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By P. F. Patterson

It is a well established fact that 60 per cent of all accidents in coal mines occur from falls of roof and coal at or in the proximity of the working face. Notwithstanding that this is well known, and has been frequently discussed by mining men, this seems to be the irreducible minimum. It is even said by those in a position to know that the percentage stated is increasing. With this, information before us it would seem that not enough attention is being given to close supervision at the working face, and until this is done we may expect to continue experiencing an increase in the accidents in this area. No workman generally feels that it is more important to finish loading a car of coal than to set a timber for protection, and many accidents happen from this source, not from a lack of knowledge of the dangerous conditions existing, but negligence in taking remedies necessary to remove the danger. It is true that nearly all state laws require the mine foreman or his assistant to visit each working face every day, but with the constantly changing conditions on account of the advance of the working faces, these daily visits may be entirely inadequate to discover possible dangers and prevent accidents. The obvious remedy then is closer and more systematic inspection and supervision of the working faces. Many accidents are caused in mines on account of not enough clearance between the rib and track or between timber and track. On all main haulage ways. there should be a space of at least 30 inches between the rib and track, or timber and track, and on all rooms not less than two feet should be left between the track and upright timbers.. A great deal has been said and written with regard to systematic timbering. We doubt very much the feasibility of adopting any standard of timbering that would be suitable for all roof conditions, and any such system in our opinion would not tend to cause a decrease in the number of accidents. The proper place to put up a prop, regardless of whether it conforms to any established system, is under a piece of loose roof. No habit is becoming more prevalent among miners and other mine workers than wearing gloves, principally flimsy canvas gloves, which afford no protection to the wearers and are the direct cause of many hand injuries. If gloves must be worn, and no doubt they will be as the habit has become well established, then they should be made from some heavy material and should fit the hands fairly snug.

Jan 1, 1923

By A. H. Winckers

"CAMIRO, The Canadian Mining Industry Research Organization, formerly known as MITEC, is a collaborative research organization of Canadian Mining Companies. It is comprised of Exploration, Metallurgical Processing and Mining Divisions.The Metallurgical Processing Division (MPD) has the mandate to contribute to the profitability, competitiveness, safety and growth of the Canadian mining industry by improving the efficiency and effectiveness of mineral processing and extractive metallurgy in an environmentally conscious manner through the development of innovative technology by managing cooperative industry focused research programs.Current membership includes about ten Canadian mining companies. Past research has largely focused on base metal mineral processing. The Division wants to expand its research base to include all areas of mineral processing and extractive metallurgy.Past performance and plans for the future will be highlighted in the presentation."

Jan 1, 1998

By J. D. Davis

THE CARBONIZING properties of Chilton-bed coal from Lorado No. 5 mine, HE Logan County, W. Va., were determined by Bureau of Mines-American Gas Association tests at 600°, 700°, 800°, 900°, and 1,000° C. and by expansion tests. Chemical analyses, agglutinating and plasticity tests, and low- and high-temperature assays also were included in the investigation. Blends with low-volatile Pocahontas No. 3 coal were carbonized at. 900° C. The Chilton coal bed lies in the Kanawha, or Upper Pottsville formation of the Pennsylvanian system; the estimated original reserves are nearly 3.2 billion tons. The bed was 39/1 to 57 inches thick in the Lorado No. 5 mine, and the coal was 38 to 57 inches thick. The carbonization sample contained 62.6 percent fixed carbon on the dry, mineral-matter-free, basis, and the heating value on the moist, mineral-matter-free basis was 15,190 B. t. u. per pound; it therefore ranks as high-volatile A bituminous. It contained 1.8 percent moisture, 35.2 percent volatile matter, 57.9 percent fixed carbon, 5.1 percent ash, and 0.7 percent sulfur, as carbonized. The sulfur was largely organic, and the ash softened at 2,630° F. The agglutinating value determined on a silicon carbide-coal mixture of 15:1 was 6.8. In the Gieseler test the coal softened at 327° C., fused at 407° C., attained a maximum fluidity of 5,730 dial divisions per minute at 435° C., and solidified at 487° C. Maximum resistance in the Davis plastometer was 45.5 pound-inches.

