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By John W. Chandler

The property of the lava Cap Gold: Mining Corporation is in the Nevada City-Grass Valley mining district about 5 miles east of Crass Valley, Calif. At present (July 1940) the plant is mining end milling about 390 tons of gold-silver ore a day; about 310 men are employed. This paper describes the mining methods used and presents mining costs for 1939, when 60,704 tons were mined by cut-and-fill stoping and 55,676 tons by square-setting.

Jan 1, 1941

By Robert C. Speck

The U.S. coal industry has long utilized the pillar-extraction mining technique as a method for maximizing coal recovery. Like longwall mining, it causes large-scale movements that progressively propagate from mine-level to the ground surface and may affect the groundwater regime, surface drainage and surface structures. The U.S. Department of Energy, in an effort to foster in- creased use of total extraction mining techniques, has recognized the need for a better understanding of these movements that will lead to a greater compatibility between coal mining and present and future land use. As part of that goal, GAI Consultants, Inc. is currently in- stalling instrumentation to monitor the ground movements associated with pillar extraction mining at Kitt Energy Corporation's No. 1 mine in northern West Virginia.

Jan 1, 1982

By A. Kontopoulos

The Olympias Mine in Northern Greece is producing an extremely refractory gold-bearing arsenical pyrite concentrate, containing on the average 41 3 S, 40 3 Fe, 10-12 3 As, 25 ppm Au and 35 ppm Ag. During the process selection stage, more than a dozen alternative technologies? were considered and an in-depth analysis was prepared for the three most promising, ie roasting, pressure oxidation and biological oxidation. Detailed capital and operating cost estimates were prepared, based, where appropriate, on laboratory and pilot-plant tests. A number of criteria was used for process evaluation and selection, including capital and operating costs; environmental impact, gold' recovery, stage of development, etc. Based on the above evaluation, the Sherritt Pressure Oxidation Process was finally selected. A detailed description of the process selection stage, supported with laboratory and pilot-plant test results on many of the processes considered, will be? presented.

Jan 1, 1989

By Y. G. Sun

This paper mainly reported separation manganese silver oxidized ores process by amylum de-gradation reduction and its influencing factors. When dosage is given according to nMn : nH2SO4 : n(C6H10O5)n : nH2O=1:k21.8: k116.66:30, the amount of up to 95.93% Mn leach rate and less than 2% silver loss can be obtained. Cyanidation process was used to extracted silver from leaching Mn residues. Silver leach rate could reach 94.15% at consumed amount of 1kg/t NaCN for 1h. Silver leach recovery rate was more than 92.27% by leaching Mn and cyanidation two-step processes so manganese and silver were separated effectively.

Jan 1, 2014

By R. L. Cosgriff

A commercial, battery-powered mine vehicle has been equipped for remote operation in coal mines. This vehicle is controlled by an operator from the remote station. Command signals originating at the remote station as well as video and data signals originating on board the vehicle are relayed between the remote station and vehicle using a single coaxial line. This coaxial line is normally 2,000 feet in length and is reeled in and out from a drum mounted aboard the vehicle The vehicle has a maximum speed of 6 ft/sec and a minimum speed of 4 ft/sec using 36-volt excitation of the traction motor. If this traction motor is excited by two of the three batteries, 24-volt excitation, the vehicle will travel at approximately 2 ft/sec. The speed can be reduced by the operator to 1 ft/sec. This vehicular system has been tested in coal mines. Presently, the major limitation of this system is associated with fatigue failure of the splices in the coaxial line and lack of mobility caused by its 3-wheel design.

