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By R. D. Joseph

This report deals exclusively with roof-fall accidents that occurred during 1955 and 1956 in both anthracite and bituminous-coal mines throughout the United States. The report stems from a cooperative study conducted by the Bureau of Mines and the Roof-Control Committee of the Coal-Mining Section, National Safety Council. The study includes an analysis of individual accident reports, sets forth the measurable factors, and compares such factors with a representative sample of average data from 39 anthracite mines and 117 bituminous mines (appendixes A and B). Particular emphasis is placed on fatal roof-fall accidents with respect to their causes, locations, and the methods of support used at the point of occurrence. INTRODUCTION The purpose of the report is to classify all measurable details of the occurrences of roof-fall fatalities so that the material presented will assist those promoting safety and will serve as a manual for those whose principal duty is inspection of mines.

Jan 1, 1958

By A. Karadogan, G. Tuncer, A. Kahriman, S. Gorgun

This paper presents the results of ground vibration measurements induced by blasting operations at five different sites located close to the residential areas. Within the scope of this study, ground vibration components were measured for all blast events over a long period of time in order to predict peak particle velocity and determine the slope of the attenuation curve for five sites. During the study, while the parameters of scaled distance were being recorded carefully, suitable monitors for all blast events of five blasting sites measured the ground vibration components. At the end of evaluation of the data pairs, an empirical relation, which gives an average line at 95% confidence level, and upper bound 95% prediction line with a good correlation coefficient was established and suggested for each site

Jan 1, 2003

By H. Maleki, G. Tetreault

This study was initiated by the Bureau of Land Management (BLM) to develop guidelines for determining the maximum economic recovery of resources in coal mines. The work was in response to a requirement in the Mineral Leasing Act of 1920 and Federal regulations. The intent was to address the economic rainability of small, irregular reserves in existing longwall mines. In particular, there was a need to determine if room-and-pillar mining using a continuous miner (CM method) was economically sound, or whether unconventional (short or odd-shaped) longwalls could be used to recover small coal reserves economically. Small reserves, called "widgets" are left in longwall mines on one side of the mains, near outcrops and adverse geological conditions, or near any other location where reserve geometry does not lend itself to mining with a rectangular longwall panel. The work included (1) analysis of the geologic, geo-technical, and economic factors that influence the recovery of small coal reserves, (2) analysis of historic changes in supply, demand, and coal prices, (3) development of typical cost models for room-and-pillar and longwall mines, and (4) development of a practical methodology for determining maximum economic recovery. The methodology included an evaluation of the ratio of coal mined during longwall mining to that mined for development (LDR) as well as costs of maintaining coal quality depending on market conditions. The LDR is a good indicator of mine efficiency and overall coal recovery in modem longwall mines and thus is used to evaluate the

Jan 1, 2001

By C. A. C. Sequeira, G. N. Anastassakis

Electrochemical processes occur on nano-, micro- and macro- scale in numerous applications such as fuel cells, batteries, hydrogen production, mineral extraction, water treatment, electrotherapy, sensors and many others. In most of these applications, gases evolve either at one or both electrodes due to electrolysis. These gases form bubbles play a crucial role in electrochemical systems. For example, in electrowinning (EW) that is used to extract and refine metals such as Cu, Zn, Ni, Mn, and Cd from their solutions, in most cases the solution is acidic and oxidation of water molecules at the anode is the common counter reaction, which results in the liberation of oxygen bubbles. This generally requires a high overpotential and accounts for a considerable percentage of the energy consumed in metal EW electrolytic cells, apart from producing acid mist that is very corrosive for other cell equipment and building structures. The behaviour of bubbles in electrochemical systems is still a complex challenging topic which requires a better understanding of gas bubbles hydrodynamics and their interactions with electrode surface and bulk liquid, as well as between the bubbles themselves. The objective of the current paper is to briefly review the fundamental hydrodynamics of both gas bubbles on the electrode surface and gas bubbles interaction with the liquid bulk solution. The current work also investigates the impact of gas bubbling and some operating parameters in copper EW, such as current density (100-500 A/m2), temperature (25-75ºC), acidity (50-300 g/L) and a typical chemical mist suppressant (<50 ppm). The results clearly show that both suppressant and temperature reduced the overall surface tension of the solution. Also, chloride concentration and applied current improved electrolyte flow and copper quality at higher current densities. The current paper contributes to the development of mineral processing (specifically to copper hydrometallurgy), as it deals with fundamental hydrodynamics and interactions of gas bubbles that formed during copper EW and play a crucial role in copper electrochemical systems.