Jan 1, 1951

By H. H. Waller, C. H. Brehaut

At the Jeffrey mine of Canadian Johns-Manville Co. in Asbestos, Que., automatic batched concrete from surface is placed underground pneumatically for distances of 2500 ft directly into forms or to a second placer for greater distances, through 6-in. pipe of high carbon steel. The use of Celite C-4-C in addition to the usual aggregates achieves greater compressive strengths, lowers cost, reduces segregation, and improves workability and placeability results. Each year 25,000 cu yd of concrete are placed without interrupting production and development work in the mine, making possible a cheaper concrete that can be poured wherever and whenever it is needed. In about 90 pct of the underground openings in the Jeffrey mine concrete is necessary to preserve them in their original sizes and shapes for production. In the remaining 5 pct, the greater portion is united with or without steel support. When large quantities of concrete were forecast for underground use at the Jeffrey mine, preliminary and first hand information regarding pneumatic placing was acquired from articles by Bernhardt and Swanson and visits to their respective mines.

Apr 1, 1956

By Brent K. Nelson, D. Lee Petersen, Charles R. Nelson

INTRODUCTION Tunnels are commonly constructed in the very weak St. Peter sandstone in the Twin Cities area of Minnesota. Historically, core recovery in this weak sandstone was very small in the critical weaker strata resulting in little preconstruction information on the ground conditions. Improved core recovery techniques have been utilized for recent projects, allowing rock quality rating methods to be developed for the recovered core. Down-the-hole tests, and the use of combination ratings between different types of core data provide for more detailed characterization of ground conditions. THE ST. PETER SANDSTONE The 45 m thick St. Peter is an unusually pure quartz sandstone. It underlies all the Twin Cities area, except where it has been eroded by the present day Mississippi River or by pre-glacial rivers. It forms conspicuous steep bluffs along the Mississippi River where the upper Platteville limestone formation protects it from erosion. Where the Platteville formation is missing, the sandstone slopes are often more gentle. Natural case hardening of the exposed sandstone bluffs often forms a resistant crust and reduces sloughing. This case-hardened surface is not representative of the sandstone back from the bluff.

Jan 1, 1987

By Shouchen Dun, Zong-Ming Li

Manipulation of hand-held objects in 3D space is a complex task. Understanding how individual digits interact with a hand-held object provides helpful information for hand tool designers, researchers, clinicians, and occupational therapists. At the object-digit interface, the contact mechanics can be represented by three force and three torque components. Six-component force/torque transducers can register all the three forces and three torques at the digit-object interface, and therefore are advantageous in the study of manipulation mechanics. The large number of force and torque signals from multiple force/torque transducers are difficult to interpret and therefore making experimental research of manipulation a challenging task. The purpose of this study was to develop a 3D visualization tool for the investigation of the contact mechanics at the object-digit interfaces during manipulation tasks. Methods A 3D stick-figure hand model was created based on digitized 23 anatomical landmarks of the hand. Five miniature 6-component force/torque transducers (4 × Nano17 for the fingers, 1 × Mini40 for the thumb, ATI Industrial Automation, NC) were used to record force and torque data at the tips of individual digits. Thirty channels of force/torque signals from the transducers were collected by a 16-bit analogue-digital converter (PCI-6031, National Instrument, Austin, TX) installed in a computer. The transducers were mounted on a custom-made rectangular aluminum handle for object manipulation. Coordinate frames were established at each transducer, on the handle, and at the base of the MicroScribe digitizer. To visualize the force vectors at the digit-tips, the coordinates of the hand landmarks in the MicroScribe coordinate frame and the force vectors in local transducer coordinate frames were transformed to a common coordinate frame defined on the handle. One healthy right-handed, male subject participated in the experimental study. During the tests, the participant sat in a chair by a testing table. The forearm was strapped to an arm holder in neutral rotation position. The instrumented handle was fixed on the testing table by a C-clamp through an adapting plate. With the hand of the subject gripped on the instrumental handle, the landmarks of the instrumented handle and the transducers, as well as the anatomical landmarks of the hand were digitized using the MicroScribe digitizer for the purpose of coordinate frame establishment and transformation as described above. The subject performed three different maximum isometric voluntary contraction tasks: (1) grasping, (2) rotating in pronation, and (3) lifting. Results The 3D hand model and representative force vector clusters in a single trial of grasping, rotating, and lifting tasks are shown in Figure 1. Each cluster was formed by displaying all the 3D force vectors during the period of “stabilized” maximum effort in a trial. The magnitude and

