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By Deno M. Pappas, Christopher Mark, Eric R. Bauer

During 1998-99, groundfall incidents resulted in 27 fatalities and were responsible for over 70% of all deaths in U.S. underground coal mines. To obtain a better understanding of where and why these incidents occurred, a comprehensive analysis of ground fall injuries and fatalities was conducted. The first portion of the study examined various factors associated with roof and rib fall injuries and reportable roof fall noninjuries that occurred during 1995-98. The study found that the room-and-pillar mining method has twice the groundfall incident rate than the longwall method. Mine locations with high groundfall rates seem to correlate to regions where there is a higher concentration of problematic coalbeds. For example, the Illinois Basin has very high groundfall rates, which can be traced back to several key coalbeds-Kentucky No. 13, Herrin/No. 6/Kentucky No. 11, and Springfield No. 5/Kentucky No. 9. High rib fall rates were found in mines located in thick seams. Groundfall rates were found to be 30% to 40% higher during the months of July through September, possibly due to high humidity that may cause the shale mine roof to deteriorate. The second part of the study examined the root causes of failure by reviewing all groundfall fatality reports for 1996-99. Primary and secondary hazard factors were assigned to each groundfall incident. The primaryf actors resulting in these groundfall fatalities were pillar extraction, traveling under unsupported roof, skin failure, construction, longwall faces, intersections, and geologic discontinuities. Defining prominent ground control incident trends and hazards will identify areas where additional study is needed and where innovative solutions need to be developed to reduce these severe occupational hazards.

Jan 10, 2000

By I. Iwasaki

The steel industry is facing an unprecedented challenge. I would like to point out the role that flotation technology could play in meeting this challenge by providing high quality raw materials to the steel industry. Of all the technology available to a blast furnace operator, raw material preparation is by far the most important. Raw material preparation has been a key to the success of the Japanese steel industry. The foremost proponent of better raw material preparation was Professor Joseph at Minnesota. He gave a Howe memorial lecture to the AIME audience in the early 1950s, prepared from the lecture notes that he gave in his classes. At about that time he was invited to Japan. It is ironic that the Japanese steel industry listened and made it a success. In order for our steel industry to be competitive, first we must supply high quality and uniform quality raw materials to improve the efficiencies of our blast furnaces. Where does flotation fit in to the iron ore industry then? First, as a primary means for concentrating for oxidized iron ores. Second, to touch up magnetite concentrates for the removal of the last few percent of silica. And third, in the preparation of super-concentrates for direct reduction.

Jan 1, 1984

By Sidney A. Swensrud

This paper reviews the subject of gasoline margins, discusses some of the more current marketing problems, and gives some consideration to the main urges to marketing expansion, or overexpansion, in the oil industry. Margins In an earlier paper1, some comparisons were shown for the years 1929, 1930 and 1931, of the margin between the refinery cost of gasoline in Oklahoma, the market price in Oklahoma, and the average retail price in 50 representative cities of the United States. These figures indicated a small margin for the refiner in 1929 between his gasoline cost and the wholesale price, which, however, had turned into a loss by 1931. The margin between either refinery costs or wholesale prices and the retail price in the 50 cities showed a continuous decline during the three years. We have now worked out these figures on a similar basis for a longer period—from 1928 through 1936. The figures for refinery gasoline cost are slightly different from those in the earlier study, owing to the use of

Jan 1, 1937

By B. A. Chomyn, P. Lapointe

Current work within the Magnetic Properties Task of the Canadian Nuclear Fuel Waste Management Program has indicated that a relation exists between the measured bulk magnetic susceptibility and fracture and lithological characteristics of granitic cores from the Lac du Bonnet batholith in Manitoba. Susceptibility minima correspond to fractured and associated altered rock; uniform background levels coincide with unaltered, non-fractured homogeneous rock; and susceptibility maxima denote the presence of xenoliths and intervals of core containing large and coarse-grained magnetic minerals. The observed variation in bulk susceptibility is largely controlled by the gram size and the relative abundance of iron-titanium oxide minerals of which magnetite is the most important. The magnetic minerals occur as monomineralic grains of magnetite and hematite, as aggregates of magnetite and ilmenite, hematite and ilmenite and as examples of either of these two categories but exhibiting evidence of oxidation and alteration. The degree of alteration of the oxides is commensurate with the alteration of the enclosing rocks. Susceptibility minima characteristic of fractured rock reflect decreases in oxide gram size and abundance, as a result of the oxidation of magnetite to hematite and the development of titanium-rich phases. Correlations between boreholes indicate the possibility of continuous fracture zones at 80 m and 150 m from the surface and another one at a greater depth.

