Search Documents

By Steven Atkin, Rens Verburg, Bryony Hansen, David McWharter

The use of paste tailings as underground backfill and for surface disposal is rapidly expanding, and with it comes the requirement to understand and predict its long-term environmental stability. This paper presents the results from a kinetic testing study performed on cemented tailings paste mixtures under both subaqueous and subaerial conditions. In addition, the effects of grainsize reduction are investigated. It will be demonstrated that the long-term weathering behavior of tailings paste is controlled by its physical and chemical characteristics, as well as its placement conditions. The testing indicates that subaqueous disposal of paste inhibits acid generation, whereas the exposed samples produced acidic leachate despite the presence of cement added to meet geotechnical requirements.

Jan 1, 2000

By B. J. K. Sullivan, Brian Hornsby

INTRODUCTION Mount Isa Mines Ltd. operates a copper and silver- lead-zinc property at Mount Isa in northwest Queens- land, Australia. Mount Isa is located in the tropics at latitude 20°43'S and longitude 139°30’E (Fig. 1). It is on the upper watershed of the Leichhardt River and at an elevation of 365 m above sea level. The average rain- fall is 360 mm/y, the greater part of which falls in January to March (the hot summer months). The mean summer temperature for these months is 30°C (dry bulb), with a maximum temperature of 43°C; the mean wet bulb temperature is 25°C with a maximum of 28°C. Mount Isa is located geologically towards the western edge of the Precambrian Shield of northwestern Queensland. This complex forms a north-tilting dissected peneplain which extends in the north-south direction for 640 km, with widths varying from 32 km to 190 km. The combination of differential erosion, regional strike, and steep dips has produced a corrugated topography of low north-south orientated hills and valleys. The field was first discovered in 1923 as a silver- lead-zinc field. Mount Isa Mines Ltd. was formed the following year and subsequently became the sole operating company on the field. Lead and copper ore have been mined and treated separately and simultaneously at Mount Isa since 1953. Intensive exploration commenced in 1954 and an active exploration program provided the justification for a series of production expansion programs in both silver- lead-zinc and copper (see Table 1 ). The most recent and largest production expansion program at Mount Isa commenced when a decision was reached in December 1969 calling for an increase in copper production from 100 000 to 150 000 t/y of blister copper. A major factor which influenced this decision was the substantial additions to the ore reserves in the so-called 1100 ore body which is a massive copper sulfide ore body with a known strike length of approximately 2500 m, a height which is variable up to 300 m, and a width of generally 300 m up to a maximum of 370 m (see Figs. 2 and 3). Host to the copper mineralization is a complex and variable rock generally called "silica dolomite." The ore body strikes 6.02 to 6.1 rad (345° to 350°), dips west between 0.78 and 1.13 rad (45° and 65°), and is truncated at depth by fault implaced basement rocks. It first occurs some 600 m below the surface and bottoms at about 1000 m below the surface. The unconfined compressive strength of the silica dolomite ore varies from 150 to 250 MPa, whereas the basement rocks, carbonaceous mylonite, slaty shale, buck quartz, and greenstone (a chloritic schist) are considerably weaker, varying in strength from 20 to 80 MPa. The distribution of mineralization within the ore body is variable, but can be considered as generally high grade at or just above the basement contact and diminishing towards the upper reaches of the ore body. The current

Jan 1, 1982

By L. M. Yokum

Tremendous strides have been made in front end loaders in the last fifteen years. Fifteen years ago a 2; cubic yard front end loader was the largest standard machine you could purchase. Today there are two commercially available 15 yard front end loaders and many 10 yard front end loaders. The estimated total worldwide market for all front end loaders over one cubic yard has increased to over 30,000 units yearly. The trend for front end loaders, in general, and for the mining market, in particular, is to larger and larger loaders. Today there are 18 cubic yard and a 24 cubic yard front end loader in prototype form. It is not inconceivable that within another fifteen years that there will be front end loaders in the 50 cubic yard class with design features quite different from today's. These larger loaders are being designed at the demand of the mining industry and the design criteria are being directed at this market area. The costs of these larger loaders will be greater per unit of capacity, and it is the intent of the various manufacturers that they will be more reliable, be easier to service, give greater availability, live longer, and cost less to maintain, than previous loaders. It is also the intent of the manufacturers to compete directly with the large mining shovel as the front end loaders become appropriately larger and more reliable. There has been some trend in this direction in the past with smaller shovels and loaders. In Figure No. 1 are data for U.S. production of front end loaders (5-6 cubic yard class and 10 cubic yard class) and U.S. production of cable operation, crawler mounted power shovels, draglines and cranes (1; to 5 cubic yard class) for the years 1965 and 1970. (Source: Bureau of Census, U.S. Department of Commerce.)

