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By Yuanping Cheng, Jingyu Jiang, Qiang Zhang

"With the increase of mining depths, deep-seated coal seams face threats from high ground stresses, high gas pressures, high gas content, and low seam permeability, which significantly increase the likelihood of coal and gas outbursts. Challenges continue to grow in coalbed methane (CBM) extraction fields, especially for short-distance gassy multiple-seams. Research has proved that the most effective way to increase coal seam permeability is to decrease the ground stress. Protective seam mining technology is a surrounding rock control technology, which can effectively reduce the ground stress and increase the permeability of the protected coal seam. In this paper, we try to use upper protective seam mining technology to simultaneously extract coal and gas. Findings are based on a FLAC3D simulation of stress variation during the mining of the No. 12 coal seam in the Daxing coal mine, Tiefa Coalfield, China. Results indicate that, after mining the upper protective seam, the pressure-relief effects of the rock mass generated three belts and five zones below the protective seam, providing the space and time for gas pre-extraction engineering. Within the protected area, the numerical simulation indicates that the stress of the No. 13/14 coal seam reduces 95.84% and 88.25% respectively, while the expansion deformation of the protective seams reach 6.87 ‰ and 6.70 ‰ respectively, which demonstrate that the protective mining technology can provide a significant pressure-relief effect to the outburst-prone coal seam. Combining stress relief in this manner with pressure-relief from engineered gas drainage (performed by crossing boreholes from the floor rock roadway) applied before the mining of the protective seam, it would not only be beneficial to CBM drainage but also can reduce the gas outburst risk of the protected seams.INTRODUCTION Internationally, since France used protective seam mining technology to control coal and gas outburst in 1939, it has been promoted and applied in many countries (?????, 1966). Since 1958, China has taken the mining test and engineering practice of protective seam mining technology in the Beipiao, Tianfu, Nantong, Zhongliangshan, Songzao, Huainan, Huaibei, and other coalfields (Yu, 1992). Long-term theoretical research and mining practice of outbursts and dangerous coal seams show that protective seam mining technology is the most effective, safest, and most economical outburst prevention measure (Cheng, Fu, and Yu, 2009; Hu et al., 2008; Cheng and Yu, 2007). Under the condition of high gas content coal seams, the safety and efficiency of simultaneous extraction of coal and gas can be realized through a reasonable mining sequence and an effective gas extraction method (Cheng and Yu, 2003). The in situ stress distribution of the protective seam (No. 1 coal seam) and protected seam (No. 2 coal seam) during protective seam mining in the Haishiwan coalfield formation (Figure 1) (Li et al., 2014). A comparison of the stress and displacement (five zones and three belts) of the rock mass below the protective seam, and in a multiple-seam context in the Dalong Mine, is shown in Figure 2 (Jiang et al., 2015). After mining protection coal in a close-distance seam group, the small spacing between the coal seams causes the protective coal and the protected coal between part of the rock to crack through each other until the protective layer of gob is through the area. This provides a desorption of gas to the protective layer of the mining space channel, making the coal seam permeability increase to several hundred times and improving the gas discharge capacity (Zhai, 2008)."

Jan 1, 2017

A PRELIMINARY PROGRAM, dated April 25, 1974, was prepared for Development Engineering, Incorporated (DEI) on research and development laboratory, field and other engineering studies for the disposal of retorted oil-shale materials. This PRELIMINARY PROGRAM included a discussion on the peculiarities of the retorted shale materials to be investigated and a discussion of the various laboratory and field tests which would need to be conducted to define their physical and chemical properties. The PRELIMINARY PROGRAM was divided into eight work phases as follows: I -- Program Development II -- Exploratory laboratory tests on old USBM retorted shale III -- Laboratory tests on pilot plant retorted shale. IV -- Laboratory tests on retorted shale from the semi-works plant and field test plots and ponds. V -- Field compaction tests. VI -- Infiltration pond tests VII -- Bureau of Mines special tests.

Jan 1, 1975

By Raja V. Ramani

In many instances, the actual production from a longwall face does not equal the planned capacity. General problem areas which have been identified include face length and panel depth, face area and gate entry roof support, face conveyor and shearer wear, outby haulage system failures, number of entries in longwall gate development and longwall move time. The performance of a longwall face is totally dependent on the interaction of these and many other factors. To explore fully these interactions, a systems analysis of longwalls has been performed. In this paper, the systems approach, the factors considered in the analysis, and the results of the analysis are presented.

