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By John C. Heter

The P.W. Gillibrand Company holds 705 placer and lode claims in the Precambrian San Gabriel Anorthosite Complex of the western San Gabriel Mountains. These claims contain large tonnages of ilmenite, magnetite and apatite with anomalous quantities of zirconium (zircon), niobium, vanadium and rare earth elements. Stockpiling of heavy mineral concentrates associated with aggregate mining from alluvial pits has occurred since 1984. The limited reserves of material from these alluvial deposits and their relatively low heavy mineral grades caused Gillibrand Company to initiate an extensive drilling and exploration program to develop the hardrock resources of ilmenite, apatite and magnetite.

Jan 1, 1995

By Tomb. T. F., R. A. Haney

During the past several years, the Mine Safety and Health Administration (MSHA) has conducted studies in underground mining operations to obtain information on occupational exposures to diesel particulate (DP), mine environmental DP levels and on the effectiveness of methodologies used to control DP. The studies conducted were representative of four coal mines and 10 metal mines. The metal mines included two lead-zinc mines, one limestone mine, two potash mines, one zinc mine and four salt mines. Three of the four coal mines were using disposable diesel exhaust filters to remove particulate from the exhaust and one was using a reusable wire mesh filter. Results of these studies indicate that average DP levels in coal mines not using exhaust filters range from 0.9 to 2.1 mg/m3, The use of exhaust filtration devices reduced these levels by about 50% to 90%. Studies conducted in metal and nonmetal mines showed average DP levels ranging from 0.3 to 1.6 mg/m3.

Jan 1, 1996

By Malcolm J. McPherson, Satya Harpalani

A thorough knowledge of coal permeability and its variation with factors like stress conditions, and time, is useful in simulation studies of mine ventilation and coalbed methane recovery, as well as characterizing coalbed methane reservoirs. An experimental investigation was carried out to study the gas flow characteristics of coal to enhance the under- standing of the mechanism of methane flow through it. The work consisted of measurement of permeability of coal samples under triaxial stress and an examination of the physical structure of coal using electron microscopy. Effort was made to fit the experimental data to several phenomenological models that have been used to describe fluid flow through porous media. It was realized that gas flow through coal cannot be described by models that assume this flow to be through a bundle of capillary tubes. However, results suggest that this gas flow could be predominantly through fractures and cracks in coal, and this could be represented by flow between parallel plates.

Jan 1, 1986

By Jorma Miettunen

The Plant. The annual production of the Pyhasalmi mine is 900 000 tons of copper- zinc-pyrite ore containing approximately 0.7 % Cu, 2.5 % Zn and 30 % S. During 1976...1981 altered surface ore, 850 000 tons in all, was also treated at the concentrator. The surface ore was crushed and ground in a separate plant and was then fed into the copper or zinc flotation or was flotated in its own circuit, depending on the degree of alteration and the content of copper and zinc in the ore. The surface ore was exhausted in October 1981. Flotation comprises three consecutive flotation circuits; copper, zinc and pyrite circuit. The zinc circuit includes an open circuit roughing and scavenging. The scavenger concentrate and cleaner tailing are pumped to the middlings flotation. Rougher concentrates of the open circuit and the middlings flotation are pumped to cleaning which includes four stages. Figure 1 describes the flowsheet of the zinc circuit.

Jan 1, 1982

By William A. Dupree, Mark J. Schultz, William J. Francart

Maintaining intake escapeways clear of contaminants from mine fires has been an issue for many years. Removing fire sources from these entries reduces the risk of contamination greatly. In recent years, concerns have been raised related to contamination of the intake escapeways by leakage when fires occur in adjacent airways. This paper discusses measured leakage rates for multiple stoppings at various pressure drops across stopping lines in a number of actual coal mines. Also addressed are methods for reducing the contamination risks for the intake escapeways, considering the ventilation system employed. The Effects of Air Leakage The effects of air leakage through ventilation controls has been well documented. While normal leakage is expected through stoppings, overcasts and other structures, abnormally high leakage results in an inefficient ventilation system and can increase operational costs for a mine. In addition, excessive leakage results in less control over mine ventilation airsplits. This may compromise the isolation of mine escapeways, and allow adjacent entries to be rapidly contaminated by products of combustion in the event of a mine fire. A study was conducted at ten mines in which air pressure and quantity measurements were taken near the active sections. The method used to construct the ventilation controls to separate airways was also noted. Stopping Construction Table 1 shows the type of stopping construction commonly used in the 10 mines included in this study. Main entry stoppings were normally built with mortared joints (wet stacked) with sealant applied to the high pressure side of the stopping. In most cases the entire face of the stoppings were sealed. In one case only the joints between blocks were sealed but the perimeters were sealed in all cases. Some mines also sealed the low pressure side of the stopping. Solid blocks were normally used for main entry construction and hollow blocks were sometimes used for longwall panel development. [ ]

