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By Luiz Fernando Pimentel Simões

Neste trabalho são apresentados o planejamento e preparação para o início da operação, o período de “ramp up” e estabilização da produção da sinterização da Companhia Siderúrgica do Pecém. Incluindo a estruturação e execução do comissionamento; elaboração dos procedimentos para operação aliado a implantação do sistema de gestão da qualidade; definição do quadro de pessoal, seleção, contratação e treinamento; definição das especificações de matérias-primas, aquisição dos primeiros lotes, com desenvolvimento de fornecedores locais; apresentação dos resultados dos principais indicadores de produção e qualidade no período de “ramp up” e estabilização da planta.

Oct 30, 2017

By T. S. Qiu

In view of the bad effect that Na-bentonite direct adsorb Pb2+-containing wastewater, this article has carried out two kinds modification treatment on Na-bentonite: the direct microwave radiation modification and microwave radiation organic modification by adding quaternary ammonium salt?cetyltrimethylammonium bromide,and analysis the main influencing factors of the modification effect. In static conditions, preparing Pb2+-containing wastewater as the research object, it has respectively studied the effects of Na-bentonite, microwave soil of direct microwave modification and microwave soil of organic modification on the process of adsorption Pb2+, and discusses the effects of pH value, temperature, adsorbent dosage, stirring time on the adsorption Pb2+ in wastewater by modified bentonite, at the same time it does a verification test to the practical Pb2+-containing wastewater. Comparison the effects of adsorption Pb2+ in wastewater, the results show that organic modified microwave bentonite is obviously better than direct microwave modified bentonite and Na-bentonite, and can make 6 mg/L Pb2+-containing wastewater meet the national discharge standards. Through scanning electron microscope, the result of test is that organic modified microwave bentonite is the cause of improving adsorption Pb2+ in wastewater. Preparing modified bentonite by microwave heating will not only shorten the response time, reduce energy consumption and work-load, but also modified effect is good.

Jan 1, 2014

By D. Tao

Coal is a major source of energy in the U.S. and more than 51% of the electricity used in the country is generated from coal. Coal cleaning prior to combustion is necessary and often accomplished using wet physical processes at coal preparation plants to remove impurities such as ash, sulfur, mercury. However, the resultant clean coal product still contains a significant amount of impurity due to the fact that impurities are not well liberated from coal particles ranging from several millimeters to inches in size at which wet cleaning processes take place. A cleaner coal product can be obtained if a cost-effective dry process is developed to further clean pulverized and thus better liberated fine coal at the power plants prior to its combustion. The benefit of such a process is a significant reduction in the cost of expensive post-combustion chemical cleaning processes such as flue gas scrubbing employed to meet the stringent environmental air quality regulations. In this study, a novel rotary triboelectrostatic separator (RTS) was investigated for its application to dry cleaning of fine coal samples acquired from the power plants in the state of Illinois. The pulverized fine coal contains well liberated ash and pyrite minerals and is an ideal feed to the triboelectrostatic separator for further cleaning without the use of water or any chemical reagents. The proprietary rotary triboelectrostatic separator (RTS) is characterized by an innovative high efficiency rotary charger, charger electrification, laminar air flow, and specially designed electrodes. Compared to existing triboelectrostatic separators, the rotary triboelectrostatic separator offers significant advantages in particle charging efficiency, solids throughput, separation efficiency, applicable particle size range, etc. Testing with several fine coal samples has demonstrated that this technology can significantly reduce ash content with a process efficiency similar to or better than froth flotation. Important process parameters such as charger rotation speed, injection and co-flow rate, feed rate were investigated for their effects on separation performance.

