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By Lloyd Williams, H. K. Gibbs, William L. Crentz, J. W. Miller

"Reserves This investigation shows that the Poplar Creek is the most important bed in Scott County from a production standpoint. Although the Poplar Creek bed contains the largest reserve, the Big Mary has a larger recoverable reserve. Estimates of reserves also have been made for the Pewee, Red Ash, Windrock, Upper Pioneer, Jellico, and White Oak beds.Known measured and indicated reserves of coal, based on a minimum bed thickness of 14 inches and on 1,800 short tons per acre-foot of coal in place, are estimated to be 143 million tons as of January 1, 1954. Of this total, 74 million tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager for making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.Recoverable reserves of coal are estimated in beds 28 inches and more thick. This thickness is about the minimum now being mined by hand loading onto conveyors in the Appalachian region. The weighted average recovery for all beds in Scott County, as determined by this investigation, is 52.4 percent. This percentage is based on the total thickness of coal in the bed (less partings three-eighths inch or more thick) rather than on the thickness of the coal mined. Based on the weighted average percentage of recovery for all beds in Scott County, the recoverable reserves of coal are estimated to be 39 million tons as of January 1, 1954.Coal Analyses Chemical analyses of coal samples taken for this study show that the coal in Scott County is of high-volatile a bituminous rank except the Upper Pioneer bed, which is shown to be high-volatile B bituminous. The Pewee bed shows typical low-sulfur characteristics. The high ash and sulfur in the Big Mary are characteristic of that bed. The Poplar Creek is moderately low in ash and sulfur in areas where there is no parting in the bed."

Jun 1, 1956

By Timothy C. Siegel

This report presents the results of a synthesis on the design and analysis of ground improvement for liquefaction mitigation. The synthesis included an industry survey concerning the practice of ground improvement for liquefaction mitigation. Participation in the survey was solicited by advertisements in several trade magazines and by e-mail for the DFI membership. The survey participants numbered 150. Their professional roles include consulting engineers, specialty contractors, design engineers, government engineers, and academicians. They represent a variety of geographical areas including North/Central/South America, United Kingdom, Middle East, Caribbean, Hawaii, Japan, India, Egypt, France, Australia and New Zealand. Upon completion of the survey, several professionals in the field of liquefaction and ground improvement were interviewed for them to elaborate on the survey results. The interviews are included in the Appendix of this report. Financial support for the project was provided by DFI and Dan Brown and Associates PC. The concept of the liquefaction mitigation synthesis was developed by DFI?s Ground Improvement Committee in recognition that: (a) The results of recent research and post-earthquake reconnaissance have challenged previously longheld beliefs about liquefaction and associated mitigation techniques, and; (b) The DFI membership and the engineering/construction industry are interested to know if and how engineers and designers are subsequently adjusting their practice in consideration of recent research and post-earthquake reconnaissance. For more detailed information on recent research and post-earthquake reconnaissance, presentations are available from the State-of-the-Art Forum: Liquefaction Consequences and Mitigation that was held in St. Louis in 2012. A commentary of the state-of-practice in ground improvement for liquefaction mitigation (prepared by DFI?s Ground Improvement Committee) is included in this issue of the DFI Journal. The author would like to thank the participants of the survey and especially Mr. Mike Jeffries, Dr. Les Youd, and Dr. Ikuo Towhata for their willingness to share their expertise in interviews. The author also acknowledges Mary Ellen Bruce of DFI, Billy Camp of S&ME, Inc., and Marty Taube of DGI Menard (and Chair of DFI?s Ground Improvement Committee) for their signifi cant contributions.

Aug 1, 2013

By completing a double-track railroad cut-off, involving a large volume of cut and fill, in addition to a half-mile bridge spanning an important French river, engineers in the zone of the Services of Supply have opened up a route by means of which hours of valuable time are being saved in transporting men and materials to combat areas. Its most valuable feature is that it provides a means for by-passing a certain city where several, French railroad lines converge and where, consequently, congestion of traffic has been responsible for delayed train movements. To avoid a double-track turnout, which would have involved a cross-over cutting one of the French tracks, the two track connections of the cut-off are taken off from opposite sides of the French right-of-way. This involved running one of the new lines of the cut-off out from the main line track on a fill to a point where it could be brought back and over the French track on a steel girder bridge. Beyond this bridge the two tracks of the cut-off converge and straighten out in the standard type of double-track construction. The new cut-off is about 5 3/4 mi. (9 km.) long and has required 160,000 cu. yd. of cut (122,329 cu. m.) and 414,000 cu. yd. (316,527 cu. m.) of fill. In the biggest continuous fill a-yardage of 180,000 has been placed; the road-bed in this section-being-about 40-ft. (12 m.) above the original ground surface. The bridge portion of the cut-off, 2190 ft. (667.5 in.) long, is made up of ninety-nine 14-ft. (4.3 m.) timber spans and sixteen 50-ft. (15.3 m.) steel girder spans. This is the longest bridge which engineers of the American Expeditionary Forces have built in France. The timber spans are supported by pile trestle bents, while the longer steel girders rest on clusters of 43 piles. Two pile drivers of the steam-hammer type worked from each -end of the bridge toward the center of the river, while a drop hammer worked westward from the shore end. In this structure nearly two thousand piles 50 ft. or so in length had to be driven.

