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By T. H. Jeffers

The Bureau of Mines conducted a laboratory investigation of copper electrowinning from electrolytes produced by solvent extraction. The purpose of the research was to gain a better understanding of the fundamental relationship between copper electrowinning conditions, anode corrosion, and cathode purity. Processing variables were evaluated in a cyclic semicontinuous system in which the depleted electrolyte was used to strip copper from loaded organic extractant. For the production of high quality copper cathodes, the electrolyte was dosed with cobalt and stripped of organic solvent extraction reagent. An optimum cobalt addition of 60 ppm, and removal of the entrained extractant with activated carbon provided the best conditions for electrowinning copper containing the least amount of lead and controlling anode corrosion. As little as 13 ppm of the entrained organic extractant, LIX 64-N, significantly accelerated anode corro-sion. However, the addition of 1,000 ppm of organic diluent kerosine did not affect anode corrosion. After cobalt dosing and removing the entrained extractant, cathodes containing less than 2 ppm lead were consistently electrowon at widely varied current densities, electrolyte copper and acid concentrations, and temperatures. Dosing of the electrolyte with selected impurities including magnesium, aluminum, manganese, and iron did not affect the cathode purity. However, 0.05 giL of chloride ions markedly increased anode corrosion and the sub-sequent transfer of lead to the cathode copper.

Jan 1, 1985

By Marcos Paulo Kohler Caldas

Após a edição da RoHS Directive 2002/95/EC, diretiva que entrou em vigor em 1º de julho 2006 proibindo a utilização de seis substâncias perigosas: chumbo, mercúrio, cádmio, cromo hexavalente, bifenilos polibromados e éteres difenil-polibromados, fabricantes de equipamentos eletroeletrônicos passaram a utilizar soldas livres de chumbo (lead free) para montagem de suas placas de circuito impresso. A SAC 305 é um tipo de solda muito utilizada pelas empresas fabricantes de placas de circuito impresso. O presente trabalho visa caracterizar este tipo de solda verificando sua composição e identificar se a mesma se encontra livre de elementos perigosos ao ambiente. Avaliou-se a extração de metais como Ag e Sn através de digestão ácida em água-régia e rota HNO3 a temperatura ambiente. A composição do licor lixiviado foi caracterizada por espectrometria de emissão óptica com acoplamento de plasma induzido (ICP-OES). Os resultados indicam que a solda SAC 305 atende a RoHS, possui 2,7% Ag, 96,4% Sn e 0,9% de outros metais e a melhor rota para extração de Ag foi a HNO3 e para Sn foi a água-régia.

Aug 7, 2018

The rapid advance in the adaptation of scientific knowledge to the treatment of ores, resulting in improved chemical and metallurgical processes, has enormously increased the possibility of working lodes profitably, which a few years ago were passed over as unpayable. By the discovery of chlorination, and later of "Cyanidation," by the highly improved methods of concentration, and by the rapid advance in our knowledge of smelting (for which we are greatly indebted to Americanmetallurgists), and by the gradual replacement of scientifing principles and enlightened management, for rule-of-thumb methods formerly in vogue, many large low grade bodies have been opened, and are now paying dividends, which were,twenty years ago, looked upon as hopelessly unpayable. It has been more especially in these large low grade ore bodies, that modern methods have been benefical; for small lodes must be rich to pay at all, as they cannot be worked on the same gigantic scale, but even in these a percentage of metal is saved which formerly was absolutely lost.To make these large deposits remunerative it is, however necessary to try and find the point of greatest economic advantage, to handle the ore in vast quantities, to erect huge plats to treat it, to substitute automatic appliances for hand labour as far as possible, and to combine several processes supplementary to one another, so that ore which is not amenable to one process, shall be saved, by another; and by doing...

