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Recently discovered Carboniferous bentonites are variable in charadeI and thickness, but being altered aeolian, ash-fall tuffs, they are probably extensive. Most are the Ca-montmorillonite type without the natural swelling characteristics of the Wyoming deposits, but their situation, thickness, and response to beneficiation through cation exchange may give them some potential as sources of future economic deposits.INTRODUCTIONLoughnan and See (1959) gave an account of bentonites and fuller's earth deposits of New South Wales. The most likely potential industrial sources were those occurring in the uppermost formations of the Newcastle and Singleton Coal Measures (Permian) in the Hunter Valley and deposited during epochs not marked by strong contemporary vulcanicity.One feature of the record of known occurrences at that time was the absence of bentonites from the thick volcanic sequences of the Carboniferous, but since this paper appeared, many bentonite beds have been discovered by the writer in the Carboniferous facies formerly known as the "Kuttung Series".The purpose of this contribution is to report briefly on the occurrence, genesis, mineralogy, and economic potential of these deposits which augment possible sources of bentonite near major industrial centres on the eastern seaboard.The potential world demand for bentonite would increase markedly with the trend to pelletization in the steel industry, if its use in this field became more general. More detailed mineralogical studies will be presented in later publications.STRATIGRAPHIC DISTRIBUTIONBentonite occurs at irregular intervals throughout a thick sequence of dominantly continental, plant bearing strata...

Jan 1, 1965

By S Hapugoda, J R. Manuel, M J. Peterson

Microindentation testing using the square–pyramid–shaped Vickers indenter is a well-established technique to determine the microhardness of minerals and materials. However there is a paucity of published microhardness data from Fe ore samples. It is acknowledged that an iron ore’s particle mineralogy and texture is critical to its processing properties, and it is therefore considered that the microhardness of different mineralogical/textural types may also relate to these properties. Mineral microhardness potentially provides inputs to the modelling of breakage characteristics during comminution, as well as the relationship between mineral chemistry and microhardness, and mineral microporosity and microhardness. Microhardness can be determined as single crystal microhardness, for more coarsely microcrystalline samples, or as ‘aggregate microhardness’ for cryptocrystalline or finely microcrystalline samples.Variations in the texture and mineral chemistry of common Fe ore minerals (eg martite and microplaty hematite, ochreous and vitreous goethite etc) are well established and this study provides microhardness data on different textural forms of Fe (oxyhydr)oxides from a variety of different Fe ore deposits. The data indicated that in general, the mineral grain size, microporosity and texture were the main influences on Fe (oxyhydr)oxide microhardness. There were no apparent systematic variations between microhardness and minor element mineral chemistry, with the possible exception of Al content in goethite (for goethites with Al content >0.5 wt per cent), and for goethite total element contents >90 wt per cent (determined by electron probe microanalysis, EPMA). Higher Al concentrations and lower total element concentrations in goethite EPMA analyses correlated with lower goethite microhardness. Microporosity and grain size were more important than texture to hematite microhardness. Different textural forms of dense hematite (eg martite, recrystallised interlocking hematite and specular hematite) with similar grain size exhibited comparable microhardness. Microhardness values for hematite and hydrohematite with little or no evident microporosity were also similar, whereas more porous forms of martite, microplaty hematite or hydrohematite exhibited lower microhardness.CITATION:Peterson, M J, Manuel, J R and Hapugoda, S, 2017. Microhardness testing of hematite-goethite Fe ores – implications for their textural characterisation and geometallurgy, in Proceedings Iron Ore 2017, pp 319–330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

The El Pe±on gold-silver deposit comprises four epithermal, low-sulfidation veins, which contain 2.9 million oz Au and 48 million oz Ag. Provisional data on alteration mineralogy, fluid inclusions, and vein textures constrain the chemistry and hydrology of the hydrothermal system responsible for ore mineralisation at El Pe±on. Alteration minerals include quartz, adularia, albite, illite, smectite, calcite, chlorite, and pyrite. Alteration minerals suggest the existence of near neutral pH, low salinity hydrothermal fluids, which circulated over an area greater than 18 km2. Complex mineral zonation patterns result from variations in host rock permeability and composition, overprinting alteration possibly produced by thermal waters from surficial and peripheral parts of the hydrothermal system, and supergene weathering in the hyperarid environment. Upflow zones were focused along N-S and NE trending structures, producing crustiform quartz-adularia+carbonate veins. Fluid inclusion data indicate vein deposition from low salinity (

