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By J. M. Pachter

Property sales and acquisition are prominent features of today's coal industry. Before selling or buying a site, a company must know the property's economic net worth. Any evaluation of economic net worth would be inadequate if determinations of a property's environmental liabilities and costs were omitted. Short-and long-term costs can result from liabilities related to reclamation, water treatment, subsidence, and hazardous waste disposal. A structured, interdisciplinary approach can aid in the delineation, summation, and scheduling of these costs and liabilities.

Jan 1, 1987

By Lawrence A. Ph. D. Hansen, J. David Deatherage

Laboratory testing programs were conducted to investigate the performance under compression loading of several types of geomembranes and geotextiles proposed for use in heap and dump leach projects. Synthetic liners of several thicknesses were sandwiched between representative subgrade soils and cover materials, thus modeling in the laboratory the actual installation conditions expected. Performance was evaluated by visual inspection and vacuum testing. Several testing procedures and equipment were used to investigate the effect of these testing parameters on the predicted performance.

Jan 1, 1987

By Rashi Tiwari, George Danko, Jeremy Knowles

A control technique is described for enhancing the efficiency of materials handling and other mining operations. The concept involves human-operator and robotics control interactions to assist in mining operations. Many mining tasks require a human operator to coordinate the motion of several machine links by simultaneously manipulating multiple joysticks or other control devices. The new control architecture allows for automatic coordination of multiple machine joints. The machine movement may follow a computer-optimized, learned coordination pattern, while the operator still retains the master control of the overall trajectory and velocity parameters. Examples are described for a surface mining front shovel.

Jan 1, 2005

By R. K. Mehta

Conventional triboelectrification based dry coal beneficiation methods require ground coal as a prerequisite feed material, energy intensive static-in-line mixer or cyclonic tribocharger configuration, and transport and/or improvement in the design of free-fall separators to improve the separation efficiency of [me pyrite/mineral matter from coal. The proposed paper illustrates the two concepts. First, the use of ceramic media in a polyurethane lined attitor in achieving simultaneous grinding and differential charging. Second, the use of an electrocentrifuge to selectively separate coal from mineral matter present in the triboelectrified mixture. It is of interest to note that some ceramic media can satisfy the requirements of both desired density and work function to achieve grinding and differential charging.

Jan 1, 1996

By R. L. Lewis

The White Pine Mine is a large underground copper mine located in the Upper Peninsula of Michigan. A numerical ground water flow model of the White Pine Mine was constructed to evaluate potential engineering controls that would reduce the rate of mine-water discharge after closure. Of the passive controls evaluated, the placement of bulkheads within the mine workings was predicted to offer the greatest benefit, reducing the rate of discharge by as much as 35%.

Jan 1, 1997

By Frank F. Aplan

Coal flotation offers the promise of a highly effective, large tonnage, low cost means of cleaning fine coal. Unfortunately, it has, to date, not lived up to its promise. Several problems that need to be addressed before coal flotation can achieve its promise are discussed and possible solutions offered.

Jan 1, 1989

By Robert C. Bates

Background is given on the various equations used to describe diffusion and convective flow of radon in porous media. Bureau-developed equations for modeling diffusion and Darcy flow through multilayered porous media are described briefly, and examples of their use are given. Analysis results discussed include: The transient effect of pressure changes in different length models, time dependent flux changes in multi-layered models, and radon flux through pinholes in sealants

Jan 1, 1980

By T. Brady, J. Johnson, J. Whyatt, B. Pariseau, M. Stahl

An elastic-viscoplastic material model allows for time- dependent rock mass motion in proportion to excess stress above the elastic limit. The model produces rounded stair-step curves of displacement vs. time that are similar to those obtained from recent borehole extensometer measurements made in the central portion of the Ross Shaft pillar at the Homestake mine. The work in progress, including two- and three-dimensional finite element analyses using the UTAH2/3 codes, indicates that the model is a step towards more realistic safety and stability analysis, but that inclusion of rock mass damage may be desirable.

Jan 1, 2000

By J. B. Nanor, J. Lorengo, M. Misra, C. B. Bucknam

The dissolution of mercury during the gold cyanidation process is the cause of many environmental, health and processing problems. The removal of mercury-cyanide complexes from synthetic solutions and process water were investigated using sodium and potassium dimethyl dithiocarhamates and sodium sulfide as precipitating reagents. The results have shown that efficient mercury removal can he achieved by the formation of stable mercury compounds with the addition of potassium dimethyl dithioearhamate. The mercury dimethyl dithioearhamate precipitates are stable under plant operating conditions, and they do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is possible to stabilize mercury in the heap during cyanidation by adding dimethyl dithioearhomate.

Jan 1, 1999

By Carl P. Maronde, William P. Barnett, Patricia A. Rawls

The commercial deployment of advanced fine-coal cleaning technologies depends on cost-effective approaches for efficient separation and ancillary operations in handling, dewatering, drying, and transporting coal fines. As a result of two solicitations under the High-Efficiency Preparation component of the Department of Energy Coal Preparation Program, several projects were initiated for testing and evaluation of emerging technologies and equipment that address operational difficulties associated with coal fines. This paper will update the status of those projects and discuss how the technologies they represent can ameliorate some problems associated with coal fines in today's preparation plants.

Jan 1, 1995

By Richard K. Thorpe, Francois E. Heuze

The concept of a reusable underground nuclear test facility, named HEDEF, has been under study for some time. This rock chamber would have to be engineered to sustain the repeated mechanical and thermal shocks of internal explosions. In this paper, we summarize preconceptual studies performed in support of HEDEF, including -simple dynamic calculations for internally loaded tunnels, -outline of proof-of-concept tests of proposed reinforcement, - and initial dynamic testing of reinforcement components in an underground high explosive (HE) test.

