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By Phillips J. T, Hutton W. A

This paper discusses why Argyle Diamonds adopted thickened tailings disposal in 1985 and how the system was developed over the next seven years. A wide ranging review of the thickened tailings disposal system and the tailings deposit it was producing was carried out during 1992 and 1993. The results of that review led to the abandonment of thickened tailings disposal at Argyle because of serious concerns about the stability of the resultant tailings deposit. The exposure to the risk of liquefaction and an assessment of the consequences if this happened to the thickened tailings deposit are shown. The criteria for selecting the new tailings disposal strategy are then described. The final section of the paper discusses the management strategies that have been put in place. These are designed to: ò reduce the risk posed by the thickened tailings deposit to an acceptable level; ò safely store tailings to the end of mine life; ò produce a land form that can be decommissioned to the satisfaction of Government regulatory bodies.

Jan 1, 1996

By P. H. Davenport

"The ore-element patterns in regional lake sediment geochemical survey data from four areas of Newfoundland containing granite-related mineralization reveal characteristics which can be used to identify mineralized granitoids. The St. Lawrence Granite with its fluorite deposits, the Ackley Granite with molybdenite mineralization, the Grey River tungsten lodes and the newly discovered Mo- W mineralization at Granite Lake, Central Newfoundland, have all been included in the regional lake sediment geochemical surveys, which now cover about 90,000 km2 of the Island of Newfoundland. The lake sediments over these mineralized granites show diagnostically high values of Mo, F, Pb, Zn and, in three of the four cases, U, together with locally high Ag and Cu values. Furthermore, these ore-metals display a distinctive zoning pattern about the intrusives, which can be related to the classical ore-metal zoning patterns developed about many types of mineralized granitoids.IntroductionGranitoids in Eastern Canada are receiving renewed interest as potential hosts of tin, tungsten, uranium and related mineralization. Although a number of mineral deposits and showings have been known from a few granites (sensu lato) in the region for many years, granites had generally received little attention as potential hosts of metallic mineralization until the recent resurgence in interest in the mineral potential of these rocks. In Newfoundland, where granitoid rocks underlie about 30070 of the land area, petrologic data are available from some granites, particularly those in eastern Newfoundland (Strong et al., 1974; Strong, 1980), but in southern and southwestern Newfoundland the data base is sparse, and indeed in many cases individual plutons are not delineated on the geological maps of the area . Most of the available data on Newfoundland graniotolds have been summarized by Strong (1980), who gives a general assessment of their mineral potential by comparing their physical, mineralogical and petrochemical attributes with mineralized granites elsewhere in the world."

Jan 1, 1982

By H. Y. Sohn

The ignition and combustion of chalcopyrite particles under suspension-smelting conditions, in which the particle-particle interaction is neglected, has been analyzed by considering the intrinsic kinetics of oxidation and heat and mass transfer between the particle and its surroundings. Reasonable agreement has been obtained between the calculated results and experimental results from a laminar-flow furnace reported in the literature. This computation- al procedure has further been applied to flash-smelting conditions. Under suspension-smelting conditions (Sh = Nu = 2), chalcopyrite particles ignite at around 960 K. The effects of various parameters, such as oxygen concentration, particle size, and gas temperature, have also been evaluated. Comparison between calculated results in this work and experimental observations indicates that SO is the important gaseous product that forms at the surface of the particle.

Jan 1, 1993

By W. Lin, M. J. McPherson

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Feb 24, 1997

By W. Lin

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Jan 1, 1997

Particles of a complex nickel sulphide concentrate (containing pyrite, pyrrhotite, pentIandite, and violarite as the major mineralogical constituents) were entrained in a stream of hot gas the temperature of which was varied from 500 to -1000°C. Chemical analysis of the particulates collected from the furnace was used to detect the rapid change in sulphur content which accompanied the ignition temperature jump. X-ray diffraction analysis was used to characterize the oxidized material.These techniques showed that ignition was dependent on the mineralogical composition and occurred over the temperature range 500-900°C. Pyrite ignited first in the range 500-600°C; pyrrhotite was the least reactivemineral and required temperatures in excess of 800°C for ignition. The nickel minerals <pentIandite and violarite decomposed before ignition and ignited at temperatures intermediate to those required for the pyrite and pyrrhotite. The ignition temperature for the pyrite was found to be independent of particle size and concentration of oxygen in the atmosphere.Ignition temperatures determined by the simulated flash smelting method were compared with the results of differential thermal analysis (DTA) measurements performed on the same concentrate. Temperaturesdetermined in the DTA test as corresponding to the start of exothermic activity were shown to be at least 100°C below those determined by the simulation test.