Jan 1, 2002

By Derek H. C. Wilton, David T. W. Evans

"Abstract - The Midas Pond gold prospect, central Newfoundland, is hosted by sheared and altered felsic and mafic pyroclastic rocks of the Tulks Hill volcanics, Victoria Lake Group, and has been trenched and tested by 19 diamond-drill holes. Gold values are sporadic, with the best diamond-drill intersection assaying 7.3 g/t over 0.9 m, and the highest grade channel sample containing 14.7 g/t over 1.15 m. Alteration and mineralization are confined to a 200 m wide brittle-ductile shear zone. This shear zone formed in response to regional D1 deformation, and the shear zone fabric parallels the regional S1 foliation. D2 deformation resulted in broad Z-shaped flexuring of the shear zone. The deformation was probably related to the ca. 396 Ma to 420 Ma Salinic Orogeny.Advanced argillic alteration and an extensive halo of Fe-carbonate and pyrite surround the gold mineralization. Alteration minerals include pyrophyllite, paragonite, quartz, plagioclase, chlorite, fluorite, Fe-carbonate, and pyrite. As such, the alteration seems to reflect combined epithermal (argillic) and mesothermal (carbonate) mineralizing environments. The argillic alteration and fluorite represent a regional hydrothermal effect on the felsic volcanic rocks; whereas, the Fe-carbonate and pyrite represent a mesothermal alteration associated with auriferous quartz veins. The Au, which is spatially associated with pyrite, occurs in three structurally-controlled vein sets. These veins are confined to the contact between a highly deformed breccia (the banded mafic tuff) and structurally overlying, altered felsic tuffaceous rocks. The vein sets include: V1 boudinage veins that parallel the shear-zone fabric (C-shear veins), and V2 and V3 extensional fracture veins which are controlled by an S2 fracture cleavage. V1 veins are the earliest and contain the lowest concentrations of Au. V2 and V3 veins are concentrated within the hinges of the D2 flexures.Pb isotope data for galena separates indicate that the Pb in the vein systems was probably of local derivation. Sulfur, C, and O isotope data for mineral separates are similar to data for typical mesothermal lode gold deposits. Fluid inclusion data suggest the presence of at least three hydrothermal fluid types in the region, viz., (1) an early saline fluid which produced the argillic alteration, (2) a CO2-bearing fluid directly related to the auriferous mineralization, and (3) H2O-NaCl fluids which flowed through the Midas Pond shear zone at a lateral distance from the zone of mineralization. The mineralizing fluids are interpreted to have been CO3 -2-rich types which originated through metamorphic dehydration and decarbonation of mixed island-arc and continental crustal rocks. Gold precipitation resulted from the reaction of these fluids with the Fe-rich breccia unit. Pre-existing and simultaneously crystallizing pyrite served as loci for Au precipitation."

Jan 1, 2000

An assessment of methods currently available for the accurate determination of low concentrations of platinum in ores and mineral concentrates indicated that prior treatment of the sample by fire assay procedures is necessary. To enable rapid determinations to be carried out, instrumental methods applied to the metallic bead produced from the fire assay treatment have been evaluated, considering maximum flexibility for concentration variations, minimum chemical operations, and adequate sensitivity.Atomic absorption spectrometry proved suitable, giving solution determination limits of 0·4 p.p.m. Pt, 0·1 p.p.m. Pt, or 0·06 p.p.m. Pt under various extraction conditions using aqueous and organic agents. Thesedetermination limits related to 1 assay ton of sample (32·67 g) produced easily readable and accurate readings within the range of platinum contents (0·03-2·0 p.p.m.) of economic interest in deposit evaluation and prospecting. The technique shows promise of also being suitable for determination of palladium and gold.

Jan 1, 1970

By Eugene McAuliffe

In the year 1581, the counselors of King Philip of Spain suggested to that monarch that a canal across the Isthmus of Darien would open the west coast of the South American continent to Spanish miners and explorers, enlarging and expanding the flow of precious metals then just beginning to trickle across the path cut by Spanish Conquistadors, from old Panama to Puerto Bello on the east coast. The King sent out a party of surveyors and explorers under the command of a young engineer, Savadaerro, who returned after two years, reporting upon a location for a canal which was virtually adopted by the French engineers employed by De Lesseps, who in 1877 commenced the work of constructing the Panama Canal-296 years after Sava- daerro's first survey was begun. The suggestion for an Isthmian canal, made to the king at a time when Spain was a proud, virile nation and when that country was contending with England in the fields of discovery and conquest, represents a measure of vision that has never failed to intrigue the imagination. That the young Spanish engineer recommended an undertaking so gigantic in conception that it took three and one-third centuries for its completion from the time it was first visioned matters little. In the day of Philip of Spain,

Jan 1, 1932

By M. C. Makepeace

"It is the objective of designed experiments to obtain more information for less material and process cost than can be obtained by traditional experimentation. In this paper, the fundamental concepts on which the statistical design of experiments is based are briefly re-viewed according to the following outline: The Experiment The Design The Analysis Two simple 2"" factorial experiments are presented as examples."