Jan 1, 1972

By David Brown, Glen Hall, Ken DeVos, Frank Barone

Dredging and Flooding was completed on the Falconbridge Limited "New Tailings Area" in the period from 1996 through 1998, as part of their site closure measures. Part of the decision making process and closure planning was water quality prediction, including oxidation and diffusion modelling. The purpose of this modeling was to define the potential water quality that would result during and after dredging. A significant body of research on the geochemistry and oxidation kinetics of this site had been compiled. The results of the modeling provide practical insight on the potential water quality that may be expected. Water quality in the pond has steadily improved since flooding was completed with the exception of short term peaks during spring runoff. Aquatic vegetation is appearing through natural recovery and transplanting of local species, and colonies of minnows are now observed in the ponds.

Jan 1, 2000

By X. Wu, M. G. Karfakis, K. Y. Haramy, B. T. Brady

A quantitative evaluation of damage caused by ground motions associated with strong roof caving is presented. The strong roofs are modeled as either cantilevering or bridging beams over continuous elastic foundations that are subject to an exponentially distributed vertical stress. Major factors influencing roof caveability and strain-energy buildup are identified and investigated. A methodology for the evaluation of strain-energy accumulation caused by, an overhanging roof is presented. The potential for mine tremors is determined in terms of the local Richter magnitude (ML), which depends on the seismic energy transformed from the stored strain energy that is released when the roof fails. A particle-velocity model is applied to estimate the damage area associated with roof collapse. A case study from a Utah coal mine shows that estimations of bump severity and the damage area agree well with field observations.

Jan 1, 1997

By Randal J. Barnes, Franck Rellier

Mine ventilation survey data includes generally redundant, usually inconsistent, often incomplete, and always noisy measurements. Yet, these data are essential for operational decisions and represent the foundation of any mine ventilation systems model used for future engineering analysis and design. For example, the basic ventilation network geometry can be measured with a reasonable precision, the network flows can be measured, but with significant errors, and the branch resistance factors can not be directly measured at all. The network-based, constrained weighted least squares approach, presented in this paper, advances a method for the sys tem-wide adjustment of ventilation branch measurements and the consistent estimation of global system parameters (e.g. branch flows, head losses, and resistance factors). The constraints guarantee that the adjusted values satisfy the governing physical laws: conservation of flow, conservation of energy, and the appropriate energy dissipation rule (e. g. Atkinson's RQ2). The weights allow for the proper inclusion of data with widely disparate precision, as well as offering a simple method for retiring old data as the mine changes through time. The post-adjustment sensitivity analysis presents two potentially useful forms of analysis: the identification of previously unspecified leakage branches, and the semi- automatic recommendation for future ventilation measurement campaigns. The overall efficiency of the algorithm is exemplified by the fact that a ventilation network with hundreds of branches and thousands of measurements can be routinely adjusted on a microcomputer.

Jan 1, 1989

By Natarajan K. A.

During sulphide ore grinding, electrochemical interactions between grinding medium and the minerals play a significant role in bringing out enhanced ball wear on the one hand and alter the surface property of the ground minerals on the other. The role of the flotation reagents added simultaneously during grinding with respect to ball wear as well as flotation is yet to be established. Electrochemical measurements such as rest potential, combination potential and galvanic current between sulphide mineral and ball material couples have been carried out in the presence and absence of flotation reagents to understand the nature of electrochemical interactions between ball material and sulphide mineral. Electrochemical mechanisms and models have been proposed to explain the role played by the flotation reagents during different binary, ternary and quaternary interactions with respect to ball wear during grinding.

