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By Jiangtao Li, Zhongwei Zhao, Xingyu Chen, Xuheng Liu

In tungsten ion-exchange process, excessive sodium impurity enters into ammonium tungstate solution. However, the Na content of the final ammonium paratungstate (APT) product must be strictly controlled. Consequently, it is necessary to remove Na from the ammonium tungstate solution during processing in order to obtain the required purity of APT. In this study, porous Na specific absorbent, Na1+xAlxTi2−x(PO4)3, is used to remove Na from the ammonium tungstate solution. Through experiments, the effect of reagent concentration of Na1+xAlxTi2−x(PO4)3, reaction time, reaction temperature and Na concentration on the Na removal were investigated. The results showed that under optimal reaction conditions of reagent amount of NATP 1.0 times of theoretical amount, reaction temperature 25 °C and reaction time 15 min, the Na removal from commercial (NH4)2WO4 solution can reach 98%. Na1+xAlxTi2−x(PO4)3 has a good applicability to different Na+ concentrations. The obtained APT product reaches the national standard purity of zero level.

Jan 1, 2014

By A. P. Schissler

Mining has several characteristics, uncommon in other business sectors, which pose additional challenges to the implementation or design of IT and management systems that use the information. Understanding these characteristics would improve the chances of successfully importing new information technology and management techniques to mineral producers. The most important characteristics that should be understood are workplace issues, the industry’s dual nature of being a continuous construction project using cyclical factory processes, labour challenges, workplace culture, information availability, integrative data elements, and the current technical education of mining engineers. These characteristics were taken into account in two applications of information technology and systems design at operating companies. The research and consulting projects focused on the development of an IT-enabled performance management system at several underground metal mines in Canada and an integrated data warehouse for surface mines spread throughout the United States and Latin America.

Jan 1, 2006

By T. J. Close

The Silver Peak Range North Wilderness Study Area was deleted from the list of US Bureau of Land Management lands in Nevada to be considered for wilderness designation. This decision was based in part on the US Bureau of Mines mineral investigation of the wilderness study area which found indications of precious- and base-metal-resources. The study area lies between the Silver Peak and Dyer mining districts of west-central Nevada. The Bureau examined 13 mineralized sites, most of which were previously unknown and unclaimed. These sites are along two zones that cross the study area from the Silver Peak mining district to the Dyer mining district. The two zones transect a volcanic center of fractured and altered rocks that contain epithermal veins of quartz and calcite with gold, silver, and base-metals. At the surface, these veins are poorly defined. Exposures of the more than forty veins examined were as thick as 17 ft and as long as 1000 ft. Samples from these veins contained significant amounts of precious- and base-metals-as much as 0.02 oz per ton gold, 2.1 oz per ton silver, 1.0% copper, 2.6% lead and 0.4 % zinc. No vein large enough or of high enough grade to be classified a mineral resource was disclosed by the sample data. However, most do have indications of precious- and base-metal-resources at depth. Subsurface exploration of some of the veins is recommended.

Jan 1, 1995

By Randall Wheeler

In early 2008 we were asked by a quarry to become involved in a conflict with a pipeline company concerning blasting near one of their underground high pressure gas lines. The pipeline company, without the quarry’s knowledge, had sought and obtained a temporary restraining order against the quarry forbidding them from blasting near the pipeline.

Jan 1, 2011

By Luiza Cruz Guimarães

Os fabricantes de instrumentos endodônticos de NiTi têm desenvolvido diferentes estratégias para aumentar a resistência à fadiga e à ruptura torcional desses instrumentos. A tecnologia “Controlled Memory (CM)”, que envolve o emprego de tratamentos térmicos em instrumentos já usinados, é uma dessas novas estratégias. Neste trabalho, dois tipos de instrumentos CM foram avaliados em termos de sua capacidade de recuperação de forma e resistência à fadiga após ciclos de flexão até 45 graus e esterilização em autoclave, simulando o uso clínico. Os resultados obtidos em relação às temperaturas de transformação martensítica e reversa, ao momento de dobramento a 45 graus, à recuperação de forma e à resistência à fadiga após ciclos de flexão/esterilização mostraram que os tratamentos aplicados aos dois tipos de instrumentos, embora referenciados como tecnologia CM, produziram resultados diferentes em termos de microestrutura e propriedades.

