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By Keith L. Harris

The U.S. economy continued to grow moderately in the third quarter, but at a slightly higher rate than in the previous quarter. According to the Department of Commerce's preliminary estimate, real gross national product (GNP) grew at a seasonally adjusted annual rate of 3.3% during the third quarter of 1985, compared with a revised 1.9% for the second quarter and 1.6% for the third quarter of 1984 (table 1). Civilian unemployment dropped from the constant 7.3% rate between February and July to 7.0% in August and 7.1% in September. Employment on nonagricultural payrolls continued to increase (table 2), resulting in a continued rise in personal income, which in turn supported growing consumer purchases. Although purchases of services continued to provide the underlying foundation for the economic growth, the manufacturing sector received additional stimulus from significant increases in consumer purchases of durable goods, particularly automobiles. The increased demand for durable goods resulted in significantly higher industrial production for August and September, compared with levels attained previously this year (table 3). Capacity utilization increased to 80.5% in August but returned to 80.2% in September, matching the 1985 low previously reached in July (table 4). The real net export deficit grew only $0.2 billion in the third quarter; at $34.0 billion, however, it continued to exert a negative influence on the economy. On September 22, in an effort to reduce the deficit and make U.S. goods more competitive on world markets, the U.S. Government agreed to cooperate with the Governments of France, the Federal Republic of Germany, Japan, and the United Kingdom in attempting to lower the-value of the dollar in relation to other world currencies. Low inventories, rising factory orders and construction spending, the possibility of a lower U.S. dollar, and aggressive automobile production plans announced by domestic producers for the fourth quarter indicate the potential for an increase in manufacturing activity in the United States.

Jan 1, 1985

By D. Yu Pleev, V. G. Krivolapov

Mines of Southern Kuzbass working out, basically, coal formations of flat seams. Seams, as a rule, are inclined to self-ignition. Detection at early stages of the centers of endogenous underground fires has great value for safe conducting mountain works. One of methods of detection of an early stage of underground fires in the worked out space is the method of superficial radon survey. In the report the method is de-scribed and examples of superficial radon survey on concrete layers are given.

Jan 1, 2003

By S. R. B. Cooke, S. W. Clark

Adsorption of calcium and magnesium by quartz was determined over a wide pH range using flame photometry for solution analysis. A parallelism was noted between calcium adsorption at alkaline pH and flotation of activated quartz by means of various fatty acid collectors. Abstraction of calcium from 100 ppm solutions increased above pH 10.5 until all of the calcium was removed at pH values between 12 and 12.5. Calcium was desorbed from the quartz over the pH range 12.5 to 13.0 and returned to the solution. Precipitation of magnesium hydroxide prevented measurement of magnesium adsorption above a pH of 9.9. A calcium adsorption isotherm determined at pH 9 matched measurements of barium adsorption by other investigators over the range where adsorption corresponded to the equation of a Freundlich adsorption isotherm. In accordance with the Gouy-Chapman theory for adsorption in the diffuse layer, adsorption of the divalent cations under these conditions was four times the adsorption of monovalent sodium. Activation of quartz by multivalent metal cations in flotation using anionic collectors has been studied by many investigators. The occurrence of activator cations in the water of flotation mills makes depression of silaceous gangue very difficult. Alternatively, in some flotation systems it is practical to cause activation of quartz so that it is floated from the desirable mineral values. The present study was initiated to investigate the activation of quartz by measuring adsorption of calcium and magnesium ions as a function of solution pH. Early empirical tests showed that quartz would be activated to flotation using anionic collectors if any of a number of divalent or trivalent metallic cations were present in the pulp.1*2 Subsequent studies by Clemmer,3 Cooke and Digre,4 Cooke,5 Schuhmann and Prakash,6 and Cooke, Iwasaki, and Choi,7-8 showed that flotation depended strongly upon the alkalinity of the flotation pulp, the concentration of the activating cations, and the chain length and structure of the organic collectors used. The concept of the electrical double layer has been applied to the case of the quartz-aqueous solution interface by Gaudin and Fuerstenau,9-10 and by de Bruyn 11 to explain the activation of quartz by multivalent metal cations. Studies of the surface of quartz by Gaudin and Fuerstenau9,10,12 and by Li " using the streaming potential technique contributed much information on the electro kinetic condition of the surface of quartz in the presence of various organic and inorganic ions. Measurement of adsorption of ac-