Jan 1, 2010

By Maybee Vásquez, Robert Santos, Marco Jáuregui

El presente trabajo técnico nace de la necesidad que tenía Minera Yanacocha de ubicar los sectores más importantes para la realización de sondajes diamantinos, los cuales ayudarían a la confirmación o adición de nuevos recursos para el proyecto Chaquicocha Subterráneo, así como para establecer la línea base para operar la futura mina. Así, se analizan tanto los riesgos identificados como los controles a tener en cuenta durante el desarrollo de excavaciones mineras subterráneas en ambientes con alto contenido de azufre nativo y se confirma que es posible desarrollar excavaciones seguras en estos ambientes, a la vez que se establecen lineamientos generales para el desarrollo de este tipo de proyectos.

Sep 20, 2019

By B. Tougas

Recycling of titanium represents an important economic activity due to high cost of the material and the amount of returns of machined parts which represent the bulk of finished titanium products (typical "buy to fly" of 10 in the aeronautic industry). In the present work, the metallurgical quality of 76 mm in diameter and 20 cm ingots poured in coated graphite mold will be assessed against the nature and condition of application of 4 coatings namely aluminum oxide, yttrium oxide, zirconium oxide and zirconium oxide with 4% aluminum oxide. The metallurgical quality has been evaluated in terms of alpha case thickness, microstructure and composition. Microhardness from surface will be assessed against casting conditions. Least square regression analysis have been use to optimize casting conditions.

Jan 1, 2011

By Yan Lap J. Kan

"A waterfront stabilization system consisting of Deep Soil Mixing (DSM) columns, vinyl sheet pile fascia, and concrete flood walls supported on shallow footings was designed and constructed for a high-density waterfront development in Northern California. The project site is underlain by soft, compressible organic soil locally known as Bay Mud that has been capped with loose sand and imported fill. The waterfront stabilization system constructed at the site mitigates liquefaction, consolidation settlement and seismic potential slope deformation along the waterfront; the system was designed to reduce lateral displacements to tolerable amounts for the proposed structures. This paper presents the general design methodologies, construction challenges and quality control of this waterfront stabilization system.INTRODUCTIONUrban development in Northern California is fueling innovations in geotechnical engineering as more complex sites are developed. ENGEO Incorporated introduced a deep soil mixing technology from Japan to the US and designed a waterfront stabilization system for a high density waterfront development project in Redwood City, California. The approximately 12½-acre project site, as shown on Fig. 1, is surrounded by water on three sides, with an inner marina at the center of the site.The project site is located in the seismically active San Francisco Bay Area in California. The San Andreas Fault, the Monte Vista-Shannon Fault, the Hayward Fault and the San Gregorio Fault are major active faults located within 25 miles of the site. Once a former marshland with a major slough until the late 1950s, the site was reclaimed by placing imported fill over the native compressible clay deposits, locally known as Bay Mud."

Jan 1, 2016

By J Jeffrey, G W. Wilson, L Gilbert, C

Prior to the commencement of mining, the acid rock drainage (ARD) potential of the waste rock to be produced by an open cut mining operation is assessed by a variety of techniques carried out on drill-hole samples. These include, among others, acid base accounting (ABA), net acid generation (NAG) testing, and kinetic testing. Based on the results obtained, a strategy for the identification, separation and selective placement of waste rock having different potentials to form ARD is developed. During the course of mining, the waste rock classification scheme will be re-assessed periodically to confirm that it is appropriate. This re-evaluation may result in a change in classification scheme, and waste rock dump samples may be obtained for ARD assay purposes to confirm the appropriateness of the revised scheme. The paper describes the evolution over time of the scheme used to classify waste rock at a major open pit gold operation in New South Wales, Australia, including the development of a hydrological model. To confirm the appropriateness of the revised scheme, ARD assay testing was carried out on drill-hole samples collected from dumps having different ARD potential designations, including Non-Acid Forming (NAF), Potentially Acid Forming (PAF), and Low Grade Ore stockpiles. The results of the ARD assay testing and water quality monitoring confirmed the appropriateness of the ARD potential designations and the revised classification scheme, which has been adopted.

