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By F. A. Hill

Coal mining in the State of Washington offers many interesting problems for the mining engineer, due to the varied physical conditions occurring in different fields, and often in the same mine. The different coal seams worked in the same mine commonly require different mining and transportation methods for economical operation. The coal measures have inclinations ranging from 5' to vertical, and in the same mine the dip of the coal may vary from 30' to 50 . In all fields, the seams are extensively faulted, folded, and sheared. The quality of the coal produced ranges from brown lignite to bituminous coking coal, the following being typical analyses: Very little of the coal contains as much as 0.75 per cent. sulfur. The brown lignites occur mostly in Lewis and Thurston Counties, and as a rule are very cheaply mined. This coal has been successfully used in locomotives of the Oregon & Washington Railroad, after equipping them with specially designed fireboxes. The sub-bituminous coals occur in all the coal-mining counties. Their cost of production varies widely, according to the character of the formations, the pitch, and the wall conditions. This makes a fairly good steam coal, but the lump is used mostly for domestic trade, after grading into lump, nut, and pea. The coking coal is used for making coke, and for locomotive and other boiler fuel. It yields a strong metallurgical coke, quite high in ash, though seldom exceeding 18 per cent. ash. Most of it is susceptible to

Jan 1, 1920

By E. M. - Technical Papers Spokes

A.B. Rushton The work and resulting publications of the Committee on Underground Coal Mine Safety and The President's Commission on Coal were appropriate at the time of publication. The statistics cited in the publications appeared to be valid, and the actions proposed by the committee had merit. Although the actions proposed to achieve further improvements in safety may have been worthy of repeating, to associate statistics (Table 1) that are seven to eight years old with company names is bad. Statistics are readily available from the Mine Safety and Health Administration (MSHA) and are usually within three months of being up to date. A review of the most recent Coal Controlling Co. Report will reveal significant changes in the rankings. The more recent statistics should have been cited, or at least compared with those used in the article. Westmoreland Coal Co. is listed as having a 21.1 disabling injury rate for the period (1/78-12/80). The disabling injury rate for the Company for the year ending 1985 was 7.4 for the underground mines and 6.25 for the total facilities. Through March 1986, the dis- abling rate for the underground mines was 2.86. The management and employees of Westmoreland Coal Co. are committed to safety. The improvements achieved over the past five years attest to that commitment. We are justifiably proud of the achievement and dislike being misrepresented as in the April 1986 article Reply by E.M. Spokes I regret that the lapse of time since the original work gives a picture of safety practice that is no longer true today. That Westmoreland has reduced its disabling injury rate by 65% to 7.4 in 1985 is most commendable, and I congratulate you for this accomplishment. It is typical of the progress sought by the National Academy of Science and National Research Council when they funded the original study and published "Toward Safer Underground Coal Mines" in 1982. If a significant number of companies do as well as Westmoreland, the report will have served its purpose. Since the paper was primarily a condensation of the original report, it would not have been appropriate to seek access to later statistics. The purpose in seeking its publication at the time of presentation was to reach those who might have missed the original report. The fact that publication was delayed has not voided that purpose and may have reminded some who were aware of the original that its recommendations still apply to improvement of underground coal mine safety

Jan 1, 1987

And a new generation of safety culture experts are telling mining companies how to use it: It is a situation that is still too common in the mining industry: the latest personal protective gear is in place. The safety rules are known and followed. And then, in a moment of inattention or carelessness, a mistake is made and someone gets hurt or killed. Common wisdom claims that such accidents are impossible to eliminate entirely. Mining is dangerous, and some miners will always be hurt and killed. An increasing number of mine safety experts, however, reject the common wisdom. A year with zero mining deaths is possible, they say; with the use of one of the newest weapons to the mining industry in the safety war: the concept of safety culture. Safety culture refers to the set of attitudes, beliefs, perceptions and values that influence safety in the work environment. It is also sometimes called the way an organization behaves when no one is watching. Robert Peters, of the Office of Mine Safety and Health Research (OMSHR) at the National Institute for Occupational Safety and Health (NIOSH), describes safety culture this way: ?It?s what?s believed on a day-to-day basis. For example, if a miner sees a workplace hazard and he truly believes that his boss wants him to identify the hazard and bring it to the company?s attention, that would be an example of a positive safety culture.?

