Search Documents

By R. L. Grayson

Conventional mine safety wisdom states that "the most efficient mines are also the safest." Since the 1980s, small mines (and contractors) have been targeted as the most dangerous because of their fatality records. However, statistical analysis of West Virginia safety and production data from 1993 indicated that, when considering the correlation between accident severity and tons mined per employee-hour worked, the most efficient mines were, with the exception of very small mines, not the safest operations. This paper presents the results of an extended analysis of West Virginia mine safety using 1993 and 1996 data and concludes with the method used to suggest current priorities for focusing interventions.

Jan 1, 2000

By B. Karatzoglou

The penetration of sustainability principles in business practices has introduced the necessity for a simultaneous integrated assessment of the corporate economic, environmental and social performances. Continuous technological, political and legal evolutions indicate that Sustainable Development (SD) principles will soon have to be implemented in all sectors of the Greek corporate reality, among them in the Mineral and Mining Industry. However, the ultimate criteria for the evaluation of a company?s performance remain its profitability and its market value. Managers, shareholders, financial intermediaries, all alike, emphasize and base their decisions on the various accounting produced ratios of return (ROA, ROE, ROCE, Residual Value) included, or produced by data found, in the financial statements of the companies. This paper offers evidence that the traditional accounting ratios discourage the implementation of investment plans that aim at improving the environmental performance of companies and therefore can be inadequate and misguiding for SD applications. International studies have consistently traced a positive relationship between the environmental performances of firms and their financial positions. Yet, the fact that investors tend to reward proactive companies by increasing their corporate values is disregarded by the return ratios, which usually set up the basis for management rewards and bonuses. The book value of the firm assets and owners? equity from which such ratios are produced diverges strongly from the real corporate value, defined as the traded amount for the stock of a firm. There is an urgent need for an adjustment of the return ratios so that they can record the positive economic impact of a more sustainable attitude and encourage decision makers towards this direction.

Jan 1, 2003

By Eric Forssberg, Ming-wei Gao

Four parameters of the Drais stirred ball mitt, i.e., bead load, bead size, flow rate and top feed size have been studied regarding their influence on the specific surface area. A factorially designed scheme was employed for conducting 27 mitting tests. The results show that the bead toad is the most important parameter in terms of increasing the specific surface area with less energy consumption. The bead size is also important. The optimum ratio of bead size to top feed size is found to be 14 to 80, which is much wider than in bat2 milling. The variations in flow rate and top feed size appear to influence the process insignificantly.

Jan 1, 1992

By D. S. Kostick

Soda ash production in the United States during 1994 increased 4%, reaching 9.3 Mt (10.2 million st). That was the second highest production year. Domestic nameplate soda ash capacity is about 11 Mt (12 million st). Overall, the industry operated at about 85% of capacity. Some companies produced at 100% of capacity while others produced at below their design ratings. Although domestic soda ash consumption was slow during the first half of the year, third- and fourth-quarter sales increased, especially in the flat¬glass and fiberglass sectors. These two sectors increased because of greater demand for glass products in the automotive and construction industries. Soda ash sold for pulp caustic soda increased during 1994. This was due to higher prices for and reduced availability of electrolytic caustic soda. It is often preferred for pulp digestion because of its stronger alkalinity.

Jan 1, 1995

By J. E. Chilton

Methanometers with catalytic heat- of-combustion sensors used in coal mines today will read low for flammable gases when oxygen (0,) concentrations are low or when methane (CH,) concentrations are greater than 10%. Thus, these methanometers may not be reliable during operations such as fire fighting or recovery of sealed mines. The U.S. Bureau of Mines developed a total flammable gas detector (TFGD) to measure CH, at concentrations up to 100% and to measure flammable gases in low 0, concentrations. This paper describes the operation and construction of the TFGD and discusses measurements of flammable mine gases obtained from a mine in western Pennsylvania.

