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By G McKay, M Erskine, S Macklin

The City of Sydney is currently investing in a number of infrastructure projects that require tunnel excavations within the Triassic Hawkesbury Sandstone. It is generally accepted that this formation has high residual stresses of ‘tectonic’ origin, so much so that these stresses have been implicated in a number of well-known failures and problems for tunnelling. These include failure of ‘roof beams’ comprising discrete beds in the crown of tunnel excavations; stress-induced spalling and ‘slabbing’ of tunnel walls; shear displacement between beds causing the failure of rock bolts; strain in adjacent infrastructure and, the necessity for re-grouting of high conductivity fractures due to stress relief dilation after excavation. Whilst there is an extensive published database of in situ stress measurements comprising ‘hydrofrac’, ‘over-coring’ and ‘slotter’ stress measurements, these data indicate a considerable spread of results. The traditional approach to interpreting this data has been to attempt to fit linear correlations to stress versus depth data, based on personal experience and ‘back-analysis’ of monitoring data during construction. However, there are a number of such correlations in the literature and there is divergence of opinion regarding the assessment of ‘background’ in situ stress and appropriate upper and lower bound values for design. This paper provides a brief review of the published data; suggestions on an alternative ‘risk-based approach’ to assigning in situ stresses for design; and, proposals on how in situ stress tests may be conducted in future to improve the quality of the database available to designers.CITATION:Macklin, S, McKay, G and Erskine, M, 2014. A review of the in situ stress database for tunnel design in the Hawkesbury Sandstone, Sydney, New South Wales, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 171–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

The Particulate Mineralogy Unit has been established at the College Park, Maryland, Metallurgy Research Center. The Particulate Mineralogy Unit will have the responsibility within the Bureau of Mines for the characterization of particulate minerals which have potential for adverse environmental effects. The Unit will provide a focal point for identifying particulates in connection with environmental problems related to the activities of agencies such as OSHA, HEW, EPA, and MESA. The Particulate Mineralogy Unit is seeking to clarify the ambiguities surrounding the mineralogy of and terminology used for asbestiform minerals and other mineral particles. The Unit?s investigations of the morphology, composition, and structure of asbestiform minerals and their nonasbestos analogs have made its members recognized experts in this field. The information which it develops on the characterization of asbestos and other particulate mineral forms such as silica should provide a technically rational basis for decisions by regulatory agencies. Those desiring further information, contact Dr. W. J. Campbell, Program Coordinator, College Park Metallurgy Research Center, College Park, MD 20740, telephone: 301-344-4014. ALUMINUM: For over a month, domestic producers have priced 99.5 percent grade primary aluminum ingot at 48¢ per pound. In the same period, merchants raised ingot quotes by 1.5¢-2.5¢ to a range approaching 44¢-47¢ per pound.

Jan 1, 1976

By Sara J. Davenport, Genevieve Morgis, J. J. Forbes

"This circular is part III of a series of papers reviewing the literature on air conditioning in mines, with particular reference to the health, safety, and efficiency of miners.4/ It deals with theoretical and practical methods of conditioning air in mines to correct or alleviate the health hazards described in parts I and II and discusses the results attained by some of the systems now in use in various-parts of the world.The principal conditions to be corrected or alleviated are the chemical qualities of mine air (especially when contaminated with toxic and noxious gases and dusts) and the physical qualities (abnormal mine temperatures and humidities) that emanate from various sources in underground workings. Air motion and barometric pressure are physical qualities also to be considered.From the standpoint of health, knowledge of the composition of the air, or atmosphere, in mines and other underground operations is of prime importance. Suitable control measures or plans of procedure to combat or eliminate the hazards from contaminants must be based upon accurate information obtained by the selection and use of proper methods of sampling and analyzing mine atmospheres (1).5/Conditioning air is one of the most essential factors to be considered in any underground workings, not only from the standpoint of health and safety but also with regard to efficiency and productivity. Without modern air-conditioning, the war's great demand upon the copper mines could hardly have been met, as the mechanical refrigeration cooled off sweltering holes in less than a month, whereas in the past it was standard practice to blow air through the tunnels for 3 years or so until they were cooled.This paper discusses methods of determining the chemical and physical qualities of mine air and their control. Briefly, the following points are presented:"

