Search Documents

By H. M. Thorne

The oil-shale deposits of the Puertollano basin in the Spanish province of Ciudad Real appear to have been give little consideration in discussions of oil-shale resources throughout the world. A small, integrated oil-shale operation has been conducted at Puertollano since about 1922 by a French company, Sociedad Mimora y Metalurgica de Penarroya, hereinafter referred to as "Penarroya", but only within recent years have the potentialities of the Spanish oil-shale deposits been recognized. Empresa Nacional "Calvo Sotelo" do Combustibles y Lubricantes, hereinafter designated as "Calvo Sotelo," which was created in 1942 by the National Industrial Institute of Spain to produce liquid fuels from oil shales, has made marked progress in the design and construction of a complete oil-shale plant at Puertollano. Penarroya is mainly a coal-mining company, and the oil-shale operations were on a small scale of approximately 220 tons a day in October 1947. It is an integrated operation comprising oil-shale mining and retorting and shale-oil refining. Motor gasoline, Diesel fuel oil, light burner fuel oil, lubricants, paraffin wax, cresols, and ammonium sulfate are manufactured.

Jan 1, 1950

By Peter Zhang, Todd Minoski, Gabriel Esterhuizen, Jack Trackemas, Berk Tulu, Morgan Sears

Roof stability in the belt entry is critical for safe and continuous production of coal during longwall mining. Previous studies of roof falls that occurred in belt entries have shown that the roof falls were largely associated with high in situ and longwall-induced horizontal stresses [1,2,3,4]. To properly support the roof in a belt entry, it is important to understand how longwall-induced horizontal stress changes can affect roof stability in the belt entry. Monitoring of horizontal stress changes was conducted in the belt entries of two Pittsburgh seam longwall panels oriented unfavorably to the major horizontal stress. Numerical models were also set up to investigate how horizontal stress concentrates and relieves in the belt-entry roof near the face as panel orientation changes. Both measurements and modeling results show that high horizontal stress concentrates in the belt entry roof within about 15 m outby the face. The study demonstrates that longwall-induced differential horizontal stress can be used to evaluate the horizontal stress concentration factors. The horizontal stress concentration factors change with panel orientation, resulting in high stress concentrations at orientations between 20 and 110° and low stress concentrations between 130 and 180°. Roof support strategies are given for the belt entries under the influence of high horizontal stress. For unfavorably oriented panels in weak roof conditions, supplementary support should be installed during development, and cable bolts should be anchored into a stable roof horizon. The bolting pattern should be designed to cover both entry corners and the entry center to prevent potential roof cutters and sagging.

Jan 1, 2023

By Leticia Costa Macêdo

Esse trabalho tem como objetivo analisar por meio da termodinâmica computacional a influência do K2O na dissolução das fases sólidas formadas durante o processo de dessulfuração de ferro gusa. Para isso, foi utilizada a cal como agente dessulfurante e a Sodalita (Fonólio) como fundente, realizando uma adição de K2O no fluxante de 1% a 10%, com uma temperatura de trabalho de 1400ºC. Por meio do uso de software de termodinâmica computacional FactSage, foi possível simular e avaliar as fases sólidas e líquidas formadas na temperatura determinada e comparar com os resultados obtidos com outras análises. Os resultados obtidos mostraram que o aumento gradativo de K2O levam a um aumento do potencial termodinâmico de dessulfuração e melhores condições cinéticas, sendo a mistura que apresentou os melhores resultados a que continha 10% de sodalita com adição de 10% de K2O na fonte.