Jan 1, 1969

By Ralph King

Blasting has been completed when the lawyer calls to say that a landowner has filed a suit alleging damages to the roof of his home. Mitigation talks fail to produce an adequate resolution and the case goes to court. The blaster has pictures of the area made after the blasting was done showing the good condition of the roof. However the judge fails to allow the photographs to be entered as evidence and the homeowner wins the case.

Jan 1, 2008

By Fritz Grübl

Modern shield TBMs allow tunnel drives through almost any type of ground. Thanks to high elaborated technical measures, significant subsidence of the ground surface can be almost entirely avoided. The tunnel lining behind the TBM must be capable of withstanding all loads without deforming, especially during ring erection and advance. Single-shell tunnel linings behind the TBM, usually reinforced concrete segmental rings, can be designed to fulfill this demand. With many projects, however, damage occurs to the lining. Repair costs may be extremely high. Reasons for damages and possibilities to avoid them are shown and explained.

Jan 1, 2001

By P. R. Scheller

Reactions between metal and slag are of decisive importance for metallurgical processing. In the continuous casting process, where metal solidifies at the metal-slag interface, reaction products can cause surface defects, with quality damages of the cast products as a consequence. These investigations are focused on the contact area between casting flux and metal. The samples were taken from the mould during the casting process. The results show that layers up to approximately 300 nm from the slag/metal interface represent a specific reaction space. Sodium in this layer on the slag side plays a specific role, which is explained on the basis of experimental results. The transport of oxygen near the interface and the charge transfer is explained on the basis of the ionic character of the slag. The mass transfer rate of oxygen crossing the interface is calculated from measured data, and conclusions concerning the stability of the interfacial tension are made. Keywords: mass exchange, metal slag reaction, interface, ion transport, oxygen transfer, oxidation, casting slag, flux, sodium

Jan 1, 2004

By None None

Use this month wisely — go online and take advantage of your new member benefit. As an SME member, you can read and download for free all of the full-text papers of the Mining, Metallurgy & Exploration (MME) journal, including the 22 papers in the launch Special Issue on Mineral and Metallurgical Processing in Honor of Professor Emeritus Douglas W. Fuerstenau as well as the archived articles of Minerals & Metallurgical Processing (MMP), all the way back to Vol. 1, No. 1. Just follow the instructions on this page.

By L. O. Howard

Much work has been done recently on the lead-antimony system' in connection with lead-rich alloys of commercial importance containing less than 20 per cent. antimony. Dean, Zickrick and Nix have called attention to the perpetuation in the literature of several erroneous data, such as a eutectic temperature of 228° C. at 12.5 per cent. antimony, instead of 247° at 13 per cent. The series is given as a classic example of a straight eutectiferous series in such late books as those of Heyn and Grossmann,2 Jeffries and Archer,3 Guillet and Portevin,4 Pulsifer,5 Rosenhain,6 and Liddell,7 as well as the somewhat earlier works of Hofman (1918), Wang (1909), and Williams (1920). The work of Dean has definitely shown a solid solution of antimony in lead at about 2.5 per cent. antimony. While lecturing to a class in general metallurgy at the University of Idaho, the writer had the students prepare a series of lead-antimony alloys for the purpose of illustrating methods of thermal analysis. Proper proportions of powdered antimony (sold as C.P.) and. test lead were mixed and melted in graphite crucibles under a reducing cover. Cooling

