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By S. Lin, Y. J. Wang

Through an example three fan ventilation network concepts of subsystem solution and characteristic curves of a multiple fan ventilation system are introduced. The major steps of defining a subsystem, working out the subsystem equations, constructing a solution curve and a characteristic curve, and determining the operating points of the reference fan and the ventilation system are systematically demonstrated through three and two-dimensional curves. Also briefly discussed are the main features of a subsystem characteristic curve.

Jan 1, 1993

By X. P. Zheng, H. K. Lin

During slow-cooling crystallization of iron-making blast furnace slags, most rare earth elements recrystallize in an artificial "mineral" identified as calcium cerite. Scandium (Sc) and europium (Eu), however, concentrate in a sheetlike "mineral." In this investigation, the mineralogy of this sheetlike "mineral" was studied. It was identified as being in the mica group and was called a rare earth-bearing barium fluorophlogopite. One of the objectives of this study was the recovery of this "mineral." The study indicated that it can be effectively recovered from the slag by flotation using dodecylammonium acetate or a combination of dodecyl-ammonium acetate and sodium oleate as collectors.

Jan 1, 1998

By A. C. T. Bigg, A. F. Colombo, A. R. MacPherson

The step-by-step study of the Stronsay ores follows the testwork through the initial determination of Bond Rod and Ball mill work indices, the MacPherson Autogenous work indices and the production of a preliminary flowsheet. These results are then used to design a pilot plant program to test the effectiveness of fully autogenous primary and secondary grinding and to determine the feasibility of controlling feed rate by the use of variable speed mill drive and/or varying the mill load. A final flowsheet is recommended with mill sizes and power requirements.

Jan 1, 1992

By Roshan B. Bhappu, Sukhendu L. Barua

The economics of developing and operating small precious metal mines are unique and require much more scrutiny than larger mines since a limited tonnage must carry a heavy burden of capital investment as well as operating cost per unit ton to be mined and processed. Moreover, potential operators of small mines do not have the required expertise available to critically evaluate the technical and economic aspects of their projects. In this paper, the authors have attempted to provide technical and economic guidelines for developing and operating small precious metal mines. Capital and operating cost estimates as well as return on investment are provided for various scenarios utilizing different mining and processing techniques.

Jan 1, 1987

By Carlos E. Avila, Ronald D. Evans

The results of an experimental research program to measure the non- Darcy flow coefficient as a function of temperature and overburden pressure are presented. The experimental values of the non-Darcy flow coefficient were measured over a temperature range of 70-200°F (21°-93"C)and overburden pressures of 1000-4000 psia (68-272 atm). The data obtained confirm that the non-Darcy flow coefficient is a function of rock and fluid properties and is not solely dependent upon the former has been routinely assumed in the literature.

Jan 1, 1986

By Chris Chmura, Ketut Karmawan, Ian J. Duckworth

P.T. Freeport Indonesia operates a mining complex located in the highlands of West Papua, Indonesia. Present production from PTFI’s DOZ Underground Block Cave Mine is approximately 40 thousand tonnes per day (ktpd). This paper describes the design process and recommended ventilation infrastructure necessary to expand the DOZ Mine reserves and to increase sustained daily production above 50 ktpd. The enlarged footprint will feature longer production panels of up to 650 m in length, more active draw points, a second large gyratory crusher, and additional men and mobile equipment. The increased ventilation capacity will be achieved through the development of new, dedicated ventilation drifts, and primary Underground exhaust fans.

Jan 1, 2005

By Tim Wolf, Barry Fink

Mine site managers reported occurrences of locking assembly bolt failures on the Enlow Fork Coal Mine's slope belt conveyor. The observations were made after a number of years of operation and raised questions as to the status of the assemblies in operation. These questions prompted a detailed review of the situation by independent consultants. Using operational history of the conveyor and confirmation of belt loads by static and dynamic methods, a locking assembly fatigue curve was created to suggest expected service life. From this work, suggestions were made to modify the pulley assemblies for extended service life.

