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By Dilermando Nagle Travessa

High strength-light weight materials are very attractive for the transportation sector, particularly to the aerospace industry. High strength-age hardenable aluminium alloys are widely used in airframes due to their unique combination of strength, density, toughness, corrosion resistance, cost and easy processing. However, the hardening capacity of such alloys is somehow saturated due to thermodynamic issues related to the conventional processing. The production of aluminum-matrix composites is a promising strategy to overcome this limitation, resulting in strength levels that cannot be reached by actual commercial aluminum alloys. In the present work, multiwall carbon nanotubes were used to reinforce the AA6061 aluminium alloy. 1 and 2% weight percent of MWCNT were mixed to the alloy powder by high-energy ball-milling process. The blended powder was consolidated by hot extrusion. The obtained composite bars were submitted to heat treatment for the T6 condition in order to combine both CNT dispersion and precipitation hardening effects. Optical and scanning electron microscopy, as well as hardeness testing, was used to characterize the bars. Typical wrought microstructure, free of defects, was observed on the extruded bars. Hardness of the composites was observed to increase by 20, 28 and 68% for 1% MWCNT 6 h milling, 2% MWCNT 6 h milling and 2% MWCNT 10 h milling, respectively, in the as-extruded condition. The better performance for the composites blended at higher milling time was attributed to a better nanotubes dispersion. Subsequent heat treatment to the T6 condition did not result in additional hardening.

Aug 8, 2018

By Harmon E. Keyes

Many organizations, including the Bureau of Mines, have made intensive studies of the application of leaching methods to relatively small low-grade disseminated deposits of copper ores, containing both oxide and sulphide minerals. One of the principal difficulties has been to obtain a solvent that could be made at a low cost and would effectively dissolve the copper minerals. Another drawback has been the high initial cost of a plant and the refined type of mechanism ordinarily required by standard practice for carrying out the leaching cycle. The Bureau of Mines has attempted to develop a cheap and efficient solvent that would especially meet the requirements of smaller plants. (See Bibliography.) It has been known that dilute ferric sulphate-sulphuric acid solution is an excellent solvent for most copper minerals, such as chalcocite, bornite, and oxidized forms, but not for chalcopyrite and certain silicates. A method of producing this solution from sulphurous products and waste liquors was developed by the bureau and tried successfully on a test-plant scale at the Southwest Experiment Station in cooperation with the department of mining and metallurgy, University of Arizona, Tucson, Ariz. However, this work did not involve the actual leaching of ores with the solutions thus produced or the cyclic use of the iron solutions in the regenerator cell. Except for certain laboratory tests, in which known impurities were added, no data were available to show the effect on regeneration if accumulations of impurities were built up in the leaching circuit.

Jan 1, 1930

By David J. Kusler

This report describes a primary or direct, continuously sampling, and automatically averaging gravimetric method for analyzing gaseous mixtures of carbon dioxide, carbon monoxide) hydrogen, and (by volume measurement) nitrogen. The gaseous mixture is analyzed by passing it at a controlled and definite rate through a system that permits carbon dioxide and water retained by appropriate absorbents to be determined and the residual-gas volume (essentially nitrogen) to be measured. The accuracy and dependability have been established by comparison with very carefully conducted Orsat analyses. The method was developed for, and has been satisfactorily applied to, the analysis of blast-furnace top gas. It permits relatively attention free operation, using simple and low-cost materials usually found as basic equipment in the analytical laboratory. It provides, over a wide range of time or sampling intervals (from less than 1 to over 24 hours), the average composition, in terms of volume-percent, for those components usually determined in blast-furnace gas, if (as is usual) the flow rate of gas from the blast furnace is essentially constant over a selected analysis interval. Oxygen and methane are not determined; but, since these gases are normally absent or present only in traces, their analysis is seldom required.

