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By K. L. Browne

After a decade of high copper prices, major mining companies are renewing their interest in purchasing operating properties and/or developing ore bodies. An existing operation carries with it a history that can present unique opportunities, while a greenfield operation allows for the establishment of a defined culture. Capital investments are distinctly different. A comparison of BHP Copper's Robinson operation, a greenfield property, and BHP Copper's Tintaya operation, a government owned Peruvian property, will provide insights into mining, concentrating and cultural differences between North and South America operations. The Broken Hill Proprietary Co. Ltd. (BHP) is Australia's second-largest company. Fiscal year 1996 sales were US$16 billion, profits were more than US$1 billion and total market capitalization was about US25 billion. In 1885, BHP began mining silver, lead and zinc at Broken Hill, New South Wales, Australia. Throughout its 112-year history, BHP achieved an impressive record of performance and expansion. Today, BHP is one of the world's leading companies (66th on the Standard and Poors 500), having diversified into steel, petroleum and mining with more than 65,000 employees in 70 countries.

Jan 1, 1997

By Hubert E. Sherer

The mining industry is presently one of the most heavily capitalized industries in the U.S. (U.S. - Statistical Abstracts, 1979). U.S. sales of new mining equipment (not including environmental, preparation, or long distance transportation equipment) are projected to reach approximately $5 billion/year in 1980 (Frost and Sullivan, 1979). Of these new equipment sales approximately 30 to 40 percent of this equipment will be used to replace old equipment. Therefore, an increase of efficiency in the use of equipment replacement capital could have substantially positive effects for the U.S. mining industry. This is very critical in these times of restricted capital availability, double digit inflation, burdensome governmental regulation, and rising foreign competition in the mining industry. This paper examines the numerous factors that constitute the typical mine equipment replacement problem. A computerized, mathematical model is formulated to utilize historic cost and production information to predict equipment cost versus age for the existing and potential replacement machines. Another part of this computerized model determines the best equipment replacement strategy that accomplishes estimated production goals at a minimum discounted cost. This computerized model is an easily used, consistent method of determining the optimum replacement age for any equipment unit or fleet of equipment at a mining operation.

Jan 1, 1982

By J. Richard Kyle

Salt domes, their cap rocks, and the adjacent sedimentary strata represent a major economic resource in the Gulf of Mexico basin. Gulf Coast salt diapirs formed in response to sediment loading of the "mother" Louann evaporite sequence of middle Jurassic age, an effect that is caused by the buoyant nature of the lower density salt. Halokinesis progresses from nonpenetrative deformation that creates broad "pillow" structures into discrete high-amplitude diapirs. Because of its buoyancy, the top of the salt diapir remains near the land surface or the seafloor during much of its history as the basin floor subsides. The salt within the Gulf Coast diapirs is deformed complexly and commonly shows subvertical banding that represents modified sedimentary layers with different contents of nonhalite components. The most abundant impurity is anhydrite, which occurs as individual millimeter-scale crystals or as deformed clasts that generally form about 5% of most salt stocks. Many mature salt diapirs are mantled by a "cap rock" that consists of a lower anhydrite zone and an upper calcite zone, commonly separated by a discontinuous gypsum-bearing zone. The anhydrite zone forms as accreted layers of anhydrite grains and clasts that are left after episodes of halite dissolution. The calcite zone is a product related to petroleum destruction accompanying bacterial reduction of aqueous sulfate. Calcite-cemented siliciclastic strata occur above or alongside diapirs. The mineral resources of the salt-dome setting are remarkably diverse. Major economic products of the salt-dome environment are salt and cap-rock-hosted native-sulfur deposits, as well as petroleum resources that occur on the dome flanks and in the cap rock. Native sulfur forms as a result of bacterial sulfate reduction accompanying petroleum destruction to form hydrogen sulfide, which is subsequently oxidized to elemental sulfur, major amounts of which have been produced by the Frasch process from Gulf Coast salt-dome cap rocks. Some cap rocks have produced limestone, gypsum, and anhydrite for a variety of construction uses. Although traditional industrial-mineral resource production from Gulf Coast salt domes is shrinking, some cap rocks host potentially commercial concentrations of celestite and barite, as well as the metals Zn, Pb, and Ag. Furthermore, caverns, excavated within the salt stocks, serve as major storage facilities for crude oil (including the Strategic Petroleum Reserve), liquefied petroleum gas, and natural gas. These resources are products of fundamental geologic processes that are integral to the evolution of the Gulf of Mexico basin. Whereas production of some industrial-mineral resources, such as elemental sulfur, has declined in recent years, ample reserves of salt will allow production to continue into the foreseeable future. Further, there is potential for other mineral-resource production from cap rocks under favorable economic circumstances. Expanded use of caverns, excavated in the salt masses for material storage and disposal, is likely to continue into the next century.