Jan 1, 1928

By P. G. Martin

"As the speed of business has continued to increase over the last decade, the focus on real-time control of the performance of both stationary and mobile assets has become an increasing priority. Traditionally the maintenance team has been focused on the management of the availability of assets while the operations team has been focused on the throughput of those same assets. Typically operations and maintenance teams worked almost independently in spite of the fact that they were both working with the same assets. Part of the problem has been their traditional performance measures which have often been diametrically opposed. Recent advancements in the area of real-time performance measures and decision support have helped to drive higher levels of collaboration between operations and maintenance leading to real-time asset performance control and higher levels of business performance. This paper will explore the forces driving the need for changes, present an effective approach to the definition of the most appropriate business performance measures, and examine the effectiveness of contextualized real-time decision support resulting in asset performance control. TRADITIONAL APPROACHES TO ASSET PERFORMANCE MANAGEMENT In most industrial operations the phrase asset performance management is synonymous with maintenance of the industrial assets. This is the way industry has viewed asset management and asset performance management for decades. This is a very limited perspective that is serving to constrain the profitability of industrial operations. As industrial organizations began to form following the Industrial Revolution, the complexity of the operations forced an organizational design based on specialization. No single person could understand all of the aspects of an industrialized operation. This was particularly true at the plant floor level where the operation and maintenance of the industrial equipment required very different skillsets and training. To accommodate the vast differences most industrial organizations set up operations teams to run the equipment and maintenance teams to keep the equipment available to the operation. Both teams were dealing with the same industrial equipment but from very different perspectives and with very different performance measures. Typically the operations team was measured on maximizing the output of the equipment – or throughput. On the other hand the maintenance team was measured on the uptime – or availability of the equipment."

Jan 1, 2015

By C. D. K. Gauert

High-pressure waterjet technology is proposed as an alternative tool for selective underground mining of high-grade ore sections in stratiform orebodies showing a preferred ?bottom? or ?top? enrichment such as the Witwatersrand reefs and the Bushveld Complex platiniferous reefs. This technique, utilizing known mining technology together with more advanced machinery and additives as used in industrial and cleaning applications, may lead to an increased life-of-mine (LOM) for mining operations. A series of experiments was successfully carried out in a laboratory on Witwatersrand quartzite material, indicating acceptable cutting performance. Mining volumes by selectively cutting of reef portions are considered to be comparable to traditional drilling and blasting. Economic advantages of waterjet mining include energy savings due to the lower quantity of gangue rock to be hoisted to surface, as well as savings by a decrease in the usage of blasting materials. Capital expenditure of waterjet cutting, if applied on a broad scale, could be lower in the long term than that of conventional drilling and blasting methods. Mining by the application of high-pressure waterjet technology could become a competitive ?green technology? improving the economics and safety of labour-intensive mining operations. This paper suggests that waterjet cutting at an industrial scale can become a routine hard-rock mining technique in the future. Keywords waterjet cutting, high pressure, mechanized narrow reef mining, abrasive agents, costs, selective mining.

Jan 1, 2013

By D Reid, J Black

The adverse health impacts from diesel particulate matter (DPM) exposure are a well-known global concern. The building evidence has triggered underground mining operations to review existing atmospheric conditions and assess the scale of the challenge faced. South32’s Cannington Mine (Cannington) evaluated the ability to provide a healthy atmosphere from a whole mine approach, taking into account existing preventative controls including: maintenance strategies, fuel quality, mining operations, ventilation provisions, monitoring protocols and effective education and training programs.During the evaluation process, Cannington gave due recognition to the advice and guidance provided in the Queensland Guidance Note 21 (QGN21), the Guidelines of New South Wales’ MDG29 and Mining Industry Advisory Committee (MIAC) of Western Australia. Each of these documents advises a dilution rate of >0.06 m3/s/kW is best for reduction of DPM exposure in underground mines.Achieving the prescribed mine ventilation rate typically results in the need to directly invest significant capital into increasing ventilation infrastructure in order to further dilute contaminants. In today’s economic market of volatile metal prices and increasing pressures to meet regulatory requirements, it can become challenging for established metalliferous operations to create a balance between optimisation of current ventilation infrastructure and capital outlay.In order to obtain and correctly justify the requirements for capital investiture Cannington conducted a ventilation operational analysis for the life-of-operation, identifying the existing air volume envelope was adequate for current and future production rates by optimising existing primary ventilation infrastructure through the implementation of a modified ventilation on demand (VoD) and air conservation system.This process achieved sustainable operating and capital cost reductions without compromising delivery of adequate ventilation to work areas. The process also recognised that engaging mine workers’ ownership of their work areas is crucial to maintaining a technically efficient and operationally robust ventilation system.This paper will concentrate on Cannington’s existing preventative controls, their implementation and their management for the prevention of increased DPM exposure; reducing the risk of both short and long-term health impacts to ‘as low as reasonably achievable’ (ALARA).CITATION:Black, J and Reid, D, 2017. Delivering a healthy atmosphere underground in a cost-conscious environment, in Proceedings Australian Mine Vent Conference 2017, pp 159–168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By G R. Ballantyne, M S. Powell

