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By John C. LaScola

The Bureau of Mines investigated coal storage silos to determine how gassy coal must be for methane accumulations in a silo to become hazardous and where such accumulations are likely to occur. Methane concentrations were measured in the open space above the stored coal pile, in the pile, and in the reclaiming area. No methane layering was found in closed-top silos. Reclaiming areas were as gassy as the top part of the silos. Coal samples were collected from the conveyors entering the silos in order to assess the gassiness of the coal. No simple correlation was found between the gassiness of the coal stored and the measured methane concentrations. However, at mines where the average 24-hour gas emission from the conveyor belt samples was 14 ft3/ton or more, fans or open tops were used. It appears that a large fraction of the methane released during storage remains in the void space between the coal particles.

Jan 1, 1980

By Michael W. Neill, O&apos

Drilling slurry has become an effective aid to the construction of drilled shafts in caving and/or waterbearing soils. Historically, drilling slurry made of bentonitic clay and water was first used in the US in water well drilling as early as 1889. In coastal Texas drilled shaft contractors began using slurry, often made of on-site clay mixed with potable water, in the years following World War II, on a relatively routine basis. This type of slurry was used to "process" boreholes, in which the borehole was drilled "in the dry" until water or unstable soil was encountered, after which water and on-site clay were introduced into the borehole and mixed in place with the auger or other drilling tool. Drilling then continued under a slurry consisting of the uncontrolled mixture of clay and water until the excavation had reached a relatively impermeable and cohesive material. At this point, a steel casing was dropped into the hole and sealed into the lower stratum of impermeable geomaterial (soil or rock). The slurry inside the casing was bailed or pumped out, drilling continued to plan depth in the dry, a reinforcing cage was set in the partially cased borehole, concrete was placed and the casing was withdrawn. Some soil-slurry was undoubtedly trapped between the casing and the borehole wall, but the quality of that slurry was usually of no concern, because engineers of the period usually viewed drilled shafts as nothing more than deeply buried footings. Any unejected slurry would only serve to lower side shearing resistance, not yet considered in design, but would have no effect on end bearing. In the 1960 's the effectiveness of soil-slurry came into question because it was often ineffective in maintaining borehole stability at marginal drilling sites and because the economy of using shaft resistance, in addition to end

Jan 1, 1991

By Qing Bo

In this study, the cobalt oxide precursor was prepared in open-style reactor in the condition of high reactant concentration, and then the precursor was decomposed to obtain the cobalt oxides (Co3O4). The effects of some factors on the cobalt precipitation, the particle size and size distribution, and the micro-morphology were addressed. The factors studied include cobalt concentration, initial pH of solution, temperature and time for the reaction, the charge amount of urea, and the temperature for decomposition. It is determined that the precursor particle is in the chemical composition of Co2(OH)3Cl with fine crystalline. By calcinations under proper conditions, the mono-dispersed cobalt oxide particles were prepared with fine crystalline, about 2 µ m in particle size and regular shape in morphology.

Jan 1, 2006

By André Xavier, Edim Bahamonde

En las últimas décadas ha habido un aumento del otorgamiento de concesiones mineras por parte del Estado peruano; sin embargo, paralelamente se ha incrementado el número de conflictos sociales. Ante este panorama, es necesario promover la participación de las comunidades a través de la conformación de comités de monitoreo ambiental participativo, como una herramienta que fortalezca las relaciones de confianza entre las empresas mineras, las comunidades y el Estado, de manera que se genere progreso en la línea de los Objetivos de Desarrollo Sostenible. Este estudio presenta los casos de los comités de monitoreo ambiental participativo de Orcopampa (Arequipa), Juprog (Ancash) y Mallay (Lima), como referentes de buenas prácticas que aportan al mejoramiento de la prevención de conflictos socioambientales.

Sep 20, 2019

By Cawte D. C, Just G. D, Whitchurch K. D

The stringent marketing specifications included in coal contracts mean that coal producers must supply cleaner and more consistent coal than may have been formerly required. Geostatistics has the potential to aid in the accurate estimation of the washability characteristics of coal. A prediction method, the Kriged Service Variable Approach has been developed.A Computer Aided Drafting and Design system has proved useful in the development and application of the approach. The geostatistical approach has been tested against coal geological and borehole data and applications discussed.

Jan 1, 1987

By Elizabeth Cruz

The paper point out innovative energy management techniques that lead to energy recovery and uses it back in the process as heat, mechanical work or power with a consequent impact on operating cost and operating cost and operation cost and a reduction in the overall enviroment impact.

