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By Maria Anita de Paula Negreti

Neste trabalho, foram obtidos compósitos poliméricos de Óxido de Grafite (GO) incorporado em Poli(metaclilato de metila) (PMMA). A obtenção do Óxido de Grafite foi realizada pelo método de Hummers modificado. Em seguida foi ainda adicionada uma etapa secundária de tratamento térmico à 1000ºC no GO obtido a fim de expandir as lamelas de grafite e remover os grupos funcionais aderidos durante o ataque ácido do grafite. As cargas obtidas foram caracterizadas com o auxílio das técnicas de Difração de Raios-X (DRX), constatando a expansão das folhas após o tratamento térmico. O estudo comparativo dos compósitos de matriz polimérica com 3 % de concentração de GO antes e após o tratamento térmico foi realizado com o objetivo de entender a contribuição nas propriedades reológicas do polímero com a adição da carga de GO. Os resultados reológicos apresentaram um aumento da viscosidade complexa tanto no ensaio de Varredura de Tempo, quanto no Cisalhamento Oscilatório de Pequenas Amplitudes (COPA).

Aug 16, 2017

By M. Gous

Keywords: Pyrometallurgy, Namakwa Sands, ilmenite, DC arc furnace, titania slag, pig iron Namakwa Sands is a heavy minerals mining and beneficiation business in the Anglo Base Metals Division, and operates along the West Coast of South Africa. The business encompasses mining, mineral concentration, separation, and smelting operations. The smelting process comprises the carbonaceous reduction of ilmenite to produce titania slag with a TiO2 content of 86%, and iron with a carbon content of 2.5%. The Namakwa Sands smelter, situated near the Saldanha Bay harbour, commenced smelting operations in 1994, when a 25 MW DC arc furnace was commissioned. The smelting operations were expanded in 1999, with the commissioning of a second 35 MW DC arc furnace. Despite the fact that ilmenite smelting poses a technical challenge in terms of the high temperatures required, the physical characteristics of the slag, the constraints placed on the feedstock, and the tight product specifications, Namakwa Sands has continually increased slag production since 1995. High furnace feed-on utilisation and furnace stability, complemented by continuous improvement drives, will be the vehicle to drive performance in the short term, with longer-term performance enhancements due to strategic process development.

Jan 1, 2006

By Francis Chachula, Niel Erasmus

"In 2002, Titanium Corporation Inc. focused its attention on the development of a process for the recovery of valuable heavy minerals, including zircon and titanium bearing minerals from oil sands froth treatment tailings. The development of a process flowsheet to recover the titanium and zircon minerals from the Athabasca oil sand tailings has evolved through many laboratory, bench and pilot scale iterations.Initial development work focused on so-called ‘beach sand’ material, which is tailings material deposited over a period of time close to the tailings pipe discharge. The derived process flowsheet primarily consisted of gravity concentration stages, which is typical of all mineral sands operations. Titanium Corporation’s business plan calls for the utilization of tailings directly from the tailings pipeline – the process developed around the beach material is therefore risky as it differs from the live tailings in a number of aspects, with the effects on the process unknown. Titanium Corporation successfully obtained an intermediate product through a ‘bulk sampling plant’ coupled directly to an Oil Sands operator’s froth treatment tailings pipeline, during the summer of 2005. Subsequent further processing of this material resulted in poor separation or concentration of the heavy minerals due to a number of reasons. A more effective process flowsheet had to be developed.The newly derived process is basically a marriage between mineral sands technology and oil sands technology that can economically concentrate and recover the heavy minerals and entails the incorporation of a flotation process that takes advantage of the entrained bitumen in the feed to separate the heavy mineral fraction from the quartz gangue This paper will describe the newly derived process as well as the successful results of a subsequent on-site concentrator pilot campaign completed during the 3rd Quarter of 2006."