Jan 1, 1999

For all the attention given to mining activities in Central and South America, Mexico, Indonesia and Papua New Guinea, it is sometimes easy to forget the activities taking place in one of North America's most important and largely untapped regions -Alaska. The Alaskan minerals industry employed about 3,406 people during 1995. That is a 23% increase from - - 1994. It also contributed about $719.8 million to the state's economy during 1995, a 10% increase. During the past few years, Alaska has seen significant increases in exploration and mining activity. Fairbanks Mining, an arm of Cyprus Amax, began producing gold during 1996 at its Fort Knox Mine, as did Nevada Goldfields' Nixon Fork gold mine. Kennecott's Greens Creek lead-silver-gold mine also reopened and USMX began operations at its Illinois Creek gold mine. In addition, several impressive exploration projects were under way in Alaska. Placer Dome reported good results at Donlin Creek project in southwest Alaska. Likewise, Newmont Exploration is getting serious about its True North gold project. And Nerox is nearing production at its Jonesville coal project in Alaska's interior. In November, about 400 miners gathered in Anchor- age for the Alaska Miners Convention. Throughout the conference and exhibition, attendees listened to updates on these precious- and base-metal and coal exploration and mining operations. They also learned that the state wants more miners to head north and help develop its natural resources. Alaska is ripe for a smelter The mining industry -Alaska's miners in particular - has a powerful ally in Sen. Frank Murkowski (R-AK). He is the chairman of the Senate Energy and Natural Resources Committee. During his luncheon address, Murkowski said it appears that it is economically feasible to extend the Alaska Railroad to northwest Alaska, taking advantage of the large coal and hard-rock mineral tracts in the Ambler mining district. He also renewed his push for building a major smelter in Alaska to process ore that would come from the Ambler mining district. Murkowski believes that Alaska's economy can be expanded by extending the railroad from Nenana to the Point Lay coal fields to open coal development. Along the way, the railroad would pass through the Ambler district, helping to develop the hard-rock deposits. An outgrowth of this additional mineral development, Murkowski said, could be a new smelter in Alaska. It could use power from the Tyee hydroelectric facility near Wrangell or from the Makushin geothermal project near Unalaska. Either site, he added, offers access to plentiful, relatively low-cost power, at tidewater to facilitate ore deliveries to the Pacific Rim. The Congressional Research Service has determined that there are enough mineral deposits and coal beds to make it possible to finance the extended railroad, he said. The 1,200-km (744- mile) rail extension would cost about $4.2 billion. The North Slope of Alaska contains up to 3.6 Tt (4 trillion st) of coal, Murkowski said, that contains less than 0.25% of sulfur and less than 4% moisture. It aver- ages 12,300 Btu in heat content. "That is a tremendous resource," he said. The Ambler mining district, meanwhile, has at least eight identifiable hard-rock deposits, Murkowski continued. These contain zinc, lead, copper, nickel, chromium, tin, barite, gold and silver. "All eight of these can generate ore concentrates at rates similar to Red Dog's cur- rent 725 ktla (800,000 stpy)" of zinc, he said.