Jan 6, 2006

By Charles L. Kimbell

The year 1977 generally was a year of growth in overall world mineral industry activity, although there were downturns in major elements of the world's iron and steel industries. The sharp upturns in market economy nation activities that were noted in 1976, following the reduced performance levels of 1975, were moderated, and in the centrally planned economy nations, overall mineral industry activity apparently continued to increase, but at a pace in keeping with that of 1916 rather than at the higher rates of the earlier 1976's. Noteworthy during the year, if only in a negative sense, was the inability of world powers to reach any significant agreement on issues relating to deep seabed mining. Interest from a commercial viewpoint centered around deposits or so-called manganese nodules. These materials, which indeed are chiefly manganese in terms of their content on a quantitative basis, really were of commercial interest primarily far their copper, nickel, and cobalt content. Participants at the Third United Nations Law of the Sea Conference looked into seabed mining rights, but reached no mutually agreeable decisions.

Jan 1, 1981

By John Jermain Porter

(San Francisco Meeting, October, 1911.) THE value of any particular ore, coke, or limestone, for iron-making, depends upon its effect, first, upon the quality or value of the resultant product; and second, upon the cost of smelting. The factors under the first head are the percentages of phosphorus, manganese, and other elements, which remain in the pig-iron ; while those under the second head are the percentages of iron, carbon, or lime, the slag-forming constituents, which must be fluxed, and any other ingredients which give rise to variations in cost of fuel and flux. The first of these criteria of value is perhaps not capable of being reduced to a general formula embracing all cases, since it must vary to a great extent with market-fluctuations. For example, Bessemer pig is worth sometimes more and sometimes less than foundry-pig ; and the premium paid for high manganese varies within wide limits. The second, or smelting-value, however, can be expressed numerically with a fair degree of accuracy; and it is with this phase of valuation that the present paper is concerned. The utility of a means of comparing numerically the relative smelting-values of different ores, cokes, and limestones, is self-evident, although it may not have importance in Northern practice, where materials are largely standardized. On the other hand, there are, especially in the South, many furnace-managers who must use a great variety of materials of widely varying grade; and it is with special reference to this district, and in connection with the efficiency-methods which I have elsewhere proposed,1 that the methods herein described were devised.

Mar 1, 1912

By Kai Wang, Chao Xu, Qiang Fu, Tong Yang, Chunyu Zhao, Wei Zhao

The stress of a coal seam is an important factor that affects the permeability of the coal seam and then affects the coalbed methane (CBM) drainage. In China, adjacent coal seam mining is an important method to reduce stress, which increases the permeability of the coal seam. However, in the process of mining adjacent coal seams, many coal pillars remain, which causes stress concentrations and results in a decrease in permeability. Therefore, it is important to study the influence of coal pillars on the stress of adjacent layers and its distribution and evolution in the floor rock. This paper took the Shendong Baode Coal Mine as a case study and investigated the influence of the coal pillar on the stress and permeability of coal seam #11. The results show that under a coal pillar, the relationship between the vertical stress of different floor depths and the width of the coal pillar can be divided into a negative correlation zone, transition zone, and positive correlation zone. The change in the coal pillar width does not affect the pressure relief range or the degree of pressure relief in the adjacent coal seams below the goaf. The field measurements show that after the mining of panel #81,505, the permeability coefficient of coal seam #11 under the goaf increased from 0.1434 to 26.3545 m2/( MPa2*d), increasing 182.7 times, and the drainage mixing volume of boreholes #1 and #2 increased from 1.24 to 1.52 m3/ min. While the permeability coefficient of coal seam #11 from 12.5 m in the coal pillar has only increased by 2.6 times, the drainage volume of boreholes #3 and #4 did not change significantly.

