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By Alex C. Smith

This report describes laboratory studies conducted by the Bureau of Mines on the spontaneous combustion of U.S. coals. Approximately 11 pet of U.S. underground coal mine fires are attributed to spontaneous combustion. The relative self-heating tendencies of 24 coal samples were evaluated in an adiabatic heating oven. Minimum self-heating temperatures (SHT's) in the oven ranged from 350 C for a lignite and high-volatile C bituminous (hvCb) coal, to 1350 C for two low-volatile bituminous (lvb) coals. An empirical expression was determined predicting a bituminous coal's minimum SHT in the adiabatic oven based on the coal's dry ash-free oxygen content. Several factors that can affect the self-heating process were also evaluated. The self-~eating tendency of a coal increased when the coal was dried and exposed to humidified air, and was dependent on the particle size and oxygen concentration of the air. A new moderate-scale apparatus is described, in which the self-heating tendencies of larger coal samples, 3 kg, can be evaluated. The minimum SHT's of two coals were determined and the results were in good agreement with those found in the adiabatic oven. Finally, results of a test in the moderate-scale apparatus indicated a strong dependence of the self-heating rate of a low rank coal on the moisture content of the air.

Jan 1, 1987

By S. A. Swensrud

NINETEEN Thirty-Six was the biggest year in volume in the history of the oil industry, and unquestionably the best since 1929 in respect to profits. The quota of new and difficult problems to face seemed a little smaller during 1936 than in most recent years, and a somewhat better balance existed between the different branches of the industry. 'Domestic consumption of gasoline in 1936, estimated at about 475 million barrels-the highest on record, was approximately 11 per cent above 1935, and 26 per cent above 1929. Demand for crude oil increased in about the same proportion: over 1935, and the average production, of about three million barrels daily,' constituted a new high level.

Jan 1, 1937

By Aiyuan Ma, Tu Hu, Chenyu Sun, Yonggang Zuo, Hongying Xia, Jinhui Peng, Libo Zhang, Yongguang Luo

"In this study, the adsorption characteristics of tannin acid in aqueous solution were investigated using regenerated activated carbon (AC), with the aim to remove the tannin acid organic matter from the solution after zinc hydrometallurgy and Ge precipitation. Results showed the temperature has little effect on the adsorption ability (q.) of the regenerated activated carbon. The experimental equilibrium data were tested for the Langmuir and Freundlich isotherms. The adsorption equilibrium was better described by the Langmuir isotherm (R2 > 0.99). Pseudo first- and second-order kinetic models were used for describing kinetic data. It was determined that the kinetics of tannin acid removal was well fitted by second-order reaction.IntroductionGermanium recovery is a complex processes [1]. Hydrometallurgical processes are favoured and these are based on the precipitation of germanium as hydroxide or sulphide or alternately with tannic acid [2]. However, in the germanium recovery process, too much tannin is consumed by the germanium-tannins complexation process, and results in a high content of tannic acid remaining in solution, which is harmful to the valuable metal recovery [3]."

Jan 1, 2014

By S. Frederick Ravitz

JUDGING from the inquiries that are constantly being received by the Utah Engineering Experiment Station as to the "Why," so to speak, of the flotation process of concentrating minerals, it occurred to me that perhaps a brief statement of the more important theories might interest those who have not followed the technical literature. Like many other industrial processes, flotation has hitherto been developed on an almost purely empirical basis, with relatively little practical contribution from the fundamental chemistry and physics on which the phenomena are based. In fact, its development by the trial - and - error method has been perfected to such a high state that it is becoming generally thought that further important advances can be brought about only by a thorough understanding of the actual mechanism of the process. Natur¬ally, such a complicated process has brought forth numerous theories, most of which have failed to withstand the test of time. It is significant that no theory has yet been advanced which is universally accepted.