Jan 12, 1918

IN THE December issue of MINING AND METALLURGY, attention was drawn to the February meeting of the Institute. The plans of the Committee on Arrange-ments have progressed considerably since that date, so that further announcements may now be made. The Mining Methods Committee has definitely arranged for at least three sessions. One of these will be devoted to a discussion of various methods used in sampling large low-grade ore deposits; a second will have for its leading subject underground transportation and mining practice as developed by the Anaconda Copper Mining Co., and the third will be devoted to the coal industry, particularly in reference to the percent-age of economic recovery under various conditions. The Mining Methods Committee will also hold a committee meeting, which will be open to all members, for the purpose of a discussion in reference to the symposium on mining methods which it proposes to hold at an early meeting. The Petroleum and Gas Committee is planning a two-day symposium. A tentative program was printed in the November number of MINING AND METALLURGY, and this, with a few changes, still indicates the plans of the committee. E. L. DeGolyer, vice-chairman of the committee, says Mining engineers and geologists should make every effort to attend the February meeting and hear the symposiums on foreign oil possibilities which have been arranged by the Petro-leum and Gas Committee of the Institute. No such comprehen-sive consideration of this subject as that planned has previously been attempted. This matter is extremely important to all persons who are users of petroleum or its products, and in our present civilization this classification includes every individual, but it is particularly important to the engineer who directs the production and use of power on a large scale. The United States produces currently about two-thirds of the world's oil but consumes more than it produces. We must look .to outside areas for part at least of our petroleum requirements and the future market, because even American oil will be influ-enced largely by the ease and freedom with which this outside supply may be secured. It is important to you to know something of foreign prospects and conditions under which they may be developed.

Jan 1, 1922

By F. J. Longworth

FoR a number of years an intensive study has been made to improve the blast-furnace practice at Copperhill not only as to cost% but to provide a good grade of gas for the acid plants. This study took us back to the fundamentals of successful pyrite smelting; namely, a blast furnace working on a clean sulfide ore, free from fines, and the use of quartz high in silica as a flux. In 1919, the quality of the flux was improved and its effect on the metallurgy was very marked. To improve the practice further, it was necessary to work out some method of treatment for the sulfide fines and the siliceous and refractory ores, other than in the blast furnace. A series of milling tests indicated that these products could be successfully treated by differential flotation, and in 1922 plans were made and a flotation plant built. It was estimated that the flotation plant would deliver to the smelter 40 to 50 tons of concentrates per day; the problem was what to do with these concentrates. It was out of the question to attempt to smelt them in a blast furnace because of the dust losses and because our practice demands a charge free from fines for satisfactory operation. There is no custom smelter in the vicinity to which concentrates may be sold, pending the time when the tonnage will be sufficient to warrant roasters and a reverbatory furnace. Sintering and nodulizing were investigated but neither method fitted into our scheme of metallurgy. A close study of the converter practice was then made to see if some method could not be evolved to smelt this tonnage of concentrates in a converter without preliminary treatment. At that time, the converter installation consisted of two 12-ft. Great Falls converters, which were handling 12 to 14 per cent. matte. The heat balance of the converters working with 12 to 14 per cent. matte was more than sufficient to smelt the contemplated tonnage of concentrates but the mechanical difficulties of feeding fines into the Great Falls converter made the use of this type of converter impractical. While there was no opportunity to experiment with the Pierce-Smith converter, equipped with a Garr gun, theoretically it seemed practical