Jun 1, 2010

By G. A. Young

THE Geological Survey was created in 1842 to aid the development of Canada's mineral resources. Although the institution has been in existence for nearly 100 years and has accomplished an immense amount of work, the need for its services remains as great as ever and, indeed, it is difficult to imagine a time when the country will no longer require a Geological Survey. This is so because of the tremendous effort required to make an adequate geological examination of so large an area as is embraced by Canada and partly because what today may seem an adequate geological examination proves, later on, to be inadequate. The ultimate objective of the Geological Survey is to complete the study of all phases of the geology of Canada, that is, to determine how and when the physical features originated, how and when the soils and other unconsolidated deposits were formed, and how and when the solid rocks and associated deposits were produced and assumed their present conditions. When the study has been completed, any only then, will it be possible to make a reliable estimate of the country's mineral resources. This appraisal embraces more than determining the value of already discovered deposits: it also involves attempting to establish what kinds of undiscovered deposits may be present and where they may occur. The estimating of the potential mineral wealth can be clone only after the geology of the country is known. Not until then will it be possible to forecast what types of valued deposits may occur in a district and what types will almost certainly be lacking. A thorough knowledge of the geology of the country is desirable not only to permit estimating the potential mineral resources but also as an aid in locating and developing mineral deposits whether these are of the nature of a bed of limestone, a seam of coal, a reservoir of petroleum, a vein, an irregular body of sulphides, or any other type of deposit.

Jan 1, 1940

By Ernest Stütz

(New York Meeting, October, 1918.) THE problem of increasing blast: furnace efficiency through diminution of flue-dust production while operating with burdens consisting largely of fine ores has of recent years attracted the attention of metallurgists, whether directly or indirectly interested in the economies of iron smelting, and the various methods evolved from theory or practice have been submitted to wide discussion. After the very thorough and, at that time, exhaustive view of the whole subject, which was afforded to the industry by the meeting of this Institute in February, 1912, the subject was again taken up at the meeting of the Verein deutscher Eisenhüttenleute at Diisseldorf in December, 1912. While American and German conditions are not entirely identical, it may be of interest to give here the words of the gentleman summing up the discussion at the Diisseldorf meeting: ' The chief advantage offered by the use of briquettes lies in the fact that disturbances in the furnace, caused mostly by the presence of fine ores in the burden, are avoided, and that blast pressure can be considerably reduced. The resulting economies cannot be overrated, as, with lower blast consumption per ton of product, the installation will be able to take care of increased production. In consequence of lower pressure and speed of blast, heat is more efficiently utilized, flue gas temperature is lowered, and coke particles are less liable to be carried along with the flue dust, of which considerably less is produced. Finally, by increased regularity of operation and higher . temperature in the lower parts of the furnace, the quality of the product is improved. The question of briquetting iron ores has grown to be one of the most important in the iron industry, and, it is not any more a question of what is the cost of briquetting ton of ore, but what, in using ore briquettes, is the cost of production of a ton of iron.'

Jan 7, 1913

By Yves Dardel

THE literature concerning the remelting of aluminum and its alloys is very rich. Unfortunately the greater part of the papers about this subject have no scientific value, for the theories or explanations are too often in opposition to the laws of physical chemistry. Furthermore only a few of the methods of purification1,2 are considered in the literature. Hence it has seemed necessary to the author to sketch a general theory of the purification of secondary aluminum. The purpose of the purification is to eliminate the impurities that the charges and the atmosphere of the furnaces bring into the bath during the successive remeltings. Indeed scrap as well as metal can be used when soiled with oil, greases, water, .. , if it has been sufficiently dried and contains oxides. At the melting point of the metal, the oils and greases are decomposed into their constituent elements H2, 02, H2O, C02, CO, CH4, and others. These gases are added to the corresponding gases in the atmosphere of the furnace. The impurities introduced into the metal during the remelting will accordingly be the products resulting from the action of these gases on the liquid bath. The quantity of hydrogen that is soluble in aluminum and its alloys is given by the relation of Sieverts3 as a function of its partial pressure PH2 in the atmosphere [m = K _%/PH, [I]] where K is a constant, which depends only upon the temperature and increases with it. The experiments of Röntgen and Braun4, Röntgen and Möller5, Bircumshaw6 and Winterhager7 have rendered it possible to determine the value of K, when the temperature is inferior to 1.000°K. One obtains: [log K = - 4,702.5 + 0.238 [2]] Besides its usual signification, the term PH2 represents also the internal pressure of dissolved hydrogen, since in the equilibrium, that is, when no gas exchange occurs between the two phases, the pressures of hydrogen in the metal and in the atmosphere must be equal. Eq I shows that when the partial pressure of H2 increases the amount of dissolved hydrogen in equilibrium increases, and that, if the contrary occurs, the quantity of H2 should diminish. However, if for any reason the diffusion of hydrogen is hindered and the total amount of dissolved gas remains constant while the temperature lowers, the internal pressure of H2 increases until it reaches the value of the hydrostatic pressure. At this point, bubbles of hydrogen appear in the bath and escape out of it. The amount of hydrogen in the metal is then limited by a maximum depending on the hydrostatic pressure, which is practically equal to one atmosphere. Indeed hydrogen does not accumulate in the form of a hydride appearing as a separate solid phase. However, even the mechanism of the solubility is not yet elucidated. One does not know exactly as yet, whether the