Aug 17, 2017

By W. P. Diamond

The direct method test was developed for general mine safety applications by the U.S. Bureau of Mines in the early 1970's to measure the gas content of coal samples obtained from the relatively shallow depths of eastern U.S. coal mines. Over time, applications for gas content data evolved which required increasingly accurate desorption values. It became evident that some of the inherent weaknesses in the original direct method test could best be addressed by abandoning the water displacement based desorbed gas volume measurements. The ideal gas law based modified direct method (MDM) and associated desorbed gas volume measurement apparatus was developed to provide the most accurate desorption values possible for rock samples obtained from any gas-bearing strata. The MDM has a number of significant advantages, including: (1) increased accuracy, especially for low gas content samples, (2) a test apparatus with an integral sampling port to facilitate the collection of uncontaminated gas samples, (3) an inherent head space effect correction in the periodic MDM desorbed gas volume calculations, (4) measurement of positive and negative desorbed gas volumes, (5) elimination of differential gas solubility effects as a source of error inherent in the water displacement methods, and (6) a compact and rugged test apparatus that along with the elimination of the ?glassware? required for the water displacement methods, facilitates its use in the field.

Jan 1, 2008

By David Beck, Eko Wibowo, Hendri Silaen, Andres Sugiyanto, Karl Llewelyn

PT Freeport Indonesia’s Deep Mill Level Zone mine is one of the deepest block cave mines in the world and is in mountainous terrain in West Papua, Indonesia. The mineralization is hosted in a skarn deposit in a structural setting that is complex at the footprint, mine and regional scale. Large seismic events and significant episodes of rapid rock mass deformation are potentially critical geotechnical risks during this ramp-up stage of mining. Understanding the interaction between stress, strain, rock mass strength and geological structures is essential to minimize the hazard and engineer control measures to help ensure the safety of the employees while achieving production targets. This paper discusses how the seismicity and excavation damage have been shaped by the interactions between the mine and geological features, and how this affects strategic mining decisions. Additionally, the paper presents a summary of the mitigation measures used for mining the DMLZ in the safest and most productive way. These include improvements to geotechnical characterization of rock mass and structure, dynamic ground support designs, production scheduling for desirable cave propagation and a seismic monitoring system with re-entry protocols.

Apr 26, 2022

By M. Fornaro, E. Lovera, I. Sacerdote

"The analysis of the mining laws of the different European States reveals big diversities and, often, remarkable complications. This is due, firstly, to the history and culture of different States and, secondly, to the assets of natural resources. It is therefore difficult to find a common line between the text of the various mining laws, but it can be observed that nearly all the States distinguish the mining resources in two categories: the materials whose importance is considered strategic belong to the first category; in the second category the materials whose importance (above all economic) is mainly local are comprised. The paper, analysing in detail the planning procedures in some important Countries, investigates the possible perspectives of arranging some guide-lines for a correct approach to the sustainable exploitation planning/programming of mineral resources (with particular reference to "quarry" materials, such as aggregates), considering both the environment protection and the production needs."

Jan 1, 2005

By Ailton Lopes Junior

O projeto desenvolvido na ITM Samambaia – Itatiaiuçu – MG, de propriedade da Mineração Usiminas, teve como objetivo a implantação de um Sistema de Controle e Supervisão através do fornecimento de todo o equipamento de automação e desenvolvimento dos aplicativos de controle e supervisão. Este projeto torna possível a operação remota de toda a planta, através de uma sala de controle central, bem como, a automatização de processos como sequenciamento de partida e parada, e o monitoramento do funcionamento de todos os equipamentos da planta, além de ferramenta de acesso remoto via internet para monitoração e comando da planta, mediante política de segurança de acesso.

