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By Patrícia de Fátima Rodrigues

Neste trabalho, a técnica de ensaios de torção a quente foi utilizada na simulação física do processo de laminação a quente do produto fio-máquina. Foram realizados ensaios em dois tipos de aços, a saber, um aço baixo carbono (BC) e outro aço ultrabaixo carbono (UBC). A realização dos ensaios de torção a quente, sob condições próximas ao processamento industrial, ou seja, utilizando parâmetros de processo como taxa de deformação, temperatura e tempo entre passes, fornecidos pelo fabricante do laminador, possibilitou evidenciar os mecanismos de amaciamento destes aços. Foram obtidas as curvas de escoamento para as condições propostas e realizadas análises metalográficas para avaliar as microestruturas resultantes. A partir dos resultados obtidos pode-se concluir que ambos os aços apresentaram bom desempenho na laminação do fio-máquina. Em particular, o aço ultrabaixo carbono mostrou-se capaz de suportar as condições de processamento impostas nas simulações, o que torna viável sua possível aplicação no mercado de produtos de aços longos.

Aug 16, 2017

By Clarence M. Haight

The general practice in drill sharpening shops, of which descriptions have been written, is about as follows: The bit is heated to 1600" to 1900°F. Then when forged to the proper shape and size in the sharpening machine, the steel is allowed to cool; it is then passed to a hardening furnace where only the end is heated to about 1450" F., and then quenched in cold water, brine, or in brine with oil on top.

Jan 1, 1922

By William Rodrigues Soares

Este trabalho apresenta um estudo sobre a influência de diferentes ciclos de tratamentos térmicos sobre a microestrutura e propriedades mecânicas de dois aços (A e B) especificados pela norma API 5CT. O aço B tem um conteúdo de elementos de liga maior que o aço A. Caracterizou-se de forma qualitativa e quantitativa as microestruturas por meio de microscopia óptica e eletrônica de varredura. As propriedades mecânicas foram medidas por meio do ensaio de tração. As amostras do aço A submetidas ao resfriamento ao ar calmo e forçado apresentaram uma maior fração volumétrica do constituinte MA (martensita/austenita retida) em relação ao aço B e o aumento da taxa de resfriamento aumentou a quantidade de MA para os dois aços, o que resultou em um aumento no limite de resistência a tração para os aços A e B. As amostras que foram resfriadas ao ar calmo e ao ar forçado apresentaram menores limites de escoamento que as amostras temperadas e revenidas. Este resultado pode ser explicado pela presença de bainita e do constituinte MA nas amostras resfriadas ao ar calmo e ao ar forçado cuja presença gera uma maior densidade de discordâncias.

Aug 16, 2017

By William P. Shinn

Jan 1, 1881

By W. M. Cross

Bubble attachment time measurements for the rare-earth phosphate minerals monazite and xenotime were made as a function of oleate concentration, sodium fluoride addition, and temperature. Results indicate that the rare-earth phosphates behave similarly to other phosphate minerals, notably collophanlte and fluorapatite, which have been studied previously. The addition of sodium fluoride yielded a modest decrease in bubble attachment time with fluoride additions below the apparent fluoride surface precipitation point, while at fluoride additions greater than the apparent precipitation point a significant decrease in attachment time occurs. Increasing the temperature or the system gave a slight decrease in bubble attachment time in the absence or sodium fluoride. With sodium fluoride addition and below the apparent fluoride surface precipitation point, an increase in temperature actually increased the attachment time. For sodium fluoride additions above the apparent fluoride surface precipitation point, a temperature increase significantly decreased the attachment time.

Jan 1, 1989

By Josh Swank

Albert Einstein once said, ?the important thing is not to stop questioning.? In the mining industry, a lack of inquisitiveness may lead to a blissful ignorance but it certainly will not increase efficiencies. While one may claim necessity is the mother of invention, questioning and analyzing how methods and systems can be improved is the catalyst to discovering necessities. Understandably, when working in the middle of Canada?s oil sands, where trucks operate around the clock every day of the year, it is nearly impossible to pull the nose from the grindstone long enough to provide thorough analysis. But, fortunately, some manufacturers/inventors have assisted by examining the process and the ensuing headaches within this application.