Jan 1, 1959

By O. C. Blade

The use of Diesel fuel as a source of power is continuing to increase in the United States. The latest available figures indicate that refineries are delivering in excess of 10,000,000 barrels of this type of fuel per month. Factors contributing to this increased consumption are conversions by a number of railroads from steam to Diesel locomotives and the growing use of Diesel engines in buses, trucks, tractors, earth-moving machinery, water craft, and stationary power plants. The increasing importance of Diesel fuel has led to a need for more information on its characteristics, particularly on the grades and qualities currently being marketed. To supply this information the American Petroleum Institute and the Bureau of Mines, United States Department of the Interior, under a cooperative agreement, are conducting annual surveys of Diesel fuels produced in refineries in this country. Samples of Diesel fuel were analyzed by the manufacturers in accordance with instructions from the Motor-Fuels Survey Panel of the Automotive Research Committee of the American Petroleum Institute. Results of the analyses were transmitted to the Bureau of Mines where the data were studied am compiled as shown in the tables of this report. The first survey was made in 1950 and was published as a Bureau of Mines report. The present report shows the results of a similar survey made during 1951.

Jan 1, 1951

By Oliver Bowles

[The inorganic nonmetallics - that is, all minerals aid their primary products except metallic ores and fuels - have an important place in industrial life of any country. They are essential to a multitude of products and processes, and their development is closely related to general industrial activity. Several are classed as strategic, and many others are performing necessary functions in the military program. It may be of interest therefore to trace their history over a period of years and to correlate their progress with the circumstances and events that are shaping national]

Jan 1, 1943

Industrial minerals enjoyed a fairly successful year in 1978, despite the sluggish economy, inflation, and environmental restrictions. A glance at US Bureau of Mines statistics shows that, in general, production of industrial minerals increased from + 1% (salt) to as much as 26% (sulfur, other than Frasch or recovered). A few industrial minerals showed a decline; fluorspar production, for example, registered a 23% decrease in 1978 from 1977 due to the closing of three domestic mines. Bromine, natural sodium sulfate, Frasch sulfur, and vermiculite also had production decreases of 2-6% in 1978.

Jan 5, 1979

By C. A. Rowland

The rising costs for and the possibility for limited availability of electrical energy are emphasizing the continual conflict faced in the selection of comminution circuits used in preparing ores for concentration, namely; capital cost vs. operating cost. Frequently, the circuit with the lowest capital cost is not the most efficient in the use of electrical power and wear resistant materials. The simplest circuit in terms of flow, pieces of equipment and capital cost is the single stage autogenous or partial autogenous circuit used to grinding primary crusher discharge or run of mine ore to the desired product size. (Fig. 1) From this circuit, complexity increases to multi-stage crushing circuits preparing feed for multi-stage grinding circuits. Fig. 2 showing a three stage rod mill ball mill arrangement is an example of a complex grinding circuit. Stage concentration further complicates the flow. Multi-stage circuits being the most expensive to install, often give the greatest operating flexibility and offer the best possibilities for the most efficient use of available power and wear resistant materials. Within available grinding circuits, other comparisons such as high speed vs. low speed mills, grate discharge vs. overflow discharge, metal liners vs. rubber liners, high charge vs. low charge, etc. all add to the conflict