Jan 1, 1901

By Fernando Kameoka

Desde o final da década de 90, com o desenvolvimento de novos parâmetros industriais para a fabricação de produtos eletroeletrônicos criou-se o conceito de obsolescência programada. Como consequência deste comportamento mercadológico e novos parâmetros de consumo, o volume de resíduos de equipamentos eletroeletrônicos gerado pelo descarte indiscriminado de produtos ainda em condições de uso tem atingido patamares alarmantes, tornando-se assim um grave problema ambiental. Com a Política Nacional de Resíduos Sólidos, estudos sobre a logística reversa dos resíduos provenientes de equipamentos eletroeletrônicos revelam-se promissores devido à presença de metais com alto valor de mercado, o que viabiliza economicamente os processos de reciclagem destes resíduos. Quando se trata da recuperação de metais e de reagentes, as rotas envolvendo etapas hidrometalúrgicas oferecem um grande benefício em relação às soluções existentes devido à não liberação de gases tóxicos durante o processo. No entanto, para a recuperação de cobre e alguns metais nobres as rotas hidrometalúrgicas tradicionais têm-se mostrado ineficientes devido à presença de ferro nos resíduos. Por esta razão, este trabalho tem como objetivo realizar estudo cinético da lixiviação de ferro de forma seletiva para a recuperação de outros metais. Foi analisado o processo de lixiviação em ácido sulfúrico na concentração de 2M, variando tempo e temperatura, com o intuito de avaliar a extração seletiva do ferro e viabilizando assim os processos subsequentes de recuperação de cobre e metais nobres através de extração sólido-líquido ou líquido-líquido. Os resultados apontam para extrações de ferro em solução de ácido com índices de pureza acima de 95%.

Aug 16, 2017

By Julio Cezar de Sousa Zorzi

Aços com teor de Mn entre 15% e 30% apresentam ductilidade excepcionalmente alta para sua elevada resistência mecânica, devido à ocorrência de transformação de fases (efeito TRIP) e/ou à formação de maclas de deformação (efeito TWIP) na microestrutura predominantemente austenítica. A adição de Mn ajuda a manter a austenita até a temperatura ambiente, evitando a sua decomposição após o recozimento aplicado depois da laminação a frio. O objetivo desse estudo foi avaliar o efeito da temperatura de recozimento na microestrutura e nos valores de propriedades mecânicas de um aço com 17% de Mn, por meio de simulações piloto das etapas de processamento industrial utilizando dilatômetro e simulador termomecânico do Centro de Pesquisa da Usiminas. Observou-se que o aumento na temperatura de encharque durante o ciclo térmico de recozimento contínuo promoveu a reversão completa da martensita a’ para austenita. Além disso, a alteração desse parâmetro praticamente não afetou o limite de resistência e o alongamento total do aço, embora tenha reduzido significativamente o limite de escoamento.

Jul 30, 2018

By Gislan William Guimarães

Neste trabalho avaliou-se o efeito de diferentes ciclos térmicos na microestrutura e propriedades mecânicas de um aço Dual Phase revestido por imersão a quente, da classe de resistência de 800 MPa, a partir de simulações em escala piloto no equipamento HDPS (Hot Dip Process Simulator), ensaios dilatométricos, tração à temperatura ambiente e flangeamento. Nas simulações de recozimento contínuo foram experimentadas duas temperaturas de encharque no recozimento intercrítico (740°C e 780°C) e três temperaturas de patamar isotérmico no resfriamento rápido (610°C, 560°C e 510°C). A caracterização microestrutural evidenciou que a temperatura de encharque de 740°C não foi suficiente para dissolução completa dos carbonetos formados na laminação a quente, resultando em frações reduzidas de segundo constituinte. Com isso, o limite de resistência mínimo de 800 MPa não foi alcançado. Além disso, os resultados de ductilidade e flangeamento se mostraram aquém dos obtidos nas simulações com encharque a 780°C. Nas simulações com temperatura de encharque a 780°C e isotérmicas de 510°C e 560°C no resfriamento rápido foi atendido o limite de resistência mínimo, com capacidade de expansão de furo ligeiramente superior à obtida nas simulações com encharque a 740°C.