Jan 1, 1947

By Max Gwynn, Tony Suckling

"The new Wembley Stadium is the most spectacular soccer stadium in the world, built to the highest specifications, using the latest technology and offering visitors an unrivalled match-day experience. Wembley Stadium is the home of English soccer, dating back to 1918 when the British Government began planning a British Empire Exhibition with a stadium as its centrepiece. The Empire Stadium, as it was originally known, was completed in 1924 in just 300 days and cost £750,000 ($1.4m). It was finally closed in 2000.The new Wembley Stadium, which opened in 2006, features fully covered seats for 90,000 fans and a striking arch that sits above the northern half of the stadium. With a span of 315 m (1040 ft), the 133-m (440-ft) tall arch is the longest single-span roof structure in the world. It supports the entire weight of the northern roof and 60% of the weight of the southern retractable roof. This means there is no need for columns within the stadium and ensures unobstructed views.Multiplex Constructions (UK) Ltd. employed Stent Foundations Limited to construct the £10m ($19m) foundations package for the new stadium. The scope of works for the foundation package included the design and construction of all foundations, including all main works piling, temporary works piles for the arch and roof, and tower crane piles. The scope also included trial piling and pile testing, setting out and removal of spoil.Piles were constructed by using bored cast-in-place techniques with both hydraulic and traditional crane-mounted rigs. Stent also installed sheet-piled walls at three locations to the site’s northern boundary. In addition to the main contract works, Stent constructed a £2m ($3.8m) contiguous bored-pile retaining wall within the demolition and earthworks package (Figure 1). This work was carried out as a subcontractor to Griffith McGee."

Jan 1, 2008

By C. J. Myers, D. L. McKinnon, A. A. Dasys

In 1988, the National Institute of Occupational Health and Safety (NIOSH) published an information bulletin stating that whole diesel exhaust should be considered a probable carcinogen. Since then, regulations across Canada and the United States (Mine Safety and Health Administration, MSHA) have looked at appropriate exposure limits for underground mine workers. In Canada, an interim standard of 1.5 mg/m3 Respirable Combustible Dust (RCD) has been adopted by some provinces and is being looked at by others. MSHA is considering levels as low as 0.5 mg/m3 soot. Golden Giant, being aware of regulatory developments, decided to look at means of reducing diesel particulate on thier large production machinery. This machinery (LHDs and haulage trucks) is powered by Detroit Diesel 71N Series engines and is used to produce 3000 tonnes of ore/day with a longhole mining technique. Having looked at the various control technologies, it was decided to evaluate the potential of using diesel particulate filters with a copper-based fuel additive for regeneration (the process by which collected particulate is burned off). This paper outlines the control technology used and the results of the field evaluation indicating the benefits to the underground mine worker.