Jan 1, 2003

By P R. Lock

The Silver Swan nickel mine is located at the Black Swan Nickel Project, 53 km north east of Kalgoorlie, Western Australia. The Silver Swan orebody is a massive sulphide nickel deposit dipping 70¦ east with an average in situ grade of 14 per cent. Mining of the massive orebody is by Mechanised Ramp Cut and Fill (MRCF). A mining recovery of 98 per cent and minimising dilution are primary goals in extracting the high-grade ore. Placing a distinguishable marker bed (working platform) on rock fill was identified as a key method to achieving these goals. Gravel from a pit located onsite was considered the most suitable material for the marker beds. Research undertaken to design the marker beds using the gravel revealed conventional methods used in mining would not suffice, but that road stabilisation methods could be a viable alternative. Trials used a road recycler to mix cement and gravel in situ and several test beds were constructed on the surface to determine the final design. The trials attempted to replicate a marker bedÆs life cycle of construction and placement and mucking of ore from the marker bed. Testing the marker bed for strength for use as a working platform was completed using a Clegg Hammer; good correlation to a Clegg Impact Value and the compressive strength of the stabilised gravel was found. This paper describes the use of a road stabilisation machine, tests conducted, monitoring and marker bed design and discusses underground placement of the marker bed and its performance.

Jan 1, 1998

By Helder Keitaro Arçari Ambo

Aços IF (Interstitial Free) são materiais com grande capacidade de serem conformados a frio, normalmente na forma de chapas, utilizados na indústria automobilística na fabricação de carrocerias de automóveis e outros componentes similares. Neste artigo foi realizado ensaio isotérmico de dupla deformação com objetivo de determinar a fração de amaciamento que ocorre no intervalo entre passes e o parâmetro de amaciamento4. O método para obter estes dados foi utilizando software da Instron em conjunto a maquina de torção e o forno de indução. Os resultados obtidos foram de grande importância no estudo para avaliar o comportamento do material quanto aos fenômenos metalúrgicos e termomecânicos envolvidos, ou seja, se ocorre recuperação, recristalização dinâmica entre outros processos de restauração do material quando submetido a forças externas em elevadas temperaturas.

Oct 30, 2017

By C J. Moran

The Gladstone region, as one of the most industrially intense regions in Australia, uses significant quantities of fresh water. Awoonga Dam, situated on the Boyne River, is the only major source of water in the region. The current typical annual usage is 53 GL (Porteous, 2006) and approximately 80 per cent of the water is used by heavy industry (Gladstone Area Water Board, 2004). Until relatively recently, there has been ready and easy access to raw water for industrial use. The recent drought, which resulted in severe water restrictions in 2002 and 2003, emphasised the importance of water for a dominant industrial region like Gladstone. Although now in the process of changing, the typical contractual arrangements in the past have provided little financial incentive for efficient water use. From research undertaken on potential water reuse opportunities, several key questions have emerged related to water management in an industrial region such as Gladstone. This paper highlights these key questions, presents findings from recent regional strategies and assesses the potential for water reuse. Even though there is no clear-cut financial incentive for reusing water, there could be stronger regional and risk mitigation drivers for doing so. Initiatives to incorporate adaptive capacity through collaborative industrial synergies would allow for robustness and resilience in water security, leading to long-term sustainable water management across the Gladstone region.

Jan 1, 2006

By Rossano Augusto Pilon Nunes

A pelotização é um dos processos desenvolvidos para permitir utilização dos finos (pellet feed) nos reatores de redução. O produto gerado denominado ‘pelota’ possui alto valor agregado e características físicas e metalúrgicas próprias. Dentro das características físicas temos as trincas que são defeitos internos e/ou superficiais que prejudicam o desempenho das pelotas nesses reatores. O estudo visou investigar as variáveis que mais contribuem para geração das trincas e em que etapa do processo a geração é mais significativa. A investigação avaliou duas usinas de pelotização de Tubarão, na geração de trincas e comparou as principais variáveis de processo segundo a literatura. Esta avaliação se deu em escala piloto utilizando um forno tipo pot-grate e mostrou forte influência das etapas de secagem descendente e pré-queima. O trabalho foi de suma importância para uma atuação mais direcionada em um futuro teste industrial.