Oct 1, 1949

By Scott, Turner

IN 1933, the monetary metals were produced in a ratio of 6.7 oz. of silver to 1 oz. of gold, the lowest relatively for silver since the period from 1851 to 1865. At the beginning of that period, the virgin placers of California -and Australia began producing almost simultaneously; in consequence, there was an abrupt fall in the high silver side of the ratio that had prevailed through the centuries after America was discovered. The output from the Comstock and other silver-bearing lodes, located a decade after this influx of new gold began, soon restored the production ratio to its former proportion, that is, a relatively large weight of silver compared to gold.

Jan 1, 1934

By Grant R. Brown

The report provides guidance for determining those environmental impacts associated with the surface mining of steeply pitching coal seams. In addition to the environmental impacts, four additional issues are addressed, namely (1) Time and motion studies of those coal mining systems employed in mining seams which pitch in excess of 25°, (2) Assessment of those mining techniques, (3) Development of rationale for the mining methods employed, (4) Identification of the reclamation practices and determine whether these practices were in compliance with appropriate Federal and State regulations. Five surface mines located in three geologically distinct basins of the United States were analyzed during the period of August through November 1979. The three basins include the Hanna Basin of Wyoming, the North Park Basin of Colorado and the Southern Anthracite Field of Pennsylvania.

Jan 1, 1980

By D. L. H. Forbes

(New York Meeting, February, 1912.) Introduction.. THE application of the cyanide process to complex sulphide ores for the extraction of their bold and silver is no longer a novelty, but, as an example showing modern tendencies in this direction, the following description of the new milling process at the Lucky-Tiger mine is offered: The extraordinary richness of the ore in the upper workings of this mine made any thought of milling in its early hays seen unnecessary. Its location in an almost inaccessible part of the rugged mountains just south of the Arizona boundary-line, and 60 miles from the town of Douglas, made the expense of bringing in machinery and supplies a very serious consideration. But, after the property had been shipping high-grade ore on mule-back for a few years, there remained in the mine a considerable tonnage of vein-matter that was too low in value to ship, but which it was thought could be milled near the mine at a profit. The first milling-experiment consisted in the installation of Nissen stamps in conjunction with concentrating-tables and Frue vanners, but, as the ore from the upper workings contained most of its silver in the form of cerargyrite, this type of mill was not successful. The proximity of the mine to the great copper-concentrating mills of Cananea and Moctezuma naturally made the influence of copper-milling, ideas felt in the company's next installation. At considerable expense a stage-crushing concentrating-mill, with a capacity of 100 tons per day, was built. This mill was modeled along the lines of the most approved practice in copper-concentrators at that time, the main idea being that crushing by stages in rolls was necessary in order to prevent losses from ?sliming." Largely owing to the fact that, when the mill

Aug 1, 1912

By G. Scamans, J. Lazaro-Nebreda, Z. Fan, J. B. Patel

"Melt quality is crucial for both continuous and shape casting of light alloys and in order to improve it, removal of excessive inclusions, accumulated impurities and unwanted gases becomes necessary. To address this problem, a new multi-purpose high shear liquid metal treatment technology, based on intensive melt shearing by a rotor/stator unit, has been developed. The device ensures achieving uniform temperature and chemical composition and an efficient dispersion of gas and solid phases in the melt with minimal disturbance of melt surface, and can be used, among other things, for de-gassing and de-ironing of Al-alloy melts. Efficient degassing is achieved by dispersing each argon bubble into many small ones, which significantly increases the overall surface area of the bubbles and the time they remain in the melt capturing hydrogen before reaching the surface. This allows using much lower inert gas flow and mixing times than conventional rotary degassing. When applied to Al-alloy scrap, with accumulated iron, the high shear melt treatment speeds up the nucleation and growth of primary Fe-rich intermetallic particles, allowing a faster removal rate. Therefore it reduces processing times, increasing recycling productivity, and facilitates full metal circulation of secondary Al-alloys.INTRODUCTION Aluminium and magnesium alloys are widely considered in various industrial sectors for the purpose of weight saving (Polmear, 1995). In particular, they are used in the automotive sector, where components are mostly manufactured by high pressure die casting (HPDC) because of its simplicity and relatively low cost, but efficiency and mechanical properties are quite low compared with other processes. To date, the main focus to overcome this problem has been for improving the HPDC machinery (Dahle, 2001) but little attention has been paid to the opportunities of controlling the nature and quality of the molten metal supplied to the die. In this way, liquid metal treatment, which involves a variety of physical and/or chemical processing methods to improve melt quality prior casting, is crucial for both continuous and shape casting products."