Jan 1, 1992

By William Gleason

"Once the primary fuel source for the United States and the economic backbone for communities from Appalachia to Wyoming, coal has been on a steady decline since the mid 1990s, and is now at the center of political debate in the United States.The political spectrum of the United States is divided on the future of coal and its place in the energy sector. The coal mining industry and the communities that rely on coal have increasingly been pitted against forces that wish to regulate coal to the history books.In 2008, President Obama launched what many have called his war on coal, and during his eight years in office, he pushed through numerous pieces of regulations and legislation and that he said were aimed at reducing carbon emissions, but that others viewed as direct assaults on the domestic coal industry. Obama led the United States delegation to Paris to sign the Paris Accord in 2016, a 196-country agreement pledging that the United States would do its part to reduce carbon emissions. His administration also instituted clean air, power and water regulations that added extra environmental burdens to many industries, but perhaps none more so than the coal industry.In this month’s lead feature, “A study of U.S. coal mine closures since 1994” (page 18), the impact of the war on coal, and other factors, can be seen in text and figures. Author Jacob Brinkman and coauthors Jay Schafler and Catherine Johnson scoured the data of the U.S. Energy Information Administration (EIA) and the U.S. Mine Safety and Health Administration (MSHA) to show how coal production and mines have been impacted since 1994 and how the years 1994 to 2000 and 2008 to 2016 were particularly hard on the industry.For example, in 1994 there were 2,354 coal mines in the United States. Currently, there are 1,035 mines in operation.In 2016, then candidate Donald Trump promised to end the war on coal and to put coal miners back to work. In 2017, President Trump has followed up on those promises. He announced plans to withdraw the United States from the Paris Accord, signed an executive order designed to undo the Clean Power Plan put in place by President Obama, halted the research on the health effects of mountaintop removal coal mining, directed the U.S. Environmental Protection Agency (EPA) to revise the guidelines of waste water from power plants and has touted that more than 1,000 coal miners have returned to work since he was elected."

Jan 9, 2017

By Neville G. W. Cook, John Kemeny

Utilizing the principles of elastic-brittle fracture mechanics, stress-displacement relationships are derived for an elastic solid containing a slip plane consisting of various configurations of collinear arrays of cracks. These models take into account the heterogeneous nature of slip planes as observed in the lab and in the field, and are relevant to the behavior of rock containing faults, joints, bedding planes, and fractures. All of our models exhibit slip weakening behavior, and show regimes of both stable (aseismic) and unstable (seismic) deformation. For given configurations of cracks and applied boundary conditions, our results show explicit ly the energy released through unstable crack growth. For instance, it is found that two equal length cracks growing together release more seismic energy than, say, a large crack growing into a small crack. Also, by allowing cracks to coalesce, our models show multiple stick-slip events without crack healing or other geochemical means.

