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By Fábio Luiz dos Santos

As ligas de alumínio, em particular, apresentam certas restrições quando submetidas ao processo de união por soldagem. Isto se deve, principalmente, por apresentarem elevada condutividade térmica, elevada contração na solidificação e elevada solubilidade de hidrogênio. Levando em conta estes aspectos, o processo de soldagem FSW apresenta grande potencial para esta aplicação, visto que, é autógena, realizada sem fusão do material e sem utilização de escórias ou gases de proteção. A partir deste conceito, o objetivo do presente trabalho é avaliar a união de chapas finas de alumínio da liga 3105 H26, com espessura de 0,7mm. Para realização dos testes, foram analisados fatores como: penetração da ferramenta nas chapas processadas, ângulo de ataque, tipo de ferramenta e modo de controle de penetração (posição ou força). Os resultados indicaram que o modo de controle por força se mostrou o mais indicado para chapas finas, e que o regime transiente no início de soldagem foi a parte mais crítica para controle da qualidade da junta soldada.

Aug 16, 2017

By W. Zhu

ABSTRACT: This paper presents further developments of the principle of Construction Process Mechanics of rockmasses, The principle of loading variations analyses in space-time is systematically described. To demonstrate the applicability of the theory and method, the effect of the construction process of two practical engineering cases are analysed. ZUSAMMENFASSUNG: Das Mechaniksprinzip vom Konstruktionsprozess des Massenfels wird in diesem Aufsatz weiter Entwickelt.. Das Prinzip von Variationsladungsanalyse mit dem Zeit-Raumseffekt wird systematisch erklaert. Um die Anwendungsmoeglichkeit der Theorie und der Methode zu anschaulich darstellen, das Mechanikseffekt des Konstruktionsprozess wird fuer zwei praktische Anwendungsbeispielen zergliedert. : RESUME: Dans ce papier le development se fait pour principles de la mechanique de process de construction . Le principle de variable analyse considerant effet de temps et de Space est present ´e . Pour demonstrer l´appilicabilite de le theorie et la methode , l´èffect de processe de construction pour ce deax examples sont analysés .

Jan 1, 2003

By D. McSwain-Santos

Soda ash is the trade name for sodium carbonate, a chemical refined from the mineral trona or naturally occurring sodium carbonate-bearing brines (both referred to as natural soda ash) or manufactured from one of several chemical processes (referred to as synthetic soda ash). It is an essential raw material in glass, chemicals, detergents and other important industrial products. Production U.S. soda ash production during 2004 increased to10.9 million Mt (12 million st). Five companies comprised the domestic soda ash industry. Four were in Wyoming operating five plants. One was in California with one plant.

Jan 1, 2005

By P. Strand

Talk Outline ? Location and Regional Geology ? Two Unique Kimberlite Sources ? Mineral Chemistry ? Petrography, Age Dates ? Geophysics ? Exploration and Challenges ? Dyke versus Pipe dispersions ? Geophysics ? Prospecting ? Diamond Results ? Summary & Conclusions

May 1, 2008

By Sidney Katell

This; report, covering the period January 1965 through December 1965, is a continuation of a series that began with the publication of Information Circular 7516 in October 1949. It is the seventh in a series of reports prepared in cooperation with the American Association of Cost Engineers. The abstracted articles are concerned with all phases of cost engineering in the field of chemical and petroleum plants and related subjects. They are from the following sources: 1. American Association of Cost Engineers Bulletin. 2. Bureau of Mines Information Circulars. 3. Bureau of Mines Reports of Investigations. 4. Chemical Engineering. 5. Chemical Engineering Progress. 6. Chemical Week. 7. Coal Age. 8. Coal.3 9. Cost Engineering. 10. Hydrocarbon Processing and Petroleum Refiner. 11. Industrial and Engineering Chemistry. 12. Nucleonics. 13. Oil and Gas Journal. 14. Petroleum Management. 15. World Oil.