Jan 1, 2018

By Alain Dorval

"''Purification of marine sands from Les Iles-de-la-Madeleine''This paper presents the results of the work that has been done at CRM pilot plant for «Les Silices du Golfe Inc.». Essentially the purpose of this piloting was to demonstrate, on a semi-industrial scale, the process of purification of marine sands from Les Iles-de-la-Madeleine; that had been developed by CRM Process Development Service. This purification is necessary to produce silica suitable for the glass sand and the foundry sand markets.Introduction«Les Silices du Golfe Inc.» is a company who intends to dredge marine sands around the «Les Iles-de-la-Madeleine» coasts. The material will be transported to Gaspesia where electricity, water supply, and a convenient site is available to treat it. A high purity silica intended for glass sand and foundry sand markets will be produced. The objectives of this purification process are to remove organics, calcium, feldspars and iron.Material ReceivedCRM received 50 tons of sand with Si02 varying between 80,6 and 99,3 % (see Figure.1). The highest variations in impurities were the calcium and lost on ignition. We notice direct relation between% SiO2, % CaO and % L.O.I. as you can see on the following Figures 2, 3 and 4."

Jan 1, 1994

By J. A. Organiscak

This paper examines methods for limiting occupational silica exposures for roof bolting personnel in underground coal mining. A canopy air curtain and an air tube were evaluated as means to provide filtered air over the breathing zone of these personnel. Laboratory testing showed that dust reductions beneath the air curtain and air tube approached 60 percent and 40 percent, respectively, with low interference air velocities. The data also showed that dust reductions were highest for positions closest to the device and that these levels decreased with distance. This paper also evaluates a metal rake, a flexible insert, and a rigid insert for cleaning the roof bolter dust collector box. Less dust was produced when using the rigid insert. Surprisingly, the flexible insert was sometimes no better than scraping or raking the dust onto the mine floor. However, little dust got on the coveralls when using either of the inserts.

By Daniel H. Isreal

Because the federal government owns and controls nearly 80% of the most valuable oil shale reserves in the West, it is inevitable that federal leasing and siting will play a prominent role in development of an oil shale industry during the 1980s. Also, because of recent enactment of the Synthetic Fuels Corp. authorizing up to $88 billion in loan and price guarantees-federal financing will provide the critical incentive to permit private investment in a still infant industry.

Jan 1, 1981

By Carl H. Beal

The oil industry in the United States is further advanced than in any other country, because of American initiative and the development of industries dependent in some way on petroleum or its products. For this reason the output has constantly increased (fig. 1), and as a result this country has produced more than half of the total output of the world. Trw total past output of the world is approximately 7,000,000,000 barrels of 42 gallons each; of this the United States produced about 4,000,000,000 barrels, or about 57 per cent. The limit of production in this country is being approached, however, and although new fields undoubtedly await discovery, the yearly outpnt must inevitably decline, because the maintenance of a given output each year necessitates the drilling of an increasing number of wells. Such an increase becomes impossible after a certain point is reached, not only because of a lack of acreage to be drilled, but because of the great number of wells that will ultimately have to be drilled. According to figure 1, the daily production per well each year has increased during the last few years. However, this increase is abnormal, being caused by the new pools brought in. Although such a condition may continue for several years, the average production per well will finally begin to decrease on account of the lack of new pools to make up for the normal decline in production of the old ones.

Jan 1, 1919

By M. N. Chandraprabha

This paper discusses the role of mineral-adapted acidiphilic microorganism Acidithiobacillus ferrooxidans on the beneficiation of arsenopyrite containing multisulfides (pyrite and chalcopyrite). Adaptation to minerals altered the surface properties of the microorganism. Bacterial adaptation to arsenopyrite and controlled bacterial adhesion to mineral surfaces lead to selectivity in arsenopyrite separation. Bioremoval of arsenic ions (both arsenite and arsenate ions) by Acidithiobacillus ferrooxidans is also discussed.