Jan 1, 1974

By N. X. Feng, S. G. Zhou, X. L. Wu, J. P. Peng, Y. Z. Di

"Szaibelyite–suanite type ore is rich in magnesium oxide and boron oxide. We propose a new method to extract both metallic magnesium and valuable residues rich in boron by reduction using metallic aluminium.Thermodynamic analysis of the reactions between aluminum and MgO, Mg2B2O5, and Mg3B2O6 was carried out. The effects of CaF2 addition, temperature, mass of Al, and pellet formation pressure on the extraction of magnesium were also investigated experimentally.The results indicate that the magnesium oxide phase can be displaced from 2MgO-B2O3 and 3MgO·B2O3 by CaO in the reduction system. The reduction ratio of magnesium oxide was 38% without calcium fluoride addition, increasing to 94% with 5.1% calcium fluoride. The reduction ratio increased with increasing temperature and mass of Al. To obtain a higher reduction ratio, the reduction pellet should be formed under a reasonable pressure.IntroductionBoron and its compounds are widely used in textiles, borosilicate glass, metallurgy, fertilizers, and nuclear shielding. Boron resources are mainly found in Turkey, the USA, Russia, and China. In Liaoning, China, there are abundant szaibelyite–suanite type ores that are rich in magnesium oxide and boron oxide. Szaibelyite and suanite ores are used to produce borax by a carbon dioxide– soda process. Annually, 2 Mt of waste materials containing 3–20% B2O3 and 2–25% MgO are produced during the process. It is necessary to make use of these waste materials containing high concentrations of boron oxide and magnesium oxide to avoid environmental problems as well as for economic reasons (Ozdemir and K1pcak, 2007)"

Jan 1, 2016

By N. Barton

Large scale tests were conducted on quartzitic gravel and crushed sand-stone to investigate pertinent geotechnical properties for backfill support of egress shafts. Such shafts are envisaged for rapid launching of deep-based missiles. The backfill support is designed to resist shaft closure under dynamic loading, and must also drain rapidly to a lower catch chamber to allow launching. Large scale tilt shear tests were performed to measure the internal shear strength of the two backfill materials. Shaft filling and emptying tests were conducted in a 12 ft deep, 3 ft diameter model section of shaft drilled in sandstone. One half of the model was smooth bored, the other half rough-surfaced to represent drill and blast surfaces. Vertical and horizontal pressure cells indicated that stress only built-up during the first 1 to 1 ½ diameters of filling, due to the high-sidewall friction of 38° for the rough shaft and 31° for the smooth shaft. Interface sliding tests were performed to confirm these figures. Static and dynamic deformation tests were also per-formed, and indicated moduli as high as 56,000 psi, which will give excellent shaft support. Both the shaft support characteristics and the ease of emptying of gravel look particularly promising.

Jan 1, 1983

By C. J. Simensen, R. Østhus, H. J. Roven, K. G. Skorpen, H. Kalager

"This work encompasses co-extrusion of alloy Al4.5Mg at the core and rapidly solidified Al4.5Mg1Ag forming the surface layer. The goal is to produce a multi-material by co-extrusion having a relatively hard surface as compared to a softer core. At the same time, work hardening in both alloys is expected to be significant due to Mg in solid solution. Precipitation hardening at 160°C is studied by applying solution heat treatments at 560°C. The hardness increased from 80 to 130 VH in the surface material after 236 h. Surprisingly, the Al4.5Mg alloy also shows pronounced aging at this temperature, i.e. from 70 to 90 VH. The relatively high solution heat treatment temperature introduces grain growth in the core, but this is insignificant for the RS surface alloy. Blisters forms at the surface and cracks follows large portions of the interface. However, the tensile ductility is significant in all conditions due to very pronounced work hardening, i.e. for the as co-extruded, T6, under- and over-aged. The elongation at fracture ranges between 40–45% and the tensile strengths 240–275 MPa. The tensile properties increase linearly with the thickness of the RS alloy, i.e. following the rule of mixtures.INTRODUCTION Al-Mg alloys in 5xxx-series are classified as non-heat treatable wrought alloys (Polmear, StJohn, Nie, & Ma, 2017). The formation of the binary ß-Al8Mg5 does not give a substantial increase in the strength of the alloys (Mondolfo, 1976). When a third element like Ag, Cu or Zn are added, G.P.?zones are formed at low temperatures and intermediate, partial coherent phases are nucleated somewhat higher temperatures and finally a ternary, equilibrium phase is formed (Auld, 1968; Cousland & Tate, 1986; Mondolfo, 1976). Both the formation of G.P.?zones and intermediate phases increase the hardness and strength of the materials. An intermediate, hexagonal T´?phase is formed in Al-5 wt%Mg-1wt%Ag, and finally the equilibrium, cubic phase (Al,Ag)9Mg5 is nucleated (Cousland & Tate, 1986; Mondolfo, 1976)."

