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By Brad C. Lewis

The coal mining industry has experienced a general trend toward longwall operations. An increasing percentage of underground coal is being mined by longwalls. And productivity in longwalls is likewise increasing. Operators of longwalls, however, have not yet reached a state of mining euphoria. Competitiveness within the industry and from alternate fuel sources is forcing continued pursuit of higher productivities and lower costs. [Figures 1, 2 and 3] present trends in the industry. Longwall mines, as defined here, are those reportedly having longwall installations in each of the respective years. Production from both the continuous miner and longwall units is included in the longwall mines. Nonlongwall mines are all other underground mines. Productivity calculations are based on total employee-hours associated with the operation. Annual percent increases in productivity appear to have peaked in the 1985-1987 time frame. This was due, in part, to implementation of technological advancements and improvements in management-labor relations. The results shown in [Fig. 3] aroused the author's curiosity. The first question was "Have technological advancements to increase productivity peaked?" It does not appear so.

Jan 1, 1990

By Merwin Bernstein

Peru has been an important source of metals since Aug. 29, 1533. On that day Francisco Pizarro took charge of the 24 t (772,000 oz) of gold and silver that constituted Atahualpa’s ransom. At today’s prices, the value of that booty ranges between $100 and $150 million, depending on the proportion of gold to silver. Since then, Peru’s silver and gold production has been legendary. Current mine production Most of Peru’s metals are mined from the Andes Mountains and its foot-hills. The Andes run the length of the country parallel to the Pacific coastline from Ecuador to Chile, a distance of nearly 3000 km (I 875 miles). They are about 300 km (187 miles) wide and much of the range is more than 3000 m (9900 ft) in elevation. High plateaus (altiplanos) occupy a large part of the range. Both flanks are rutted by large valleys and canyons. Many of these peaks are prodigious. which make road building expensive and adds to the cost of mining.

Jan 1, 1993

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 Manfred Jaeger, Klaus Ertmer, Walter Dietrich, Jochen Greinacher, Wilhelm J. Kogelmann

In Europe, novel low-cost excavator-mounted Multi Tool Miner (MTM) systems, consisting of cutter head, hammer, bucket and drill attachments permit one unit to perform multiple tasks replacing several purpose-built machines. At the Weser Tunnel in Germany, cross-passages between the twin tubes were excavated in frozen ground with a remote-controlled mini-excavator equipped with a quick-change cutter head, ripper tooth and bucket. In Switzerland at the N2 interstate near Basel, W. Dietrich AG enlarged a 2-lane tunnel to three lanes with a cutter head mounted on a special excavator. Blasting and heavy hammers were not permitted due to the closeness of the “live” twin tube. At the N20 Zurich bypass, the Joint Venture of Jaeger, Frutingerand AHB excavates highway tunnels, some with extremely large cross sections, conventionally. A cutter head mounted on an excavator removes the rock shattered by blasting precisely to the pay line, thus preserving the rock’s self-supporting capacity preventing subsidence and damages to water resources and buildings on the surface under low overburden.

Jan 1, 2003

By Tim Avery, Steve Klein, Mark Schmoll

Tunnel boring machine (TBM) performance in hard rock is highly dependent on the geologic conditions, including the type of rock and hysical properties like the rock strength, hardness, and the spacing of the fractures. This paper examines TBM performance relative to the geologic conditions and rock mass properties at four recent TBM-bored tunnels in California.

Jan 1, 1995

By Ahmed I. A. Salama

The problem of estimating separation characteristics by utilizing mass distributions of feed and products is considered. The separation characteristics include mass yield and partition curve. The cases of mass balance and partition functions balance are identified. The developed techniques can handle the cases of two- and three-product separation. Actual data are utilized to demonstrate the proposed techniques.

Jan 1, 1992

By R. F. Shurtz

This paper uses a simple model to illustrate the fact, widely known to information theorists, that the covariogram represents only half the information in the data used to construct it. It suggests and illustrates methods of putting the other half to use in describing mineral deposits. It also identifies applications in which the phase information is not needed.

Jan 1, 1986

By J. Z. Cheng

The extraction of thorium from industrial radioactive wastewaters discharged from Rare Earth (RE) plants was studied by the liquid membrane emulsion technique using P507- Span80-sulphonating kerosene-HCl. The emulsion conditions, the technological factors such as ratios of oil to the internal aqueous phase and water to emulsion, and the extraction time etc. were investigated.