Oct 30, 2017

By T. M. “Mike” Gurr

"U. S. marketable phosphate rock production for the 2018 crop year (July 1, 2017 to June 30, 2018) showed an increase to 27.7 Mt (30.5 million st) from the 2017 crop year production of 27.1 Mt (29.8 million st), as reported to the U. S. Department of the Interior by the mining companies operating in the United States during crop year 2018 (Table 1). Domestic consumption decreased in the 2018 crop year to 23.9 Mt (26.3 million st), as compared to the 27.2 Mt (30 million st) consumed in crop year 2017. U.S. imports of phosphate rock increased to 3 Mt (3.3 million st) for the 2018 crop year from the 1.81 Mt (1.9 million st) for crop year 2017. Imports of phosphate rock were from Peru and Morocco. There was an increase of 2.85 Mt (3.1 million st) in producers’ stocks from 7.45 Mt (8.2 million st) in crop year 2017 to 10.3 Mt (11.3 million st) in crop year 2018 (Table I).For calendar year 2018, Florida and North Carolina phosphate rock production accounted for 75 percent of the total U.S. production, with the balance being produced in Idaho and Utah. The Florida and North Carolina percent of U.S. production is declining. U.S. production of 25.7 Mt (28.3 million st) in calendar year 2018 was produced by five companies at 10 mines in four states and accounted for approximately 9.6 percent of the world production of 267.7 Mt (295 million st) for calendar year 2018 (Table 2).In calendar year 2018, U.S. phosphate production decreased by 2.2 Mt (2.4 million st), while companies increased stocks of phosphate rock by 1.7 Mt (1.9 million st). The domestic production for calendar year 2018 of 25.7 Mt (28.3 million st) represents 78.4 percent of the domestic production capacity of 32.8 Mt (36.1 million st).At present, China reportedly produces more than 50 percent of the world’s phosphate rock. As a result of planned expansions, Morocco production has increased from 27 Mt (30 million st) in 2017 to 33 Mt/a (36 million stpy), which is approximately 12.3 percent of the world’s production, moving ahead of the U.S. production. In calendar year 2018, the U.S. phosphate rock production was 25.7 Mt (28.3 million st), which is less than 10 percent of the world’s production of phosphate rock (Fig. 1)."

Aug 1, 2019

In 1987 the control strategies at the then ZC Mines' New Broken Hill Consolidated concentrator were a miscellaneous mixture of computer hardware and technology for ISA, grinding and residue thickener control. Field instrumentation was based on current-to-air technology of approximately the 1960s. Decisions were made to rationalise computer and field instrumentation technologies; the object being to consolidate control loops into one system to enable expansion of the system to include all facets of plant operation. The first stage was to install a DEC Micro PDP 11/23 computer and serial line communication as recommended by AMDEL Ltd, for the ISA system, as discussed by Walsh and Freeman (1988). The second stage was to select and install a distributed control system for the centralisation of the control loops into one system, and to replace field instrumentation with state-of-the-art technology. This paper deals with the second stage of the rationalisation, in an attempt to give an insight into what is required when personnel are faced with such a decision, details of costs involved in keeping a system functioning and utilised; and the requirement to train personnel for acceptance of further control strategies.

Jan 1, 1991

By Joelma Krugel Brites

Com a perspectiva do uso de aços API em ambientes sour service, o controle de inclusões e precipitados é essencial para bom desempenho. A precipitação de carbonetos e nitretos de Nb e Ti, assim como a formação do MnS foram analisados criticamente em aços de alta resistência e baixa liga – HSLA- com Mn entre 0,3 e 1,6%, Nb 0,02-0,1%, S 0,001-0,005% e Ti 0-0,02% em peso. Os valores da temperatura de precipitação do MnS, Nb(C,N) e Ti(C,N) foram obtidos por meio do software ThermoCalc™. A partir desses resultados, possíveis tendências da precipitação foram discutidas e relacionadas com a temperatura de não-recristalização, traçando um comparativo entre temperaturas de processo e precipitação. Três aços produzidos com a composição estudada atenderam os requisitos mecânicos de tração da norma API 5L X65M.

Oct 30, 2017

By A Woodley, A N. Danoucaras

In 2012 the Bureau of Meteorology, under the banner of the Water Accounting Standards Board, released the Australian Water Accounting Standard 1 (AWAS 1). This standard has been in development since 2007 with key milestones being the release of the Preliminary Australian Water Accounting Standard in 2009 and the exposure draft of the Australian Water Accounting Standard in 2010. Throughout this period, the Minerals Council of AustraliaÆs Water Accounting Framework has developed concurrently with the Australian standards and the standards have informed elements of the framework. However, the framework is not identical to the standard as the objectives between the two are different. The objective of the Water Accounting Framework is to create consistency in water reporting of the minerals industry and to assist companies reporting to corporate sustainability initiatives. The objective of AWAS 1 is to provide information to water management bodies to facilitate decisions about the allocation of water resources. Companies are to report on an annual basis - not only physical flows of water but contractual requirements to supply and obtain water - regardless of whether the transaction has been fulfilled in the reporting period. In contrast, the Water Accounting Framework only reports on flows that have physically happened. The paper will provide summary information on aspects of AWAS 1 that are most relevant to the minerals industry, show the alignment and differences between AWAS 1 and the Water Accounting Framework and explain how to obtain the information for the AWAS 1 reporting statements.CITATION:Danoucaras, A N and Woodley, A, 2013. Alignment and differences between the Australian Water Accounting Standard and the Water Accounting Framework for the minerals industry, in Proceedings Water in Mining 2013 , pp 85-90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By Márcio Zamboti Fortes