Jan 1, 1925

By Ørjan Nerland, Torgeir Haugen, Astri Eggen, Kjell Karlsrud

"Ground improvement by the deep dry mixing (DDM) method is used in Norway since the late 1970's. A brief review is given of the Norwegian guideline for ground improvement with DDM issued in 2012, but focus is on practical examples and experiences related to improving the stability of excavations and natural slopes in soft clays. Two examples deal with experiences from 10 to 18 m deep excavations in soft and partly highly sensitive clays, where DDM panels and block stabilization were used to both give sufficient stability against bottom heave and to limit lateral wall displacements. A third case deals with improving the stability of a natural slope in quick clay by installing DDM panels near the crest of the slope. To limit disturbance and excess pore pressures generated during the DDM works, vertical drains were installed in advance in between the DDM panels. This ensured that the excess pore pressures generated by the DDM works (up to 150 kPA) dissipated quickly, which was instrumental to avoid triggering a landslide during the stabilizing works.INTRODUCTIONThe lime column (LC) method developed in Sweden and Japan in the mid 1970's (e.g. Broms and Boman, 1977). Since then, there have been significant developments in Scandinavia and around the world in terms of rigs, mixing machinery and tools, and type of binders used. The method, presently named the ""Dry Deep Mixing"" (DDM) method in contrast to the wet deep mixing methods (WDM) that also have developed significantly over the past decades, e.g. Kitazume and Terashi (2013). The first application of the DDM method in Norway was in the late 1970's to improve the stability of an excavation in quick-clay, then using only lime as binder. Most DDM applications in Norway have also thereafter been to improve the stability of cuts, supported excavations or natural slopes in soft clays. The Norwegian Geotechnical Society (2012) issued in 2012 “Guidelines for design of ground improvement with DDM methods"". The following highlights design issues dealt with. The paper focuses however, on some practical cases where DDM has been used to improve stability of deep excavations and a natural slope in soft and partly highly sensitive clays."

Jan 1, 2015

By R. T. Pepper

DURING an investigation into the effect of heat-treatment on the creep properties of the magnesium alloy ZW1, (1 pct Zn, 0.6 pct Zr), the previously published methods of final polishing were found to be unsatisfactory. A new diamond-polishing technique has been developed to facilitate the study of fine precipitates in this and other magnesium alloys, and is described in this note. The sectioning and coarse grinding techniques are those of Fox and Hall,' and Hess and Cieorge.' Pre- liminary mechanical polishing is done with 6-µ, and 1-µ( grades of diamond compound on 'Microcloth' using a lubricant of 'Hyprez' oil. When the conventional technique is used with a 1/4- µ diamond wheel for the final polishing of magnesium alloys, scratching is likely to result from the abrasive action of the 'Microcloth' nap on the soft metal surface. This problem has been overcome by the use of a cream on the wheel in order to separate the specimen surface from the polishing cloth. To prepare this cream, a solution of 6-ml tri-ethanolamine in 75-ml water is stirred into 12.5 g stearic acid at a constant temperature of 80° to 90°C. The cream is allowed to cool, and is then 'whipped' to a smooth consistency with 100-ml 'Hyprez' oil. Before polishing, the diamond loaded 'Microcloth' is moistened with a few drops of 'Hyprez' oil, then a small amount of cream is worked into the nap. For the best results a wheel speed of 500 rpm should be used for polishing, and the specimen should be held by hand with a light pressure while being rotated in the opposite direction to the wheel. After polishing it is necessary to swab the specimen thoroughly in methylated spirits to remove residual cream and oil from the surface in order to avoid uneven etching and drying stains. Fig. 1 shows the surface finish obtained on a specimen by polishing on a 1/4- ° diamond wheel using the cream, and Figs. 2 and 3 the precipitate observed in ZW1 after polishing, and etching for two seconds in nitric acid 15 pct in ethylene glycol. This new diamond-polishing technique has made a valuable contribution to the programme of metal-lographic research on ZW1 and has become a routine laboratory practice for other low alloy content magnesium alloys.

Jan 1, 1961

By F. R. Hewitt

The methods of mining talc are simple, and in western North Carolina are almost entirely by open cut and quarry. The larger part of the talc of this section lies in various-sized "veins''. inclosed in quartzitic walls, the majority of which have by folding been thrown into a perpendicular position, or nearly so, and the exposed edges of which have been covered by debris from erosion of the mountain above. This covering of loose rocks and earth is from 5 to 25 ft. thick, and in most cases has to be removed because it is difficult to support. Sometimes the covering is heavy enough to "catch" and timber successfully, and in this case the talc can be worked out by the usual method of following the "vein," using stulls for holding up the walk until the vein is worked out, and then allowing the cut or drift to fall in. In some cases it proves more convenient to sink shafts and run drifts, following the talc "veins" until exhausted. The talc deposits of this section are badly broken and faulted both laterally and perpendicularly, and in some cases are found many feet below the level of drainage, necessitating pumping at considerable expense. My own experience in mining talc has been that the chief point is to get a reliable "vein," and that then the mining is not as difficult, or any more so at least, than that of any common ore. If the "veins" are pure talc it is simple; if the talc is admixed with foreign matter, such as tre-molite in excess, or stains of iron or manganese, as is often the case, one had better abandon the deposit. Methods of Manufacture Talc, being a soft mineral, is not difficult to reduce to the condition desired by the trade. Powdered talc is admitted under low duty from France, Italy and Austria, and some is being imported from Asiatic points. Talc is usually ground and bolted in any simple reduction mill. That mined in this section is hand-sorted and the quality that will make good powdered talc is ground for use in the manufacture of talcum powder, cosmetics, etc., while all that is hard enough and has sufficient strength is used for crayons and blanks for gas burners and electrical work, being sawed into the shapes desired. The rest that is clean and pure is ground