Jan 1, 1993

By Afranio Marcio Costa

No lingotamento contínuo a busca pelo aumento de produtividade tem sido realizada com sequências longas, ou seja, várias corridas e muitas vezes com aços de diferentes composições químicas. Isso resulta na geração de placas de mistura e vários trabalhos buscam entender este processo. Este estudo tem como objetivo validar o modelo matemático de mistura existe no lingotamento da Gerdau Ouro Branco para garantir a correta aplicação da região de mistura, visando atender às especificações dos produtos, norma ASTM A36. Os resultados encontrados nas placas amostradas confirmaram a eficiência do modelo para estimar a zona de mistura. Além disso, para garantir a aplicação dessas placas na norma estudada foi utilizado o modelo de previsibilidade de propriedades mecânicas existente na laminação de chapas grossas. Finalmente, os resultados reais de composição química, limite de escoamento e resistência encontrados nas chapas avaliadas confirmaram as previsões dos modelos e atenderam às especificações do aço.

Oct 30, 2017

By J. L. Gregg

RECENTLY there has been considerable interest in the production and use of, extra hard alloys composed primarily of tungsten and carbon. Dr. Hoyt's recent paper1 gives a good description of these alloys and describes their performance when used as tools. There are a number of these alloys on the market sold under various trade names, and it is the purpose of this paper to describe the results of an investigation of the structure of five of these alloys by means of microscopic and X-ray methods. The samples studied were in the form of small tools or wire-drawing dies, which were either purchased or supplied as samples. They were in some cases not supplied by the original makers but were furnished by the agents in this country, and we wish to call attention to the fact that they may not be truly representative of the materials supplied under the various trade names. No performance data are given and no inference as to the inferiority of one alloy as against any other is made K Schröter2 recently described methods for polishing alloys of this type for microscopic examination and has presented photomicrographs of several alloys. However, he did not identify their constituents or describe methods for their identification.

Jan 1, 1929

By J. J. Bezuidenhout

The waste-heat boiler is used within the Sulphide flash smelting process as the main dust and energy recovery unit. The large volume of off-gas discharged from the flash smelter is at a very high temperature (1350°C) and contains a significant dust load that subjects the downstream waste-heat boiler to tough and demanding conditions. The boiler cavity is especially prone to dust accretions, fouling, and corrosion caused by accumulation of molten particles and precipitation of sulphuric acid. Computational fluid dynamics (CFD) is applied within a qualitative study to model the flow and heat transfer distribution throughout the waste-heat boiler. The commercial CFD package, Fluent 6.2.16, was applied to a modified waste-heat boiler (23 m ×11 m ×5.4 m) within the Outokumpu flash smelting process. This investigation focuses on the geometric modifications to the typical boiler design, which includes elevation of the ceiling, placement of flow-obstructing baffles and radiation plates parallel within the flow path. Also investigated were various boiler operating conditions such as the circulation of process off-gas, air leakage from the dust discharging hoppers and variation in inlet gas composition. The geometric modifications had the desired effect of increasing the volumetric utilization and therefore enhancing heat transfer between the boiler surface and the gas stream and dust segregation. Introducing circulated off-gas at a rate of 20 m/s and at a 45° angle to the front of the waste boiler further enhanced cooling while reducing the high impact of the furnace-uptake gas-stream on the boiler ceiling. The placement of radiation plates was found to be very effective in enhancing the heat transfer surface and distributing gas flow within the boiler. These results present recommendations towards an improved waste-heat boiler design. Keywords: flash smelting, waste-heat boiler, CFD simulation, off-gas cooling.