Jan 1, 2002

By Malcolm J. McPherson

This paper describes the algorithm used in a BASIC program for an IBMXT microcomputer, to simulate the underground mine climate. The program called CLIMSIM has been developed and refined over several years as a result of considerable use at operating mines. The program has been designed to be easy to use and be understood by the practicing mine ventilation engineer. It provides predictions of the work place climate, so that the optimum ventilation/cooling system can be designed to obtain a certain air cooling power or effective temperature at the work place. An example is given of the application of the program to a mechanized cut and fill stope at the Homestake gold mine in South Dakota.

Jan 1, 1986

By J. H. Bassarear, J. D. Vincent

General. Copper, the first metal used by man, today is the third in consumption after iron and aluminum. Compared to these it is relatively rare, with less than 0.01% of the earth's crust copper, 8% aluminum, and 5% iron. Nevertheless. our modern civilization is heavily dependent upon copper because of its high conductivity and resistance to corrosion, ease of working, durability, wide range of properties by virtue of its readiness to form alloys with other metals, and its attractive colors and texture that make it so desirable for many crafts and arts. These attributes explain why copper is chosen for a long list of uses, including electrical wiring, switchgear, and bus bars; piping, roofing, and siding; and manufactures of brass, bronze, and other alloys. The fact that copper ore is mined in nearly all parts of the world is significant. Its importance is shown in Table I, which gives figures on world production from 1968 to 1977. In the Free World, North and South America and Africa are preeminent. The table also shows the generally upward trend of production in this period; accurate figures for 1978 and 1979 from the same source are not yet available (1980), but it is certain that major environmental, economical, and political factors continued to disturb the industry in those years and into 1980.

Jan 1, 1985

By William S. Eaton

Managing a mine or mineral processing operation in today's environment presents many unique challenges to mining companies. In recent years, headlines around the world have publicized major incidents such as those associated with the Marcopper Mine in the Philippines, the cyanide release in Guyana from the Omai gold mine and numerous other mishaps associated with mining. These notable upsets were due to engineered system failures, either during normal operations or as a result of uncontrollable events. There fore, many mining firms are attempting to assess their overall risks and establish some priority for expenditure of limited operational and environmental budgets. Failure of an engineered component can have dire operational consequences that affect profitability until repair or replacement can be completed. In addition, there may be significant environmental consequences associated with the engineered system failure. This, too, may affect profitability for an extended time or even the viability of an operation. An engineered risk assessment (ERA) can support a mining company's efforts to cost effectively manage environmental risks associated with the operation of its facilities. The ERA approach also provides information about the current condition of engineered systems. This ERA approach provides a systematic review of the risks of an engineered system failure and the possible associated environmental consequences at mining company facilities. This approach has been successfully applied to many industries and types of engineered systems (Barneich et al, 1996; Whitman, 1984; Power and Tomkins, 1974; Keeney, Nair, and Kulkarni, 1979). This approach evaluates all mining and mineral processing facilities located at a single site and compares them with similar facilities located at multiple mine sites. The ERA approach has been applied to a mining, milling, smelting, leaching and refining operations. These assessments can be part of a comprehensive environmental program to aid in the recognition and cost effective management of the potential environmental risks associated with the operation of facilities. ERA results support plan-

Jan 1, 1997

By E. D. Attanasi

The US mining industry finished the traumatic 1980s with a strong economic performance. Worldwide economic growth and capital spending led to tight metal markets. So, 1989 metals prices were generally higher than average 1988 prices. Financial markets' volatility resulted from US junk bond defaults, heavy US savings and loan losses and effects on the US budget deficit, higher energy prices, and the seemingly intractable problems of some debtor countries. Moreover, the events in Eastern Europe promise fundamental changes in the world economic system for the 1990s. US mining companies that survived the decade had weathered economic changes that, at one point, reduced industry employment by 40%, drove oil companies to divest or liquidate recently acquired mineral subsidiaries, and led to substantial write-offs of reserves. Canadian and other international minerals firms experienced similar industry upheavels. The forced modernization and capacity rationalization produced an internationally competitive US industry. For example, even though 1989 US copper production was 27% greater than in 1980, industry employment was less than half the 1980 level. The steel industry and other minerals industries showed similar productivity improvements.

