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By D Craw, S Clearwater, S Hammit, C Smith

Prior to rehabilitation, plant cover on quartz gravel overburden at Wangaloa coal mine was highly patchy. Stabilisation techniques have since considerably altered the condition of the main overburden yet deposits in the east and west remain largely intact. On the eastern overburden, three distinct zones of revegetation have naturally developed: Zone 1 represents a dense plant cover, Zone 2 a patchy cover and Zone 3 a sparse cover of isolated plants. Aerial photographs show much of the eastern overburden was deposited between 1940 and 1960s. Yet we found that the temporal scale of deposition did not wholly account for the differences observed in vegetation development. To investigate other influential factors, we set up 12 study plots using four replicates in each vegetation zone. The diversity and density of plants in each plot were measured to quantify the degree of vegetation development. Samples from the substrate in each plot were collected using soil cores to a depth of 10 cm. Cores were analysed for indicators of nutrient availability, metal content and physical composition. We found that substrate chemistry varied between individual study plots, but showed little difference overall along the vegetation gradient. Substrate physical differences were much greater. The ratio of coarse quartz pebbles: fines was considerably higher in Zone 3 than other zones, and within zones where plants were not growing. Bulk density also increased successively from Zone 1 - 3. We found clear evidence for the reversed stratigraphy of excavation superimposed over the time scale of deposition, and the corresponding nature of fine particles. The rate of revegetation was therefore highly dependent upon the substrate composition of the last surface deposit from the dumping truck. Our data suggests an optimum ratio exists between inert coarse material and a fine matrix for progressive natural vegetation development on mine substrates.

Jan 1, 2004

By K. Pirapakaran

The Geotechnical Engineering research group at James Cook University has been working closely with all the leading mines in Australia in the area of minefills. They have carried out substantial research and consulting work on the drainage and stress developments within hydraulic fills. The objective of this paper is to summarize their work during the past five years on hydraulic fills. The paper will serve as a one-stop reference, pointing to relevant literature including the authors? own publications, on various issues covering drainage and stress developments within hydraulic fills. More than 15 different hydraulic fills, representing five major mines in Australia, were studied. Their grain size distributions and placement characteristics including permeability, porosity and dry density were studied and comparisons were made with the limited in situ data available in the literature. Stress development within hydraulic fills has been studied to minimize the risk associated with barricades failure. FLAC and FLAC3D were used to model stress developments within the hydraulic fills and were compared against the approximate closed form solutions available in the literature. A laboratory model was developed to study arching effects within the hydraulic fills.

May 1, 2007

By P Mulvey

"Currently mine process studies and geochemical waste characterisation are considered as two interdependent studies, necessary for the development of the mine and inclusion in the environmental impact statement (EIS). Geochemical waste characterisation will utilise the simulated tailings produced by the mine process studies team to understand the behaviour of the tailings, but the two teams rarely integrate these to develop a coherent and agreed final design.Thorough mine waste geochemical assessments can develop processes to minimise environmental harm, resulting in substantial savings in the decommissioning, closure and rehabilitation phases, and may also be able to address changes in mineral processing methods that can result in substantial savings in process inputs, or even recovery of metal concentrates.Based on geochemical waste characterisation, the full cost of waste management can be calculated and incorporated into the costing of milling.  This allows for a more effective evaluation of the metallurgy.  A number of examples are presented in which substantial improvements have been made from the collaboration of both the metallurgical and geochemical teams during planning and the metallurgical team and environmental team during operations.*This paper is only available for individual download. It is not included in the conference proceedings*CITATION:Mulvey, P, 2013. Optimising metallurgy at the planning stage to minimise environmental impact - a feedback loop from geochemical waste characterisation, presented to MetPlant 2013 Conference (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013

