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By D. J. Carney, R. L. Stephenson

A sampling technique has been developed for procuring a sample of sinter representative of the entire depth of the sintering bed. The sampling method involves the use of an open-bottom metal basket that rides on the grate of the sintering machine and when removed contains a sample of the sintered product. Additional data have been obtained to indicate that the tumbler test is a suitable means of measuring sinter strength. IN the last few years additional sintering facilities have been installed in both the Pittsburgh and the Chicago district of the United States Steel Co. Since the construction of these sintering plants made possible the use of higher percentages of flue-dust sinter in our blast-furnace burdens, it became important to study means of controlling the quality of sinter to obtain optimum results in the blast furnace. For controlling an operating process, it is necessary first to establish standards by which the quality of the product can be judged. For sinter, it appeared that an important property was its strength or its resistance to degradation during transportation and charging into the furnace. Consequently work was undertaken to establish a standard for sinter strength that could be used both for controlling sintering-plant operations and for correlating sinter quality with blast-furnace performance. The first problem in setting up a standard was that of procuring a sample that would be representative of the sinter made under any particular set of conditions at the sintering plant. Since the United States Steel Co. sintering plants discharge the finished sinter either into a large pit or onto a rotary cooler, the sinter becomes inseparably mixed with material sintered 2 hr before or 2 hr afterwards. For this reason the exact identity of the sinter is lost. A sample selected as the cooler is discharged, or as the sinter is removed from the pit, cannot be said to be truly representative of the sinter made at any specific time. Sampling The first attempt to procure a sample that would be representative of a specific sinter mix and of specific operating conditions was made by stopping the Dwight Lloyd sintering machine and removing an entire pallet full of sinter. This method, however, proved very difficult to perform and interfered considerably with the operation of the plant. To overcome this difficulty, a sampling method was devised by technologists at South Works enabling them to secure, without interrupting the sintering operation, a sample of about 1 cu ft of sinter, representative of sinter for the full depth of the sintering bed. The South Works method involves the use of a steel-frame-work basket. A typical basket is shown in Fig. 1. The basket has been used both with and without crossbars along the bottom. As long as the crossbars are in the same direction as the grate bars on the sintering machine they do not interfere with the sintering process. The basket is set on an empty grate of the Dwight Lloyd sintering machine before it passes under the swinging feed spout, see Fig. 2. When the basket is removed after it has travelled the length of the sintering machine, it contains the sample. Just before the basket is removed, the sinter is scored and chipped to facilitate removal of the sample from the sinter bed. A view of the basket after its removal is shown in Fig. 3. Although the sampling method was originally designed for use on a Dwight Lloyd sintering machine, it can also be used on the Greenawalt type of machine. When used on the Greenawalt-type machine, the basket is placed on the sintering grate before the charging car passes over it, and finally it is removed just before the pan is dumped. Testing After a method of obtaining a representative sample of sinter had been developed, the next step was to select a method of measuring its strength. The irregular shape and size of the sinter pieces precluded the use of a simple compression test for determining strength; consequently, the shatter test and tumbler test were investigated. To perform the shatter test, a sample of sinter, approximately 5 lb, is dropped from a hinged-bottom box at a height of 3 ft onto a steel plate. The broken sinter is sieve-analyzed after a specified number of drops. The tumbler test is performed with the use of a standard ASTM coke-tumbling drum. The drum is 3 ft in diam and is equipped with two lifter bars diametrically opposite one another on the inner periphery of the drum. The drum is rotated at a speed of 24 rpm for 200 revolutions, and after tumbling the sample is sieve-analyzed. To express as single numbers the results of sieve analyses after shattering or tumbling, the method suggested by R. E. Powers1 was employed. This method involved plotting the size of the sieve openings on a logarithmic scale and the cumulative per cent larger than each sieve on a probability scale as described by J. B. Austin.' By interpolating from the plotted data, which in most cases approximated