Jul 30, 2018

By Marcus Vinicius Dias Garcia

O presente trabalho tem por objetivo contribuir para a preservação refratária de baterias de coque, apresentando uma metodologia de planejamento e controle. A condição dos refratários de baterias de coque é crucial para sua produtividade e para o cumprimento de diretrizes ambientais. São desafios (i) a identificação precoce de danos e previsão de seu efeito no desgaste global da bateria, para hierarquia de reparos; (ii) a seleção da técnica apropriada a cada reparo. No presente trabalho, os autores compilam o estudo da progressão de danos sob diferentes tipos de reparo ao longo de mais de 30 anos em baterias heat-recovery e convencionais, de diversos modelos construtivos, e o combinam a tecnologias de inspeção para consolidar uma metodologia de gestão da preservação refratária. A metodologia foi aplicada em baterias localizadas no Brasil, avaliando a condição de mais de 400 fornos em 90 dias. Para a bateria mais crítica, foi identificado um potencial de prorrogação de vida útil em torno de 10 anos.

Aug 17, 2017

By F. H. McDowell

The increasing interest in the subject of electrical separation warrants the addition to what has already been written of a few lines covering the practical workings of the Tilly Foster mill under the direction of Mr. E. S. Moffat, General Manager. Since my last paper was presented to the Institute, Mr. S. P. Tomkins, the superintendent, has had thrust upon him for solution several problems complicated by the introduction of new conditions. 1. The richer portion of the lean ore dump, and that nearest the railroad track, having been worked up in 1890, the handling of the balance, including a largely increased amount of rock, could only be accomplished at an increased cost. 2. The tailings had accumulated close about the mill to such an extent that arrangements had to be perfected to move them further away.

Jan 1, 1893

Nuclear power currently produces about 20% of the electricity in the US, with 104 nuclear power plants located in 31 states. The commercial US nuclear industry contributes over $4 billion annually to US workers in salaries and wages. 25,000 new jobs need to be filled in the next 5 years. There are over 30 new power plants under consideration by US utilities. The operating reactors use uranium oxide fuel enriched to about 4% U235 and fission is the process used to generate heat to form steam to drive the turbine generators. Nuclear energy is an important element in the US generation portfolio and represents the largest producer of nearly emission-free electricity. Most, if not all, of the operating plants will secure an extended 20 years of operation or more. The last plant constructed was ordered in 1978. New smaller, modular reactors are under design to provide less expensive, expandable generation options.

Jan 1, 2011

By Guo Wenbing

"INTRODUCTIONThere is a great amount of coal (about 140 billions tons) left unmined under the surface structures, water bodies, railways (referred to as the “three-body”). Coal mining under “threebody” especially that under surface structures has become a major problem in the mining area. The key problem of mining under surface structures is to control overburden strata and surface movements. At present, the major surface subsidence control methods are strip pillar mining, backfilling mining method, room and pillar mining, grouting of bed separations, harmonic mining, and so on. Wongawilli mining method is a high-efficient shortwall mining method developed based on the room and pillar mining, and named after the first successful trial in Australia “Wongawilli” coal seam. The room and pillar mining equipment such as continuous miner is employed in this method. Its major advantage is flexible face layout. It can be used to mine the small wedge coal blocks and those that are difficult to be mined with retreat longwall mining method. It requires less capital investment, short lead time for production, flexible equipment operation and face move and high productivity. It has been applied in some China’s coal mines.The “Wongawilli strip coal mining technology” is a new coal mining method for mining under surface structures. It combines the strip mining longwall layout and Wongawilli high efficient mining technology. This technology can fully utilize the advantages of both the strip pillar and Wongawilli mining methods, and overcomes the disadvantages such as frequent face move, and low mining efficiency in strip pillar mining, and poor ventilation condition and poor long-term stability problems of coal pillars. In this paper, the Wongawilli strip mining method was designed for Wangtaipu mine and its feasibility was studied using numerical modeling and surface subsidence prediction.Geological and mining conditionsAt present, most of the No.15 coal seam reserves totaling 377.07 million tons in Wangtaipu mine are located under surface structures. In order to mine the coal under the surface structures, the Wongawilli strip mining method was employed. An appropriate panel was selected for trial and the surface movement monitoring lines were set up. The trial area is located in panel XV2214 (East) ( re 1). In this area, the floor elevation of coal seam is +634~646m, the surface elevation is +810~817.5m, and the average depth of coal seam is about 174m.The average panel length is 282m and average panel width is 73.5m. The seam dips 1~3° and is 1.8~2.5m thick with an average of 2.15m. The roof and floor rock characteristics are shown in Table 1."