Jan 1, 2009

By Hideo Ando, Yuka Satou, Tatsuya Ishitake

Whole-body vibration occurs when the body is supported on a surface which is vibrating. Occupational exposures to whole-body vibration mainly occurs in the transportation industry, but also in association with other industrial process. Epidemiological studies have frequently indicated an elevated health risk for the spine in workers exposed to whole-body vibration. With regarding to train or bus operators, a fall of drivers’ wakefulness level because of fatigue is often pointed out. This decrease in wakefulness results in an increase of the occurrence of accidents. However, a study of how whole-body vibration affects people&apos;s level of wakefulness has not been done. To test the hypothesis that exposure to whole-body vibration has a certain effects on level of wakefulness, the change of a subjective wakefulness level and changes of electroencephalogram (EEG) were observed under experimental exposure to short-term whole-body vibration. Methods Subjects are ten healthy male university students, with an average age of 20.7 ± 1.8 years old, and they are all nonsmokers. Using the equipment (CV-300, AKASHI) of whole-body vibration generator, we consider an exposure environment of actual driver work, so that set the frequency and the acceleration level as 10 Hz and 0.6ms-2 r.m.s.. The subjects were exposed to whole-body vibration in the seated position and exposure time was fixed for 12 minutes. Subjective wakefulness level was evaluated using the questionnaire of VASS (Visual Analog Sleepiness Scale) and KSS (The Kwansei Gakuin Sleepiness Scale). For the electroencephalogram (EEG) measurement, it was equipped with the electrodes based on the International ten-twenty electrode system (C3-A2, O1-A2, O2-A1). EEG activity in the alpha frequency band (8 – 12 Hz) is one of the most typical physiological indicator which represent the transition from wakefulness to sleepiness. AAT (Alpha Attenuation Test) which repeats three times each opened and closed eye for 1 minute was performed in a seating position with directions of the researcher in the beginning, in the middle and in the end of exposure to whole-body vibration. For analysis, power spectral analysis was conducted over the last 6 min of EEG, and wakefulness levels were defined as the ratio of mean alpha power during eyes closed versus eyes opened. The laboratory was kept at room temperature (21 ± 1.0 degrees C), humidity was 50 ± 5%, noise level was 63.6 dB (A) eq, and illumination 510 lx. Each experiment was started around 10:00 am to minimize the effect of biorhythm.

Jan 6, 2006

By R. E. Simpson

Beginning in 1972, fully grouted resin bolts were used in underground mines. An estimated 20 million resin bolts will be installed in 1980 owing to their apparent support improvement in most roof-bolt applications. Inorganic cements were tested to replace the resin at a lower cost while retaining the advantages of a grouted bolt. Although other inorganic materials were considered, all but portland and gypsum cements were rejected for reasons of availability, performance, or cost. Portland and gypsum-type cements were tested by the Bureau of Mines to select a fast-hardening, low-cost material that would anchor a roof bolt adequately to meet safety standards. An alpha-gypsum cement, accelerated with potassium sulfate, was selected as the best material because it had adequate pull strength at a desired set time of less than 5 minutes and was readily available.

Jan 1, 1980

By H. M. Lawrence

"Florida, the State that supplied 82 per cent of the phosphate rock sold in the United. States in 19284, has two producing areas - the hard-rock and the land pebble districts. Production of the hard-rock field, decreasing importance in recent years, is now confined to mines near Dunnellon, in Marion and. Citrus Counties. The land-pebble district, with a production of almost 80 per coat of the nation's requirements, is located, in Polk and Hillsborough Counties. In the land-pebble area the phosphate deposits - probably Pliocene in age, derived by marine action from underlying, older, phosphate-bearing formations - consist of beds of phosphate matrix, covered by practically barren sands and clays. The overburden, ranging in thickness up to 45 feet, is removed by hydraulic methods or by drag-line excavators. The matrix, ordinarily less than 25 feet in thickness, is mined by hydraulicking and is pumped to adjacent washing plants for beneficiation. The dried product of the washing plants is the Florida pebble rock that is sold in foreign as well as domestic markets.The beneficiation of phosphate ores in the land-pebble district of Florida has been largely limited in the past to the recovery of the coarser pebbles. By washing and screening the crude matrix a separation is effected at about 20 mesh (0.033 inch). The coarser material is the phosphate-rock product of the plant and the finer material is discarded. The amenability of the washer- rejects to treatment by other processes is being investigated. Of methods that may have some application to the treatment of the low-grade phosphatic sands that comprise the greater portion of the washer-rejects, gravity concentration has received some study.Laboratory experiments to determine the amenability of phosphate sands to gravity methods of concentration were first performed in October, 1927. Later, in the winter of 1928-1929, a further series of teats was made,. In these later tests phosphatic sands were concentrated by hydraulic classification, and. also by hydraulic classification followed by tabling. In these experiments concentrates with an analysis above the minimum grade of commercial phosphate rock (66 per cent bone phosphate of lime - B.P.L.) obtained. The recovery of the phosphate varied but was promising enough to warrant further study. A more comprehensive investigation was therefore outlined. This paper presents the results obtained from an investigation, of classification and tabling of phosphatic sands recently completed by the United States Bureau of Mines Su cooperation with certain Florida phosphate companies, the Missouri School of Mines and Metallurgy, and the University of Alabama."

