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By Christopher Mark, Gregory M. Molinda, Timothy M. Barton

The Coal Mine Roof Rating (CMRR) was first presented at this Conference nine years ago. Since its introduction, the CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, and extended cut evaluation. It has also become truly international, with involvement in mine designs and funded research projects in South Africa, Canada, and Australia. The purpose of this paper is to bring the mining community up to date with recent improvements and applications of the CMRR. The most important new development is a streamlined process for determining the CMRR from exploratory drill core. Just three types of information are now required: •Fracture spacing (or RQD) •Uniaxial compressive strength (or axial Point Load Testing) •Diametral Point Load Testing The moisture sensitivity adjustment has also been changed, and new research has related the immersion test to slake durability. Most recently, the CMRR has been implemented in a computer program, which can be obtained from NIOSH free of charge. The program facilitates calculation of the CMRR from either underground or drill core data. Values from many locations can be saved in a single file, and an interface with Autocad allows CMRR contour plots to be integrated into mine planning.

By Giancarlo Obando Díaz

Ante la irregular distribución de la riqueza y consecuente subdesarrollo socioeconómico de algunos centros poblados del Perú, se estableció que el uso del gas como fuente de energía renovable puede satisfacer la demanda de los sectores desfavorecidos con la disponibilidad comercial. En ese sentido, el presente texto señala las herramientas posiblemente utilizadas por empresas mineras para aprovechar el potencial energético del biogas y la calidad fertilizante del efluente en el desarrollo socioeconómico de comunidades rurales aledañas a sus centros de operaciones.

Sep 14, 2009

The relationship between neural network (NN) performance and the parameters that form the architecture of the neural network is complicated. This paper studies an issue that is still controversial—the effect of the number of neurons and number of hidden layers on NN performance. This paper tests if the above parameters affect network performance when the NN is trained according to the quick stop strategy. It was determined that the number of neurons did not have any effect on the NN performance for a single layer or a double layer network. It was also found that the training error and calibration error could be poor indicators of the prediction correlation coefficient.

Jan 1, 2003

By Jean-François Lapointe

Many advances have been made concerning the automation of heavy equipment teleoperators such as those found in mining. Complete automation, however, is not achieved yet and the operation of these vehicles still relies on the presence of a human operator. Fortunately, a lot of research has been done in order to improve the performance of these human-machine systems. This paper presents the characteristics of different control modes and input devices used for the control interface of those telemanipulators. We describe the benefits and drawbacks of each particular control interface on the overall system performance, based on a review of research in the field. We conclude with some recommendations and a discussion of future research needs, given the new potential advances offered by virtual environment technology and embedded computing.

May 1, 2001

By Brian W. Stump

"Seismic waves from explosions can be used to characterize physical processes in and around the source. The quantification of absolute levels of ground motion is important for minimizing impact on nearby people and structures. We contrast work in characterizing seismic radiation from contained nuclear explosions with ground motions from multiple explosion quarry blasts. A physical basedunderstanding of the explosion source function allows prediction and extrapolation to new environments where experimental data may not exist."

Jan 1, 1990

Several glacial episodes have been distinguished in the Shotover Valley. These produced fluvioglacial aggradational deposits downvalley from the terminii, commonly with well-preserved terrace treads, as exemplified near Skippers. Chronological links can be determined between the Shotover tills and sediments and assessed equivalent deposits in the Wakatipu Basin/Kawarau Valley region through axial valley profiling. Constructed relationships suggest older Shotover events were probably large and left little detrital deposits within the valley. In contrast, the younger advances were smaller and valley-constrained. They are modelled as being wholly of Waimea or Otira Glaciation age, advances from the latter period producing the visually distinctive flights of terraceremnants. Both the terraces and the inner gorge, now occupied by the Shotover River, have been extensively worked for alluvial gold. Enrichments in the former environment have predominantly been as bottom or intermediate lags produced during degradation phases of catchment erosion. Surface lags have been locally targeted. Placer mining in terrace areas involved both tunnelling and sluicing techniques. In the modem river the greatest concentrations were on the schist or false bottoms, although flood gold has always contributed to the returns. Placer mining techniques here were highly variable.

