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By Arnaud-Guilhem de Loze

Este artigo apresenta uma ferramenta de simulação computacional desenvolvida com o objetivo de auxiliar a adoção de melhores práticas de controle do forno durante períodos sem produção. O sistema desenvolvido permite simular as temperaturas do revestimento refratário de um forno de tratamento térmico de tubos em função da evolução da temperatura da atmosfera interna em diferentes cenários. O simulador foi desenvolvido baseado em um modelo matemático dinâmico validado, que utiliza um sistema de equações de transferência de calor discretizadas. Realizou-se a validação desta ferramenta computacional com a utilização de dados reais de uma campanha de medição de temperaturas. A comparação dos resultados apresentou pequeno erro entre simulação e valores reais coletados. A utilização desta ferramenta auxiliou a definição de estratégias de controle do forno durante períodos improdutivos, possibilitando redução do consumo de energia e retomada da produção com garantia da qualidade do produto.

Aug 17, 2017

By J. P. Newell, R. W Storey

This paper describes the development of a continuous float-and-sink process to produce coal low enough in ash content to be suitable for production of electrodes. The cleaned coal had a combined iron and silicon content of 0.239 pct. The efficiency of recovery was 84 pct. AUGER mining is a form of continuous mining in that it completely replaces with a one-cycle operation the older conventional cut, drill, shoot, and load method of mining. Relatively new, having been utilized only within the last few years, it is even more continuous in its production of coal than some other forms of continuous mining being practiced in this country today. There are at present coal recovery augers in operation working along strip-mined highwalls from the outside. This paper will deal with underground mining, specifically with an experiment which was carried out with a machine developed for this purpose. The location of this experiment was in Pike County in eastern Kentucky in the upper split of the No. 3 Elkhorn seam. Coal height was 32 in. and roof conditions were very bad, with 10 in. of soft draw slate coming down with every cut in conventional mining. The coal is high-grade bituminous, excellent for metallurgical coking. Underground auger mining fills a need for a method of recovering coal in thin seams, under bad roof conditions or in split seams. In many cases it might save money by eliminating the handling of excessive quantities of rock. In fact, if the coal can be recovered, as in the case of this experiment, without mixing with any impurities outside the seam, it may be possible to load or ship a satisfactory product with little or no preparation or cleaning expense. The need for some economical method for recovering coal from thin seams is becoming more pressing as the more profitably mined seams are exhausted. Basic Principles of Auger Mining The principles of the auger, or screw conveyor, have long been used in drilling small diameter holes for blasting and other purposes. These same fundamentals apply to large diameter drilling. However, considerably more attention was given to designing a cutting head that would not pulverize the coal and consequently would require a minimum of power to drive it. The head, as designed for this job, consists of a cylinder 25 in. in diam with steel bits set in 3 positions spaced around the forward rim. A conventional coal drill bit, at the head of a bursting cone in the center of the cylinder, trails the forward rim slightly, see Fig. 1. The bursting cone and auger connections are anchored to the cutter barrel by 3 arms spaced at 120". This head design proved to be very satis-