Jan 1, 1917

By W. E. Selnes

Introduction In 1938, a survey conducted by the Ontario Mining Association revealed a rather startling fact. Injuries incurred in chute pulling were more numerous than those from any other single cause. This report prompted Mr. W. B. Paton, then Inspector of Mines for Manitoba, to make a similar survey of the mines of his Province. It indicated that, in Manitoba mines, chute accidents ranked second only to those from falls off roofs and sides. Why has the mining industry been so slow to recognize the dangers of chute pulling? A partial answer may be the lack of any systematic classification of accidents according to their real cause. The result has been to attribute to other causes injuries which were a direct outcome of chute pulling, and, indeed, has made it difficult to analyze accidents in the industry as a whole. Perhaps, too, because chutes are generally located in the comparative safety? of the drifts, there has been a tendency to consider the occupation as not very hazardous. Not until enough statistics were obtained on this particular task could it be appraised correctly. The Mining Association's survey has been most helpful, and latterly the industry has done a great deal toward analyzing the causes of chute accidents and toward determining an effective means of overcoming them. Much, however, remains to be done. An effort will be made in this paper to outline methods which have been found successful in materially reducing the number of injuries. Qualifications of the Chute Puller First of all it must be realized that chute-pulling is a specialized occupation. The men require proper training for the job, just as in other mining operations. Care must, therefore, be taken to choose persons whose qualifications fit them for the job. Chute-pulling is an integral part of the general mining operation and cannot be considered as isolated from the tasks of other workers. One of the essential qualifications of a chute-puller is a sufficient knowledge of mining operations to appreciate the effect his work will have on the safety of others in the vicinity. He must take the necessary precautions, by verbal warnings, by placing barricades and signs, or by personally guarding the chutes, to prevent accidents to fellow workers.

Jan 1, 1947

By E. V. Konoplev

Russia is one of the largest manufacturers of potash fertilizers in the world. Processing of potash ores basically is carried out by a flotation way. Potash ores of the Verhnekamsky potash deposit contain sylvite (KCl), halite (NaCl) and water insoluble impurity (up to 8 %), presented silicate- carbonate minerals, easily slimed by ore crushing in rod mills. Ore of some deposit sites, developed by ?Uralkali? Co, contains a significant amount of a carnal-lite (KCl.MgCl2.6H2O). Work practice of flotation potash plants has shown, that increase of car-nallite content in ore leads to increase magnesium ion content in a circulated plant brine (saturated salt solution of potassium and sodium chlorides-sylvite brine) and to deterioration of indicators of ore processing. In the Paper we present results of researches of floatability of various size sylvite and influences silicate-carbonate slimes on sylvite flotation in brines with the various magnesium chloride content. It is established, that with increase magnesium chloride content in the brine mainly decreases the flotation of coarse sylvite and amplifies adverse effect of silicate-carbonate slimes on sylvite flotation. In this connection deterioration of potash ore flotation is caused not only decrease sylvite floatability but also strengthening adverse action of water insoluble impurity on potash flotation. It is shown that the application of frothing agents, which render the stronger dispersive action on the colloidal-micellar structures of amine in the salt solution increases the absorption of collector on the sylvite and improves the flotation of sylvite into magnesium the containing salt solutions. The application of an organic depressor to the greatest degree of decreasing the absorption amine on the slimes and to the smallest degree possessing anionic properties proves to be most effective with the flotation carnallite of the containing potassium ores. It is offered the application the frother on a basis of glycol ethers and organic depressor on a basis of urea-formaldehyde resin. Results of industrial tests developed reagent modes for flotation treatment of ores with the raised carnallite content (to 6 %) on ?Uralkali? Co plant have shown that their application has allowed to receive equivalent indicators potash flotations at change of magnesium chloride content in the brine from 0.7 % up to 2.4 % .