Jan 1, 1986

By R. A. Holmes

Although manganese is a metallic element and is widely dispersed in nature, it never occurs except as a compound in combi¬nation with other elements. Use of such compounds in the production of glass is known to have occurred in early Egypt. The dioxide of manganese was considered a compound of iron until 1774 when C.W. Schule first recognized it as an element. In the same year, a Swedish mining engineer, J.G. Gahn, became the first to isolate manganese. In 1856 development of the Bessemer process of steelmaking gave economic importance to manganese, and later, in 1882 Robert Hadfield discovered the benefits of high manganese steels. GEOLOGY Physical Properties Elemental manganese is a silver-gray metal, resembling iron but harder and more brittle and used primarily in alloys (both ferrous and non-ferrous) and a wide variety of chemical compounds. Some of the physical properties of manganese include: melting point¬1 245°C; boiling point-2 150°C; density at 20°C-7.43 g/cm3; specific heat at 25.2°C-O.115 cal/g; latent heat of fusion-63.7 cal/g; hardness on Mohs scale-5.0; linear coefficient of thermal expansion from 0 to 100°C-22 x 10-6. Mineralogy There are over one hundred minerals that contain manganese. These minerals vary from those with compositions that are pre¬dominantly manganese to those having only minor percentages of manganese. Distribution of Deposits Manganese ore deposits are found worldwide and were formed in various geological environments, but only a rather limited num¬ber of deposits have high grade manganese ore in sufficient quan¬tities to be mined and utilized economically on an industrial scale. It is worth noting the fact that almost all of the significant deposits can be classified into two types of deposits: marine chemical sed¬imentary deposits, and residual (secondary) enrichment deposits. There are, however, a much larger number of geological types but these are not of commercial significance at this time. Sedimentary deposits are the most common and are usually stratiform or lenticular. Manganese minerals were formed by a chemical process during the deposition of marine sediments. They usually contain manganese oxides and carbonate minerals, some¬times interbedded together or with other sedimentary rocks such as limestone or shale. Examples of this type of deposit are the Russian ore bodies of Nikopol and Tchiatoura, as well as the Kalahari deposits in South Africa and deposits of Groote Elyandt in Aus¬tralia. Residual deposits were formed in a different way: by alteration of existing manganese deposits or by concentration of the manga¬nese minerals when other minerals were washed away by weath¬ering or ground water processes. The Nsuta deposit in Ghana, the Amapa deposit in Brazil, the Moanda deposit in Gabon, and nodules in the residual clays of the US Southern Appalachians are examples of this type of geological process. In the case of the Ghana and the Amapa deposits, this is only true for the outer layers of the deposit containing oxide minerals, the inner part being comprised of car¬bonate minerals including manganese carbonate, probably from marine origin. Some sedimentary and residual-type deposits have been metamorphosed, giving rise to small high grade ore bodies. These deposits are regionally metamorphosed, occurring in mar¬bles, slates, quartzites, schists, and gneisses. Some of these deposits, such as the Franklin, NJ, deposit are rich enough to be commercial without secondary enrichment; however, most of the exploitable deposits have been secondarily enriched. Due to the diversity and complexity of manganese deposits, both with respect to deposition and chemistry, a wide range of impurities are almost invariably present in the ores. Table 1 shows that the reserves (i.e., a measured resource that can be economically and legally extracted) are estimated at 814 x 106 tons of contained Mn, which equates to more than a 100 year supply at the current level of production. The reserve base is made up of the marginally economic reserves and sub-economic re¬sources and are some 4.5 times greater than the proven reserves. Also apparent from study of Table I is the fact that some 75% of manganese reserves are found in two countries, the USSR and South Africa. On the other hand, North America (i.e., the United States and Canada) have few significant deposits. The largest deposit, or at least one of the largest, in the United States is located at Chamberlain, SD. This deposit is sedimentary

Jan 1, 1994

By Richard J. Goff

Technical Support, one of several major organizational units in the Mine Safety and Health Administration, provides technical assistance to the mining community in all areas of health and safety. One of its many areas of expertise is noise control. Depending upon the needs of the operator or inspector, the services provided can range from locating major noise sources to actually building noise controls. Over the years a vast amount of knowledge has been obtained as to what will work and what will not. DESIGN GOALS While many noise controls have been developed for mining equipment and operations, the most acceptable (ergo successful) have achieved the following design goals: - a noise level reduction of at least 5 decibels; - minimum interference with production; - inexpensive to install; and - effective in reducing low frequency noise.

Jan 1, 1984

By C. Tompouloglou

The innovation in a technological field is reflected by the Research and Development (R & D) activity in it. It is explained why patent literature is a more reliable indicator than non-patent literature for the assessment of the R & D activity in the technological fields considered. Consequently the R & D activity is measured in this article through the patent applications filed in the fields considered. The pattern of patent application filings in Drilling, Mining, Tunneling and accessory technologies is analyzed at an international scale over the period 1990-2000. A statistical analysis of the fluctuation of the number of patent applications per year, per country and per technological field is performed. The technological fields are defined on the basis of the internal patent classification used in the European Patent Office. The article attempts to detect the high activity and ?cutting edge? technologies over said period, to relate them to political or financial events and possibly to foresee the ?cutting edge? technologies of the future in which potential investors could be successful. Strong patents are revealed on the basis of the frequency of their citations by the applicants in patent applications or by the patent examiners in the search report. International as well as specific national trends in the innovation are spotted and analyzed.