Jan 1, 2008

By D. K. Grubbs

Red bauxites from Breadnut Valley, Clarendon Parish, Jamaica, are very homogeneous in texture. Bauxite minerals are uniformly distributed in a groundmass, the predominant grain size being smaller than l um (Figure 1 Although the deposits have a massive, non-stratified structure, they all seem to have been affected by postformational faulting which is evidenced by shear zones running subvertically through the deposits. These shear zones stand out very clearly because of a yellow staining along their faces. Often yellow zones, ranging from a few m to several cm in thickness, have developed. When the shear zones are cut at an angle, they appear as yellow veins. Near the surface of the deposits, yellow material forms shallow irregular lenses (Figure 2). In most cases, tree roots (hair roots), or their imprints, are associated with the shear zones or stained areas. In fact, the yellowish color is especially pronounced along these roots and often disappears where the roots end (Figure 3). The mineral composition and texture of red groundmass and yellow zones are markedly different. Secondary phosphate minerals and a higher goethite to hematite ratio characterize the mineral composition of the yellow zones. It should also be noted that Al-substitution in goethite from these areas is significantly higher than in goethite occurring in the groundmass (Figure 4).

Jan 1, 1980

By Lorraine B. Yde

Successful implementation of computer systems deals with meeting final systems objectives and cost and schedule requirements, but the final success is dependent upon personal inter- action. This is a case history of the installation of responsibility reporting at The Anaconda Co.'s Twin Buttes operation, later to become Anamax. The study has been documented as it occurred in hopes that it will illuminate the "people" side of computer systems implementation. Systems implementation involves negotiating with people. "The cooperative approach to negotiation (Nierenberg, 1968) the approach which vostulates that all varties must come away having gained something is based on a simple but important premise. Negotiation takes place between human beings. You cannot negotiate with a computer." This is a look at the human side of a major system installation. An attempt is made to show how a reporting system enabled a company to take a new look at itself. It is also an example of statements made by Toffler (1970) in Future Shock. "As machines take over routine tasks and the accelerative thrust increases the amount of novelty in the environment, more and more of the energy of society (and its organizations) must turn toward the solution of non-routine problems. This requires a degree of imagination and creativity that bureaucracy, with its man-in-a-slot organization, its permanent structures, and its hierarchies, is not well-equipped to provide."

Jan 1, 1979

By John D. Katsllometes

In the mining and processing industry, the maintenance plan has often evolved rather than being consciously set up resulting in an overreliance on breakdown and fixed-time maintenance (planned maintenance). Historically mining and processing plant equipment has been robust and less automated than modem equipment, making it relatively easy to work on. Mining and processing plants have relied on large and expensive maintenance departments to enable rapid attention to breakdowns. Maintenance itself can result in excessive downtime and costs. This results from the requirement to take the machinery off-line to carry out (possibly unnecessary and invasive) maintenance. The danger of infant mortality after it has been put back on line again and also the cost of the maintenance action itself contributes to costs. A goal of any well-run maintenance program is to have the lowest cost while providing 100% capacity 100% of the time to operations. When maintenance investments are at a minimum, the cost of lost production is at its highest. As maintenance effort and investments are intelligently increased, the production loss gradually decreases until the lowest combined cost is achieved. This is the maintenance goal. A road map is needed to achieving maintenance excellence. This article addresses a "Road Map" to achieving maintenance excellence. INTRODUCTION Mining and processing industry maintenance is big business. A world-class maintenance program is characterized by maintenance excellence.

Jan 1, 2004

By Joseph T. Matoney, Okley B. Bucklen, Claude A. Goode, Philip G. Meikle

INRTODUCTION Annual coal production rose to over 1.03 billion st (931 Mt) in 1990. At the same time the number of mines producing this increased tonnage has decreased over 60% in a 30-year period, from 9230 mines in 1960.1 The great increase in production made possible through continued mechanization requires greatly improved loading facilities just to get coal away from the mine. Also the trend to combine production from more than one mine and cleaning it in a single preparation plant continues. A recent census of US coal preparation plants indicated that 310 plants were in operation.2 In addition to increased loading capacity, storage and blending facilities are more necessary both at the producer and user end. In this climate of rapidly changing technology, any written account is faced with the possibility of obsolescence before its appearance. Thus, this chapter seeks to define the common and current practice in coal loading and storage facilities with the full knowledge that this practice is an ever-moving target. FUNDAMENTALS OF COAL STORAGE Storage of coal is becoming an increasingly important part of coal handling systems at mines, particularly since the advent of the unit-train concept in transportation. In order to take advantage of reduced transportation rates on trainload shipments of coal offered by unit-train movement, operators have found that storage is an economic necessity. In unit-train practice, large predetermined quantities must be loaded in relatively short periods of time, as opposed to conventional practice where coal is loaded at a speed dependent on the production capacity of the mine and/or the cleaning capacity of the preparation plant. Clean coal storage is generally practiced in order to accomplish one, or a combination, of the following objectives: 1. To load out promptly and economically. 2. To facilitate blending in order to even out chemical and physical inconsistencies and to prepare desired products or to attain maximum product uniformity. 3. To store certain sizes whose prices and market demand fluctuate with seasons and to permit shipping in good weather. Coal storage, then, is necessary and desirable, both from production and utilization standpoints. There are, however, several undesirable aspects attendant to the storage of coal, the most important of which are oxidation and spontaneous combustion, changes in properties which may affect utilization of the coal, degradation of coal due to rehandling, and the added cost of handling and storage facilities.