By Michael Godard, Peter Cleyle

"Suncor Energy’s Project Millennium increased oilsands production capacity by an additional 95,000 barrels per day to its present level of 225,000 barrels per day. This massive venture included an expanded Mine, new Extraction and Upgrading facilities, as well as, steam and utilities infrastructuresIn the Primary Extraction process, removal of the bitumen from the oil sand begins with slurry preparation and is followed by primary , secondary and tertiary separation processes. The final cleaning step of the bitumen froth is the Secondary Extraction process, that removes residual water, mineral and solids to produce a clean diluted bitumen suitable for Upgrader feedstock.This paper will review the flowsheet of the Millennium Primary Extraction facility, from its recent commissioning through the ramp up to design production rates. In addition, new technologies in the Primary Extraction flowsheet will be reviewed.INTRODUCTIONAs conventional supplies of oil and gas are depleted in Canada, the Athabasca oil sands industry of Alberta becomes an increasingly important source of energy. Today, high quality crude from Alberta’s oil sands accounts for roughly 30% of Canada’s daily petroleum production. According to government projections, over the next 7 years, oil sands production is expected to more then double, and by 2010 more than half of Canada’s crude oil is expected to come from the oil sands.Oil sands deposits consist of a layer of sand saturated with bitumen covered by a muskeg overburden and underlain by silt and clay. The oil sand is mined where the overburden is economical to remove, typically less than thirty meters thick. The Athabasca oil sand deposits around Fort McMurrray is ideal for mining. Bitumen can be described as a diverse collection of hydrocarbons, organosulfur, and nitrogen compounds."

Jan 1, 2004

Assessment of the Consistency Between Different Laboratory Froth Stability Measurements

Sep 13, 2010

By Tara Bajpayee

Modern, highly productive underground mining operations need to assure the safety of their workforce by understanding where major strata fractures and roof failures could occur. Mines depend on a host of tools to assess ground instability. In-mine microseismic monitoring systems with sufficient number of sensors have also been used to provide this information. These in-mine systems must be robust in design and moved regularly to keep up with the mining advancement. System performance issues depend on maintaining ever increasing cable runs, preventing component damage from mining activities (scaling, blasting, etc.) and avoiding signal degradation due to interference from mining equipment (fans, trucks, electrical equipment, etc.). A potential solution is to use a surface based monitoring system having sensors placed in boreholes above and adjacent to the underground mine workings. These sensors must be capable of detecting and locating strata fracturing associated with rock failure events. A great advantage of a surface based monitoring system is its independence from the underground mine infrastructure. There is less concern with cable maintenance problems, signal degradation by interference from mining activity, or loss of power from the mine?s power grid. The disadvantages include the cost of drilling boreholes and challenges associated with placing sensors in the boreholes, maintaining radio communication and solar power, and public interference (vandalism, etc.). This paper describes a case study where a surface based microseismic system, using triaxial geophones in boreholes drilled from the surface, was deployed at a large limestone mine. The system was operational during a roof fall that occurred in October 2007. It detected the first rock fracture event 17 minutes before the rock fall event. The geophone array was sensitive enough to identify all large rock fracture, impact, and blast events as well as medium size rock fracture events occurring close to the geophone array.

Jan 1, 2008

By H. C. Siebert

According to the "Survey of Energy Resources 1980" (1)*, which was prepared by the Federal Institute for Geosciences and Raw Materials in Hannover (FRG)for the World Energy Conference 1980 in Munich, the world coal deposits are assessed at 775 billion tce proven reserves 448 billion tce of them recoverable and 6 161 billion tce additional resources. If one ignores growth rates, the current world coal output of 2,8 billion tpy gives our recoverable reserves a static life expectancy of 175 years. With an average increase in world output of 3,2 % like between 1973 and 1980 this range would be further shortened to an alarming degree. Furthermore, the criteria used to distinguish between workable and unworkable resources give rise to the suspicion that deposit characteristics are not always taken into account to a sufficient degree. For example, little attention is paid to major ?Bonitaet" - factors such as dip and seam thickness. There have been wide-ranging scientific discussions on the lower limit for workable coal resources, but no such limits have been set at the other end of the scale. Otherwise it is well known that performance and costs are badly affected den in level and moderately inclined seams the seam thickness is more than 4 to 5 m, because special mining methods have to be used beyond this limit. These are associated with significantly higher costs than with the winning of seams of ?normal? thickness.