A comprehensive Australia-wide survey of comminution energy consumption at copper and gold mines was presented by the authors at the 11th AusIMM Mill Operators’ Conference 2012. The database has been extended to include major overseas mines and used to benchmark comminution energy consumption across the industry. The mines included in this study now represent 15 and 24 per cent of the total global gold and copper production respectively, and almost all Australian production. The comminution energy intensity per unit of saleable metal has been presented in a graphical form similar to a cost curve used in economics. The graphical method has been developed to assess the competitive advantage that can be achieved by reducing comminution energy intensity.This benchmarking tool has been applied to three published case studies to assess its applicability. The first case study indicated that a large reduction in size-specific energy (kWh/t -75 µm) was achievable by converting standard semi-autogenous and ball mill circuits to include high pressure grinding roll and stirred mills. The second case study investigated the metal-specific energy reduction historically achieved by Bougainville with the addition of a preconcentration screening plant. The final case study was conducted by Barrick Gold Corporation and involved incremental efficiency upgrades at three of its gold mines: Cortez, Cowal and Mara North. The application of the benchmarking tool to each of these case studies successfully demonstrated the scale and competitive advantage that was achieved by reducing energy intensity.CITATION:Ballantyne, G R and Powell, M S, 2014. Benchmarking comminution energy consumption for improved efficiency, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 95–100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Arnulf Muan, R. W. Taylor

Activities of iron in Fe-Pt alloys have been dctermined by equilibrating mixtures of platinum metal and iron oxide at known oxygen Pressures in a thermobalance at 1300°C. Conzpositions and iron activities of the oxide phase at equilibrium are known from previous work, and compositions of the Fe-Pt alloy phase formed at equilibrium were detcvt?zined from the observed weight changes of the samples. The activity curve obtained shows a strow negative deviation from Raoult's law. THE present investigation was undertaken as part of a research program dealing with phase equilibrium relations existing among the oxides of iron and titanium at 1300°C. At low oxygen pressures of the gas phase in equilibrium with these oxides, the iron activity of the system is high, and considerable alloying of iron with the platinum used as a container material takes place. Thermodynamic data for Fe-Pt alloys at 1300°C are needed in order to evaluate quantitatively the extent of such reactions. Larson and chipmanlhave determined activities of iron in Fe-Pt alloys at 1550°C by equilibrating platinum metal with CaO-iron oxide-SiOzmelts in which the iron activities were known. Compositions of the resulting Fe-Pt alloys were determined by chemical analysis. Mundiath and Gerassimov2 have studied thermodynamic properties of Fe-Pt alloys by electromotive force measurements in the temperature range 550" to 1000°C. The experimental method used in the present investigation is a slight modification of that used by Grube and Ratsch3 in studies of NiCr-alloys. 1) EXPERIMENTAL METHOD 1) General. Mixtures of platinum metal and iron oxide were equilibrated at 1300°C in atmospheres of known oxygzn przssures, and the course of the reactions was followed by measuring the weight changes of the mixtures. The principles involved in the derivation of composition-activity relations from these measurements are illustrated by the composition triangle for the system Fe-FeZO3-Pt shown in Fig. 1. Take as an example a mixture of FeZO3 (hematite) and platinum such that the total composition is represented by point T. If this mixture is heated to 1300c in air (poz = 0.21 atm) and the oxygen pressure is then reduced gradually, the oxygen content of the oxide phase decreases and increasing amounts of iron enter the metal phase. As the oxide phase and the metal phase for all practical purposes are insoluble in each other, their compositions are represented by points moving toward Fe along the joins Fe-Fe,03 and Fe-Pt, respectively. The total composition of the mixture during this process also changes, but only with respect to oxygen content, because the vapor pressures of iron and platinum are negligible at 1300°C. Hence the change in total composition is described by a straight line (constant Fe/Pt ratio) radiating from the 0 apex of the composition triangle Fe-Pt-0, of which the triangle in Fig. 1 is a part. Only one such line ("oxygen reaction line", T-T",) is shown in Fig. 1. The total composition of the alloy-iron oxide mixture at any instant must, in addition, be located on the straight line (conjugation line) connecting the two points representing the compositions of the two coexisting phases. It therefore follows that the total composition of the mixture at any instant is represented by the point of intersection between the conjugation line and the oxygen reaction line. An example of the situation prevailing at a chosen oxygen pressure, po2, is shown in Fig. 1 by points a' (alloy composition), b' (oxide composition) and T' (total composition). Point b' is known from the work of Darken and Gurry,4 and point T' is experimentally determined by the observed weight change of the mixture (distance T-T). Hence, point a', the composition of the alloy, is determined from the above data as the intersection between the join Pt-Fe and the extension of the straight line bl-7'. The activity of iron in the alloy at equilibrium is identical to that of the iron oxide phase, if the same