Jan 1, 2003

By Mona M. Fawzy, Ahmed A. Eliwa, Ebrahim A. Gawad, Ahmed H. Orabi, Amal E. Mubark

The growing demand for rare earth elements (REEs) has led to numerous recent studies to recover these elements from various bearing ores and wastes. Therefore, the recovery of REEs from Ras Baroud polymetallic concentrate has been investigated in the current study. Physical beneficiation for the Ras Baroud pegmatite sample was carried out, yielding a concentrate for euxenite (Y), fergusonite (Y), xenotime (Y), monazite (Ce), allanite, thorite, uranothorite and Hf-zircon, which resulted in raising the concentrations of REEs, Th, Zr, U and Ti in the sample. Fusion digestion processes with sodium hydroxide were studied using the conceived predictive diagonal (CPD) technique. The three experimental digestion groups proved the dissolution of 99.9, 95.6, 99.9, 52.5 and 0.47 percent for REEs, Th, U, Ti and Zr, respectively, under fusion conditions of 723 K, 120 min, 1/1.5 ore-to-alkali ratio, and smaller than 100-μm particle sizes. Fusion kinetics, isotherms and thermodynamics were investigated using several suggested models, namely, pseudo reversible first order, uptake general model and shrinking core model, which matched well with the experimental digestion results. Selective recovery of actinide content from the REE content of the digested concentrate chloride solutions was accomplished using solvent extraction with di-2-ethyl hexyl phosphoric acid. About 99.9, 99.9 and 4.2 percent extraction efficiencies for Th, U and REEs were realized, respectively, using 0.3 mol/L solvent concentration in kerosene as a diluent, 1/2 organic-to-aqueous ratio, aqueous pH of 0.2 and contact time of 15 min. Thorium and uranium ions were stripped with 2.5 mol/L sulfuric acid solution with 94 and 98 percent stripping efficiency, respectively. A highly purified REE precipitate was obtained from the raffinate solutions. Zircon mineralization tailings were obtained as a byproduct through the alkaline digestion process.

Oct 1, 2024

By J. E. Gebhardt, D. W. Fuerstenau

The use of small quantities of polyacrylic acid (PAA) was found to significantly improve the flotation of fine-sized hematite particles at pH 4.1 and 0.001 M NaCl with sodium dodecykulfonate (SDS). Low polymer dosages before collector addition aid flotation by forming flocs of primary particles, but excess polymer results in low flotation yields due to surface saturation by the hydrophilic polymer. Contact angles, measured on a hematite disk, substantiate the hydrophilic nature of an adsorbed polymer film. Pre-adsorbed PAA reduces the amount of SDS adsorbed on the hematite particles, but the flotation of hematite flocs occurs, even at reduced amounts of adsorbed SDS, and is not depressed until PAA dosages in excess of the saturation value are used. Separation of a hematite-quartz mixture can be achieved by SDS flotation of PAA,-flocculated hematite. Maximum selectivity results with the addition of small quantities of PAA, while excess polymer is detrimental to the recovery of hematite. Consecutive flotation states on a single feed yield a higher grade hematite product at some expense to the overall recovery.