Jan 1, 1954

By Patzen Wu, Chao-Ming Tsai, Shaw-Chii Wu, Yuan Lin

INTRODUCTION The development of nuclear industry in Taiwan requires an increasing supply of uranium. Uranium recovery from phosphate ores, becomes an important item of the R & D programs. Many countries have already started such a program. USA has set up an industrial-scale production plant; South Africa, Israel, Morocco and other countries have also engaged in the development of extraction technology of uranium from phosphate ores and started setting up the production plant. In Taiwan, a feasibility study of establishing the production plant was started in 1977. A pilot plant was completed, tested, and operated in 1979. The main source material. - phosphate ores is obtained from China Phosphate Company. The annual yield of the pilot plant has been planned to be one ton of ammonium diuranate (ADU). The Health Physics Division of Institute of Nuclear Energy Research (INER), Atomic Energy Council of Republic of China (ROC AEC), is responsible for the radiation safety control of the plant. The purpose of the radiation safety control is to collect radiation safety information of the plant of this type, to evaluate possible radiation hazards to the personnel, and to analyze the radiation safety of the immediate environment adjacent to the plant. Furthermore, the information and experience obtained are used as the basis for applying radiation safety control to the production plant. The main emphases of the radiation safety control are therefore the arrangement of radiation safety control areas and the collection and evaluation of the health physics data. This report includes the past one and half years' experiences of the radiation safety control of the pilot plant, the planning of the production plant with an annual yield of 10 ton ADU, and considerations given in improving the radiation safety control of the production plant. PILOT PLANT AND ITS OPERATION PROCESS The pilot plant occupies an area of 350 m2 and is a two-story rectangular building. Exits are provided by a front and a rear door. An additional small door at the central right side of the building is connected to the maintenance area located outside the main building. The interior of the building is divided into interconnected offices, laboratories and process area (Figs. 1 and 2). A stairway to the process area of the second floor is located in the central part of the first floor. The second floor offices are accessible by the additional front and rear stairways. The main process area of the first floor is furnished with plastic floor, and the second floor with poriferous iron-grid floor. The building is not furnished with centralized air-conditioning system. Individual air conditioners are, however, available to some laboratories. Because the back door of the building is frequently open, the product storage room is provided with a blower to maintain good ventilation. Natural uranium contents of phosphoric acid solution vary in the range from 0.07 to 0.11 kg/m3. The process consists mainly of the uranium concentration cycle and the purification cycle. A flow diagram of the process is shown in Fig. 3. CONSIDERATIONS GIVEN FOR RADIATION SAFETY CONTROL AND THE ESTABLISHMENT OF RADIATION CONTROLLED AREAS The radiation safety control of the pilot plant is carried out on the basis of the considerations listed below:1,2 1) Since the wet process is adopted, and the flow of the radioactive material is confined to closed pipes and containers, air contamination is therefore not too much of concern. 2) The concentrations of radioactive material of the whole process are mostly less than 10 ppm. An exception is the final ADU product after precipitation and centrifugal separation, which contains up to 50% natural uranium. It is therefore necessary to apply radiation safety control to the process area where

Jan 1, 1981

By Fernanda Santos da Luz

Nas últimas décadas, houve um aumento da aplicação de fibras naturais lignocelulósicas (FNLs) como reforços de compósitos poliméricos em diversos setores industriais, principalmente no segmento automotivo. Esse crescente interesse em FNLs se deve não somente aos benefícios ambientais, mas também às vantagens técnicas, econômicas e sociais. Dentre as FNLs, destacam-se as fibras de coco e as fibras da folha do abacaxizeiro (PALF) que são produtos residuais do cultivo de suas respectivas frutas e, por isso, possuem baixo custo e são abundantemente disponíveis. As características físicas dessas fibras se diferem bastante, sendo o PALF caracterizado por suas fibras longas e diâmetro equivalente relativamente baixo. O presente trabalho avaliou o desempenho das fibras de coco e PALF em testes de pullout com o objetivo de caracterizar o comprimento crítico e a adesão interfacial dessas fibras na matriz de epóxi. Os resultados mostraram um comprimento crítico 65% maior para a fibra de coco em relação ao PALF, o que indica maior adesão interfacial do PALF com a matriz epóxi e pode ser atribuída a superfície naturalmente mais rugosa do PALF.

