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By John K. Hollmann

The use of the direct method of determining coal methane content has grown in the last decade from a research technique into a practical coal exploration tool. However, the literature available on the subject is somewhat lacking in site-specific guidance and observations on the conduct of the method and the use of the resulting data. This study discusses some practical lessons learned in conducting a large scale direct measurement project at an operating mine, describes the initia1 interpretations and uses of data from the project, and presents observations from subsequent mine operations into the success and limitations of using direct measurement data in mine planning. The site studied is in central Pennsylvania on the Appalachian Plateau and includes coal seams in the Allegheny series.

Jan 1, 1987

By Toyohisa Fujita, Mitsuo Mamiya, W. Tai Yen, Hiroki Kogita

Green algae taken from an acidic mine drainage and blue-green algae taken from an alkaline hot spring stream were collected and tested for their ability to recover or remove dilute metal ions. Experimental results demonstrated that unwashed blue-green algae and washed green algae effectively adsorbed base metals ions and eluted them at pH 1. It was also found that washed and dried algae adsorbed precious metal ions more effectively than unwashed algae. For example, the washed and dried blue-green algae was capable of adsorbing 0.31 kg of gold per kg of algae. The gold from tetrachloroaurate solution which was adsorbed on washed blue- green algae was found to change to a metallic state following initial metal binding. In the case of a dilute gold complex solution leached with thiourea, only a small amount of gold could be captured by algae. Further experiments were conducted on components of the algae, such as alginic acid, agar, cellulose and chitin and mixtures of these components, in order to determine their contribution to metal adsorption characteristics. However, a mixture of these two components demonstrated both good adsorption and desorption characteristics indicating an interaction between the individual components.

Jan 1, 1995

By H. Sis, D. Dahlin, S. Chander, C. Summers

Bench-scale selective-flocculation tests were conducted on samples of Florida phosphate and Western phosphate process tailings to recover upgraded phosphate concentrates. After physical and mineralogical characterization, the slurry samples were treated with a broad suite of flocculants with a range of molecular weights and anionic functional groups. Parameters investigated included pH, dispersant and flocculant types, and dose; conditioning parameters and settling times were, for the most part, held constant. Where selectivity was achieved, phosphate minerals remained dispersed, whereas silicate minerals flocculated and settled. Single-stage tests using reagents with low to medium anionic characteristics produced upgraded phosphate concentrates at moderately elevated pH. Two- stage site-blocking tests, in which low-molecular-weight flocculants were used as site-blocking agents, gave improved results.

Jan 1, 2002

By S. Mason

Many organizations are realizing that continual improvement in health and safety relies on addressing the potential for various forms of human error. Of these, rule violations are often the most frequent form associated with accidents. These occur when an individual (or individuals) deliberately contravenes established and known safety rules. They have been associated with up to 90% of the accidents and other incidents in some industries, and yet they rarely receive the systematic attention they deserve in the promotion of safety. This paper presents underlying motives that cause violations. These can vary significantly from mine to mine and from job to job. Managers need some measure of the attitudes of the violators to determine the underlying motives behind the violations if they are to determine effective strategies for promoting safe behavior. Questionnaires form the starting point to address attitudes and the motives behind rule violations. The choice of the most suitable questionnaire, how- ever, will vary from organization to organization. Guidelines on the choice of questionnaire are offered.

Jan 1, 2000

By Ing Newton Amegbey, Joseph Afari Idun

Ashanti Goldfields Corporation (Gh) Ltd., the leading gold mining operation in Ghana is embarking on a major rehabilitation and expansion programme to increase gold production. A new southern ventilation district was targeted for this programme, and the ventilation system was to be reviewed in order to cope with increased production. The southern ventilation district was previously ventilated by booster fans. This arrangement was however, inadequate to solve the problem of the need to reduce smoke clearance time of the production areas, and to generally improve the underground ventilation conditions. Fan maintenance costs increased with the number of fans installed in the booster fan arrangement, and the fact that the fans were installed underground made maintenance difficult and took longer time. It became necessary to consider the installation of a new main fan on the surface. This paper gives an overview of the ventilation systems of the southern ventilation district of the mine before and after the new main fan was installed. The field tests carried out on the fan to ensure that it complied with supplier's specifications are described, and the new system analysed to see it's effectiveness.