Jan 1, 1966

By A. Grimod

Rockfall drapery systems are commonly used as a simple, fast and cheap measure against the rock falling trajectories affecting very steep slopes. The system basically consists of a steel mesh, which is held on the top edge with a longitudinal cable fixed by means of a suitable number of anchors. The effect of this kind of intervention is to control the falls of the rocks, which are driven toward the bottom with slow velocity, or are stabilized on place. It can be used on any kind of slope to protect sensitive target in the mining industry, roads and railways, and inhabited areas. The falling blocks, typically smaller than 0.6 - 1.0 m in diameter, pile up into a trench (or into a ?pocket of mesh?) at the bottom. In comparison to other types of rockfall interventions, the simple drapery is cheaper, and its maintenance is easier, but on the other hand it cannot be considered the remedy for shallow instabilities, because it can only mitigate the effect of the falling trajectories. The design of simple draperies requires the analysis of several factors like the slope features (height, gradient, morphology), the geological and dynamic features (nature of the ground or rock, type of instability, erosion problem, blocks size), the environmental condition (presence of vegetation, aesthetical problem), the installation problem (accesses to the slope, safety for the workers, safety for the surrounding areas) and finally the performance required (temporary or permanent intervention, required maintenance, cost). Finally the most problematic design-step is the choice of the suitable mesh, the top longitudinal cable, and the top anchors type. Because of the highly variable nature of rockfall behaviour these structures cannot be standardized, but they have to be analyzed and designed for each case. Maccaferri has developed a new software application (MacRO 2) has a practical tool to define the mesh and the related supporting structure composed by up-slope cable and anchors. The software, based on the approach proposed by Muhunthan B. et al. (2005), allows designers to verify the top longitudinal cable, the anchors, and the mesh drapery, and to plan for maintenance procedures. Even if the method seems quite simple and rough, it is effective and lets the designer correctly foresee the materials and the geometrical features to be used on the interventions. This paper analyses the condition for the simple drapery installation, the main steps for the calculations, and it will present a case study in a U.S. mine. Nevertheless, even if the software allows a quick and simple calculation approach, onsite observations are always recommended in order to achieve a good design, with the ultimate goal of protecting property and human lives.

Aug 1, 2013

This three-part report provides the results of an industrial engineering study that assessed the safety and efficiency of underground ore handling in U.S. metal mines. One of the primary findings of the study was the improvement needed in controlling muck size in the are handling stream. Oversize ore is causing much additional labor, creating work stoppages, and is a principal cause of accidents in metal mines. The specific objectives of the Present Systems Study were to determine and evaluate the productivity of existing ore handling systems in a representative group of underground metal mines, to relate the available historical accident record statistics of these selected mines to the specific operations in the overall ore handling operations, and to highlight the potential areas of improvement for each mine on the basis of productivity and associated hazardous index for each operation.

Jan 1, 1974

By B. K. Loveday

The South African Institute of Mining and Metallurgy hosted a School on 'The Practical Design of Comminution Processes' at Megawatt Park (near Johannesburg) on 14th to 16th May, 1991 Derek Barratt, a Senior Consultant of Wright Engineers, Canada, and the main speaker, provided a good insight into how Wright Engineers design milling circuits, particularly large semi-autogenous mills. He was ably assisted by Jens Lichterof Allis Mineral Systems, who described some interesting examples of pilot-plant testwork and summarized South African milling practice. Mike Moys of the Witwatersrand University spoke on the influence of pulp viscosity on mill performance, and Johan Engelbrecht and Jeremy Bosman of Multotech

Jan 1, 1991

By D. W. Blaylock

1. The Lower Freeport and Lower Kittanning beds are the most important beds in Clearfield County, Pa., from the standpoint of production. The Lower Kittanning bed has the largest remaining recoverable reserves of any of the beds in the county. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 short tons per acre-foot of coal in place, are estimated at 1,909 million short tons as of January 1, 1953. Of this total, 1,177 million short tons is in beds 28 inches and more thick. Areas in some beds were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1955

By Sidney Katell

This report, covering the period January 1965 through December 1965, is a continuation of a series that began with the publication of Information Circular 7516 in October 1949. It is the seventh in a series of reports prepared in cooperation with the American Association of Cost Engineers. The abstracted articles are concerned with all phases of cost engineering in the field of chemical and petroleum plants and related subjects. They are From the following sources:

Jan 1, 1966

Project Details ? Located 420 km northeast of Yellowknife, Northwest Territories ? Jericho kimberlite discovered in 1995 ? Feasibility study showed +3,000,000 carats recovered from 2.6 million tonne reserve ? Nine year mine life ? Approx. 100 person workforce in full production ? First mine for Tahera, First new mine for Nunavut Completed Ambitious Construction Schedule During 2005 o Feb ? Mar/05 Winter road mobilization o Mar ? Dec/05 Pre-stripping, earthworks o Mar ? Apr/05 Camp facility, occupied May 3 o May ? Dec/05 Process plant o Jun ? Dec/05 Maint. shop, fuel storage, power plant o Jan ? Mar/06 Commissioning, start-up o April 2006* COMMERCIAL PRODUCTION

May 1, 2006

By Bahram Samani

The Bafq - Saghand ore belt (metallogenic zone) is the main region, where the major discovered Uranium resources are located. This belt is a unique Upper Precambrian terrane experienced Katanga ? Pan African tectono ? thermal events. The oldest sialic crust was formed during the middle Proterozoic and followed by K-granite intrusions of Lufilian Cycle (850-800 M.Y.).This event caused Tectono ? Magmatic ? Activization (T.M.A) characterized by intracontinental rifting and associated ore formations. This zone was considered as an iron ore belt in 1960s ? 1970s, and U ? Th ? REE belt in 1980s ? 1990s, but by new discovered of U ? Mo (Co, Au, As, Cu) mineralization is assigned as a U - Polymetal zone, hosting the full sequences of iron oxide (Cu, Au, U) ore forming groups. On the basis of detailed investigations this zone is characterized by the following peculiarities: This zone is the vestigial vessel of Gondwana basement, where the oldest granite and the first platform clastic cover is exposed. This zone is marginal part of Precambrian continental crust, consolidated in 1.3-1.0 B.a. The sub mature continental crust experienced Lufilian Orogenic and Katanga ? Pan African Tectono ? Thermal event by intercontinental rifting, and ore mineralizations. The ore forming stages were sequential processes, started by enriched mantle derived metallogeny, and ended by interaction of silanes/ HACONS (derived from outer core) with crust. The magnetite- apatite (REE, Ti) metallogeny developed from alkaline- ultrabasic magmatic differentiation, capable to from Au- Ni- Sulfide intrusive massifs during 850- 800 Ma. Degassing of silanes/HACONS from deeper level, not only caused mantle enrichment, and plume upwelling as a frontal load, but also played the main role to develop regional Si (-Na-K-Mg-Ca-Co3) metasomatism, and formation of U- Th- Ti- REE- (apatite, magnetite) deposits. The latest (583-510 Ma old) felsic magmatism was major IGU from U-Mo (-Co-As-Au-?Cu?) hydrothermal vein- type deposits. The albitite- type U- Ti- REE (Th) mineralization could be formed by interaction of ascending, and descending solutions along the deep- rooted structural conduits.

May 1, 2007

The original work statement of this contract was entitles: 'A Accident Analysis Model for Use in Underground Coal Mines.' The contract was scheduled for a duration of 26 months and was to be in three phases: Phase I - Model Development, Phase II - Application of the Model, and Phase III - Installation, Monitoring and Evaluation of the Model. Alter three months in Phase I, it became apparent that much of the needed data for the model was nut available and could not be made available within the original study schedule. Proceeding as plumed would have resulted in a model of limited utility. Personnel from Theodore Barry and Associates and the Bureau discussed the problem in detail and mutually decided to utilize the majority of remaining funds to assist the Bureau in solving these data problems and develop a stronger ongoing capability for safety analysis within the Bureau. Both tie contractor and the bureau officials involved believed that this decision greatly enhanced the Bureau's ability to develop future accident prediction models, whose rigor would greatly exceed what was currently possible.

Jan 1, 1972

By C. A. F. Sweet

The inter-relationship between these parties and the effect on the outcome of the project is often grossly underestimated. There are numerous success stories where the parties have worked as complementary teams aiming at the best outcome for the client company and achieving significant success. While there are a good number of occurrences where either the roles of the parties were unclear or perceived to be different from what others in the team believed or required them to be and the results were less than desired. This usually resulted in ongoing conflict, incorrect focus, working to different agendas and the result being a less than optimum result to Client Company. Mining, by its very nature of exploring where you cannot see, be it a shaft being sunk, tunnel being developed or other excavation that needs to be made, requires a very special working relationship between the parties. To understand this, and it applies equally well to mine and plant construction and other multiple function projects, one needs to start by describing the relationship of the parties. Often people believe that because they manage ongoing complex operations and large numbers of people that they can manage projects and as such the participants will ?fall into line.? At the outset it needs to be stressed that ?Project Management? is a specific type of management and needs to be understood as such. There are enough Colleges and Universities that teach project management, not only as a subject but also as a Master Degree. As you start up your project the relationship you establish between the client, project team (C.P.T) and the Engineering, Procurement, Construction and Management team (EPCM) will largely determine how successful your project will be. It is essential that from the outset a spirit of co-operation, support and respect be nurtured, and that it be actively carried through the project life cycle. There are several methods to facilitate this including team building exercises right at the start. This time and money will be well spent and recouped many times over during the project life cycle.