Jan 1, 1967

By S. L. Weber, D. E. Banks

"Silicosis was first reported by the ancient Greeks and is apparently as old as human history. The prevalence of this illness peaked in the last half of the 19th century and the early part of this century, when mechanized industry was developing and the relationship between dust exposure and disease was less well understood. Yet, even today in devel-oped countries, sporadic outbreaks of silicosis occur when workers are consistently exposed to silica particles of respir-able size (0.5 to 5.0 µm in diameter) at levels exceeding those recognized to be safe.Silicon dioxide or silica. is the earth's most abundant mineral. Silica is considered to be either free (i.e.. unbound to other minerals) or combined. Minerals with high amounts of free silica include quartz (including granite) flint. Chert, opal, chalcedony, and diatomite. Combined forms of silica are called silicates and include, among others, asbestos talc and kaolin.In the crystalline form, silica exists as quartz, cristobalite, and tridymite (Fig. 28). Of these quartz is ubiquitous in the environment and occurs as sand and as a part of many rocks. Cristobalite and tridymite occur naturally in lava and can be formed by the heating of quartz or amorphous silica. Cristo-balite is more tibrogenic than quartz. Amorphous silica is noncrystalline and, therefore, is relatively nontoxic and does not cause silicosis. It occurs as diatomite (skeletons of pre-historic marine organisms) or as vitreous silica (glass), the result of carefully melting and then quickly cooling free crystalline silica. Heating diatomite with or without alkali (a process known as calcining), forms cristobalite and adds the respiratory toxicity of free crystalline silica.There are many opportunities for occupational exposure to respirable crystalline free silica. Some of the commonly en-countered occupations in which the risk of silicosis exists are reported in Table 20.Silicosis. the pulmonary disease caused by the inhalation of silica particles of respirable size, is most commonly cate-gorized by findings on the chest radiograph. The most typical presentations simple silicosis and progressive massive fibrosis appear different radiologically but are grouped under the category of classic silicosis because they are a part of the radiographic spectrum of this illness. Radiographically, simple silicosis appears as small (less than 10 mm in diameter), rounded opacities, typically predominant in the upper lung zones. Progressive massive fibrosis is the result of the coalescence of these small nodular opacities and appears as larger opacities (more than 10 mm in diameter), again typicallydistributed in the upper lung zones."

Dec 1, 1995

By G. S. Scott

In the course of the investigation into the causes, behavior, and control of mine fires, which the Bureau of Mines is now conducting, some attention was given to the subject of spontaneous heating. It is self-evident that the temperature of a pile of broken coal will rice if the rate of generation of heat exceeds the rate of brat dissipation and will fall if the opposite is the case. Factors that affect the rate of generation of heat are:

Jan 1, 1941

Author's Note: Since the paper on "All-Flotation at North Broken Hill Limited" was read and discussed, the metallurgical results obtained have conclusively justified the adoption of the All-Flotation treatment.At present the shipping grades of lead concentrate produced from North mine ore range between 74% and 75% Pb, carrying approximately 43 oz. Ag and 4.5%-5% Zn. The lead recovery in lead concentrate is recording 95%-96% of the lead content of crude ore, and the milling and treatment cost on 6400 tons crude ore perweek of 96 hours has dropped to 6s. 3.6d. per ton on ore. With an increased ore tonnage, and with a new mill, considerable further reduction in costs is certain.New flotation machines, with 30 in. vertical depth of overflow (instead of 42 in. depth), are now being tried for the secondary granular treatment, with advantageous results. The treatment to-day is practically the same as that outlined in the paper, excepting that additional concentrate is returned for retreatment in the existing units.(Signed) A. LOWRY.Mr. T. A. READ: The author states (page 356 of Proceedings, No. 79), "The sulphide ore itself was then comparatively coarsegrained, a fact which permitted ready concentration of the galena contents by means of jigs, tables, vanners, etc."

