chile except that given in Table I. Crushing. Crushing plant operating data is given in Table 2. This table gives data on the crushers, feeders, and screens used at each property. The data obtained on feeders was confusing, but, rather than completely eliminate this information, it was decided to report it as given. The confusion lies only in the description of where the feeder is located. Where a primary feeder is listed it was not possible to determine if this feeder was on primary feed or primary discharge. For secondary feeders it is known that the feeder listed usually is feeding the secondary crushers, but at some properties it is handling the secondary crusher discharge. The same reasoning holds true for tertiary feeders-they handle either tertiary feed or discharge. This table contains a voluminous amount of data. A column giving tons per day per square foot of screen area would have been very informative, but some properties included circulating load in the feed rate and others listed new feed only, so calculations were meaningless. Autogenous Mills. The use of autogenous or semiautogenous mills for any property must be given serious consideration in the future. Table 3 lists data for four properties that are fully autogenous and four more semiautogenous mills that use balls to supplement the chunks of ore. This method of grinding is especially applicable when the ore is of such a nature that crushing problems would be severe, such as when ore is wet or sticky or contains a lot of fines. Paradoxically, it should also be considered when ore is tough and hard and blocky because then the competency of the ore means it can serve well as the grinding media. Where the ore varies greatly in hardness, as at Cyprus Pima and Lornex, semiautogenous grinding has been especially beneficial with capital costs and operating costs both 10-20% lower than could be obtained with conventional crushing and grinding. Rod Mills. For a great many years the standard milling operation used two- or three-stage crushing followed by open circuit rod mills and then ball mills in closed circuit with classifiers of some kind. A surprising number of properties crush to the fine size of about 3/8 in. and then use ball mills only, in closed circuit, with no rod mills. It is difficult to say whether rod mill-ball mill circuits or ball mill only is the best. One can be certain of two things: (1) the argument will go on for a long time and (2) for some mills one method obviously was superior over the other. As ball mills of 14, 15 ft, and larger came into use, more properties like Duval Sierrita (16b ft diam by 19 ft long) and Bougainville (18 x 21 ft) were built with single-stage ball mill grinding. Although there are larger rod mills used, especially in the iron ore industry, the largest rod mills on copper ore are at Twin Buttes (14 x 18.5 ft) and at Gibraltar (13'A x 20 ft). Table 4 lists operating data for rod mills. If a company is listed in Table I

Jan 1, 1985

By Dipl. -Ing. H. -J. Sager

The ‘Westerschelde Tunnel’ underpasses the estuary of the Schelde in the Netherlands. The tunnel will consist of two tubes which are driven by two hydroshields (slurry shields). The tunnels will each have a length of approx. 6.6km and a bore-diameter of 11.33 m. Demanding ground conditions had to be considered during the design of the shield machines. Loose sands, extensive clay formations and high ground water pressures of up to 6.5 bar will be encountered during the tunnel drive. The tunnelling activities will start in the middle of 1999 and are scheduled to end by the end of 2001.

Jan 1, 1999

By Doug Brown

The recent expansion of our cities into hilly areas, particularly on the Pacific Coast, has resulted in damage or destruction of many homes due to geological problems such as landslides, soil creep, erosion, subsidence, or groundwater seepage. In southern California, landslides are the principal cause of damage and attention is focused on them. Landslides have occurred due to the reactivation of old slide masses, or have been caused by grading and increased water, infiltration resulting from development.. Reactivation of a portion of the ancient Portuguese Bend landslide in Palos Verdes, Los Angeles County, affected approximately 150 homes. A common type of new failure' occurs when grading has undercut bedding or other essentially planar surfaces so that they dip unsupported out of slope. Other slides have occurred due to the inherent weakness of the material involved. Preventive measures undertaken to eliminate damage in the southern California area have. included areal geologic mapping programs-in-advance of development, enacting or strengthening grading codes, and requiring extensive studies by consulting geologists and soils engineers both during the design stage and during construction. In the design stage, proposed cuts are frequently flattened, lowered or reorientated. Frequently, due to the high cost of land, they are supported by compacted fill buttresses. As a result of these measures, the geologic environment has a major effect on the feasibility, design, and development of, a very substantial percentage of tracts or individual homes.

Jan 1, 1967

By Anthony W. Wakefield

The paper is intended merely as an introduction to methane hydrates, what they are and why they are important. It does not claim to be a cutting-edge research report, but may be useful for those to whom the subject is unfamiliar.