Jan 1, 1933

By S. M. Dar

The U.S. Bureau of Mines constructed a full-scale model of a 15-ft-wide coal mine entry to use in combination with finite-element analyses to investigate roof support systems and various types of roof bolts. The objective was to enhance understanding of the fundamental mechanics of the interaction between rock and supports and the relative integrity of bolted mine roof as a function of roof bolt type, length, spacing, and tension, and the basic characteristics of the roof strata. The laboratory test results, when correlated with computer simulations using fmite-element analysis and underground verification tests, should provide a basis for desigillng safer, more cost-effective roof control systems and help to establish guidelines for employing fully grouted resin and mechanically anchored bolting systems. The background for this research, the research approach, the methods and equipment employed, and the results are described in this report.

Jan 1, 1989

By E. J. Lintner

This paper is one of a series being prepared by the United States Bureau of Mines describing cloy reining, crushing, and grinding methods and costs at various operations throughout the United States. These Toners are designed to disseminate technical information regarding methods used. The cost tabulations represent local operating expenditures only and not total production casts. Although the publication of total production cants might not be advisable in sore instances, yet a knowledge of operating costs is essential to the technical discussion end study of the methods employed. The attention of the reader is specifically coiled to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. The following report deals specifically with the methods employed by the Clay City Fire Co., Uhrichsville, Tuscarawas County, Ohio.

Jan 1, 1936

By A. D. Huffman

This paper covers the major salt deposits of Canada, with a brief summary of the early history of the industry and a more extended outline of progress since the second world war. Both dry mining and solution mining are covered, and the future of salt mining in Canada is discussed.

Jan 1, 1968

By K. Galos

The paper presents increasing importance of mineral secondary and waste raw materials in the minerals management in Poland. Definition of mineral secondary and waste raw materials is proposed, according to current Polish law. On this basis, sources of various types of mineral waste raw materials are analysed. The special attention is paid to the wastes from mining and processing, wastes from power plants, and wastes from steelworks and other smelters. Other types of waste and secondary materials, such as metallic containers, glass containers, batteries, metallic wastes and scraps, are also taken into account. Analysis of sources of such materials is shown together with the main directions of their economic use. Available sources of information on manufacture and use of the mentioned secondary and waste raw materials are also analysed. Finally, for a wide range of waste materials, their current and expected significance as substitutes for some industrial and construction minerals in Poland is given.

Jan 1, 2011

By Chas Kemsley

NO. 6 shaft at Dome Mines, Limited, is an internal shaft going down vertically from the sixteenth, or 2,000-ft., level to the twenty-ninth, or 4,000-ft., level, with loading station and sump below this. It is located approximately 4,600 feet east of No. 3 shaft, the latter being Dome's main shaft through which ail ore, men, and material are handled. The decision to sink this shaft was made in May, 1935, and work was commenced almost immediately. To reach the site of the new shaft, 3,100 feet of cross-cutting, and 1,400 feet of slashing to widen existing cross-cuts, was necessary. On account of the long haul and the large amount of material to be handled, trolley haulage was decided upon and installed as soon as possible to facilitate the removal of waste rock from the crosscut and other necessary excavations. Figure 1 shows a cross-section of the cross cut and the manner in which the trolley wire is supported and guarded. For hanging each individual cross-piece, two holes are drilled into the roof and filled with snug-fitting wooden plugs. Into these, %-in. ragged hanger bolts arc driven by means of a stoper. The bolts are of various lengths to allow for irregularities in the face of the rock, and they have sufficient thread to permit several inches of adjustment for proper alignment of the cross-pieces. These hangers are spaced at 8-ft. intervals except at the curves, where 5-ft. spacing is used. A 2 in. by 6 in. cedar plank is fastened to the cross-pieces directly over the centre of the track. To this the trolley-wire supports are bolted, and 1 in. by 10 in. cedar boards are nailed on each side to act as guards. Two power-supply cables, one telephone cable, and one .Y2-in. conduit lighting circuit are also supported on the trolley-wire hangers, as shown in Figure 1. A 20-in. ventilating pipe and a 10-in. air line are placed as shown, thus acting as a guard to prevent workmen from walking on the track.