Jan 1, 2018

After a snap-shot survey of water quality of streams draining various coal measures carried out in 2000 - 2001, West Coast Regional Council expanded its monitoring programme to better establish the condition of streams draining coal mining areas and to characterise the variability of water quality with respect to stream flow. Samples were collected for water quality indicators such as pH, sulphate, turbidity, conductivity, temperature and dissolved oxygen as well as macro-invertebrates, fish and assessments of stream habitat. Water quality sampling was carried out at 27 sites on 21 streams located from Page Stream near Seddonville in the north, to Seven Mile Creek near Dunollie in the South, and to Garvey Creek east of Reefton. There was relatively low variability of pH, conductivity and sulphate concentrations at most of the sites sampled. Conductivity and sulphate concentrations reduced with increasing flow and pH generally increased. Significant effects on macro-invertebrate and fish populations were identified at several of the sites where water quality sampling was undertaken. Of the water quality parameters tested, macro-invertebrates were mostly affected by pH. Although not sampled directly (conductivity was used as a surrogate) heavy metal concentration may explain some of the variation in macro-invertebrate communities. Three creeks affected by mine drainage were sampled for fish and no fish were present. Fish appear to be more sensitive to acid rock drainage that invertebrates. Using data from this survey and other studies conducted in the region, the total length of stream that is actually or highly likely to be adversely affected by acid rock drainage was estimated at 125 km. This figure is useful as a gauge as to the magnitude of the issue in this region and for setting of priorities for remediation. However, as it is only an estimate based on limited sampling sites, it should be used with caution.

Jan 1, 2003

CONTENTSSummary.Introduction.Location and Geology.Historical and Exploitation.Part 1. Washability Characteristics of the Liddell.Seam.Foybrook Open Cut, Top Bench.Sampling.Size and Ash Distribution.Washability Data.Washery Separations.Part 2. Washability Characteristics of the LiddellSeam.Foybrook Open Cut, Bottom Bench.Sampling.Size and Ash Distribution.Washability Data.Washery Separations.Acknowledgments.References.INTRODUCTIONThe washability characteristics, size-range and chemical analyses of the screening from the Liddell Seam are matters of growing interest in view of the increased exploitation of this seam over the last few years, and also since the Newdell Coal preparation plant of the New South Wales Mining Company Proprietary Limited, utilizing magnetite heavy media separation, commenced...

Jan 1, 1954

By G. Richards Gwinn

The mineral graphite, a form of carbon, has been known for hundreds of years, and, was first used commercially as a coloring agent. Its true identity, however, was not recognized until the end of the eighteenth century, and its commercial development did not become extensive until near the close of the ninteenth century.

Jan 1, 1943

By W. W. Adams

The first full year of the second World War for the United States presented a picture of the metal-and nonmetal-mining 4 industry which, without proper analysis and explanation, would convey a distorted view of achievements during 1942, especially because employment at gold and silver (lode and placer) mines-the largest group-declined to such an extent that the over-all totals for the country were reduced even though increases were made at mines producing copper, lead-zinc, iron, miscellaneous metals, and non-metals. A complete panorama of the metal-and nonmetal-mining industry, exclusive of coal mining, reveals a decrease in the number of men employed, the man-hours of employment, and the accident-frequency rates. Were the gold and silver (lode and placer) mines to be considered as a separate category; it would be seen that the number of men employed at all the other groups of mines increased appreciably over 1941. These other increases must be considered important, since these mines produced the vital war minerals that made valuable contributions to the military successes of the United States and its Allies during the year. A separate analysis of each of the various groups of mines may be found elsewhere in this bulletin. For the purpose of maintaining continuity in this series of bulletins, however, the discussion in this introduction will be confined to the entire metal-and nonmetal-mining industry (excluding coal mining, for which a separate bulletin, No. 462, has been published).