Jan 1, 1978

By Robert A. Bauer, Paul B. DuMontelle

In 1985, participants of the multi-year Illinois Mine Subsidence Research Program conducted surveys of subsidence effects on crop production from current high-extraction mining methods, selected a site to characterize the profile, strain, fracture development in overburden materials and changes in aquifers produced by subsidence from high-extraction mining, characterized floor materia1 s in three mines, and established bibliographic reference and data base files. The Illinois State Geological Survey, University of Illinois at Urbana-Champaign, Southern Illinois University at Carbondale, Illinois Department of Mines and Minerals and Twin Cities Research Center of the U. S. Bureau of Mines are coordinating State and Federally funded research.

Jan 1, 1986

The southern portion of the Swan Coastal Plain, a geomorphological element formed since late Tertiary times, contains commercially exploitable accumulations of ilmenite, zircon, rutile and monazite associated with a series of raised shorelines. The location of the deposits is controlled by a locally outcropping Archaen granite/ granulite complex and a sea current pattern determined by local geography and a prevailing wind direction. A progression from medium to high titanium ilmenite is evident parallelled by progressive leucoxenisation as the age of the deposits increases. Variations in trace element content accompany this process. Circulating groundwater has caused vertical mineralogical variations within individual deposits and by precipitation of iron has formed layers of hardpan.The Geographe Bay deposits are of important economic significance.INTRODUCTIONObservations made during the course of a brief survey of the southern portion of the Swan Coastal Plain provide an outline of the geology and mineralogy of the mineral sand deposits of the area. This preliminary study will require considerable modification in the light of more detailed work in the future.REGIONAL GEOLOGYThe Geographe Bay area is situated in the south-west corner of Western Australia between longitudes 115° O'W. and 116° O'W. and latitudes 33° 15'S. and 33° 45'S.The general geology of the area is shown in Fig. 1 where the control of the physiography exercised by the Cape Leeuwin-Cape Naturaliste basement ridge is readily apparent. Between this ridge and the Precambrian east of the Darling fault lies the southern part of the Perth basin which contains outcropping Jurassic to Recent sediments and lavas (McWhae, et al., 1958).The Leeuwin-Naturaliste ridge is the exposed portion of L Assistant Production Managcr. Laporte Titanium (Aust.) Ltd.

Jan 1, 1964

By Leon Lorenzen, Charlene Gokhale

"In excess of 24 x 106 tons (Eskom, 1997) of coal-derived fly ash is produced annually in South Africa for the production of electric power. A large quantity of this ash is disposed of as a solid waste in landfills, thus posing a serious environmental problem. Due to the shortage of landfill sites, new ways of utilising fly ash are needed. Recently several authors have shown that various combustion fly ashes can be converted into zeolites to obtain industrial products with applicability in environmental management. Geopolymerisation has emerged during the last few years as a possible solution to some waste stabilisation and solidification problems. henolic compounds have been shown to be toxic to soil microorganisms at the parts-per-million level. Indeed several of the organic compounds classified by the U.S. Environmental Protection Agency as priority pollutants, are phenols. Immobilisation of phenols by adsorption on zeolites and encapsulation in a geopolymer appears to be a promising solution to this problem.This paper reports a technique for the production of a low-silica sodium zeolitic material from fly ash (zeolite NaP1), and its application for the stabilisation of phenols by adsorption and subsequent encapsulation in a geopolymer matrix. A commercial zeolite, clinoptilolite was also utilised as an adsorbent. Due to their uniform pore sizes and large surface areas, zeolitic materials are suitable for ion exchange and adsorption of certain organic substances. Adsorption data show that the commercial zeolite, clinoptilolite was an effective adsorbent for organics. Adsorption data showed that between 51.2 ppm and 74.3 ppm of chlorophenol or between 15.4 ppm and 32.5 ppm of phenol could be adsorbed. Physical encapsulation of the coated zeolite loaded with organic within a geopolymeric matrix increased the compressive strength of the matrix from 28.80 kN to 40.79 kN. Leaching data for the various geopolymer matrices with encapsulated and loaded zeolites show no organics being leached from the system at a detection level of 2ppm. According to the SABS these would have been acceptable organic concentrations within a waste water stream."