Jan 1, 2014

The great additional clue given to professional books by adequate alphabetical and analytical indexes has been recognized from the beginning in the publication of the Transactions of the American Institute of Mining Engineers The bust ten volumes, edited by Dr Thomas M Drown, the secretary, were provided with indexes, as well as tables of contents Moreover, he included in Vol V (published in 1877), a consolidated index of Vols I to V , inclusive, and, at the triune of his resignation in 1884, he had prepared a similar index of Vols I to X , inclusive, which was published in the following year The indexes of the annual volumes from Vol XI on were made much more extensive than their predecessors Casual mentions, as well as important discussions, were included, the geographical localities of mines of works alluded to in the text were added in the index, and numerous cross-references were introduced, with the purpose of making it easy for the student to discover at once what the Transactions contained, either of thorough treatment or of hints and clues to further inquiry, concerning any topic, locality, or person within their scope In order to extend the advantages of this larger scheme to the earlier volumes a consolidated index of Vols I to XV , inclusive (published in 1888), was prepared by compiling the several annual indexes and introducing additional items for those preceding Vol XI Vol XX , issued in 1892, contained a similar consolidated index for Vols XVI to XX , inclusive, in 1897, a sepal ate index-volume, covering Vols XXI to XXV, inclusive, was published, and on 1902 appeared another for Vols XXVI to XXX These four indexes, for Vols I to XV, XVI to XX, XXI to XXV , and XXVI to XXX, respectively, bound together into a book of about 950 octavo pages have constituted for the last five year s a consolidated index to the Transactions which they cover-with the single difference that the book had to be consulted four times, where a single comprehensive index would require to be consulted but once This disadvantage, however, was relatively small, compared with the great convenience of finding by four trials m one book what would otherwise call for 30 separate searches in 30 books Moreover, the possession of the one might be most useful to a student who did not possess the 30, by indicating to him what they con-

Jan 1, 1907

Paddington processing plant is located approximately 30 km north of Kalgoorlie on the Menzies Highway and is owned by Placer Dome Asia Pacific. First mining was from the Paddington Pit, but in subsequent years the plant has had a history of treating ores from a large number of sources, and has used several different methods to reconcile mining and mill production. Reconciliations are necessary to keep a check on the quality control of mining and grade control processÆs. There is a need to be able to identify and resolve issues that will affect the profitability of the organisation quickly. They are also used to check the quality of the resource/reserve statements, and allow the accurate and timely payment of royalties to stakeholders. During the formation of the Kalgoorlie West operations when Delta Gold Limited and Goldfields Limited merged in 2001, the complexity of reconciliations increased dramatically. The expansion of the scope of reconciliations to include two mills, four underground mines and seven open pits, and ore from one deposit to both mills meant that a revised strategy was essential. A variety of issues have arisen over the years with discrepancies occurring when reconciling both tonnes and grade. There are many ways to approach reconciliations, and in recent times these philosophies have been widely debated on site. A consistent and logical approach that takes into account many different sources of ore, as well as different methods of delivery to the Run of Mine stockpiles is therefore necessary. This would standardise the different approaches taken by the various operations that combined to form Kalgoorlie west. The new method reconciles mill production back to the individual ore sources, and produces reconciled-mined tonnes and grade based on the mill throughput and the change in stockpiles. There will generally be a small discrepancy between the claimed mined tonnes produced (and grades) and the mill production. This needs to be highlighted to the operations concerned if it considered unacceptably large. Paddington mill over the last few years has had up to ten sources of ore each year, and up to 15 different stockpiles being processed during each month from those various pits. This combined with the need for a blended oxide/fresh feed, whilst striving to deliver a consistent (grade and hardness) product to the mill, has meant that reconciliations have been very difficult.

Jan 1, 2003

By D. H. Wertz, R. R. Furlong

Dry room equipment at Donora Zinc Works is of the design which prevailed at the time the plant was built in 1915. It consists of 11 adjoining rooms, each being 99 ft long, 11 ft wide, and 7 ft high and having a capacity for 1040 retorts. Heat is supplied by steam coils beneath the slatted wood floor and by warm air ducts at the ceiling. Drying practice is about the same as that generally followed in the industry except that, under normal zinc furnace operations, the maximum drying time is 45 days. During certain seasons of the year the drying process was seriously affected by varying weather conditions which frequently resulted in a scrap loss of 5 to 7 pct. Because of these unfavorable conditions, which caused uneven drying and strains in the retorts, increased retort failures in the zinc furnaces were recorded. Regulation of temperature and humidity under all conditions appeared to be the logical solution of this problem. Controlled drying had been developed for a number of ceramic products and investigation of several such drying processes in this area revealed favorable results. Along with control of drying conditions and the attendant decrease in scrap losses, plant operators also reported a material reduction in drying time. Another factor affecting the decision to proceed with this development was the drastic change in market conditions for retort clay. Curtailment of shipments from the chief source of supply made it necessary to proceed with blending of other available clays, but quality of these clays was questionable for adequate retort life in the 24 hr furnace cycle. Rapid furnace testing of new mixtures was desirable but impossible with the prolonged drying schedule. Therefore development of a controlled drying process for zinc re- torts offered the solution to the problem of rapid testing of retort mixtures. Description of Process and Equipment The freshly extruded retort is cylindrical in shape, 58 in. long, 9 in. id and has 1 1/8 in. side walls. One end is closed and approximately 2 in. thick. The moisture content of this "green" retort is about 17 pct which means a necessary removal of 30 lb of water per retort. Retorts are set on the slatted floor of the dry room with the closed end down. The controlled drying process depends upon the circulation of a large volume of conditioned air at low velocity. To provide for uniform distribu-

