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By Jan K. Wolski

Detection of the air recirculation branches within a large ventilation network may be difficult, therefore a PC computer routine has been developed to perform this task in an efficient and reliable manner. This paper describes the method illustrated using a network with complex multi-recirculation circuits. The fact that only the air flow directions and not the flow rates are used in calculations is of some interest. The air recirculation during a real mine fire is demonstrated using the PCVENT program, whose version 4.0 includes current information about any recirculation branches during network calculations or during a fire simulation. This paper also discusses some transient problems related to air recirculation, and gives examples.

Jan 1, 1993

By L. D. Gehi, A. W. Khair, M. Ahmad

This paper presents an analysis of the effect of the dynamics of bit wear on dust generation. Two surveys have been conducted in order to assess the mechanism and type of bit wear and to evaluate the impact of bit wear on the productivity of the continuous miners. Used bits were collected from the underground coal mines and these used bits were utilized in laboratory coal cutting. The effect of bit wear on dust generation has been quantified and its impacted on dust generation and ventilation system has been exemplified.

Jan 1, 1993

By A. Zutshi

Production of CO2 is an inevitable consequence of burning fossil fuels, with the only CO2 sequestration technique feasible in the immediate future being its injection in various geologic media. This paper discusses the factors that influence the injection, movement, and storage of CO2 into deep coal seams, while simultaneously increasing the production of methane. The results of a laboratory-scale study to evaluate the movement of CO2 in coal, its ability to displace methane, and the capacity of coal to retain CO2 are presented. The findings are compared with observations at one of the two field-scale pilot operations practicing CO2 injection in coal. Finally, the paper summarizes the research issues that require further investigation.

Jan 1, 2006

By V. Rajaram, D. P. O’Connor, L. Sakamoto

In 1988, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) imposed a no-blasting specification (blasting is restricted to the construction shaft and shaft bottom or boot) on the Deep Tunnel project. This was prompted by numerous complaints from residents in the vicinity of the project and controversies experienced on previous projects from blasting the rock overlying the tunnel. This paper will describe the methods used by two major contractors driving 20 km (12.5 miles) of tunnel, and drilling more than 36 shafts under this restrictive specification. The impacts are detailed on design, construction, schedule, cost and the environment.

Jan 1, 1993

By W. Douglas Gould, Mei-Lin K. Stichbury, Jeffrey G. Bain, Blowes David W.

The mechanisms of release of arsenic in gold mine tailings were investigated. The highest concentration of dissolved As (75 mg/L) was observed near the base of the tailings impoundment, in close association with a peat layer. Elevated concentrations of reduced iron and hydrogen sulfide were also measured at the base of the impoundment. High numbers of iron-reducing and sulfate-reducing bacteria were detected at depths within the impoundment which correlated with dissolved As, Fe and H2S. The data presented in this paper suggest that arsenic is released from the tailings by bacterially-mediated reductive dissolution of As-bearing iron minerals.

Jan 1, 2000

By J. Yordan, J. Zinterer

Effective removal of ink particles by froth flotation is of up-most importance in paper recycling. In this study, the potential use of talc particles as carriers of difficult-to-float fine ink particles is investigated. In order to accomplish ink particles removal, the interactions between talc and oily- ink particles in aqueous solutions containing flotation chemicals was studied by zeta potential distribution measurements and with the impinging jet apparatus. The chemical conditions under which talc-ink adhesion occurs are identified and reported.

Jan 1, 2003

By P. K. Chatterjee

Before coal can be extracted from surface or underground mines, approval must be obtained from state and federal authorities. Permitting is the application process through which such approval is sought. The application includes en environmental impact statement Which focuses on Such topics as subsidence, toxicity of acid mine drainage, pollution levels of rivers and streams, post mining reclamation, and the effect on the hydrological balance of the area. The permitting procedure is extremely time and labor intensive, and requires extensive interdisciplinary knowledge. This paper examines a LISP based permitting procedure which will help to reduce the time taken to prepare and review a permit application.