Nov 19, 2022

By F. Habashi

Brazil is a major mineral and metal producer, has magnificent fauna and flora, and superb architecture. In 1693 gold was discovered in Ouro Preto and Brazil produced about half of the world's gold. In 1726 diamond was discovered in the region of Tijuco in the Province of Minas Gerais, 150 km east of Bello Horizonte. The country became independence from Portugal in 1822 as the Brazilian Empire. In 1876, an Englishman succeeded in obtaining from the Amazon region seeds of rubber trees and secretly transferred them to England, where they were planted in the royal gardens at Kew. Some of the seedlings which spouted were sent to Ceylon and Singapore. Thus, began the rubber industry in the East. Today, Brazil is the largest producer of niobium, and produces a large number of other metals. The Mineral Research Center in Rio de Janeiro is the countries main Government establishment for mineral research. The country has been a republic since 1889 with its capital in Brazilia.

Jan 1, 2009

By W. G. Sandell, G. M. Potter

"As a part of the wartime activities of the Bureau of Mines, metallurgical services were extended to other Government agencies engaged in purchasing and stock-piling some of the more critical and strategic materirals. At the request of George A. Easley, representative of the MetalsReserve Company, beneficiation studies were made on a sample of complex tin-tungsten ore from the Urania mine in Bolivia, South America.The low-grade Urania ore (1.9 percent Sn and 1.55 percent W03) contained a very complex of cassiterite and scheelite with iron sulfidesand quartz. The problem involved in concentrating this ore was the removal of sulfides and silica by stage flotation and gravity concentration for the production of a marketable tin-tungsten concentrate. The sulfides and primary quartzite were readily rejected, but the secondary quartz was intimately associated with cassiterite, and ultimate recovery depended on treatment of minus 560-mesh (theoretical) sizes.The ore was amenable to concentration by ore dressing. Seventy percent of the tin and 83 percent of the tungsten were recovered in a product that assayed approximately 20 percent Sn and 20 percent W03 and that met grade ""F"" specifications of the Metals Reserve Company for mixed tin-tungston concentrates."

Feb 1, 1948

By R. F. Favreau, Patrice Favreau

"Ever since we have started to assist those responsible for blasting with blast simulation studies, we havebecome aware of an interesting aspect, namely that in 90 % of cases we are asked ‘‘Can you seek ablasting method which gives better fragmentation than the method which we use now’’. But after a visit to the site, and the evaluation of the fragmentation obtained with their present blasting method, it very often becomes evident that it is the ease of mucking and not the fragmentation which requires improvement. Hence we then proceed to do a simulation study the results of which are improved mucking rather then more fragmentation, and those responsible for the blasting always become very satisfied."

Jan 1, 2017

By A. Adu-Acheampong

Photogrammetry and laser scanning has been employed at a number of Newmont mine sites to mitigate risks associated with conventional structural mapping, determining the geometry of voids from old underground workings, and generating topography in areas of slope instability. Laser scanning has also been used to evaluate as-built pit slope configurations with respect to design assumptions, operational practices, and rock fall potential. Recently, remote sensing applications carried on an unmanned aerial vehicle (UAV) were used to generate base topography at some Newmont sites. UAV are generally more convenient and less expensive and can be utilized in areas where cloud cover prevents manned aerial photography missions. This paper discusses these applications, and provides commentary on their benefits and limitations based on recent experience.

Feb 27, 2013

By Kenneth L. Bickel

During an underground mine fire, the importance of controlling the spread of smoke and toxic gases with suitable ventilation structures has been proven. However, under certain conditions, control of the propagation of the fire itself may be even more critical in insuring a safe mine evacuation. Fire doors offer the means for accomplishing both objectives. In 1978, the Bureau of Mines initiated research to evaluate the state of fire-door technology and develop and test a fire door suitable for large openings (10 by 12 ft or larger) in noncoal underground mines. This report discusses current fire-door technology in the context of the underground mine environment and the design, fabrication, lab testing, and in-mine field testing of a mineworthy fire door. This door has a 1.5-h fire resistance rating and limits temperature rise across the door to 2500 F during the first 30 min of fire exposure.