Jan 1, 1945

By R. Stauffer, S. Lindsay

"Sherritt Gordon Mines Limited utilizes pressure hydro-metallurgical techniques to recover nickel, copper and cobalt from su1phidic concentrates, mattes and various other metal-bearing materials.A brief description of the nickel refinery operation is given. In the nickel refinery process, an ammonia pressure leach is employed to treat the feed materials to dissolve the non-ferrous metals as their respective ammine complexes. The resulting leach solution goes through a series of steps which removes copper as copper sulphide and further purifies the solution prior to nickel precipitation by hydrogen reduction. The reduction end solution, containing the cobalt which was originally present in the leach solution as well as residual nickel, is treated with hydrogen sulphide. The resulting nickel-cobalt sulphide precipitate feeds the soluble cobaltic ammine process, which separates the nickel and cobalt and recovers the cobalt as a pure powder.A detailed description of the cobalt recovery process is given. Included are the various steps, comprising: acid leaching of the mixed sulphides, solution purification, ammine complex formation and cobaltous oxidation, two-stage nickel precipitation, cobalt conversion and reduction. A brief description of cobalt powder handling is included, along with typical physical properties and chemical analyses of the cobalt product. In general, the purpose of this paper is to describe the present plant practices employed in the recovery of cobalt as a by-product of the nickel refinery operations."

Jan 1, 1967

By S. F. Shaw

Tars paper is a review of the principal details of cyanide practice in several of the modern plants in America, mainly during the year 1908. Two of the mills, the Goldfield Consolidated and the Vets, Colorado, are not yet prepared to give data, the former having started about Jan. 1, 1909, and the latter not yet being completed. These two mills embody most of the latest methods and are therefore described as far as possible. I. CRUSHING. The principal methods of crushing ores for treatment by the cyanide process are with gyratory and jaw-crushers, stamps, Bryan and Huntington mills, and tube-mills. The first stage is usually done by gyratory or jaw-crushers, in a few cases sup-\

Jul 1, 1909

By Ray Brainard

Treated effluent from the Clean Water Coalition (CWC) member agencies is currently discharged at an annual average rate of 6,570 l/s into the Las Vegas Wash, and is increasing annually. As the effluent flow increases, the nutrient loading of the treated effluent will approach the maximum limits allowed under the current regulations. To manage this flow while maintaining water quality in Lake Mead, the CWC is implementing a 44-km-long conveyance system. This paper discusses the geological and geotechnical aspects of the 13.4-km-long tunneled section through the River Mountains and their effect on design. The tunnel alignment traverses a heterogeneous package of volcanic and sedimentary rocks exhibiting widely variable rock conditions.

Jan 1, 2008

Minerals are vital to any industrialized civilization. Annually, the United States uses more than 4 billion tons of new mineral materials, or about 40,000 pounds per person-about half being mineral fuels and the other half metals and nonmetallics. Stable and economic domestic mining, mineral, metal, and mineral reclamation industries are essential to the economy. The value of United States energy and processed materials of mineral origin exceeds $200 billion annually. Although a number of minerals are imported, especially some designated as "strategic and critical," most U.S. mineral supplies are derived from the domestic mines and processing facilities that you will be seeing, reading about, and visiting as you use this visitor guide. We hope you enjoy your experiences. This pamphlet, a guide to mining and mineral operations that may be observed or visited and some other points of interest relating to minerals, is intended to aid tourists and students who are interested in mining. Some may wish to study our Nation's romantic past; others may plan to enter the minerals industry as a career; still others may have a primary interest in conservation practices. The pamphlet is also intended to aid State and local officials, Chambers of Commerce, and mining firms in answering some of the many questions of tourists and students.