Jan 1, 1984

By E. J. Roberts, E. B. Fitch

THE mechanism of classification by settling pools is most simply shown in the case of batch sedimentation such as was analyzed by Oden.1 The batch model will be considered, therefore, and it will be shown that the same mechanism applies to continuous operation. Classification in Batch Settling Pools: Consider a beaker or tank of slurry containing particles so dispersed that they can settle independently of one another under the influence of gravity. Originally all particle sizes are uniformly distributed throughout the suspension. All particles start immediately to settle towards the bottom at rates determined by their size, shape, and density—among other factors. Particles reaching the bottom settle out of suspension. After some given time the slurry above the deposited solids is siphoned off or otherwise removed, leaving the deposited solids behind. The deposited solids, together with entrained and any unremoved supernatant slurry, represent the underflow of a classifier. The slurry removed represents the overflow. There is a certain separation, size of particle which during the sedimentation has just time to settle from the top surface of the slurry to the level at which underflow and overflow are parted. All particles with a faster settling rate will have dropped to below this level, no matter where in the beaker they started from originally, and therefore will be absent from the overflow. Particles with a slower settling rate will not reach this level if they started from the top of the slurry, but a portion of them,

Jan 1, 1957

By J. Richard Kyle

Lead-zinc ore bodies in the upper part of the Pine Point carbonate barrier complex are localized in paled-solution structures that developed as the result of post-middle Givetian subaerial exposure. Detritus-filled dolines host prismatic ore bodies, and macropores and stratabound permeable zones contain tabular ore bodies. Sulfides are concentrated in these transgressive paleosolution structures that acted as natural bypasses between aquifers and loci for mixing of fluids of different character. Complex ore textures indicate rapid early sulfide precipitation followed by slower sulfide growth. Evidence for both sulfide-carbonate equilibrium and disequilibrium conditions suggest fluctuations in ore fluid composition, perhaps related to periodic supply of reduced sulfur. District and ore body metal distribution pattern may reflect the nature and movement of mineralizing fluids.

Jan 1, 1981

By Eung Ha Cho, Olufemi Olajide

A laboratory study of dense-medium cycloning with Redstone seam coal has been conducted. The investigation was performed using a 203 mm (8 inch) Heyl-Patterson dense-medium cyclone. Two underflow orifices of 31.8 mm (1.25 inch) and 44.5 mm (1.75 inch) in diam were used. The effects of feed pressure and particle size were determined on the cycloning performance. In addition, the cyclone performances with coal-rich and refuse-rich samples were also investigated. The results of the experiments were analyzed using basic hydrodynamic principles. The increase in the feed pressure increases the specific gravity of separation (defined as the specific gravity of a particle which has an equal chance of reporting to either the overflow or underfow) for both underfow orifices. The specific gravity of separation increases as the particle size decreases with the smaller underflow orifice. However, an opposite relationship has been observed with the larger under flow orifice. The separation becomes sharper with the smaller under flow orifice than with the larger underflow orifice especially for fine material. Also, the separation becomes sharper with an increased feed pressure for a coal-rich sample. However, this effect is less significant for a refuse-rich sample. This means that a high feed pressure is required for a coal-rich sample to maintain a good separation. It also means that applying a high feed pressure provides a good separation regardless of the type of feed coal in terms of ash content in the solid.

Jan 1, 1990

By Williams J. D

Magnetite has been used in coal processing for many years and it is likely that its use will continue well into the twenty first Century. While magnetite is only a minor cost component in coal processing, the use of processed magnetite in dense medium separation is essential to provide the split of quality coal products which the markets of today demand. The occurrence of magnetite in Australia is relatively abundant, but a combination of its iron content, magnetic properties, quality and proximity to the coal processing plants is essential to provide a low cost product for use in the Coal Industry. The demand for more splitting of coal in coal processing may require more grades of magnetite, particularly as a finer grade lower specific gravity medium to separate the finer quality low ash coals.