Oct 30, 2017

By Martin Langenderfer, Sergii Chertopalov, Catherine Johnson, Vadym Mochalin, William Fahrenholtz

The high temperature and high pressure of an explosive detonation can be used for the production of nanomaterials. The controlled detonation of explosive compositions along with the collection and characterization of reaction products encompasses a process known as detonation synthesis. The primary advantage of the method of detonation synthesis is the possibility for producing monocrystalline nanoparticles with diameters of less than 10 nm. In order to successfully synthesize nanomaterials via the detonation process, it is necessary that the explosive detonation is conducted in a sealed environment. This environment when pulled to a vacuum or purged with inert gas such as argon will reduce the oxidation of detonation reaction products. Detonation synthesis testing is currently being conducted in a 1.8 cubic meters (m3) (64.3 cubic feet (ft3)) ellipsoidal pressure vessel consisting of two interlocking half shells. The testing involves the controlled detonation of cast mixtures of Cyclotrimethylene-trinitramine (RDX) and 2,4,6-Trinitrotoluene (TNT) in conjunction with siliceous compounds to produce nanocrystalline diamond and silicon carbide. Alternative detonation environments including the presence of a cooling medium such as water or dry ice to absorb residual, post detonation, thermal energy and enhance the stability of the materials being produced have improved yield. Modifications to the explosive charge composition have an effect on the type and quantity of materials that can be produced. Doping of explosive charges with various organic and inorganic compounds has shown promise in the synthesis of materials that are difficult or uneconomical to produce through other methods. This paper outlines the process development of detonation synthesis facilities. Preparation of the pressure vessel to create a suitable detonation environment for the production of nanomaterials is examined. Formulation of explosive charge compositions and considerations involving test charge initiation are discussed in detail. Experimental results and analysis from initial testing as well as plans for future research are also evaluated.

Jan 1, 2018

By Jadson Barbosa

Corpos de prova de ferro com diferentes níveis de pureza – um de pureza ultraelevada, dois de pureza elevada e um puro comercial – foram testados mecanicamente com diferentes taxas de deformação no âmbito de um antigo projeto. O objetivo era obter a resistência à tração de cada material e verificar a influência das impurezas e da taxa de deformação nas propriedades mecânicas do ferro de pureza ultraelevada. Para melhor compreender os resultados desses ensaios de tração, uma caracterização microscópica detalhada dessas amostras é realizada através deste trabalho. Para tal, foram analisadas as superfícies lateral e de fratura dos corpos de prova de tração no estereomicroscópio e no Microscópio Eletrônico de Varredura (MEV). O dano foi analisado em seções longitudinais ao longo do eixo de tração utilizando o microscópio óptico; a estrutura dos grãos deformados foi investigada por meio da técnica de microscopia EBSD (Difração de elétrons retroespalhados). Microestrutura, padrão de deformação, orientação dos grãos e as características das superfícies lateral e de fratura são então comparadas quanto ao processo de fabricação, nível de pureza e taxa de deformação.

Aug 17, 2017

By Bruno Alves Resende

Em julho de 2010, a linha de Tiras a Quente da Usiminas, planta de Ipatinga, passou a operar com um novo sistema de controle para o laminador de acabamento. Assim, foi necessário atualizar o simulador offline de set up do Trem Acabador, utilizado frequentemente pelas áreas técnica e operacional. Para isso, toda a lógica de cálculo e formulações matemáticas do sistema online foram assimiladas e empregadas no novo simulador. Os resultados das simulações, quando comparados com os valores gerados pelo modelo online, mostraram-se bastante confiáveis. Sendo assim, conclui-se que o aplicativo desenvolvido está apto para ser utilizado como uma ferramenta de simulação offline do modelo de controle do Trem Acabador. Os benefícios potenciais do uso do simulador são: (i) aumento da produtividade por meio da redução de paradas da linha, (ii) melhoria da qualidade final do produto, (iii) redução do número de experimentos na produção e (iv) ajuste dos parâmetros dos modelos de controle. No presente trabalho são apresentadas e discutidas as características do desenvolvimento, da apresentação e da aplicação desse simulador.