A alguns anos os setores residencial e industrial tem se deparado com mudanças de paradigmas que tangem a necessidade de melhorias em suas atividades, com o intuito de desenvolver processos com menor impacto ambiental, sustentáveis e com eficiência energética, objetivando reduzir o consumo de energia elétrica. O uso de tecnologias baseadas em fontes renováveis para a geração de energia elétrica, tais como a solar e a eólica, tem apresentado-se como uma alternativa a ser implementada por estes setores para atender às exigências do mercado, se beneficiando da difusão da tecnologia e uso destes equipamentos, para a consciente utilização da energia elétrica. A instalação e avaliação de novas fontes de geração de eletricidade estão sendo desenvolvidas pelo projeto Cidade Inteligente de Búzios através da implantação de painéis fotovoltaicos e aerogeradores de pequeno porte em unidades consumidoras residenciais, comerciais e industriais e alguns resultados estão apresentados neste texto.

Sep 25, 2017

By Rafael Abreu Fraga

Foram avaliados os efeitos da tecnologia de laminação seguida da têmpera direta na produção de chapas grossas de alta dureza, resistentes à abrasão, na Linha de Chapas Grossas da Gerdau Ouro Branco. Para tanto, foram analisados os parâmetros de processo e propriedades mecânicas, através da realização de ensaios de dureza, tração, tenacidade ao impacto Charpy e metalografia. A tecnologia de têmpera direta, realizada através do Mulpic, possibilita a fabricação de aços de alta dureza com carbono equivalente significativamente baixo. O mecanismo principal para aumento da dureza, baseia-se em uma laminação com passes de alta redução, iniciando o resfriamento com o aço ainda constituído exclusivamente pela fase austenítica, sendo temperado a baixas temperaturas, ocorrendo a completa transformação martensítica. Tanto o processo de têmpera direta no Mulpic, quanto os processos anteriores precisam ser muito bem controlados, visando uma microestrutura homogênea e um produto com a planicidade adequada.

Oct 30, 2017

By Samara Venina Simen de Azeredo Silva

Os compósitos produzidos a partir de Nitreto cúbico de Boro (cBN) são utilizados nos processos de usinagem de materiais ferrosos, tais como, peças fabricadas a partir de ligas ferrosas, ligas a base de níquel e materiais ferrosos com dureza de 45 HRc. Os compósitos a base de cBN são produzidos sinterizando cBN e seus ligantes sob condições de altas pressões e altas temperaturas (APAT). O presente trabalho tem como objetivo a caracterização microestrutural dos compósitos nanoestruturados de cBN, processados sob altas pressões e altas temperaturas, com parâmetros de pressão de 6,6 GPa e 1800oC e tempo de processamento cíclico e acíclico. Os compósitos produzidos foram testados na usinagem de aço 4140. Os resultados mostraram que uma melhor densificação e uma menor perda de massa dos compósitos durante a usinagem tem relação com os parâmetros de sinterização e com o tempo de processamento.

Aug 16, 2017

By R. L. Levens

The Underground Injection Control program was promulgated in 1981 by the U.S. Environmental Protection Agency under the provisions of the Safe Drinking Water Act. Placement of mine waste backfill underground is considered underground injection under the provisions of this program. A major issue is whether mine waste that is regulated as a contaminant source on the surface should be disposed of underground. The U.S. Bureau of Mines conducted research to investigate the impacts of mine waste sandfill on the quality of ground water. Analyses of water samples collected before and after contact with sandfill in a 10-year-old stope, as well as samples of the sandfill itself, were used to ascertain the influence of the sandfill after mine closure and subsequent flooding. Computer models supported the hypothesis that oxidation of pyrite by oxygen, accompanied by dissolution of carbonates, was the predominant reaction controlling the quality of the water being discharged from the stope. Concentrations of metals released as a result of acid production remained near or below detection limits. Metals release after mine flooding is expected to remain low as a result of the buffering by the sandfill and the reduced rate of oxidation.