Jan 1, 1938

By William O. Vanderburg

This paper describing the mining practices at the Argonaut mine, Amador County, California, is one of a series being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The mining practices described are those used in exploiting the low-grade gold ores in the heavy and swelling ground that occurs on the Mother Lode belt. The author acknowledges the assistance of E. A. Stent, vice-president, James L. Fontenrose, cost clerk, Joseph Mohorovich, mine foreman, of the Argonaut mine, and of E. D. Gardner, supervising engineer, United States Bureau of Mines, Southwest Experiment Station, Tucson, Ariz.

Jan 1, 1930

By M. Bunch

"THE SUPER CYCLE IS GONE The utopia of the rising sales volume, for mining companies from 2002-2011, was entirely due to rising production volume and prices. The Australian mining sector experienced an 18 percent annual growth rate in revenues, and 11 percent growth in prices. (1) However, EBIT remained flat during the same time period. In addition, Australian mines saw a 7 percent annual decline in both labor and capital productivity. (2) Mines in the U.S. and Canada produced similar results, whereas the world-wide mining industry has seen a productivity drop of 40% since 2001. (3) The decade “Bull Run” of rising prices was trashed by companies that chased low-quality assets while increasing debt on their balance sheet. It seemed everyone believed the “super cycle” would last forever, while completely ignoring the history of cycle downturns. Worldwide mining operations are as much as 28 percent less productive today than a decade ago, according to new McKinsey research. The results from McKinsey’s new MineLens Productivity Index (MPI), which adjusts for declining ore grades and mine cost inflation, show that the pronounced decline in productivity is evident across different commodities and is seen in most mining players and geographies. (4) McKinsey sees three important areas of focus to address the root causes of productivity decline. 1) Embed effective management operating systems at mines 2) Prioritized operational excellence and capabilities development 3) Focus on innovation Reality has now settled back in and companies are struggling to make ends meet. The basic management staple of controlling costs and improving the production/productivity that was lost in the excitement is now back in play. Traditional cost-cutting approaches, such as across-the-board spending cuts, layoffs, and hiring freezes are only short-term initiatives and will not permanently improve a company’s cost structure or improve long- term competitiveness. This can only be accomplished by engaging front-line employees and empowering them to make necessary improvements in their daily work. It is time for leaders to lead and develop cultures of continuous improvement within their organizations in order to sustain their mining project to the end of mine life. Successful operating managers require two different skill sets of Leadership and Management; knowing how to lead people in their organization and how to manage the work they do."

Jan 1, 2016

Since March 28, domestic producer prices on 99.5 percent aluminum ingot have been at 5l¢ per pound. Dealers in this same time frame have held ingot quotes at 49¢-50.5¢ per pound. COBALT: Imports from southern Africa in 1976 constituted 73 percent of total cobalt imports. Moreover, the United States is 98 percent dependent on imports of cobalt. For this reason, the Bureau of Mines is closely monitoring developments abroad to ensure an advance notice of any possibility of a shortfall in supply. Included in these imports were those from Zaire (41 percent directly from Zaire and 15 percent via Belgium-Luxembourg), Zambia (11 percent), and Botswana (6 percent). Also being closely watched are industry stocks.

Jan 1, 1977

By Gary E. Sherman

To aid the U.S. Army Corps of Engineers In their Resource Development Navigation Study, the U.S. Bureau of Mines (Bureau) examined the potential for mineral development near ten Alaska port sites. This report presents the results for the first three sites: Bethel, Kivalina (Red Dog), and Omalik Lagoon. The mineral deposits near Bethel are primarily gold and mercury; the nearest deposit being 55 mites away. Because of the expense of constructing and maintaining a road over the poorly drained lowlands, the potential of Bethel as a port site in the near-term is considered to be low. The Kivalina site currently serves the Red Dog mine and has the potential to handle material for similar deposits in the area. Results from a lead-zinc mine model indicate that potential for additional mine development exists in the area. Coal is the major deposit type found near the Omalik Lagoon site. Due to environmental constraints, development of a large-scale mine producing coal for export is considered unlikely. A small-scale coal mine model was used to examine the feasibility of producing coal for regional use. This alternative may be feasible but would require conversion of heating/generating equipment in the area.