Jan 1, 2013

By C. C. Hustwit

The U.S. Bureau of Mines formulated a new mathematical model to characterize iron oxidation. The new model is intended to replace the currently used model, recommended by the Environmental Protection Agency (EPA), for most acid mine drainage (AMD) treatment applications. The new model was evaluated in a series of five synthetic AMD treatment tests. The initial ferrous iron concentrations ranged from 800 to 2,400 mg/L. In these tests, the Bureau model underpredicted the measured ferrous iron oxidation rates by a range of 3.24 to 8.03 pct. This was considered to be in close agreement after consideration of experimental error. The model proposed by the EPA was also evaluated using the same test data. The EPA model underpredicted the oxidation rates by a range of 77 to 100 pct in four tests and overpredicted by 19 pct in one test. The model formulated by the Bureau expresses that the rate of iron oxidation is a function of a treatment system's oxygen transfer efficiency and is independent of ferrous iron concentration when treated to near-neutral pH's. A new test method for evaluating oxygen transfer in flow-through reactors is also described.

Jan 1, 2010

By Henrique Paier Milanez

À medida que os depósitos minerais de alta qualidade vão se exaurindo e a contínua busca por menores custos operacionais aumentando, as rotas de beneficiamento de minério tornam-se mais complexas, gerando custos de capital cada vez maiores. Dessa forma, surgem desafios não somente para a redução desses custos, mas também para validação do dimensionamento dos equipamentos, teste das lógicas de controle, treinamento operacional e redução do tempo de start-up. No presente trabalho é realizada uma breve revisão bibliográfica sobre o atual cenário de simulação de processos na indústria mineral e é mostrado como essa tecnologia se encaixa em todas as etapas do desenvolvimento de projetos. Especificamente, são apresentados estudos de dimensionamento de linhas de processo e dimensionamento de bombas centrífugas em casos técnicos em que o software IDEAS foi utilizado como ferramenta de simulação dinâmica para validação do processo, reduzindo o impacto financeiro em etapas posteriores. Como exemplo dos resultados das validações, mais de 40 bombas tiveram seu dimensionamento reavaliado e mais de 10 tubulações tiveram seus diâmetros revisados. Os resultados observados corroboram o grande potencial tanto da ferramenta computacional, quanto da simulação de processos de modo geral.

Jul 30, 2018

By Mario Samamé Boggio

El presente texto describe las condiciones en que se desarrollaba la industria extractiva antes de la dación del Código. Asimismo se revisa la política económica y social en sus aspectos económicos de la minería.

Nov 1, 1954

By E. L. McHugh, J. M. Girard

This paper discusses the results of two recent case studies in which high-tech prototype instruments were used. The first case study describes the results of a ground-based hyperspectral imaging tool used to map the geology of an open-pit mine highwall. The second case study outlines the use of interferometric synthetic aperture radar and how this type of radar can be used in a variety of geotechnical situations. These case studies are part of an on-going research project at the National Institute for Occupational Safety and Health’s (NIOSH) Spokane Research Laboratory. The project objective is to implement engineering controls and design methods in order to reduce the number of injuries and fatalities associated with slope failures at mining operations. Project personnel are hopeful that these new developments in technology will lead to better geotechnical monitoring and design in slope stability and other important areas of rock mechanics.

By Dilip I. Patel, Jesus Schabib, W. Allen Mawr, Daniel A. Louis

East Side Access (ESA) will extend Long Island Rail Road into midtown Manhattan via 11 km of tunnels, a new terminal station and associated rail support facilities. The hard-rock tunneling in Manhattan will traverse under Park Avenue and some of the most historically and commercially significant real estate in the world. The soft-ground tunneling in Queens will traverse beneath Amtrak’s Sunnyside Yard and the Harold Inter locking, the busiest rail interlocking in North America. This paper details ESA’s program-wide geo-instrumentation monitoring system for obtaining, processing and presenting all geotechnical monitoring data. Data streams will be real-time, such as from automated total stations, and manually read, such as from optical survey instruments and handheld data loggers. All data will be input into a web-based Geo-Instrumentation Data Management System, which will be accessible to project stake holders via ESA’s intranet or via the Internet using remote access controls.

Jan 1, 2007

By Marling J. Ankeny

MINING research in the U. S. today is indeed complex, whether it involves the Government, a small private concern, or a large one. And it promises to become more so, despite great advances already made in developing equipment and technology. The U. S. Bureau of Mines is committed to place greater emphasis on mining research as expressed in a recent policy statement to Congress on the "Long Range Minerals Program," by Secretary Fred A. Seaton, quoted above.

Jan 1, 1958

By H. V. Makar

The Bureau of Mines successfully demonstrated, on a pilot plant scale, a sodium sulfate (Na2S04) refining process for removal of copper from molten ferrous scrap. Previous tests established technical feasibility on a bench scale for achieving low copper concentrations and determining the principal factors controlling process efficiency. The pilot plant study involved a 1-ton arc furnace for melting ferrous scrap and a 1-1/2-ton treatment ladle. Results of these tests showed that copper removals obtained in laboratory tests (approximately 40 relative percent copper removal with 10 weight-percent surface addition of sodium sulfate) could be achieved on the pilot plant scale when excess carbon was added with the sodium sulfate compacts. Data were obtained on temperature losses and carbon consumption related to Na2SO4 treatment.

