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By Eldon L. Abbott, Rebecca K. Bolan

The Florida Department of Transportation, Florida’s Turnpike Enterprise is studying the feasibility of a 1128 meter (3,700 foot) vehicular tunnel to provide direct access for Port of Miami traffic to/from I-395, I-95, SR-836 (Dolphin Expressway) and Miami International Airport. Both Bored and Immersed Tube tunnels were evaluated and re-evaluated for constructing two, two-lane, 11.9 meter (39-foot) diameter tunnels beneath the Main Shipping Channel lying between Watson Island and the Port of Miami on Dodge Island in Biscayne Bay, Miami, Florida, USA. Bedrock Geology of South Florida is predominately very permeable, vuggy limestone with sand seams and occasional voids. Groundwater inflows in deep cut-and-cover excavations, tunnel buoyancy, grouting, maintenance of Port operations and potential/possible environmental impacts to Biscayne Bay were significant issues.

Jan 1, 2005

By Bryan de Barros Soares

O aço carbono é um material amplamente empregado na indústria petrolífera devido sua elevada resistência mecânica e baixo custo. Entretanto, este material não possui boa resistência à corrosão. Neste contexto a predição da taxa de corrosão é de extrema importância para estimar a durabilidade desses materiais. Atualmente isto é feito com base em dados de ensaios de perda de massa em um único tempo de imersão, estimando-se a taxa de corrosão. Contudo, para converter os dados de perda de massa em taxas de corrosão é imprescindível que os ensaios sejam conduzidos em diferentes tempos de imersão e que haja linearidade entre perda de massa e tempo. Neste trabalho a corrosão do aço carbono em meios saturados com CO2 foi investigada através de ensaios de perda de massa em três tempos de imersão diferentes, com o objetivo de avaliar essa linearidade. Dos quatro meios corrosivos estudados, um não apresentou linearidade entre PM e tempo de imersão, sendo portanto incorreto extrapolar os dados para taxa de corrosão. Os resultados comprovaram que a extrapolação de dados de PM para taxas de corrosão não pode ser aplicada sem uma prévia verificação da linearidade entre perda de massa e tempo de imersão.

Aug 16, 2017

By R J. Merchant

The Hauraki goldfield is located east of Auckland in the North Island of New Zealand. It includes Great Barrier Island, the Coromandel Peninsula and the Coromandel and Kaimai Ranges as far south as the town of Te Aroha and south east to Te Puke. It has a total north-south extent of about 180 km and an area of 3000 km2. The goldfield is the most productive in New Zealand, and while production at present is negligible, the area has undergone continuous exploration over the last seven years.

Jan 1, 1984

By Dave Ragland

The SDSU tunnel and underground station are the first of these type facilities to be constructed by the Metropolitan Transit Development Board. Because there is no previous experience, and because tunneling activities are associated with some risk, he MTDB has undertaken a very proactive and wide reaching program to identify and control risks during construction. Finally, because the tunneling activity and underground station is on the San Diego State University, MTDB is working closely with their staff to identify construction impacts and mitigation’s, and thus ensure a quality project for both agencies.

Jan 1, 2001

By Pelin Altinkaya, Maria Leikola, Jussi Liipo, Mika Haapalainen, Mari Lundström, Eero Kolehmainen

With decreasing ore grades, the tailings of mining operations are becoming of increasing interest as metal-containing secondary raw materials. The objective of the current work was to investigate chloride leaching of gold, copper, cobalt, nickel, and zinc present in the flotation tailings. In the current study, the effect of cupric ion as an oxidant (0–50 g/L) and NaCl (150–250 g/L) on metals extraction was investigated. The other parameters, such as pH (1.8), temperature (95 °C), solid/liquid ratio (25%), oxygen feed rate (1200 mL/min), leaching time (24 h), and stirring rate (950 rpm), were kept constant. Gold dissolution rate was shown to increase with increase in cupric ion concentrations up to 50 g/L. Also, increase in NaCl concentration up to 250 g/L increased gold extraction. Majority of the copper present in the flotation tailings could be dissolved with all the all solutions investigated. The other base metals, cobalt, nickel, and zinc extractions were also shown to increase with increase in the cupric ion and sodium chloride concentration. However, even in the absence of cupric ion addition (t = 72 h, 250 g/L NaCl), the final extraction of Cu, Ni, Zn, Co, and Fe increased up to 98, 93, 83, 76, and 80%, respectively. This shows the power of inherently originating oxidants present in the tailings. Furthermore, the solid analysis of the leach residue indicated that leaching the flotation tailings in pure NaCl may result in partial gold dissolution. The results demonstrate that significant amount of metals present in the tailings could be extracted even with only NaCl as added chemical in the presence of oxygen feed, oxidizing agents originating directly from the raw material. This can provide an advantageous cyanide-free method for extraction of metals from very low-grade tailings with low chemical consumption.