Jan 1, 2003

By W. S. Fyfe, G. Southam, T. J. Beveridge

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An invitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold(which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14%within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%)throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999

By G. Southam

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An in vitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold (which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between 80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14% within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%) throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999

By Yang Li

For the study of overburden movement in longwall mining of shallow coal seams, most scholars merely consider the thickness of bedrock and top soils. In this paper, the overburden movement in longwall mining of shallow coal seams with thin top soils and key strata group was studied. By using numerical simulation, the development of fractures in the overburden was analyzed for different ratios of panel width to depth (W/D) and depth to mining height. The results show that the overburden movement changed with the variation of mining height, panel width and depth under the specific geological conditions. It also explain how different overburden disturbance structures, such as ?three zones? (caved, fractured, and continuous deformation zones), ?two zones?(caved and fractured zones) or ?steps-like collapse? are formed under different mining conditions. The results broaden the vision for research on overburden movement in longwall mining of shallow coal seams.

Jan 1, 2014

By Jay F. Colinet

Coal workers’ pneumoconiosis (CWP), commonly known as black lung, is caused by the inhalation of respirable coal mine dust and is a disabling and potentially fatal lung disease with no cure. Historically, CWP has taken a tremendous human and financial toll in the US coal mining industry. Recent health surveillance data indicates that CWP continues to occur at elevated levels. Respirable coal dust exposure must be controlled to prevent the development of CWP. The Pittsburgh Mining Research Division of the National Institute for Occupational Safety and Health (NIOSH) conducts laboratory and mine-site research to identify control technologies that can be used to successfully reduce respirable dust levels. Various technologies, using multiple methods of control, can be applied in order to reduce dust levels. An overview ofCWP’s impact and a general methodology for controlling respirable dust in underground coal mines are discussed in this paper.

Jul 30, 2020

By Pefer F. Stacey

This paper considers some of the trends in slope design technology that are emerging as we approach the 21st Century. While the ability to design stable slopes has unproved greatly over the past 20 years, trends towards steep short-term slopes for small highgrade orebodies, and very high slopes for mega-pits centered on low grade deposits are starting to indicate limitations in available technology.

Jan 1, 1994

By W Valery, A Jankovic

A growing demand within the minerals industry for sustainable development and the introduction of carbon taxes have resulted in a significant focus on improving the energy efficiency of comminution circuits. However, in this drive for improved energy efficiency the role of classification has been overlooked. Inefficient classification and large recirculating loads reduce circuit capacity, result in over-grinding and higher specific energy consumption.It is well understood that classification increases mill capacity; therefore, closed ball mill-cyclone circuits have become an industry standard. However, due to limitations in cyclone classification efficiency, the optimum recirculating load is limited to about 250 per cent. A simple relationship quantifying the effect of classification efficiency and recirculating load on grinding circuit capacity is presented in this paper. The possibility of improving the capacity of ball mill circuits by improving classification efficiency is discussed, considering the current practical limitations of classification equipment. Simulation tools were used to evaluate circuits with cyclones and with high frequency screens to identify opportunities to improve energy efficiency. The investigation also identified potential benefits to flotation recovery due to a reduction in over-grinding.CITATION:Jankovic, A and Valery, W, 2012. The impact of classification on the energy efficiency of grinding circuits - The hidden opportunity, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 65-70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Derek V. Ellis

Coastal and marine mines affect the seabed?s biological resources, eg fisheries, when large volume wastes such as tailings are placed on the seabed, and by the extraction processes from marine mining. Worldwide monitoring of such effects for the past 30+ years now provides information to describe Best Practice design, construction and monitoring procedures. The critical environmental factors for submarine tailings placement (STP) are the selection of an appropriate deposition site and discharge depth, the deposition rate of the tailings, and the speed of biodiversity recovery to a sustainable ecological succession. These should be predictable at new sites using current modeling and experimental procedures. Prediction procedures are still needed to minimize potential destabilization of deposited tailings, and consequent biodiversity recovery setbacks. Comparable environmental information is needed from marine mining sites.