Jan 1, 1953

By J. P. Newell, R. W. Storey

This paper describes the development of a continuous float-and-sink process to produce coal low enough in ash content to be suitable for production of electrodes. The cleaned coal had a combined iron and silicon content of 0.239 pct. The efficiency of recovery was 84 pct. AUGER mining is a form of continuous mining in that it completely replaces with a one-cycle operation the older conventional cut, drill, shoot, and load method of mining. Relatively new, having been utilized only within the last few years, it is even more continuous in its production of coal than some other forms of continuous mining being practiced in this country today. There are at present coal recovery augers in operation working along strip-mined highwalls from the outside. This paper will deal with underground mining, specifically with an experiment which was carried out with a machine developed for this purpose. The location of this experiment was in Pike County in eastern Kentucky in the upper split of the No. 3 Elkhorn seam. Coal height was 32 in. and roof conditions were very bad, with 10 in. of soft draw slate coming down with every cut in conventional mining. The coal is high-grade bituminous, excellent for metallurgical coking. Underground auger mining fills a need for a method of recovering coal in thin seams, under bad roof conditions or in split seams. In many cases it might save money by eliminating the handling of excessive quantities of rock. In fact, if the coal can be recovered, as in the case of this experiment, without mixing with any impurities outside the seam, it may be possible to load or ship a satisfactory product with little or no preparation or cleaning expense. The need for some economical method for recovering coal from thin seams is becoming more pressing as the more profitably mined seams are exhausted. Basic Principles of Auger Mining The principles of the auger, or screw conveyor, have long been used in drilling small diameter holes for blasting and other purposes. These same fundamentals apply to large diameter drilling. However, considerably more attention was given to designing a cutting head that would not pulverize the coal and consequently would require a minimum of power to drive it. The head, as designed for this job, consists of a cylinder 25 in. in diam with steel bits set in 3 positions spaced around the forward rim. A conventional coal drill bit, at the head of a bursting cone in the center of the cylinder, trails the forward rim slightly, see Fig. 1. The bursting cone and auger connections are anchored to the cutter barrel by 3 arms spaced at 120". This head design proved to be very satis-

Jan 1, 1953

By Hans G. Machel

In low-temperature diagenetic environments (0 c T c 60 - 80°C), elemental sulfur forms by six common processes: via (1) inorganic oxidation of H2S by molecular oxygen, (2) inorganic oxidation of H2S by ferric iron compounds, (3) polysulfide disproportion- ation; and via the microbial metabolic actions of (4) colorless sulfur bacteria, (5) colored sulfur bacteria, and (6) some types of thiobacilli. Economically viable deposits of native sulfur usually are formed by only one process: inorganic oxidation of H2S by molecular oxygen. The amount of elemental sulfur is also limited by three common processes that destroy it in low- temperature diagenetic environments: bacterial reduction, bacterial oxidation, and inorganic oxidation. In high-temperature diagenetic environments (80 - 10o°C c T c 150 - 200°C), particularly in sour gas reservoirs, there are seven common processes forming elemental sulfur: (1) SOdH2S reaction, (2) H2S- hydrocarbon reaction, (3) polysulfide disproportionation, (4) catalytic H2S decomposition, (5) C02-H2S reaction, (6) chlorinification, and (7) exsolution of physically dissolved elemental sulfur. Natural processes that destroy or remove elemental sulfur in such settings are hydrocarbon sulfurization, polysulfide formation, and advection. In most sour gas reservoirs, relatively small quantities of elemental sulfur occur as a free phase (solid or liquid). However, elemental sulfur often precipitates in copious amounts from the reservoir fluids via exsolution and polysulfide disproportionation during production of sour gas reservoirs. By extension, elemental sulfur may precipitate from reservoir fluids in relatively large quantities upon uplift and erosion of deep sour gas reservoirs, or from advection of sulfurous fluids into shallower settings via faults or other high-permeability pathways.

Jan 1, 1992

By Thomas Schanz

Current steel market conditions require small investments only to lower operational cost. SMS Concast has developed new products which optimize continuous casting process cost for long product steel production. This paper describes a selection of three products. All three systems are patented (patent pending for CONDRIVE). CONSAFE, a non-radioactive mould level measurement system for reliable mould level measuring on open stream casting CCM’s; CONSTIR-MWS, an improved control software for electromagnetic stirrers which lowers energy cost by 35%; CONDRIVE, a brand new oscillation drive system which provides the features of a hydraulic oscillator, however with a cost efficient electric drive.