Jan 1, 1986

By R. J. Wesely, A. D. Zunkel, Tracy B. Braun, Philip L. LeHoux

An overview of gold processing operations at Barneys Canyon Mine is presented with particular emphasis on ore agglomerating experience, leaching and metallurgical accounting practices, and carbon column plant operating approach. The mine, located thirty kilometers from downtown Salt Lake City, is just eight kilometers north of the Bingham Canyon copper mine. Mining was initiated in February 1989 and the first gold was poured in September 1989. Through year-end 1992, approximately 7 million tonnes of ore have been processed and 12,000 kg of gold have been produced. Gold recovery is in excess of 85 percent.

Jan 1, 1993

By N. S. Harding, M. C. Mai, A. G. Fonseca

Many coal characteristics affect combustion performance. Mill wear, boiler efficiency and derate, slagging, fouling, and ash collection and removal are only a few of the impacts of coal quality on boiler performance. The ability to assess fuel characteristic impacts on busbar costs is essential, although difficult to obtain. The relationships between coal characteristics and ignitability, operability, slagging, and fouling were investigated. The examination of combustion data/performance from a laboratory study, a boiler simulation system (pilot combustor), and commercial boilers indicated the benefits of burning improved quality coal. The specific effects of cleaning are discussed. A validation of the necessity of commercial-scale and/or pilot-scale testing is presented.

Jan 1, 1988

By Scott K. Palm

The initial intent of the Hazard Communication Standard (HCS) was to improve worker health by providing more information about the hazards of chemicals used in the workplace. However, the impact of the HCS goes well beyond worker right-to-know. There are direct costs associated with compliance. In addition, labelling and hazard communications can provide a competitive advantage to producers of minerals that have not been identified as hazardous. Often, the lack of hazardous information about a substance is due to the lack of scientific study, rather than an indication of product safety. Currently, industry and regulators sometimes give known hazards greater weight than unknown risks.

Jan 1, 1991

By William Mark Hart

Newmont Mining's executive management launched an initiative in 1999 that was designed to engage the entire workforce in a continuous effort to systematically drive inefficiency out of the corporation. Built on a foundation of teams and teamwork, Gold Medal Performance (GMP) has had a significant and positive impact on the reduction of costs. At the same time, it has increased productivity, improved cash flow, and helped Newmont to further enhance health and safety programs. Currently, more than a hundred teams are working on improving line-balancing production and external communications at all levels of the corporation. The training and rigorous set of tools avail- able to and used by these teams were designed to help them improve communications, identify inefficiencies and their financial impact, develop and implement solutions, and finally, to measure the results of the process enhancement. GMP harnesses the energy, creativity, and productivity of the entire workforce.

Jan 1, 2001

By R. Mira, S. Rosa, P. Souza

This paper shows the historical data, local geology and mineralization, the mining methods applied, current production,, the planning staff, the resources of hardware and software available and the computer methods used. The activities are described starting with the driving of ramps/research levels, their dimensional parameters and positioning, driving of production sublevels with the same parameters plus those concerned with the stability of the rock mass during the development and the mining itself. Then, the detailing of the ore body is described together with the stopes planning, the openings stability analysis, and the drilling patterns and explosive types are discussed.

Jan 1, 1998

By Anis Farah, Khosrow Aref

Pull-out tests were conducted on cable bolts grouted with concrete, and cement paste. The influence of several parameters on the performance of these cables were studied under loading rates varying from very slow to relatively fast. These parameters include water-cement ratio, cable surface conditions, curing time and embedded length. In addition to being more economical, the results indicate that cables grouted with concrete have higher ductility and ultimate bond strength as compared to those with cement paste only.

Jan 1, 1986

The gases transportation and adsorption in the coal are greatly dependent on the pore-crack parameters, such as the porosity, the pore distribution, as well as the number and size of the pores. What?s more, the pore parameters of the coal are always changing with the temperature. However, the pore characteristics and their changes are extremely difficult to quantify. In this case, Fractal Theory provides a good tool to address this issue. Based on this theory, the pore distribution coupled with the size of the pores can be quantitatively described. In this paper, the equation used to calculate the Fractal Dimension of coal pores was deduced and Mercury Porosimetry was employed to test the pores distributions of coal samples at different temperature. The experimental data excellently verified the Fractal characteristics of coal pores. In addition, the experiments also indicate that the Fractal Dimension of the coal pores linearly increases with the temperature.