Jan 1, 1992

By R. P. Benson, D. H. MacDonald, D. R. McCreath

1 - INTRODUCTION The Canadian Shield is well known as being among the older exposed areas of the earth's surface. Except for local zones, its extent from the Arctic to central North America is characterized by strong and durable crystalline rocks. It is generally regarded as highly competent for tunnelling and underground excavation and, as a result, many openings are excavated in it with minimal temporary support. If hydraulic efficiency is not a factor, tunnels do not usually require continuous concrete linings. A high percentage of the crystalline rocks of the Shield are of metamorphic origin and as such one of the dominant characteristics is their foliation. Zones of sheared or faulted rock are common in the Canadian Shield, particularly in association with foliation. These zones may be created during the late stages of the metamorphic process, leaving shear zones as an integral feature of foliated rock. As foliation is a preferred direction of weakness, deformation and rupture during subsequent tectonism may also create parallel shear zones. These "foliation shear zones", as described by Deere (1973), are an adverse feature of the otherwise durable rocks of the Canadian Shield. The zones may range from faults of major proportions to seams only a fraction of an inch thick. If fault gouge or alteration products exist in the zone the strength of the rock mass may be great1y reduced. As foliation is usually continuous, large unstable wedges of rock may be created if the opening is subparallel to the foliation. The effect on the construction of underground openings in terms of excavations, support and scheduling can be significant.

Jan 1, 1974

By Eung Ha Cho, Olufemi Olajide

A laboratory study of dense-medium cycloning with Redstone seam coal has been conducted. The investigation was performed using a 203 mm (8 inch) Heyl-Patterson dense-medium cyclone. Two underflow orifices of 31.8 mm (1.25 inch) and 44.5 mm (1.75 inch) in diam were used. The effects of feed pressure and particle size were determined on the cycloning performance. In addition, the cyclone performances with coal-rich and refuse-rich samples were also investigated. The results of the experiments were analyzed using basic hydrodynamic principles. The increase in the feed pressure increases the specific gravity of separation (defined as the specific gravity of a particle which has an equal chance of reporting to either the overflow or underfow) for both underfow orifices. The specific gravity of separation increases as the particle size decreases with the smaller underflow orifice. However, an opposite relationship has been observed with the larger under flow orifice. The separation becomes sharper with the smaller under flow orifice than with the larger underflow orifice especially for fine material. Also, the separation becomes sharper with an increased feed pressure for a coal-rich sample. However, this effect is less significant for a refuse-rich sample. This means that a high feed pressure is required for a coal-rich sample to maintain a good separation. It also means that applying a high feed pressure provides a good separation regardless of the type of feed coal in terms of ash content in the solid.

Jan 1, 1990

By J. C. Judd, D. D. Harbuck, M. D. Odekirk

The US Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent, such as SO2 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage countercurrent leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with SO2 or sulfuric acid.

Jan 1, 1992

By H. Lyn Bourne

The is the 14th consecutive year for this column and the 13th in which the royalty data have been tabulated. Some holes still exist in the list of royalties that readers hopefully will fill. Construction aggregates - either sand and gravel or crushed stone - are the most common mineral commodity. In spite of their pervasive use nationwide, royalty information for these commodities has been difficult to acquire from some states. Readers can help. Share information about these missing states and next year there will be fewer states without information. Dennis Bryan sent a copy of a report, "Regional Appraisal of Mineral Materials: Carson City District, BLM." The report was authored by real-estate appraisers. It contains more than 50 references to leases of various construction materials in Nevada and nearby states. It gives a thumbnail sketch of each lease and is a good reference. However, the authors erroneously imply that the royalty rate and the in-place value are the same. Several of this year's new entries come from the report. However, the royalties for landscaping materials vary from state to state and by rock type. Some boulders used for landscaping in Nevada have a royalty reported at $1.10/t ($1/st). At the other extreme is lava from Idaho. Used for the same purpose, it has a royalty range of $11 to $18.70/t ($10 to $17/st). Chuanming Tian of Beijing, China has shared some information about the changing mineral royalty policies in China. China first implemented an oil and gas royalty in 1984. In 1992, the government expanded that to include iron ore. In 1994, the royalty policy was extended to all mineral commodities. At the same time, the royalty rate for iron ore increased tenfold.