Jan 1, 1931

By Robert B. Bittner

The Sutong Bridge across the lower Yangtze River in China will have, when completed, the longest span (1,088 m) and the highest towers (306 m) of any cable stayed span in the world. The foundations for this record setting span will also be record setting. They are located in water depths exceeding 30 m with maximum flows exceeding 3 m/sec. The soil at the site of the main pylons consists of layers of silty sands and silty clays extending to bed rock at 270 m below river elevation. This paper describes the innovative methods used by the team of foundation designers and constructors to support this record setting bridge at this very challenging site. This paper covers three specific topics related to the foundations of the Sutong Bridge: ? Design and construction of the 131 drilled shaft (2.8/2.5 m diameter and 114/117 m long) under each of the two main pylons, ? Design and construction of the scour protection for the two main pylons, ? Construction methods used to construct the waterline pile caps (113.8 m by 48.1 m by 13.3 m deep) under each pylon.

Jan 1, 2005

By G. S. S. Raman, M. S. Klima

Coal refuse slurries stored in tailings impoundments can potentially lead to environmental concerns such as effluent seepage, property devaluation, and in extreme cases, dam failures. Pressure filtration offers an opportunity to reduce the impoundment requirements by providing significantly drier solids. A full-factorial design was used to study the effects of temperature and pH on dewatering a refuse slurry obtained from a coal preparation facility in Pennsylvania, USA. The experimental results indicated a strong effect of temperature on cake moisture as the cake moisture after about 2800 s was 22% at 43 °C and only 36% at 10 °C for tests conducted at pH 3. ANOVA results confirmed the statistical significance of pH, temperature, and their interaction effect. Also, the results showed no significant differences between the tests conducted near neutral and alkaline pH values at low and ambient temperatures. On the other hand, Tukey's test indicated higher reductions in cake moisture at higher temperatures for lower pH values. This study affirms the need to monitor and control the pressure filtration process as throughput could significantly vary with changes in temperature and slurry conditions.

Jun 17, 2019

By G. S. S. Raman, M. S. Klima

Coal refuse slurries stored in tailings impoundments can potentially lead to environmental concerns such as effluent seepage, property devaluation, and in extreme cases, dam failures. Pressure filtration offers an opportunity to reduce the impoundment requirements by providing significantly drier solids. A full-factorial design was used to study the effects of temperature and pH on dewatering a refuse slurry obtained from a coal preparation facility in Pennsylvania, USA. The experimental results indicated a strong effect of temperature on cake moisture as the cake moisture after about 2800 s was 22% at 43 °C and only 36% at 10 °C for tests conducted at pH 3. ANOVA results confirmed the statistical significance of pH, temperature, and their interaction effect. Also, the results showed no significant differences between the tests conducted near neutral and alkaline pH values at low and ambient temperatures. On the other hand, Tukey’s test indicated higher reductions in cake moisture at higher temperatures for lower pH values. This study affirms the need to monitor and control the pressure filtration process as throughput could significantly vary with changes in temperature and slurry conditions.

By G. S. S. Raman, M. S. Klima

Coal refuse slurries stored in tailings impoundments can potentially lead to environmental concerns such as effluent seepage, property devaluation, and in extreme cases, dam failures. Pressure filtration offers an opportunity to reduce the impoundment requirements by providing significantly drier solids. A full-factorial design was used to study the effects of temperature and pH on dewatering a refuse slurry obtained from a coal preparation facility in Pennsylvania, USA. The experimental results indicated a strong effect of temperature on cake moisture as the cake moisture after about 2800 s was 22% at 43 °C and only 36% at 10 °C for tests conducted at pH 3. ANOVA results confirmed the statistical significance of pH, temperature, and their interaction effect. Also, the results showed no significant differences between the tests conducted near neutral and alkaline pH values at low and ambient temperatures. On the other hand, Tukey’s test indicated higher reductions in cake moisture at higher temperatures for lower pH values. This study affirms the need to monitor and control the pressure filtration process as throughput could significantly vary with changes in temperature and slurry conditions.

By LaTasha R. Swanson, Jennica L. Bellanca

Proximity detection systems (PDSs) for mobile machines have the potential to decrease injuries and fatalities. Early adopters of the technology have identified some challenges, which present an opportunity to explore and improve the integration of mobile PDSs in underground coal mines. The current research study applied the task-technology fit framework to investigate the fit between mobile PDS technology and mining relative to health and safety, from the perspective of leaders at two coal mines. Quantitative results from the study show that mine leaders evaluated mobile PDS favorably for training and ease of use, system feedback, user authorization and experience, and less favorably for safety, compatibility, task completion, and reliability. Qualitative results reveal specific task, mine, and system characteristics that may have influenced leaders’ evaluations. The study includes considerations and suggestions for safe technology integration