By François Girard

La zone 1 de la mine Doyon (zone altérée), se situe à l?extrémité sud de la mine et est constituée d?une série de veines étroites à fort pendage et ayant des épontes de très faible résistance. Les épontes supérieure et inférieure ont des valeurs de RQD variant de 0 à 20 lors que les valeurs de RQD de la zone minéralisée se situent entre 20 et 40. Le minerai de la zone 1 s?étend sur environ 300 m de long et sur 900 m de profondeur avec des épaisseurs variant entre 2 et 15 m. Des méthodes de minage long-trous y sont utilisées avec des accès longitudinaux ou transverses selon l?épaisseur de la zone minéralisée. L?exploitation de la zone 1 a débuté en 1991 et plus de 1,7 millions de tonnes auront été extraites à la fin 2008. Plusieurs techniques y ont été testées que ce soit au niveau du développement ou du minage afin d?améliorer la sécurité des travailleurs, de réduire la dilution des chantiers et d?en augmenter la récupération. Différentes modifications ont été apportées aux dimensions et orientations des galeries, aux patrons de forage, aux techniques de sautages, au support de terrain, à la séquence de minage et aux méthodes de remblayage. Le texte suivant élabore sur plusieurs approches utilisées lors du minage de la zone 1.

Feb 1, 2008

As the 2009 George Fox Conference neared its conclusion, Arthur Silber, project chief of the Mass Transit Tunnel (MTT) project was able to pull away from the constant buzzing of his Blackberry long enough to give a short presentation and a significant piece of news to the record 318 attendees at the Graduate Center, City University of New York regarding the MTT project. ?As the former administration (The Bush administration) was leaving office, we were told that Congress was notified of the FTA?a (Federal Transit Authority?s) intent to issue final design construction approval to us,? Silber said of recent advancements concerning the $7.2-billion dollar project. It will add passenger rail service from New Jersey to New York City as part of the Access to the Region?s Core project in the form of the Trans Hudson Express Tunnel (THE tunnel). ?That 10-day waiting period ended yesterday (Jan. 26).? In days leading up the Fox Conference, those involved in the tunneling industry, and the MTT in particular, had a lot to be optimistic about. The MTT received environ-mental approval on Jan. 14 (see page 9) and, with the acceptance of the final design, the multi-billion dollar project moved that much closer to a ground-breaking ceremony. So close, in fact, that before leaving his office for the conference, Silber posted the contract documents and plans for the Manhattan Tunnel project online at www.arctunnel.com (an indepth look at the project from Silber is on page 22). While many were interested in the progress of the project, Silber also spoke about the new plans for the cavern complex at the New York Penn Station expansion. The original plans called for two lines that would come into a large cavern complex with a north and south cavern to access the trains. After numerous core samples were taken from the streets of Manhattan, it was deter-mined that this design was not feasible and changes were made that will include a deeper cavern under Sixth Avenue, with 14-m (45-ft) of cover with a 30-m (96-ft) wide cavern that resides entirely under 34th Street. The cavern was also moved 20 m (60 ft) to the west to remain at least 61 m (200 ft) away from New York City Water Tunnel #1. The new design will include three-over-three track arrangement. The mezzanine will be 46 m (150 ft) below street level at 8th Ave, Silber said.