Jan 1, 2008

By H. E. Stauss, J. Hino

INTEREST in silicon has arisen again in the past decade as a result of improvements in crystal rectifiers.' Although the preparation of silicon was first reported by Berzelius in 1880, the early product was of relatively low purity, and only the need for rectifiers in World War II led to the production of a 99.9+ pct pure powder. This material in crystalline form was consolidated into massive silicon for use, and the method developed was to melt it with selected added constituents as "doping" agents. Melting techniques, therefore, are of great importance. There are two basic problems in producing silicon ingots free of doping additions; one is the prevention of spitting and the other is prevention of cracking of the ingot during freezing. The most satisfactory arrangement yet developed for producing massive silicon is to melt and freeze in a cylindrical quartz crucible surrounded by a concentric heating element and concentric radiation shields or insulation. For example, use can be made of a tubular heater with a high frequency generator as the source of power and reflecting shields of alundum cylinders. The spitting of silicon is related to gas evolution, and the gas comes from two primary causes—adsorbed gas and the reaction products of silicon and the crucible. Gas is also released from bubbles contained in the quartz crucible walls. Improved removal of adsorbed gas can be achieved by means of controlled melting and freezing. The seriousness of the problem in vacuo is reduced with an electrically operated mechanical movement of the high frequency power coil. The upper portion of the powder charge is melted first and the high frequency coil lowered until the powder is completely molten. During cooling the high frequency coil is raised slowly. These means also reduce the final nonviolent extrusion of large beads of metal through the ingot top during freezing. Better control of spitting and bead extrusion is obtained when melting is done under helium at. atmospheric pressure instead of in vacuo. The problem of reaction between silicon charge and crucible in practice is confined to the reaction between silicon and quartz. This2 apparently is: Si + SiO2 + 2SiO The part that this reaction plays in spitting has not been isolated for separate study. SiO is a volatile vapor at the melting point; of silicon and is released freely during melting in vacuo, but hardly at all in helium at atmospheric pressure. The cracking of ingots is a major difficulty in melting silicon, and its prevention requires special melting techniques or the addition of "toughening" agents such as aluminum or beryllium.' The cracking of the ingots has been explained as being the result of the expansion that occurs upon freezing; although direct observation of freezing ingots reveals visible cracks on the surface only after a red heat has been reached, suggesting that cracking is the result of differential contraction of silicon and quartz. Silicon wets quartz, and the ingot adheres tightly to the crucible. Therefore as ingot and crucible cool, the two either have to pull apart, or at least one must crack. Surprisingly, in spite of the relative thinness of the quartz and the thickness of the ingot, the ingot and the crucible both crack. Microscopic and X-ray4 studies fail to show any plastic flow other than twinning in the ingots. Slow cooling fails to prevent cracking. Another possible solution to cracking is to weaken the crucible. Use of thin-walled crucibles finally led to success with fused quartz crucibles with a wall thickness of 0.25 to 0.50 mm. With such thin-walled fused quartz crucibles consistently uniform success is secured in producing sound ingots 30 mm in diam from the purest available grade of silicon (99.9+) without the use of any type of addition. Melts are made in the size range of 50 to 100 g. Omission of a deliberately added doping agent is not sufficient to insure pure ingots. The reaction of silicon with crucibles and the resultant solution of impurities in the silicon is well-established." In this laboratory, the presence of Al, Be, and Zr has been found spectroscopically in ingots melted in contact with alumina, beryllia, and zircon. The best crucible materials reported in the literature are MgO and SiO2. Use of MgO in this laboratory has resulted in a heavy deposit of magnesium on the furnace walls, showing that a reduction of the magnesia occurred and the resulting magnesium removed from the melt by volatilization. In the case of quartz, the silica is reduced and SiO liberated to deposit on the equipment walls. There probably is real danger that oxygen is dissolved in the ingot when either magnesia or silica is used as the crucible material. Preliminary analyses by Dean Walter in his vacuum unit in this laboratory6 indicate the presence of oxygen in undoped silicon melted in quartz.

Jan 1, 1953

By Gerard A. Flierman

INTRODUCTION There is a lot of discussion about the relative merits of sinter and pellets as components of a BF-burden. Many people claim that sinter is to be preferred and that the percentage of pellets in the burden must be restricted to 20%. During BF-trials in IJmuiden various amounts of pellets having various basicities were tried. It was concluded that there were no significant differences in furnace performance. Consequently the choice between sinter and pellets must be based on the local manufacturing costs (1). Table 1 gives a summary of the pellet experience in IJmuiden. [ ] Because the BF-trials were relatively short, a survey of published BF-operating data has been undertaken to investigate if differences between a sinter and pellet based BF- practice could be found. The comparison of BF-operating results has been restricted to coke rate and productivity.