Jan 1, 1983

By A. Y. Lee

Prior work at the Bureau of Mines resulted in the successful development of a bench-scale, combination electrorefining-electrowinning method for recycling the lead from scrap batteries using waste fluosilicic acid (H2SiF6) as electrolyte. This paper describes larger scale experiments. Anodes cast from scrap battery lead were electrorefined in a 20-L multielectrode cell for 3 to 7 days. The anodes, containing 2 to 2.5 pct antimony, were ideal for obtaining firm and adherent slime blankets. Cathode deposits, assaying 99.99 pct Pb, were obtained, with current efficiencies near 99 pct. Sludge leaching was done in 100-L tanks followed by filtering in 61 cm square vacuum pan filtersu Lead of greater than 99.99-pct purity was recovered from the filtrate by electrowinning in a 20-L multielectrode cell using insoluble Pb02-Ti (lead dioxide-coated titanium) anodes and pure lead cathodes. The fluo-silicic acid electrolyte depleted in lead was repeatedly recycled to leach more sludge, and there was no problem with impurity buildup. The amount of Pb02 formed on the anodes during electrowinning was less than 1 pct of the total lead deposited on the cathodes, as long as the phosphorus concentration in the electrolyte was greater than 1.3 giL. Emissions of lead in air were less than 10 ~g/m3, well below the proposed OSHA limit of 50 ~g/m3.

Jan 1, 1984

By L. A. Nazarova, M. Vandamme, L. A. Nazarov, R. I. Rodin

"The paper describes a new method of interpreting the “canister test” data for the quantitative estimation of gas-kinetic parameters of coal bed based on the developed model of gas emission from coal sample placed in a sealed container. The model accounts for grain-size composition of the sample, initial gas content S, as well as coefficients of diffusion D and mass transfer ?. The inverse coefficient problem is formulated to find S, D and ??from the data of pressure measurements in the sealed container. It is shown that the inverse problem is uniquely solvable if the pressure is dropped during the experiment. The method has been tested using the data from an underground coal mine in the Kuznetsk Basin.Based on the poroelastic model of a coal bed and Khristianovich’s concept about origination and evolution of the filtration zone F in the neighborhood of a degassing borehole the authors considered the corresponding direct problem on rock mass geomechanical state. It was offered interpretation method for data on pressure measurements in a plugged degassing borehole allows evaluation of the diffusion coefficient, the horizontal component of natural stress field and parameters of F. The related inverse problem of the mixed type is formulated, and the cost function is constructed. The analysis using synthetic input data has shown that the cost function has a number of local minimums arranged on the same straight line, one of the minimums being the inverse problem solution. INTRODUCTIONPre-mine degassing is an integral part of coal mining. It allows mitigation of induced accidents in mines (coal and gas outbursts, rock bursts) (Guide, 1990; Malyshev & Airuni, 1999; Seidle, 2011) and also furnishes an alternative and ecology-friendly energy source—methane (Rice, 1997; Nambo, 2001). Choosing an optimized pattern of degassing boreholes, as well as estimating degassing time and amount of gas recovered requires data on gas-kinetics indices of coal beds out of which the key parameter is a gas content S. According to the latest guidelines for coal mines in Russia (Ruban et al, 2012), mining is allowed if S in a coal bed section is under 7 kg/m3."

Jan 1, 2015

By Donald R. Williamson

Statistical studies at Cyprus Pima Mine indicate that samples from 22 blastholes are necessary for determining average copper grades, within a desired range of precision, for mine-model blocks by arithmetic averaging. The average number of holes in such blocks is 14. Many considerations show that more holes will not be drilled for sampling. A way to determine block grades more reliably than by" arithmetic averaging was sought. Thus far arithmetic averaging has proven to be the best procedure for the particular operation characteristics despite the small number of samples. It naturally follows that expenditure of great effort in sampling blasthole cuttings is unwise.

Jan 1, 1977

By Louis R. Bernier

Since 1978, most systematic studies of AMD passive treatment with limestone drains (LD) have dealt with coal mines in the United States. The authors present in this paper the first results of a triennial study initiated in 1999 on the performance of LD installed at the Ni-Cu Lorraine old mine site in Temiscamingue during a remediation plan that involved the installation of a cover with capillary barrier effects (CCBE) over the reactive pyrrhotite-rich tailings. Typically, a LD is a trench enclosed by impervious materials filled with crushed limestone and may be oxic or anoxic. Four LD (one filled with marble and 3 with dolomite) were installed at the Lorraine site. The LD have been in operation since May 1999 and are performing differently. The most contaminated mine effluent flows south and is directed towards 3 LD filled with crushed dolomite, while a 4th LD was filled with crushed marble and installed west. The LD filled with marble has been generating maximum alkalinity since the beginning of the passive treatment. Two of the dolomite drains have been generating alkalinity since mid-summer 1999, but one is not, even if a substantial pH raise was observed. A pH above 5.5 is required usually for the dolomite drains to start generating alkalinity. The installation of LD at the Lorraine site contributes significantly to the reduction of metals and sulphates loading.