Jan 1, 2011

By R. H. Kuhlman

The purpose of this paper is to describe the roles of cement and concrete in construction in general and, more specifically, as construction materials of the Southeast. For purpose of this discussion, the Southeast will include the geographic area composed. of the following 13 states: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, Virginia and West Virginia. In one sense, cement by itself is not a construction material. It is a finely ground manufactured mineral product, usually gray in color. Cement is mixed with water and sand, gravel, crushed stone, or other aggregate to form concrete, the rock-like substance that is the most widely used construction material in the world. Because cement is seldom used by itself for construction but is usually a component of concrete, there is no such thing. as a "cement" sidewalk, a "cement" highway, or "cement" building. Neither is "portland" a brand name. It is a generic term used to describe any cement that hardens in the presence of water and is made to standard specifications .. For all practical construction purposes, therefore, all cement is "portland." The name "port-land" was selected by the English inventor of the product in 1824 because concrete made with his product resembled natural building stone quarried on Portland, an English island. Although portland cement is not the final material which finds its way into completed construction, as the principal component of the most widely used construction material in the world, the location and process of its manufacture warrant some discussion

Jan 1, 1977

By J. B. Hadaway

The operation at Phu Kham commenced design and construction in early 2006 and was commissioned in May 2008. This paper will examine and discuss the project from the inception of flow sheet development and equipment selection, equipment design and manufacture, construction, commissioning and ramp up to full production. The paper will touch on the strategies employed to achieve a short schedule and the efficient use of capital, but with the main emphasis on the grinding circuit. Various challenges during the early years of operation will be discussed including the effect of ore characteristics, including competency, on the performance of the grinding circuit. Actions to overcome these challenges and to enhance performance will also be discussed. Finally, current and future plans to improve the performance of the grinding circuit and the overall plant will be summarised.

Jan 1, 2012

By T. Panhorst

Evaluation of through-deck blasthole sample reliability at the Lone Tree gold mine revealed a non-systematic bias in the sampling system. Ore is primarily hosted within the Powerline fault zone. Clay gouge, present in the fault zone and typically enriched in gold content, forms agglomerates during blasthole drilling leading to a segregation error during sampling. Replicated samples split from blasthole cuttings piles show through-deck samples to be either significantly enriched or depleted by 1.5 standard deviations or more from the mean gold content of their respective cuttings pile quality of through-deck samples correlates strongly with quantity of clay present.

Jan 1, 1999

By H. M. Park

Risk is a major factor in all mining activities, arising from many internal and external variables. The authors? research has resulted in a systematic method for the quantification of risk in mining projects (Park, 2012). This is the second part of a three-part series. The first part was published in the October 2013 issue of Minining Engineering magazine and can be found here at www.me.smenet.org. This paper discusses methods of assessing the overall risk associated with those variables, and presents a statistical model based on a survey of 31 experts. The third paper, to be publised at www.me.smenet.org on Oct. 14, presents an evaluation of the statistical model, using data from previous mining investment decisions in which the authors have been involved.

Oct 1, 2013

This paper describes the results of a laboratory study on the upgrading of Algoma siderite by the amine flotation of silica and silicate gangue. The experiments indicate that a virtually complete removal of silica is possible in a rougher flotation con-ducted in tap water at natural pH, without prior desliming of the ore. Grinding considerably finer than the apparent liberation size is essential for maximum silica rejection. A cationic collector, Aeromine 3037, gave best results when used in combination with a modifier. Of the several modifiers tested, a Dutch potato dextrin, Dextrin 4356, was found to be the most effective. Both iron recovery and the grade of the final iron product are enhanced by floating the pyrite contained in the ore prior to the amine flotation of the silica, and by scalping the magnetics from the silica concentrate. F OR over twenty years, the Algoma Ore Properties Division of The Algoma Steel