Jan 1, 1977

By Kwangmin Kim, Junnhyeok Park, Taehee Lee, Minkyu Kim

Mine tailings storage facilities (TSFs) can be a significant source of fine, respirable dust. This dust poses concerns, especially for nearby communities, because of its detrimental impact on respiratory health. To address these concerns, this study examined the effectiveness of commercially available polymers, known for their biocompatible and environmentally friendly features, to prevent dust generation from upstream-type TSFs in active mining operations. It focused on two areas in TSFs: the tailings beach and slope/dike surfaces. Two types of polymers—polyethylene glycol and poloxamer—were selected, and their effectiveness was evaluated in a series of phased laboratory and field tests. The lab tests investigated the moisture-retention capacity of the tailings after treatment with the polymer solutions as well as the ability of these solutions to reduce dust emissions. Polymers were applied to a tailings bed surface in the lab and dust was generated from this surface using a wind tunnel. PM10 and PM2.5 concentrations were measured using laser-diffraction dust sensors, and the polymers were found to have reduced dust emissions up to 95%. Small-scale wind-blowing tests were conducted in the field (specifically, in a controlled environment at a TSF) to evaluate polymer effectiveness on the tailings beach and slope/dike areas. The tests revealed that the AP could efficiently suppress approximately 80% of PM10 and PM2.5 dust emissions at both types of areas. Finally, 1000 gallons of AP solution were discharged at the top of tailings beach and slope/dike areas, respectively, and found to be effective. The results of these tests showed the high potential of the biocompatible polymers to be a feasible solution for reducing the respirable dust emissions from upstream TSFs in arid and semi-arid regions.

By John Hardy

The performance of five dense-medium washers was evaluated in four preparation plants. Three of the plants were making a two-product separation that produced a clean coal and a refuse; one plant employed dense-medium vessels in series to effect a primary and a secondary separation. The secondary drum-type washer produced a low-ash metallurgical coal and an intermediate-ash product suitable for plant fuel or steam generation. The sharpness-of-separation was excellent for all four primary separations and the secondary separation.

Jan 1, 1966

By Eric S. Weiss

The National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research to evaluate explosion blast effects on typical U.S. mine ventilation stoppings in the NIOSH Pittsburgh Research Laboratory?s (PRL) Lake Lynn Experimental Mine (LLEM). An innovative Australian-designed brattice stop-ping was also evaluated. After mine explosion accidents, MSHA conducts investigations to determine the cause(s) as a means to prevent future occurrences. As part of these postexplosion investigations, the condition of underground stoppings, including the debris from damaged stoppings, is documented as evidence of the approximate strength and the direction of the explosion forces. The LLEM data showed that a typical dry-stacked and coated solid-concrete-block stopping survived a total explosion pressure of ~6.7 psi (~46 kPa) and was destroyed at a total explosion pressure of ~7.6 psi (~52 kPa). In comparison, a typical dry-stacked and coated hollow-core concrete block stopping survived a total explosion pressure of ~3.4?4.3 psi (~23?30 kPa) and was destroyed at a total explosion pressure of ~3.6?5.2 psi (~25?36 kPa), depending on the length of the pressure pulse and the value of the pressure-time integral. A typical steel panel stopping design survived a total explosion pressure of 0.8 psi (5.5 kPa) and failed at a total explosion pressure of 1.3 psi (9 kPa). The LLEM data also showed that an obstacle blocking the path of a pressure wave resulted in a higher reflected pressure at the obstacle. An 8-in (20-cm) thick wet-laid solid-concrete-block stopping coated on one side survived a total explosion pressure of ~26 psi (~180 kPa); this stopping was not tested to failure. A 6-in (15-cm) thick wet-laid solid-concrete-block stopping coated on one side survived a total explosion pressure of ~14 psi (~97 kPa) and was destroyed at a total explosion pressure of ~25 psi (~172 kPa). An innovative Australian woven cloth stopping survived an explosion pressure of 4.0 psi (27 kPa) and was destroyed at an explosion pressure of ~6.1 psi (~42 kPa). These results will help investigators determine the approximate explosion forces that destroy or damage stoppings during actual coal mine explosions.