Jan 1, 2008

Determine the advantages and operational limitations of water-let-assisted cutting used with mining equipment. Approach The Bureau of Mines con-ducted a research study to evaluate water-Jet-assisted cutting both in the laboratory and in underground mines. Earlier research on water-jet-assist was limited to laboratory studies where bit speeds and penetration depths were very low and large cutting force reductions were reported. For the past years, research by the Bureau of Mines and others has been concerned with the application of water-jet-assisted cutting under more realistic mining conditions. Study Results Water-jet-assisted cutting employs a mechanical cut-ting bit combined with a moderate to high-pressure water jet directed just in front of the bit tip to assist in the cutting process. Recent Bureau findings show that the addition of the water jet to the cutting bit can improve cutting in harder materials, significantly reduce respirable dust and bit wear, and increase product size. Some of these findings are presented as follows.

Jan 1, 1987

By D Pastars, J L. Mauk

Located at the southern end of the Awhitu Peninsula, the Waikato North Head ironsand mine is approximately 50 km southwest of Auckland . The ironsand deposit consists of Quaternary sands, clays and peats, formed by aeolian and marine processes. We sampled on widely- and closely-spaced intervals to test variability within the mining area. X-Ray powder diffraction shows that samples contain feldspars, quartz, pyroxenes, amphiboles, clays and titanomagnetite. Densities range from 1.6 to 2.5 grams/cubic centimetre, with porosities from 30 to 43 percent. The percentage of magnetic minerals values range from 0 to 75 percent, slimes (clay minerals) values of 0 to 26 percent and non-magnetic minerals from 20 to 95 percent. Mineralogical differences in the Mitiwai Formation and Waiuku Blacksand Member cause bimodal populations in the density, magnetic minerals, nonmagnetic minerals and slimes plots. The Mitiwai Formation has higher non-magnetic mineral values and lower density, slimes and magnetic mineral values than the Waiuku Blacksand Member.

Jan 1, 2001

By N. A. C. Smith

The Bureau of Mines motor gasoline surveys have been conducted in January and July, during 1920 and 1921. The Bureau has obtained and analyzed samples of gasoline representative of that marketed in the larger cities. These surveys have indicated that the gasoline on the market during the winter months is more volatile than that sold during the summer months. Naturally, the motorist desires a more volatile gasoline in the cold winter months, as it affords greater ease in starting. The fourth semi-annual motor gasoline survey, conducted during the month of July, shows an interesting relation between the market price and the quality of motor gasoline. This is particularly evident if figures obtained today are compared with those of a year ago. At the time the Bureau of Mines conducted its summer survey of motor gasoline last year, the average tank wagon price of gasoline was 28.2 cents per gallon. This year it was 21.2 cents, a drop of practically 25%.

Jan 1, 1921

By E. Douglas, D. N. Collins, J. R. Stevens

E. Douglas (Dept. of Scientific and lndustrial Re-search, Warren Spring Laboratory, Hertfordshire, England) — The authors are to be congratulated on the considerable improvements they have made in tailoring efficiency and selectivity terms which are generally superior to the alternative forms in current use. However, I feel that their efficiency expression is limited to lower-grade feeds; its accuracy reduces as the feed grade increases. For example, its application to such processes as the beneficiation of glass sands, refractories and clays will invoIve considerable inaccuracies. The reason for this lies in the direct use of recovery, which, with high-grade feeds, biases their empirical expression, R(1 - c/h). With a 90% grade feed, the recovery weighting for the slightest degree of beneficiation, over a zero efficiency sampling operation, will be 90+%+ I disagree with their second basic requirement which states that there can be no fundamental basis for any single quantifying expression. A formula giving a comprehensive representation of concentra- tion efficiency can be derived fundamentally accord-to the procedure outlined in the literature. '' This formula, called the Basic Efficiency formula, is