Jan 1, 1950

By George W. Sears

In preparing this symposium, our ambition was to elicit authoritative expression of opinion concerning important selected phases of the industry from men active in it. Responses to requests for contributions were gratifying, especially so in view of the short time available. The generous and cooperative spirit of the industry as a whole is amply evident. Responses were received from the following, who are therefore the true authors of the paper: W. G. Adamson, General Manager of the pershin; Quicksilver Co., Lovelock, Nev.; Dudley Baird, Vice President, Pacific Foundry Co., San Francisco; Walter W. Bradley, State Mineralogist of California; W. D. Burcham, General Manager of the Brewster Quicksilver Consolidated, Terlingua, Tex.; William Forstner, San Francisco; H. W. Gould, of H. W. Gould & Co., San Francisco; Marcus Hulings, General Manager of the Chisos Mining Co., Terlingua, Tex.; Frank J. Katz, Chief Engineer, Division Mineral Statistics, United States Bureau of Mines, Washington, D. C.; Lloyd J. Lathrap, Superintendent, Nevada Quicksilver Mines, Inc., Lovelock, Nev.; W. R. Moorehead, General Manager, New Idria Quicksilver Mings, Inc., Idria, Calif.; F. W. Oakes, Jr., Terlingua, Tex.; C. N. Schuette, San Francisco. Brief Economic History of Quicksilver in the United States Quicksilver ore was first discovered in the United States at what was later the New Almaden mine in California, in the year 1824. Production also began here, but not until 1850, when it was stimulated by the active demand caused by gold-mining operations. Prospecting for quicksilver was active, high-grade ores were found and ample production lowered the price from $100 per flask in 1850 to about half that figure for the greater part of the next 10 years. During the succeeding decade, many new quicksilver mines were found; production increased at a time when the local demand diminished, so that most of the product was exported. The third decade of quicksilver mining in the United States witnessed the development of the pan amalgamation process, particularly in Com-stock silver-mining operations. A suddenly increased demand sent prices soaring, the all-time peak of quicksilver production followed, and the highest price was soon replaced by the lowest one on record. Huge quantities of quicksilver were exported between 1870 and 1880 and exports continued in decreasing measure for three decades to 1910. In

Jan 1, 1930

Although the 71 Minerals operation is now closed down and the operating data presented is almost five years old, it is well worth describing since it was the first heap leaching operation conducted on a primarily silver ore. Tombstone was discovered in 1877 by Ed Schieffelen; and it became one of the most famous mining towns in the West through the stories connected with Wyatt Earp, Doc Holliday, and the Clanton brothers. Like many silver deposits .in the western United States, the Tombstone ores were relatively shallow. Several million ounces of silver were recovered in the relatively few years the camp was active; but mining virtually ceased by the early 1900s and was only continued in a small way until the 19409, a history similar to that of Tuscarora. The 71 Minerals operation was started in May 1975 and continued until late 1978 within the city limits of Tombstone on waste dumps; one was the' Lucky Cuss, Schieffelen's discovery, which had accumulated from the old underground operations. This waste material was mostly less than 50 mm (2 in.) in size, although there was some larger lumps. The grade was about 34 g Ag and 0.5 g Au per mt (1.0 oz Ag and 0.015 oz Au per st). The Tombstone dumps contained approximately 1,000,000 tons. The dumps and patented claims were held by a single owner, Tombstone Development Company, thus sufficient leaching material could be acquired from one source rather than dealing with a number of individuals, as is usual in putting together leaching ventures in old mining camps. 71 Minerals Ltd. was formed and a lease of the properties obtained. A site was selected close to the major mine dumps not far from down- town Tombstone. Pads approximately 90 m (300 ft) wide and 180 m (600 ft) long with an 8-degree slope were prepared using compacted old mill tailings as a base sealant on the pads. Mining was done at a rate of about 2,000 tons per day with a dozer, two scrapers, a front-end loader, and 30 ton trucks. The ore was dumped by the scrapers as it came from the dumps with no screening or crushing in 460 mm (18 in. ) layers and trimmed with the loader. Based on bulk sampling and laboratory testing, the majority of thegold and silver values were recovered within 30 days of leaching.

