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By Qi Jingyue, Wang Zhongquian, Yang Nianhua

Qinling Tunnel is the longest tunnel in China. The rock stratum is very hard rock - intact mixed gneiss. At the beginning of the construction, drift-pilot excavation is very costly due to the use of regular drill and blasting methods. After tests on the acoustic impedance match between rock and explosive, watergel explosive, which has a high velocity of detonation and high brisance, has been used for hard rock blasting. In addition, different cut plans have been compared. It was found that four-large-hole cut is the most effective. And the number of drillholes and specific charge cut down and the average advance reaches more than 94% of the blastholes depth. Thus, the difficult problem of hard rock blasting in drift pilot is successfully solved, while safe and quick construction is guaranteed.

Jan 1, 1998

By Willy Ank de Morais, Márcio de Morais Tavares, Luan Matheus Peres, Érika Elis Kuo, Marcelo Costa Choukri

Eventualmente torna-se necessário fazer adaptações em estruturas de concreto durante ou após sua execução, de modo a adequar componentes em concreto armado. Essas mudanças não previstas no dimensionamento das estruturas pode comprometer a resistência aos esforços de tais estruturas, invariavelmente necessitando da introdução de um reforço estrutural. As técnicas mais conhecidas e utilizadas para reforços em estruturas de concreto armado são: adição de barras de aço, chapas de aço, fibra de carbono e protensão externa. Adicionalmente, ensaios práticos tornam possível quantificar a eficiência do reforço de um estrutural adotado, inclusive para verificar a eficiência entre a aderência, sob o ponto de vista estrutural, dos materiais empregados. O método de reforço de estruturas de concreto armado por meio de vergalhões adicionais é a técnica mais utilizada atualmente por ser de fácil execução, não precisar de mão de obra especializada e possuir o melhor custo x benefício. Assim sendo, este trabalho avaliou, a eficiência do reforço estrutural em uma viga submetida a furo não previsto em projeto utilizando os métodos de adição de vergalhões e barras de aço na região tracionada da viga. Os resultados obtidos foram comparados com os observáveis em uma barra de concreto, com área de aço normal.

Mar 1, 2019

By W. P. Haynes

The Bureau of Mines has been studying a modified steam-iron process using coal-derived producer gas for making either hydrogen plus carbon monoxide or methane. To provide a guide for this experimental study, compositions of equilibrium product gases for the reaction of steam plus carbon dioxide with iron were calculated and are discussed in this report. The calculations, which are described in this report, are based on thermodynamic data in the literature and cover temperatures from 800° to 1,300° K., pressures from 1 to 30 atmospheres, and hydrogen-to-carbon atomic ratios in the gas of 4 to 12. The equilibrium gas compositions are discussed in regard to making hydro-gen, carbon monoxide, and methane in the oxidation step of the modified steam-iron process. From the viewpoint of thermodynamics alone, assuming the reactions reach equilibrium, the discussion considers the effects of temperature, pressure, and composition of feed gas upon the composition of the product gas, the degree of oxidation of the iron, and the possible deposition of carbon. The results indicated the following: (1) Nearly all the carbon can be converted to methane at low temperatures (800° to 900° K.) and high pressures (over 20 atmospheres); (2) to obtain high yields of synthesis gas, high temperatures are required. For example, at 30 atmospheres, a temperature over 1,200° K. is required to convert 60 percent of the steam plus carbon dioxide to hydrogen plus carbon monoxide. Lower temperatures may be used at lower pressures) (3) oxidation of the iron increases with increasing pressure and decreases with increasing temperature; and (4) process conditions favoring carbon deposition were found within the range of variables studied, but it is thermodynamically possible to operate the oxidation process with steam and carbon dioxide outside this range of carbon deposition.

Jan 1, 1961

By Robert W. Hunt

The memorable features of American history have been making fast during the last century, and notably so since 1860; and they are by no means confined to political or to any one branch of scientific development. Of all the industrial arts, none show a greater change or 'a mightier progress than the Bessemer manufacture. And this year, while we are celebrating the first centennial of our national life, we can also celebrate the first decennial of American Bessemer practice. While not forgetting or undervaluing what has been done in other countries, I have thought that a brief history of the introduction and development of the Pneumatic or Bessemer process in America would be of interest. In 1863 the Kelly Pneumatic Process Company was formed and an arrangement entered into with William Kelly, who had taken out letters-patent of the United States, Nos. 16,444; 17,628, reissued as 505; 18,910, dated January loth, 1857; June 23d, 1857; November 36, 1857; and December 22d, 1867, respectively. This association mas composed of the Cambria Iron Company, E. B. Ward, Park Brothers & Co., Lyon, Shorb & Co., Z. S. Durfee, and, later, Chouteau, Harrison & Valle joined the combination. Not satisfied with possessing the control of the Kelly patent, they sent Mr. 2. S. Durfee to England, to secure for this country Mushet's patent on recarburization, No. 17,389, dated May 26th, 1857, the same having been taken out in England on September 22d, 1856. In this Mr. Durfee was successful. Previous to the application of William Kelly for a patent, Henry Bessemer, of England, had taken out patents dated February 12th, 1856, and August 25th, 1856, in this country. Kelly claimed priority in the discovery of the principles of the process, and the Patent-office allowed his claim by granting him his patents. In the autumn of 1862 Mr. Alexander L. Holley, while in England, was impressed with the importance of Mr. Bessemer's invention, and so fully foresaw its future, that, upon his return to the United States, he induced Messrs. John A. Griswold and John F. Winslow, of Troy, New York, to join him in endeavoring to possess Bessemer's American patents. Mr. Holley returned to England in