Jan 1, 1991

By New kensington P. A, W. L. Fink, H. R. Freche

The investigation of aluminum alloy systems prior to 1923 was severely handicapped by the low purity of the best aluminum available. However, by that time, the electrolytic purification of aluminum had been developed by the Aluminum Company of America,(1)† and in May, 1923, there was initiated, under the direction of E. H. Dix, Jr.,(2) a program for the investigation of the aluminum-alloy systems using the purest electrolytically refined aluminum. Up to the present time 15 papers (3) have been published, most of which are on the binary aluminum systems. Work is now in progress on the ternary systems, and it seems probable that most of the future work will be on ternary systems. Therefore this survey of the binary aluminum systems investigatcd up to the present time (the sixteenth paper of the series) concludes the first phase of this program. Certain qualitative relations between corresponding portions of the various binary diagrams as well as between different parts of the same diagram were noted some time ago by R. S. Archer.(4) In the present paper these relations and others are considered quantitatively by the application of well-known thermodynamic equations or by newly discovered empirical relations. No attempt will be made here to present the history of the development of the thermodynamic equations defining equilibrium or their application to metallic systems, although a list of references is given at the end of this paper for those who are interested in this phase of the subject. Two thermodynamic equations, which will be employed extensively in this paper, are: loge x1 = - L/RT + C

Jan 1, 1934

By George Mansfield

INTEREST in the reserves of phosphate rock in the United States and their proper conservation has recently been aroused by hearings held in different parts of the country by the "Joint Committee to investigate the adequacy and use of phosphate resources of the United States." This committee was appointed within a few days after a Presidential message to Congress on the same subject, dated May 20, 1938, and began to function almost immediately. Hearings were held in Washington, D. C., Pocatello, Ida., Wilson Dam, Ala., Knoxville, Tenn., and Lake-land, Fla. The resulting testimony, when published, comprised a volume of 1182 pages.1 At the earlier hearings held in Washington and Idaho the seeming disparity between the great reserves of the West and the smaller reserves in the East led to some suggestions as to the desirability of curtailing or even prohibiting the exportation of phosphate rock so that eastern pro-ducers, becoming alarmed, cooperated in making available for the use of the committee information hitherto closely guarded. This informa-tion has provided an opportunity for new studies by official agencies, for a restatement of the reserves of Florida and Tennessee, and for some modification of figures for the Western States. The writer, representing the Federal Geological Survey, was given free access to the Florida material and has prepared for publication a report,2 some features of which are summarized in this paper. The Tennessee material was studied by Dr. G. I. Whitlatch,3 of the Tennessee Division of Geology. Prof. J. Stewart Williams,4 of the Utah State Agricultural College at Logan, has published a recent study of the phosphate resources of Utah and the writer has given some further study to reserves of western phosphate from the viewpoint of including material of lower grade than that hitherto considered.

Jan 1, 1940

By Marc Lemieux

A new moving cone optimizing technique will be introduced. In order to facilitate under- standing of the moving cone optimizer, a re- view of the principles of moving cone design technique is presented. A concept called the negative moving cone design technique is also introduced to help facilitate understanding of the moving cone optimizing algorithm. In the introduction to Subsection 3.3, the relationship of the mineral inventory modeling technique to the ultimate pit design optimization methods was reviewed. Five modeling techniques were described, and four mathematically provable optimizing methods discussed. The broad use of the regular 3D fixed block model was attributed, in part, to its applicability to automatic optimization methods of pit limit design such as the Lerchs-Grossman graph theory algorithm, and in part, to its systematic nature.

Jan 1, 1979

By Charles Vaught, Belinda Sue Mills, Henry P. Cole, William J. Wiehagen

This study reports the results of a survey of organizations that used problem-solving simulation exercises to support mine health and safety training. The exercises are designed to teach judgment and decision-making skills within two broad domains: (1) how miners respond to mine emergencies (e.g., first aid, self-rescue, and escape) and (2) how miners integrate safety concepts within the context and performance of routine production work. The simulation exercises were distributed by the Mine Safety and Health Administration's National Mine Health and Safety Academy near Beckley, WV. The present study focused on those organizations that ordered the exercises from the Academy over a 2-year period (1995-96). Researchers assessed how the materials were used and trainer perceptions of the impact of these materials on annual mine health and safety training . A total of 147 organizations ordered the exercises over the 2-year period. Survey responses were obtained from 52 of these organizations. Sixty percent of the respondents rated the exercises as more useful than traditional instructional materials, 40% as equally useful, and 0% as less useful. Most trainers (79%) felt that the exercises help them to make better use of workers’ knowledge and experience during training. Many (71%)also reported that the simulations helped to improve the effectiveness of their instruction and promoted a problem-solving approach to their training. Fifty of the fifty-two respondents reported that they would like to have new simulations developed. A large majority showed a proactive interest in helping to develop and field test new exercises. Ninety-four percent of the trainers judged the exercises as a good value; 92% planned to order more simulations in the future. Based on this study, recommendations are offered for the continuation and expansion of simulation exercises as one method for occupational health and safety training.