Jan 1, 2018

In 1976 the Pitjantjatjara Council was established under the Associations Incorporation Act 1985 (SA), for the initial purpose of organising and bringing together three similar Indigenous groups. These members of the Pitjantjatjara Council of Central Australia were demanding land rights and to legally protect their traditional lands. The Land Rights movement was more focused on the South Australian Government that became more receptive to the general notion that Aboriginal freehold land could be attainable.For almost five years, Pitjantjatjara CouncilÆs intense negotiations took place with the Dunstan and Tonkin Governments culminating in the final passage of legislation by 1981. A bi-partisan approach by Government and opposition applauded by all South Australians for its mature and socially responsible actions, in line with the Aboriginal Land Rights (Northern Territory) Act 1976 (Cth). Despite the similarities between South Australian and the Northern Territory Land Rights legislation, there still remains one obvious distinction. In the Northern Territory case, its legislation established æLand CouncilsÆ as statutory authorities that are responsible for the management and use of designated Aboriginal lands. On the other hand, South Australian legislation fails to include any reference to æLand CouncilsÆ as defined in the Northern Territory Act. The intention of establishing such æLand CouncilsÆ in the Northern Territory was, and is to provide legal, anthropological and other expect advisers that respond to the wishes and opinions of Traditional Aboriginal Owners. Negotiations between mining companies and Land Councils, will, after the granting of mining leases, monies are then transferred to those Councils being a percentage of royalty entitlements. While the Pitjantjatjara Land Rights Act 1981 (SA) (Act) does provide royalty arrangements to Anangu Pitjantjatjara (AP), a body corporate pursuant to the Act as a Landholding Body (and not as a æLand CouncilÆ), it does not provide any royalty payments for the legal and anthropological services by the Pitjantjatjara Council for providing essentially similar services as the Northern Territory Land Councils. The limited services by AP do provide complimentary services from other organisations û including the Pitjantjatjara Council. There are approximately 4000 Anangu members who reside on AP Lands and more than 1000 other Anangu members live near AP Lands in Western Australia and the Northern Territory. These people are defined as APÆs æTraditional OwnersÆ by virtue of their affiliation to portions of AP Lands. As a result, the depth and understanding of spiritual beliefs and customs are strongly present as it relates to the whole of the Lands. Most of these members reside at permanent communities that spread unevenly about the northern and south-western parts of AP Lands. In addition, there are numerous æHomelandsÆ where families and extended families have establish homes, with electricity and water supplies on those Traditional Lands (see Appendix 1 and 2 of this paper depicting the map showing AP Lands and also showing stunning photographs taken during late last year). All roads and airstrips are unsealed between communities and Homelands and the essential services to all communities are limited and costly to provide, and require continuous upgrading. Capital expenditure on infrastructure is sorely needed and alarming levels of unemployment is of serious concern. Tjilpi (older) Anangu members have continually discuss the urgency to provide employment and education for the future of their children and grandchildren while balancing the needs of maintaining cultural and spiritual considerations. It is thus a growing realisation by many Traditional Owners that long-term benefits occur as a result of exploration and production of oil or minerals. There are promising results from Primary Industry and Resources of South AustraliaÆs (PIRSA) Aero-magnetic Surveys on the Musgrave and Mann Ranges and soon to be completed surveys of the remaining southern half of AP Lands (see Appendix 3). PIRSA and mining companies û such as Rio Tinto Exploration Pty Ltd and Delta Gold NL û have been more conscious of the necessity for improving the dissemination of information to Traditional Owners and to AP members. With recent findings of large nickel deposits just over the border in Western Australia, there is a strong indication that discoveries may occur on AP Lands as similar geological information is present on the east Musgrave Block. Consequently there are concerted efforts by the legal and anthropological services of the Pitjantjatjara Council to arrange Workshops and Summit meeting to give extra information û particularly information concerning the true effect of large-scale mining operations û to members to properly consider these proposals. Pitjantjatjara Council will play a major role in any decisions effecting Traditional Owners and AP, and will ensure orderly and professional services when dealing with legal, cultural and sensitive matters. This paper addresses the historical and current relationship between Pitjantjatjara Council and AP, with an emphasis on mining operations on AP Lands. It argues that future economic and social development on AP Lands hinge predominantly on the legal recognition of the Pitjantjatjara Council for its ongoing role, responsibilities and protection afforded to AP and its Traditional Owners.