Jan 1, 2008

By C. W. Schultz

The Mineral Resources Institute at The University of Alabama is engaged in a program whose objective is to develop a beneficiation system for Eastern oil shales. Prior experience (1,2) at The University had shown that the grind required for liberation of the oil rich kerogen was substantially below 20~m. Based on this fact and the rapidly emerging consensus that column flotation is the preferred method for ultrafine particle separation, efforts were focused on the column flotation of oil shale. This paper, which must be regarded as a progress report on a continuing MRI project, describes the observations made and the results achieved to date. The investigation is being conducted in two phases. The first phase has been completed and consisted of a factorially designed experiment conducted for the purpose of screening a set of primary flotation variables. The second phase, which is still in progress, is focused on optimization of the operating conditions and development of a flowsheet for specific shales.

Jan 1, 1989

By G. G. Marino

Little comprehensive information has been reported on the behavior of room-and-pillar mines. The objective of this paper is to present case data on mine failures in the Illinois basin for use in practice. Presented are results of an ongoing study and details on the site characteristics of cases where sags have developed on the surface. Site data are reported to show the geologic, mining, and sag conditions that existed. Sags mainly develop from pillar, floor, or pillar-floor failure. The character of the sags depends upon the type of mine failure as well as the overburden response.

Jan 1, 1989

By H. H. Murray

New and improved benefication techniques are available to allow the production of clay minerals of exceptionally high purity. This is particularly true for kaolins and smectites. Wet processing techniques including particle size separation, high intensity magnetic separation, chemical leaching, flotation, and selective flocculation are described and results and applications are discussed. The blending of clay minerals with other minerals provide opportunites to make special ceramic materials such as cordierite and other minerals which have very special ceramic properties including low heat expansion, high fired strength, low absorption, and other desired qualities.

Jan 1, 1989

By B. Anameric, S. K. Kawatra

Pig iron nuggets were produced in a laboratory scale furnace at Michigan Technological University. These nuggets are produced from pellets consisting of a mixture of iron oxide, coal, flux, and a binder, which are heated to 1450°C.These pellets then self-reduce to produce a solid, high-density, highly metallized (96.5% Fe) pig iron. During the nugget production process, a separate slag phase forms that cleanly separates from the metal. The physical and chemical properties of the pig iron nuggets are similar to pig iron produced by blast furnaces, which is distinct from Direct Reduced Iron (DRI).

Jan 1, 2004

By M. Modis

According to previously established theoretical analysis and under certain conditions, a critical sampling grid can be determined for an earth-related space-distributed natural variable. Sampling above this critical limit adds little to the mapping results, while based on this limit the ideal process of reproducing the original phenomenon is theoretically defined. The objective of this paper is the application of the above theory to the Klidi lignite deposit in Florina, Greece, where Public Power Corporation (Greece) has conducted a sampling campaign to estimate the deposit thickness and its heating value. Data acquired for these two variables were analysed in the space domain in order to derive their respective correlation functions. The structural analysis of the deposit generated two covariance models, one for the thickness and one for the heating value, from which the critical sampling grid was identified. The conclusion drawn is that in some parts of the deposit the sampling grid is denser than required. Finally, an optimal sampling grid is proposed in order to gain the maximum information at the lowest cost.

Jan 1, 2006

By D. S. Choi

The paper contains a subsidence measurement taken over a room and pillar panel of a mine located in northern West Virginia. A total of 72 monuments were used to determine a three dimensional view of mine subsidence. In addition, the results of measurements were used to compute ground strains with the use of a numerical model.

Jan 1, 1982

By Robert W. Bruhn

The prediction of damage to a structure that is to be undermined is generally a two step process. First, the expected ground movements (the displacements, slopes, curvatures, and strains) are estimated using available (often empirical) predictive methods or survey data from a site of comparable geology, topography, and mining geometry. Second, the prospects for damage to the structure are assessed by comparing the expected ground movements to tolerable limits, some of which appear in the technical literature as damage criteria. The inverse problem of relating observed building damage to causative ground movements involves essentially the same elements. In either case, the usefulness of published damage criteria to subsidence problems may be limited in all but the most elementary cases. This paper considers several cases where structural behavior and site specific details had to be taken into account in assessing the relationship between damage and ground movements.