Jan 1, 2012

By L. A. Obasi, C. Obasi

Investigations were carried out to determine the effects of changing metamorphic conditions on the formation of magnetite from the Itakpe iron ore deposit. Various magnetite grain sizes from ferruginous quartzites from different zones were determined and analyzed statistically. The results reflect the reaction of mineral individuals. In particular, the granulometry of magnetite changed with changes in the mineral formation conditions in the deposit and correlate with the mineralo-geochemical zones. This is interpreted as part of a readjustment of the mineral to the prevailing conditions. Because granulometry is a prebeneficiation parameter, this work will be, no doubt, of importance to the exploitation and beneficiation of the quartzites and rich ores.

Jan 1, 2000

By Maxine Wiber, Ross D. Gallinger, Brain A. Lewis

Poirier was an underground copper and zinc mine located in Northern Quebec that operated between 1965 and 1975. There are 5 million tonnes of acid-generating tailings, which have contributed acidity and metals to the Kananewesig and Kistabiche Creeks. The final closure plan incorporates the placement of all reactive material into the tails basin, installation of a geomembrane liner over the tailings deposit and a one metre soil layer to protect the liner. The environmental effect of the residual seepage was assessed from an ecological risk perspective. The Reclamation Plan has been accepted, and work commenced in 1998 to restore the site.

Jan 1, 2000

By S. Mathur

Future Florida phosphate reserves contain higher MgO than presently mined deposits. The high MgO content is contributed by dolomite and Mg-rich clay, palygorskite. Selective flocculation was attempted to reduce the MgO content of apatite in synthetic mixtures of apatite with dolomite and palygorskie. Mixed mineral selectivity was predicted in the apatite-dolomite and apatite- palygorskite systems with Poly(ethy1ene oxide) (PEO) flocculant. Loss of selectivity in the mixed mineral systems was primarily attributed to heteroflocculation, which was minimized by addition of a Site Blocking Agent (SBA), a lower molecular weight fraction of PEO, prior to addition of the flocculant. A 80:20 mixture of apatite-dolomite (or palygorskite) was upgraded as 95% apatite at more than 80% recovery level in the product fraction.

Jan 1, 1995

By R. F. Holub, P. J. Dallimore

Basic to solving the problem of the role of radon transport on radon concentrations in mines is to establish whether it occurs primarily as diffusion and forced flow through porous rock or through fissures in the rock. The laboratory experiments performed involved measurements of diffusion and emanation coefficients, porosity and permeability of representative rock samples. Significant differences have been found when comparing the results of the laboratory permeability determinations to those of the mine determinations. Considerations of underlying principles, however, suggest that the diffusion and emanation coefficients are the same in laboratory and mine. It was also found that moisture content plays a dominant role in radon transport through rock. Using these concepts and findings, some conclusions about the radon concentrations in mines have been drawn.

Jan 1, 1981

By Guerry H. McCullen, Bruno Despujol

Quartz and phosphate grains from concentrates and ores from Atlantic Coastal Plain sediments often are wholly or partially coated by humates. Coatings were studied in situ using infrared microscopy, by transmission Fourier transform infrared of extracts, and scanning electron microscopy. The 14C age of the coatings is about 20,000 years, much younger than the mineral substrates. Coatings on double flotation concentrates indicate that the conditioning pH may be too low, allowing coated quartz grains to follow phosphate grains through beneficiation. Organic matter from coatings may contribute to processing problems as well as affect final product quality.

Jan 1, 1999

By Z. Zhang, R. G. Reddy

The viscosities of industrial lead slags of varying compositions were measured as a junction of temperature using a Brookfield viscometer. Based on the experimental data obtained from this study and based on other investigations reported in the literature, an expression was developed to correlate the viscosities of industrial lead silicate slags as a function of composition and temperature. The effect of each individual slag component on the variation of the slag viscosity is identified. The composition dependency of lead silicate slag viscosity is discussed. The calculated results using this viscosity expression are in good agreement with the measured data. Key words: Viscosity, Lead silicate slags

Jan 1, 2003