Jan 1, 1995

By D. D. Harbuck

The US Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent, such as SO2 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage countercurrent leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with SO2 or sulfuric acid.

Jan 1, 1991

By N. L. Parduhn

Populations of Bacillus cereus spores are elevated in soils over four subsurface gold deposits in the western United States. Large deposit-to-background ratios of B. cereus populations were obtained in soil traverses over the Minnesota vein deposit, Empire District, Colorado (maximum 50:1); the Shasta (maximum 3,500:1), and Evening Star maximum 18,000:1) vein deposits, Shasta County, California; and the Hog Ranch disseminated gold deposit (maximum 40,000:1) in Washoe County, Nevada. Small increases in the concentration of toxic metals in the soil may be responsible for the elevated spore populations. The observed elevation of B. cereus spore populations near these gold deposits indicates that the method should be further investigated as a potential exploration tool.

Jan 1, 2013

Eldorado Resources Ltd.(ERL) uses a solvent extraction process for the processing of uranium ores. The solvent extraction plant consists of 4 extraction and 5 stripping stages with regeneration carried out as required (Wyper, 1982). Extraction is carried out with a solvent consisting of 4.5 vol % Alamine 336, 4.5 vol % Isodecanol and 91 vol % kerosene. The extraction step can be represented as In equation (1).

Jan 1, 1988

By Michael Fehler, Hidenshi Kaieda, Leigh House

Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and independent1 y confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional we1l 1ogging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we be1 ieve that the microearthquakes result from slip along preexisting joints, and not from tensile extension at the tip of the fracture. Orientations of the principal stresses can be estimated by using fault plane solutions of the larger microearthquakes. By using a joint earthquake location scheme, and/or calibrations with downhole detonators, rock velocities and heterogeneities thereof can be investigated in rock volumes that are far enough from the borehole to be representative of intrinsic rock properties.

Jan 1, 1986

By Peter J. Suardini

Over the last few years, researcher have been working on improving procedures for fine-coal (minus 150 microns) washability analyses. The effort was stimulated by past difficulties in obtaining accurate and reproducible results from the various commercial laboratories providing fined washability services. This paper contains the results from fine-coal washability testing, performed by Process Technology, Inc. (PTI), as part of a U.S. Department of Energy (DOE)-sponsored project. The testing focused on comparing the performance of a number of media options (i.e., aqueous solutions and organic solvents), as well as evaluating the impact of a number of procedural steps on separation performance. The paper summarizes PTI's recommended washability procedures for various size fractions and ranks of coal, and makes recommendations for future studies of certain phenomenon, such as void penetration and particle density changes, which are not well understood.

Jan 1, 1995

By Sibley C. Burnett

Early attempts to apply superconductivity to the beneficiation of kaolin required very large refrigerators to remove the heat generated during rapid charging and discharging of the magnet. In the early 1990's, Advanced Cryo Magnetics, Inc. developed and patented methods to reduce this pulsed heating by a factor of fifteen. Small, helium refrigerators and cryo-coolers are now used. Along with savings in electric power, superconductivity allows operation at higher magnetic fields and greatly improves separation process efficiency. New designs offer enormous reductions in weight, size and capital cost as compared to older copper magnets. Application of this technology to minerals other than kaolin is emerging.

Jan 1, 1999

By George L. Baloo, Dave Kwiatkowski, Jose G. Cañlzales

Capital project funding for a medium to large materials handling project often includes a budget for procurement of supplier-recommended spare parts, and it is the Project Team's responsibility to select these parts. With today's economic climate, limited budget, and other factors, the spare parts selection process is a difficult and arduous effort. This decision carries with it a risk to plant operations and in some cases the commodities producers. Too often the decision-making process is not documented, and the reasons for eliminating and reducing quantities are based on "best guess " Recently on the Solids Handling Phase 2 Project in Jose, Venezuela, the Project Team took a unique approach to this problem. This paper discusses the analytical approach taken by the Project Team, the database system that was developed to manage this problem, lessons learned, and their applicability to pre- project planning and preliminary design.