Aug 17, 2017

By Ayumi Yoshioka

Os componentes automotivos em geral devem atender a especificações rigorosas de propriedades mecânicas, requisitos de limpeza inclusionária, entre outros. Enxofre e alumínio são dois elementos adicionados ao banho líquido, que têm papel importante na obtenção destas propriedades, mas que dificultam o processo de produção por lingotamento contínuo por favorecer a formação de partículas sólidas de alto ponto de fusão, que podem prejudicar a limpeza inclusionária e provocar a obstrução das válvulas de lingotamento. O objetivo do presente trabalho é analisar e classificar as inclusões de corridas do aço DIN 38MnSiVS6 em escala industrial e avaliar estes resultados em conjunto com os dados de processo de aciaria e com os resultados de simulação termodinâmica utilizando o software FactSage 6.4. Foi observado que as corridas apresentaram tanto sulfetos de cálcio quanto espinélios, mas as primeiras, associadas a uma fração líquida menor na escória, tiveram uma correlação mais perceptível com a má lingotabilidade.

Aug 17, 2017

By D. Eugene Rannels, Yu-Chen Lee, John W. Swisher

"Inhaled dust particles of appropriate size contact cells of the alveolar region.' The acute response to coal dust appears to involve a variety of cell types, including alveolar epithelial cells, interstitial fibroblasts, both resident and recruited macrophages, and cells of the immune system. Direct and indirect effects of dust, which may be mediated by soluble factors,'' can initiate acute and long-term lung injury. While it appears that epithelial cell growth and differentiation, along with integrity of the epithelial basement membrane, may play a role in the long-term response to dust exposure, little is known of the role the alveolar epithelium may play in the progression of injury. The broad hypothesis that underlies these experiments is that short- and long-term consequences of coal dust exposure involve changes in structure and function of the alveolar epithelium and the underlying extracellular matrix. Recent studies show that coal dusts exert direct effects to modify pulmonary epithelial cell-extracellular matrix interactions in vitro.3EXPERIMENTAL PROCEDURESType II cells isolated on day 0 by density centrifugation and differential attachment4 were plated overnight in D MEM containing 10% fetal calf serum before exposure to anthracite dust PSOC 867 sonicated into culture medium (750 ug/mL).3 Synthesis of extracellular matrix proteins was determined on day 3 of primary culture, as detailed elsewhere. 5 Cells were removed from extracellular matrix by extraction with NH4OH and high salt. Extracellular matrix synthesis and fibronectin content were evaluated based on radiolabeling with 3 H-leucine and on Western blot analysis, respectively. Additional analytical methods and calculations are detailed elsewhere.3-5"

Jan 1, 1998

By Murillo Romero da Silva

Ligas com memória de forma (LMFs) são ligas metálicas capazes de recuperar o seu formato e tamanho original após deformação plástica quando aquecidas acima de uma temperatura crítica. Diversos casos de possíveis aplicações paras as LMF têm sido justificados no campo científico, com alguns poucos casos identificados para aplicação em massa, existindo uma ausência na literatura de uma análise crítica da aplicabilidade das mesmas que leve em consideração aspectos industriais e de mercado. Dessa forma, se faz necessário um estudo mais aprofundado que correlacione as ideias científicas geradas com a produção industrial e com a comercialização de LMFs. Nesse contexto, o trabalho visa através de levantamento e análise de patentes e artigos científicos, assim como por contatos industriais, estabelecer uma relação entre o desenvolvimento científico e o comercial das LMFs. Mais de 11 mil artigos e mais de 7 mil patentes foram produzidos nos últimos 16 anos, sendo observado uma tendência crescente da criação de conhecimento de LMF, o qual já vem sendo aplicado na indústria, justificando assim os esforços observados no campo científico. A área biomédica se destaca como a mais bem estabelecida no campo das LMF, com destaque para a utilização das ligas a base de NiTi.