Jan 1, 1986

By K. L. Bickel

Catalyzed diesel particulate filters (CDPFs) are used for reducing diesel particulate matter (DPM) concentrations in underground mines. The U.S. Bureau of Mines is conducting research on how catalyzed diesel particulate filters perform. Two CDPFs, with two different catalysts, are used on vehicles in two mines. The CDPFs are periodically removed from service and evaluated in the laboratory to determine their DPM collection efficiency, regeneration temperature, and effects on gaseous hydrocarbon (HC) and carbon monoxide (CO) emissions. This report summarizes the results of the laboratory evaluation, and the mines' experience with the CDPFs. Both CDPFs have operated over 2,000 h. One was evaluated after 1,646 h; its collection efficiency at one operating condition was 87.3 pct. After 2,135 h of operation it was removed from service because it was damaged. The second CDPF continues to be used after 2,328 h of service. The laboratory evaluation indicated its collection efficiency decreased after 1,584 h of use and its regeneration temperature increased from 405' C to 420' C. The mines' experiences with the two CDPFs varied. While being used on mine vehicles, both CDPFs became plugged with DPM on a number of occasions because of insufficient regeneration. CDPFs are capable of lowering DPM concentrations in diesel exhaust. They can also lower emissions of CO and HC, depending on the type of catalyst used. In this study, the performance of the CDPFs changed with use. Recommendations are given in this report for proper use of CDPFs in mines.

Jan 1, 1994

By L. H. E. Weyher

A mine is essentially a vast materials-handling system. All other systems found in the mine exist to one degree or another to support the materials-handling functions, from the cutting at the face to the hoisting in the shaft. In this chapter computerized planning of underground materials-handling systems will be examined by dividing this function into: (1) the planning of the production section, and (2) the planning of underground rail or belt haulage from the production section to the shaft, slope, or surface. While alternative divisions might focus on the different materials- handling functions, i.e., production, supply, and manpower transportation, historical computer analysis has focused on the various systems rather than functions. The emphasis in this chapter is directed toward coal mine applications; however, most of the programs and methods are equally applicable to other underground mines. Markedly different methods are encountered in each system, and moreover, marked differences exist in the nature and the degree to which the materials-handling subsystems in each interact with the environmental or support systems. The most intimate interaction exists at the faces where geologic, human, and machine performance factors are closely related and constantly varying. In view of this, the planning of the materials-handling systems for the face will usually stress flexibility, while the outby materials-handling systems will generally place decreasing emphasis on flexibility and more on system reliability, capacity, and cost effectiveness. Thus, hoisting and main haulage systems are generally designed and constructed as permanent installations and cannot be readily changed, whereas secondary haulage systems and face operations are relatively mobile. These differences may have considerable significance for the mine planner in making technical and financial comparisons of alternatives to provide the scheduled mine production.

Jan 1, 1979

By J. R. Muhm

Environmental due diligence investigations, also known as Phase I Environmental Audits, are increasingly important to major investors, venture partners, or prospective purchasers or sellers of mineral properties. Knowledge of environmental risks associated with a property will allow better appraisal of a property's overall desirability prior to completing the transaction. It is possible that the cost of environmental cleanup could exceed the value of the property. Topics appropriately investigated include permit status, water quality, past use of the property, hazardous materials management, storage tanks, public records pertaining to the environmental character of the property, and environmental costs.

Jan 1, 1991

By S. Crewdson

Vertical hoisting of materials using hoists and skips is common in the Mining Industry. These systems have a number of drawbacks, one being limited hoisting capacity at medium depths. FKC-Lake Shore and Metso Flexowell have been developing and installing vertical belts for medium depth shaft applications for many years, progressively going deeper whilst increasing belt capacity. The latest development from Metso the Pocketlift® belt advances this technology allowing higher tonnages to be lifted from greater depths. The design, manufacture, installation and operational experience of a 1818 tonnes capacity, 273 meters vertical lift Pocketlift® system at the White County Coal Pattiki 2 mine is the subject of this work.

Jan 1, 2003

By David C. Slack

In recent years public concern over the environment has grown enormously. A very aware populace has exerted pressure on its legislators to enact enforcement laws dealing with pollution. Among the different types of pollution, sulfur dioxide in the air is a large and readily identifiable constituent. Air pollution, according to the EPA, costs the U, S. billions annually with SO2 a major portion of this cost. Fossil fuel and oil fired power plants release better than 50% of the SO2 in the country. Thus great attention is being focused on the methods power plants are utilizing to control emissions. With a time schedule of compliance by early 1975, decisions are being made and systems chosen that will have to perform - and perform - and perform. Therefore, a large majority of the power plants are presently considering lime in the planning and operational phases of their stack gas desulfurization programs. The reasons for this are: Lime scrubbing has more development and pilot work completed than most other methods; the removal potentials are relatively high; the stoichiometric ratios are not excessive and, the process has relatively low capital and operating costs. Many pilot plant studies have been completed recently using lime and the first operational full scale lime scrubbing unit is now in the start-up phase at this time at Duquesne Light Company's Phillips Station here in Pittsburgh. Also, because of completed development work, the problem of solid waste disposal will also be tackled at this power station at the same time. There are various methods for the use of lime in scrubbing for S02, but for our purposes I would like to describe the cyclic wet lime process. This method called "Scrubber Addition of Lime" involves contacting the flue gas with a slurry of milk of lime.