Jan 1, 1981

By Thomas T. Read

Readjustment of the industrial world to a peace basis after more than 4 years of war will involve many fundamental and far-reaching changes that cannot as yet be clearly foreseen or definitely provided for. Such problems may be subdivided, in the vocabulary of war, into those involving material and those centering about personnel. Of the two, the latter group is the more difficult and obscure, as the factors involved are less clearly understood and the methods to be followed are not yet tested and standardized. When it is said that the market is weak, stocks large, and demand light, every business man understands clearly what is meant and what course he should adopt to adjust himself, so far as possible, to such conditions. But when it is said that the rapid spread of Bolshevism in Europe is a danger to industrial organization in this country, it is difficult to have any assured sense that all that the statement may mean is clearly understood or that the means to be followed to meet such a situation are definitely known. Since Bolshevism is primarily a mental phenomenon and since the rupture it brings about in industrial organization should be prevented, if possible, it is my purpose to restrict this discussion of the activities of the Committee on Industrial Organization to some of its mental aspects, as the chairmen of the sub-committees, from their special knowledge of their own fields, can best set forth recent progress in the lines with which they are especially concerned. The first requisites of success in industrial organization, as in the biological organism of which it is the social counterpart, are unity of purpose and coordinated activity. Typical good and bad examples of this' are the relative parts that the United States and Russia have played in the great war. These two factors are primarily mental, and it is not difficult to view the mental aspects of all problems of industrial organization as the most important ones. Unless we can attain unity of purpose and coordinated activity in industry, the provision of comfortable homes at reasonable rent, the assurance of steady work at good wages, the elimination of industrial accidents, and provision against want in old age or in case of disability will have brought us no nearer to our real goal.

Jan 1, 1919

By W.W. Weigel

The mines of the St. Joseph Lead Co. in St. Francois County, Missouri, form a roughly triangular area of about 45 square miles. Locally this is known as the Lead Belt. The four operating mines in the area at present are the Federal, Leadwood, Desloge, and Bonne Terre, in decreasing order of mine area and daily production. Mining began in 1864 and has been carried on in the district continuously since that time. As a group, the Lead Belt mines now handle 20,000 gal. per min. of water, average head about 465 ft., against a normal daily ore tonnage of 21,200 tons. For a six-day operating week this gives a ratio of 6½ tons of water per ton of ore. Total average pumping in 1931 was about 15,000 gal. per min. Since that time a large area of virgin territory has been opened, much of which has had temporary flush flows. About 75 per cent of the water enters in certain restricted very wet areas. Production figures are given in Table I. The figures by divisions for 1931 and 1941 are not exactly comparable, as there were several transfers of pumping loads from one division to another during that period of time. Geology The, basement formation in 'the Lead Belt area consists of the pre-Cambrian rhyolite porphyry and granite. Overlying this is the La Motte sandstone, of Middle Cambrian age, which offers a good medium for circulation of water. It varies in thickness up to 400 ft. Above this is the Bonne Terre dolomite, approximately 375 fl. thick, which in turn is overlain by the 150-ft. Davis shale. The formations above this, present in the Lead Belt in small areas only, are of minor importance. The ore bodies occur as large, horizontal tabular masses or as long, narrow runs; they are found throughout the Bonne Terre but largely in the lower 150 ft. The rather indefinite contact with the La Motte is a favorite ore horizon. Milling is entirely by open stope and pillar breast systems. To the south, west, and north of the district, sandstone outcrops are few and limited. Heavy faulting bounds The district on those sides and probably there is little if any artesian circulation from those directions. To the east, the La Motte rises to an outcrop area of about 40 square