Jan 1, 2008

By N. D. Ilankoon

"The use of thiosulfate as an alternative lixiviant for cyanide to treat complex refractory ores followed by the use of ion exchange resins (IX resins) for gold recovery has become an industrial reality. In this study, polyethylenimine (PEI) coated iron oxide magnetic nanoparticles (MNPs) were used to recover gold from the leaching solutions that consist of calcium thiosulfate, copper and gold. The gold loaded MNPs were easily separated from the solution using an external magnetic field. Proposing a novel adsorbent with characteristically easy solid-liquid separation, to recover gold from synthetic thiosulfate leaching solutions and gold elution and reuse of MNPs were the main objectives of this study. Adsorption isotherm studies revealed that the data fitted both Langmuir and Freundlich isotherm models equally well. The maximum adsorption capacity was 18.5 mg/g at pH 8 and 50?C. According to thermodynamic studies the physisorption process was exothermic and spontaneous. Gold and copper elution, and the regeneration and reuse of the nanoparticles were investigated and promising results were obtained. Different elution systems comprising sulfites, chlorides, glycine, EDTA (ethylenediaminetetraacetic acid) and sodium hydroxide were considered. Among them, EDTA for copper elution and NaOH for gold elution were the most efficient eluants. Regeneration and reuse studies revealed that the MNPs can be used for several cycles without significant performance loss. INTRODUCTION Although cyanidation has been used for gold leaching for more than 100 years, some major drawbacks associated with cyanidation have led to a quest for alternative lixiviants for gold leaching. Cyanide is ineffective in treating carbonaceous refractory ores as gold cyanide complex is adsorbed onto the native carbon in the ore itself known as preg-robbing. On the other hand environmental concerns associated with cyanidation drives the need for environmental friendly alternatives for cyanide. As of today, thiosulfate is known to be the most extensively studied and most promising alternative lixiviant for cyanide in both technical and environmental perspectives (Aylmore and Muir 2001, Oraby 2009)."

Jan 1, 2018

By A. G. Sharkey

THE PURPOSE of this investigation was to develop methods for analyzing coal derivatives and products from the Fischer-Tropsch synthesis. As part of this investigation it was necessary to study the mass spectral characteristics of many classes of compounds. The mass spectra of alcohols, the trimethylsilyl ether derivatives of alcohols, acetal-type compounds, ketones, esters, and naphthenes were correlated with structure, and analytical methods were formulated. A method was devised to determine the ratio of branched to normal hydrocarbons up to CIS in the Fischer-Tropsch product. Low-ionizing-voltage mass spectrometry was combined with type-analyses to analyze tar acids and neutral oils from coal. The necessary sensitivity correlations at low-ionizing voltage were developed, particularly for phenolic compounds. Special analytical techniques were developed for the mass spectral analyses of specific compounds and compound types including (1) oxides of nitrogen, (2) hydrogen sulfide, (3) isomers of butenes and pentenes, and (4) hydrogen deuteride. An investigation was made of the effects of various hydrocarbons and oxygenated compounds on tungsten filaments in the mass spectrometer. The operating characteristics of rhenium filaments under similar conditions were studied. Several improved sample handling techniques were developed, including an automatic manometer and a self-filling micropipet. Studies were made of anomalous and negative peaks in the mass spectra of certain gases.

Jan 1, 1967

By C. Steve Albrecht

The primary objective of this study is to "evaluate the influences of different equipment systems on prime farmland subsoil compaction due to surface mining in the Midwest." The study is centered on four mine sites each utilizing a different combination of equipment for soil removal and replacement. Subsoil compaction is the primary focus of this research effort. Primarily owing to physical location, it is difficult to alleviate the increased compaction directly below the topsoil in reclaimed soils. Different equipment combinations cause varied effects when soils are replaced during surface mining activities. By collecting field data within a statistical framework, the effects of different equipment combinations on subsoil compaction can be evaluated and conclusions drawn. This research effort evaluates a comparison of natural and replaced soils by moist bulk density data. This comparison centers on changes in bulk density and texture to a depth of 48 inches. For each study site a complete case study is provided for use in data correlation and interpretation. Basis for this research effort centers on four (4) major experiment designs: o Comparison of soil bulk density values for three distinct equipment systems evaluated on the same general soil types (i.e. scrapers, bucket-wheel excavators and end-dump haulback); o Evaluation of the effects of soil replacement in repeated lifts using scrapers; o Presentation of bulk density values representing soil compaction for four (4) equipment systems (i.e. bucket-wheel excavators, draglines, scrapers and end-dump haul back) on four separate mine sites in the midwest; o A prediction analysis model is developed for subsoil bulk density following reclamation based on equipment characteristics and a statistical evaluation of texture. The soil data base of information includes data from the 1982 Bureau of Mines study entitled, "Impact of Surface Mining on Soil Compaction in the Midwest" as well as data from this research project. The final report is synthesized through an analysis of field data, statistical analysis and literature review. The final report focuses on the interpretation of results for practical application by government and industry.