Jan 1, 2010

By Zhuokun Cao

Manufacture of aluminum foams still suffer from nonuniformity and poor reproductively for there is lack of basic knowledge of foaming process. In this paper, carbon fibers are used as novel stabilizing additive for aluminum foams, and the structure evolution of aluminum foams with different fiber content was studied. A laser rangefinder was used to detect the expansion rate of different al foams. Al foam samples are solidified at different foaming time to determine its relative density and cell size distribution. Results indicate that the cell size of foams linearly increases with the decrease of density, and the slope of the line is influenced by fiber content. The relationship between expansion ratio, density and cell size of the foams is discussed. It is concluded that the density of resulting foam is influenced by the rate of gravity driven drainage, and its cell size is determined by expansion ratio and foaming time.

Jan 1, 2010

By Hamid Maleki

A geotechnical monitoring program has been implemented at Energy West Mining Company for enhancing site-specific evaluation of longwall stress conditions. This program consists of underground measurements at five locations in two neighboring mining districts located in the Hiawatha and Blind Canyon Coal Seams under moderate to deep cover. Within the last five years, additional measurements, including data on recorded seismic events and face conditions, have been incorporated into the data collection program together with detailed geologic mapping of longwall gateroads. In conjunction with the measurement program, the authors have completed detailed boundary-element stress analyses of the mine plans. Models have been calibrated using the data from in-mine instrumentations and then routinely used for evaluation of mine plans at depths approaching 2,600-ft. The work has improved our understanding of load transfer, seismicity and yield pillar performance. It has identified areas of potential increased stress levels at certain longwall face positions and provided guidance to measures that could be considered to mitigate the potential for these increased stress levels.

Jan 1, 2009

By G Hill, D Grant, M Tyler

Located approximately 570km NNW of Adelaide in South Australia, the Olympic Dam mine (OD) is the world’s fourth largest remaining copper and gold resource and the largest uranium resource. Discovered in 1975 and going into production in 1988, the operation consists of a fully vertically integrated underground mine, mineral processing plant, copper smelter and refinery, as well as associated infrastructure. BHP achieved production of 203,000 tonnes of copper cathode plus associated by-products in financial year 2016. The immense size and high-grades of the Olympic Dam resource offer a range of growth pathways, making closure timing estimation and planning a challenge. Current estimates put the OD resource at approximately 79 million tonnes of copper. Major factors influencing the closure timing estimation, as a result of the large resource and grade tonnage profile, include the mining method that may be used and the downstream processing method, ultimately influencing such things as the total disturbance area and the extent of infrastructure to be demolished at the end of mine life. In addition, factors such as the mining and processing method and production rate have a direct impact on larger rehabilitation items such as the total number of tailings cells required.CITATION:Grant, D, Tyler, M and Hill, G, 2018. Olympic Dam mine closure planning process, in Proceedings Life-of-Mine 2018, pp 43–45 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By Juh W. Chen

A process for recovery of energy from waste coal fines was investigated. The process, which was developed through laboratory, bench, and pilot plant scale experiments, consists of mechanical cleaning followed by high temperature oil agglomeration and pelletization. The process can produce a quality product under an economically and environmentally acceptable condition. Waste coal fines with ash less than 35: and HHV greater than 6,000 BTU/1b have been upgraded to a product with less than 15% ash and HHV Greater than 11,500 BTU/lb. A computer model has been developed to optimize the processing costs and to perform economic evaluation of specific sites. Ultimately tine model can be utilized to establish a priority listing for a region in assisting the determination of reclamation strategy.

Jan 1, 1983

By Dean H. Ambrose

[Mining and processing earth's materials form the basic building blocks from which many technology advancements and products are made. Virtually all metallic and non- metallic products are derived from a substance found in our earth that we blend, mold, extrude, or pulverize into something useful, the mining industry is responsible for the first step of this process: extraction from the ground. Mining particularly coal mining. poses significant risks to both humans and machines. As raw materials are]

Jan 1, 2009

By Magno Luiz Tavares Bessa

Visando melhorar a distribuição de micropartículas de diamante (MD) na formulação de compósitos, foi desenvolvida, através da emulsão do sistema epóxi/poliamida em água, uma técnica de encapsulamento de MD. As MD foram pré-recobertas com um polímero baseado no sistema epóxi-poliamida e posteriormente utilizadas como carga na produção de um compósito com matriz da mesma composição do revestimento. A matriz epóxi/poliamida e compósitos com carga de MD encapsulados e sem recobrimento foram avaliados. As propriedades mecânicas foram avaliadas por ensaio de flexão em 3 pontos e por análise de tenacidade à fratura e as propriedades térmicas por DMA. Por MEV foram observadas a microestrutura das MD encapsulados e a superfície de fratura dos corpos de prova após ensaio de flexão. Não foram observados aumentos nas propriedades mecânicas do compósito com carga MD encapsulados em relação ao compósito com carga de MD não modificados. Esse resultado foi devido à adição ao sistema de defeitos estruturais como bolhas e ar e porosidade provenientes do uso das MD encapsulados. Foi observado porém, melhor distribuição das MD no sistema e uma melhor adesão à matriz para a carga de MD encapsulados em relação à carga de MD não revestidos, em função dos resultados obtidos por DMA.