Jan 1, 1974

By Zhang Jiaju

For the highrise buildings with deep foundstion of irregular plane shape, an appropriate calculate model to the heave of foundation soil after excavation is proposed and studied using analytic method and FEM (Finite Element Method) respectively to provide an effective way for solving this kind engineering problem. Also combined with the practice of construction deep foundation of Capital Mansion, calculation of the heave of foundation soil after excavation is given. Compared these results from above two methods with the results measured in situ, it is conformal on the whole, and the results by FEM are much closer with the measured.

Jan 1, 1991

The seventh Annual RMCMI Mine Rescue Evaluation was held during the 1998 Institute convention at the Silvertree Hotel, in Snowmass Village, Colorado. The Mine Rescue committee, co-chaired by Becki Boam and Elliott Tsosie, is one of 18 committees of the Institute. In 1998 a record number of 10 teams participated in the program. The teams were from the four western states of Montana, New Mexico, Texas and Wyoming and were comprised of about eight members each. Teams participating were BHP-La Plata Mine, BHP-Navajo Mine, BHP-San Juan Mine, all from Farmington, New Mexico; Bridger Coal Company, Rock Springs, Wyoming; General Chemical, Green River, Wyoming; Jacobs Ranch Mine, Gillette, Wyoming; Powder River Coal Company-North Antelope/Rochelle, Gillette, Wyoming; Sabine Mining, Hallsville, Texas; Solvay Minerals, Green River Wyoming, and Western Energy-Colstrip, Montana. The professional evaluators provided challenging scenarios for over 90 participants and many observers. The evaluators were: Art Saenz and Tom Bass of Western Environmental Associates, Keith Mitchell and Jim Jennings of Emergency Services Detail; Mary Bailey of Mary Bailey Associates; and John Peleaux of Innovative Access. Teams are not given advance warning of what the problem will entail. They are provided the necessary details when they arrive at the scenario location and work to resolve the problem in an effective and efficient manner. [ ] Seven participants made up each team with an . eighth member as an alternate. Team trainers and other mine personnel traveled with the team from scenario to scenario providing support and encouragement. The teams were presented with four scenarios each day, involving High Angle Rescue, Low Angle Rescue/Medical, Hazmat, and Confined Space. All of the victims, except for one, were provided through the cooperative efforts of the Snowmass Fire Department, who also assisted with providing several evaluators. Snowmass Fire Department is to be commended for providing over 20 victims/evaluators each day to facilitate the evaluations. Training sessions were held Friday afternoon and Saturday evening to help the teams prepare for the scenarios. A swap meet was held Friday evening for teams to trade hats, shirts, belt buckles, stickers, etc. All mine rescue participants and spouses and registered families attended the Bar-B-Q on Sunday evening followed by an adult dance. [ ] Front row: Ray Blaisdell, Solvay; Gary Rasmussen, General Chemical; Spencer Thompson, Sabine; Jack Ervin, Western Energy. Back Row: Ken Kellywood, BHP Navajo; Jonathan Sorrell, BHP LaPlata; Elton Stanton, Jacobs Ranch; Travis Roy, Powder River Coal; Ron Neff, BHP San Juan; Steve Whaley, Bridger. Sponsors who contributed to the 1998 program financially were: Blue Mountain Energy, (Deserado Mine); Flanders Electric Motor Service, Inc.; Rocky Mountain Electric Motors, L.S.; and Western Environmental Associates. Glass trophy cups, with an etching of a Mine Rescue figure and the RMCMI Logo on cherry wood bases, were presented to the 10 team captains at the Monday Mine Rescue Awards Breakfast. Eight of the ten teams had a proficiency level of 3 and 2 teams achieved a proficiency level of 2.

Jan 1, 1998

By P. M. Pettit

Hydrologic investigations at Gold Quarry began in 1989 and continued through 1991. Hydro-stratigraphic units include Tertiary sedimentary rocks, Paleozoic siltstones and carbonates. These units display complex and variable aquifer parameters as a function of faulting and hydrothermal alteration, creating compartmentalized hydrologic domains. Testing has included step-tests, spinner production logs and constant discharge tests. Two Three-Dimensional Finite Element Models have been developed, one for optimizing the pit dewatering system and the second for predicting regional impacts of dewatering. Aquifer testing and long term pumping have been used to calibrate both Finite Element Models.