Aug 17, 2017

By Thaís da Silva Leite Garcia

Com as mudanças comportamentais do consumidor foi necessário que o mercado automotivo se adaptasse rapidamente para atender exigências relacionadas ao desempenho, qualidade, segurança e impactos ambientais impulsionando a procura de novas alternativas em materiais utilizados e processos. O presente trabalho apresenta a importância do pré-tratamento da superfície da carroceria automotiva e a aplicação do antioxidante para a qualidade do produto final, realizando uma análise dos defeitos gerados por falhas no processo e propondo, se possível, melhorias. O estudo foi realizado em uma empresa automotiva com o foco na fase final do processo descrito acima, onde foi realizada a análise dos dados coletados no período de janeiro a março de 2016. A fim de identificar os principais problemas de falta de camada da cataforese, verificou-se a necessidade do uso de ferramentas de controle para detectar sua causa raiz e encontrou um desvio no pH causado por bactéria no banho. Neste trabalho, verificou-se que a utilização de ferramentas de controle possibilitam a rápida identificação e correção de desvios.

Oct 30, 2017

By Dyego Irineu Silva de Almeida

O presente trabalho teve como objetivo analisar os efeitos dos ciclos de tratamento térmico de recozimento, normalização e esferoidização nas características microestruturais do aço SAE 8620. O aço SAE 8620 é amplamente utilizado na fabricação de engrenagens, pinos e peças onde há exigência de dureza superficial, obtida pelo processo de cementação ou carbonitretação. O aço SAE 8620 é empregado na construção de mecanismos onde a resistência ao desgaste é propriedade mais importante. Para essa aplicação, aços com baixo teor de carbono produzem um núcleo tenaz e os tratamentos termoquímicos conferem as características superficiais necessárias. O espécime original foi caracterizado através dos procedimentos necessários para visualização da microestrutura, bem como as amostras provenientes dos tratamentos térmicos. Sabe-se que o estudo metalográfico de um material é de grande importância para a identificação de suas propriedades, haja vista que essas propriedades estão diretamente relacionadas com a microestrutura que o material possui. Concluiremos que os diferentes ciclos de tratamento térmico, influenciam diretamente nas microestruturas das peças tratadas termicamente, como também na propriedades mecânicas.

Oct 30, 2017

By Gustavo Furigo

A Metalurgia do pó surgiu como uma tecnologia incipiente no início do século passado, e desde então é objeto de inúmeros estudos acadêmicos e industriais, utilizada de forma crescente na indústria metal-mecânica desde a década de 1960. No caso particular de corpos a base de ferro sinterizado e suas ligas um tratamento termoquímico de Oxidação a Vapor, também denominado “Ferróx”, tem sido objeto de pesquisa e estudos por ser uma alternativa muito atrativa do ponto de vista técnico e econômico, melhorando as propriedades tribológicas e promovendo a vedação da porosidade interconectante. Este trabalho tem por objetivo estudar comportamento do tratamento de Oxidação a Vapor em peças de média densidade com composição básica de Ferro, Cobre e Grafite, sinterizadas em condições industriais com diferentes temperaturas. Determinar o comportamento da permeabilidade em função dos parâmetros de processo (temperatura de sinterização, atmosfera e tempo de tratamento de ferrox) e através da Lei de D’Arcy, calcular o coeficiente de permeabilidade (k) dos componentes sinterizados em função dos parâmetros de processo.

Aug 7, 2018

By Marcos Daniel Gouveia Filho

Poço de visita (PV) é uma estrutura de redes coletoras de esgoto onde há a interligação dos fluxos de esgoto. Atualmente a maioria dos PVs em utilização é feito de anéis pré-moldados de concreto; concreto armado; e alvenaria (com blocos de concreto ou tijolos cerâmicos). Devido ao material de sua composição é facilmente sujeito a degradação, ao sofrer desgaste acabam liberando areia, acarretando vários problemas no equipamento de tratamento e no próprio tratamento do esgoto, além dos transtornos públicos ocasionado pela sua falha. Visando solucionar esses problemas, melhorar a qualidade e condições de tratamento de esgoto, busca-se implementar poços de visita produzidos de polietileno, material polimérico com características apreciáveis para essa finalidade, por exemplo seu caráter inerte, peso, resistência e vida útil. Como a estrutura é um protótipo, a influência de defeitos em sua integridade estrutural ainda não se encontra estabelecida. Neste trabalho investiga-se a concentração de tensões em sua estrutura e a influência de defeitos na concentração de tensões, através do método não destrutivo de emissão acústica e simulação computacional.