Aug 17, 2017

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

5. Development of Initial Probing System 5. 1 Introduction The preliminary evaluation of a variety of potential methods for initial probing showed that the optical system using closed circuit television (CCTV) and the sonar, or acoustic ranging, system were the most promising. The former is capable of pro¬viding a visual display of the mine passages in a clear, non-smoky environment, and the latter is capable of providing a map of the spatial location of the coal surfaces making up the entries, as well as objects, such as cribs, mining machines, etc., in the passages in both smoky and non-smoky environments. The sonar system used in conjunction with the CCTV in a clear environment can greatly assist in resolving the spatial distribution of objects seen on the TV screen. Further, in a smoky environment the interpretation of the sonar information could be facilitated if some visual information were also available. CCTV systems exist but require some modifications to suit this particular application. The Industrial Hazards and Communications Division of the Bureau has an ongoing program for the development of such a CCTV system. Rather than duplicate this effort in developing a CCTV system, it was decided to evaluate the possibility of utilizing their system for initial probing, while continuing with the develop¬ment of a system which would work in any environment, including the presence of dense smoke. The concept of using sonar for the initial probing of mine passages represents the application of new technology requiring development. The results of such a development effort undertaken during the course of this program are described in the following sections.

Jan 1, 1973

By R. L. Grayson, R. C. Althouse, L. A. Layne, M. J. Klishis

Introduction The researchers combine a detailed microanalysis of accident data and roof bolting field observations to develop new and meaningful risk indices for the roof bolter job classification. These indices incorporate information that has not been used in traditional measures of risk. The significant parameters that these new indices incorporate are the total number of accidents occurring within a particular work activity, the amount of time a miner usually spends performing the work activities in which the accidents occurred, and the average severity of the injuries incurred in the accidents. Being specific for a particular job, they aid comparisons among work tasks performed in the bolting cycle. The indices' specificity provide anew basis for reexamination of training and operational development of miners for specific jobs. Microanalysis The roof bolting microanalysis was performed by examining the empirical data and written summaries for all bolting accidents reported in the West Virginia Safety Information System (WVSIS) for the years 1983-1987. The WVSIS database contained more than 15,000 accident narratives. The microanalysis of bolting accidents covered 2083 reported personal injuries (RPIs). This large number of injuries, performed at an industry-wide level, provides a broad picture of the nature of roof bolting injuries. The analysis focuses on the activities associated with the cyclical routines of the roof bolting process. For this analysis, roof bolting tasks were categorized into work routines based on the sequence of work activities performed by roof bolters. Four work routines were identified within the overall bolting cycle. And these routines comprised 70% (1217) of all roof bolting accidents at the face. The routines include: face area preparation; tramming, positioning and setting the automated temporary roof support (ATRS); drilling holes; and installing bolts. The types of injuries most common within a routine and the average severity of those RPIs were also identified. Table 1 gives a breakdown of the percentage of accidents by the bolting routines. Another 19% of the roof bolting RPIs cannot be classified in a particular routine because of the vagueness of the narratives. However, it was clear that these accidents involved drilling holes or installing bolts. These results are consistent with previous research. It identified drilling and bolting, followed by tramming, as the most frequent sources of injuries (Helander, Krohn & Curtain, 1983). [Table 1-Accidents by bolting routines at the face Accidents Bolting routine Percent Number Face area preparation 18.2 222 Tram, position, ATRS 23.3 284 Drilling holes 34.2 416 Installing bolts 24.2 295 Total 1217] Roof bolter operators were involved in 82% (1706) of the 2083 accidents. The RPIs incurred by classified roof bolters occurred largely on working sections (95%) and at the face area on the working section (75%). Approximately 23% of the 1706 roof bolter RPIs occurred during tasks which were not part of the bolting cycle. These included belt utility work, providing supplies and section moves. Miners in other job classifications who were involved in roof bolting accidents accounted for the remaining 18% of the 2083 roof bolting RPIs. Among this group were section utility men and general laborers (41%), section machine operators (38%), and electricians and mechanics (11%). Another 9% were performing on-section supervisory functions. Face area preparation Face area preparation work led to a substantial number of injuries, although it accounted for the lowest number of injuries of the four routines. Several tasks were associated with the injuries incurred in this routine. Table 2 shows the percentage of injuries associated with face area preparation. [Table 2- Accidents occurring during face area preparation 26.6% Setting temporary and supplemental supports 24.8% Scaling roof and ribs 21.2% Installing ventilation devices 15.8% Handling supplies and materials 11.6% Miscellaneous tasks] The injuries commonly involved overexertion and 'struck by' falling coal and rock. Handling materials often led to overexertion injuries. Nearly 66% of the scaling-related injuries and about 33% of the injuries incurred during the setting of temporary supports involved 'strikes' by equipment, materials, top and rib. Tramming, positioning and setting the ATRS During tramming operations, workers were often struck by components of the machine and hit by loose roof and rib. Poor footing also led to slips, sometimes against the moving machinery. Table 3 gives a breakdown of accidents in this routine. Control levers were a significant problem in this routine.