By LaTasha R. Swanson, Jennica L. Bellanca

Proximity detection systems (PDSs) for mobile machines have the potential to decrease injuries and fatalities. Early adopters of the technology have identified some challenges, which present an opportunity to explore and improve the integration of mobile PDSs in underground coal mines. The current research study applied the task-technology fit framework to investigate the fit between mobile PDS technology and mining relative to health and safety, from the perspective of leaders at two coal mines. Quantitative results from the study show that mine leaders evaluated mobile PDS favorably for training and ease of use, system feedback, user authorization and experience, and less favorably for safety, compatibility, task completion, and reliability. Qualitative results reveal specific task, mine, and system characteristics that may have influenced leaders’ evaluations. The study includes considerations and suggestions for safe technology integration

By E. Nickel

"Bi- and multilateral banks as well as export credit agencies in the OECD countries, but also numerous commercial banks, last year committed themselves to compliance with the World Bank’s standards. These environmental and social guidelines, also known as the Safeguard Policies, are the strictest international standards in the area of financing of major investment projects. The Safeguard Policies are procedural and quality guidelines by means of which socially and environmentally relevant impacts can be taken into account in the planning and implementation phase of a project. Objectives of the Bank Safeguard Policies are to ensure that environmental and social issues are evaluated in decision-making, to reduce and manage risk of projects and programs, and to provide a mechanism for consultation and disclosure of information. They are often referred to as the "10+1 Safeguard Policies," since ten of the guidelines address environmentally and socially relevant issues, while one guideline is exclusively concerned with public participation ("Public Disclosure"). In the presentation, the transparency of risk management measures and emergency response plans in pipeline projects will be discussed as an indicator of sustainability. The discussion is to be carried out on the basis of the results of an evaluation of several major pipeline projects, which have been financed at least in part by multilateral banks over the past few years. The controversies surrounding some of these projects due environmentally and socially relevant impairments connected with the investments have also been addressed by the Extractive Industry Report of the World Bank. Pipeline construction was the investment type chosen for the examination to be presented here, since pipelines frequently start in remote, unspoiled regions, and their routes often cross various natural zones and areas with various social structures. The question of safety during construction and operation of the line is always central to these projects; not only for the responsible authorities but also for other societal groups involved, such as environmental associations."

Jan 1, 2005

By Luis Martín Tejeda

La simulación numérica es considerada como uno de los mejores métodos de modelamiento y planeamiento en la evaluación de la estabilidad de los taludes en minería superficial. En ese sentido, el presente texto señala que a través del método de tensión-deformación, implementado en programas computacionales basados en el método numérico de elementos finitos, se puede llegar a localizar la probable superficie de ruptura. Asimismo, con los diferentes modelos constitutivos como el elástico perfectamente plástico, estos taludes pueden ser evaluados. Por último, se describe brevemente los mecanismos de ruptura en taludes altos, el cálculo del FS y algunas características del programa de elementos finitos PLAXIS v. 7.2.

Sep 19, 2006

The copper-clay deposits consist largely of goethite and clayey mudstones carrying native copper, cuprite, and chalcocite. The mudstones are of Ordovician age, are interbedded with Fe-Mn carbonates, and probably contained syngenetic iron and copper sulphides. The secondary copper minerals have been derived from post-Devonian weathering in situ and also by deposition from surfaee and underground waters draining the adjacent mineralized volcanic rocks.

Jan 1, 1969

Underground mine designs typically try to avoid extraction beneath streams and rivers of any significant size, especially when the overburden rock thickness between the stream bed and the mine is thin. Potential issues with mining beneath streams include excessive groundwater inflow to the mine; weak ground (roof, floor, and pillar) conditions; horizontal stress effects; as well as stream loss and other potential adverse environmental effects. However, there are times when crossing beneath a stream or river is necessary to move into a new area of mineral reserve without creating additional mine access points from the ground surface. Often, stream crossings are completed without thorough assessment, potentially resulting in increased costs, decreased safety, and, in some cases, failure to advance the mine. Selection of the most favorable location(s) to cross the stream must account for numerous factors and the associated assessment often requires a multidisciplinary approach. Stream crossing investigations often require geological, hydrogeological, geotechnical, and geophysical expertise. Phases of stream crossing investigations include desktop evaluation of maps and aerial photography, stream bed observations, drilling, detailed rock core logging, downhole geophysical surveying, hydraulic conductivity testing (packer testing), geotechnical laboratory testing, assessment, and reporting. The deliverables from a stream crossing assessment typically include geological, geotechnical, and hydrogeological characterization of potential stream crossing locations; classification of favorable and unfavorable crossing locations; recommendations for entry design and pillar sizing; and recommendations for if, and how, to conduct pre-grouting activities. Examples of technical aspects of data collection and assessment are provided based on decades of industry experience conducting stream crossing assessments in various underground mining scenarios.

Jul 28, 2020