Aug 8, 2018

By Hans von Michaelis

There has been a renaissance in gold and silver extraction and recovery that has taken place over the last fifteen years, since the price of gold was freed from the $3510~ level. Despite major advances in such areas as carbon adsorption processes for gold recovery, refractory gold ore treatment, crushing and grinding, process control, etc., there still remain several gold and silver mineral processing frontiers. Frontiers related to environmental management present significant challenges especially in the USA. More than ever it is appropriate to optimize total economics by adopting a "systems approach" that integrates mining, mineral processing and environmental management.

Jan 1, 1993

By L. E. Allen, J. F. Abel, D. R. Morgan

The Waste Isolation Pilot Plant (WIPP) is a geologic repository for disposal of transuranic waste and is operated by the U.S. Department of Energy (DOE). The repository is located at a depth of 655 m in the Permian age salt beds of the Salado Formation, 40 km east of Carlsbad, NM. A key component in the design of the WIPP repository is the installation of concrete structures as panel seals in the intake and exhaust drifts after a panel has been filled with waste containers. The DOE has proposed several panel closure design modifications to the EPA. EPA approval of the changes is required since the details of the designs are specified in EPA’s final rule as a condition for WIPP certification. The Environmental Evaluation Group, in its role of providing technical oversight on the WIPP project, has evaluated the proposed modifications. An analysis of this evaluation is discussed.

Jan 1, 2003

By T W. C Stambolie

Longwall mining is a form of underground mining and the principal extraction method for underground coal mining in Australia. The method is used in the mining of both thermal and metallurgical coal. The primary market for thermal longwall mines is that of the export market where price is governed against the Newcastle Thermal Benchmark index (globalCOAL, 2016).Australia’s thermal coal export outlook is considered moderate due to slower demand from major importing countries, as well as slowing domestic production. However, ‘Australia is projected to increase its share of world thermal coal exports and become the world’s largest exporter over the medium term as lower prices, increased domestic use and infrastructure constraints limit growth from other key suppliers’ (Office of the Chief Economist (OCE), 2016, pp 25, 58). On the contrary, and as a result of current global coal price trends, the basic economic principles of underground longwall coal mining are heavily stressed. From a life-of-mine perspective, influencing return on investment is at its greatest during project evaluation and execution. Appropriate and realistic economic assessment is paramount to ensuring the right outcomes are achieved under the current economic challenges.CITATION:Stambolie, T W C, 2016. Thermal coal industry – is longwall mining currently a life-of-mine option in Australia?, in Proceedings Life-of-Mine 2016 Conference, pp 57–61 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By H. R. Manouchehri

In flotation practices, as particles become finer, such as smaller than 20 μm, process efficiency declines markedly. Selective agglomeration of fine particles is a technique to enhance the recovery of fine valuable minerals in flotation circuits. Different agglomerating methods have been introduced and tested. One method that has recently received much attention is to make use of magnetic force to aggregate fine particles. A selective aggregation of fine paramagnetic particles, such as sulfide minerals, can be achieved in the high-intensity magnetic field prior to or during flotation. The method is simple, selective and effective for fine particles and has low operational cost, though a minimum magnetic susceptibility for fine grains is required to promote the process. In this paper, the implementation of the ProFlote magnetic conditioning device in Boliden’s Garpenberg old concentrator in Sweden, where a complex massive sulfide ore is treated, is presented and discussed based on Boliden’s Garpenberg plant. The results showed an increase in the flotation recovery of fine valuable minerals. Zinc (Zn) production was increased by between 1,100 and 1,500 t/a, while salable yearly silver (Ag) production was increased by 1,500 kg. The copper (Cu) grade in the final concentrate was increased by 1 percent, while reductions in its Zn and lead (Pb) grades were obtained. Moreover, considerable reduction in Zn deportment to the final tail was observed