Sep 14, 2009

By Keith R. Vining

Solid fuel, usually coke or anthracite, is commonly added to ground iron ore fines in the pelletising process to reduce the amount of burner fuel required and the maximum firing temperature, while maintaining pellet strength and the productivity of the pelletising plant. However, the use of coke and coal contribute to the production of greenhouse gases (eg carbon dioxide) and are a source of NOx and SOx emissions. Utilising wood biomass / wood char is one methodology CSIRO Minerals is investigating as an alternative to coke and coal, as it is a renewable energy source that is very reactive, has a low ash content and the potential to reduce emissions of greenhouse gases from the iron and steel-making process. Previous work has established that charcoal can effectively replace coke in the sintering process (Lovel et al, 2005), and the following experimental work aims to demonstrate that it can also provide an adequate replacement for coke and coal in the pelletising process. The paper presents the results of an experimental testwork program comparing the behaviour of fired pellets containing traditional solid fuels and charcoal. The physical properties of the pellets are compared in terms of their compressive strength, tumble and abrasion indices and the reduction properties. A qualitative assessment of the pellet microstructures is also presented.

May 1, 2007

By Rob Famlield, Gavin Yuill, William Birch

The Blasting Research Group at the University of Leeds, in the United Kingdom, continues to be highly active in the area of the environmental impact of blasting. In recent years a major part of this research has been concerned with the use of linear superposition. This technique relies upon the assumption that all the holes in a blast produce identical vibration signals. Previous work at the University has shown that this assumption is not sufficiently robust to be generally applicable. This is due to a number of factors of which the key variable appears to be dynamic confinement

Jan 1, 2002

Mine Terex articulated dump trucks are working on a large restoration project of an abandoned open cast coal site in Blacklaw, central Scotland. The project is part of the construction of a 42-turbine wind farm complex. During the scheduled 18-month duration of the project, three 28-t(31-st) Generation 7 TA30 dump trucks and the six 36.5-t (40-st) TA40articulated trucks are estimated to move about 1Mm3 (1.3 million cu yd)of material. The trucks are working12-hour shifts, 5.5days a week.

Jan 1, 2005

A computerised cataloguing system for geological specimens is described. The catalogue is designed for use with a compactus-type storage system. The information stored in the catalogue for each specimen includes the type of specimen, locality information in terms of standard ~ap sheets and descriptive location, geological age, stratIgraphy, and specimen descriptions. The catalogue can be interrogated at any level of detail on the basis of any combination of these specimen parameters.Other information stored for each specimen 'is the compactus address, collection date, reference information and the type of analyses performed on that specimen:Any mterrogatlon produces a listing of those specimens which satisfy the search criteria.

Jan 1, 1974

By R. L. Virta

Four companies mined ball clay in four states during 2005. They included H.C. Spinks Clay (owned by Franklin Minerals), Kentucky-Tennessee Clay (owned by Imerys), Old Hickory Clay and Unimin. Production was estimated to be 1.32 Mt (1.45 million st) valued at $53.3 million, based on the results of a preliminary survey of the ball clay industry. Production in 2004 was 1.22 Mt (1.34 million st) valued at $54.1 million. Tennessee was the leading ball clay producer state with 61 percent of domestic production, followed by Texas, Mississippi and Kentucky.

Jan 1, 2006

By Alan D. Hartman

Standard metering of electric arc furnaces usually uses root mean square (RMS) or true root mean square (TRMS) measurements for determining power. Only sinusoidal signals are accurately described by RMS meters, and dc or high-frequency components normally are lost in standard TRMS metering. This can lead to inaccuracies when electrical signals are not sinusoidal, contain dc components, or include fast risetime perturbations, as is the case with the electric signals from an electric arc furnace. Electric arc furnace electrical waveforms, observed in research carried out by the U.S. Bureau of Mines, show high-frequency components and significant deviations from sinusoids. These perturbations and distortions make metering difficult for standard power meters. The inaccuracies in metering can cause further problems if those sensors are used in control systems. For control strategies requiring rapid response, any averaging scheme loses information that can be used in control decisions. In order to obtain better signals for both monitoring and control, a study of instantaneous, RMS, and TRMS power monitoring devices was conducted. From this study it was concluded that precision integrated circuits should be used to obtain instantaneous power with a bandwidth of at least 25 kHz. The information from these devices is more representative than that of standard meters and can be used in predictive control.