Jan 1, 1987

By Stephan K. Schwank

In mid 1993, Bauer Spezialtiefbau GmbH, based in Germany got the order to develop a sampling tool capable of penetrating all different types of seabed sediments including cobbles and boulders and into bedrock. BHP and their partners Benguela Concessions Ltd., had been convinced by the Bauer Trench Cutter Technology and a large scale test in Germany that this system will be the right one to fulfill their expectations for sampling the diamond area off the coast of Namibia. The technique of the tool is based on Bauer's standard cutter technology, which is widely used for the installation of cut-off and diaphragm walls all around the world. The two counterrotating cutter wheels with 12.1 tom torque each cut an area of 3 x 1.2 m (up to 3 x 3 m are possible). The material mixed with seawater was then pumped to the separation plant on board the vessel Geomaster with a capacity of approximately 700 m3/h. Cutter wheels and mud pump were mounted on a special cutter frame and connected by wire ropes and hydraulic hoses to the vessel. An outer frame with four telescopic legs supported the cutter vertically on the uneven seabed and allowed a controlled penetration of the tool up to 6 m into the diamond bearing ground. The tool required a total power installed of approximately 800 kW. All hoses, the 6-inch mud hoses as well as the hydraulic hoses, were stored and compensated on drums on board suitable for a water depth of up to 200 m. Launch and recovery of the tool was effected through the moon pool of the vessel and the 25 m high, special designed drill tower. The 65? to sampling tool had been commissioned in early 1994 in Cape Town. After intensive testing the sampling programme of more than 4000 holes could be successfully completed by January 1995.

Jan 1, 1998

By João Carmo Vendramim

A oxidação da superfície de peças, ferramentas, moldes ou matrizes construídas em ligas ferrosas tem larga utilização na indústria. As aplicações podem ser as mais diversas, tais como simplesmente atender às questões estéticas, proteção da superfície contra a corrosão, ou proteção contra a interação química com outros metais. Dentre as técnicas industriais utilizadas há o processo conhecido como “Oxidação Negra” que é realizado em baixas temperaturas, com imersão do aço da peça em óleo quente, ou banho de sal especial, ou mesmo a frio (soluções especiais). Outros processos utilizam fornos industriais com atmosfera de ar para aquecer a liga ferrosa até temperaturas da ordem de 500ºC e acrescentar (“pingar”) água como fonte de oxigênio. E em outros, aplicação ceras hidrocarbonetadas e ácidos inorgânicos e posterior oxidação [1] com aquecimento a temperaturas da ordem de 500ºC. Nesses processos, o objetivo é formar uma camada de óxidos tipos Magnetita e Hematita cujas características de menor coeficiente de atrito e determinadas propriedades físicas e químicas serviriam de barreira à interação química com outros metais em contato. A camada de óxido obtida nas condições descritas acima é bastante útil para determinadas aplicações industriais, tais como moldes de injeção de alumínio. Esse texto descreve o processo de oxidação desenvolvido utilizando a tecnologia de plasma.

Jul 30, 2018

The energy supply in the 21st century is still secured by coal. According to estimates of the International Energy Agency (IEA), coal will have the same importance as oil for the world-wide supply of energy until 2030. Coal is also an important element of EU policy, its future use is closely linked to effectively addressing the environmental challenges it poses. Hard and brown coal represent approximately 80 per cent of European Union (EU) reserves of fossil fuels and coal utilisation can co-exist with the development of power generation based on renewables. Europe is the world's third largest consumer of coal behind China and the United States.The Czech Republic is poor in energy resources except for coal. Brown coal is relatively abundant (mineable reserves estimated at 1800 Mt, output 48 Mt/a) and significant quantities of hard coal (mineable reserves 900 Mt, 13 Mt/a), much of it suitable for coke production, are also present.Severoceske Doly (SD Company), the biggest Czech coal mining company (22 Mt/a, 48.6 per cent Czech market share) and one of the biggest in Europe, reinforces despite the last deep crisis in the Czech and European economies its long-standing stable and strong market and financial position. From 2009, the SD Company co-owns, with partners, a brown-coal mining company MIBRAG (21 Mt/a). SD Company invests in large mining equipment (eg new giant spreaders and bucket-wheel excavators, extension of overland belt conveyors), rebuilds and upgrades mining and processing installations, auxiliary and other machinery. We should see the investment we make today in tomorrow's mining and reclamation as an opportunity and not as a burden. They enable to make our position more resistant in the longer term. Projects focused on the environment and operational safety went hand in hand with these efforts.R&D activities relate to technical innovations, improvements of mining equipment, research and evaluation of conditions for extracting coal seam and/or overburden and mitigation of environmental impacts, utilisation of coal in new products. The company spends considerable amounts on reclaiming affected land and creating a new post-mining landscape.Our dialogue with influential stakeholders in the region where we operate contributes to the long-term improvement in the quality of life of local residents. Such dialogue with communities in the last ten years has been instrumental for confidence building. SD Company helps to develop many projects of towns and villages in its vicinity. The stable and transparent relations with our neighbours are in accordance with our basic principles of corporate social responsibility.