Jan 1, 1977

By Chao Yang, Liguo Tian, Yan Yang

"The Jinfeng gold mine is one of the three gold mines that Eldorado Gold has in China and it is the second largest gold mine in China. The mine is located in a relatively remote and mountainous area in the southwestern Guizhou province. The orebody is similar to the Carlin type deposit in Nevada. The mill throughput was designed to treat 3,600 tones per day. The ore comes from open pit mining and underground mining, and is fed to one-stage jaw crushing. The crushed ore is stockpiled, reclaimed and then fed to the SABC grinding circuit. After classification with hydrocylones, the ore is floated, and the resultant concentrate is oxidized biologically in a process known as BIOX®. The oxidized concentrate is then washed in a CCD circuit and finally leached with cyanide in a CIL circuit for gold extraction. Jinfeng produces about 180,000 oz of gold per year.This paper introduces operations and modifications of SABC circuit over the past three years, and then describes some technical characteristic of the SAG mill and other circuits in the processing plant.Major modifications and improvements on the SABC circuit are described in the paper, including:1. Impacts of grinding ball and mill liner with respect to material selection, quality, hardness, manufacturing methods, and interactions between mill liner and grinding ball.2. Effect of milling operation parameters on milling efficiency.3. Impacts of SAG mill scats and modifications of grate size to improve mill throughput.4. Design and construction of a pebble crushing system, and recycle the crushed scats to the SAG mill to improve mill throughput.With the above-mentioned modifications, 20% increase over the design in mill throughput has been realized over the past three years, and operating cost has been significantly reduced. However, some issues still remain, and thus process modifications and technical innovations are still needed."

Jan 1, 2012

By M. L. Fuller

DURING the last several years many papers have appeared dealing with the structure of highly polished metal surfaces The awakening of interest in this subject is due to the applicability of the electron diffraction technique to the study of surfaces The original theory of Beilby1 considered the surface of polished metals as of the nature of a super-cooled liquid or a vitreous, amorphous solid The electron diffraction effects from polished metals have been interpreted by many to be a direct experimental proof of the correctness of the Beilby theory This interpretation has been strongly opposed by others, so that at the present time the subject is in an uncertain and controversial state In the present paper new, and hitherto unpublished, electron diffraction effects from polished zinc are described These observations indicate that the polished surface of zinc is crystalline PUBLISHED WORK Many papers2-10 have interpreted the electron diffraction evidence as proof of the Beilby amorphous theory All investigators agree that highly polished metals give rise to two diffuse diffraction haloes, similar to those obtained by the diffraction of X-rays in liquids and vitreous solids It is this similarity that leads to the amorphous-layer interpretation of polished metals Strangely, the interatomic distances calculated from these haloes are very similar for the various metals investigated, in spite of a rather wide range of such distances in the crystalline and liquid states The calculated atomic sizes are, furthermore, smaller than are experienced in the normal states of the metals In spite of these anomalies, the amorphous-layer interpretation has been adhered to by many One investigator, S Dobmski,11 differs from the others in his experimental results By polishing under benzene in order to avoid the possibility of oxidation, Dobinski obtains diffuse haloes of [radire] different from those previously obtained He thus obtains a more rational quantitative correlation of-the diffuse haloes with the amorphous-layer theory

Jan 1, 1938

By Stewart WJ

Australia's first offshsore well was spudded in on 27th December 1964 and resulted in the discovery of the Barracouta gas field. Further exploratory drilling led to the discovery of the Marlin gas field in December 1965, the Kingfish oil field in April 1967 and the Hblibut oil field in June. 1967. In September 1968, a small oil reservoir was found in a sand below the main Barracouta'gas reservoir. The Snapper gas field was discovered in May, 1968 Information on exploration activities associated with the discovery of oil and gas in the Bass Strait area may be found in the paper, "Exploration in the Gippsland, Bass and Otway Basins, Australia" by B. M. Hopkins. _ Development of the commercial fields is being undertaken on an equal participation basis by Hematite Petroleum Pty. Ltd. and Esso Exploration and Production Australia Inc. Esso Standard Oil (Australia) Ltd. is responsible for the design, construction and operation of the production facilities.

Jan 1, 1970

By Edward E. Johnson

The Bureau of 'Mines publishes in its ?Minerals Yearbook? a series of indexes on the domestic minerals industry. Among these are the index of physical volume of mineral production, indexes of stocks, and indexes of average unit mine value and implicit unit value, This report describes the material coverage of these indexes and the methods used in their construction. Detailed descriptions are given for several other mineral-oriented indexes regularly published by other government agencies. These descriptions give the index user a better understanding of what each index purports to measure and aids him in selecting the most appropriate index for his purpose.