By Metehan Erdogan, Orhan Gökçe Göksu, Ishak Karakaya

"An experiment (mixture) design was created to optimize the process parameters of the electrochemical reduction of CaW04 to W in molten CaCl2-NaCl eutectic mixture. Temperature, applied voltage and the length of Kanthal wire winding of the CaW04 pellets were selected as the process parameters that were allowed to vary between the predetermined minimum and maximum values. The rates of the electrochemical reductions were interpreted from the variations of current and total charge vs. time graphs under different conditions. The analysis pointed out that 640°C and 2.81 V resulted in the fastest reduction. Itwas seen that the effect of Kanthal wire winding on the output current was less pronounced when compared to the other two parameters.IntroductionFFC Cambridge Process [1] has been applied to a number of metal oxides in laboratory experiments to produce metals. In nearly all of these studies, the electrolysis temperature was around 900°C, the electrolyte was pure CaCl2 or CaCl2 containing salt solutions and the anode was graphite. However, it was recently shown that the electrochemical reduction process of metal oxides in CaCl2 containing electrolytes at the mentioned high temperatures was not suitable for tungsten production [2], It was reported that as soon as WO3 contacts CaCl2, the following reaction occurs:"

Jan 1, 2012

By M. Albertson

AT Cobalt, Ontario, Canada, a lake was drained to facilitate mining, by the Mining Corpn. of Canada, during the spring and early summer of 1915. Previous to pumping out the water, great quantities of sands and slimes from concentrating plants had been discharged into the lake and during and after the lake's drainage, its basin' Was a receptacle for tailing products. As the writer was at work along the shore line as the lake was being drained, he had a good opportunity to observe the changes that took place as the water was withdrawn. Some adjustments between the incoming sands and the mud in the lake had taken place before pumping was commenced. One of the most interesting results was the appearance of a small dome in a path the writer traversed twice a day for several months; he remembers distinctly the difficulty of crossing this. Cobalt Lake owed its existence to the gouging out of a rock basin by glaciation. The long axis of the basin closely follows the strike of a thrust fault of about 500 ft. (160 in.) vertical displacement. The lake was originally shaped somewhat as shown. The length was about 3000 ft. (914.4 in.), the width at the lower lobe was about. 1000 ft., and the, width at the narrows probably. 400 to 500 ft. The original depth of water varied from 20, to 30 ft. (6.1 to 9.1 m.), near where the island later was formed, to 60 to 70 ft. (23.6 to 27.6 m.) in the widest part of the lower lobe. At the narrows, the depth was 30 to 40 ft.. Above the bed rock was sand, with boulders near the bottom, and mud. During the building of the railroad in 1903, considerable filling was done along the right of way. With the commencement of mining operations, about 1905, waste rock and mill tailings were dumped into the lake. One of the mining companies operated a hydraulic giant to remove the glacial debris from several hundred acres of rock surface; much of the sand and clay from this operation was deposited in the. lake. About

Jan 2, 1921

By A. S. Malicsi, I. Iwasaki

Differential flotation of bulk sulfide concentrates from Duluth gabbro into copper and nickel concentrates could be implemented by first destroying the hydrophobic coating with ozone and then by recovering the copper concentrate with a copper-selective collector. A number of parameters involved in the use of ozone, such as the sequence and the conditioning time of ozone treatment, the pulp pH, and the level of xanthate addition, were investigated.

Jan 1, 1986

By Saulo Brinco Diniz

O presente trabalho buscou explorar a aplicação da nanoindentação instrumentada na caracterização microestrutural e mecânica de materiais metálicos. Para isso foi utilizado um ultramicrodurômetro (Shimadzu, modelo DUH–211S) e um microscópio (Olympus, modelo BX51M) a fim de analisar uma chapa laminada a quente de uma liga de alumínio 7475-T7351. De acordo com algumas das possibilidades apresentadas, pode-se concluir que a nanoindentação instrumentada é uma ferramenta poderosa para a caracterização de materiais metálicos.