Aug 16, 2017

By Marcus Vinícius da Silva Jardim

Neste trabalho foi estudada a recuperação de hastes de sondagem por meio do processo de soldagem por fricção, assim como as propriedades mecânicas obtidas neste processo. As amostras foram retiradas em tubos de aço SAE4130 trefilados sem costura no diâmetro externo de 88,9mm, 5,5mm de espessura de parede e com 300mm de comprimento total. Foram realizados ensaios metalográficos e mecânicos nas amostras do tubo com o objetivo de verificar e comparar as características do tubo em estado de entrega com os resultados obtidos na junta soldada. A junta soldada por fricção apresentou uma microestrutura constituída de bainita inferior e martensita na região da solda. Na Zona Termomecanicamente Afetada – ZTMA observou-se a presença de Bainita, ferrita e perlita. Em consequência das microestruturas obtidas, o valor de dureza na solda por fricção foi maior em relação à ZTA e ao metal base, o que resultou em rompimento na região do metal base durante o ensaio de tração. O método de soldagem por ficção mostrou-se eficaz para a recuperação de hastes de sondagem.

Oct 30, 2017

By C. W. Handy

ONE LAW cannot he evaded, the economic law of supply and demand. Silver, like any other commodity, is subject to this law; and its price in the long run is determined by existing conditions. I say "in the lone run because at times silver has appeared to mope contra to basic coalitions. Such movements, however, are, occasioned by the market's attempt to anticipate changes in these governing conditions. If the expected changes materialize then the new market level is justified, but if they do not then the market will revert to its previous status, A striking example of such a move occurred in November when the price advanced over 70, in ten days and then in the next two weeks lost more than it had gained. The reasons for this advance were that the speculative element interpreted certain events as favorable to silver namely, England suspension of the gold standard, higher shat prices, and the Chinese-Japanese crisis. When these expectations proved unjustified the inevitably, elapse followed became the governing conditions had not channel.

Jan 1, 1932

By Andressa Pereira dos Reis Croucillo

O desenvolvimento de impressoras 3D permitiu uma maior produção de peças e próteses médicas provenientes de polímeros termoplásticos como PLA e ABS, para produção de filamentos. Este trabalho avaliou as características mecânicas de próteses impressas, em determinada temperatura, de filamento PLA. Foram impressos diversos corpos de provas, para a realização de testes de tração, verificando que a configuração com densidade 100%, espessura de 0,4 mm e direção de impressão de 45° e 135° apresentou melhor resultado de resistência mecânica. Realizaram-se também, simulações matemáticas para análise de resistência à queda e flambagem. O conjunto de testes físicos e matemáticos determinou que o PLA não atendeu os requisitos para aplicação deste como próteses.

Oct 30, 2017

By B. C. Slocombe

A large derelict inner city site was regenerated for use as a distribution warehouse. Difficult topography and soils conditions required the adoption of a combination of specialist geotechnical processes. Particular attention was paid to the preparation of the site, programming and capabilities of each technique as additional soils information became available.

Jan 1, 1989

A new series of reports called ?Mineral Perspectives" (MP's) has been initiated by the Bureau of Mines with the publication of MP-1 titled, "Far East and South Asia" by K.P. Wang and the staff of the Bureau of Mines. This new series parallels the creation of the recently announced "Minerals Commodity Profiles" (MCP?s). Both series are designed to provide current information on important sectors of the mineral economy to assist professionals in government, industry, and education in monitoring supply-demand relationships that have significant impact on our domestic economy as well as on the international scene. The orientation of the "Mineral Perspective" series is a geographic one which examines the mineral situation of a region or a country. The "Mineral Commodity Profile? series examines individual mineral commodities. They are in this sense complementary.