Jan 1, 1985

By N. N. Moelbs

The U.S. Bureau of Mines is conducting research on many topics relating to the hazards of coal mining, increased production, and protection of the environment. One area of research that has received scant attention in recent years is that of water inflows, probably because few fatalities in the United States have been attributed to them. As mining goes deeper, the problem of water in 1ow could increase dramatically because of adjacent or overlying mines in which huge water pools are impounded. Inaccurate mine maps and ineffective barriers can constitute a serious problem for operators both from gradual inflows and sudden inrushes of water. This report describes a wide but ineffective barrier that permitted an average 240-gpm inflow to a developing mine from an adjacent mine. The anomalous geologic structure that facilitated this leakage is described, demonstrating that size, alone, is no assurance against serious leakage. Some recommendations for managing serious water inflow are included.

Jan 1, 1989

By Thomas A. Simpson

Heretofore, underground coal mines in Alabama have operated under only 60 to 360 meters of cover: however, new mines (at least 5 in the early opening or development stages) will be operating under cover ranging from 600 to 660 meters. With increased rock confining pressures, roof stability problems will become more critical. Initial studies in two 7 ½ -minute quadrangle areas in the Warrior coal basin of Alabama indicate that the orientation of certain lineament and fracture-trace modes mapped from ERTS-1 (Earth Resources Technology Satellite) imagery correlate closely with the strike of joint and fault modes. High altitude (118,000 m) U-2 aircraft data were used to support these findings. In addition, over 50 percent of the normal faults mapped in the study area could be directly correlated with ERTS and U-2 lineaments and fracture traces. These correlations provide clues to the structural development of the Warrior coal basin and may, in turn, be used as a guide to the prediction of roof-stability conditions in advance of mining.

Jan 1, 1975

By H. E. Peterson, W. L. Anderson

"INTRODUCTION The great demand for tungsten incident to the war has led to the exploration of a large number of low-grade tungsten deposits. To properly evaluate the low-grade deposits it is essential to have available a dependable method of analysis applicable to all types of low-grade tungsten ores. Results reported on the tungsten content of the ores have often varied quite widely and have led to confusion. The Bureau of Mines has been requested by Government lending agencies and by companies interested in the production of tungsten to publish a general method for the determination of tungsten in low-grade ores. To meet this need, the Bureau of Mines is herein submitting two methods for analysis that have been proved on a large number of tungsten-bearing ores various types in the Bureau of Mines laboratory in Salt Lake City. Also, a third method was developed that requires no cinchonine and has proved to be applicable on most tungsten ores. The cinchonine method is the generally accepted for analysis of tungsten ores. Very reliable results can be obtained by this method if certain precautions are taken, as outlined in this report."

May 1, 1943

SME-AIME Fall Meeting and Exhibit

Jan 9, 1979

Stellite-6 coatings were formulated on two Ni-base superalloys, namely Superni 75 and Superni 600, by a shrouded plasma-spray process, and the oxidation behaviour of these coatings has been investigated in air and in an aggressive environment of Na2SO4- 60%V2O5. Accelerated oxidation tests were conducted in a silicon-carbide tube furnace under cyclic conditions at an elevated temperature of 900°C for 50 cycles. Each cycle consisted of 1 h heating and 20 min cooling in air. A thermogravimetric technique was used to approximate the oxidation kinetics. The corrosion scales were characterised by XRD, SEM/EDAX and EPMA analysis. It has been observed that the coatings nearly followed the parabolic rate law of oxidation. Overall weight gain conceived in air was just 51% of that in the aggressive environment in the case of coated Superni 75, whereas in case of coated Superni 600, the cumulative weight gain in air was found to be one-third of that in the Na2SO4-60% V2O5 atmosphere. Furthermore, the coating showed very good adherence to both of the substrates during the course of air oxidation, whereas some superficial cracks were observed near the edges of the specimens during the molten salt induced oxidation. XRD analysis revealed the presence of phase-like CoO, CoCr2O4 and Cr2O3 in the oxide scales, which are reported be protective against high-temperature oxidation. The XRD results were further supported by SEM/EDAX and EPMA.