Jan 1, 1990

By Patzen Wu

The Hai-Shan No. 1 Coal Mine, located in northern Taiwan, is one of the typical coal mines on the island which, limited by natural condition, are mostly small in scale. With the advancing longwall method, the mine is now winning a seam, 80 cm thick, at a 32° dip, with a working depth of 824 m below surface. The annual output is about 50,000 mt of clean coal. At the working gallery, the virgin rock temperature may go up to 46°C, difficult to be brought dam to n acceptable level: because .of the tropical climate with high intake temperature and high humidity. Besides, at this depth, the intake air that goes down the long inclined shaft generates considerable heat due to autocompression. The mine is ventilated by a set of axial-flow fan with 38 m3/S of intake air at 2.2 KPA WG. With this volume of air, the temperature at the working-face is usually above 30°C WB. Appreciable lowering of the temperature is not expected even with an increased volume of ventilated air. For this reason, decision has. been made to try the installation of a pilot underground refrigeration unit near. the lowest gate road to cool the intake. air. from 32°C WB to 28°C WB which seems acceptable to on-the-spot workers exerting heavy physical labor. The experimental unit is designed for carrying away a total heat load of 90 Kw. The capacity of the unit is 200 Kw. The unit consists of a compressor, an evaporator, a condensor and a motor. The heat rejection is done in a cooling tower. Chilled water is circulated from the evaporator to the cooler by insulated pipes. The cooler consists of 90 Kw-coils with two fans and forces air by flexible ducting onto the working face. This paper examines mainly the effect of this additional reduction of working temperature, on working efficiency of the workers. Another aspect of this experiment is to evaluate the overall economy of underground refrigeration in small-sized coal mines under tropical condition. The success of such an experiment may lead to wider application of refrigeration to render many of the deeper mines economically workable.

Jan 1, 1980

By W. J. Schlitt

Introduction A major uncertainty in assessing the potential for heap-and dump-leach projects is how to determine the extraction-rate curve for the recovery of the mineral values from coarse ore. Such material could either be run-of-mine (ROM) or primary crushed ore. The problem with field testing coarse ore, especially for new projects, is the large scale and extended leach times needed to accurately determine the final extraction-rate curve. At least 5 x 103 to 5 x 104 t of representative ROM ore are typically required for a copper test heap, and much more is often used. Kennecott, for example, recently constructed a 0.9 Mt (1 million st) ROM test heap at the Bingham Canyon Mine in Utah. In such coarse ore operations, the ultimate level of extraction will require a leach cycle that can extend from several months to a few years. Quite often, project development schedules do not provide the luxury of mining such large quantities of material or running such long tests. Instead, test data are usually limited to results from column leach studies on relatively fine ore, often with a top size that does not exceed 25 mm. Maximum leach times are also short, typically less than a year before an initial decision is needed on project viability. Proposed method One approach to estimating the recovery from a coarse ore leach is to assume that the leach solution will have some ultimate penetration distance into the rock. Then, the final level of mineral extraction in this "leached rim" will equal the ultimate level of extraction identified in various testing programs. Obviously, if the radius of a given rock fragment is less than the penetration distance, that fragment will be fully leached at the end of the operation. With larger rock sizes, the percent recovery will fall off as the size increases and the fraction of unpenetrated rock mass increases. Such an approach sounds simple but is likely to be complex when applied to a real project. For example, the penetration distance will be a function of both the rock characteristics and the effective length of the leach cycle. The important rock characteristics include rock porosity, the degree of internal fracturing and the mode of mineral occurrence. With regard to the latter, penetration is likely to be greater if the leachable mineralization occurs on fracture surfaces or in veinlets, as opposed to fine grains uniformly disseminated throughout the rock mass. An estimate of penetration distance may be derived from column or heap tests by noting the depth of solution penetration into the larger rock fragments after three, six and 12 months of leaching. While the penetration rate is ore specific, something on the order of 10 to 20 mm/y may be appropriate for competent, primary copper (chalcopyrite) ore. For gold in tight quartz, the rate may be about the same. Copper oxide ores and gold that is hosted in a more porous rock matrix are likely to have penetration rates that are at least two to three times higher, and an even higher rate should be appropriate for uranium hosted in sandstone. As noted above, the length of the effective leach cycle is likely to be measured in years. On this basis, the ultimate penetration distance (dp) would vary from less than 50 to several 100 mm when a particular ore is leached to exhaustion. Several sets of mathematical manipulations are necessary to convert a rock size distribution and corresponding value of dp into an estimated extraction-rate curve. The first step is to break the ROM size distribution down into intervals and then calculate the radius for the mean rock size in each interval. This is shown in Table 1 for rock sizes up to 1.75 m (about 6 ft) in diameter. The next step is to calculate the volume of unleached core and the fraction of rock that is leached. This is done for the following three values of dp: 25, 100 and 250 mm. Results are shown in Table 2. The third step is to select the ultimate level of recovery that will be achieved in the fraction of material that is effectively leached, i.e., the outer zone that is penetrated by the leach solution. This is clearly a site-specific factor that can only come from metallurgical test results on representative ore