Jan 1, 1993

By S. R. McCutcheon, D. R. Lentz, W. S. Downey

"Abstract - The Little Falls member of the Nepisiguit Falls Formation is situated in the northern part of the Brunswick Belt of the Bathurst Mining Camp and has been interpreted as the distal equivalent of proximal tuffaceous rocks that host the stratiform Brunswick No. 12 and No. 6 Pb-Zn massive sulfide deposits. It comprises fine-grained, greenish-gray tuffaceous sandstone in the lower part, and coarse-grained, crystal-rich tuffaceous sandstone in the upper part. Petrographic evidence suggests that these rocks have a turbiditic origin. The Little Falls member is underlain by the Vallée Lourdes member, mainly composed of relatively shallow-water calcareous rocks, and is conformably overlain by Mn-rich sedimentary rocks, mainly red argillites that host the Tetagouche Falls Mn-(Fe) deposit. All these rocks are considered to belong to the Nepisiguit Falls Formation, part of the Ordovician Tetagouche Group. Whole-rock geochemical data from the fine-grained tuffaceous sandstone and coarse-grained tuffaceous sandstone indicate that the two units of the Little Falls member are distinct. Zr and TiO2 contents, and total rare earth element (REE) values are higher in the coarse-grained unit (average Zr/TiO2 = 0.040, average SREE = 247 ppm, n = 6) than in the fine-grained unit (average Zr/TiO2 = 0.048, average SREE = 158 ppm, n = 17), which can be attributed to the variation in crystal content between the two units. Both units are HREE-enriched and have elevated La/Yb relative to the typical Nepisiguit Falls Formation. Overall, the geochemical data combined with evidence from the bounding units suggest that the Little Falls member was deposited in relatively shallow water, possibly in a near-arc environment. The relationship of volcanic facies within the Nepisiguit Falls Formation and the geochemistry of these facies indicate strongly that fine grained, reworked tuffaceous rocks, regardless of whether they are the distal equivalents of proximal tuffaceous rocks, are not associated with the major ore-bearing horizons of the Bathurst Mining Camp. Sommaire - Le Membre de Little Falls de la Formation de Nepisiguit Falls se retrouve dans la partie nord de la Ceinture Brunswick du Camp Minier de Bathurst ou elle a été interprétée comme l’équivalent distal des roches tuffacées proximales hôtes des gisements de sulfures massifs de Pb-Zn stratiformes Brunswick No.12 et No.6. Il consiste en grès tuffacé à grains fins gris verdâtre dans sa partie inférieure et en grès tuffacé à grains grossiers riche en cristaux dans sa partie supérieure. Les données pétrographiques suggèrent que ces roches ont été déposées par des courants de turbidité. Le Membre de Little Falls repose sur le Membre de Vallée Lourdes, lequel consiste principalement en roches calcareuses déposées en eau relativement peu profonde; il est de plus recouvert en concordance par des roches sédimentaires manganifères, lesquelles consistent principalement en argilites rouges hôtes du gisement de Mn-(Fe) de Tetagouche Falls. Toutes ces roches appartiennent à la Formation de Nepisiguit Falls, laquelle fait partie du Groupe de Tetagouche, d’âge Ordovicien. Les données lithogéochimiques des grès tuffacés à grains fins et à grains grossiers indiquent que ces deux unités du Membre de Little Falls sont distinctes. Les teneurs en Zr et en TiO2, ainsi que la teneur totale en Éléments des Terres Rares (ÉTR) sont plus élevées dans l’unité à grains grossiers (Zr/TiO2 moyen = 0.040, SREE moyen = 247 ppm, n = 6) que dans l’unité à grains fins (Zr/TiO2 moyen = 0.048, SREE moyen = 158 ppm, n = 17), ce qui pourrait s’expliquer par la variation de la quantité de cristaux dans chacune de ces deux unités. Chacune de ces deux unités présente un enrichissement en ÉTRL ainsi qu’un rapport La/Yb relativement plus grand que ce qui est typiquement observé dans la Formation de Nepisiguit Falls. Les données géochimiques considérées conjointement à l’information provenant des unités adjacentes suggèrent que le Me"