Jan 1, 1973

By Mike O’Brien, Rob Croll

The Evolution of AngloGold -Incorporated in 1944 under the name of Vaal Reefs Exploration and Mining Company Limited -Name changed to AngloGold Limited in 1998 as the vehicle consolidating the gold interests of Anglo American Corporation -Diversification (geographic and orebody) through the sale of low-margin, deep level, short-life assets and the acquisition of higher margin, open-pit and shallow underground operations

Jan 1, 2003

By Dennis Keay, Barbara Schickner, P. L. Longenecker, Glenn J. Philips, Lee Rice, Herman E. Knight, Wayne E. Veneman, B. W. Washington, Robert S. Hess

The outlook for coal continued to improve in 1980, fueling expectations that a long-awaited boom is at hand. The surprising surge in coal exports contributed to the latest wave of optimism. Overseas exports hit 66 Mt in 1980, buoyed by a significant increase in demand for steam coal, up from 1979's 2.3 Mt to 15 Mt in 1980. US coal production rose 6.9% to 750 Mt in 1980 and total coal consumption increased 8.1% to about 725 Mt, due primarily to higher world oil prices and setbacks in the US nuclear power industry. Yet the industry is beset with problems-both internal and external. Although demand for US coal is growing, the industry's excess productive capacity is estimated at over 90 Mt/a. Public utilities, where real increases in coal consumption must come, are still moving slowly, blaming delays on antipollution equipment costs. Coal supplies are uncertain, subject to the vagaries of the UMW. For the sixth time since 1964, the coal industry and UMW failed to renew their labor contract without a national strike, reinforcing the perception held overseas that the US is not a reliable supplier. The expected boom in coal exports will, in part, depend on our ability to assure foreign buyers that US sources are dependable. The US industry is also plagued by inadequate facilities linking mines and consumers: inadequate rail systems, coal ports, and barges, For US producers to be competitive, ports must be expanded, rail lines improved, and harbors dredged to allow 136-kt ships to load coal. The im¬provements will require an enormous commitment and investment. Despite these major problems and unresolved issues, two factors continue to favor an increased reliance on coal as an energy source: abundant US reserves and coal's comparative price advantage. Coal's performance in the 1980s may at last exceed its promise.

Jan 5, 1981

By C. McDonald, S. Slottee

Deep "paste" thickeners have been used in the alumina industry for several decades to improve chemical recovery and allow “stacking” of the red mud for disposal. These paste systems have eliminated many traditional tailings ponds in addition to providing better tails washing and better water recovery. This technology is not widely used or understood in other mineral processing applications. However, there is growing worldwide recognition of the advantages of concentrating mill tailings to a “paste”, i.e. a solid suspension that does not settle or segregate. This technology offers several alternatives to the traditional tailings pond such as “stacking” or mine backfill. More water recovery is possible than with high rate thickeners. Process benefits come in the form of better chemical and metals recovery through better washing in counter current decantation (CCD) applications. Obtaining a true paste (non-segregating suspension which exhibits a yield stress) and understanding the handling characteristics for applications outside alumina, are recent developments. Achieving all of the benefits available from a paste system requires careful design that takes into account the specific requirements of the disposal application along with the peculiar difficulties in producing and handling paste. In fact, design of a paste system is markedly different from a conventional system. Project design usually requires the cooperation of experts in several interrelated specialties including geotechnical, thickener design, pumping and discharge design and controls. A successful project must coordinate all activities to ensure that the overall objectives for the project are achieved. This paper describes the properties of paste, reviews the applications, and discusses the design of a complete paste deposition system.

Jan 1, 2003

By P. B. Altringer

The Bureau of Mines, U.S. Department of the Interior, is investigating biodegradation of cyanide as a means of decommissioning heap leach operations. Biological oxidation decreased weak acid dissociable (WAD) cyanide in process solutions1from 50 to 170 ppm down to 0.1 ppm. The tests were conducted both in trickling column reactors, using quartz as the growth surface, and in upflow columns, using activated carbon as the growth surface. In addition, exploratory tests indicated that bacteria will destroy residual cyanide in leached ore. A flowsheet has been proposed for closure of heap leach operations in which the metals processing portion of the plant, possibly the carbon adsorption columns, or a collection pond is used as a bioreactor. The cyanide in the process solution is destroyed in the bioreactor and the treated water is used to rinse residual cyanide from the spent heaps. The water is recycled until the effluent WAD cyanide concentration meets discharge standards.

Jan 1, 1992