Jan 1, 1997

By William H. Mount

INTRODUCTION The requirements of mine ventilation demand the constant attention of the mine operator. Just as the physical mine structure changes with time, the ventilation requirements of a particular mine change considerably from season to season and even from day to day. No ventilation system can remain adequate indefinitely; and all systems require monitoring and adjustments to achieve proper ventilation. Instead of being given fore- thought and planning, mine-ventilation systems too of- ten are erected hastily, merely to correct an already un- healthy situation. The usual result is an inefficient and costly system that, in some instances, may prove in- effective in providing fresh air to the point of need. The ventilation of mines is a combination of both art and science. The fluid that must be moved is in- visible; its properties change drastically with temperature, barometric pressure, and humidity; and the methods of measurement are not precise. In part, ventilation engineering must rely upon the art of good industrial ventilation experience and sometimes even the trial-and- error method. However, the properties of air can be determined with relatively inexpensive equipment; with some care, measurement accuracies within 5% of the actual values can be obtained. Thus the art of ventilation gradually is being supplanted by improved engineering practices. Although the direction of flow and the volume may not be predicted correctly by airflow equations in every situation, it is better to try to predict the behavior of a given ventilation before installation than to proceed blindly with a system design. When used with the discretion that comes from education and experience, the basic laws of ventilation can provide sub-stantial insight into the design of an air-handling system; and they can prevent wasteful or even dangerous designs from being installed. Since the mine operators who read this text will have varying amounts of exposure to ventilation theory, the basic laws of airflow and of mechanical ventilation are presented in the first section. The emphasis has been placed on the interpretation and use of fan characteristic curves that are supplied by fan manufacturers. Considerable information can be obtained from these fan curves, particularly when they are used with a graphic model of the mine, drift, or duct in which the fan or fans are to be installed. A few minutes spent comparing the various characteristic curves can help the designer obtain the correct fan for the job. However, the under- standing of a few fundamentals is necessary; and this text has been prepared to provide ample and understandable information in a "how-to" style. In subsequent sections of this text, more down-to- earth subjects will be covered, including the problems of air recirculation, relative merits of installing fans in series or in parallel, expected maintenance requirements (vibration, lubrication intervals, etc.), fan noise and some remedies, effect of an inlet bell on the fan per- formance, basic air-measurement techniques and equipment, and similar miscellaneous items. Although this text is not intended to be a comprehensive bible of mine ventilation, it has been prepared as a guide that provides some useful information to individuals responsible for the quality of the underground environment. Every person working underground is en- titled to the safest environment that can be provided within the limitations of existing technology and at a reasonable cost. Adequate ventilation is well within both limits, provided that the system is designed intelligently, in conjunction with the mining plan, and not as an after-

Jan 1, 1982

By J. J. Fallon

Las Vegas is a place of many distractions. It is difficult for one to apply himself to sophisticated technical matters in the midst of gambling, liquor, scantily clad young ladies and the top entertainment available in the United States. But, I know that the men and women of SME are made of stronger stuff and will not be tempted by these things.

Jan 1, 1989

By S. Jennings

The Red Dog massive sulfide deposit is located in the western Brooks Range of Alaska 100 miles north of the village of Kotzebue. It contains the largest zinc reserve in the world. Reserves were doubled in 1995 with the discovery of the Aqqaluk deposit and significantly increased in 1996, with the discovery of a deep zone of mineralization to the north. At present the global reserve and resource is 143 million tonnes of 16.1 % zinc and 4.3% lead. Red Dog is a silica + sulfide synsedimentary replacement deposit hosted in barite and black shale of the Mississippian Kuna Formation. Red Dog was thrust northward during the late Mesozoic Brookian orogeny. Understanding the setting of the deposit at the time of formation and its subsequent deformation history is critical to current exploration efforts and to future discoveries in the district.

Jan 1, 1998

By R. D. Lord

This paper deals with the search for the best practical means of storing sulphide bearing tailings, where there is no residual excess of carbonate material. It is the common experience that the sulphide content decomposes, with the aid of bacterial action, and the resulting sulphuric acid escapes, along with any heavy metal solutes, through embankments that are usually porous to some degree. The problem is typified in the tailings of the uranium operations of Elliot Lake, Ontario, where mining started some 20 years ago. The approach to tailings disposal paralleled the practice for other hydrometallurgical plants treating gold and base metal ores. Impoundment areas were designed to retain solids, and a clear and neutral overflow was considered satisfactory practice. Now experience has shown that these areas, some idle for over a dozen years, release acids, in seepage and overflows, to an unacceptable degree. To protect natural water courses neutralizing plants are operated wherever required. Lime slurry is fed continuously into the tailings outflows in a quantity sufficient to raise the pH to 8.5 and precipitate heavy metals that may be in solution. The objection to this procedure is that the plants will require servicing indefinitely, unless a better remedy is found.