Jan 1, 1993

By Steven A. Bradbury

INTRODUCTION Passive dust control systems are quickly gaining acceptance in the bulk solids handling industries. The number of applications is increasing due to proven performance, especially in US power plants burning Powder River Basin coal. Air Control Sciences ®, Inc., of Boulder, Colorado, has over forty (40) patented Dustless Transfer ® systems in operation. All of the installations control workspace dust levels to less than 2.0 mg/m3, and in some applications reduced conveyor dusting by over ninety-eight percent (98%). Passive systems control fugitive dust emissions by minimizing the induced airflow in bulk material transfer and slowing its velocity. Traditionally, fugitive dust control in the mining industry was accomplished using either dust collection systems or dust suppression systems. The term passive dust control, indicates these methods don't use any active dust collection or suppression. Passive dust control systems are best suited to transfer from one conveyor to another. They can also be applied to transfers from feeder to conveyors.

Jan 1, 2004

By D. W. Tedder

Several bauxite feeds and residue sands and muds, produced by Bayer plants in the US and over-seas, were fractionated using dry and wet magnetic separators. The magnetic sand fractions typically contained about 50 to 60 wt % Fe2O3 and the bulk of the radioactivity in the sands. The muds are more difficult to process, but some fractionation is possible using a combination of classification and magnetic separation techniques. Among the mud samples, higher radiation levels are often associated with the less magnetic fractions. Bauxite is more easily fractionated using dry magnetic separation. Much of the radioactivity in bauxite appears to concentrate in the sand and mud residuals.

Jan 1, 1987

By M. Christou

The LIFE-Environment Demonstration Project ?Treating Waste for Restoring Land Sustainability?(www.bangor.ac.uk/ies/TWIRLS/TWIRLS_home.htm), a project initiated by the University of Wales, Bangor, UK in which NAGREF is a partner, aims to demonstrate the effective use of industrial and municipal wastes for the remediation of post-industrial and degraded sites in urban and rural sites. Within the framework of this project, a schist quarry, which is located in a mountainous area near Athens and which has been exploited in the past for cement production, was chosen for bioremediation experiments in collaboration with the quarry owners, TITAN Cement Co. Three different areas within the quarry were selected representing 3 different topographies. These were a compacted, flat area with seasonal water logging (untreated control), a gently sloping, land formed area; and artificially created mounds of overburden rock material formed on the flat area. Compost produced from mixing municipal waste, green waste and digested sewage sludge at the recycling plant of the Association of Communities and Municipalities in the Attica Region (ACMAR), near Athens was used for nutrient amendment. Six replicates of three treatments were applied with varying compost application rates in order to examine the effect of the addition of organic matter in the establishment of suitable vegetation on the infertile schist material. Pine trees (Pinus halepensis Mill.), 4 per replicate, were pocket planted in a volume of 3 liters of schist or schist-compost mixture (1:2 and 2:1). Tree height, main stem diameter and branching were measured following planting and these measurements will be repeated annually to test hypotheses that compaction and water logging reduce Pine establishment by natural regeneration and that nutrient addition improves establishment of pine on schist waste. The availability of nutrients and variation in other soil physico-chemical parameters will also be studied in each treatment and related to plant growth. As a demonstration project, open days are planned on the site for the public and official bodies involved in municipal waste handling and other relevant areas. The aim of these will be to illustrate the effective re-use of waste for the sustainable restoration of post-industrial and degraded land.

Jan 1, 2006

By Osvaldo Bascur, Laurent Garrigues, Nouna Kettaneh, Svante Wold

The chemical, oil, semiconductor, mining, and paper and pulp industries, as well as most other modern industries, are rapidly expanding the range of measurements used to characterize raw materials, process steps, intermediates, and final products. In addition, process variables such as temperature, pressure, and flow become more and more numerous, providing extra information on the state of the process. However, no matter how many sensors are added, the underlying sources of variations that drive the process behavior remain constant. On the other hand, the measuring frequency of these data has increased from once a day or once an hour to once, ten, or even hundred times a minute. This gives masses of data that are swelling in both directions (more variables and more observations). These data need to be properly stored, managed, and analyzed to provide diagnostics about the state of the process as well as an understanding of the relationships between different parts of the process and the product properties. Projection methods such as PCA (principal components analysis) and PLS (projection to latent structures) compress process data to informative summaries of the original variables. These can be shown on line, providing an efficient, graphically oriented suite of diagnostics regarding the "health" and performance of the process. The power of these methods is illustrated by two examples of industrial data in the mining industry.