By W. David Menzie

An inventory of the mineral resources of a region is a most desirable basis for planning their systematic development. In the absence of appropriate samples upon which to base a reliable estimate of this inventory, investigators have resorted to a number of indirect approaches; the unit regional value concept forms the basis for one such approach. The produced resources of a region are a function of the inventory multiplied by the degree of intensity (some fraction between zero and one) of development of the resources. A convenient means of expressing this amount is to accumulate the weight and value of resource and to prorate the totals over the area represented by the unit sampled; i.e., weight and value per unit area or tonnes/km.2 and U.S. 1967 $/km.2. When this approach is used for the U.S.A., South Africa and Rhodesia the average value of (log.) U.S. 67$/km.2 for the states of the U.S.A. and South Africa are similar ($55,176 U.S.$67/km.2 and $52,538/km.2 respectively); whereas, Rhodesia is relatively underdeveloped (10,301 U.S.67$/km.2). On the other hand if the individual commodities are used as a basis for comparison, the U.S.A. shows the greatest diversity (67 commodities out of a possible total of 75) with South Africa next (50 commodities) and Rhodesia last with only 26 commodities. Since it is known that area and value are not simply related perhaps diversity is directly related to area. Again the kinds of commodities which have contributed the greatest value to the totals differs, with fuels (petroleum, coal and natural gas) predominating in the U.S.A. totals; whereas, South Africa and Rhodesia obtain their greatest contributions from gold, diamonds (S. Africa) coal and asbestos. In each case the greatest value of resources is produced from sedimentary rocks. As a somewhat different kind of example, consider a single resource (petroleum, the most valuable in the U.S.A.) over a large area (number of sampling units) the U.S.A. by state. Furthermore, assume that the model frequency distribution of the amount of petroleum (tonnes/km.2) is log normal. Then the present production fails to match the model first because 17 states (34% out of 50) have not produced petroleum. Of the remaining 33 states, Louisiana has produced the most (15,177 tonnes/km.2) and the frequency histogram is still skew. A spatial analysis of the distribution of the amount of petroleum by state shows that the samples (i.e., states) are not random; the non-producers and producers tend to cluster. It remains to be seen if this is indeed a true representation of the incidence of petroleum or is a function of the exploration philosophy currently in vogue.

Jan 1, 1977

By Adam J. Szladow

"INTRODUCTIONThe low calorific value and the high moisture and ash contents of run-of-mine (r.o.rn.) lignite limits the utilization of Saskatchewan lignites to thermal power plants in Saskatchewan, Manitoba and western Ontario. On the other hand, the low sulphur content and the low mining cost make lignites potentially attractive for new coal markets, if suitable processes can be found for upgrading. Economic upgrading to a higher quality fuel would make lignites more acceptable for industrial and utility boilers.This paper presents a summary of the process engineering evaluation of coal upgrading technologies conducted in support of a study of selected lignite upgrading processes. The summary presents the relative advantages and offers specific comments on the application of coal upgrading technologies for lignites. ResourcesLignite comprises the largest fossil fuel energy deposits in Saskatchewan. The total resources of immediate and future interest exceed 27 billion tonnes. The measured and indicated lignite resources of immediate interest are large enough to last for over 200 years at the current production rate of about 10 million tonnes per year (Table 1).Saskatchewan lignitedeposits are present in three different geologic formations: (I) the Ravenscrag Formation of Paleocene Age in southern Saskatchewan; (2) the Swan River Formation of Lower Cretaceous Age in central north Saskatchewan; and (3) the Judith River Formation of Upper Cretaceous Age in central west Saskatchewan. The deposits in the Swan River and Judith River Formation are not currently of economic interest.The Ravenscrag deposits are confmed to four lignite basins, namely: the Estevan, the Willow Bunch, the Wood Mountain and the Cypress basin (Fig. 1). The estimated resources of immediate interest in the four basins are over 7 billion tonnes (Table I). These resources include lignite seams at least 1.5 m thick, at depths of less than 45 m.The average quality of lignite varies relatively little between the four basins considering the distance between deposits (Table 2). There is, however, a progressive increase in moisture and ash content, and a decrease in calorific value and carbon content as one moves westward from the Estevan to Wood Mountain and Cypress basins. The Estevan area deposits are of higher rank despite the fact that they are stratigraphically younger than the Willow Bunch deposits (Cameron and Marconi, 1979).In upgrading lignite to a higher quality fuel, it is important to know not only the average proximate and ultimate analysis (Table 2) but also other lignite characteristics influencing the product quality . For example, Figure 2 shows the effect of lignite HIC ratio on the product equilibrium moisture for hydrothermal treatment of lignite. It is apparent that lignites with a higher HIC ratio, or high liptinite content yield much better quality product for the same hydrotreatment conditions. Other examples of lignite characteristics which are important in upgrading include distribution of sulphur forms and mineral matter, maceral composition and degree of surface oxidation."