Jan 1, 2010

By Gang Guo, Zhong Liu, Yi Zhang, Jingchun Lu

"Abstract Application of soil displacement screw pile (known as SDS pile) has been experiencing accelerated growth in Chinese deep foundation industry because of its technical advantages, environmental benefits, and cost effective as well. As bored displacement piling, SDS piles are able to perform better than non-displacement piling such as CFA plies due to changing the stress state in the soil around SDS piles during the installation. Therefore the design methods between the conventional pile type and SDS pile type have some differences. Based on the methodology research, current Chinese piling rigs, displacement augers and piling projects are introduced, and the current design approaches for SDS piles in China are also described. Moreover, the design results are verified by using full scale load tests, and a part of the research results of SDS piling system acquired in China are presented.IntroductionThe Continuous Flight Auger Pile, also known as the CFA pile, has occupied about 22% in the pile market all over the world (Van Impe, 2004; Bottiau, 2006). The CFA piles are usually used for large diameter (600mm~1200mm) pile foundations and deep excavation projects. Whereas the small size CFA piles (400mm~500mm) are mainly applied for composite foundations in China. In the past 10 years, the new technology of soil displacement screw piling has been applied worldwide (Prezzi et al., 2005). And it is also extensively used for high-rise buildings, industrial plants and railway projects in China (shown in Figure 1)."

Jan 1, 2014

By J. V. Batty

Radioisotopes of selenium (se78) and tellurium (Te123) were successfully employed by the Bureau of Mines as tracers in metallurgical research directed to developing improved methods for volatilizing these elements from low-tenor raw materials. Prior research, guided and controlled by conventional analytical methods, was seriously hampered by inconsistent selenium and tellurium analyses, by the slowness of the conventional chemical methods, and by the poor accountability of these volatile elements in test products. Methods were devised and evaluated for admixing the radioactive tracer with typical raw materials and then following the deportment of the selenium and tellurium by radiometric methods with occasional chemical analysis checks. These techniques were found unusually effective in (1) quantifying the completeness and the rate of volatilization of selenium and tellurium while heating the raw materials at different rates to different temperatures and (2) accurately tracing and quantifying the distribution of minute amounts of these volatile elements in the several products made by high-temperature treatment and in the several units comprising the experimental equipment.

Jan 1, 1962

How did you get into mining; were you from a mining town or mining family? Not at all. I grew up in northwest Kansas. I liked to hunt and fish, so I thought it would be fun to work for a company that made knives or guns. It seemed like metallurgical engineers would be something those companies could use, so I started in physical metallurgy. I got a summer job at the great Climax molybdenum mine near Leadville, CO shoveling muck onto conveyors. I was hooked. I loved everything about mining, so in the fall, I changed majors from physical metallurgy to mineral processing. For many years you actually discouraged young people from studying the mining disciplines. Could that be right? That’s true.

Jan 1, 2007

By Secretary of the Interior

"INTRODUCTION The Bureau of Mines Synthetic Liquid Fuels Program again forged ahead during 1952, and important technical advances led the way to improved methods of converting coal and oil shale into liquid fuels. Marking the eighth year of activities under this program, the past 12 months brought a new domestic industry nearer realization.The increasing demand for gasoline and oil and the rising cost of finding new petroleum, coupled with America's growing dependence on imports and the unsettled international situation, have continued emphasize the importance of the Bureau's Synthetic Liquid Fuels Program. Oil, the indispensable material of wartime, likewise has critical importance in peacetime, touching as it does the life of every individual. Supplementing petroleum with synthetic liquid fuels will not only conserve this Nation's petroleum reserves but also will bring into greater use its tremendous reserves of coal, as well as the vast deposits of oil shale for which no other practical use has yet been found.The Bureau of Mines Synthetic Liquid Fuels Program is one of the most important and far-reaching of the Government's research projects. Through development, of commercial synthetic liquid fuels, the United States can obtain oil products from its great inland reserves of coal and oil shale to supplement petroleum in any quantity that may be necessary, consistent with economic and other requirements, such as national defense. The use of raw materials from such deposits would be of highest importance in wartime, when shipping lanes are menaced by the enemy. The Synthetic Liquid Fuels Program of the Bureau of Mines and research efforts of industry have advanced American technology to the point where it is now possible to begin the design and construction of prototype plants. Certainly, significant improvements will be made as the program continues, but this prospect in no way alters the fact that the start of prototype plants should be encouraged. These plants, as the first step in the development of a synthetic fuels industry, would serve a threefold purpose:"