Jan 1, 2000

By N. J. Themelis

It is a pleasure to introduce this session on frontier technology and present an overview of pyrometallurgical technology, as it is today and where it may be heading. While there have been many advances in hydro-metallurgical processing in our times, pyrometallurgy has not been still, and more novel processes have been introduced in the last four decades than in all previous ages of humanity put together. As a result, pyrometallurgy has managed to remain the predominant mode of producing metals from ores and concentrates: over 95% of the world primary metals production, including iron, manganese, copper, lead, chromium and nickel, is obtained via the high temperature route. Some of the characteristics of pyrometallurgy, along with the corollary industrial advantages are shown in [Table 1]: [ ] On the other hand, the necessity of operating at high temperatures also entails special problems and it is unfortunate that research on how to overcome these problems has not, in most cases, kept up with the development of these wonderful novel processes. We shall first speak of the important developments in pyrometallurgy which have brought us to the current state of the technology, and subsequently on the problems still encountered and the kind of research and development that will be necessary to bring pyrometallurgy on a par with other late twentieth-century technological developments.

Jan 1, 1985

By L. Piga, G. Belardi, V. Alesse, N. Shehu, J. Freund

The physico-chemical interactions among minerals such as olivine, chromite and serpentine; the most commonly present ions in solution such as Ca and Mg; and flotation reagents such as EDTA and oleic acid were investigated. The study was conducted via release tests, electrophoretic measurements and microflotation of selected minerals coming from the Kukes deposit in Albania. The results were confirmed in beneficiation tests on two ores, one from the Kukes (Kalimash) deposit and the other from the Rizo deposit in Greece. It was demonstrated that, when Na-oleate is used as collector, chromite, olivine and serpentine can be separated at pH 2.5 and/or pH 5.5 when employing ethylenediamine tetraacetate (EDTA) on previously deslimed material. This approach ensures flotation concentrates with a Cr203 content better than 50% with a recovery of more than 75%.

Jan 1, 1998

By S. A. Pierce

Heightened environmental consciousness has resulted in the development of various international accords dealing with natural resource management. This international awareness is now being translated into regional and local initiatives that proactively implement collaborative environmental management programs. One such program was recently initiated in northern Chile in recognition of the interconnection of Andean salars. Cooperative efforts between industry, governmental agencies and academic professionals have resulted in the implementation of simultaneous environmental monitoring of flora and fauna in the salars of northern Chile. This coordinated effort is leading to an improved understanding of the migratory patterns of South American fauna, as well as improved access to an expanded database for the multiple user groups associated with the Andean salars. The El Abra Mine is actively participating in these coordinated monitoring efforts.

Jan 1, 1999

By J. F. Stenebråten, W. P. Johnson, D. R. Brosnahan

Carbonaceous materials (CM) from ores of varying preg¬robbing activity from Barrick Goldstrike Mines Inc. (BGMI), Nevada, were characterized in terms of their functional group contents, hydrocarbon contents, elemental composi¬tions and humic acid contents. Fourier transform infrared (FT-IR) analyses did not show the presence of hydrocarbons or carboxylic, phenolic or sulfhydrolfunctionalities. The FT¬IR bands present included C=C stretching in aromatic rings and C-O-C stretching, indicating the presence of oxygen as ether linkages or thiocarbonyl functionality in the carbon matrix. Calculated atomic oxygen to carbon (O/C) ratios did not reveal a trend between the maturity of the CM and the preg-robbing behavior, possibly due to the low resolution inherent in electron microprobe analyses. However, the atomic O/C ratios agree with other chemical analyses, indi¬cating that the organic carbon is very mature, similar to or higher than anthracite grade coal. Gas chromatography¬mass spectrometry and nuclear magnetic resonance analy¬ses corroborated the relatively featureless character of the carbon, indicating that the carbon structure is virtually completely aromatic (graphitic).