Jan 1, 2009

By John Drew Ridge

Tables showing world trade in metallic mineral raw materials during the years 1953 through 1957 have been prepared for the following twenty-one commodities: alumina, aluminum, bauxite, chromite, copper concentrates, partly refined and fully refined copper metal, iron ore, pig iron, iron and steel (simple shapes), lead concentrates, lead metal, manganese ore, mercury metal, nickel ore, concentrates, and matte, nickel metal, raw pyrites, sintered pyrites, tin concentrates, tin metal, zinc concentrates, and zinc metal. In each instance, the amounts given by the importing country were used except when statistics from the importing nation were lacking, incomplete, or misleading. To show the considerable divergence between importing and exporting country totals for the same years, the complete mercury table is given and, in parallel columns, shows the comparable tonnages of importers and exporters. Tables for the other twenty commodities are presented in summary form. The data of the concentrate tables are used with those of the corresponding metals as a basis for a discussion of trade in concentrates versus trade in metals. The data of all twenty-one tables provide the basis for testing the thirteen rules governing international trade in metal raw materials which I first published in Mining Engineering for July 1955. Because the 1953 through 1957 data are far more complete and considerably more extensive than those on which the 1955 rules were based, it was found possible to deduce five additional rules and to modify three of the original thirteen appreciably. The full text of the eighteen rules is given.

Jan 1, 1960

By Percy Mamani, James Atalaya

"A fines del año 2012 se inicia el Proyecto de cambio en la Gestión de seguridad en la UP Animon de la Cía. Minera Chungar SAC, estableciendo nuevas estrategias para controlar la frecuencia como también la ocurrencia de nuevos accidentes. En el año 2014 no tuvimos la ocurrencia de accidentes mortales, mejorando la imagen de la empresa en la corporación y a nivel nacional. Aun se tiene ocurrencia de accidentes leves e incapacitantes, para lo cual debemos establecer nuevas y mejores estrategias. La estructura de nuestro SGI Volcan se basa en 4 pilares, con soporte de las 9 herramientas temáticas, los 12 Riesgos Críticos y Normas legales: Ley 29873, DS-005-2012-TR y DS-024-2016-EM. "

Sep 1, 2017

By G. W. Jones

One of the major activities of the Bureau of Mines is the promotion of safety in mining and other industries, In this connection, the Bureau determines the explosion hazards' of combustible gases, vapors, and solids and investigates means of controlling and preventing explosions. Many dangers are likely to confront men who must enter a building immediately after it has been damaged. Rescue workers must watch constantly for common gases and vapors that may be present in dangerous concentrations in and about demolished, buildings. Fuel gas is the most common source of danger, although refrigerants, gases from furnaces, flues, fires, sewers, and industrial processes, and gas from bomb, explosions in confined places also constitute definite hazards. To rescuers and trapped casualties, these gases offer the hazards of (1) explosion, (2) toxic effects, including asphyxiation and death, and (3) displacement of air so that the oxygen content of the atmosphere is reduced to or below the danger level.

Jan 1, 1944

By P. G. Guest

MANY of the gases and vapors used in anesthesia form explosive mixtures with oxygen or air. Sources of ignition for these mixtures always have existed in operating and anesthetizing areas. When ether was first introduced, candles,5 gaslights, and coal stoves caused fires and mild explosions of the vapor-air mixtures. Today the chief causes of ignition are electrical. Fires and explosions are still much too frequent; and, because many of the mixtures are rich in oxygen, the explosions sometimes are very violent. Obvious sources of ignition, such as electric-power sparks and arcs in open motors, switches, and receptacles, as well as exposed incandescent wires and hot plates, usually are recognized by hospital personnel and corrected. A source of ignition that is not so obvious to many is static electricity. Until quite recently the presence of this hazard in a large majority of anesthetizing areas was not even suspected. However, numerous explosions-many of them fatal to patients-have been attributed, with good reason, to sparks from static electricity.