Jan 1, 2005

By A. J. Jager, D. P. Roberts

The stoping of platinum orebodies in the Bushveld has in the past been accomplished by using in-stope pillars to ensure stability of the workings. In the future, the use of continuous mining machines to mine the platinum orebodies is probable. It is not envisaged that such machines will cut in-stope pillars. This paper describes the alternative support systems that will replace the pillars and the stope geometries that will be required for this type of mining. The paper describes how the support resistance provided by in-stope pillars in current mining was determined and then evaluates support systems that can substitute for these pillars. Conceptual layouts based on existing breast mining layouts are presented. The layouts consist of panels of up to 100 m face length between rigid strike stabilizing pillars. A number of design charts are then proposed that allow for the design of appropriate support systems.

Jan 1, 2004

By R. L. Virta

Six companies mined fire clay in Missouri and Ohio during 2004. Production, based on a preliminary survey of the fire clay industry, was estimated to be 398 kt(438,700 st), valued at $9.81 million. This was slightly less than the production and value figures from 2003. Missouri was the leading producer state. It accounted for more than 70 percent of the U.S. production. Consumption Domestic producers sold or used fire clay primarily for refractory applications. This application accounted for 79 percent of the market. Refractory products made using fire clay include firebrick and block, grogs, high-alumina brick and specialties, refractory mortars and mixes, and saggers.

Jan 1, 2005

By S. G. Hardcastle, C. K. Kocsis

In Canada’s metal mines, ventilation, which requires electricity to operate the fans and fossil fuel for heating, accounts for a significant portion of the overall mine’s underground power consumption. Mine ventilation systems are usually designed near the end of the mine design process and often designed for the ‘worst-case-scenario’ with respect to ventilation demand. In Canada’s metal mines this is commonly dictated by either diesel equipment usage or heat management considerations. Once designed, mine ventilation systems tend to operate at this peak level throughout the operating life of the mine. This is despite there being significant periods when this quantity is not required this is done mainly due to lack of appropriate ventilation controls. Consequently, such systems are inefficient and wasteful and this must be changed if mining operations are to remain competitive while meeting increasingly more stringent regulations of underground environmental conditions. The advances in computing power and modelling software now make it possible to design, model and schedule a mine from opening to closure. The tools used for this include several disparate types of software. A developing trend is to design and plan the mine using orebody modelling software, followed by using discrete event simulation to predict production and evaluate various operating scenarios. It seems that again ventilation design is not being integrated into this process. Although, several modelling packages exist for ventilation design, little work has been done on integrating ventilation modelling into the overall life cycle plan of the mine. This paper will present a discussion of the work where the authors are attempting to integrate discrete event simulation for mine planning with ventilation modelling to predict the ventilation requirements for the operating life of the mine.