Jan 1, 1975

By William Kohan

The industrial grinding process has undergone changes to better address the market and economic needs. Fine grinding of dry materials has developed to the point where classifying linings and fine ball charges improve mill efficiencies. Roller mills as well have wide acceptance due to their power efficiencies. The mill, by its nature, cannot provide the specific particle size or range of sizes which are required for further processing or final use. Therefore, various separators are operated in conjunction with the mill to control particle size. The sizing device helps minimize over grinding and control top size. Rising energy costs combined with increasingly tighter quality specifications have led to increasing study of the grinding and separation process.

Jan 1, 1985

By M. J. Senk, A. Lusin

Federal regulations require that methane liberated at the face be diluted and removed to maintain methane gas concentrations below 1pct (CFR) in working places and intake air courses. The delivery and distribution of intake air at the face is critical for effective face ventilation. Improved techniques for monitoring the movement of intake air to the face are needed. A test system was developed and a computer program written for using a three-axis ultrasonic anemometer to measure airflow in a simulated mine entry. Results of tests conducted in the entry showed that the anemometer is a valuable tool for measuring mine airflow conditions near the face.

Jan 1, 2003

By Douglas J. Uhren, Gary W. Gilbert

This paper describes the risk elements associated with difficult glacial geology, including boulders, heavy groundwater inflow, and potential running soils all coupled with a potentially corrosive service environment. The matrix workshop for the 168-inchfinished diameter sanitary sewer interceptor tunnel in Columbus, Ohio is assembled with the Design Team and the Owner’s design, operations, and fiscal staff. Corrosion protection alternatives are compared against cost and non-cost parameters with relative risk and weighting factors assigned. The Owner working in cooperation with the Design Team uses the matrix workshop to se

Jan 1, 2001

By V. M. Torres

Arapiraca ore deposit has a mixed chalcopyritelbornite mineralogy, with a copper head grade of 0.7%. The reserve size does no allow profitable exploration by grinding/flotation. The technical feasibility of exploring the reserve by heap leaching was studied. Preliminary agitation tests indicated 85% copper recovery. To simulate heap leaching, column tests were performed. The tests included different ore types and acid addition levels. Operating at pH range 1.6-1.8, 67% copper extraction was achieved. Also, it was found an empirical correlation between the operation pH range, copper extraction and acid consumption.

Jan 1, 1996

By J. Engesser

This paper discusses the effect that water chemistry, and water treatment have on pre-fired pellet quality and bentonite-binding effectiveness. A discussion concerning the effect that water temperature, water chemistry, water treatment, and surface area have on disc filter productivity and filter cake moisture is also included. This report is a summary of the data that were presented in five previous research reports, which are listed as references in this paper.

Jan 1, 2003

By P. L. Dunn

Automatic control of fine coal cleaning circuits has traditionally been limited by a lack of sensors. Although several nuclear-based analyzers are available, none have seen widespread acceptance. In this investigation, image analysis is used for on-line determination of ash content in fine coal slurries. The ash content of a flotation tailings stream is correlated to the mean gray level of the slurry. Based on a 90% prediction interval, an analysis of sensor performance indicates an accuracy of 73 ± 4% ash over a range from 65-90% ash. While this result is comparable to existing nuclear-based analyzers, the video-based system is only a fraction of the cost. The sensor is currently installed at the Middle Fork preparation plant owned by Pittston Coal Company.

Jan 1, 1997

By Don Reining

The sand and gravel industry in Southern California has made a sizeable contribution to the construction development of the 15 County area in this part of the State. Facing this mineral extraction industry, in the next decade, is a problem of meeting the market demand. The question is, "how can sand, gravel and rock operations be made compatible with goals for sound and attractive community development?" Three basic principal characteristics of the land needed for this-mining industry are: 1. The land must have workable sand, gravel or stone deposits. 2. The land must be properly located for transportation purposes close to the market in order to sell the aggregate at a minimum cost. 3. The land must be zoned so that it will be permissible to mine.