Jan 1, 1963

By John Fritz

TROUGH it is not a condition of the Award, the fact is that the John Fritz Medal never has been given to an engineer who had not already received one or more similar awards. This "medal for medalists," on the evening of April 20, was presented to Daniel C. Jackling at a special dinner held at the Union League Club in New York. The citation read "For notable industrial achievement in initiating mass production of copper from low-grade ores through the application of engineering principles." The present award recognizes the same accomplishment-the launching and guiding to the port of marvelous success of the Utah Copper Co., first of the so-called "Porphyries"-as did the award of the William Lawrence Saunders Gold Medal by the A.I.M.E. in 1930, and before that the Award of the Gold Medal of the Mining and Metallurgical Society of America in 1926. Following the custom a biography of the Medalist had been published in a small pamphlet as a supplement to the John Fritz Medal Book. T. A. Rickard was the au¬thor of the sketch of Mr. Jackling, an innovation being the placing of a copy of the booklet at the place of each of the diners. The committee in charge of the dinner consisted of two past-presidents: R. E. Tally, of the A.I.M.E., who was chairman; Bancroft Gherardi, of the A.I.E.E.; and Thaddeus Merriman, director of the A. S. C. E., the John Fritz Medal being a joint award of the four societies. Frederick M. Becket, President of the A.I.M.E., as chairman for the occasion, briefly stated the purpose of the dinner. He stressed his satisfaction that the award was symbolic of the cooperative professional activities of the four great national organizations of engineers. He introduced Francis Lee Stuart, past-president of the A.S.C.E. and now chairman of the John Fritz Medal Board of Award. Mr. Stuart outlined the history and purpose of the Medal established in 1902 in memory of John Fritz, of Bethlehem, Pa., one of the great pioneers of America's iron and steel industry, metallurgist, and president of the A.I.M.E. in 1894. Mr. Stuart called the roll of former John Fritz Medalists, three of whom, Ralph Modjeski, J. Waldo Smith, and Ambrose Swasey, were present to do honor to Mr. Jackling. He then introduced George Otis Smith, whose privilege it was to present the Medalist for 1933. Dr. Smith was the senior of the four A.I.M.E. representatives on the Board that last year selected Mr. Jackling for the honor. His speech follows in full.

Jan 1, 1933

By Yushuai Xian, Youjun Tao, Fangyuan Ma

This study compared particle size distribution and density distribution of crushed products for waste printed circuit boards (WPCBs) before and after heat treatment. The crushing process for heat-treated WPCBs is a selective crushing process; more metal is concentrated in the coarse particle range of 1.0–0.5 mm and high density range of 2.8–2.96 g/cm3. WPCBs were separated using the Falcon separator to recycle useful metals. The Box-Behnken module of Design-Expert was used to obtain optimal separation parameters, namely, rotational frequency of 25 Hz, recoil water pressure of 0.025 Mpa and feed speed of 34 ml/s. On this basis, the separation indexes for WPCBs with and without heat treatment were compared. Experimental results show that the recovery effect is better for heat-treatedWPCBs than for thosewithout heat treatment. Comparedwith the non-heattreatedWPCBs, the product grade of heat-treated WPCBs is 1.95% higher, and its recovery is improved by about 14%. Finally, characteristics ofWPCBs before and after heat treatment were analyzed on the basis of stress experiments and scanning electron microscopy (SEM), respectively. Results of mechanical characterization indicate that the stress experiment for non-heat-treated WPCBs has a maximumpressure load of 212 N and displacement of 20mm, but heat-treatedWPCBs only need 140 N stress and 14 mm displacement. SEM shows that copper foil and fiberglass cloth are deformed in different directions and sizes after heat treatment to form gaps, which promote liberation of copper foil and fiberglass cloth.

Sep 10, 2020