Jan 1, 2003

By A. Fahimifar, H. Soroush

Abstract: Triaxial tests were conducted on the schist specimens with various anisotropic angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strains, were measured and plotted for various conditions. The results obtained reveal the effects of schistose on the strength and deformability of the rock very clearly. Peak strength of the specimens for 00 and 900 schistose orientations are nearly the same. Modulus of elasticity of this rock varies with anisotropic angle. For 0 orientation modulus of elasticity increases to a maximum. Confining pressure increases the peak strength and improves the rock deformability. However, this effect is not the same for various orientations, and there are no similar trends for each anisotropy direction. Analysis of the results shows that consideration of a linear failure criterion such as Mohr-Coulomb is appropriate for the prediction of rock behaviour up to 10 MPa, rather than a non-linear one. The analysis also reveals that the friction angle and cohesion are affected by the anisotropy orientation, and this effect is more important for the cohesion than the friction angles. Resume: Les esseys triaxiales sur les echantillon d un roch schist avec les differents angles non-isotrop sous les tension lateral zero et sept et qoinze mega pascal (mpa) est fait et les covtraite et allongment unitaire sont mesure et leur curues est destine sous different condition les resultats obtenues montre les effets du schistosite sur le resistance et le ductilite vissiblement. Le resistance final sur les echantilions pour les angles o degre et 90 degree est equivalent. Le modoule d elasticite de ce roch sera difere par a port de l angle de stratification. Pour l angle o degree le valeur de modoule est le maximum. le pousse lateral augmenterai le resitance final, et sera amilterai le toleran le de ductilite. Mais cette effet bn est pas unigue pour les different stratification, et pour les diferents directions no– isotrop it n y a pas le meme solution. L analyse des resulitats montre que le criterre de ruin comme mohr–colomb est moderate pour le pousse lateral jusq av lo mega pascal , et ce n est pas neccesaire d utiliser de criterre no–linear . Cette analyse aussi montre que l angle de frottement et cohsion est en relation de la direction no–isotrop, et cette effet est olus important pour le cohsion par a port de l angle de frottement . Abriß : Dreiachsige Prüfung wurde auf den schist Exemplaren mit verschiedenen anisotropic Winkeln unter Bestätigen von Drücken von 0.7 und 15 MPa geleitet, und axiale Spannung axiale Spannungen, wurden gemessen und für verschiedene Bedingungen wurde geplant. Die Ergebnisse haben die Wirkungen von schisocity auf der Kraft und dem deformability des Felsen sehr deutlich erhalten offenbart. Maximale Kraft der Exemplare für 0° und 90 sind° schistos Orientierungen beinahe das gleiche. Modulus der Elastizität von diesem Felsen ändert sich mit anisotropic Winkel. Für 0° vermehrt Orientierung modulus der Elastizität zu einem Maximum. Einschränkender Druck vermehrt die maximale Kraft und verbessert den Felsen deformability. Aber ist diese Wirkung nicht das gleiche für verschiedene Orientierungen, und es gibt keine ähnlichen Tendenzen für jede anisotropic Richtung. Analyse der Ergebnisse zeigt jener Überlegung Kriterium eines linearen Ausfalls wie zum Beispiel Mohr Coulomb passend für die Voraussage von Felsen Verhalten bis zu 10 MPa, anstatt eines nicht linear ist. Die Analyse offenbart auch, daß der Reibung Winkel und Bindekraft werden beeinflußt von der anisotropic Orientierung, und diese Wirkung wichtiger für die Bindekraft ist, als der Reibung Winkel

Jan 1, 2003

By John H. Weitz

Dolomite, heretofore regarded merely as a variety of commonplace limestone, has suddenly attained headline prominence, partly because of the increase in demand for dolomite refractories to line metallurgical furnaces now working at an unprecedented rate of activity, but chiefly because it has become an ore of the light-weight metal, magnesium, needed in vast quantities for the manufacture of war machines. A multitude of inquiries, chiefly from war agencies and prespective operators, for data not only on locations of dolomite deposits but on their size and quality, has made it necessary for the Bureau of Mines to assemble all information available on this important subject. From the Bureau's own records, published information, and correspondence, date on locutions, extent, thickness, accessibility, workability, and chemical composition of high-grade dolomite deposits throughout the United states were accumulated for presentation herein. The report includes about 1,000 tabulations of analyses and a map showing locations of the deposits. The uses of dolomite are discussed in Bureau of Mines Information Circular 7192, "Occurrences and Uses of Dolomite in the United-States," published in 1941. The cordial corporation of many State ecological surveys and various individuals who have contributed information is gratefully acknowledged.

Jan 1, 1942

By R. L. Virta

Four companies mined ball clay in four States during2004. They were H.C. Spinks Clay (owned by Franklin Minerals) Kentucky-Tennessee Clay (owned by Imerys),Old Hickory Clay and Unimin. Production was estimated to be 1.46 Mt (1.61 million st) valued at about $56.9 million, based on a preliminary survey of the ball clay industry. In 2003, production was 1.31 Mt (1.44 million st) valued at $56.2 million. Tennessee was the leading producer state with 61 percent of production. It was followed by Texas, Kentucky and Mississippi.

Jan 1, 2005