Dec 6, 2010

By Gabriela Lemos Lages

Os parâmetros influenciadores do processamento mineral para a concentração magnética, como granulometria das partículas, fluxo de alimentação da polpa, susceptibilidade magnética, atuam de forma conjunta em uma planta de beneficiamento. Foram analisadas amostras de polpa contendo sulfetos de níquel, cobre e metais preciosos em seis amostragens objetivando medir a eficiência de um separador magnético de tambor de 750 Gauss em um circuito primário de britagem. O rendimento do equipamento na planta industrial foi comparado com os parâmetros medidos em laboratório. Os resultados obtidos da granulometria médias das partículas da polpa para 80% e material passante (P80) foram: 150 µm, 300 µm, 163,6 µm, 146,1 µm, 287,5 µm e 164,8 µm, e a taxa de alimentação do circuito variou entre 30,2 tph e 55,2 tph, com pressão de lavagem média de 1,0 kg/cm3. As amostras foram submetidas ao balanceamento metalúrgico utilizando o software Bilmat 9.5, após os resultados dos ensaios de caracterização: ICP-metais básicos, Satmagan e LECO-S. O percentual médio de recuperação magnética do laboratório foi de 80,1%, enquanto na planta a média foi de 96,38%, com a eficiência da planta em torno de 20,8% superior à recuperação magnética em laboratório.