Jan 1, 2001

By A. F. Colombo

In an effort to maintain an adequate supply of iron to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, is conducting research on methods for beneficiating the oxidized taconite resources located on the western Mesabi range in Minnesota, thus expanding domestic iron ore reserves. The selective flocculation and cationic flotation process was investigated in a pilot plant using an ore feed rate of 410 kg/hr (900 1b/hr) and 88 percent recycled water. Lime and a cationic flocculant were used to clarify the waste slurries treated in the water reclamation circuit. An oxidized taconite assaying approximately 36 percent Fe yielded concentrates averaging 63.5 percent Fe and 4.3 percent SiO2 and having an average iron recovery of 84.4 percent. The estimated reagent cost per tonne of concentrate was approximately $1.10. In an attempt to recover more of the iron lost in the flotation tailing, wet high-intensity magnetic (WHIM) separation was incorporated in the pilot plant circuit. The flotation concentrate grades obtained from beneficiation circuits with and without WHIM scavenging were similar, but when WHIM separation was used the overall iron recovery was increased by 2 to 9.5 percent, depending on the iron assay of the flotation tailing.

Jan 1, 1978

"Chairman - To start this discussion off, I wonder if Mr. Dave Livingstone or Mr. Jeffrey of Granisle Copper would give a description of the crushing plant at Granisle since it is somewhat different from the usual plant, W. N. Jeffrey - Granisle Copper The main difference between the Granisle crushing plant and many others is the Livingstone method of putting the screens under the crushers instead of above them. This method allows a more compact arrangement and eliminates the heavy superstructure required to take care of the screen vibration when the screens are mounted above the crushers. There is a small surge bin above the tertiary crusher which takes care of the variation in circulating loads.All three crushers are gyratory crushers. There is no grizzly ahead of the primary crusher but the fines are removed from the primary crusher discharge at the first screen and sent directly to the fine ore bins. E, Thornton - Sullivan GroupDo you have any coarse ore storage outside?w. N. Jeffrey - Yes, there is about 6000 tons live storage, We have very little trouble with freezing even though it is open storage.E. Thornton - Sullivan GroupDoes rain cause any problem?w. N. Jeffrey - It sometime creates a problem because the storage area is on a slope. It is mainly a problem of keeping the drainage ditches open.Question – What is the size of the primary gyratory crusher and how does it work on run of mine size materials, in other words, do you have a problem with oversize material and how do you handle the oversize rock?w. N. Jeffrey - The primary gyratory is a 42 x 65 with a nominal open side setting of 61'. We do at times get a run of oversize material. For anything too large for the crusher to handle, we use what is known as the Esco hook, which is a type of grapple used to remove oversize rocks.The disadvantage with this equipment is that the crane is too slow. I am sure there must be better arrangements than the one we have,"

Jan 1, 1971

By Norman D. Fitz Gerald

THE growth of domestic requirements for motor fuel has been phe-nomenal, rising year after year in a fashion almost unique among com-modities, resisting depressions and forging rapidly ahead in times of prosperity. Consumption advanced from 226 millions of barrels in 1925 to 522 millions of barrels in 1938; or 130 per cent. The economic influ-ences generating and sustaining this demand are of vital concern to the petroleum industry. The general factors affecting utilization of motor fuel are well known but it is the purpose of this paper to employ the recently developed technique of economic dynamics to describe them mathematically. Such problems in economic analysis are complicated by the freedom of all the variables to fluctuate, their mutual interdependence, changing incidence upon one another, and the nonquantitative character of some of them. Economic quantities and relationships, unlike those of the physical world, are continuously changing and this dynamic characteristic is both a distinguishing and confusing feature in economic research. The com-plexities of the problems require application of the analytical devices of mathematical statistics to uncover the probable relationships between factors. The procedure employed is to formulate a logical relationship linking the dependent to the independent variables, and then simul-taneously, rather than sequentially, determine their separate effects by multiple correlation. This transformation of common knowledge to quantitative terms makes it possible to measure the probable effects of changing conditions upon requirements, assisting in the sound interpreta-tion of economic policies. The utility of the results of such dynamic analysis is in sharp contrast to the sterility of the trends and other simple empiricisms of descriptive statistics. It is not intended in this study to throw light on the reasons why any motor fuel at all is consumed; but to discover relationships explaining why more was consumed at one time than at another. Specifically the prob-lem is confined to the measurement of the influences of statistically