Jan 1, 2005

The Bureau of Mines performed cratering experiments in a homogeneous granite to test scaling laws for charge weights of 0.00476, 0.0220, 0.0900, 0.304, and 1.03 lb. Agreement among the data was best when empirical scaling exponents greater than one-third were assumed. Although the analysis showed that the best empirical scaling exponents were 0.37 for crater volume, 0.38 for crater radius, and 0.39 scaling for crater depth, all three crater dimensions could be scaled with a 0.38 scaling exponent.

Jan 1, 1970

By E J. B van Etten

This paper reports on the results of several years of monitoring rehabilitation at a silica sand mine on the Swan Coastal Plain, south of Perth. Mining here occurs below the regional watertable and leaves a post-mine landscape of dredge pond voids (pit lakes) with surrounding battered slopes. The restoration we recommended was to develop the pit lakes as wetlands of regional analogue and value. Several different restoration techniques have been applied to re-vegetate pit lake slopes over many years which have enabled an evaluation of reasons for success/failure of different restoration approaches. Learning acquired clearly showed the benefits of using fresh topsoil for restoration over topsoil that has been stockpiled for several years. Most topsoil used in restoration was from seasonal wetlands and consequently restoration was most successful in the riparian zone from the edge of pit lakes to about 2 m vertically above the water table. Topsoil restored areas above this level remained poor in plant species and cover. Conversely, remedial seeding/planting proved largely unsuccessful. Permanently and seasonally flooded pit lake margins recolonised relatively quickly and successfully with native sedges and rushes. Development of rehabilitated upper slope plant communities over time was evident with loss of typical wetland species and greater growth and survivorship of upland and dampland plant species on mid to upper rehabilitated slopes. Plant communities of lower slopes showed a converse pattern of development, with a shift towards a more typical wetland composition. We believe matching topsoil to site and development of topographic profiles similar to natural wetlands of the region are the keys to optimising restoration success of sand mines with shallow water tables.

Oct 5, 2011

By M. J. Howes

The high degree of mechanisation, which is mainly diesel-powered, has a significant effect on heat loads; heat output from this source often exceeds the heat flow from the surrounding rock. The extensive use of diesel-powered equipment also influences ventilation rates and minimum values are necessary to ensure that emissions of diesel exhaust are adequately diluted. Many Australian mines are in subtropical or tropical areas with high ambient wet- and dry-bulb temperatures on surface. This, coupled with the large amount of heat from mechanisation, usually means that refrigeration is required at much shallower depths. A secondary problem is associated with the definition of acceptable thermal environment conditions, which are sometimes based on the assumption of no air movement. This gives rise to very stringent thermal environment acceptance criteria, which, in some areas, would prohibit work on surface, let alone underground

Jun 12, 1905

By Clarence Hardy Long

In January of 1969 the United States Department of Health, Education and Welfare, through the National Air Pollution Control Administration, published a series of Air Quality Criteria (4'S) and Control Techniques (6,7) for air pollutants in compliance with the 1967 Clean Air Act which will affect the operation of all fuel burning equipment in the very near future. The design of equipment for the future which will use fossil fuels will also be affected. The purpose of this paper is to discuss some of the modifications which might be anticipated in the future for fuel burning equipment. One class of the several air pollutants looked at first by the USDHEW was the sulfur oxides. Other pollutants, such as nitrogen oxides, will be studied and controls for these will supposedly be written in due time. The obvious use of low-sulfur fuels, coal, oil and natural gas is suggested by the Control Technique(6). Conversion to other sources of power, such as nuclear energy and hydropower, is also suggested. The statement is made that since possible hydroelectric sources are limited and nuclear plants are not yet available on a large scale, the changeover to these sources of power will not be overnight. The bulletin (6) suggests that one possible solution in some areas may be the use of low sulfur coals for short periods of time during periods of severe air pollution. A curve showing the effect of this was given in the 1969 April issue of the Power magazine, where A. E. Boyer and F. B. Kaylor of Stone and Webster also described a computer program called DOSAGE which might be used to check weather, temperature, humidity, wind direction and velocity, and sound an alarm when that 0.1% of the time per season is here that requires the use of low-sulfur fuel. Inversion is eminent! Once this has passed operation on regular fuel may be resumed. This would mean a separate storage