Jan 1, 1998

By T. J. Goff

Keywords: accurate control, matte level, smelting operations, process control, tapping, sounding bar, electromagnetic measurement [ ] Accurate control of matte levels during primary matte smelting operations is desirable in order to improve process decision-making. High matte levels in the vessel could have to disastrous consequences, particularly in the new generation of intensive smelting furnace with deep-cooled copper coolers. Knowing when to commence tapping and a better understanding of melt times can only be improved if the furnace levels are monitored correctly. At Lonmin Marikana Smelter Division it has long been understood that the matte level information being provided by the manual sounding bar is only as good as the operators? following of measurement procedure, their skill in assessing what the sounding bar is displaying, and their individual interpretation of what they are looking at. This paper sets out to show how this problem was identified as an area of major concern to the plant, how a solution was sought and how an electromagnetic measurement system was installed as an alternative measurement to the matte sounding bar system. Other areas discussed in the paper are the difficulties to be overcome when first installing new equipment and how these teething problems were solved by close co-operation between Lonmin and equipment suppliers, which led to some design modifications to the delivery system. In conclusion the paper discusses the results between the electromagnetic measurement and the manual sounding measurement and how best to integrate the generated data into the plant?s process control system for improved decision making.

Jan 1, 2011

By Anja Pfennig, Axel Kranzmann, Sabrina Schulze

The CCS technique involves the compression of emission gasses in deep geological layers. To guarantee the safety of the site, C02-corrosion of the injection pipe steels has to be given special attention when engineering CCS-sites. To get to know the corrosion behaviour samples of the heat treated steel 1.7225 42CrMo4, used for casing, and the stainless injectionpipe steel 1.4034 X46Cr13 were kept at T=60 °C and ambient pressure as well as p=lOO bar for 700 h - 8000 h in a C02-saturated synthetic aquifer environment similar to possible geological on-shore CCS-sites in the northern German Basin. The isothermal corrosion behaviour obtained by mass gain of the steels in the gas phase, the liquid phase and the intermediate phase gives surface corrosion rates around 0.1 to 0.8 mm/year at ambient pressure and much lower about 0.02 to 0.2 mm/year at 100 bar where the C02 is in its supercritical state. Severe pit corrosion with pit heights around 4.5 mm are only located on the 42CrMo4 steel. Main phase of the continuous complicated multi-layered carbonate/oxide structure is siderite F eC03 in both types of steel.

Jan 1, 2013

By R. C. Ellman

Since successful industrial lignite-burning equipment was developed in 1925, the commercial use of lignite as a fuel for power plants has increased. It has proved an entirely satisfactory fuel for generating power and can be burned efficiently by various methods.4/ Equipment to fire pulverized lignite was installed and used successfully at the Trinidad Station of the Texas Power & Light Co. as early as 1926. The lignite was predried in steam-heated grid driers before pulverizing.5/ This method of firing was used later in the Comal Station of the San Antonio Public Service Commission.6/ Both stations, however, have since been converted to use other fuels. Units for pulverizing and drying lignite are relatively new in the lignite-consuming region of North Dakota. The air which sweeps the pulverizer and transports the pulverized product to the burners is preheated to dry the lignite during pulverization. The first unit was installed in 1948 in one of the two boiler units of the Crookston Station, Otter Tail Power Co., Crookston, Minn.7/ In 1951 the 30,000-kw. W. J. Neal Station, Central Power Electric Cooperative, Inc., Voltaire, N. Oak., was designed and constructed for firing pulverized lignite exclusively. It is the largest lignite-fired, power-generating station in North Dakota. The 44,000-kw. Lewis and Clark Station of the Montana-Dakota Utilities Co., Sidney, Mont., is fired by a similar pulverizing system. Operation of this plant was begun in October 1958. At Fergus Falls, Minn., the 53,500-kw. Hoot Lake Station of the Otter Tail Power Co., also using a pulverized lignite-firing system, began operating in September 1959.

Jan 1, 1961

By C. B. Kenahan

The Bureau of Mines is developing methods for reclaiming the metal and mineral values contained in municipal incinerator residues. This report describes the first phase of the research, in which reliable methods for sampling and analyzing municipal residues were established and the composition and characteristics of the residues were determined. Samples were obtained from a variety of grate-type furnaces and also from a rotary kiln furnace. The samples were processed on a batch basis and separated into their natural categories by a variety of methods including screening, magnetic separation, air separation techniques, and handpicking. The main components of the residues were determined to be metal and metal oxides, glass, and ash.

Jan 1, 1968

By Cathleen J. Webb, Arden D. Davis

The Homestake Gold Mine at Lead, South Dakota, has been proposed as the host site for the Deep Underground Science and Engineering Laboratory. The laboratory will house neutrino experiments in mine workings at the 7400-foot depth, as well as research in geomicrobiology, rock mechanics, and ground-water flow. Initial plans for the laboratory were developed in 2000 after Homestake Mining Company announced the closing of the underground gold mine. Homestake’s owner, Barrick Gold Corporation, had agreed to donate the mine for a laboratory if it could be protected from environmental liability. That initial agreement was delayed, and Barrick turned off the mine’s pumps in 2003, allowing lower levels of workings to begin to flood with water. In early 2004, the Governor of South Dakota signed an agreement with Barrick that would indemnify the company and eventually transfer ownership of the mine to a state laboratory authority. South Dakota’s governor also announced plans to ask the state legislature for funds to help in the initial construction of the laboratory. A consortium of scientists from several states is currently preparing a detailed laboratory proposal for the National Science Foundation.