Jan 1, 1977

Compagnie Miniere Esperance (CME), a mining company based in French Guyana, operates a gold primary ore body in open pit. The ore is processed through crushing, grinding and gravity separation. Tailings are stored in a ?fine? pond. Analyses of the fine ponds proved a residual gold grade sufficient for a chemical treatment. However, direct cyanidation would require a too large installation, regarding the local conditions (accessibility, supplying and rainforest meteorological conditions). It has been then decided to test the feasibility of a pre-concentration using flotation. Lab tests have been carried out by SGS Lakefield (Canada) in March 2007, which proves the technical feasibility. Therefore, CME asked Caspeo to: ? Carry out an on-site flotation pilot campaign. ? Design an industrial flotation circuit. The tailings reprocessing will contribute to a better tailings management and a dry up of the gold resource, limiting the risk of illegal mining after remediation of the CME site. CME MINE The Esperance gold mine is located in French Guyana, in the vicinity of several gold deposits as Omaï, Rosebel or Camp Caïman, holded by Iamgold and Newmont. These main gold deposits are located on the figure 1. Esperance was put into operation in the early 90?s. The first years were devoted to the mining of alluvial gold in the gravel of the Esperance Creek. Since then, operation was led in the primary gold deposit. Annual production is on average 254kg for a total production in fifteen years of 4300kg. Geology Esperance deposit is located in the greenstone belt of the Guyana Shield. Mineralization is in tectonic contact between sedimentary basin of Maroni and a granitic massif. Clastic series, composed of conglomerate and lamina sandstone, overlie a volcano-sedimentary basement (series called "Paramaca"). The area is strongly folded by shear movements, resulting from granite deposit. Gold is in interlacing quartz veins intersecting the clastic series. Gold is present in association with pyrite. Other elements, as silver or arsenic, are in negligible quantity. Exploitation The Maroni River is the only access to the Esperance mine. Only the saprolite and a part of the transition rock are extracted in the open pit. Excavation works are done using shovels Hyundai 450 (4 units) and haulage works using articulated dumpers Terex TA35 (4 units). These two sorts of equipments are presented figure 2. Mill The mill is composed of crushing and grinding processing plants. After gravity concentration, both plants produce tailings that are stored in two ponds: the first pond contains coarse product which segregates the particles crushed to 2mm upstream and settled clays downstream; the second pond contains the fine product made of particles ground to 200µm. These two ponds, bordered by dams and diversion canals, are located on former alluvial sites of Esperance Creek (see figure 3). [ ] The CME mill is currently producing gold concentrate, with a global recovery of about 67%. The ore is crushed by one jaw crusher and two hammer crushers. The ore then passes through a Knelson KC 48 gravity concentrator, producing a first gold concentrate. The

Jan 1, 2009

Lignite deposits of Central Otago Miocene Dunstan Formation accumulated on a broad alluvial plain and on deltas that flanked a large freshwater lake. The regional subsurface distribution and configuration of the lignite-bearing strata are identified within the context of depositional systems and placed into a genetically defined stratigraphic framework. The stratigraphic and depositional models constructed, should form an integral part of the geological assessment process to guide future regional or mine based lignite drilling programmes. Further testing and evaluation of the commercialy important lignite deposits in the Blackstone and Roxburgh Coalfields are required to adequately characterise the lignites and their geological setting, particularly to select methods of mining and wise uses of the lignite.

Jan 1, 1992

By R. A. Gee, G. B. Ashton, S. T. Warren, P. N. Groves

Northside Storage Tunnel provides 500 megalitres (Ml) (130 million gallons) of storage capacity to capture stormwater/sewage overflows into Sydney Harbour. The6.6 m diameter TBM driven tunnel traverses Middle Harbour 85 m (280 ft) below sea level and through a sandstone/shale rock mass, highly disturbed by stress relief, 20 m(65 ft) beneath the base of the sediment filled palaeochannel. Target limits for inflow, groundwater drawdown and settlement of the valley beaches were achieved by systematic forward grouting from the TBM. Support included rockbolts, sets and shotcrete to carry rock loads, control block instability and spalling and to provide durability and serviceability. This paper describes the tunnelling and grouting works and their effectiveness.