Jan 1, 1998

By Tracy T. Morris

The current state of the mining community has made it imperative for operations to reduce costs and increase productivity in order to remain competitive. This has been done in Colorado with the installation of an Outokumpu flash flotation machine for the production of a gold/silver/lead concentrate.

Jan 1, 1987

By D. Gu, B. Lin

Shaft drilling is one of the most useful methods of driving shafts. This paper describes the application and development of the technique in coal mine construction in China.

Jan 1, 1994

By M. A. Bothwell

The purpose of this paper is to describe the methods used to select mill discharge screens, and to outline factors which should be taken into consideration when choosing screens for this application.

Jan 1, 2001

By A. B. Szwilski

The mineability and coal processing costs are influenced largely by the structural and physical properties of the coal seam. The mining process involves coal cutting, pillar support, crushing, and floating. A correlation between the rank, ash content, and coal strength/stiffness is discussed. The coefficient of variability of rebound tests on the face of various coal seams are compared with those of laboratory compressive strength tests by other investigators.

Jan 1, 1988

By Graham G. W. Mustoe, Andrew I. Hustrulid

An advanced numerical model based upon the Discrete Element Method (DEM) has been developed to provide the engineer with unique detailed information to assist in the design of transfer points in large industrial conveyor systems in mining operations. This modeling technique provides a quantitative description of the bulk solids movement through the transfer point. This information consists of the velocity distribution of the bulk solids and the stresses within the bulk solids. The DEM model also gives detailed information concerning the impact forces acting on the transfer structure and the conveyor belts from the bulk solids flow.

Jan 1, 1996

By Boris V. Vlasenko, Vadim P. Potapov, Gennady I. Gritsko

In this paper we consider the elements of an information geomechanic monitoring system which is used in computerized mine planning and mining operations control. The automated sys tem is a technical means of geomechanic monitoring, as a complex system of regulated observations, estimation and prediction of changes in geomechanic state of rock mass and workings during underground mining of coal deposits. Geomechanic monitoring at coal mines and the automated system execute data collection, analysis and calculations of geomechanic situation in the panel during planning, development and carrying-out of mining operations for ensuring geotechnical stability of underground mining.

Jan 1, 1996

Anhydrite-based dam constructions, which have been implemented successfully in other geological formations, were investigated with regard to their suitability in salt mines. The laboratory investigations show that anhydrite-based building materials with suitable additives bind safely in spite of the high temperatures in salt mines which normally pre-vent hydration. The dependence of the compressive strength, swelling behavior, porosity and permeability upon the choice and ratio of binding material components and additives was determined. Based on the results of these investigations, a pilot-scale experiment was carried out at the GSF Research Mine Asse (Germany) using a mixture suitable for the prevailing conditions

Jan 1, 2004