Jan 1, 1963

By Charles Zahn

Direct mass spectrometric determination of alcohols in the presence of hydrocarbons has not been possible because of the similarity of hydrocarbon and alcohol mass spectra. Experiments have demonstrated that by converting the alcohols to their trimethylsilyl derivatives, characteristic mass spectra are obtained free of interference from hydrocarbon ion fragmentation. Hexa- methyldisilazane is the reagent selected for the conversion, An improved method of preparing the reagent is given, Mass spectrometric determination of alcohols as trimethylsilyl ethers now is not only possible without prior separation from other materials, but the range of the room-temperature mass spectrometer is also extended to include the C10 alcohol region. Water does not interfere because it is converted to hexamethyldisiloxane, which has its own distinctive mass spectral peak, Experience indicates that other compounds such as glycols, amines, and phenols probably could also be determined by mass spectrometry of their trimethylsilyl ethers. Studies on the similar detemination of phenols in coal oils have been started, When mass spectrometry is not available, gas-liquid chromatography of alcohols before and after their conversion to the trimethylsilyl derivatives probably could be performed. The preparation and properties of the trimethylsilyl derivatives of 23 alcohols, 2 glycols, 3 amines, and 1 mercaptan are detailed. INRODUCTION During investigations by the Bureau of Mines at the Pittsburgh Coal Research Center relative to the development of Fischer-Tropsch processes, complications were encountered in the mass spectrometric analysis of alcohols in hydrocarbon oils. The fragmentation peaks of the alcohols and the hydrocarbons were so similar that an accurate analysis was not possible, Since involved separation techniques are necessary to isolate alcohols from hydro-carbons for separate determinations, efforts were turned to the search for a

Jan 1, 1962

Reduce respirable dust exposure of workmen operating auger-type continuous mining machines. Approach: An auger miner was fitted with an exhaust system which draws dust laden air through a [scruber] and discharges it behind the line curtain. How It Works: Dusty air is drawn into the space above the coal conveyor and through a scrubber, by two fans mounted side by side above the conveyor. Exhaust from the fans passes through a duct to the side of the auger miner, and into tubing that runs back and into the air return passage formed by the line curtain. See Figure 1. Of the 5,000 cubic feet per minute of air normally entering the working place, 4/5 is drawn out through the dust exhaust system. The system was installed on a Wilcox Mark 20 Miner and tested underground by personnel of the Bureau's Pittsburgh, Pa., Mining and Safety Research Center, under a cost sharing

Jan 1, 1976

In gold ores, the range of value disclosed by ordinary mine sampling is very wide, and the number of 'samples required for a reliable average is correspondingly great. Even where a large number of samples is available the weighted mean value of the samplesalmost invariably exceeds the true gold content. In operating mines this disparity is overcome by arbitrary reduction of high assays until reconciliation is achieved, but it is frequently necessary, especIallyin exploration, to base an estimate or to reach a decision on a relatively small number of samples from underground openings or even on a few drill hole intersections. In these circumstances, a decisive influence may be exercised by the weight allowed to high assays and to low grade intersections, both of which events are, of course, dependent on the metal distribution in the ore. Where sufficient data are available, statistical analysis will measure the risk involved, but as this information is seldom to be had, the final choice becomes largely a matter of personal judgment.With this problem in mind, a study was made some years ago of the distribution of values in four Western Australian gold ores, with the primary purpose of learning from actual ore-bodies of differing types, something of the metal distribution in the smallquantities of ore involved in individual routine mine samples, and of the importance in each case of high assays. Adequate and suitable data were available in .four cases, in three of which high assays were of frequent occurrence due to the presence of free gold. The results give concrete expression to well known differences of metal distribution, and it is proposed, firstly to record the observed distribution; secondly to examine some of the consequences of the differences in the distributions limd thirdly, to comment, in the light of this data, on the vexed question of the treatment of high assays. Standard statistical procedure was employed in the compilation of the data. The assays were classified by value into groups, each group covering a range of value of 1 dwt. per ton. Assays of less than 1.0 dwt. per ton form the first group; assays equal to or greater than 1.0 dwt. and less than 2.0 dwt. comprise the second group; those equal to or greater than 2.0 dwt. and less than 3.0 dwt. appear in the third group; and so on. Where the number of samples is large, it can be assumed that the mid-value of the group is the mean value of all the samples in the group, thus the mean values of the first three groups are 0.5 dwt., 1.5 dwt. and 2.5 dwt. respectively.The number of samples in the group is the frequency of the group, but for convenience of plotting this frequency is converted into percentage of all the samples in the series. Plotting percentage frequency as ordinate against dwt./ton as abscissa results in a frequency curve-a curve showing the frequency...