Jan 1, 1953

According to reports in August, Botswana RST's copper- nickel-cobalt smelter at Selebi-Pikwe produced 7 percent above the rated capacity of about 3,500 metric tons of matte per month. This record production occurred after 2 years of plant production difficulties and was brought about by a new management team. A shutdown for furnace maintenance had been planned for this year, but was postponed because of the improvements in production and operations. However, the mining operation continued to face problems relating to higher costs and some outstanding claims. COPPER: Effective December 1, ASARCO, Inc. and Phelps Dodge Corp. reduced their domestic copper prices by 54 per pound. Within a period of 3 days, a11 other producers (Kennecott Copper Corp., Newmont Mining Corp., Cities Service Co. , Copper Range Co. , Duval Corp., and Inspiration Consolidated Copper Go. ) had either lowered or discounted their market postings by 5¢ to 65.625¢ per pound on electrolytic wirebar and 65$ on cathode plate. Between November 29 and December 3, New York merchants decreased wirebar quotations by 1.8¢-2¢ to within a range of 57.8¢-58¢ per pound. New York Commodity Exchange (COMEX) spot-contracted copper in the week was priced at 57. 1¢ on Monday, 56.7¢ on Wednesday and Thursday, and 57.4¢ on Friday, resulting in a 5-day average of 56.9¢, London Metal Exchange (LME) cash (prompt) wirebar averaged 56.3¢ last week, opening Monday at 56.6¢, falling from Tuesday?s high of 57.2¢ to Wednesday?s low of 55.6¢ and closing Friday at 56.1¢. Foreign producers, guided by LME market transactions, lowered wirebar quotes to 56¢ per pound. Copper stocks as of December 3 totaled 187,702 short tons at COMEX warehouses and 654,573 tons at LME depositories, compared to 97,413 and 537,481 tons, respectively, for the corresponding 1975 period.

Jan 1, 1976

By James C. Fowler

As report covers the installation and testing of a permanent seismic monitor system at the Loveridge Mine in West Virginia. The testing of the system showed several things: 1. Getting the seismic data hack to the central computer in a usable form is possible 2. It is possible to detect small explosions. 3. The use of this system as a auxiliary system to detect hammer blows from miners trapped in the area of one of the geophones is possible.

Jan 1, 1974

By Steve Custer, Tim Kahl, Sue Parker

"The primary objective of the Barrick Goldstrike expert system is to achieve the desired liberation size for the autoclave circuit while maximizing throughput. In addition, when downstream limitations (autoclave circuit or others) restrict the milling circuit tonnage the expert system further improves grinding product size. Since its implementation, the expert system has provided expected throughput improvements while improving or maintaining circuit performance.Barrick Goldstrike and MinnovEX Technologies Inc. teamed up to install an expert system to control Line I and I1 of the autoclave grinding circuits. The dissimilar equipments of the two grinding circuits coupled to different production objectives, skepticism among operators, and the variability of the ore types processed in each line challenged the implementation.To ensure implementation success, Barrick Goldstrike dedicated four administrators full time to the project. The system administrators included two metallurgists, a process control engineer and a mill trainer. As usual, the control room operators were the experts who provided the operational logic for the foundation of the control system. The administrators and all eleven of the control room operators signed off on acceptance of the system. Current online utilization is 95%.INTRODUCTIONThe grinding circuit for Barrick Goldstrike’s autoclave process consists of two SAG Mill Ball Mill lines. Line 1 grinding circuit is comprised of a 22 by 8 foot, 2500 horsepower Allis Chalmers (AC) variable speed SAG mill, followed by a 12.5 by 14 foot, 1250 horsepower AC ball mill, and a 13.5 by 18 foot, 1800 horsepower Dominion ball mill in parallel. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1352 Nordberg Omnicone crusher (4.5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The ball mill circuit is closed with 6 Krebs super D20 cyclones. Line 2 grinding circuit is comprised of a 24 by 12 foot 4000 horsepower Fuller variable speed SAG mill followed by a 16.5 by 30.5 foot 5000 horsepower Fuller ball mill. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1560 Nordberg Omnicone crusher (5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The line 2 ball mill circuit is closed with 12 Krebs super D20 cyclones. The underground Meikle ore is typically fed through Line 1. Achieving the desired product size is critical for successful processing of Meikle ore. Open pit Betze ore is fed to Line 1 when Meikle ore is unavailable. Line 2 processes Betze ore exclusively. Throughput is maximized when processing Betze ore as the product size is less critical. The products of these two circuits are combined as feed to the autoclave circuit. The ore types and the autoclave circuit demands determine the required grinding circuit product size and maximum combined mill feed tonnage."

Jan 1, 2001

By Anderson Azevedo Agra

O Pó de Aciaria Elétrica (PAE) é um resíduo sólido gerado durante a fabricação de aços em usinas com Forno Elétrico a Arco (FEA). Esse resíduo contem quantidades apreciáveis de metais, tais como ferro e zinco, tornando sua reciclagem interessante não só do ponto de vista ambiental como econômico. Assim, esse trabalho teve como objetivo avaliar a autorredução de misturas de pó de aciaria elétrica e coque verde de petróleo (CVP). Para isso, misturas e pelotas de PAE:CVP, com variados teores de redutor, foram submetidas a ensaios de autorredução em termobalança e, na forma de pelotas autorredutoras, numa retorta aquecida em forno elétrico vertical. A redução das amostras foi analisada a partir da perda de massa das misturas. Além disso, a redução das pelotas autorredutoras foi observada através de análises de difração de raios X. Nestas análises foi possível verificar decomposição da Franklinita e a redução dos óxidos de Ferro e Zinco.

Aug 17, 2017