Jan 1, 1989

By R. M. Fowler, H. L. Hamner

DURING the last 25 years, there appeared in the literature a number of papers describing equipment and operating techniques for the determination of total oxygen in iron and steel. In the early papers, comparatively little attention was paid to side reactions that occur when iron is saturated with carbon at a high temperature in a high vacuum. As more experience was gained with the new method, the limitations appeared. Metals, with a boiling point lower than iron, distilled out of the crucible, condensed in the cooler part of the furnace, and subsequently reacted with carbon monoxide to form oxides and carbon. Aluminum, manganese, and the alkaline earth metals proved troublesome in this respect. Modifications have been devised to overcome the difficulties due to aluminum and manganese, while the alkaline earth metals are not of too much concern as yet to the steel chemist. The reactions of sulphur have received less attention, although it is generally recognized that some carbon disulphide is probably formed. Liquid air traps have been used in some cases to prevent any carbon disulphide from entering the analytical train. Sulphur was not a particular problem at the Union Carbide and Carbon Research Laboratories until the analysis of the irons of higher than usual sulphur contents became necessary. In order to describe the procedure developed for such irons, it will be necessary to first describe the type of vacuum-fusion equipment employed because the operation of vacuum-fusion equipment is an art to a considerable extent. At the Laboratories, vacuum-fusion equipment has been in daily operation since about 1930. Over the years, the evolution of this apparatus has been governed by the versatility required to analyze a wide variety of materials. Since all types of materials from high purity metals to slags are analyzed and, since seldom more than a few samples of one type are analyzed in succession, the apparatus was designed for accuracy and flexibility rather than for speed. A general view of the equipment is shown in Fig. 1, while Fig. 2 shows the relationship of the various parts. In Fig. 2, A is a vertical double-glazed 24X27/8 in. OD silica tube heated with a 20 kva mercury-arc high frequency generator. The tube is closed with a water-cooled brass head attached with de Khotinsky cement. A turret cap fits on this head and is sealed with a 1/8x3 in. "0" ring. The head contains a sight glass and two 8 in. horizontal glass tubes, for sample storage, cemented in with de Khotinsky cement. B is a four-stage Gaede mercury diffusion pump connected to the water-cooled head with a 11/2 in. copper tube through a flange with an "0" ring. The output of the vacuum pump feeds into an automatic Toepler F pump which compresses the gas sample over mercury in the measuring burettes, G and H. There are bypasses in this line for a McLeod gage C and a Piranni gage D, a manometer E, and for initial pumping out of the system with a Cenco Megavac backing-up pump. The reduction crucible shown in Fig. 3 is machined of Tungar Bulb quality (A.G.K.T.E.-2) graphite. The sample is guided into the crucible with the graphite funnel depicted on this figure. The arrangement of the crucible, radiation screens, etc. in the furnace is as follows: A 1 15/16x61/2 in. Alundum thimble, porosity RA-84, with two 1/8 in. holes near the top and opposite each other which take a pair of special tongs used for lowering it in place, is prepared. A 3/4 in. layer of powdered graphite is placed in this Alundum thimble, and the graphite crucible containing 20 g of ingot iron and 0.5 g of carbon is carefully centered on this bed of graphite powder and graphite powder is packed around it to the top of the graphite cru-