Jan 1, 1950

By M. S. Miller

With prevailing assumptions that plentiful domestic coal reserves will be available for meeting our Nation’s expectations for on future low emission, coal-fired power plants, major government funding in Clean Coal Technology, and Carbon Sequestration Programs continues to be aggressive. However, after more than a decade of cutbacks in funding for domestic coal-related programs and personnel, there is a growing concern that adequate quantification and qualification of our Nation’s coal reserves is increasingly being compromised. This paper will define the growing concerns and dichotomies that continue to increase, and address the decreasing number of fossil fuel mapping and assessment programs by Federal and State programs.

Jan 1, 2004

By D. C. Kaliampakos, A. K. Moutsatsou, J. K. Skotaras

The wastes from marble extraction in the Thasos- Kavalla-Drama region of northeastern Greece could be utilised as a new source of high-quality white carbonate fillers for the European market. Large deposits, satisfactory properties, acceptable processing costs and environmental benefits are among the factors that would have a positive bearing on a proposal for their use in this way. DTH, the waste arising from dolomitic marble quarrying operations on the island of Thasos, appears to be the more suitable material than DA waste from Nikissiani on the mainland because of the lower cost of primary grinding and the higher production rate of ultrafines with a mean particle size of 5 micrometres (the optimum size for filler properties in the case of both DTH and DA), its superior whiteness, the benefits that such use would bring to a very severe and complex environmental problem and the lower transport cost

Jun 18, 1905

By Donald R. Johnson

Apparatus providing simultaneous differential thermal analysis, thermo-gravimetry, and evolved gas analysis, has been developed by the Bureau of Mines specifically for thermal study of oil shale and other solid, natural fuels. The apparatus is described in detail, and simultaneous analyses on a single sample of an oil shale mineral, nahcolite, and a thermal analysis demonstration compound, calcium oxalate monohydrate, are presented to demonstrate the instrument's capabilities.

Jan 1, 1970

By John G. Henning

The Hoyle Pond underground mine is located in the Porcupine Gold Camp, 18 km east of downtown Timmins. Since the initiation of production in 1985, the operation has produced in excess of 1.9 million ounces of gold at a grade of 15 grams per tonne. Currently, Hoyle Pond ranks 8th in total ounce production for all past and present producing mines in the camp, with the highest head grade of any of the significant past, or present producing mines in Timmins. Cut and fill, shrinkage, longhole and panel mining methods are employed to excavate the narrow gold bearing structures. Using illustrative examples, this paper provides an overview of factors, such as geologic setting, rock mechanics challenges and mine infrastructure, which influence mine design at Hoyle Pond.

Oct 1, 2004

Mining is both a high risk and a long term business. This is dramatically illustrated by the fact that, on average, the explorer will expend over $30 million in a ten year period for each significant economic discovery. The time required to complete the exploration process is one of the most substantial commitments made by any mining company. For example the time lag between the implementation of an exploration programme and an economic discovery is variously estimated to take two to ten years. The ore definition phase following discovery currently takes between two and five years while subsequent mine development may take one to two years in easy situations and up to 8 in difficult environments. In most countries the critical path through the early stages is determined largely by technical considerations but in almost all countries the path through the later phases is dictated by the plethora of permits, licences and community involvement steps.

Jan 1, 1982

By N. D. L. Burger

An effective prototype face support system to minimize rockfalls in rockfall-prone mines was developed and patented during a project sponsored by the Mine Health and Safety Council (MHSC). An experimental development model (XDM) roof support unit was developed and evaluated. Mines with rockfall problems in the face areas can use the roof support system to reduce fatalities and injuries in the face area of stopes. The roof support system consists of two similar support units connected to each other via two crank mechanisms. Each unit consists of a headboard supported by a ?wishbone? structure (top and bottom leg). In the first design a threaded bar with struts similar to a scissors jack keeps the legs apart. (In the final version that was field trialed, the threaded bar mechanism was replaced with a hydraulic cylinder). All the components are manufactured from steel. To move the system forward the first support unit is collapsed, the second remaining in the loaded position. The first unit then hangs from the second unit to which it is connected. The first collapsed unit is then manually cranked forward and prestressed. If the required position is still not achieved, the other unit is released and moved forward. The specification for the system was determined and presented at a workshop with industry participants. Different concepts were developed and evaluated against the system specifications. A technology demonstrator was then developed and tested on surface. The technology demonstrator development process included detail design, building and testing of components and subsystems, design reviews and the building and commissioning of the technology demonstrator. The testing of the technology demonstrator was done in a 500-ton hydraulic press, in a mock-up stope and underground. A risk analysis, in which technical, logistical and economic aspects were assessed, was done to determine the critical areas of the system. During the next phase of the project working prototypes were developed for underground tests and evaluation. This process indicated that it was necessary to adjust the system specifications and a redesign was called for. In an iterative process test units were built for purposes of evaluation, specification verification and field trialing. After the successful conclusion of the trials the equipping of a complete production stope started for purposes of integrating the system into the current mining process.