Jan 1, 1987

By Stanley C. Suboleski, C. B. Manula

INTRODUCTION In any mining operation all possible steps should be taken to increase efficiency. One area for improvement is mine planning and design, particularly in the area of equipment selection for room-and-pillar systems. Be- cause of the availability of a wide variety of face machines, a fair degree of selectivity can be exercised in the choice of equipment for a particular job. However, this choice must be made on the basis of quantitative facts and forecasts related to the mining application. The purpose of this section is to develop and analyze the details of the mining process. Some specific areas studied include the relationship of system design to productivity, suboptimization as a result of equipment changes, and measurement of system performance. The plan of work leading to a quantitative description of these study areas is based on the growing interest in total system design using simulation as an analytical method (Manula, 1963). CHARACTERISTICS OF PRODUCTION OPERATIONS FROM ROOM-AND-PILLAR SECTIONS For a given mining method, raw production in a given section of a mine is primarily dependent upon the coal seam thickness, roof and floor conditions, methane emission, the mining methods, and the man-machine element. Average section production varies from 300 to 800 st per shift for conventional and continuous mining in high seams and from less than 100 to 300 st per shift in low seams. Since the reject varies from 0 to 40%, these figures must be decreased by the appropriate percentage to reflect the amount of clean coal mined. Personnel requirements per production section per shift for the various methods are listed in Table 1. Table 1. Production Personnel Method No. Method No. Conventional 12-1 5 Longwall 9-14 Continuous 9-1 2 Shortwall 9-12 MINING VARIABLES To evaluate the constraints and interrelationships for various mining methods, it is necessary to categorize the variables which underlie system production potential. Seven critical independent variables which determine production can be identified and categorized (Suboleski, 1978) : Seam Height The five categories are as follows: less than 36 in.;. 36 to 55 in.; 55 to 100 in.; 100 to 180 in.; and greater than 180 in. Floor Quality Floor quality ranges from : Excellent: Smooth, hard, grades less than 1 to 1 % % , and dry. Good: Smooth, soft but dry, with grades less than 3 % . The floor will deteriorate, but cautious operation can prevent it. There may possibly be heaving at some later time. Fair. Soft and damp. There is occasional interference with equipment operation; requires the use of four-wheel drive shuttle cars; ruts with regular use, and may have adverse grades of 5 to 7%. This may be coupled with slippery bottom and/or occasional steep rolls. Poor: Soft and wet. Requires blocking of the bottom to support equipment. There are frequent steep rolls and grades in excess of 7%. Roof Quality Roof quality ranges from : Excellent: Men are able to work under the unsupported top during the initial production cycle if legally permitted. Good: The roof is bolted on a 4 x 4 or 5 x 5 pattern with short bolts (442 in.) or <seam height if the seam >42 in., or requires posting with no bolts on a 4 x 4 or 5 x 5 pattern. There are no falls. Average: The roof is normally bolted on a 4 x 4 or 5 x 5 pattern, but with long bolts (>seam height or >6 ft.). There are infrequent minor falls or there may be an excellent roof which is difficult to drill. Fair: This type often requires spot bolting in addition to the regular pattern or bolting with planks. The roof conditions require shorter than planned cuts, or narrow cuts. Poor: This type requires bolts plus crossbars and posts, or installation of yielding supports or truss-type support. It is almost certain to fall if this is not done. Methane Liberation This ranges from none detected to low (no buildup at the face, even with minimum ventilation requirements) to moderate (the curtains must be extremely tight and tubing close to the face or methane will build up to 1 % during the loading of the car) to high (methane will build up to 170 if the miner is operated at the normal rate, even with proper ventilation). Hardness of Coal Coal hardness falls into the following categories: Soft: Soft coal is easily cut by a continuous miner. A plow could be used by longwall. Average: Coal of average hardness could be easily cut by a miner, and a shearer would be used in the longwall. Moderate: Moderately hard coal causes difficult cut-