Jan 1, 2006

By Carlos Berlini Filho

As inclusões exercem um papel fundamental na lingotabilidade dos aços produzidos em lingotamento contínuo. É conhecido na literatura o efeito da composição das inclusões na formação de obstruções em válvulas submersas. Contudo, um problema também recorrente no ambiente industrial é o desgaste dos tampões e válvulas submersas do distribuidor, que impede o controle de fluxo de aço para os moldes. O presente trabalho visa avaliar a influência da composição das inclusões na taxa de desgaste de tampão. Foram avaliadas inclusões de aços acalmados ao Si-Mn em corridas que apresentaram diferentes valores de desgaste de tampão. A partir dos resultados obtidos foi possível concluir que a taxa de desgaste de tampão é consideravelmente dependente do teor de MnO das inclusões e que um maior teor de Al2O3 pode contribuir também para reduzir o desgaste.

Aug 17, 2017

By T. H. Courtney, B. R. Murphy

"Nominal room temperature mechanical alloying (MA) has been used to synthesize the high melting temperature NbC and Cu-NbC composites. Elemental powders of Cu and Nb were alloyed in the presence of either graphite or hexane to form nanocrystalline NbC or a Cu-NbC composite. Through control of hot-isostatic-pressing (H/Ping) parameters, we have been able to minimize microstructural coarsening during densijication, and have processed fully dense bulk compacts of both single phase NbC and two-phase Cu-NbC while maintaining a nanocrystalline or near-nanocrystalline structure. These materials generally exhibit high strength and low fracture toughness. However, mechanical properties vary significantly depending upon the Cu content and the method of NbC synthesis (graphite or hexane).INTRODUCTIONMechanical alloying (MA) has been recently used to synthesize a variety of inorganic solids; sulfides (1-2), nitrides (3), borides (4), and carbides (3, 5-8). One advantage of this processing route is that synthesis of fairly high melting temperature materials takes place at what is nominally room temperature. Another advantage is that the structures generated are often nanocrystalline in scale, with attendant interesting properties. The consolidation of these fine structures into near fully dense or fully dense materials while limiting microstructural coarsening is a challenge that has just recently seen limited success (5, 9). We report here on some recent studies of ours dealing with crystallite size and structural analysis of NbC and CuNbC composites consolidated to full density from mechanically alloyed powders. Bulk mechanical properties and their dependence on milling parameters are also presented."

Jan 1, 1994

By Emmanuel Detournay, Charles Fairhurst

A method is proposed for computing (a possible solution of) the ground reaction curve, for use in tunnel support analysis, in cases where the initial stress field is not hydrostatic. Rock around a circular tunnel is assumed to behave as an elasto-plastic material with a Mohr-Coulomb yield envelope.