Jan 1, 2008

By D. A. Greenwood

Dr David Greenwood opened the first technical session of the conference by highlighting the diverse nature of the papers in this session but drawing attention to the common theme that each solved a particular problem. PAPER 1.1 Tony Elliott introduced his paper on deep mix-in-place soil/cement stabilisation by stressing its simplicity. The engineering solution adopted at Elland was detailed in his paper and had formed the key to success of the project. The process itself is not widely used or known in the UK, although it has the potential to achieve significant benefits, subject to proper engineering control being exercised. It was explained that although the concept was not new, development of the technique for soil modification was relatively recent. The alternatives to mechanical mixing are injection, which is very dependent on soil type, site geometry, etc, and jet grouting; both processes are soil-responsive, and not easily monitored or programmed, difficulties which can largely be overcome by mixing. To achieve this at depths to say 30m requires high-powered, high torque machines and has resulted in significant equipment development.

Jan 1, 1991

Three complete connector assemblies and ten separate contacts were submitted to a series of tests to establish the connector permissibility and compliance with the Bureau of Mines' research Contract H 0110423. Test Procedure TPC-0100 was coordinated, and the test plan approved by the Bureau as fully complying with the intent of the contract for the low voltage, medium voltage and high voltage A.C. connectors. The components and connector assemblies have been demonstrated in testing that they meet or exceed all the requirements of the test procedure.

Jan 1, 1972

By Baha Abulnaga

Slurry pipelines are used in a number of countries to convey processed ore mixed with water over long distances from remote mine sites to ports or plants for further processing. In Egypt and Sudan, numerous mineral resources are scattered in remote areas. Through the years, Egyptian geologists have identified 268 sites for metallic ores and 386 sites for industrial nonmetallic minerals. A large portion of these sites are in the Eastern Desert in an area called the Nubian Shield. Similar sites are found in the Sudan where mining contributes to less than 1 percent of the gross domestic product (GDP). There are three important components of infrastructure needed to develop these resources ? power, water and transportation. While Egypt is able to satisfy 70 percent of its needs in iron ore from the Gadideh Mine in the Western Desert, it needs to expand its other resources to reduce imports heavily sedimented. Dredging of these sediments and transporting them by slurry pipelines would enhance an industry of bricks or agricultural development based on tailings technology often used in mining. This article explores the potential for slurry technology for opening new mines in the desert or recuperating the sediments of the Nile. The technology by itself would be new to both countries and would benefit from collaboration, particularly to de-silt the Nasser-Nubia Lake.

Jan 3, 2010

By L. Villa, O. Suarez, D. Arias, L. G. Corretge

The deposit comprises two vertical, lenticular bodies emplaced in the allochthonous block of a Variscan thrust. Epigenetic mineralisation occurs as replacement of carbonated volcaniclastic rocks of Cambro-Ordovician age. The dominant sulphide minerals are sphalerite and galena with minor chalcopyrite; the main non-metallic mineral is quartz and there is hydrothermal silicification, chloritisation and sericitisation. Sulphur isotope values for sphalerite and galena are heavy and reflect the fundamental relationship between delta-34S in ZnS and in PbS, suggesting isotopic equilibrium. Four sphalerite-galena pairs yield temperatures between 163 and 218 degrees C, in good agreement with the 187-207 degrees C estimated by the Ga/Ge-sphalerite geothermometer. The ore sulphide was leached by the hydrothermal solution from diagenetic pyrite in the host rocks and disseminated sphalerite and galena in Cambrian carbonates

Jun 19, 1905