Jan 1, 1993

By Swati Mohanty, G. V. Rao

Sedimentary dolomitic phosphate ores are difficult to treat by flotation, and high-grade phosphate concentrates with high recoveries are difficult to obtain. The literature indicates that the reagents required for beneficiation of such ores are generally dictated by the nature of the gangue. In this paper, the optimum flotation parameters necessary for enhancing the grade and recovery of a typical low-grade dolomitic rock phosphate ore from Jhamarkotra, Rajasthan, are highlighted. The standard design-of-experiment (DOE) technique was used to obtain empirical models for both grade and recovery. The model equations were then used for optimizing the flotation parameters, including pH, percent solids, collector dosage and depressant dosage. Laboratory experiments demonstrated that a phosphate concentrate containing about 36% P205, with a recovery greater than 95%, can be obtained in a single-stage by the reverse flotation of carbonaceous minerals at the optimized conditions. Key words: Phosphate, Flotation, Dolomite

Jan 1, 2003

By Kenneth Maser, Douglas W. Ounanian, Joseph S. Boyce

Foster-Miller Associates, Inc. (FMA), under contract to the Department of Transportation (DOT) and the Urban Mass Transit Administration (UMTA), is currently developing an Extruded Tunnel Lining System (ETLS). The ETLS would reduce ground support costs in machine bored tunneling by eliminating the need for temporary support, and by slip-forming the final concrete lining directly behind the Tunnel Boring Machine (TBM). The system can advance at variable rates, from 0.6 to 3.7 m (2 to 12 ft) per hr, by combining three systems: a very high early strength concrete, continuously produced and delivered by a concrete process system; a slipform/bulkhead system for supporting the concrete prior to strength gain and exposure; and a control system for form/bulkhead alignment and concrete process control. Large-scale tests are planned to demonstrate the system in a 3 m (10-ft) diameter steel "tunnel".

Jan 1, 1981

By J. K. Ahlness

The US Bureau of Mines investigated technologies for determining the integrity of in situ leach mining wells. A self-contained trailer-mounted well integrity testing system (WITS) was designed and built to enable rapid testing of well casings for leaks as required by environmental regulations. The WITS utilizes two inflatable packers to seal off the entire casing length or any portion thereof. Water pressure is built between the packers to the desired test pressure, and the presence or absence of casing leaks is determined by monitoring the pressure drop between the packers. A winch and steel cable are used to run the packers in and out of the well. The WITS underwent an industry field test at the Irigaray in situ uranium leaching mine near Buffalo, WY. A total of 37 wells with an average depth of 69 m (225 ft) were tested at an average rate of four wells per eight-hour shift with a two-person operating crew. This represents a 75% time savings and an 83% labor savings compared to the rigid-pipe method previously used at the mine, with which a three-person crew tested an average of one well per shift.

Jan 1, 1988

By S. Kesler

Rössing Uranium Limited has operated since 1976 a large open pit uranium mine and extraction plant at a remote site in the Namib desert, South West Africa/Namibia. The geology (Berning, I., et al. Economy Geology) and the technical aspects concerning mining, grade control and metallurgy have previously been described (Rössing Uranium, Mining Magazin and Whyllie, R.J.M. "Rössing Uranium reaches rated production", World Mining). The improvement of leach 'extraction has been reported in 1984 (Kesler, S.B. et. al. "Uranium extraction at Rössing") and the installation of a central process control system has been described (Kesler, S.B. et al. "The introduction of a central process system at Rössing"). At the beginning of 1983 a decision was made to develop a computer system for metallurgical plant optimisation which included mass and volumetric balances, analytical assays for up to 5 chemical elements and the costs for the major consumables. Within 10 months this computer system was developed and implemented. A large number of test runs were made and computer studies were undertaken. The metallurgical division now has a scientific tool for production; planning for actual comparison with plant results and for strategic investigations and decision making.

Jan 1, 1986

By S. Chander

The advantages and disadvantages of various techniques available for controlling reagents in the mineral flotation systems are discussed. Special interest is placed on potentiometric and voltammetric sensors for monitoring flotation pulps. Different approaches to increase the sensitivity of detection and to facilitate in-stream monitoring of solution species are also discussed. The potentiometric sensors are simple to use but are limited by the availability of an electrode reversible to the species to be monitored. In some cases the response signal could be unreliable due to the presence of interfering species. In comparison, voltammetric sensors require a higher degree of instrumentation which, however, provides an opportunity to decrease interferences and increase levels of detection.