Jan 1, 1970

By Immo H. Redeker

This is a final progress report on a cooperative project conducted by three private feldspar companies,** North Carolina State University, and the federal Bureau of Mines. The object of the project was to reduce the feldspar tailings disposal problems at the flotation plants in the Spruce Pine area of North Carolina. The initial phase of the project revealed that high tonnages of saleable feldspar and quartz were lost in the tailings and the three feldspar companies are now concentrating their efforts on feldspar recovery, either by reclamation from the tailings as suggested by the Asheville Minerals Research Laboratory or by improvements in metallurgy in the existing plants.

Jan 1, 1970

By F. P. Haver

The Bureau of Mines has investigated the electrochemical reduction of lead chloride as a method for producing lead without the pollution problems associated with smelting. It was determined that high-purity metal (>99.9 pct Pb) could be obtained, using PbC12 prepared by ferric chloride leaching of galena concentrate: PbS + 2FeCl3?PbCl2 + 2FeC12 + S°. Optimum results in small-scale electrolytic tests were achieved with a bath consisting of 40 to 70 wt-pct PbCl2 dissolved in KC1-LiCl eutectic, an operating temperature of 450° C, a current density of 2.5 amp/in2, and an electrode spacing of 0.5 inch. In large-scale tests made to develop a cell design for commercial application, the optimum electrode arrangement proved to be a bipolar configuration with horizontal plates. This gave a current efficiency of 86 pct with an energy requirement of 0.52 kwhr/lb lead. To determine the effect of impurity buildup in the bath, 1,200 lb of PbC12 prepared by ferric chloride leaching of galena concentrate was electrolyzed over a period of 2 months. Little deterioration of the metal quality occurred in that time; all of the lead produced had a purity equal to or better than corroding grade (>99.94 pct Pb).

Jan 1, 1976

By Harold E. Heide

The United States is the world's largest consumer of tin and depends entirely upon foreign imports for its major source of supply. Only a small quantity of tin is produced on the North America continent. The advent of the war in Europe in 1939?brought a threat to our foreign sources of supply, and the Congress took steps to forestall shortages of tin and other metals. By authority of the Strategic Minerals Act, passed by Congress in 1939, and subsequent legislation, the Bureau of' Mines ?and Geological Survey conducted investigations of domestic tin deposits. Most of the tin that has been produced in North America came from the Seward Peninsula, Alaska.

Jan 1, 1948

By Henrik Saxén, Mikko Helle, Hamid Ghanbari

In this study, a process integration approach in a primary steelmaking is investigated to evaluate future operation concepts of a steelmaking site considering sustainability issues. Mathematical programming is used to study the integration of the steel plant with chemical units for utilization of available off-gases in the system, and carbon capturing and sequestration unit. Different industrial carbon utilization options are considered to find the best route of development. A multi-period optimization model is developed based on site-wide mass and energy balances by considering the availability of the fuels and by-product gases and their consumption in the production system and a conceptual polygeneration system. The objective is to reach maximum economic profit while environmental aspects of integrated system are considered for different fuel systems, alternative blast furnace reductants and implementation of new process technologies. The model can provide useful information concerning techno-environmental and economic aspects for decision-making and can estimate optimal operational condition of current and future primary steelmaking under alternative scenarios. The results of the work illustrate the potential to develop steelmaking towards more sustainable operation in the future.

Jan 1, 2015