May 1, 2001

By Marcos Fernando Campioto Junior

O objetivo deste trabalho é apresentar os resultados obtidos, após a implantação da ferramenta de otimização do planejamento e programação da produção CScheduler Weekly Planner da PSI Metals na ArcelorMittal Tubarão. A ferramenta de otimização CScheduler permite realizar o planejamento e programação de médio prazo para as máquinas de lingotamento contínuo da ArcelorMittal Tubarão, visando melhor atendimento as regras de negócio relacionadas a cliente, redução custos operacionais e redução de instabilidade operacional do processo. Este trabalho também apresenta a criação de um novo Modus Operandi para o planejamento e programação com resultados obtidos em casos de testes e resultados pós-implantação em produção.

Oct 30, 2017

By Vinicius Alves Gomes, Jean Igor Margem, Thallis Cordeiro, Frederico Muylaert Margem, Roberto Faria Jr., Sergio Neves Monteiro, Marina Rangel Margem

Natural fibers are attracting the interest of engineering sectors owing to specific advantages such as lightweight and lower cost as well as for their inherent condition of being renewable, biodegradable, recyclable and neutral with respect to CO2 emission. In particular, the fiber extracted from the malva plant stem is nowadays recognized as one of the strongest lignocellulosic fibers. However, the thermal properties of the malva fibers have yet not been fully investigated. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity of a pressed malva fibers sample. The results revealed that these fibers showed a superior thermal insulation capacity.

Jan 1, 2015

By V. B. Telles, J. A. S. Tenorio, J. O. Alves, D. C. R. Espinosa

"The world production of crude steel in 2009 reached 1.2 billion tons. For each ton of steel produced, 150 kg of steelmaking slag and 20 kg of steelmaking dust are generated. These are wastes with considerable production and limited applications, therefore this work studied the recovery of these wastes into useful sub-products. The slag was used as raw material in the production of rock wool (a thermo-acoustic insulator) and the dust was inserted in the iron ore sintering process. Results showed that produced materials have exceptional proprieties, therefore the recovery of these wastes can contribute to decrease extraction of non-renewable resources, reduce the costs and impact of disposals, and aggregate value to the slag and dust.1. IntroductionSteel production using Eletric Arc Furnace (EAF) has grown over 119 million tones in the last years. In 2008 30.7% of all steel produced, was obtained through EAF. In United States of America (USA) the percentage of this process in the production of steel was about 58% in 2008, while in 2000 this percentage was only 47% [1]."

Jan 1, 2011

By A. C. Smith

The U.S. Bureau of Mines developed an experimental method to evaluate the relative effectiveness of water additives on the extinguishment of coal fires. The experiments were conducted in the fire zone of the multiple-entry section of the Bureau's Bruceton Experimental Mine. Four-hundred-pound Pittsburgh Seam coalbeds were ignited and allowed to burn until well-developed fires were achieved. Extinguishing agent-water solutions were then applied to the fires, and the quantity required to extinguish the fires was compared with the quantity of water alone required to extinguish similar fires. A 20% diammonium phosphate-water solution required an average of 5.8 gal to extinguish the coal fires, while two commercially available additive-water solutions required an average of 8.1 and 8.0 gal, respectively. The average amount of water required to extinguish the fires was 7.4 gal. An analysis of covariance, using the thermal energy of the coalbed to quantify the fire at the time of extinguishment, showed that the diammonium phosphate-water solution was slightly more effective at extinguishing these coal fires than water alone, and the two commercially available additive-water solutions were statistically equivalent to water alone.