Jan 1, 1986

By Alexander B. Ikonnikov

All known bauxite deposits in China occur in its eastern half, and almost all of them are found in the Carboniferous and the Permian. They are of platform origin, but contain diaspore as the major ore mineral. There is only one known deposit composed of gibbsite. The most valuable deposits are sedimentary ones formed in local depressions on the edges of platforms during marine transgressions. They lie on Upper Cambrian or Middle Ordovician limestone that was weathered for a long period of geological time. Generally, Chinese bauxites are low in iron, and have a rather low alumina/silica ratio.

Jan 1, 1984

By M. Manrique, E. E. Vidal, I. Accorsi, P. R. Taylor

Various pyrometallurgical methods for treating ilmenite and zircon concentrates are reviewed. Laboratory experiments using a thermal plasma reactor were performed to evaluate the conversions of ilmenite to TiC or TiC-Fe and zircon to ZrC or ZrC-SiC. Results are examined and possible processing routes are identified.

Jan 1, 1999

By W. G. Pariseau, S. C. Schmelter

The destabilizing effect of water pressure on rock-mass stability is examined quantitatively by the finite element method. A coupled code that accounts for the simultaneous effects of rock-mass deformation and transient fluid flow is used for this purpose. The traditional soil-mechanics assumption of an incompressible fluid is shown to be untenable for the analysis of porous, fractured rock slopes. A Mandel-Cryer effect, whish is a transitory but elevated and potentially destabilizing water pressure following a cut, was not observed.

Jan 1, 1999

By S. B. Castor

Although production generally satisfies demand for rare earths, new markets may make undeveloped resources, particularly those rich in yttrium, more interesting. A Precambrian carbonalite orebody at Mountain Pass, California, has been the world's largest rare earth producer. Minor rare earth production comes from titanium placer mining in Florida and uranium mining in Canada. Prior to operations at Mountain Pass, North American production was mostly from placer deposits that constitute large, low-grade rare earth resources. Newly discovered North American rare metal resources in peralkaline igneous rocks are potential yttrium producers. Most of these resources are in a continent-wide belt of anorogenic magmatic rocks approximately coeval with mineralization at Mountain Pass. Other untapped rare each resources in North America are generally light rare earth-dominated and small or of low grade.

Jan 1, 1991

By V. K. Karra

Research by various workers has shown compressive comminution to be significantly more efficient than impact comminution. Based on the work being done at Nordberg, wet compressive crushing in cone crushers producing finer and finer products, shows the feasibility for partial substitution of conventional tumbling mills. For further substitution, major challenges are processing of fine feed slurries in cone crushers to realize a significant size reduction of the particles, and understanding the limitation of the gyratory type units in terms of finest product achievable. The paper addresses the challenges involved, efforts at Nordberg, and the implications to conventional comminution flowsheets.

Jan 1, 1989

By K. E. Kolm, W. H. Langer

Developing natural aggregate resources (sand, gravel and stone) creates environmental impacts. A systems analysis method was designed to characterize the components of the environmental system, identify potential impacts to those systems and evaluate the extent of those impacts. The stepwise method consists of problem definition, data collection, preliminary conceptualization and characterization, additional data collection, data analysis and refinement. The method requires analyzes of various systems making up the environment, including land surface, geomorphic, subsurface and groundwater systems. After system characterization is complete, the method focuses on identifying and evaluating potential environmental impacts to determine acceptable mining strategies.

Jan 1, 2003

By Andrew Neale, Ari Supomo, Mike Mular, Rob Perry

A method is presented to measure and correct the performance of regulatory control loops. Freeport Indonesia treats over 220,000 dmtpd of copper-gold ore in a complex of four concentrators. More than 400 regulatory control loops are implemented throughout the operation. The performance of each loop is quantified by an index based on its time in automatic, the deviation of the measurement from the setpoint and a metallurgical assessment of its impact on overall plant operation. Index values are recorded in a plant-wide data acquisition system and analyzed to produce a report of loops requiring attention. Loop statistics are analyzed to show if the problems can be corrected with tuning. The practical application, benefits, management and staffing requirements of this method are discussed.

Jan 1, 2000

By Richard L. Ranich, Frank F. Aplan, J. B. Hiskey, Robert S. Thompson, B. J. Scheiner

Acidic waters typified by acid mine drainage, copper dump leach solutions and steel pickle liquors will typically contain SO4-2 and cations such as Fe+3, AI+3 and for the pickle liquors, sometimes Cr+3. These acidic waters will often react with limestone, present naturally or introduced for purposes of solution neutralization, to form reaction - inhibiting coatings of gypsum and gelatinous, metal hydroxide precipi¬tates. The coating thickness, as a function of pH, was quantified for both reactive (calcite, limestone) and non-reactive (quartz, barite, fluorite) minerals, and the data were related to the hydroxy species diagrams and to solution turbidity measurements. Coatings were found on the reactive minerals at a lower bulk solution pH than on the non-reactive minerals.

Jan 1, 1993

By D. E. Ranta, Neil D. O’Donnell, Thad B. Ostrowski

Ore reserve estimation at the Syncrude Canada Ltd. open-pit oil sands mine in Northern Alberta has evolved since the project's inception. Early techniques followed a conventional petroleum reservoir analysis format, with relatively widely spaced drill holes and semiquantitative grade data. Experience has developed a more standard mining approach, including classification of geological materials by both lithology and sedimentary origin, timely and multi-purpose drill holes, precise analytical data, empirical recovery factors, a computerized geological data base, and an orebody block model. Future efforts will involve enhancement of existing techniques, use of geostatistical algorithms, quantification of confidence limits, and improved control of the ore model by geological parameters.

Jan 1, 1992