Jan 1, 1982

By AIME AIME

ORGANIZATION of The Federated American Engineering Societies was effected at the organizing conference of national, local, state and regional engineering and allied technical organizations at the Cosmos Club, Washington, D. C., June 3 and 4. Thus is brought into being the greatest national engineering society in the world. The object of the organization is to further the interests of the public through the use of technical knowledge and engineering experience, and to consider and act upon matters common to engineering and allied technical professions. Prominent engineers from all parts of the country, representing more than 75 engineering societies, with an aggregate membership of more than 125,000, participated in the organization. The constitution as adopted by the conference, calls for the creation of s managing body to be known as the American Engineering Council, and its executive board. The belief was expressed that the entire organization would come to be spoken of as the American Engineering Council. The council is to coordinate the activities of state councils and of local affiliations whenever these activities are of national or general importance or may affect the general interests of engineers. Representation in the council is to be according to membership of the component societies.

Jan 1, 1920

By L. K. Sinclair

In situ leaching of copper has the potential to deliver low-cost recovery for soluble copper deposits of sufficient permeability. In order to provide key inputs for modeling of the in situ leaching process, bench scale test work can be used in conjunction with geochemical software to identify key leaching and precipitation reactions. A case study is presented in which a series of flow-through acid leaching tests were conducted on drill core sections from a porphyry copper deposit without crushing or grinding. Concentrations of copper and other key elements were monitored in the recirculating leach solution over several months. A geochemical model of each leaching test was prepared using Geochemist's Workbench using a combination of diffusion-controlled and reaction-controlled rate mechanisms. Key reactions included leaching of chrysocolla, iron oxides, and plagioclase. The model was able to simultaneously satisfy the evolving chemistry of the recirculating leach solution, mineralogy of the head and leach residue, measured acid consumption, and leaching rates for key minerals reported from previous laboratory studies. Opportunities and limitations for scaling up the model to simulate the commercial wellfield are discussed.

Jan 1, 2015

By J. H. Starkey

SAGDesignTM Testing for grinding mill design was introduced commercially in 2004. Up to January 2008, 18 projects have been completed and 99 samples have been tested using this method. Two papers have been published describing the patented test procedure and one of these shows how the results compare with other grinding test methods. This paper will briefly discuss the theory on which this technology is based, and explain the procedures used to develop the calibration equation. Case studies are also included to demonstrate the effectiveness of the test work being done. These case studies show how the SAGDesign test is being used today: to design new grinding circuits for commercial full scale use; to calculate throughput in existing mills for production planning; and to accurately define grinding mill requirements at the scoping, pre-feasibility or feasibility study stage of project development, in order to economically identify the size and cost of the grinding mills that will be needed for the project. This is important because if the full rec-ommended SAGDesign testing program is done at an early stage in the project, the definitive cost for a guaranteed throughput, grinding mill design (by Outotec if their mills are purchased) is available. New grinding mill design for final engineering will be represented by the test work done on the Climax Molybdenum Project for Phelps Dodge (now FMI) in Colorado, USA. The SAG mill and ball mill for Climax are now in fabrication with project start up in late 2009. Next, the sizing of grinding mills at the scoping, pre-feasibility or feasibility study stage of mine development will be represented by a large metal mining property in Russia. Finally, calculation of the throughput for existing mills will be represented by work done at a base metal mine, in eastern Canada. Test work for designing SAG mills is now done in four laboratories at the time this paper was written. One in the USA at Dawson Metallurgical Laboratories, Inc. in Salt Lake City, two in Russia at the TOMS Research and Design Institute and at the Irgiredmet Research Institute, both in Irkutsk, and a fourth mill has been installed in Australia at AMMTEC Limited?s lab in Perth. A fifth SAGDesign test mill for radioactive ores has been built by Starkey & Associates, specifically for testing uranium ores and can be moved to any licensed lab in the world on a project basis.