Jul 1, 1930

By Grant Buma

Groundwater restoration is an uranium leaching. Information on the technology, costs, and the current permitting regulations is of vital operators and to firms considering in important aspect of in situ effectiveness of the current state and federal government importance to in situ leach situ leaching. This study, funded by the U. S. Bureau of Mines, describes: (1) all recent restoration attempts at commercial in situ leach operations, (2) restoration costs reported by the industry, (3) empirical equations that predict the amount of groundwater flushing required to meet the current restoration criteria, and (4) in situ uranium permit requirements for the states of Texas, Wyoming, New Mexico, Utah, Montana, Colorado and South Dakota, and Federal requirements.

Jan 1, 1981

By G A. Wellwood

What do all iron ore mines have in common? Perfect production days! Yes, those harmonious 24-hour periods when the stars align and the daily output number rockets past the long-term average to hit new heights. While perfect days are always welcome, the focusing question iswas that just a ‘flash in the pan’ (due to a special cause) or an indication of the process’s capability (with clues to the common causes) which, if addressed, could make every day perfect? In the context of today’s operating environment, with the need to maximise productivity at minimum cost, it’s an important question.Investigations reveal that the throughput difference between a perfect production day and the average is often in the order of 40 per cent, and that bulk solids handling (BSH) system deficiencies are the largest (&gt;50 per cent) class of lost opportunity. Root causes for underperformance of elements in BSH systems can often be traced back to the detailed design and even study-stage oversights. Essentially baked into the fabricated plant, operations are effectively forced to accept them at the point of practical completion and then deal with the consequences for the life of the mine. Subsequent normalisation of these defects in the planning process reduces visibility and hence the impetus for long-term solutions in favour of lower targets and quick fixes to keep the show on the road. On an industry wide basis the design processes and assumptions responsible for BSH system underperformance become enshrined as common practice and hence repeated across sites and organisations.In addition to making the case for action, practical steps that can be taken to help realise the significant productivity prize and avoid the problems in first place are provided.CITATION:Wellwood, G A, 2017. One perfect (production) day – a bulk solids handling perspective, in Proceedings Iron Ore 2017, pp 443–452 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By J. P. D. Strydom

The transmission of excessive vibration to the human body can cause physical stress that may result in crippling pain or permanent disability. Rock drills are known to transmit high levels of vibration that are difficult to attenuate through conventional approaches to vibration isolation. However, it can be shown that once the ISO frequency weighting has been applied, most of the vibratory effect of the rock drill?s motion is concentrated at the drill?s operating frequency. This observation opens the way for utilizing a concept known as vibration absorption, aimed at attenuating the rock drill?s vibration. In essence this entails using the inertia of a secondary vibratory system to counteract the motion of the handle. This article documents an investigation into the use of such an absorber for attenuating rock drill vibration and demonstrates the feasibility of such an approach. A mathematical model of such an absorbing handle was developed and used for design studies. Based on these investigations an experimental prototype model was manufactured and tested. A significant reduction in vibration levels could be achieved.