Jan 1, 2004

By Tim O’Neil

Big and getting bigger. Barrick Gold Corp., the third-largest gold producer in the world, began production in September — ahead of schedule — at its Meikle Mine. At a scheduled full production rate of 12.4 t/a (400,000oz/year), it will be the largest producing underground gold mine in the United States. The $180-million Meikle Mine is located on Barrick’s Goldstrike property in Nevada and has 205 t(6.6 million oz) of gold reserves. The compact Meikle deposit has an average ore grade of 23 g/t (0.68 oz/st), making it one of the highest-grade mines in the country.

Jan 1, 1996

By J. G. Jenkins

Magma Copper Co.'s San Manuel solvent extraction/electrowinning (SX-EW) facility has operated since May 1986. The original facility had a design capacity of 22.6 kt/a (25,000 stpy) of electrowon copper cathode produced by processing pregnant leach solution from an open pit-heap leach operation. In 1988, the plant was expanded to 45.3 kt/ a (50,000 stpy) to incorporate processing in-situ leach solutions. This pager focuses primarily on the heap leaching area with regard to exploration, testing, feasibility, permitting, design and construction, and operating practices. Research using surfactant leaching aids to enhance copper recovery is also discussed.

Jan 1, 1995

By V. Enns, E. Soprovich, J. H. G. Laflamme

A mineralogical and geochemical characterization study was carried out on arsenic-bearing Ketza mine tailings to complement a column extraction test program with the purpose of assessing the potential of arsenic mobilization from the tailings. Two types of tailings samples (i.e., exposed tailings from the impoundment area and water covered tailings samples) were subjected to column tests under standing water cover and with no water cover but weekly flow-through flushing. The tailings have a uniform size distribution. The samples are characterized by high Fe2O3 (44.0 to 68.2 %) and As (3.7 to 4.4w%) concentrations. Ferric hydroxides are the dominant species that are mostly amorphous or cryptocrystalline. Arsenopyrite, scorodite, an Fe-Ca arsenate hydrate phase, an Fe-Bi-As phase and ferric hydroxides are the arsenic-bearing minerals. Arsenic is essentially contained in Ca-As goethite, Fe-Ca arsenate hydrate phase and scorodite. Goethite, although containing low levels of arsenic, could be a significant arsenic-bearing phase because of its high abundance. There does not appear to be any significant chemical or mineralogical difference between the original exposed tailings and the material left underwater with no flow-through for over a year. There are differences in terms of CaO, Fe2O3, SiO,, As, goethite, scorodite, calcite and dolomite concentrations between the exposed tailings and the column material after undergoing approximately two-year flow-through and aggressive leach tests. These differences are likely to be resulting from a combination of different column test conditions and sampling or heterogeneity of the material.

Jan 1, 1998

By C. D. Keith

Erie Mining Company, a pioneer in the iron ore pelletizing industry, has continued to develop methods and equipment to improve cost and quality. Under the management of Pickands Mather & Co., this property, owned by Bethlehem Steel Corporation, Youngstown Sheet and Tube Company, Steel Company of Canada, Ltd., and Interlake, Inc., has initiated a number of operating improvements for the taconite industry. One of the most noteworthy of these, which is applicable to the entire mineral industry, is the principle of fine screening with rappers (FSR). Erie's original efforts in the field of fine screening, which date back to 1961, were described in the April 1967 issue of the MINING ENGINEERING magazine. In that same month, Erie placed into operation a full scale PSR and regrind plant addition, capable of processing 10.3 million long tons of iron ore concentrates, produced by conventional taconite grinding, classification, and magnetic separation methods. Since this first successful commercial operation of the PSR principle et Erie, it has been applied in eight other iron ore beneficiation plants end is being tested by other U.S. and foreign companies. In addition to the use of PSR units at Erie Mining Company, Pickands Mather has applied PSR to other of its managed properties end to projects under development. This paper covers these applications as well as a now application at Erie Mining Company.

Jan 1, 1971