Jan 1, 1992

By Luiz Gabriel da Silva Nascimento

Foi fabricada uma matriz hipoeutética de Al-2%Ni e adicionado nela concentrações de 0,5; 1,0; e 1,5 % de nanotubos de carbono de paredes múltiplas (NTCPM). A fabricação do material estudado aconteceu por fundição e resfriamento unidirecional brusco originado grãos predominantemente colunares. Os ensaios mecânicos mostram que concentrações maiores de nanotubo na matriz provocam acréscimo na propriedade mecânica e que em áreas mais distante da base extratora de calor a microdureza aumenta. Na amostra que contém 1,5% de nanotubos o valor da microdureza em áreas da posição P1 distante 5 mm da interface metal/molde é aproximadamente de 120 HV, já em áreas da posição P5 distante 45 mm, se aproxima de 210 HV. A resistência a tração é influenciada pela adição de NTC. A matriz possui uma resistência a tração de 64 Mpa, enquanto que a adição de 1,5% de NTC eleva esse valor para 135 MPa.

Aug 17, 2017

By William H. Pelton

The presence of high-grade massive sulphides near York Harbour, Newfoundland has been known since the turn of the century. In the early 1900's a small, massive-sulphide deposit was worked by conventional hand methods and yielded about 100, 000 tons of high grade copper-zinc ore. Since that time, a number of mining companies have held options on the property and an exploration adit was driven along the fourth level of the original mine. Underground drilling revealed several additional massive sulphide lenses in the range of 10, 000 to 60, 000 tons (Fig. 1). The problem facing Long Lac Mineral Exploration Ltd. when they undertook an option on the property in 1969, was to outline any possible extensions to the known sulphide lenses which were outside the reach of underground drills and to search for new ore deposits which might double the known reserves into a feasible project for development. GEOLOGY AND PHYSICAL PROPERTIES: The geology is typical of many massive sulphide deposits within volcanic rocks in the Canadian Shield. The sulphide pods appear to occur along a complex andesite-basalt contact. Identification of the two volcanic types is difficult since they are almost the same colour. The most direct means of identification is by the slight difference in their magnetic susceptibilities. Pyrite, chalcopyrite and sphalerite are the main minerals in the sul¬phide lenses. The ore is massive, differing in density from the host rock by at least 1.0 gm/cc. There is little pyrrhotite or magnetite associated with the sulphides, so there is no appreciable difference in magnetic susceptibility between the sulphides and the basalt. Also, there is no alteration halo around

Jan 1, 1971

By Yanan Zhang, Hongwei Deng, Feng Gao, Bo Ke

Recently, liquid carbon dioxide (L-CO2) blasting technology has attracted attention due to its good fracturing effect and safety performance, especially in coal seam permeability improvement. This paper analyzes the blasting effect of L-CO2 based on experiments and studies the fracturing mechanism from the perspective of stress wave action via theoretical analysis and peridynamic simulations. The results indicate that L-CO2 blasting achieves a good fracturing effect without forming a crush zone, and the loading rate and strength of the stress wave are key factors.

Jan 19, 2022

By K. E. Tame

An alkaline leaching procedure for recovering uranium from a submarginal 0.1 percent Ug Og calcareous carnotite ore from the Shiprock , N. Mex . , area was investigated . A recovery of 72 percent of the uranium was attained in a preliminary test embodying the commonly accepted practice of ( 1 ) alkaline leaching at 90° C , ( 2 ) multiple stage filtration and washing for recovery of a clear pregnant solution , and ( 3 ) caustic precipitation of uranium as sodium diuranate , with recycle of the barren solution to the leaching and washing circuits . Ion exchange resins were used in a second , less orthodox test that comprised ( 1 ) sodium carbonate leaching of minus 10- mesh ore at 90 ° C to dissolve the uranium , ( 2 ) filtration to recover the leaching reagent for reuse , (3 ) recovery of the uranium- bearing solution in the filter cake as a pregnant slime slurry by repulping of the filter cake followed by a sand- slime separation and countercurrent decantation (CCD ) washing for rejection of the sand fraction , (4 ) recovery of the dissolved uranium from the pregnant slime slurry by resin- in- pulp (RIP ) , ( 5 ) elution of the uranium from the resin with a solution of ammonium chloride acidified with hydrochloric acid , and (6 ) precipitation of the uranium with ammonia gas . About 83 percent of the uranium was extracted from the ore and 95.5 percent of the dissolved uranium recovered by ion exchange . Improved laboratory results were obtained using the RIP process , but larger scale tests would be necessary for economic evaluation of the two processes .

Jan 1, 1964