Jan 1, 2002

By Richard I. Barnhisel

At the Sinclair Study Site it was found that the deeper the soil the greater the yield of corn, soybeans, wheat, alfalfa, and timothy. Yields at this location were generally lower than those at the Alston Surface Mine. At Alston the non-prime land treatments generally produced greater yields for all crops than did the prime farmland treatments, however, the intermediate soil thickness, 20 cm topsoil over 40 cm of subsoil, gave the best yields, provided it's subsoil had been limed. From a chemical point of view, acidic spoils do not need to be buried by 120 cm or 4 feet of soil, provided adequate lime is applied to these spoils as a barrier prior to placement of good quality topsoil and only forage crops are to be grown. The burial depth must be increased to as much as 75 cm when grain crops such as corn or soybeans are to be grown. This response to burial depth appears to be related to water storage needed by the crop and not due to toxic effects of the spoils. A conventional farm tractor-mounted subsoiler increased yields of soybeans and corn the first one or two years, but the effect was diminished with time. Subsoiling did not produce significant increases for alfalfa or wheat. However, ripping with a bulldozer produced significant yield responses, especially for corn and soybeans, that have lasted for at least three years. The ripping effectively reduced the bulk density at least within the zones through which the ripper had passed. Liming the upper 20 cm of subsoil significantly increased yields of alfalfa, corn, and soybeans. There also appeared to be an interaction between this lime treatment and soil depth. Yields of some grain and forage crops may be high enough to meet target levels for bond release for prime farmland. Based on the present study, one should not expect corn yields to be high enough to meet bond release. This statement should not be considered final since the experiment is not complete.

Jan 1, 1983

By Wynand Erasmus, Terry A. Jones

The Kelsey Centrifugal Jig (KCJ) utilizes the application of centrifugal force (and the resultant enhanced gravitational field) to conventional jigging technology principles to successfully process materials where the valuable constituent particulates are very fine and/or where there is a small specific gravity differential between these and the gangue minerals. The KCJ has been successfully employed in mineral sands applications in Australia for approximately 12 years. More recently, the KCJ has been tested and installed on zircon tailings dump retreatment projects in Australia and the USA, while being considered for similar projects in RSA, and is about to be installed in zircon tailings processing duties in India and Africa and in a tin removal duty in a rutile circuit in Australia. Extensive test work has been carried out on these applications and some typical performance data is presented in this paper. Information is also provided on the principles of operation of the KCJ and on the keys to a successful KCJ installation.

By Ulises Crossa Archiopoli

We describe a technique that allows rapid imaging of the thermal diffusivity of the sample by a modified photo-thermal technique. The thermal diffusivity in hardened steels strongly correlates to the hardness. Hence in a noncontact manner and with optical microscope resolution, a 2D map exhibiting the crystallographic phases and hardness of the sample can be retrieved. Two almost collinear laser beams scan the surface, one as a modulated pump and a second as a CW probe. The deflection of the probe carries information on the thermal expansion of the sample and with it, on the thermal diffusivity. It is shown that a single determination of the time delay of the modulation of the probe beam can be used to retrieve the thermal diffusivity.

Jan 1, 2010

By Anthony H. Tawil

Modern, high-speed machines used in the manufacture of paper require foundations with stringent settlement constraints. To fulfill this requirement, caisson piles, extending into bedrock, were selected to support a paper machine in Baie Comeau for the Quebec North Shore Paper Company (QNSPCo.). This was the fourth machine in an existing paper mill, and its construction was part of an expansion program which included the building of associated structures such as a wood room and chip storage building, and other facilities, Figure 1. The paper mill in Baie Comeau, Quebec, is located in an area which has extensive deposits of sensitive marine clay which are transformed into a viscous liquid when disturbed by external forces such as the driving of piles. Loss of ground and soil disturbance as affected by piling activity assumed considerable importance in the design and construction of the caissons particularly in view of the proximity of existing plant facilities, including another paper machine.