Jan 1, 1982

By K. Fuenkajorn, S. Serata

Discussion by S. Serata and K. Fuenkajorn Background Results of the above study in the August 1991 issue of Mining Engineering offer valuable lessons in the solution of cutter-roof problems. The original study plan was initiated by the discussion authors to solve the problems using the "stress control method" of mining (Serata 1976, 1982; Serata, Carr and Martin, 1984; Serata and Gardner, 1986; Serata, Gardner and Preston, 1986; Serata, Gardnerand Shrinivasan, 1986; Serata and Kikuchi, 1986; Serata, Preston and Galagoda, 1987) However, the plan and the planner were changed to the arrangement reported in the paper. The change was considered reasonable at the time due to the mine engineers&apos; uncertainties about the stress control method. Consequently, the basic principle of the study was shifted from the original stress control method to the method described in the paper, which will be called the "yield pillar method" for the purposes of this discussion. The paper convinces the reader that the yield pillar method fails to solve the cutter-roof problems. This doesn&apos;t mean that the stress control method also fails. Actually the contrary is true, as discussed below. Limitation of the yield pillar method The paper illustrates clearly how poorly the yield pillar method performs in solving the problem. The reason for this failure is the lack of the protective stress envelope needed to stabilize the cutter roof. Unfortunately, the protective envelope cannot be formed properly without utilizing the stress control method of mining. Changing the pillar size does not make much difference in the roof stability. Stress measurement The key issue is how to form the global stress envelope to make the gate entries safe for production. Therefore, measuring the stress condition of the ground around the mine opening is critically important to solving the cutter-roof problem, regardless of the method applied. With regard to the stress measurement, there is a serious question as to the reported stress state of [6 i = -51.7 MPa (-7499 psi), G2 = -44.5 MPa (-6458 psi) and 63 = -30.8 MPa (-4465 psi)]. It is mechanically impossible to have such a stress state at any location in the mine ground since the known initial vertical stress [o,,] is less than or equal to 800 psi. There may be a large stress state in the [61] direction, but that is possible only at the expense of the [63] value. Having the above stress tensors in the mine is simply impossible. The questionable, reported stress values could be attributed to the application of the overcoring method, which tends to produce erroneously large stress values in the extremely nonelastic mine ground. Stress control method The paper should be considered as a major contribution demonstrating the limitation of the yield pillar method. At the same time, the paper does not disprove the stress control method. However, in comparing the paper with stress control studies conducted in other similar failing grounds, the stress control method appears to be able to solve the problem more effectively. Therefore it is advisable that the mine not give up its efforts to solve the problem. [•] References Serata, S., 1976, "Stress control technique - An alternative to roof bolting?," Mining Engineering, May. Serata, S., 1982, "Stress control methods: Quantitative approach to stabilizing mine openings in weak ground," Proceedings, 1st International Conference on Stability in Underground Mining, Vancouver, BC, Aug. 16-18. Serata, S., Carr, F., and Martin, E., 1984, "Stress control method applied to stabilization of underground coal mine openings," Proceedings, 25th US Symposium on Rock Mechanics, Northwestern University, June, pp. 583-590. Serata, S., and Gardner, B.H., 1986, "Benefits of the stress control method," invited paper, American Mining Congress Coal Convention, Pittsburgh, PA, May 7. Serata, S., Gardner, B.H., and Shrinivasan, K., 1986, "Integrated instrumentation method of stress state, material property and deformation measurement for stress control method of mining," invited paper, 5th Conference on Ground Control in Mining, West Virginia University, Morgantown, WV, June 11-13. Serata, S., and Kikuchi, S., 1986, "A diametral deformation method for in situ stress and rock property measurement," International Journal of Mining and Geological Engineering, Vol. 4, pp. 15-38. Serata, S., Preston, M., and Galagoda, H.M., 1987, "Integration of finite element analysis and field instrumentation for application of the stress control method in underground coal mining," Proceedings, 28th US Symposium on Rock Mechanics, Tucson, AZ, pp. 265-272.

Jan 1, 1993

By Deepak Malhotra, Linda K. Baltich

The minerals business is dynamic and competitive and the economic viability and/or profitability of any mineral company depends on maximizing recoveries while minimizing costs. In order to achieve this goal, it&apos;s essential that you have a clear understanding of the current status, including strengths and weaknesses, of the operation. The authors have developed a systematic approach to plant auditing which we have used successfully at several operations. The strategy presented in this paper can be tailored to fit a wide range of audits. This flexibility is a key feature of the approach.

Jan 1, 1989

By Y. G. Zhang

Interactive Dynamic Optimization Method (IDOM) will be presented in this paper. IDOM combines inventory theory, dynamic programming, computer simulation and interactive technique to formulate a production schedule for open-pit mines. This new method has been successfully used in metal mines of China for years.

Jan 1, 1986

By Howard J. Brown

The Lucerne Valley limestone mining district is in the San Bernardino Mountains, one of the major ranges in the Transverse Range Province of southern California. Several large limestone mining operations are present along the north range front in Lucerne Valley, and the area is one of the premier limestone mining districts in the country. Resources are contained in Paleozoic carbonate rocks that are part of a thick late Precambrian and Paleozoic sequence that uncomformably overlies crystalline basement. The district has been affected by multiple episodes of metamorphism and deformation, as well as by a complex sequence of late Cenozoic structural events. Detailed studies, however, have demonstrated that these rocks can be divided into formations correlatable with late Precambrian to Permian strata of the Cordilleran miogeocline. The district is the leading producer of white, high-purity calcium-carbonate products in western North America. Pluess-Staufer (California) Inc. mines and processes high-purity white limestone from extensive deposits, and is one of the largest producers of high-quality limestone fillers and extenders in the western United States. Major factors influencing the genesis of economic carbonate deposits in the district include depositional environment, post-depositional processes such as diagenesis, dolomitization and/or silicification, regional and/or contact metamorphism and associated intrusive activity, faulting, folding, uplift and erosion, and preservation from erosion. Regional geologic studies, detailed geologic mapping, intimate knowledge of stratigraphy, and recognition of complex structural relationships have proven to be invaluable tools in the discovery of high quality calcium carbonate deposits in the district.