Jan 1, 2010

By John R. FitzPatrick

The separation and purification of uranium from either nitric acid or hydrochloric acid media tan be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-exchange as a method for extraction/purification of uranium from acidic media. In addition, waste stream polishing is associated with this effort in order to achieve more complete removal of the uranium prior to recycle of the acid. Extraction chromatography has been demonstrated' to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps. We will discuss contact experiments for evaluation of eleven different resins for uranium removal from nitric acid, the evaluation (again by contact experiments) of uranium elution from the ion-exchange media by various chemicals, and small-scale experiments for the removal of 235U from nitric acid. Larger-scale (100-gram) flow experiments using depleted uranium, were done after the small-scale evaluation Of the selected resin. A discussion is also included concerning the shortcomings of the contact experiments and how the flow experiments were modified in order to overcome these problems. We will also discuss the application of ion-exchange for some specific process needs at Los Alamos Contact experiments were used to evaluate some commercially available solvent-impregnated resins in addition to evaluation of several resins of this type synthesized in our laboratory. These experiments' involved both nitric and hydrochloric acid media. The data from these experiments will be used to determine the column size and' amount of resin required to polish the waste stream produced by the ion-exchange process described above. Small-scale flow experiments will be described and data given on the mass balances achieved using this two step process. Future work for evaluation of new ion-exchange and solvent-impregnated resins as well as the search for new eluants will be discussed. Other future experiments for both processes, including large-scale experiments, will be discussed in detail.

Jan 1, 1996

Major activities of the Bureau of Mines Explosives Research Center during fiscal year 1965 (July 1, 1964, to June 30, 1965) are reviewed briefly. Part 1 summarizes significant accomplishments of the projects that were active during the report period. Part 2 presents short abstracts of the publications that appeared in the Bureau series and in other media during fiscal year 1965. Publications issued after June 30, 1965 are noted where pertinent in footnotes but are not abstracted. ACKNOWLEDGMENTS The Bureau of Mines gratefully acknowledges the support given through cooperative agreements by the following organizations to investigations con¬ducted by the Explosives Research Center during fiscal year 1965: Dow Chemical Company Manufacturing Chemists' Association Monsanto Chemical Company The Sulphur Institute

Jan 1, 1966

By Rokot M

In a little over three years, Chevron Niugini has built up a team of relatively young, hard working men and women, mostly Papua New Guineans, who spend most of their working days out among people in the Southern Highlands and Gulf Provinces who are directly affected by the Kutubu Petroleum Development Project. These are Land and Community Relations officers, or LACROs. They take on a huge responsibility, not only representing Chevron but also being friend, advisor and negotiator, frequently dispensers of medicines, and agricultural advice and more. When things go well, others get the praise, when things go wrong, LACROs are the martyrs. Just as the geologists who locate the oil, the drillers who find it, the engineers who design the facilities, the construction gangs who build them, the landowners who claim it, and the Government who monitor it, so are the LACROs part of a team.

Jan 1, 1991

By Olívia Cristina Petriz Monteiro

A Companhia Siderúrgica Nacional (CSN) possui uma Oficina de Manutenção Mecânica Central que fornece serviços de reparo, fabricação e manutenção de conjuntos mecânicos e componentes. A usinagem é um dos setores de maior demanda durante o reparo na Oficina e é considerada o grande gargalo entre as etapas de reparo/fabricação. Na busca por uma melhora na qualidade do atendimento e dos serviços prestados, o trabalho teve como objetivo identificar e implementar um novo sistema de medição para o Controle de Qualidade da Oficina Mecânica, reduzindo a demanda de inspeções dimensionais e geométricas para o setor de Usinagem. Com a compra dos instrumentos de medição tridimensional, o Laser Tracker e o Braço de Medição, foi possível aumentar a disponibilidade da usinagem, diminuir o tempo de inspeção de peças, acelerar o processo de decisão dos reparos, reduzir o tempo de entrega dos equipamentos, aumentar a confiabilidade das inspeções, além de e efetuar eventuais serviços de medição em campo.

Aug 8, 2018

By William C. Miller

This report describes investigations by the Bureau of Mines designed to establish the noise level and spectrum of various types of pneumatic rock drills and to furnish information that would be useful in conducting sound measurements in mining environments and in reducing the noise generated in pneumatic drilling. These investigations show that (1) the noise generated by the drills in the frequencies below 100 cps is caused by the impact of the piston and drill steel, in the frequency range between 100 and 2,000 cps by the exhausting of air from the ports, and in the frequencies above 2,000 cps by the resonant frequencies of steel drill parts and of drill steel; (2) satisfactory instruments and instrumentation systems are available for field and laboratory measurements; (3) reliable sound measurements can be made in mining environments; and (4) devices can be developed that will abate the noise.