May 1, 2002

By Jan E. Nesset, Phillip J. Mackey

"Studies have shown that there is a correlation between commissioning and start-up time, i.e. time to reach full plant design capacity, and the degree of innovation and technical/engineering uncertainty in the project design. The paper describes the types of start-up curves for plants according to the level of technology or uncertainty in the process design. The need to properly describe and understand the commissioning and start-up time is examined using these curves and the importance on project success is highlighted. A number of case histories of recent mining and metallurgical projects are also reviewed. Finally, the paper reviews how to better assess the level of start-up uncertainty associated with a project and makes suggestions for decreasing the commissioning time due to technological risk.INTRODUCTIOThe start-up of a new mining and metallurgical facility, a much anticipated event, is a critical step in the life of such a project. Achieving a successful start-up and reaching the design capacity on-time requires careful planning, a thorough understanding of the key technological and engineering components involved and a well-trained and adequatelystaffed start-up crew. In this paper, some of the aspects related to start-up of a mining/metallurgical project will be explored, and in particular, the impact of the technology component will be examined. In order to illustrate this, a number of case histories based on recent mining and metallurgical projects will be discussed. Ways of assessing and understanding the uncertainty associated with technological issues related to start-up of a mining and metallurgical plant will also be examined.The history on mining and metallurgy is full of success stories of great mines and mills that are now considered “company makers” (well known examples of such successes include the Horne mine for Noranda which had a 1 year start-up in 1926-27, the Dome mine for Placer Dome, the Grasberg deposit for FMI in Indonesia). Less well documented are specific studies relating to plant start-ups and what constitutes a success or a failure, however there are a few notable references in the literature and these will be reviewed."

Jan 1, 2003

By James R. Garvey

The impact of conversion on the coal industry can be summarized very briefly: We are going to have to mine an awful lot of coal. Fortunately, the United States has the coal reserves available, and given the right conditions, we can mine it. The coal reserves of the United States are enormous. If we consider them on the basis of proved reserves, using the standards of the petroleum industry--that is, resources mapped and explored and recoverable with present techniques at close to present costs--and compare that with the reserves of other fuels, coal constitutes 88 per cent of the proved recoverable energy resources of the nation. That includes oil, natural gas, oil shale and uranium, so long as the uranium is used in burner reactors. If we consider resources on the basis of "ultimate recoverable" reserves, that is, those resources which can be extracted with improved technology and at somewhat higher costs--and if we include those resources of all fuels not yet found but believed to be waiting discovery--coal still accounts for 74 per cent of the national total. We have built a hydrocarbon economy in which about 76 per cent of our total energy needs are supplied by petroleum and natural gas, and about 20 per cent by coal. Domestic resources of oil and gas are running dangerously low and, assuming a continued hydrocarbon economy, the 20 per cent supplied by coal may increase dramatically. We already import nearly a quarter of the petroleum we consume, and the chief source of additional imports seems to lie in the politically unstable Middle East. Natural gas is in even shorter supply, and the problems of importing it seem at least as difficult as those of oil. The fact is, the United States is already relying to an increasing extent on foreign fuel sources. There is an obvious national risk in making an important part of energy supply hostage to foreign governments of uncertain tenure and friendliness. There is also an economic risk--one of the chief reasons for last year's economic freeze was to try to correct the deficit in our balance of payments; it is obvious

Jan 1, 1972

By A. Torkian

Process water from production of concentrates in Meydook copper sulfide mine is transferred to the 8.3 million m3 tailings dam and a water retention pond after initial thickening. Elevated concentrations of heavy metals, sulfate, and TDS and decrease in pH as well as seepage into the aquifers have been the concern of the regulatory agencies since the start of activities. In this paper the results of a 6-month monitoring program from 4 wells are presented. The wells were located approximately 1.5 km from downstream of tailing dam (0.4 km from water retention pond) as well as upstream background well (2.28 km from water retention pond and 1.27 km from tailings dam). The objective was to study possible effect of accumulated tailings on the groundwater resources. Water levels in sampled wells were on average between 20 and 40 m. Results showed high levels of lead (5 ppb), copper (0.17-0.46 ppm) and selenium (73.1- 29.1 ppb). High levels of selenium and lead were partly due to natural geological settings of the area with high levels present in unaffected soils in the vicinity including water wells of villages upstream of mining operations. High copper levels were attributed to both mining operations as well as deposition from particulate air deposition onto the soil and transport to ground water by rain.

Aug 1, 2013

By O. Peters, D. Lascelles, R. Caldwell

Ageing tests on a crushed Cu-porphyry ore were conducted to assess the impact of sample oxidation on flotation performance. The objective of the testwork was to simulate ageing of ore that would be blasted through block caving but not milled for possibly several months. Ageing was performed in specially designed columns, using site and deionised water to keep the samples moist over the entire ageing period. Samples from each ageing interval (0, 0.5, 1, 2, 4, and 8 months) were examined for physical and metallurgical changes resulting from the ageing process through chemical analyses, size analyses, and batch flotation tests.

Jan 1, 2009