Jan 1, 2005

By Frank B. Fulkerson

Aluminum production in the Pacific Northwest has a new potential for expansion and increased stability of operation. This new potential results from greater availability of power; lower freight rates on alumina and aluminum; good market prospects for the metal, including western aluminum market expansion following a decline in defense requirements in the 1950's; and possibility of developing bauxite deposits in the Pacific Basin as well as other mineral resources. INTRODUCTION This is a report of a special study by the Bureau of Mines of the primary aluminum industry of the Pacific Northwest. It outlines developments relative to the United States as a whole.

Jan 1, 1962

By Amauri Garcia, Noé Cheung, André dos Santos Barros, Clarissa Barros da Cruz

Embora a resistência ao desgaste seja geralmente a principal propriedade avaliada decorrente da adição de terceiros elementos em ligas Al-Sn, não somente os fenômenos tribológicos são responsáveis pela deterioração gradual das peças, mas também os fenômenos relacionados à corrosão. Dessa forma, o presente estudo objetiva analisar o efeito de características microestruturais formadas durante a solidificação transiente da liga Al-9%Sn-5%Zn na resistência à corrosão em solução 0,06M NaCl investigada por polarização potenciodinâmica e espectroscopia de impedância eletroquímica. Foi observada uma morfologia microestrutural caracterizada por dendritas da fase α-Al com concentrações de Zn tanto na matriz dendrítica quanto em regiões ricas em Sn localizadas nos contornos interdendríticos. A evolução dos espaçamentos dendríticos primários (λ1) também foi correlacionada com parâmetros térmicos de solidificação. Finalmente, constatou-se que a amostra com microestrutura mais grosseira, ou seja, λ1 = 89,6 μm, apresentou comparativamente menor densidade de corrente de corrosão e maior resistência à polarização.

Oct 1, 2019

By Wilbur I. Duvall

In a review of so 40 papers on damage to residential structures resulting from blasting, only 3 were found that present data on the observed amplitude and frequency of the vibration levels produced by blasting together with an observed degree of damage to a residential structure. The data from these three reports have been analyzed statistically to determine if one of the quantities, displacement, velocity, or acceleration, is more reliable than the others for estimating the degree of damage to a residential structure. From this analysis the conclusion is drawn that a given degree of damage to a structure is most closely related to the magnitude of the particle velocity of the wave motion passing thru the earth at the structure location. On the average, only minor damage it observed for peak particle velocities of 5.4 inches per second, and major damage is observed for peak particle velocities of 7.6 inches per second. When the spread of the data is taken into consideration, the following statement can be made: Wave motions that have a peak particle velocity in excess of 2 inches per second have a fair probability of producing some damage to structures, whereas wave motions that have a peak velocity less than 2 inches per second have a very low probability of causing any damage. Therefore, the recommendation is made that vibration levels in the vicinity of residential structures should be maintained below a peat particle velocity of 2 inches per second. The above criterion for safe blasting is considered to hold over a wide variety of soil and rock conditions because the original data were obtained for a wide range of soil and rock conditions and on various types of residential structures. INTRODUCTION Ever since explosives were discovered and developed for mining purposes, there has existed the problem of what effects the air and ground vibrations resulting from blasting have on structures of various types. This problem is

Jan 1, 1962

By M. Ge

Pattison Mine is a small sandstone mine located in Iowa. The sandstones produced by the mine are not common construction and aggregate materials. The stones are used to produce a special type of sand for hydraulic fracturing, a critical technique for recovering tight gas and shale gas. These sandstones are very different from the minerals and rocks which have been studied extensively in mining. On the one hand, they are brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, they are friable, possessing extremely low, and in most cases zero cohesion. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for the mine operators. In order to resolve these problems, a research program was set up by the mine and Missouri University of Science and Technology. This paper discusses the preliminary results of this investigation.

Jan 1, 2012

By John E. Kelley

A method for measuring the spark-shower radiance of metals when abraded on a grinding wheel was developed by the Bureau of Mines for evaluating the sparking tendency of metals. The radiance was measured in units of emissive power per solid angle per area of the detector. Over 100 metals were tested and rated relative to commercially pure iron. The metals tested included elemental metals, iron binary and ternary alloys, iron-carbon ternary alloys, commercial steels, nonferrous alloys, and a few hard-metal compounds. Some alloys were synthesized; others were obtained commercially. Alloys that possessed good strength properties were emphasized for selection. The results indicate that the spark-shower radiance of plain carbon steels and carbon alloy steels was greater than that of pure iron. Certain elements, particularly vanadium and chromium, reduced the sparking tendency of iron. Stainless steels and particularly nickel alloys displayed low spark-shower radiance. Some metallic elements had much lower radiance than iron; others, much greater. Plain carbon steels, heat treated to a variety of hardnesses, gave radiance values that generally increased with increasing hardness. The effect on sparking tendency of an increase in hardness of an alloy steel was studied. The sparking tendency increased with an increase in hardness to a maximum, then decreased with a further increase in hardness.