Jan 1, 1993

By R. Kanniganti, M. Karmis, C. Haycocks

An extensive review of multi-seam under-mining literature was conducted and a data base of case studies was assembled . A critical review of the design principles outlined in this literature resulted in the compilation of specific design criteria for the design of lower seam mines. Analysis of this criteria demonstrated the necessity for a protocol for the design of unsymmetrically loaded pillars. Such a design criteria was developed using finite element methods for a wide range of possible loading conditions. This design criteria can be utilized for underlying pillar design when the loading conditions can be determined. To facilitate using all the under-mining research results by field/planning engineers a Windows TM based software package was developed. This software package contains a multi-seam tutorial, analytical tools and a case history database. The package is user friendly and fully interactive and supported with extensive on-line help. The package contains numerous case studies of multi-seam mines that can be reviewed to facilitate analyses.

Jan 1, 1996

By Jouko Suominen

The basic development of various mining equipment has been strongly influenced by two objectives; improving economic results and safety aspects. Both of these factors contribute to increased requirements of mechanization and automation in different parts of mining processes. When we are limiting the discussion the crushing circuits, automation has two dimensions, one being the component automation, or intelligence, the other being automation of complete processes. Both of these subjects are closely tied up, the former being a condition for the latter. The key technologies of crushing automation are transducers, programmable logics and computer software. Also equipment technology continually faces new challenges, which result even in totally new product families. One example of this kind of development area the track-mounted, integrated crushing systems, where design criteria have been simple control, unmanned operation, and flexibility in changing requirements. This crushing system, or philosophy, offers excellent possibilities for new concepts in various underground and open pit applications, connected with automatic process control. Following presentation is a summary of aspects, of haw a crusher manufac¬turer sees the development of automa¬tion as an integral part of equipment technology and development.

Jan 1, 1989

By A. Yehia, J. S. Hu, J. D. Miller, M. Misra

Fluoride activation has been evaluated by Hallimond tube flotation of collophanite in terms of fluoride concentration, conditioning time, pH, and temperature. The results reveal that efficient oleate flotation of collophanite can be achieved by fluoride activation. Experimental results of fluoride adsorption by collophanite suggest that, at low fluoride concentration, a fluoroapatite-type compound may form on the collophanite surface by chemisorption of fluoride ions at calcium sites. At high fluoride concentration, calcium fluoride appears to form at the collophanite surface involving a surface precipitation phenomenon. The formation of CaF2 on the surface of fluoride-treated collophanite is further substantiated by the FTIR spectroscopic measurements, which suggest a metathetic exchange with phosphate from the collophanite lattice during the surface precipitation process.

Jan 1, 1988

By J. A. King, D. R. Weir, P. C. Robinson

Preconcentration of Porgera ore results in high recoveries of gold into gravity and flotation concentrates. The bulk of the gold is contained in auriferous pyrite flotation concentrate and is not readily recoverable by direct cyanidation. Oxidation in autoclaves at high pressure and temperature produces a residue that contains the gold in recoverable form. Pilot plant treatment of the autoclave residue is described, through washing and jarosite decomposition stages, to cyanide leaching and recovery of gold and silver by carbon-in-pulp techniques. The concern associated with disposal of plant effluents are also addressed.

Jan 1, 1987

By Randal J. Barnes

Computer based techniques for solving the Ultimate Pit Limit Problem have appeared in mining literature since the early 1960's. The majority of papers pertaining to this subject can be partitioned into one of two categories: discussion of the pros and cons of a particular algorithm, or a case study presenting specific applications of an algorithm. Subsequently, there has a1 so been considerable debate concerning the best techniques between, essentially, two camps: those favoring the moving cones techniques, and those favoring the techniques which yield true optimal pit designs. The purpose of this paper is not to add to this debate, but rather to present a few new ideas (partially a new look at an old idea), which can be easily implemented to noticeably improve any ultimate pit limit approach independent of the particular algorithm used. These ideas fall under the heading of "bounding the optimum" (Barnes and Johnson, 1980).