Jan 1, 2015

By V. P. Mehrotra

The effect of dissolved ions present in plant water on the flotation of phosphate ore from central Florida was investigated. Of the three most abundant ions, namely Ca++, Mg++ and SO4--, calcium ions were the most detrimental in the flotation of phosphate with sodium oleate collector. In one feed, a 10 ppm concentration of Ca++ ions reduced the BPL recovery from 86% to 46% whereas in the other a 40 ppm concentration lowered the recovery from 90% to 52%. The effect of Na2C03, NaHC03, Zeolite and EDTA to remove ca++ ions from water and hence improve apatite flotation was also studied.

Jan 1, 1986

By L. C. IlsLey

The increasing use of Diesel engines for operating equipment on trunk-line railroads and for power-plant units has stimulated interest in the use of Diesel engines for other lines of work, among which is the possibility of substituting Diesel locomotives for trolley locomotives for mines. The possibility of developing Diesel locomotives for duty in American mines is not as remote as it might seem, particularly in view of the fact that locomotives of this type are already used in considerable numbers in European mines. A study of Diesel locomotives in Europe is contained in Report of Investigations 3320, Diesel Mine Locomotives - Development and Use in European Coal Mines, by George S. Rice and F. E. Harris.

Jan 1, 1938

By W. K. Choi

Stainless steel exposed to wet environments at ambient temperature is subject to the formation of a surface biofilm. Depending upon the prevailing environmental conditions (dissolved oxygen, pH, Eh, concentration of cationic/anionic species), the biofilm may stimulate corrosion through formation of differential aeration zones and concentration cells. Corrosion significantly impacts the United States economy, since on a yearly basis, corrosion induced losses are estimated to be over $200 billion. A large portion of this corrosion is imputable to bacterial activity, and basic information is needed for a better understanding and control of the biocorrosion phenomenon. The present study has investigated the influence of Thiobacillus ferrooxidans in the corrosion of American Iron and Steel Institute (AISI) 304, 316 and 416 stainless steel samples. The formation of biofilm and microstructural changes on the surface of stainless steel samples and their weldments were assessed by microscopic examination, and the changes in the mechanical properties by stress-strain measurements. The significance of the results will be discussed.

Jan 1, 1993

By Karim El-Ouassiti, Marc Minville, Stéphane Chabot, Claude Bazin, Valérie Ouellet