Jan 1, 1965

By M. El Tokhi, H. Arman, B. M. Amin

"This paper aims to overview some mechanical and physical features of the gabbroic rocks. The study has two phases: filed study/in-situ measurements and laboratory work. During the field studies, rock block samples were collected from different locations of the study area to represent the different types of the gabbroic rocks. Either core or rock samples for various tests were prepared from rock samples taken to the laboratory. The unconfined compressive strength (UCS), indirect tensile strength (ITS), point load index (PLI), Schmidth hammer rebound value (SHV), slake durability index (SDI), sonic velocity (SV) and unit weight (UW) test were carried out either on the selected rock block samples or core samples.INTRODUCTIONThe geology of the United Arab Emirates (UAE) has been divided into three major rock units (Lippard et al., 1986); an autochthonous succession, allochthonous units composed mainly of Mesozoic rocks and include the Sumeini Group (concomittent slope sediments), Hawasina Complex (basinal sediments) and the Semail ophiolite nappe (massive slice of former oceanic crust), that were emplaced as a series of thrust nappe in the Late Cretaceous and Neo-autochthonous sequence of Maastrichtian and Lower Tertiary sediments.The Semail Ophiolite (600 km long and up to 150 km wide) is thought by some authors (Glennie et al., 1990) to have been generated along a subduction related back-arc spreading axis during the Cenomanian-Turonian and was obducted onto the Arabian continental margin during the Campanian. Others, however, consider it to represent a primitive arc-spreading center related to oblique subduction Lippard et al., 1986). The Ophiolitic rocks in the study area comprise mantle and crustal sequences. The mantle peridotite and crustal gabbros are the dominant rock types of the exposed Semail Ophiolite north of the Hatta zone. This paper is only concentrated on the gabbroic rocks."

Jan 1, 2015

By Manuel Candia

El presente texto señala la importancia del factor humano en la productividad de la industria peruana. Para ello, se evalúa las causas de los altos costos de producción y se busca aumentarla a través de conocer la función de cada empleado involucrado en el área de trabajo. Para ello, es necesario entender el significado de la palabra productividad y asi determinar la contribución del ingeniero a la productividad y de los empleados a su cargo. Asimismo se debe evaluar las condiciones donde se labora, la comunicación adecuada con el personal, la mejora de empleo de los recursos energéticos, la capacitación de los empleados, el diseño de la productividad a través de un programa participativo entre empleados y directivos, y finalmente el fortalecimiento entre las relaciones de la gerencia y el equipo administrativo.

Nov 20, 1978

By S. K. Kawatra

"A typical steelmaking facility produced 50,000 tons per year of slag in their hot-metal desulfurization process. This slag had a sufficiently high iron content that it could be beneficiated and recycled in a blast furnace, provided that the slag could be agglomerated into pellets suitable for use as blast furnace feed. In this work, beneficiated slag was agglomerated using both a conventional bentonite binder, and a fly-ash-based binder (FBB) that was formulated by the investigators. The FBB consisted of a combination of highcarbon fly ash with calcium hydroxide activator, allowing the FBB to exhibit binding properties when moistened. It was determined that beneficiated slag agglomerated with FBB had superior compressive strengths compared to slag agglomerated with conventional bentonite binder. The FBB is therefore a satisfactory method of binding the agglomerated slag. Since the fly-ash component of the FBB is commonly discarded as waste, this approach also provides a means for utilizing high-carbon fly-ashes that currently have very little commercial value.IntroductionIn 2006 approximately 72.4 million short tons of fly-ash were produce in the United States [1]. The majority of fly-ash which was used that year was consumed concrete, structural fills, and cement. It is also used in road base, aggregate, and other applications. However, 55.2% of the fly-ash produced in 2006 was not utilized and ended up being sent to a landfill. Essentially all of the land filled fly-ash could be a suitable binder for pelletizing desulfurization slag and other steel plant waste oxide materials. Fly-ash based binders (FBB) have been shown in laboratory studies to be suitable for producing iron ore concentrate pellets of equivalent strengths as those bonded with bentonite [2,3,4]. The utilization of highcarbon fly-ash within the market is important for reducing the volume of currently unmarketable and land filled fly-ashes. FBB would be a much cheaper alternative to the current bentonite binder or organic binders used for iron ore concentrate and would help to reduce pellet costs. Currently, transportation more than doubles the final cost of bentonite since it is produced hundreds of miles from the pelletizing plants, while fly-ash is produced from power plants located nearby pellet plants and steel mills. FBB’s also show promise for use in other high volume applications such as foundry sand mold binders."

Jan 1, 2008