Jan 1, 1940

By Nick Barton

Simple methods for estimating the shear strength of rock joints and waste rock are reviewed. For the case of rock joints, the methods are based on a quantitative characterization of the joint roughness and the joint wall strength. Size-effects are found to reduce the peak strength of large joint samples to values below the ultimate or so-called "residual" values measured in the laboratory. Tilt tests and surface profiling on natural size blocks within the jointed rock mass are recommended for obtaining scale-free properties. The joint parameters obtained can be used to model complete strength-displacement-dilation behavior if this level of input is required. Large scale tilt tests can be performed with advantage on both rock joints and waste rock. The behavior of these two materials is surprisingly similar. Both are influenced by the size-effects on the compression strength of the rock, and both have similar log-linear relationships between effective normal stress and the peak drained friction angles. The resulting high values of friction near the toe or close to a slope face in either material can be misleading.

Jan 1, 1983

By Wu Y, Qu Q

The Central Coal Mining Research Institute has developed the MAE acoustic emission monitoring system, the BD4-1 portable acoustic emission monitor and the MRB rock burst monitoring system. In the MAE system there is an IBM-PLAT, a receiver and 16 channels and the investigating range is 100 m. The main functions are detecting acoustic events from the working faces, periodically making statistics, prints, displays and storing of the results, and performing the off-line process such as drawing the curves of acoustic activity. The BD4-1 instrument has four channels, it works for more than 24 hours continuously, and keeps the data for more than 30 days after power tum-off. The BD4-1 is suited to the monitoring for a long or a short time as a fixed point where the system is invalid, especially to the monitoring of the acoustic activity promoted by the blasting. There is an IBM-PC/AT, a receiver and 16 channels spread 10 km in the system MRB. The system could on-line collect microseismic events throughout the whole mine, calculate the source location and the energy, and off-line draw the seismic activity draft of time-based or distribution in space. In practice, the forecasting is successful by using the acoustic emission and microseismic monitoring system and the portable instrument.

Jan 1, 1991

By F. W. Gibson

A detailed description of the smelting and refining operations of the Amax-Homestake Lead Toller's smelter at Buick, Missouri. This is one of two completely new lead smelting and refining operations to go into operation in the United States in over forty years. Incorporated into the operation are the new methods and equipment which have been developed and lend themselves to the particular metallurgy of this plant. The text, as well as the statistical data presented, represent actual current practice after 22 months of operation, and although the metallurgy is considered to be relatively simple, several metallurgical problems unique to Missouri concentrates are discussed.

Jan 1, 1970

By Merry N, Cocks T

The mineral exploration industry is increasingly aware of the importance of the relationship between mineralogical data and geochemical assay results. However, until recently, the cost and time constraints of most techniques for analysing alteration mineralogy have precluded detailed alteration studies. These impediments have been reduced by the development of the Portable Infrared Mineral Analyser (PIMA), a field portable infrared spectrometer that allows rapid (in field) and cost effective analysis of alteration minerals including subtle variations in mineral crystallinity and Composition.

Jan 1, 1995

By A. L. Hinde, H. Dong, J. T. Kalala

"The High Pressure Grinding Roll (HPGR) is gaining acceptance in the mineral processing industry and has become a competitive technology in reducing the specific energy consumption in Mineral processing plants. The amount of samples required for HPGR amenability testwork and HPGR wear tests is usually high and often cannot be available at early stage of projects were only a few drill cores are available.Although HPGR was initiated from small scale piston die compression tests, the development of small scale piston die test to predict the performance of HPGR has been slow.The objectives of this paper was to present the designs, operating procedure of piston-die press and operating conditions which have resulted in similar particle size distribution obtained from a piston die test and HPGR Labwal unit starting from the same feed size distribution. Testwork were conducted using a 2 MN piston-die press and a Labwal HPGR unit on major South African ore types, viz, gold, platinum and iron ores. The results obtained show that piston-die test can generate data to predict energy consumption, product size distribution, and even to evaluate the edge effect."

Jan 1, 2012