Jan 1, 1953

By G. R. Hopkins

"Refiners are generally considered solely as fuel producers, but actually they also comprise a group one of the largest consumers of fuel. For example, during the year 1929 the refineries-burned 51,544,000 barrels of oil as fuel, or the equivalent of over 5 per cent of the crude oil processed in that year. In addition enough other fuels - coal, natural gas, refinery or still gas, and petroleum coke - were utilized to raise the total fuel consumption based on B. t. u. equivalent to more than 10 per cent of the heat value in the total crude oil run to stills. Refineries utilize fuel chiefly as the heat-forming element distillation, but also under-boilers in the formation of steam used in refining, for the heating of buildings, and in the generation of electricity.In the early days of refining, the problem of fuel utilization and fuel economy was of scant importance to the refiners. Margins of profit were comparatively high and the major portion of the operatros1 attention was directed toward increasing their throughput. However, the keen competition that has prevailed in the refining industry over the past five years or more has taught the refiners that their expenses, one of the largest items of which is the cost of fuel, must be curtailed. Thus in 1925 the refiners used an average of 829,000 B. t. u. to refine a barrel of crude oil, wheras by 1929 this average had been reduced to 639,000 B. t. u., a decline of 23 per cent (see fig. 1)Since 1925 oil has ranked first as a refinery fuel (see fig. 2). The use of natural gas increased during 1926 and 1927 but declined in 1928 and 1929. On the other hand, the use of refinery gas has grown rapidly in importance. Coal has shown a steady decline in use at refineries since 1925. Petroleum coke has never supplied more than a very small fraction of the total fuel requirements, although there has been a steady increase in its use."

Sep 1, 1930

The interaction of flotation collectors with sulfide minerals takes place at the solid - solution interface. The electrochemistry of the processes which affect this interface are discussed. The interaction of xanthates with sulfides is an electrochemical process, xanthates being electro-oxidised to chemisorbed xanthate and dixanthogen. The role of oxygen is to provide a cathodic process to allow the anodic oxidation to occur. The hydrophobic condition of the mineral surface is brought about by the presence of the oxidised xanthate species. The action of reagents which can activate or depress the flotation of sulfides is discussed briefly.

Jan 1, 1971

By R. W. Huber

A consumable-electrode arc-melting furnace was constructed at the Bureau of Mines Physical Metallurgy Laboratory, College Park, Md., for the production of uncontaminated titanium and titanium-alloy ingots. The furnace was designed to allow for evacuating to very low pressures and back filling with helium and argon mixtures for melting at or near atmospheric pressure. Vacuum melting at a few millimeters pressure was also used with a mixture of helium and argon gas sweeping the crucible. For research purposes a 25- to 30-pound ingot, 4 inches in diameter by 15 inches in length, was selected to provide, enough 1/2-inch plate for extensive tensile and impact testing of standard size specimens. Enough plate was also provided for testing by other Government laboratories. The homogeneity of several alloy ingots was determined, and excellent results were obtained. By using a large electrode-to-ingot-area ratio and high currents or power inputs to the arc furnace rather uniform ingots were routinely prepared.

Jan 1, 1957

By Kenneth R. Johnson

El presente trabajo describe los factores que incluyen el proceso de planeamiento de la mina. Dado el tamaño y forma de los minerales encontrados en un mina de Estados Unidos, se inició el sistema de "open it" o minas a tajo abierto. Posteriormente, este sistema permanecería sin cambio alguno hasta mediados de 1930, donde se inició el uso de unidades de transporte montadas sobre llantas y se mejoró el proceso de operación de "open it". El planeamiento de mina a cielo abierto se basa en tres elementos: suficiente mineral, evaluación a largo plazo de la operación y las características del equipo de carguío y transporte. Asimismo, la vida de una mina a tajo abierto se divide en tres períodos: operación inicial, período normal de producción y período final de producción, considerando que dicho planeamiento se realice en las operaciones de este período.

Aug 20, 1963

By C. Machio

This paper reports the results of a study to determine the effect of process control agent (PCA) on the characteristics of Ti-Mg powders during milling. It has been shown that a 2% increase in PCA content leads to up to a 40% increase in yield of the milled powder but reduces the kinetics of the mechanical alloying process. The introduction of 4% PCA decreases the mean powder particle size by up to 30%, whereas 6% PCA increases the mean particle size by up to 230%. The characteristics of the milled powders will be discussed in relation to the role of PCA in the milling process. Keywords Titanium?magnesium, mechanical alloying, PCA.

Jan 1, 2011

Drilling in the south of the Rapahoe Sector at Greymouth Coalfield has demonstrated the existence of thick coal seams in the upper Rewanui Member. Seam correlation is handicapped by complex lithostratigraphy and laterally variable geophysical log profiles. An integrated investigation of coal measure stratigraphy, coal petrology, and proximate analyses, suggests a feasible model whereby most of the major seam intersections belong to a single horizon. Coal properties vary laterally in response to original swamp conditions, which are believed to have ranged from well-drained to ponded. A new model of peat accumulation is proposed for the northern Rapahoe Sector, whereby Upper Rewanui peat accumulation occurred on a flood plain between the levees of a major south southwest-flowing fluvial system in the east and the toe of a western alluvial fan.