"Alumina is the main source of aluminium and it is extracted almost exclusively from bauxite ores found in the Southern hemisphere. Clays are abundant minerals that contain from 15 to 40% w/w of alumina from which it can be extracted by various processes. This paper reviews the processes used for the extraction of alumina from clays and discusses results obtained with a clay sample from the Murdochville area in the Quebec Province. The application of a conventional process to this clay did not yield an acceptable recovery although smelter grade alumina was produced. A modification to the process allows increasing alumina recovery from 85% to more than 92%. The application of the improved flow sheet to other alumina carriers failed to yield comparable recovery, showing that an optimum processing path for the recovery of alumina should be found for individual clay materials.INTRODUCTIONMost of the aluminium smelters are fed with alumina extracted from bauxite found in the Southern hemisphere. Bauxite is processed by the Bayer process that uses a caustic leach of the ore. In the middle of the century, the US Bureau of mines, motivated by the fear of an alumina delivery disruption, conducted several research projects aiming at producing alumina from non bauxitic ores. These projects led to the development of various acid leaching processes (Habashi, 1993). The sulphuric and hydrochloric acid leaching processes were brought to pilot plant evaluation (Bengtson, 1979), while nitric and other leach liquors were tested in the laboratory (Phillips and Wills, 1982; Habashi, 1983). Although clays are abundant and inexpensive minerals, the studied processes remained uncompetitive with the alumina extraction from bauxite (Hudson, 1987 page 42; Peters et al., 1962) for which reserves are estimated to support alumina production for the next 50 years (Oye et al., 1999). On the other hand, the local extraction of alumina from clays could significantly reduce the transportation costs of alumina to smelters and provide an alternative source of alumina supply from the Southern hemisphere countries. Also, the extraction of secondary products for some types of clay (Nasyrov et al., 1999) containing significant amounts of potassium and sodium could provide an additional return that may improve the economics of alumina production from clays."

Jan 1, 2005

By Edward (Ted) M. Dowey

Shaft 26B of New York City’s Third Water Tunnel was constructed by Frontier-Kemper Constructors, Inc. of Evansville, Indiana. The 176.8 m (580 ft) deep shaft will serve as the construction shaft for the Manhattan spur of Water Tunnel No. 3. Twelve m (40 ft) of over-burden was supported by a rectangular cofferdam. This shaft was excavated in 13 months, through 164.6 m (540 ft) of rock, using 24,040 kg (26.5 tons) of explosives. Concrete lining cycles included the installation of stainless steel pipes embedded in the lining as the shaft advanced. A total of 635 m (2,084 linear feet) of stainless steel pipe was installed.

Jan 1, 1997

By Johne Jesus Mol Peixoto

No reator RH, a otimização do fluxo recirculatório de aço entre a câmara de vácuo e a panela é a chave para promover as reações de refino. Neste trabalho, foram utilizados água e solução de cloreto de zinco (ZnCl2) como fluido similar ao aço para investigar a taxa de circulação no modelo a frio de um reator RH em escala 1:7,5. A taxa de circulação foi determinada utilizando o método de pontes de Strain Gages. A técnica PIV foi utilizada de modo a calibrar e validar os resultados. O aumento da vazão de gás de 30l/min para 120l/min resultou na elevação da taxa de circulação para ambos os fluidos. Cálculos preliminares demonstraram que há grande diferença nas condições de arraste de escória entre os sistemas água/óleo e ZnCl2/óleo.

Aug 17, 2017

By William Pitman

Ground instability and subsequent rock falls are a major concern in underground mines. As a result, several mining companies are conducting risk assessments of the ground support installed in their mines. Risk assessment is now commonly used to provide mine operators with a systematic process to assess the strategic risks that could lead to injury to personnel or loss of production, and evaluate possible risk control measures. Risk assessments can be carried out to identify major hazards, assess the likelihood of occurrence and consequences of each hazard and estimate the level of risk. This process allows assessment of possible remediation actions to minimize the risk and likelihood of occurrence or mitigation of the consequences to a level that is reasonable and practical. This paper presents two practical mine applications of qualitative risk assessment of ground support to highlight the benefits of this process. Yearly or bi-yearly risk assessment of mine excavations can assist mine operators in prioritizing resources and areas that require support remediation. In addition, it provides a mechanism for proactive response to reduce potential risks associated with personnel safety, equipment safety and environmental impact. It also provides a baseline against which changes in ground condition can be compared and quantified.

May 1, 2004