Jan 1, 1953

The Australian Constitution specifies certain powers of the Commonwealth Government to be used in its capacity as the national government. Certain of these broad powers result in the Com- monwealth having a facility to play an important part in the development of the mining industry. The State Governments, however, by virtue of their wide powers to regulate matters within the boundaries of a particular State, are more directly involved in the day to day administration and standards of activities of mining operations. In this respect the Common- wealth has something of a dual role because of its "State-like" responsibilities for the mainland Terri- tories. The components of the role that the Common- wealth Government discharges in relation to the mining industry are qualified to varying extents at particular times by the political persuasion of the Government. In absolute terms the components are as follows. 1. Economic management. The Commonwealth's fiscal and monetary policies have an important effect on industry as well as on State finances. In particular, the taxation regime employed by the Commonwealth Government is of direct importance to economic decision-makers in the mining industry. 2. International matters. International trade and commodity matters are, more and more, becoming an everyday part of the conduct of a nation's foreign affairs. 3. Exports. The Commonwealth Government, via the constitutional powers over overseas trade, have exercised varying degrees of control over mineral exports to achieve particular objectives. 4. Foreign capital and investment. Australia in general, and the mining industry in particular, is and will continue to be a net importer of capital. There appears to be bipartisan political agreement in Australia that foreign investment policy must be enunciated to ensure that investors. are in no doubt that Australia welcomes beneficial investment and technology from overseas. 5. Environment and Aborigines. Governments, both Commonwealth and State, have in recent years become more involved in these areas in response to their interpretations of community aspirations. 6. Energy. Access to assured supplies of energy is now viewed, by Governments worldwide, as a desirable asset to ensure the well-being of a nation's people and industries.

Jan 1, 1978

By Gustavo Tressia

Neste trabalho foi avaliada a influência da geometria da câmara de acumulação e da relação de extrusão na fabricação de fios de cobre por meio do processo de conformação contínua, Conform. Dois tipos de produtos foram fabricados, sendo um retangular com menor área de seção transversal e outro redondo com maior área. Para a condição do material redondo, dois tipos de câmara de acumulação foram utilizados, sendo uma de maior dimensão, resultando em maior acumulo de material antes da conformação pela matriz de extrusão. Medições de temperatura foram realizadas na matriz de extrusão. No produto final foram realizados ensaios de limite de resistência à tração, escoamento e alongamento. Ao longo da câmara de acumulação e no produto final foi realizada analise microestrutural e de tamanho de grão. Os resultados mostraram que o aumento da relação de extrusão promoveu aumento da temperatura do conjunto e consecutivamente aumento do tamanho de grão do produto final. Ao longo da câmara de acumulação foi observada uma tendência de redução do tamanho de grão até o produto de saída.

Oct 30, 2017

By Maria Vianna Rigatto

Nesse trabalho, foram realizados ensaios de abrasão do tipo roda de borracha em um aço ASTM A242, com o intuito de verificar se a orientação do desgaste em relação à da laminação influencia no comportamento em desgaste do material. Estes ensaios foram executados seguindo a norma ASTM G65-16. Todas as amostras foram fresadas e lixadas para a realização dos ensaios, além de limpas com acetona para medição da massa tanto antes quanto depois do ensaio de desgaste. Utilizando a massa perdida após o ensaio e considerando um possível desgaste da roda de borracha, foi calculado o volume perdido nos ensaios. Além disso, foi medida a microdureza do aço, nos sentidos transversal e longitudinal à laminação, bem como analisadas as microestruturas nos respectivos sentidos antes e depois dos ensaios de desgaste. Os resultados mostraram que a orientação do desgaste em relação à orientação de laminação possui influência na taxa de desgaste e que no sentido transversal à laminação essa taxa foi 9,6% menor que no sentido longitudinal.

Oct 30, 2017