Jan 1, 1962

By Steven I. Majtenyi

There is a growing interest among transportation planners to make more use of the subsurface to preserve the landscape and make transportation more efficient and economical. At the present time, utilization of the underground for transportation facilities is severely restrained by the adverse environmental impact and high construction costs. However, recent studies performed by the United States Department of Transportation indicate that, in spite of such problems, the volume of underground construction has significantly increased during recent years and projections point to continuation of these trends(1). It is estimated that the total volume of transportation tunnel construction will exceed $4 billion in this decade. This level of Investment justifies a significant research program. Due to the common interest in transportation tunnels and to the similarities of problems encountered during their construction, the tunneling research activities of the Federal Highway Administration (FHWA) are closely coordinated with the programs other agencies of the U. S. Department of Transportation DOT); specifically, the Federal Railroad Administration (PRA) and the Urban mass Transportation Administration (UMTA). The FHWA is responsive to the particular needs of these agencies but will benefit from the research results obtained also. In 1971, the Office of Secretary, DOT, initiated plans for an overall coordination of the DOT, FICA, UMTA, and FHWA tunneling research activities. The objectives of this effort have been to reduce tunneling costs by 30% and to increase the rate of excavation by 200% within 10 years. This coordinated program was developed and promoted during 1972 and 1973 by Dr. Eugene L. Foster, at that

Jan 1, 1974

By John C. Balla

The Spar Lake deposit is located in northwestern Montana, approximately 27 km (17 miles) south of Troy, MT, under Mt. Vernon. The deposit is a stratiform, stratabound copper-silver deposit occurring in the Revett Formation of the Proterozoic Belt Supergroup. Distribution of known sandstone-type deposits in the Revett Formation is shown in Fig. 1.