Jan 1, 1984

By M. H. Kline

The Great Gossan Lead in Carroll County, Va., is one of the largest undeveloped sulfide ore bodies known in the eastern United States. It extends for 16.7 miles along the western slope of the Blue Ridge Mountains (fig. 1). The various known segments of the deposit, extending from the southwest end to the northeast, are: The Great Outburst or Iron Ridge segment, Chestnut Creek, Copperas Hill, Sarah Ellen, Wild Cat, Cranberry, Dalton Hill and offset segment to the south of the Cranberry, Little Reed Island, Little Vine, and the Betty Baker at the northeast end. All of these segments have been explored or mined to various extents in the past for the iron gossan and secondary copper ore. The Great Outburst or Iron Ridge segment is now being mined by the General Chemical Division of the Allied Chemical & Dye Corp. for the sulfur and iron content of the primary ore. These deposits are becoming increasingly of Interest as a. large potential source of iron and sulfur owing to their proximity to Birmingham, where the burned cinder sells at a premium, and to the acid markets of the region.

Jan 1, 1949

By Roberto Parreiras Tavares, Leonardo José Silva de Oliveira, Marcelo Moreira Furst Goncalves, Rodrigo Seara Martins

Os pós fluxantes estão continuamente sendo desenvolvidos para permitir que o processo de lingotamento contínuo possa gerar produtos de melhor qualidade superficial. Entretanto, a seleção e a avaliação do desempenho industrial desse insumo não são simples por envolver o conhecimento simultâneo de várias propriedades físico-químicas. Nesse sentido, desde que medido de forma adequada, o consumo do pó fluxante no molde é uma ferramenta útil para avaliar a estabilidade operacional. Assim, foi desenvolvido um sistema para quantificar o consumo específico dos pós fluxantes no molde para posteriormente correlacioná-lo com eventos que possam levar a desvios de qualidade superficial do produto lingotado.

Oct 1, 2019

By F. A. Rutledge, B. S. Webber, J. M. Moss

"INTRODUCTION The United States, with its vast resources of relatively low-grade zinc been the world's leading producer of zinc -metal for many years. The expanded zinc production during the period, 1939-44, inclusive, was induced by favorable premium prices and has depleted the known ore reserves in the United States. The 1943-44 rate of zinc production cannot long be maintained in the United States, especially if premium prices are removed. Domestic zinc reserves, have been depleted to such an extent that it is doubtful if our mines will again be able to completely and continually fulfill the needs of this country.The Bureau of Mines, anticipating a postwar consumer demand for 550,000 to 750,000 tons of slab zinc and an additional 100,000 tons for use in paints and chemicals, sent two engineers to Sedanka Island in July 1945 to investi¬gate the deposits near Biorka Harbor.ACKNOWLEDGMENTIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion the Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director."

Nov 1, 1946

By Yoon-Bong Hahn

A mathematical model has been developed to analyze and predict the reduction process of iron ore particles in a two-stage fluidized bed system. This model includes the effect of particle degradation to elucidate its effect on reduction of iron oxides. Although the particle degradation is dependent on kind of iron ores, it was found that eighty to ninety percent of overall degradation is occurred in the prereduction stage mainly due to thermal stress and volume expansion. The degradation of particles in the?final stage is not much, but is mainly due to interparticle collision and abrasion. It was also found that to obtain a target reduction degree, it is of great importance to control the bed temperature and the residence time of paarticles in R1 rather than in R2. Optimum range of residence time was 15-20 minutes in the prereduction stage; 30-35 minutes in the final reduction stage.