Jan 1, 1991

By D. Nilsson

This paper demonstrates the importance of including a discount rate in the determination of the optimum final depth of an open pit. Without a proper discount rate, a pit will probably end up too deep. Another consideration is future underground mining. If underground mining is profitable, the pit may need to be shallower. Of all of the investments needed, only mining equipment and the underground mine should be included, and amortization and depreciation should not he included in the study.

Jan 1, 1998

By H. Suharyono, R. Hogg

A laboratory investigation was performed on flocculation following the addition of polymer to slurries flowing through pipes and in-line (static) mixers. Results are presented showing the effects of flow velocity, pipe length, in-line mixer elements and the use of multiple addition points. Flocculation performance was measured by the settling rate and the supernatant turbidity. The effects of agitation and mixing time are shown to be generally consistent with the results of equivalent tests (both batch and continuous) conducted in stirred tanks.

Jan 1, 1997

By Thomas S. Kovach

In today's competitive energy market, every effort must be made to assure the lowest possible production cost. 'rhi s. paper describes the cooperative effort between the coal producer and the utility customer to develop and install a fully integrated mine information management system at a 2.5 million tpy lignite mine in east Texas. A description of each item of the modules is included along with the problems encountered during development and how they were corrected. The system configuration is also described.

Jan 1, 1989

By D. Nilsson

This paper demonstrates the importance of including a discount rate in the determination of the optimum final' depth of an open pit. Without a proper discount rate, a pit will probably end up too deep. Another consideration is future underground mining. If underground mining is profitable, the pit may need to be shallower. Of all of the investments needed, only mining equipment and the underground mine should be included, and amortization and depreciation should not he included in the study.

Jan 1, 1997

By Conrad Parrish

As originally conceived, this paper was to address the costs of environmental compliance, focus on environmental impact statements, and describe how those costs impact mining projects. The intent was to do wide ranging mathematical analyses to demonstrate the varying impacts on mining projects depending on their size, timing, return on investment and other salient project features. The initial portion of the numerical analysis necessary to this purpose was performed. The results showed a pattern of impacts familiar to the mining industry:

Jan 1, 1991

By A. M. Taweel, M. T. Ityokumbul, A. I. A. Salama, M. W. Mikhail

The liquid-phase mixing within CANMET's Western Research Centre's (WRC) 0.76-m-diem pilot-plant flotation column was characterized using a salt tracer. The process variables studied were frother addition and, gas and liquid flow rates. The response of the column to a tracer pulse was monitored at three axial and two radial locations. The results showed that the 2-tph flotation column was well mixed. Discussed are the implications of this observation to column design and scale-up.

Jan 1, 1996

By S. R. Clifford

Organic contaminants can be removed from river sediment using conventional flotation methods. Organic contamination in sediments is one of the most significant pollution problems facing the Great Lakes region. Using conventional flotation, the majority of the organic contamination can be collected in a concentrate, leaving a "clean" tailings. This provides a cost savings by reducing the amount of material requiring further treatment. The concentrate can then undergo additional flotation stages, or other contamination removal procedures, to further remove the organic contaminants.

Jan 1, 1994

By W. V. Harper

The travel path of a freed radioactive particle in an aquifer must be estimated from a limited number of available samples. This paper discusses geostatistical methods that minimize the 'uncertainty' associated with the predicted hydrologic surfaces and the predicted travel path. However, any estimation method will produce a single smooth predicted path. This 'sensitivity' will he evaluated using a geostatistical simulation method. The techniques will be illustrated using published data from the Wolfcamp and Pennsylvanian aquifers in the northern Texas Panhandle.

Jan 1, 1990