Jan 1, 1991

By J. B. Newsom

In the Indiana limestone district, some 50 or 60 per cent of the merchantable stone in a quarry opening is waste, and only about 40 or 50 per cent of the stone from the opening is finally sold. So long as the present system of 'quarrying is used, the wastes measured and reported in this paper will continue. Comprehensive development of an entirely different method of quarrying, using wire saws for cutting, promises great improvement. Some of the savings to be expected are pointed out in the following pages. No attempt has been made to measure losses due to variations and natural flaws in the stone, since these vary greatly in different quarries, and accurate measurement would be difficult. The wastes that have been measured account for about 30 per cent of the total ledge, which leaves 20 or 30 per cent chargeable to unmeasured sources of loss. General Causes of Waste There are four general reasons for quarry waste: (1) the structure of the deposit, such as its shape, bedding planes, solution cavities and strain fractures; (2) efforts to quarry blocks which do not contain distinct color or textural variations; (3) the trade custom which permits purchasers to specify the size of the quarry blocks which they will buy, which is a matter of competition for business on the part of stone producers; (4) quarry methods, which cause the greatest amount of waste. Wide channeler cuts, hook holes, crooked splitting and uneven breaking on quarry floors are included in this category. Waste Due to Structure of Deposits The peculiarities of structure cannot be eliminated, but a chance for saving lies in quarrying to take advantage of them. The commercial deposits of Indiana limestone are lenticular masses from 20 to 70 ft. thick, and nearly horizontal. All of these deposits of good stone are in the Salem limestone, a bed in the sub-Carboniferous. The Salem is traversed by two systems of vertical fractures, a major system running from northeast to southwest and a minor system running from northwest to southeast. Where the stone is covered by an over-

Jan 1, 1932

By P. C. Good

High-purity chromium was prepared in massive form by the electrolysis of chromium trioxide solution at high temperatures. The metal thus obtained, containing 50 to 150 p.p.m. of oxygen, 20 p.p.m. of nitrogen, and traces of metallic impurities, could be hot-worked to rod and sheet and drawn to wire ductile at room temperatures. Optimum concentrations and operating conditions were established for the deposition of chromium from chromic acid baths containing sulfate, fluoride, and silicofluoride ions. Current efficiencies of 13 percent were attained with baths containing sulfate ion, and efficiencies of 40 to 44 percent with baths containing fluoride and silicofluoride ions. Cation exchange resins were used for removing metallic impurities from chromic acid solutions containing sulfate ion; solutions containing fluoride and silicofluoride ions were purified by recrystallization.

Jan 1, 1960

By Gaspard Devos

1. A NEW CONTEXT FOR METAL INDUSTRY Producers and owners of industrial extractive sites are living hard times due to Environmental pressure and liabilities. This is valid whatever the region in the world, it is just a question of time. On one hand, the normative environmental pressure is increasing through more severe regulations and controls on all pollution sources and production materials. [ ] Furthermore, more impurities are extracted and captured, more the volume of the related wastes is increasing. But disposal costs are increasing, disposal areas for wastes are restricted, markets for wastes are limited and technologies for waste treatment are, most of the time, not available. On the other hand, for most of the extractive industries, the costs required to get access to refine primary raw material are killing the profitability of the industry. Definitively, a technological and economical breakthrough is ongoing: extractive industries have to increase their feed from secondary material and to be involved more and more with the recycling business.

Jan 1, 2005

By B. Yu, N. Verbaan, A. Mezei

The recent 20 years witnessed a boom and bust in the nickel laterite industry. Most notoriously is the story of the first three Western Australian nickel laterite projects which all suffered major ramp-up issues. Many hard lessons were learned by the industry and it has been widely reported that the major contributing factors included insufficient testing as well as a limited understanding of the materials handling characteristics at the front-end stage of the flowsheet. This paper compares the current "race to production" in the REE industry to the laterite industry 20 years ago and addresses the fundamental question: ‘Have mining and exploration companies with rare earth projects learned from past lessons and are they doing sufficient and appropriate testwork to prevent failure’? The authors will provide the perspective of a commercial metallurgical laboratory that has gone through the laterite cycle and is active in the present REE cycle.

Jan 1, 2014

By William Hustrulid

The National Institute for Occupational Safety and Health (NIOSH), as part of a comprehensive program to improve mine safety through the widespread acceptance of careful excavation principles in drifting, have revisited standard drift round design concepts. Although the initial emphasis was on contour row design and providing improved design tools for blasting with de-coupled charges, the focus has broadened into the development of a general gas pressure-based drift round design approach. The concept of a damage radius (Rd) for a given explosive-hole-rock mass combination is introduced. With the damage radius as the basic building block, the blast holes are positioned on the face, beginning with the buffer row, to achieve the desired excavation size, shape and smoothness. The design of the contour row of holes is also performed using a pressure-based approach. The paper presents in some detail the overall approach and the required gas pressure-based design equations.

Jan 1, 2007