Jan 1, 1987

By J. W. Paul

The United States Bureau of Mines has made a study of roof control in 68 mines operating in the Pittsburgh coal bed in Pennsylvania, West Virginia, and Ohio. In making these studies, much information was also obtained on various exact methods of development and pillar extraction as practiced by this large group of mines. It is proposed in this paper to describe these methods, by which this group of mines in 1931, a year of reduced industrial activity, produced 28,123,000 tons of bituminous coal - 7.4 percent of the national production for the same year and an amount equal to the combined production of the coal mired in the States of Alabama, Colorado, New Mexico, Utah, and Wyoming. The results of these studies, insofar as they pertain to the prevention of injuries from falls of roof, have been published by the Bureau of Mines. In this paper only a few mines typical of each system will be described; however, should the reader be interested in other details with respect to these mines, he may refer to the following publications: T.P. 522, 1932, 43 pp. Falls of roof and coal in mines operating in the Pittsburgh coal bed in Marion and Monongalia Counties, W. Va., by J. W. Paul and J. N. Geyer.- A study of nine mines in these two counties of northern West Virginia.

Jan 1, 1935

By Shuang Shuang Huang, John Fillos

Ozonation was evaluated as an alternative treatment process for leachates of municipal landfills. The study was carried out on leachate from the Fresh Kills Landfill, New York City. The leachate has strong tea color and BOD5 ranging between 90 mg/L and 130 mg/L. The average COD, TOC and NH3-N concentrations were 1800 mg/L , 550 mg/L, and 665 mg/L, respectively. The kinetics of the process were studied in a sparged batch reactor by developing concentration- time profiles for residual color and TOC. Continuous flow experiments were then carried out at two selected contact times. The process was found to be effective in the treatment of leachates for color and TOC removal.

Jan 1, 1992

By Isadora Almeida Rosa

Aços baixo-carbono com microestruturas ferrítico-bainíticos, bifásico, ou multifásicos têm características apreciáveis para a indústria automobilística, pois, combinam resistência, ductilidade e conformabilidade, permitindo produzir chapas mais finas resultando na redução do peso. Com o intuito de avaliar as características mecânicas e microestruturais obtidas através da variação da temperatura de bobinamento, desenvolveu-se um estudo a partir de um aço baixo carbono com microadição de molibdênio e nióbio, onde se verificou a possibilidade de produzir um aço dual phase na forma de chapas laminadas a quente, em escala industrial. Pode-se verificar que para menores temperaturas de bobinamento, obteve-se melhor desempenho quanto ao aumento da resistência mecânica e garantia de uma alta ductilidade vinculados a um refino expressivo no tamanho de grão da matriz ferrítica em conjunto com uma segunda fase com evidência de ilhas de martensita.

Aug 16, 2017

By Christophe Bragard

The Los Angeles Metro Eastside Extension light rail project included a 1.5 mile underground segment, which consisted of twin 18'?10" ID tunnels, bored with two EPB-TBMs. One of the major project challenges after the completion of the bored tunnels was the excavation of six cross passages within alluvial geology below the water table and with low ground cover. Sequential excavation methods were employed and this paper details the design, ground treatment, support measures, and construction methods used to mine these cross passages beneath the congested urban streets of the City of Los Angeles.