Jan 1, 1987

By Kumara Rachamalla

North American mining companies are lagging behind their global competitors in participating in the outstanding opportunities in India. The Indian government has liberalized foreign equity participation in the mining sector by up to 50% and, in some cases, even higher. Delegates from Europe, North America and South Africa learned this at an information seminar held in London, England, Attendees were welcomed by L.M. Singhvi, the UK&apos;s high commissioner for India. He introduced a government of India delegation headed by B.P. Baishya, minister of steel and mines. Singhvi is an eminent jurist and leading constitutional expert. He reiterated the soundness of India&apos;s legal system. He also outlined the recent Investment Protection Treaty between India and the United Kingdom. Baishya emphasized thee geological diversity and strengths of India&apos;s domestic market with its population of more than 920 million people the second largest in the world after China and its reservoir of skilled labor. He also outlined the potential of India&apos;s untapped natural resources. The private sector is the backbone of the Indian economy. It accounts for 75% of gross domestic product (GDP). The current minimum program of the new United Front government envisions 12% growth in the industrial sector, 7% in GDP and direct foreign investment of US$10 billion a year. "Mining is an area that can attract a sizable part of this investment," Baishya said. "Projected growth of the Indian economy will require increasingly large quantities of basic raw materials, such as coal and base- and precious-metals to meet the needs of domestic and export markets." Administration of India&apos;s mining sector is divided into the Ministry or Mines for regulating and developing the country&apos;s mineral resources, five public sector Mining Enterprises, the Geological-Survey of India (GSI), the Indian Bureau of Mines (IBM)and 25 states and seven Union Territories. The GSI is the second oldest (founded in 1851) and the third largest organization of its kind in the world, Baishya said. It has geologically mapped more than 90% of India&apos;s 3.2 million kmz (1.2 million sq miles) at a scale of 1:50,000. Several promising mineral projects have emerged from regional exploration programs conducted by GSI and the Mines and Geology State Governments. IBM recently completed a national mineral inventory. It covers 13,000 deposits/prospects of 61 nonferrous minerals. GSI also compiled a similar inventory on 61 coal fields. India is attractive to exploration companies for several reasons. These include favorable geology, accessible locations and a large mineral database. India also has many experienced geoscientists with well-equipped and efficient laboratories, Baishya said. Secretary to the Ministry of Mines A.C. Sen emphasized the largely untapped-geological and mining potential of India. He also discussed the new vistas that have opened up opportunities for exploration and mining. India has large quantities of mineral reserves, Sen said. Its vast Precambrian Shield - like those in Canada and Australia - is endowed with gold, platinum group and base metals, as well as coal and industrial minerals. Annual mineral production is valued at more than US$7 billion. Sen pointed out that India is the largest single consumer of gold. And domestic gold prices command at least a 20% premium above international prices. Recent diamond, gold and base-metal discoveries and prospects uncovered by GSI have generated investment interest from abroad, he added Delegates heard that the Indian Constitution gives the central government the job of framing legislation and the regulation and development of minerals. This ensures that mineral laws are uniform throughout the country. However, the right to grant mineral concessions, such as prospecting licenses and mining leases, rests with the minerals&apos; owner. In India&apos;s case, that is the state government. The Indian government has formulated several guidelines that regulate the granting of prospecting licenses for large areas. ? The central government will consider the requests of state governments for the granting of prospecting licenses for areas exceeding 25 kmz (9.6 sq miles). But the license must include a provision to conduct aerial prospecting of the area. ? Any prospecting licensing area should not exceed 5,000 kmz (1,930 sq miles). for a single license. And the total area held by one company should not exceed 10,000 km2 (3,861 sq miles) for the whole country. ? The grant of larger areas will be linked to a mini- mum expenditure commitment on physical targets. State governments will monitor these expenditures. ? The granting of large areas for prospecting will be linked to a schedule of relinquishment.

Jan 1, 1997