Jan 1, 1967

In 1991, most industrialized countries, except for Germany, were in a recession or a period of reduced growth. The US economy, already in recession, suffered from mounting banking system losses and the uncertainty brought about by the Persian Gulf War. However, US and worldwide minerals exploration did not collapse as it did during the mid-1980s. Even though gold and base metal prices declined, prices were still above cash costs for most operations. This allowed the continuation of established exploration programs but sharply limited new initiatives. Exploration 1990-1991 Planned worldwide 1991 exploration expenditures declined by about 8% from 1990 levels, according to a survey of 153 companies by the Metals Economic Group (MEG). Canada was the leading exploration target with 23% of the total, followed by Australia and the US (19% each), South Africa (13%), Latin America (11%) and the South Pacific (7%). The remaining 8% was split evenly between Europe and the rest of Africa. In Latin America, Mexico and Chile are the most attractive countries for exploration. Recognizing the risks involved, the industry has been cautious about ventures in the former Soviet Union. Survey results also showed that while the majors expected to maintain exploration spending, smaller firms were cutting back or actively seeking farm-outs from the majors (personal communication, M. Wegener, MEG).

Jan 1, 1992

MULSIM/NL and La Model are displacement-discontinuity programs which have been used quite successfully in the past to provide detailed structural models of various single and multiple-seam mining situations. However, both of these programs required fairly complex details of the mine plan and topography to be manually input into the program, often taking several days of work. Recently, automatic mine and topographic grid generation capabilities have been added to the MULSIM/NL and La Model programs, reducing the input time requirements from days to hours. This paper discusses the algorithms used for the automatic grid generation and demonstrates the utility of the new capabilities with a case study.

Jan 1, 2003

By Kenneth S. Johnson

Oklahoma is a region of complex geology where a mobile belt of Paleozoic geosynclines and uplifts on the south abuts against the margin of the North American craton to the north. The state contains many classic areas where fundamental concepts of sedimentation, stratigraphy, structural geology, historical geology, mineral investigation, and petroleum exploration have been formulated through the years. In the southern Oklahoma mountain belts, there are exposed a great variety of igneous and sedimentary rock units seen at few other places in the Midcontinent area. Major geologic provinces of Oklahoma (Fig. 1) include: (1) the cratonic and relatively stable northern shelf areas, including the Ozark uplift; (2) the Ouachita geosyncline (now the Ouachita Mountain belt) and associated Arkoma basin in the southeast; and (3) the southern Oklahoma aulacogen (geosyncline), comprising the area of Anadarko, Ardmore, Marietta, and Hollis basins, as well as the Arbuckle and Wichita Mountain uplifts. The three principal fold belts, the Ouachitas, Arbuckles, and Wichitas, all originated from a series of Pennsylvanian orogenies (about 300 million years ago) in the two Paleozoic geosynclines.

Jan 1, 1999

By Murray Malott

The Sheppard Subway extension is currently being constructed in Toronto, Canada for the Toronto Transit Commission (TTC). McNally International Inc., in a joint venture with PCL and the Foundation Company of Canada were awarded the Twin Tunnels contract of the Sheppard extension. The Twin Tunnels project is approximately 4.4 km in length and consists of two separate twin bore drives each 3.3 km and 650 m in length and approximately 400 m of cut and cover construction. This paper presents a case history of the construction of the soft ground tunnels through the complex Toronto glacial deposits using two 5.9 m outside diameter Lovat earth pressure balance (EPB) tunnel boring machines.

Jan 1, 1999

By K. L. Johnson

Networks of monitoring wells were established prior to mining at four longwall mine sites in the Appalachians to monitor the effect of mining on water levels, water quality and well yield. Two of the sites were located in stream valleys and the other two sites were located on hilltops. The depth to the mined seam ranged from 500-850 feet with the deeper cover being associated with the hilltop sites. Maximum declines in groundwater levels during and after mining were an order of magnitude less in the stream valley aquifers than in the hilltop aquifers. However, water levels in hilltop wells located outside the area immediately above the panel were unaffected. Water quality changes in wells as a result of longwall mining were negligible at all four sites. Increases in aquifer transmissivity and well yield were much more pronounced in the stream valley aquifers than in the hilltop aquifers. The significantly larger recharge area for the stream valley aquifers than that for the hilltop aquifers may partially account for the differing responses of these two classes of aquifers to longwall mining. These observations appear to be consistent with the stress-relief fracture model for Appalachian Plateau groundwater hydrology proposed by Wyrick and Borchers in 1981.

Jan 1, 1986