Jan 1, 2014

By Chanki Jeong, Heechan Cho

In this study, batch flotation experiments were conducted to recover rare earth elements (REE) from an REE ore deposit in the Mushgai Khudag area, Mongolia. Apatite was found to be the major REE mineral while monazite and xenomite were observed as minor minerals. The main purpose was to float apatite to increase the REE content. Oleic acid was used as collector and MIBC was used as frother. Sodium silicate was used as a depressant for iron compounds. NaOH was used to adjust the pH of the flotation to about 9.5~10.0. The particle size was 90% less than 152 ?m (- 100 mesh). The content of REE elements was analysed by ICP - OES to determine the contents of REE such as Ce, La, Nd, Pr and Y. When sodium silicate was used, the best result was obtained using 0.2 mL of sodium silicate, 2 mL of oleic acid and 2 mL of MIBC. Under these conditions, the recovery of REE was about 78% and the grade of the first froth product was 42,995 ppm Ce, 24,088 ppm La, 14,236 ppm Nd, 4,388 ppm Pr and 1,570 ppm Y. When conducting flotation after iron minerals were removed by magnetic separation, a better result was obtained; with 2 mL of oleic acid, 2 mL of MIBC and no sodium silicate, the recovery was increased to 90% and the grade was also increased to 58,600 ppm Ce, 28,624 ppm La, 17,160 ppm Nd, 5,348 ppm Pr and 1,971 ppm Y.

Jan 1, 2014

By Mariana Peixoto

Muitos componentes de ferro fundido ficam expostos a altas temperaturas quando em serviço, podendo ocorrer a decomposição da perlita através da difusão do carbono da cementita para as lamelas de grafita, resultando em alteração microestrutural e degradação das propriedades mecânicas. A influência que a temperatura e o tempo de exposição têm sobre a microestrutura de um ferro fundido cinzento foi avaliado em amostras de quatro ferros fundidos de mesma base, com diferentes percentuais de cromo e molibdênio. Ensaios de banho de sal a uma temperatura de 500ºC foram realizados em corpos de prova com diâmetro de 10 mm. Os ensaios foram realizados com tempos de exposição a esta temperatura, após homogeneização térmica do material, de 0, 1, 2 e 4 horas. As análises metalográficas evidenciam a ocorrência da decomposição da perlita. Adicionalmente foram realizados ensaios de microdureza, a qual se mostrou sensível às alterações microestruturais geradas pela temperatura elevada. O ferro fundido com maior percentual de cromo e molibdênio apresentou melhor estabilidade da microestrutura para as condições ensaiadas.

Aug 17, 2017

By Fu-Shen Zhang, Mengjun Chen, Jianxin Zhu

"A novel approach for foam glass preparation, namely vacuum-aided powder sintering technique, was preliminarily investigated in the present communication. The key point of which was to prepare foam glass at a negative pressure. Compared to normal powder sintering process, the new approach could benefit the foaming process by shorting the holding time, reducing the amount of foaming agent and especially decreasing relative density of the product. Optimum conditions were 750 °C, 1000 Pa, 5 min and 1 wt.% foaming agent, respectively.IntroductionFoam glass represents a highly valuable solution for thermal and acoustic insulation, since it possesses a generally higher mechanical, chemical and thermal stability than other foams'1'. The first industrial processing for foam glass production, the direct introduction of gases (""blowing"") into the special molten glass, can be dated back to the end of 1930s'2'. At present, almost all foam glasses is prepared by powder sintering technique instead of blowing,3 since it reduces the temperature by several hundred degrees. Moreover, as fine glass powders or similar powders can be used to substitute corresponding glasses by this technique, considerable attention has been focused on the production of foam glass by considering fully recycled glasses, coal fly ash, or other solid wastes as raw materials,4 especially CRT glasses'3' 5', on the point of environmental protection.In a previous report'6', when discussing the lead removal and recovery from CRT funnel glass by a pyrovacuum process, we found that foam glass could be prepared at a negative pressure. Therefore, in this communication, the similarities and differences between the powder sintering process for foam glass at normal and negative pressure was preliminarily discussed."

Jan 1, 2011