Jan 1, 1977

Mechanism Responsible for Flocculation in Poly (N-Isopropylacrylamide) Temperature Responsive Dewatering - Attractive Interaction Forces Induced by Surface Hydrophobicity

Sep 13, 2010

The placer mining industry of the West Coast region of the South Island is based largely around the production of alluvial gold, although other valuable minerals are also present. Since the first major discoveries in 1864-65, reported gold production has totalled around 264 t (8.5 Moz). During the past 10 years, annual production has totalled around 1460 kg (47,000 oz). It is anticipated that gold production over the next three years will continue at a level of 1400-1800 kg.   Annual gold production peaked during 1866 at approximately 17,170 kg (550,000 oz) and has not exceeded 100,000 oz since 1885. This reflects the ease with which gold was won from shallow, rich deposits that were present at many localities. Subsequently, there has been a general decline in the availability of this type of deposit, a trend that will continue in the future. This paper outlines the present state of placer mining in the West Coast region, gives some historical background to the industry and briefly predicts future trends.

Jan 1, 1997

By Frank van der Meer, Jorge Portocarrero, Alexandra Gruendken

"The number of High Pressure Grinding Rolls (“HPGRs”, also called Roller Press) installations instead of tertiary crushers is rapidly increasing. The technology has been largely accepted in the minerals industry and benefits, such as superior energy efficiency and a lower overall operating cost compared to alternative technologies, have been demonstrated at a number of operations throughout the world.This paper focuses on coarse hard ore operations and reviews the successful installation of the first Roller Press installed instead of a tertiary crusher at the Los Colorados Plant of CMH (Chile) in 1998. It details the experience obtained over the past ten years of operation from commissioning to the present day. It highlights examples of further developments made in the design to improve machine maintainability and availability as well as wear life of the grinding surfaces.A second focus lies on procedures to derive from small scale testing material properties such as wear life, flake formation and strength and their application to industrial size machines to optimize circuit design, especially when Roller Presses are used in closed circuit with screening.INTRODUCTIONRoller Presses (also known as HPGR, High Pressure Grinding Rolls) are considered today state of the art for the preparation of pellet feed. They are also gaining wide acceptance in coarse ore operations. One of the first successful operations in which a roller press was used to replace a conventional tertiary and quaternary crusher is the Los Colorados plant of CMH in Chile.When the Roller Press at Los Colorados was commissioned in 1988, there were 169 Humboldt Wedag roller presses in operation throughout the world. Of these, 14 were installed in the minerals industry. However, these were installed mainly for grinding pellet feed to increase the Blaine value. Up to that time, only three KHD roller presses had been applied for crushing coarse ore in specialized circuits. Moreover, the installation at Los Colorados was the first Roller Press ever to replace a conventional tertiary and quaternary crusher in a hard ore application."

Jan 1, 2009

By Turker L

The leaching of Tellness (Norway) ilmenite concentrate in hydrochloric acid and mixed aqueous HCl-alcohol solutions at boiling temperatures was investigated. It was found that the alcohols methanol, ethanol and ethylene glycol all substantially increased the leach rate and in the case of methanol and ethanol this was achieved at lower boiling temperatures compared with aqueous HC.

Jan 1, 1986

By K. Richardson

Although the De Beers group has a long history of placer mining on land, the group only became actively involved in deep water marine diamond exploration and mining in 1983 with the formation of DeBeers Marine. Full-scale commercial mining commenced around1991. Since then, the group marine mining capability has grown into a formidable fleet of 8 large deep water (>70 m) mining vessels, as well as other special purpose geosurvey platforms. Marine diamond production by the group is expected to be just short of 1 million carats in 2006. De Beers operates across the entire value-chain spectrum from geology and geosurvey, through sampling to mining, and finally ore processing into high value concentrate. Supporting these operations involves significant service activities such as maintenance, security, logistics and environmental management. Specific challenges exist in terms of developing or acquiring appropriate technology for marine mining. These challenges have resulted in De Beers operating extensive in-house R&D and projects departments, as well as drawing extensively from technology partners. An array of computational and test facilities is also available to support R&D and projects activities. Hydrotransport in various guises is key to the current approaches to marine mining and ore processing. Use is made of airlift and centrifugal pumping for hydraulic hoisting of very coarse gravel, while splitters, launders, dewatering, elutriators, jet pumps, centrifugal pumps, dense medium circuits, pipeline systems, and instrumentation for coarse abrasive particles are used extensively in the ore processing plant.

Jan 1, 2007