Jan 1, 1974

By Jim Steding

L.G. Barcus and Sons, Inc. recently completed a three-phase project for the expansion of Presbyterian Hospital in Albuquerque, New Mexico for McCarthy Construction Co., the Construction Manager for the project. It was a challenge that allowed Barcus to demonstrate many of it's strengths. Safety of people and property, restricted access, low headroom conditions, extensive planning to maintain hospital operations and a tight schedule were all key elements affecting the successful installation of the Augered Cast-In-Place Piles. Phase I began with installing and performing a 450-ton pile load test on an 18-inch diameter Augerpile 65 ft long. The load test was installed and performed directly in front of the Emergency Room entrance. Space was limited and the E.R. had to remain open with uninterrupted ambulance access. The results of the load test were outstanding. In fact the test pile performed so well that some of the job piles were shortened from 75 ft long to 65 ft long. [ ]

Jan 1, 2003

By Foluke Salgado de Assis

A fibra de juta é uma das fibras com grande potencial para ser aplicada como tecido reforçando compósitos poliméricos Este trabalho avaliou a resistência ao impacto para compósitos de matriz poliéster reforçado tecido de juta. Os corpos de prova foram fabricados com diferentes percentuais de tecido de juta: 0, 10, 20 e 30% em fração volumétrica. O tecido sido de juta foi embebedado com resina poliéster (estado líquido) e curado em temperatura ambiente durante 24 horas. As amostras foram ensaiadas utilizando o pêndulo impacto Izod and a superfície de fratura foi examinada utilizando o microscópio eletrônico de varredura. A resistência ao impacto Izod dos compósitos poliéster-juta cresceu de maneira linear com o aumento da quantidade de tecido de juta. Utilizando 30% de tecido de juta, foi possível obter 83,1 J/m enquanto o poliéster puro (0% de tecido) obteve 21,8 J/m. O bom desempenho do compósito poliéster-juta pode ser associado com a dificuldade de romper o compósito em virtude do tecido de juta, assim como, as trincas produzidas através da interface poliéster/tecido de juta que colaborou com o aumento na absorção de energia durante o ensaio de impacto Izod.

Oct 30, 2017

By Detlef Ehlert

In view of the increasing level of cost pressure on the part of plant owners, optimized plant operation with top product quality and maintenance costs is indispensable. Unscheduled shutdowns with increased repair costs and production downtimes are significantly reduced by preventive maintenance and the stock-keeping of spare parts. To remain competitive in the steel market, it is important for plants owners to operate their plants with the highest possible degree of energy efficiency and at high availability in order to manufacture high-quality products. Plant Monitoring Systems make it possible to optimize the manner of production. An integrated overview of the overall process, under consideration of process stability, product quality, production costs and plant availability ensures a “transparent plant”.

Aug 16, 2017

By Harry Perry

One of the most notable achievements of the iron and steel industry in the United States in this century has been the general increase in productivity of individual blast furnaces and the reduction in coke rate. Most of the improvement in furnace operations has occurred within the past decade. During this time the output of the average furnace increased about one-third, while fuel rates decreased from 15 to 20 percent. For example, in 1949, the iron and steel industry produced 811.2 short tons of pig iron per blast-furnace day with a coke rate of 1,870.4 pounds per ton of pig iron, By 1960, the average production of pig iron per blast-furnace day had risen to 1,182.4 tons, while the coke rate had decreased to 1,497 pounds per ton of pig iron. These figures are averages for the entire industry; many furnaces produced over 2,000 tons per day and one furnace, operating on pellets, reached 2,700 tons of pig iron per day, Coke rates of individual furnaces varied, but some furnaces operated on less than 1,200 pounds per ton of pig iron. The significance of this decrease in coke rate is shown clearly when data on pig-iron production and coke consumption in 1959 are compared with 1948. In 1948, 57.3 million short tons of coke was charged into blast furnaces to produce 60.1 million tons of pig iron; in 1959 only 47.6 million tons of coke was needed to produce 60.2 million tons of pig iron. Thus, in 1959, nearly 10 million tons less coke was required to produce about the same amount of pig iron as was produced in 1948.

Jan 1, 1962