Oct 30, 2017

By Amitava Gangulee, Michael B. Bever

The order-disorder transition in Ag-Mg alloys in the range 17 to 26 at. pct Mg was investigated and some thermodynamic, electrical and mechanical properties of ordered Ag-Mg alloys were measured. A modification of the phase diagram is proposed on the basis of measured transition temperatures. The stability of the ordered structure is analyzed in terms of the quasichemical theory. Kinetic aspects of the order-disorder transition were also investigated. The energies of ordering at 273°K of Ag-Mg alloys were measured by liquid metal solution calorimetry. The electrical resistivities and the tensile Properties of the ordered alloys were measured. The exothermic energy of ordering increased with magnesium concentration up to the composition Ag3Mg; it is discussed in terms of the quasichemical theory. Pronounced order hardening was observed and can be explained by several strengthening mechanisms, which are particularly effective because of a change in crystal structure associated with the ordering transition. IN silver-rich solid solutions containing approximately 17 to 26 at. pct Mg, long- range ordering may occur during appropriate therma1 treatments. Clare-brough and Nicholas1 first detected such long-range order in the solid solution of composition Ag3Mg and suggested that the unit cell of the superlattice contained 256 atoms. x-ray2 and electron diffraction3 investigations confirmed the occurrence of long-range order, but indicated a shifted Ll2-type structure. On the basis of recent X-ray measurements the crystal structure of ordered Ag3Mg has been confirmed as type D023.4 The present paper is concerned with the order-disorder transition in silver-rich Ag-Mg solid solutions and some thermodynamic, electrical, and mechanical properties of the ordered alloys. The effects of short-range order on the properties of silver-rich solid solutions containing up to 26 at. pct Mg are discussed in a concurrent paper.5 1) EXPERIMENTAL PROCEDURES 1.1) Preparation of Specimens. Specimens of Ag-Mg alloys containing from 18 to 26 at. pct Mg were prepared in the form of 1.0-mm-diam wires as described in Section 1.1 of Ref. 5. Disordered specimens were prepared by annealing at 773°K for 1 hr and quenching into iced brine. Ordered specimens were prepared by annealing at 773°K for 1 hr and slowly cooling to room temperature over a period of 15 days. The specimens were stored at 78°K. 1.2) Resistivity Measurements. Electrical resistivi- ties were measured by a potentiometric method.' Equilibrium values were obtained at several temperatures. The kinetics of ordering were investigated by following the time-dependent changes of the resistivity of initially disordered specimens during annealing. The specimens were enclosed in copper capsules and immersed in salt pots; the heating up was accelerated by injecting preheated helium into the capsules. 1.3) Calorimetry. The energies of ordering of the alloys were measured in a tin solution calorimeter as the difference between the heat effects of additions of completely ordered and disordered specimens of the same composition. The procedure and the method of calculation have been described.6 Magnesium was used for thermal compensation in most calorimetric runs in order to improve the accuracy.677 1.4) Mechanical Tests. Tensile tests were carried out with wire specimens at room temperature as described in Section 1.5 of Ref. 5. Microhardness measurements were also made.? 2) RESULTS AND DISCUSSION The characteristics of the order-disorder transition of silver-rich Ag-Mg solid solutions will be discussed first. Some thermodynamic, electrical, and mechanical properties of the ordered alloys will then be considered and compared with the corresponding properties of dis-disordered alloys. 2.1) The Order-Disorder Transition. 2.1.1) Thermodynamic and Structural Aspects. The transition temperatures Tt were determined from discontinuities in the slope of the equilibrium resistivity vs temperature curves. Normalized curves for three compositions are shown in Fig. 1. The transition temperature increases with the magnesium concentration and reaches a maximum at the stoichiometric composition Ag3Mg. The transition temperature of the alloy Ag3Mg was measured as 665° ± 2°K and compares with published values of 660°,1 663°,8 and 66°k.3 In the slopes of the resistivity vs temperature curves of alloys containing 22.2 and 22.5 at. pct Mg, discontinuities were observed at two temperatures. Such upper and lower discontinuities indicate a two-phase field. A modified form of the published phase diagram9 is shown in Fig. 2. A two-phase field was found only on the low-magnesium side of the composition Ag3Mg. On the high-magnesium side, the existence of a two-phase field could not be established because of insufficient resolution, but such a field must be present. This part of the phase diagram can be made complete by a eutec-toid-type reaction a = (a' + ß). The existence of a boundary between the two-phase fields (a + ß) and (a' + ß) is also in accord with published lattice parameters.3 The crystal structure of ordered Ag3Mg (type Do23)

Jan 1, 1969

This paper identifies the challenges and opportunities for mining companies and communities in investing in human rights compatible, credible, effective and representative company-community relationships.   The paper draws on the work of Professor John Ruggie, Special Representative to the United Nations Secretary General on Business and Human Rights, and his Protect, Respect and Remedy framework for business and human rights, The CDA Collaborative Learning Project, and the experience of Oxfam Australia. This paper begins with the premise that Australian companies commence operations offshore with high expectations and a willingness to work harmoniously with local communities. However, as companies increasingly engage in global operations - particularly in weak governance and conflict zones - the challenge to establish and sustain rights compatible, meaningful, corporate community relationships and grievances mechanisms becomes both more complex and necessary. Establishing trust and honouring commitments made to communities, including legacy issues, is a critical component in good corporate community relations.   The second part of the paper will identify some of the impacts and challenges of mining that need to be addressed in corporate community negotiations and consultation. Respect for indigenous people's rights and their right to give or withhold consent for a project to proceed is increasingly evident, as is the growing global expectations with regard to revenue transparency. As such, key challenges include: grievance mechanisms; free prior and informed consent; transparency and accountability; the gender impact of mining; resettlement, compensation and benefit sharing; and security issues.   Finally, the paper will provide practical guidance to companies on how to establish effective corporate community relationships. It will include examples, such as human rights impact assessments, gender impact assessments, and establishing local level grievance procedures. The paper will include an Oxfam Australia case study of a dialogue mechanism at Tintaya copper mine in Peru.

Jun 1, 2010