Jan 1, 1985

By A. Lewis, J. Zachwieja, M. Widell, P. Zhou, W. W. Geissler, M. Svensson, A. Movahedi, H. Nordberg

Flotation collectors for sulfide minerals has been traditionally based on xanthate, thiophosphate, thiophosphinate and thiocarbamate, all derived from sulfur chemistry. Tecflote™ is a new family of patented collectors based on nitrile chemistry which can supplement or replace thiol collectors, depending on the ore types. A steep grade-recovery curve typical of Tecflote™ collectors was observed when using Tecflote™ as the main collector for the rougher and cleaner steps allowing a better recovery compared to current thiol collectors while maintaining the desired grade. Additional recovery increase has also been observed by the addition of scavenger steps using Tecflote™ collector in combination with current thiol-based collector. The selectivity seen in the lab is transferred to full scale trial and is clearly seen in the rough flotation where the increase in the rough concentrate grade of 5% after pumping Tecflote S11 directly into the tank cell. The mechanisms for Tecflote’s selectivity towards sulfides are currently under investigation and will be discussed. Results of TOF-SIMS analysis will be presented, demonstrating the collector’s selective affinity to different mineral surfaces in flotation. INTRODUCTION The history of collectors used today started in 1882 when Zeise first made xanthates. It was first used in flotation in 1925 – Cornelius Keller’s first patent (Fuerstenau, Jameson, Yoon, 2007). Between 1928 and 1930 American Cyanamid filed 7 patents for dithiophosphate, including flotation and chemical synthesis of the reagent, the first of which was filed by Christmann in 1928 (Christmann, 1933). Synthesize of thionocarbamates for mineral flotation was filed in 1954, by Dow Chemical Company (Harris, 1954). Now that the head grades have been declining over the last decades the need to find more selective collectors to extract difficult and complex ores has pushed the industry to look at different chemistries. Thiol collectors standard to the industry rely on the sulfur in the collector molecule to bond to the mineral surface. The electronic property of this group is modified by the adjacent chemical groups, such as additional S, P or N have the effect of changing the selectivity of the collector (Wills & Finch, 2016). In the case of xanthate the length of the hydrophobic group also has an effect on the selectivity with some minerals such that the ethyl xanthate is more selective against pyrite and pyrrhotite than the long chain xanthates (Wills & Finch, 2016).

Jan 1, 2019

By S. James Campbell

Ladies and Gentlemen: Never in the history of our mining industry has the emphasis on public relations been accelerated as much as it has in the last few years. Knowing of your keen interest in this subject I consider it a great privilege that your program committee has asked me here to discuss the crushed stone segment of our industry approach to this important part of our daily business lives. As you are aware, crushed stone operations are present in almost every segment of the country wherever aggregates for construction projects are required. The tonnage of crushed stone produced is second only to sand and gravel - another source of aggregates - and this together with sand and gravel amounts to over half of the tonnage of all mined products in the United States. What is unique about this industry that will be of interest to all of you in analyzing how they have approached Public Relations? The fact that it is so wide-spread is of course obvious, but perhaps a more significant nature of this segment of the mining industry that has brought it more in the limelight of public interest and on a larger scale is the location of a large part of the quarries quite close into the urban area and population centers where you have the greatest demand for aggregate products.

Jan 1, 1969

By J. Gonzales, C. Chávez

Este estudio se basa en un probable nuevo descubrimiento de un yacimiento de Au, en las rocas del volcánico Llallahui (Grupo Tacaza – Terciario Medio a Superior), que podría estar ligado a la ocurrencia de yacimientos epitermales de Au del sur del Perú. Se trata de un yacimiento epitermal de baja sulfuración, emplazado en autobrechas y tobas donde mediente los análisis químicos de los muestreos realizados se determinó valores de leyes en Au 0,10g/TM a 0,81g/TM, estimandose recursos inferidos de 70MT @0,10-0,80 g/t de Au, lo cual convierten en un prospecto de gran potencial.

May 1, 2008