Jan 1, 2008

By Cyril Wells, Paul E. Busby, Donald P. Hart

EARLY workers in the field have established that the diffusion of nitrogen follows normal diffusion laws. Concentration-penetration data from layer analyses of reasonably pure iron specimens nitrided in an atmosphere of CO-NH, are given in the literature,' and were utilized to calculate diffusion constants for nitrogen. The diffusion of nitrogen in y-iron may be represented approximately by the equation D - 1.07x10-' e-:".'m'"'r The diflusion coefficients, D, given by this relation represent mean values, since carburization occurred simultaneously with nitriding. The rate of diffusion in a-iron has been determined from calculations based on data obtained by measuring the internal friction of samples at each of several frequencies and temperatures.' The expression for the diffusion of nitrogen in a-iron derived from these experiments is D= 1.4x10-1 e-it tudent Increasing carbon content decreases the diffusion of nitrogen in a-iron.3 Oxygen, either dissolved or combined, has been shown' to exert a marked influence on the diffusion of nitrogen from a nitriding atmosphere. D values increase rapidly with increasing amount of dissolved oxide in the metal, but diffusion is completely inhibited if preliminary oxidation has produced the slightest trace of iron oxide on the surface. Diffusion coefficients have also been calculated from permeability and solubility data,' but these values are of questionable accuracy since the boundary conditions assumed may not actually exist. Experimental Method The method selected for determining the diffusion coefficient of nitrogen in a-iron in the present investigation was the so-called fractional saturation method. This method consists of heating the specimen in an atmosphere of H2-NH8 mixtures of known composition for a predetermined time. Following this treatment, the specimen is analyzed for nitrogen; and the diffusion coefficient is calculated from a known relationship of the fractional saturation, time of diffusion, and dimensions of the specimen. This relation is based on a solution of Fick's second law and assumes that the surface of the specimen immediately reaches a given concentration which remains constant during the diffusion anneal. Tabular solutions are available4-5 and provide the relationship between fractional saturation and the quantity \/Dt /a, where D is the diffusion coefficient in cm2 per sec, t is the time of the diffusion anneal in seconds, and a, in the present experiments, is the half-thickness of the slab specimen in cm. The method is adequately discussed elsewhere.9-10 Material The material for this study consisted of 3/32 in. thick (0.24 cm) carbonyl iron plate. The major impurities in this iron are oxygen and carbon, which are readily removed by long time high temperature treatment in an atmosphere of purified hydrogen. In order to reduce the diffusion anneal time for saturation runs, some of this material was rolled to a thickness of 0.015 in. (0.038 cm) prior to the hydrogen treatment. Hydrogen treatments were carried out in a hydrogen-purified Armco iron tube heated in a global

Jan 1, 1957

By J. L. Holman

The Bureau of Mines, at its Rolla Metallurgy Research Center, has devised methods for separating and reusing the major portion of waste plastics discarded in urban and industrial refuse. Waste plastic concentrates from a local collection drive, recycling center collections, urban refuse pilot plants, and the secondary metals industry were separated into three major thermoplastic families--polyolefins, styrenes, and vinyls--based on differences in density using a Bureau-designed sink-float-elutriation hydraulic separator. Other separation methods and systems such as air classification, jigging, liquid media, screening, and electrostatics were studied. Vinyl plastics contain up to 50 percent HC1. It was found that over 90 percent of the HC1 in vinyls can be recovered as usable hydrochloric acid by pyrolysis at 350° C. The remaining pyrolysis products which had heats of combustion in excess of 12,000 Btu/lb, could become valuable as a future source of energy. A characterization study conducted on eight chopped wire insulation wastes from secondary copper and aluminum processors showed that most wastes contained 2 to 7 percent residual metal and large percentages of vinyl. The residual metal content of some of these wastes was lowered to 0.1 percent and the vinyl portion segregated using various separation techniques. The research also suggests ways in which reclaimed thermoplastics may be fabricated into useful products.

Jan 1, 1974

By Lucas Xavier Soares de Souza

No contexto de eficiência energética nos setores automobilístico e aeronáutico, a redução de peso em estruturas assume um papel importante. Como alternativa para isso, as espumas metálicas, mais especificamente, as espumas de magnésio e de ligas de magnésio, surgem com grande potencial. Isso se deve, primeiramente, às propriedades desse elemento químico, que é o mais leve entre os metais estruturais. Já a estrutura em forma de espuma aparece como fator capaz de potencializar as propriedades desse elemento. Um dos processos para produção de espumas de magnésio é a metalurgia do pó e uma das etapas desse processo é a compactação dos pós. Busca-se com este trabalho, avaliar a densidade relativa de amostras que foram compactadas a partir da prensagem uniaxial a frio de pós da liga de magnésio AZ91 com hidreto de titânio. Foi verificado que para uma mesma pressão, variando a granulometria da liga AZ91 e a quantidade de hidreto, a variação nas densidades relativas é desprezível. A partir das curvas obtidas nos ensaios de compactação foi possível verificar que na faixa de 130 a 230 MPa ocorreu deformação plástica dos pós de forma gradual e foi possível constatar que a partir de 300MPa não ocorre variação significativa da densidade relativa com o aumento da pressão.

Oct 30, 2017