Jan 1, 1963

The effect of the acid anion on chalcopyrite (CuFeS2) leaching has been examined, under care-fully controlled conditions, in a range of acids in stirred reactors and columns at pH 1. Solution speciation calculations were performed to determine possible rate controlling species. The relative leach rates of Cu from chalcopyrite can be explained quantitatively entirely on the basis of solution speciation without the need to invoke any rational relating to surface structure/speciation. The rate of Cu release is first order with respect to Fe3+ activity. The stirred batch reactor experiments at fixed pH 1, Eh of 750 mV (SHE) and 75? showed that chalcopyrite leach rates were rapid in both HClO4 and H2SO4 with 100 % Cu recovery after 73h and 97 h respectively. However, the leach rate in H2SO4 was slower as compared to the HClO4 leach due to a slower increase in the activity of Fe3+ due to the formation of FeSO4-. The presence of Cl- in the leaches (HCl and H2SO4 with NaCl added) led to a low activity of Fe3+, due to the high activity of FeCl2+, resulting in very low leach rates. For the column leach experiments dissolution of Fe and Cu from the pH 1 HCl eluted chalcopy-rite column with quartz proceeded at several times the rate of any other column (chalcopyrite with and without quartz and/or pyrite leached with H2SO4, HClO4, HCl). Three observations indicate that galvanic interactions are not leach rate controlling role: a) The rate of leaching was not uniformly increased for the non-quartz containing columns where the two sulfide minerals, chalcopyrite and pyrite, are in physical contact as compared to the analogous quartz containing columns where they are not; b) there exists a reasonable correlation between the rate of Cu release and the effluent Fe3+ activity for all columns thus indicating that the leach rate is determined by solution speciation; and c) in all cases the proportion of Fe to Cu leached indicates preferential dissolution of Cu over Fe. However, the proportion of Fe to Cu is either the same or greater than expected on the basis of the single mineral columns. This indicates that chalcopyrite is not dissolving preferentially to pyrite.

Jan 1, 2014

By Izabelle Lannes Salgueiro Ferreira

O presente trabalho teve como objetivo garantir a estabilidade no processo de conformação mecânica das barras redondas laminadas, visando reduzir a geração de produtos não conformes e o número de reclamações de clientes pelo motivo de ovalização. As barras redondas laminadas são utilizadas nas indústrias de trefilação, metal mecânico, agroindústria e em outros componentes industriais. A metodologia utilizada neste trabalho foi DMAIC, (definir, medir, analisar, melhorar e controlar). Esta ferramenta é utilizada para melhoria de processos. Através desta ferramenta foi possível identificar os parâmetros mais influentes na geração de defeitos por ovalização, o que possibilitou a elaboração de um plano de ação direcionado às causas raízes. Após a conclusão do plano de ação, houve redução de 36% em média na geração de produtos não conformes e nenhuma reclamação de cliente foi recebida até o mês de março de 2016, além de uma maior estabilidade do processo durante a laminação deste produto.

Aug 17, 2017

By J. A. Organiscak

The U.S. Bureau of Mines investigated the relationship of bituminous coal seam parameters and the amount of airborne respirable dust generated at longwalls. Dust and coal samples were obtained from 20 longwalls operating in geographically representative coalfields throughout the United States. Statistical analyses of coal seam parameters and airborne respirable dust measurements indicate a likely causal relationship between seam type and respirable dust. Low-ash, high-volatile coal seams were associated with higher airborne respirable dust levels. A negative linear correlation (significant at the 95-pct confidence level) was observed between the seam's ash content and airborne respirable dust, explaining up to 18 pct (R2 = 0.18) of headgate dust level variation and up to 15 pct of tailgate dust level variation. Volatile matter was found to have a positive linear correlation with tailgate dust level, explaining 16 pct of the variation. Further data examination indicates that these relationships with dust are most likely nonlinear, because of improved R2 values over the linear correlations. However, a notable portion of longwall dust production is influenced by other operational parameters, so additional research under more controlled conditions is needed to determine the seam's causative functions.

Jan 1, 2010

By T. R. Kostecki, A. J. S. Spearing, A. Hyett, M. Gadde

Ground control research for underground coal mining has progressed significantly over the past several decades. With this progression, and the ability to analyze and model underground conditions, underground working conditions have significantly improved. In order to progress further, the behavior of roof support must be known and be adequately modeled, such that models can be used for support design under different geological and mining conditions. This paper discusses the results from a research project funded by the U.S. National Institute for Occupational Safety and Health (NIOSH) and undertaken by Southern Illinois University Carbondale and Peabody Energy. The research involved installation of active and passive instrumented bolts in mines, recording relevant in situ data and then attempting to model the behavior of the bolts as mining progressed. Such calibrated models could aid in design of roof supports under different geological and mining layouts and thus, hopefully, further improve rock related safety.

Jan 1, 2012