Oct 30, 2017

By Thales Renó Grilo

O presente trabalho teve como objetivo analisar as diferentes microestruturas do aço inoxidável duplex UNS S32304 obtidas pelo processo de soldagem Gas Metal Arc Welding (GMAW). As regiões do metal base, zona fundida e zona afetada pelo calor foram investigadas nos corpos de prova com diferentes aportes térmicos. As microestruturas obtidas foram caracterizadas utilizando-se a microscopia óptica (MO). As imagens de Mo obtidas na zona afetada pelo calor mostram que a fração de austenita aumentou com o aumento do aporte térmico. Este aumento está relacionado ao alto teor de cromo e molibdênio presentes no metal de adição utilizado na soldagem. Na zona fundida, a fração de austenita de widmansttaten foi observada com maior frequência na microestrutura do corpo de prova soldado com o aporte térmico de 1,87KJ/mm. Essa maior fração de austenita de widmansttaten observada para o aporte térmico de 1,87KJ/mm está relacionada com o maior tempo de permanência em altas temperaturas deste corpo de prova em relação aos outros corpos de prova investigados. Vale ressaltar que a adição de nitrogênio também promove a formação desta fase. De modo geral, os resultados da metalografia quantitativa mostram que a porcentagem de ferrita foi superior a 65% nas zonas termicamente afetadas e fundidas.

Aug 17, 2017

By Cyro Takano

A tecnologia de autorredução apresenta um grande potencial por apresentar características de alta velocidade de redução e de eficiência energética, resultando em economia de energia e em alta produtividade na produção de metal primário. Têmse dois processos consolidados de aglomeração. A utilização de cimento como aglomerante, com cura a frio que formam hidratos que conferem resistência, apresenta problema principal de sofrer degradação às temperaturas na faixa de 800 a 1000 °C, devido à decomposição dos hidratos. O outro processo é o de utilização das propriedades do carvão de alta fluidez e tratá-lo termicamente para que sirva de redutor e aglomerante. Este processo não é o de cura a frio, porém diminui consideravelmente a quantidade de escória em comparação com a utilização de cimento. O objetivo deste trabalho é o de analisar, na literatura técnica, os aglomerantes alternativos e iniciar os ensaios para verificar os comportamentos de resistência mecânica, principalmente a quente. Em função dos resultados a etapa seguinte será a de projetar um processo que seja compatível com resistência mecânica a quente. A análise resultou em sugestões para os ensaios. Os resultados preliminares, com utilização de bentonita e ácido bórico estão indicando resistência a quente das pelotas melhores que as obtidas com a utilização de cimento.

Aug 17, 2017

By Ana Maria Gontijo Figueiredo

Muitos dispositivos biomecânicos têm sido produzidos com ligas superelásticas (SE) de NiTi. Na maioria das aplicações, o material é submetido a solicitações mecânicas cíclicas, tornando seu comportamento sob fadiga um parâmetro importante. Neste trabalho são apresentados resultados de ensaios de fadiga por flexão rotativa de um fio SE, ensaiado a seis temperaturas diferentes, sob amplitudes de deformação (?a) variando de 1% a 12%. As curvas mostram que a vida em fadiga do material na fase martensítica estável (ME) é cerca de 100x maior do que na fase austenítica estável (AE). A curva do fio SE se aproxima da curva do fio AE para pequenas ?a e, com o seu aumento, se aproxima da curva do fio ME quando ?a aumenta. As superfícies de fratura obtidas foram observadas ao microscópio eletrônico de varredura e foram calculadas as áreas correspondentes à fratura por fadiga (af). Os resultados mostram que, para o fio nas fases AE e ME, af decresce continuamente com o aumento da ?a. Para o caso do fio SE, af permanece relativamente constante para valores intermediários de amplitude de deformação (2% a 8%). Para uma mesma deformação, af cresce com a redução da temperatura, com o consequente aumento do número de ciclos para falha.

Aug 8, 2018