Jan 1, 2000

By P-M. Dupond, S. Lowrie, C. Tauziéde, Z. Pokryszka, A. D. Jones

A physical model has been developed to simulate the flows and mixing of gases in the waste of a longwall retreat coalface. The model is used in conjunction with computational modelling, and the distributions of permeability and gas emission in the model waste follow those in computer simulations (Pokryszka et al 1996). The physical model represents at 1170th scale a 200 m long, 3 m high coalface with a waste extending up to 280 m to the face start line. The model is tilted to the same seam slopes as the real face, e.g. 22° ascensional ventilation along the face and 7" slope to the dip. The purpose is to investigate the flow of three components: ventilation seepage flow through the waste; methane; and nitrogen injected to quell spontaneous combustion. A heavier-than-air surrogate gas (SF,) is used in place of methane, and therefore the model is inverted so that gas layers form along the 'roof". The main forces driving the flows in the waste (pressure gradients due to ventilation and the density difference of gas layers) are kept in proportion by appropriate scaling of the permeability. Calibration and validation used data from a coalface at a mine in the Lorraine coalfield. The model is now in operational use.

Jan 1, 1997

By E. F. ‘Pat’ Nelson, Richard Broom

Our portion of this afternoon’s session is dedicated to the operation of automatic process control associated with small to medium size primary or SAG milling circuits. In recognition of the subject matter of this symposium, specifically precious metals, our historical reference is Rosario Dominicanna in the Dominican Republic, one of the largest gold producers in the Western Hemisphere. Plus a backward glance to review very briefly the initial performance of the big primary mills at Island Copper in British Columbia and Pima IV in Arizona. We will then get to the subject at hand with a discussion of a retrofit control logic recently installed on a 5000 hp primary mill. The focus of this review is the simple, inexpensive, and cost effective character of this retrofit installation.

Jan 1, 1984

By Lijun Xu, Jan M. Mutmansky

The purpose of this research was to investigate airborne coal mine dust characteristics in order to assess the possibility of contribution of these characteristics to the incidence of coal workers' pneumoconiosis (CWP). The characteristics studied included physical (mass concentration and size distribution), chemical (elemental composition), and mineralogical (quartz and kaolinite content) variables of the dust. The results are based primarily upon analysis of the characteristics of 99 impactor samples from 18 mines in seven states. Because the eight stages of the impactor span the range of dust sizes up to 20 microns, the characteristics analyzed should represent respirable dust characteristics well and also provide size-dependent representations of the characteristics. In general, the patterns of mass concentration and size distribution in the various mines studied were similar with mass concentrations being high downwind of the continuous miner. The concentrations and size distributions were more variable upwind of the continuous miner, apparently as a result of the variations in the dust conditions in the working section. Significant size effects on the elemental and mineralogical content are shown in the data. Concentrations of most of the elements decrease as size decreases. However, minerals content increases as the dust size decreases. Regional variations of elemental and mineralogical content are also significant. Quartz and kaolinite contents are small in regions with low incidences of CWP. However, the elements of Cu and Zn are high by comparison to their content in high-incidence coal fields and may have the effect of protecting against the disease.

Jan 1, 1991

An atomic force microscopy (AFM) has been applied to study the adsorption of potassium amyl xanthate (PAX) and potassium ethyl xanthate (KEX) on arsenopyrite surface in solutions. AFM images show that the collectors adsorb on arsenopyrite surface in patches at pH 6. Increasing the chemical dosage will increase the adsorption density of the patches on mineral surface. The increased probe-arsenopyrite adhesion measured in PAX solutions at pH 6 is attributed to the adsorption of the patches, suggesting the hydrophobic nature of the patches, which is likely the oily dixanthogen. It is also found that arsenopyrite is reactive in water in the presence of air. At a high pH with the addition of Ca(OH)2 the adsorption of collectors on arsenopyrite is greatly retarded or depressed because the mineral surface is coated by a lot of precipitates, which is hydrophilic in nature as shown by the measured strong repulsive probe-arsenopyrite detachment force. The findings confirm that the flotation behavior of arsenopyrite in xanthate solutions is very similar to that of pyrite.