Aug 16, 2017

[Scott Aberle Western Energy Co POB 99 Colstrip, MT 59323-0099 Randy Acre Joy Mining Machinery 2569 Silver Oak Ct. Grand Junction, CO 81505 Brian L. Acton Oxbow Carbon & Minerals Inc 1601 Forum P1-#P2 West Palm Beach, FL 33401 Laine W. Adair Genwal Resources Inc POB 1420 Huntington, UT 84528-1420 Kent Adamson Solvay Minerals POB 1167 Green River, WY 82935]

Jan 1, 1999

By Evan C. Morgan G

El presente texto describe el panorama historiográfico de la mina de Condoroma, trabajos y el uso de los métodos de exploración realizados en dicha zona. Situada en el distrito de Condoroma, provincia de Espinar, Cusco, las minas de Condoroma fueron anteriormente trabajadas por los españoles, pero es a partir de 1927 y con la compañía Gibson que los trabajos mineros se reactualizan y se emplea la construcción de un tunel corta-veta de 170 metros de longitud, que al encontrarse con la veta, la extendió a 30 m. Posteriormente en 1952, se interesa la firma Mauricio Hochschild, suscribiendo un contrato de Opción por tres años con el Sr. Carlos Herrera Rozas. Firmada la Opción, se procedió primero a explorar las minas de Kata, por contener vetas vírgenes, y luego, las de Condoroma. Entre los métodos de exploración utilizados estaban los piques, las trincheras, la limpieza superficial con tractor, la perforación con diamantinas y la exploración geofísica. Finalmente, y tras haber desarrollado este programa de exploración con diamantinas, se pudo fijar los valores comerciales del yacimiento minero, aunque a un costo un tanto elevado. Empero la utilización de este moderno método de exploración, permitió revalorizar los yacimientos abandonados y colocarlos dentro de un espacio productivo.

Jul 20, 1956

By K. Andres

This paper presents the vibrating mill technology and summarizes the grinding principle of ultra fine grinding. In addition, a variety of operations is described and the benefits of these different operating modes? product size and efficiency are specified. A case study of an industrial application is presented to show the integration of vibrating mills into grinding circuits. The primary focus is the overall process scheme of this technology, the installation and operating costs, as well as the design parameters required for best performance. The vibrating mill can be used in a wide range of applications for process engineering duties. For a wide range of applications, from soft to extremely hard products, which require ultra fine grinding, surface activation or homogenization, the vibrating mill is well proven. Due to its easy operation, versatility and operation efficiency, the PALLA? vibrating mill gains in importance in the mineral processing industry. Keywords: Coal, comminution, grinding, mineral processing

Jan 1, 2010

By L Terrusi

The Bungaroo Valley hosts a concealed Tertiary channel iron deposit (CID) along a 17 km stretch of its length. Bungaroo Valley is approximately 0.5 km wide upstream at its easternmost extent, and 3.5 km wide downstream where it joins the Jimmawarrada Creek. The valley follows the axial trace of an anticline that plunges gently to the southeast, and the CID infills the valley. Mineralisation extends to a depth of 230 m below the surface, and almost the entire deposit occurs below the water table. Bungaroo Valley cuts through the Buckland Hills and is bounded to the north and south by steep scarps capped with the resistant Dales Gorge Member of the Brockman Iron Formation. Basement rocks are believed to be mostly Wittenoom Formation shales and dolomites, with Mount McRae Shale and Mount Sylvia Formation also present. Deep, localised depressions appear at the base of the CID sequence towards the north edge of the upstream section of the valley, while downstream the basal CID contact is relatively flat and shallow. In both cases the profile of the CID surface closely mirrors that of the basal contact. The localised depressions seen in the upstream basal CID contact produce significant variations in CID thickness of up to 100 m over short strike distances. This uneven palaeotopography is most likely due to eddying and waterfalls forming within the riverbed prior to CID deposition during a time when the water table was much lower than at present. It may also be associated with possible karsting in an underlying dolomite unit and subsequent syn- or post-depositional collapse of the overlying CID. The irregular basal contact of the Bungaroo CID sequence has implications for mining in terms of pit design and resource accessibility.

Jan 1, 2007

This paper attempts to put into perspective the implications of the legal disclosure requirements for promoters and consultants when making statements concerning ore resources and reserves. The need to take account of non-technical as well as technical factors is highlighted.

Jan 1, 1987

By Robert C. Ellman

The Bureau of Mines studied lignite pulverization in a laboratory ring-roller mill. Both moisture content and the source of lignite were found to be important factors in pulverizer operation. Reduction of moisture content increased capacity and reduced power consumption, but predrying is more effective than in-the-mill drying in improving pulverizer operation. A combination predrier-crusher system produced significant improvements but other efforts to improve in-the-mill drying in the test mill were unsuccessful. Pulverization of frozen lignite was found to seriously reduce pulverizer capacity and increase power requirements.