Jan 1, 1982

By K. Severin, B. Flanigan, P. Marion

"Plutonic-related" gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As- (Sb-Hg) are a good empirical indicator of the depth of emplacement and distance from causative pluton. These associations have been used successfully in exploration. Results from several analytical techniques also suggest a phenomenological cause for these metal associations. Gold and bismuth have paired mineralogy at high temperatures and, thus, are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2003

By P. Schiavi

A trend towards the independent verification of sustainable development reporting and assessment using third party certification can be discerned in the global minerals industry. Various codes that provide for the third party assessment and certification of performance against a range of externally developed sustainability indicators are being adopted by minerals companies, and there is also considerable activity in the broader area of third party assurance. Using a sociological approach, this paper examines the reasons why third party certification schemes are appearing in the minerals industry to address sustainable development imperatives in preference to other forms of regulation, and considers the broader implications of this trend. Data are drawn from a series of qualitative, in-depth interviews conducted with some of the key players in the development and adoption of certification schemes in the minerals industry, with executive managers of a range of large mining corporations, with representatives of global non-governmental organizations that are active in mining issues, and with government officers responsible for the regulation of mining corporations in Australia. Factors responsible for the emergence of the new certification schemes include: increasing demands from stakeholders for greater credibility in reporting against sustainable development indicators; broader contextual factors including globalization and neoliberal policies; and issues relating to trust and risk. Using insights from our research, and the work of others in this field, we identify some of the critical features of a credible third party certification scheme, and note some of the challenges for the design and implementation of such schemes. We conclude by discussing some of the broader implications of third party certification as an emerging form of regulation in the minerals industry.

Jan 1, 2007

By Leonhard Schmid

INTRODUCTION In the region of Zurich several of the Swiss Interstate Highways meet and have to be linked to form a continuous network. The subalpine glacial topography with hills, ridges and lakes requires the construction of many tunnels (Figure 1). The Milchbuck Tunnel forms part of the inner arterial highway system of the city of Zurich. It passes underneath the ridge separating the Limmat and Glatt valleys. In its final configuration the tunnel will consist of two parallel three-lane tunnels (Figure 2). For the time being only one tunnel is constructed. This tunnel will be operated with two outbound (climbing) lanes and a single inbound (descending) lane (Figure 3). The owner, the Canton of Zurich, awarded the contract for the construction to a joint venture with the following three contractors: Locher & Cie AG (leader), Prader AG, A. Brunner's Erben, all located in Zurich. The actual freezing was performed by subcontractor Philipp Holzmann AG, Mannheim, West Germany. Electrowatt Engineering Services Ltd, Zurich, was design engineer and performed the construction supervision.

Jan 1, 1981

By A. Tsouchlaraki

The physical relief is a variable of utmost significance in the course of the analysis, evaluation, design and management of the visual environment. In this sense, there are cases where it would be desirable to isolate the relief from the other elements making up the visual environment and to investigate its visual value separately. Such cases include the technical works that cause major and permanent alterations to the relief, as well as the works, of which the spatial arrangement depends on the morphology of the ground. Slopes, distances, hypsometric difference values, viewsheds are elements of the relief that affect the visual value of a landscape, but also the ability of a particular landscape to accept and absorb new activities. This paper describes an evaluation and prediction model of the visual value of the landforms. A questionnaire survey takes place in order to investigate the public preference, using a sample of 221 persons in the broader area of Athens. The means used to demonstrate the various forms of reliefs are 32 perspective digital relief images. Following this and in order to investigate the elements of the relief that affect its visual value, 20 quantitative indices were developed and examined so as to select the best ones. Linear prediction models of the visual value were investigated from the previous elements, through a regression process. The applications of the proposed model in physical environment planning are many, such as the prediction of visual impact by arranging works that alter the relief of a region, as it happens in mining, metallurgical and waste disposal sites.

Jan 1, 2005

By G. B. Misra

Though installations of main mine fans vary widely, the commonest installation is of a surface exhaust fan connected to an upcast shaft some distance below its collar by a horizontal fan drift bending sharply. downwards near its junction with the shaft. The junction of the fan drift with the shaft often causes considerable shock pressure loss if not properly designed. In one of the major coal mines in India circulating 180 m3/s of air through the mine a pressure drop of 229 Pa out of the total fan pressure of 568 Pa occurred at this junction while in a smaller gold mine circulating 9.4 m3/s it was 147 Pa out of a fan-drift pressure of 382 Pa. With larger mines circulating larger volumes of air, ill designed fan drifts can lead to considerable wastage of the power of ventilation. Shock loss at the junction of fan drifts with exhaust shafts depends on (1) the angle of deflection of the bend, (2) sharpness of the corners (both inner and outer) at the junction, (3) the degree of contraction of the flow-stream which depends on the cross- sectional area ratio of the shaft and the fan drift as well as the amount of leakage through the shaft collar. It must be noted here that the friction pressure loss in the bend is negligible compared to the shock pressure loss.

Jan 1, 1980