Jan 1, 2002

By B. K. Parekh, Z. Chen

INTRODUCTION The need for cleaning and recovery of fine (minus 28 mesh or 0.5 mm) coal fraction has increased in recent years. This results from realizing a substantial recovery of ultraclean coal from the waste stream improving overall Btu (heat) recovery, providing extra revenue for the coal industry. Also the potential of using the clean coal so obtained for making coal-water mixture which could replace oil. An additional benefit of recovery clean coal from the waste stream is reducing environmental concern of burning uncleaned coal and in waste disposal. Deashing of coal by physical beneficiation processes is limited by the degree to which ash components are liberated from coal. Conventional processes have been inefficient in terms of Btu recovery, for ultrafine coal. Chemical cleaning methods, which involves leaching of ash material from coal, have provided ultraclean coal at high Btu recoveries, are more costly than the physical cleaning methods. An advanced physical separation technique that appears to address the need discussed above is selective flocculation. This technique which has been successfully utilized in iron ore beneficiation offers the potential of processing fine and ultrafine coal to produce a clean fuel. OBJECTIVES The main objective of the present study is to investigate applicability of selective flocculation technique for recovery of clean coal product from the waste coal slurry supplied by the Peabody Coal co., from their three different coal preparation plants. It is also the objective of the program to conduct preliminary economic study of the selective flocculation process.

Jan 1, 2002

By William N. Patterson

Drive systems for mining machines are usually sized to accommodate anticipated peak loads. Usually, the average power requirements are considerably less. Energy storage and power averaging are attractive concepts for mining machinery and could have far-reaching implications. The purpose of this program was to: ? Identify truly feasible concepts, ? Identify advantages/disadvantages, limitations, and constraints, ? Evaluate feasibility based on today?s technology, ? Identify anticipated safety problems, and ? Provide the designer with a comprehensive literature base. Concepts evaluated include flywheels, high energy batteries, gas charged accumulators, inductive storage, capacitive storage, springs and counterweights, thermal, closed cycles, internal combustion engines, trolley systems, and hybrid systems. A comprehensive reference index is provided. Included is an appendix containing abstracts of the pertinent literature.

Jan 1, 1980

By M E. Pierce, T V. Garza-Cruz

Rock mass strength and brittleness generally have a significant impact on both cavability and fragmentation. Variability in these properties across a panel or block footprint is of particular interest because stronger units have the potential to significantly impact cave shape. This paper describes how FLAC3D™ was used to examine the impact of variability in rock mass properties on predicted cave performance to aid in assessing potential risks associated with the proposed design.A case study orebody was subdivided into a number of domains to reflect the heterogeneity of the rock mass at the scale of a proposed inclined cave. The results suggest that the presence of stronger units has the potential to impact cave shape significantly in the southern half of the cave footprint and could increase the potential for cave stalling at shallow depths. If this unit is stronger and less brittle than expected, an overhang is predicted to develop in the southern half of the inclined cave at depth. The effective hydraulic radius is significantly reduced due to the overhang in the south, and the cave could eventually stall at shallower depths in the north.CITATION:Garza-Cruz, T V and Pierce, M E, 2016. Impact of rock mass strength variability on caving, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 359–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By J. J. Shields

This study by the Federal Bureau of Mines concerns different methods of face haulage used with various types of continuous-mining machines, mobile-loading machines, and track-mounted equipment under varying roof and bottom conditions and in coalbeds of varying thicknesses. This report is the ninth in a series on mechanical mining in bituminous coal mines. Reference to the reports previously published is made in appendix III, p. 106. Use of modern mining equipment in bituminous coal mines has resulted in increased productivity at the face. This especially is true where continuous-mining machines are used, and the supervision is good. Previous methods and equipment for moving coal from the face became inadequate and had to be improved to restore balance to the mining systems. Sometimes new equipment was needed to improve the face haulage, and in some instances, a new combination of existing equipment was used. Detailed studies of face haulage methods were made at 13 mines in Pennsylvania, West Virginia, Ohio, and Illinois to compare their effectiveness and to describe fully the conditions under which each method was used.

Jan 1, 1960

By W. Randall, Robert M. Leary

Twin 1250 m (4100 ft.) long highway tunnels through Cumberland Mountain near Middlesboro, Kentucky are planned to be completed in the early 1990&apos;s. The tunnels will be excavated in sandstones, limestones, and shales, dipping at 35 to 50 degrees and striking nearly perpendicular to the tunnel alignment. In 1985-86 a pilot tunnel was excavated as a crown drift along the alignment of the southbound tunnel. The benefits of the pilot tunnel in reducing uncertainties for main tunnel construction are discussed. The cost-benefits of the pilot tunnel are examined in view of estimated main tunnel costs.

Jan 1, 1987