Oct 30, 2017

By Luciana Vilarinho Ramos de Carvalho

O objetivo deste estudo foi desenvolver um modelo matemático capaz de prever as propriedades mecânicas de uma barra redonda laminada a quente em aço ao carbono, em termos de limite de escoamento e limite de resistência, considerando equações consagradas na literatura e dados industriais de processo. Foram utilizados os parâmetros de processo da laminação, tais como temperatura, deformação, taxa de deformação e tempo entre passes, e a composição química do aço SAE 1020. Os resultados calculados pelo modelo apresentaram boa concordância com os resultados medidos nas amostras, com diferença percentual de 3,34% para limite de escoamento e 2,14% para limite de resistência, além de mostrar-se adequado para previsão da evolução microestrutural, considerando as equações de recristalização estática e dinâmica. A utilização deste modelo pode levar à redução de custos com ensaios de tração e atender à demanda crescente dos clientes por estas informações nos certificados de qualidade.

Oct 30, 2017

During the first five years of operation, the Lihir gold mine has steadily increased plant throughput rate to over 4 Mtpa, well above the original design capacity of 2.8 Mtpa. Understanding how future variations in ore type impact on plant performance has been an integral part of LihirÆs development program. This paper discusses the key drivers for significant improvements to the plant, including a second oxygen plant, a pilot flotation plant, an autoclave heat recovery circuit, a pebble crushing circuit and additional autoclave feed pumping capacity. The result is a process plant with the flexibility to accommodate variations in ore type without significant loss of throughput.

Jan 1, 2003

By Miguel Lahr da Silva

Este estudo foca na análise do comportamento do módulo para cálculo da viscosidade de escórias fundidas do software FactSage 6.4. Foram utilizados dados da literatura e calculada a viscosidade de 972 escórias, no sistema CaO-SiO2-Al2O3-MgO, variando composição dentro da faixa de 2-58% de CaO, 7,4-70% de SiO2, 0-40% de Al2O3 e 0-38% de MgO, e temperatura na faixa de 1050-1750ºC. Foi encontrada uma tendência do software de produzir resultados com valores de viscosidades menores que os encontrados na literatura. O desvio médio entre os valores da literatura e calculados foi de 32,06%, segundo estudos da literatura é considerado adequado para viscosidades de escórias siderúrgicas fundidas.

Aug 16, 2017

By M English, M Yumlu

At times of high metal prices, mining projects that have previously been put into the ætoo hard basketÆ are now being more closely examined. Typically these projects include the potential recovery of small mineable tonnes with high contained metal values and often with poor ground conditions. For many underground mining projects, the drift and fill method is viewed as a high-cost method and a æmethod of last resortÆ. As a result the method is not well known in Australia and it is the authorsÆ view that the method is under utilised. The drift and fill method can be applied to a variety of underground mining situations and is a preferred method for some orebody geometries and where ore recovery is viewed as a key to project success. This paper examines some of the critical mine planning and backfill issues involved with the drift and fill mining method.