Jan 1, 1972

By W Dodson

Major ions, d18O and d2H and Carbon-13 concentrations in groundwater from 30 bores near an open pit iron ore mine were used to better understand the chemical evolution of groundwater in the aquifer. The relatively depleted d18O and d2H isotopes of groundwater from various depths suggest that groundwater is recharged from intense rainfall events, with little evaporative effect. The 300 to 500 mg/L increase of major ions relative to that of rainfall is due to evapotranspiration of rainfall during recharge. Geochemical mass balance modelling suggests that the evapotranspiration of rainfall during infiltration through the unsaturated zone varies over six fold from 20 to 130. This coupled with the dissolution of CO2 from the unsaturated zone and partial dissolution of carbonates and gypsum from Tertiary sediments and carbonates from the Wittenoom Formation accounts for the current major ion, d18O and d2H distribution in groundwater. Despite the relatively dissected morphology and steep hydraulic gradient the results of this study highlight the dominance of vertical flow relative to horizontal flow. The study also shows the dominance of rapid recharge by significant rainfall events as an important component of the water budget for east Pilbara aquifers.

Jan 1, 2009

By Bruno Mendes Grillo

O presente trabalho tem por objetivo comparar dois aços produzidos em uma aciaria LD em processo de trefilação de arames, sendo um aço ultra-baixo carbono e outro de baixo teor de carbono (SAE 1005). Através deste desenvolvimento, barras com 12,7 mm de diâmetro foram submetidas ao processo de trefilação para se obter a bitola de 1,25 mm em dezesseis passes, onde foram determinadas as propriedades mecânicas por meio de ensaios de tração uniaxial, medidas de redução de área e dureza após cada passe de trefilação. Os aços estudados neste trabalho suportaram deformações verdadeiras da ordem de 4,6 em redução de área na trefilação e foi mostrado que o aço ultra-baixo carbono possui maior capacidade de deformação plástica que o aço baixo carbono. Com este trabalho foi possível determinar uma curva de previsão de resistência dos aços estudados em função de um plano de trefilação estabelecido, sendo esta utilizada para definição da aplicação final do produto.

Aug 8, 2018

Laboratory scale simulation experiments show that the adsorption capacity of Au(CN)Z- on activated carbon in the presence of organic plant contaminants is dependent on the particle size of the carbon. This observation suggests that fine carbon in a CIP contactor can protect coarse CIP carbon from fouling in a dirty CIP plant. A preliminary test of this concept was made using fine lignite coal as the organic scavenger in the presence of the CIP carbon Calgon GRC22 in an alkaline cyanide solution containing Teric 401, sodium ethyl xanthate and kerosene.

Jan 1, 1991

By Richard O. Kneisley

Microseismic activity observed in both the laboratory and underground indicates that a quiet period, associated with the closure of existing fractures and strongly influenced by coal seam microstructure, occurs prior to coal bumps. Field studies conclude that coal mine bumps occur against a background of this so-called microseismic calm. This Bureau of Mines report summarizes microseismic activity associated with face bumps and floor bursts in a deep, western U.S. coal mine. Results conclude that while bumps are often accompanied by panel-wide increases in microseismic activity, bumps are not only preceded by a localized decrease in activity, but occur within these quiet zones. The results of this study concluded that microseismic activity may be applicable to the global detection of potential bump-prone zones, but that future studies are necessary to confirm these findings and to improve the techniques for evaluating stress control effectiveness.

Jan 1, 1989

By K. A. Natarajan, I. Iwasaki

The meaning and the utility of redox potential (Eh) measurements in sulfide flotation systems are examined. Since some preliminary plant Eh and laboratory flotation data were available, experiments were made to establish the pH range at which a platinum electrode might be used for such measurements without much difficulty in aerated systems. Triangular wave voltammetry was used to study the surface conditions of the electrode immersed in pyrrhotite suspensions at different pH. The measured Eh both at the plant and the laboratory is interpreted in terms of the experimental water-oxygen line.

Jan 1, 1974

By F. G. Miller, J. M. Podgursky

Laboratory and pilot plant work on tabling of 14-mesh X 0 hydrocyclone under flow are summarized. Included are: operating principles of hydrocyclones and tables; performance of these two devices, separately as well as in combination; comparison of the combination hydrocyclone-table system with other fine-coal processing systems; and application of the hydrocyclone-table system in fine-coal circuits. The data show that the table actually compensates for the shortcomings of hydrocyclone and makes a combination table-hydrocyclone system attractive, particularly in those cases where fine pyrite is one of the major contaminants.

Jan 1, 1973