Feb 27, 2013

By Lawrence W. Teufel

Knowledge of in situ stress and natural fracture distribution at depth improves our ability to stimulate and produce low permeability reservoirs. The focus of this study is three closely spaced, 2.5 km deep vertical wells in the Piceance Basin of Colorado. The wells were completed through the tight lenticular and blanket gas sands of the Mesaverde Group. In situ stress directions and magnitudes were determined from hydraulic fracture tests and anelastic strain recovery measurements of oriented core. The distribution, orientation, and characteristics of natural fractures in the subsurface were determined from detailed observations of over 1300 m of core, of which 400 m was oriented. Stress measurements clearly show that horizontal stresses are strongly influenced by lithology. In a sandstone/shale sequence at a depth of about 2.0 km in situ stresses in sandstone formations are anisotropic, with the average ratios of the minimum and maximum horizontal stresses to the overburden stress being 0.82 and 0.96, respectively. In sharp contrast bounding shale formations are lithostatic. This stress contrast between sandstones and bounding shale formations could act as a barrier to hydraulic fracture propagation during stimulation and impede vertical fracture growth. Natural calcite-filled fractures are present in over 7 percent of the core, with several horizons having a much higher frequency of fractures. Fractures are found primarily in sandstone. The fractures have a strong preferred orientation of N 1060E[+]110, which is aligned with the maximum horizontal stress and direction of hydraulic fracture propagation. The interaction between a well developed fracture fabric and anisotropic stresses in sandstone formations produces a permeability anisotropy, with the maximum permeability aligned with the fracture fabric and maximum horizontal stress.

Jan 1, 1986

By James E. Monsees

Extensive underground excavation will be required for construction of a mined geologic repository for nuclear waste. Hundreds of thousands of feet of drift will be required based on the conceptual layout design for each candidate nuclear waste repository. Comparison of boring and blasting excavation methods are discussed, as are special design and construction requirements (e.g., quality assurance procedures and performance assessment) for the nuclear waste repository. Comparisons are made between boring and blasting construction methods for the repository designs proposed for salt, volcanic tuff, and basalt. Differences in the geologic media and settings of the prospective sites influence the excavation method in terms of drift length, size of opening, drift slope, rock quality, and boreability. Support requirements, ventilation, and the ability of the geologic system to retard radionuclide migration are also directly impacted by the geology and excavation method.

Jan 1, 1987

By D. M. Avant, A. J. Solomon, S. M. Pickering, W. R. Fox

Introduction Most high purity silica is produced from crystalline quartz, generally from sand. However, there is a small area of southern Illinois where a porous, friable white chert rock is found that is very different in physical form from quartz sand. This microcrystalline material, commonly referred to as tripoli, is more easily ground to micron sizes than sand. Although of similar Moh's hardness, microcrystalline tripoli is less abrasive than either ground quartz sand or many synthetic abrasives. Location The southwestern corner of Illinois is underlain by extensive deposits of very porous chert; in some places the material is quite white. Two companies, Illinois Minerals Co. and Tammsco Inc., mine and process this white material. The Illinois Minerals plant is located at Elco, and the Tammsco plant is in Tamms, IL. Both companies mine from various locations within a 10-mile truck haul of their plants. Production from this district has been continuous since at least 1915. Malvern Minerals Co. mines and processes a generally similar microcrystalline, friable novaculite near Hot Springs, AR. Geology The southern Illinois white tripoli area is on the southern flank of the Illinois Basin. The commercial silica zone is a facies of the Clear Creek chert of Lower Devonian Age. To the north, where it occurs deep in the basin, the Clear Creek is a siliceous limestone. In the mining area, thin overburden has allowed access by surface ground water, which has leached away the carbonate content and left a quite pure silica residue. Fossils characteristic of sea bottom deposition, such as brachiopods and trilobites, are occasionally encountered in mining. The structure of the mining area is poorly known, due to infrequent outcrops. Strata in most mines are inclined at dips of 5° to 20°. There appear to be occasional high angle normal and reverse faults, but these are seldom of any significance in mining. The friable white silica zone mined in the Clear Creek chert is overlain by dark brownish-red chert and siliceous shale. Exploration drilling to date has not encountered the base of the microcrystalline tripolitic zone. Chemical content Leaching by ground water solution has removed virtually all the carbonate from the original siliceous limestone. Impurities encountered are red to yellow iron oxides, aluminous clays, and occasional black manganese oxides. The silica has no detectable formula water. A typical chemical analysis and physical properties are listed in Tables 1 and 2. Mineralogy and crystallinity Southern Illinois friable tripoli appears amorphous under the polarizing microscope. No crystal structure and only occasional, vague, patchy anisotropism is evident. However, the material gives an excellent quartz X-ray diffraction pattern. Thus, so far as X-ray mineralogy is concerned, the material is clearly

Jan 1, 1987