Jan 1, 2008

By M Chiquito, R Castedo, P Segarra, L M. López, J A. Sanchidrián, J Navarro

The aim of this work is to assess the performance of different constructive solutions against explosions on the strength of masonry walls. The solutions tested, namely an external metal mesh, a glass fibre film on the external face of the wall and a basalt fibre film located on the inner face of the wall, have low to medium cost and are originally designed for other purposes, like seismic protection. Four cubic boxes 3 × 3 × 3 m were built using each of the solutions and typical masonry blocks. In the tests, a spherical plastic explosive initiated in the centre was placed at scaled distance of 2.9 m/kg1/3, so that moderate damage would be caused on the wall. In order to assess the performance of the explosive, pressure gauges were placed at the wall and at different distances from the explosion. Additionally, vibrations were monitored with seismographs in the far field and a high-speed camera was used to estimate the shock wave velocity during the tests. The resulting damage has been evaluated on 13 points of the external wall of each box using a rebound hammer. Damage maps have been drawn for each wall based on these measurements and damage has been assessed inside the box considering the fragments mass launched during the test. The use of external metal mess leads to a decrease of 34 per cent on damage of the external wall and 38 per cent reduction of spalling. The use of a film in the inner wall provides a strong reduction on spalling.CITATION:López, L M, Segarra, P, Castedo, R, Sanchidrián, J A, Navarro, J, Santos, A P and Chiquito, M, 2015. Performance of different constructive solutions against explosions in full-scale masonry walls, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 819–824 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By M. Meckkey El Sharnouby

In this paper, the results of full-scale field testing of reinforced helical pulldown micropiles (RG-HSP) installed in clayey till soils and resting on sandy soils are presented. Piles were tested under monotonic and two way cyclic lateral loadings. Effect of different loading setups on the results is demonstrated. The factors affecting the piles' performance are discussed. It was found that under monotonic loading the piles were able to sustain displacement up to 50% of the grout shaft diameter. Under low cyclic loading levels, the piles did not suffer degradation in the performance. Also, the degradation rate during cyclic loading increased with the increase of the load level. The experimental results show that the reinforced helical pulldown micropile is a reliable foundation option for lateral monotonic and cyclic loading applications.

Jan 1, 2011

By Willy Ank de Morais

Este trabalho analisou o caso de emprego de um consumível constituído de aço carbono (ER 70S3) para realizar a soldagem de tubos ASTM A333, empregados em baixas temperaturas, ao invés de empregar consumíveis especiais especificados para emprego em baixas temperaturas, tal como o ER 80S Ni2. Os três pontos centrais considerados neste trabalho foram: (1) compatibilidade entre os materiais envolvidos; (2) análise das características específicas do aço, no grau empregado e do projeto da tubulação e; (3) longevidade da linha, que pode ser prejudicada a longo prazo pelas variações químicas dos metais envolvidos que poderiam induzir corrosão localizada.

Oct 30, 2017

By Greisson Peixoto Rangel

A variação da resistência à compressão de argamassas geopoliméricas foi estudada em função da razão ativador/precursor e da molaridade da solução ativadora. As argamassas estudadas foram confeccionadas com metacaulim (precursor) ativado com solução composta por hidróxido de potássio e água destilada, e areia normal brasileira. De acordo com os resultados, a resistência aumenta com a diminuição da razão ativador/precursor e com o aumento da molaridade da solução ativadora. Além disso, os valores encontrados condizem com os presentes da literatura e com possíveis aplicações para argamassas de múltiplo uso.

Oct 30, 2017

By S Servant

In the mine of this study, cemented hydraulic backfill is placed under the form of a slurry at a percentage of solid by weight varying from 50 to 65 per cent. This slurry settles and cures in the stope. During this process an important amount of water must be drained from the stope. Field observations in the case studied here show that the geometry of the drains system has a significant impact on the drainage of the stopes. The mode of filling produces a backfill showing an evident stratification typical of a sedimentation process. In situ observations on this material show that this stratification translates into a very strong heterogeneity in the physical properties of the cemented backfill. This heterogeneity should affect the hydraulic conductivity of the backfill in the stope. In order to study this aspect, finite element simulations were performed. This paper presents the results of these simulations, where the impact of this stratification on hydraulic conductivity is related to the performance of the backfill drainage system for various geometry. This preliminary study is aimed at providing a better understanding of the role of the drains in the dewatering process of the backfilled stope in the case of this mine.

Jan 1, 1998