Jan 1, 2001

Developments in the technology of explosive production and deliveryallow a greater amount of flexibility in rock fragmentation by blasting. The rock fragmentation efficiency of an explosive is currently given by a rating which is determined by the explosive manufacturers using proprietary formulae and methodology. Hence, comparison of explosives from different manufacturers may be misleading. Modeling of explosive energy, using a thermochemical code such as CHEETAH provides an objective standard by which the likely performance of different explosive formulations can be determined. Such modeling can be used for optimisation of explosive composition to match specific rockfragmentation objectives.

Jan 1, 2001

By D. Su

This paper presents the details and results of a preliminary investigation into the response of borehole pressure cells (BPCs) in soft coal. Two parallel approaches, laboratory calibration and nonlinear finite element simulation, were adopted for deter- mining the BPC K-factor, which was defined as the ratio of cell pressure change to the corresponding change in external pressure. Results from both the laboratory calibration and the nonlinear finite element simulation revealed a nonlinear response of cell internal fluid pressure to external loading. The K-fact& also is shown to increase with increasing setting pressure and decreasing medium modulus. -Depending on the setting pressure, the K-factor for coal having a Young's modulus of 1.6 x lo5 psi ranges from nearly 1.2 at 2,000 psi of external pressure to 1.485 at 8,400 psi of external pressure. The improved under- standing of BPC behavior leads to the more accurate calculation of BPC K-factor in coal which significantly improves the correlation between pillar pressures measured in underground coal mines and those predicted by nonlinear finite element simulations of these pillars.

Jan 1, 1990

By Thomas W. Camm

The U.S. Bureau of Mines has developed a system for estimating mining and processing costs as a function of process feed rate with the objective of applying this system to abandoned mine tailings and to evaluate the benefits, if any, of metal recovery. Cost analysis was applied to the mine wastes of Smelterville Flats: an extensive area of mine tailings in the Bunker Hill Superfund Site with high concentrations of lead, zinc, and other sulfide minerals. Results from previous site characterization and metallurgical processing studies were used as the input for the cost analysis. This analysis indicated that processing this site at an optimum production rate of 3,500 short tons per day (st/d) could generate a positive cash flow.

Jan 1, 1993

The only economically significant deposit of dolomite in New Zealand is at Mount Burnett, in north-west Nelson. The dolomite, associated with marbles and schists, is complexly deformed, and is of Paleozoic age.A very large quantity is present, although the recoverable amount is to some extent limited by the difficult terrain.Physically the quality of the dolomite is excellent. It is a tough, durable, fine grained rock. Chemically it is a little more variable. The range and frequency o~ the more important impurities are illustrated by hlstograms, as is the "dolomite factor"-a measure of the amount of the mineral dolomite in the rock. lbe dolomite factor averages 84 per cent, the remainder of the rock consisting largely of calcite. Quarrying, milling, production, and uses are described. In 1966 production reached 13,250 tons.

Jan 1, 1969

By F Farías, D Villa

Codelco’s Salvador Project has been operating a block/panel caving mine for more than 50 years. This underground mining method dynamically mixes the ore and dilution. As a result, forecasting grades is difficult and achieving 100 per cent extraction of the reserves is practically impossible. A substantial volume of the ore mixed with dilution becomes remnant ore and remains to be subsequently extracted.A potential open pit mine is under evaluation at Codelco’s Salvador Project, which includes the extraction of remnant ore post-block caving extraction. An effective methodology has been implemented to estimate what is left behind once the underground mine has closed. A new mixing method using the Cellular Automata (Alfaro and Saavedra, 2004) approach has been used to allow estimation of the remnant ore with a sufficient level of confidence to be included as part of the open pit reserve.A remnant block model is created using elements such as in situ block model, drawpoint layouts, historical production records and the drawpoint extraction. Using this information, simulations of the extraction of the mine by month from 1959 to 2019 were completed, using different mixing scenarios and trying to replicate the tonnage and grade extracted.Finally, the remnant block model is categorised using a score card with four inputs to assess the risk of the estimation of this material into a category class (measured, indicated and inferred).CITATION:Villa, D and Farías, F, 2016. Remnant ore model generation and categorisation post-block caving extraction at Salvador Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 461–470 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016