Jan 1, 1996

By W. P. Yana, J. B. Littlefield

"INTRODUCTION AND OBJECT OF EXPERIMENTAn explosion in and rupture of a gas-tight switch box on an electric loader in a mine located near Pittsburgh indicated that the cause was an internally generated inflammable gas-air mixture. This led to the suspicion that moisture condensation or ""other unusual conditions might have caused a spark or are across the surface of the material and that the heat may have created a carbonized path across the synthetic plastic base which would then conduct a large current with the generation of considerable heat and thermal decomposition of the base materials base in the box which exploded gave every indication that this series of events had taken place, and accordingly it was desired to determine what explosive gases such a decomposition of these insulating materials would produce.ACKNOWNLEDGMENTSThe desirability of making this investigation was suggested to the authors by L. O. Ilsley, supervising engineer, electrical section, Bureau of Mines, to whom the occurrence of an explosion in a switch box had been reported. The writers also acknowledge with thanks the assistance of L. B. Berger, chief scientific aide, health laboratory section, Bureau of Mines, in checking the calculations in the tables. DESCRIPTION OF MATERIAL INVESTIGATEDThe ten materials used in the tests, identified by letters A to J inclusive, are described in a succeeding list of materials. All the materials except I had a phenolic odor, especially when freshly cut."

Dec 1, 1932

By Marcos de Paiva Bueno, Leonardo Ribeiro Lara, Rajiv Chandramohan, Thiago de Almeida, Greg Lane

This paper explores the impact of the significant difference between the number of geochemical assays conducted for grade estimation and the number of comminution tests performed for throughput and performance forecasting. Both grade and throughput are key factors in determining the project. We analysed 154 feasibility study reports to assess the impact of sample frequency for comminution test work on project revenue. This disparity in size between assay and comminution data arises because geological and resource-grade risks cannot be managed without extensive geochemical testing, whereas comminution risks are traditionally mitigated through design methods and the use of contingencies. This approach is partly due to the relatively high cost and large sample requirements associated with traditional comminution tests. Our analysis demonstrates that insufficient comminution sampling and testing leads to uncertainties in throughput forecasts, creating significant financial risks. Data from the feasibility studies show that a 1% change in mill throughput can result in up to a 5% variation in Net Present Value (NPV), underscoring the sensitivity of project economics to operational performance. Building on previous work, we reference studies that reveal how low frequency of comminution testing can increase uncertainty in mill throughput forecasts and increase financial risks. We propose an approach that optimises the number of comminution samples tested to enhance forecast accuracy and reduce NPV variance. By adopting this approach, mining projects can improve financial reliability and mitigate risks associated with underperformance in SAG and AG mill-based operations.

Feb 1, 2025

By R. J. Leary

This investigation was conducted to determine the effects of various rare-earth metal addition practices upon the macrostructure and the pattern of sulfur distribution in steel ingots. Heats of plain carbon steel were melted in a 1-ton, basic electric-arc furnace. Melts were treated with mixtures of rare-earth silicides, aluminum, and cryolite either in the furnace before tap or in the ladle after tap to determine the effects of this form of rare-earth treatment upon ingot macrostructure. Steels thus treated with rare earths in the furnace were characteristically free of the gross subsurface nonmetallics which typically result from conventional rare-earth treatments. Steel treated in the ladle showed only a few such nonmetallics, and practical techniques were developed for eliminating most of these. Results showed that furnace deoxidation was controlled by the concentration ratio of rare earths: aluminum. During casting, deoxidation was controlled by the concentration of rare earths. Oxygen contents equivalent to vacuum ladle degassing resulted from air-melt furnace treatments with the rare-earth mixtures described. Rare earths in steel inhibited the onset of equiaxed grain formation during ingot freezing, and also virtually prevented interdendritic segregation of sulfides.

Jan 1, 1968