Jan 1, 1943

By Riki Kobayashi, D. L. Katz

The conditions at which methane and water form solid hydrates have been extended from 4,000 to 11,200 pounds per sq. in. The curve at high pressure had been in doubt because of Villard's report of a critical decomposition temperature. The paper explains the nature of the hydrate curve at high pressure and its dependence on fluid phase behavior. Extropolation of the methane hydrate curve indicates a pressure of 40,000 pounds per sq. in. will cause hydrates to form at a temperature of 100" F. INTRODUCTION The conditions under which natural gases form hydrates when liquid water is present have been studied by several investigators up to pressures of about 4,000 pounds per sq. in. The early work by Villard on hydrates of methane and ethylene13, ethane'', and propane14 included references to critical decomposition temperatures of the hydrates. Villard's work raised the question as to whether the pressure-temperature curve for methane-water hydrate continued above a temperature of 70.7°F. or whether this was the maximum temperature at which hydrates would form. This paper extends the experimental data on methane hydrate to 11,200 pounds per sq. in. A discussion of phase relations in the hydrate region for the hydrocarbons and of the methane-water system at high pressures is included. PREVIOUS WORK Villard suspected that methane hydrates could not be formed at temperatures above 21.5°C. (70.7°F.)la irrespective of the pressure of the liquid-vapor system. However, he was limited in his studies by his apparatus in 1888 to pressures not greater than 300 atmospheres (4,410 pounds per sq. in.) so that there has remained some doubt as to the existence of such a maximum temperature in this region. For the case of ethylene hydrates, however, Villard does specifically state the occurrence of what he terms a "critical temperature for the decomposition of the hydrates"13. Fig. lB shows a pressure-temperature projection of the three-phase locus, hydrate-ethylene rich liquid-vapor (H-L2-V) terminating at the critical locus in which L² and V assume similar properties. Throughout this paper the following phase designations will be used: H for hydrate, Ll for the water rich liquid. L2 for the

Jan 1, 1949

By William H. Sutherland

INTRODUCTION Coal workers' pneumoconiosis and sili- cosis are only two of several diseases which are rlassed as pneumoconiosis. These are respiratory diseases caused by dusts which are inhaled and accumulated in the lungs. The individual particles of dust cannot be seen by the human eye. They are so small that they escape the natural cleansing mechanism of the nose and air passages and make their way down to the terminal air sacs of the lung where they injure the cells and cause the formation of scar tissue. Consequently, if there is exposure to high concentrations of dust over a period of time - usually, a number of years - the amount of scar tissue increases and begins to impair breathing. As a result, the miner develops shortness of breath, coughing and wheezing ad-if exposure continues - this progresses to permanent disability and frequently to death. Death is often due to pulmonary heart disease, the effect of stress on the heart 2s it tries to compensate for the weakened lungs. Specifically, silicosis is an occupational lung disease caused by the accumulation of free silica (quartz) in the lungs. Silicosis is considered the most important form of pneumoconiosis, not only because of its seriousness as a respiratory crippler, but also because of the large number of workers who risk contracting it in a variety of occupations. Quartz is one of the most common substances of the earth's crust, estimated at about 60 percent. Silicosis has been found in coal, metal and granite miners, as well as in other workers, such as sandblasters and pottery makers. Silicosis is also known to predispose the lung to tuberculosis and to increase the chances that a worker will contract chronic bronchitis and emphysema. The seriousness of silicosis was tragically brought to public attention about 50 years ago. During 1932-34, workers were involved in digging a tunnel through rock at Gauley Bridge, West Virginia. While their exposure time was relatively short, they developed silicosis because of the high concentrations of quartz. By 1936, 476 workers had died of silicosis and about 1500 were believed to have the disease (Washington Post, 1982). It is difficult to tell how many coal miners have silicosis. Because x-rays and breathing function tests do not show the difference the type of pneumoconiosis is generally diagnosed by the miner's work history. For example, if a worker

Jan 1, 1986

By G Hancock, J Lowry, T Coulthard, W Erskine, M Saynor

An important part of planning for the rehabilitation of uranium mine sites is the ability to assess the geomorphic stability of the final landform, over time frames ranging from decades to millenia. Depending on the environmental conditions, erosion features such as gullies may incise into containment structures, potentially leading to the exposure and transport of encapsulated radioactive material. Further, erosion may lead to increased sediment loads and the transport of other mine-related contaminants off-site and into downstream waterways. While erosion may be monitored and assessed over the short term (years to decades), the longer-term behaviour (centuries to millennia) of such landscapes is not within any meaningful human management time frame. Landscape evolution models (LEMs) can provide information on soil erosion rates at decadal or centennial scales over large spatial scales, and evaluate the sensitivity of these processes to environmental changes. However, an important issue associated with the use of models is the ability to assess the reliability and accuracy of the model. In this paper, the CAESAR-Lisflood LEM is tested for its ability to predict soil erosion from a series of 30 m × 30 m experimental plots specifically constructed for this purpose on a trial rehabilitated landform at the Ranger Uranium Mine in the Northern Territory, Australia. Model predictions of bedload and suspended sediment loads from the erosion plots were compared with field measured observations collected over four wet seasons from the trial landform. Once calibrated for the specific site hydrological conditions, the predicted sediment yield – specifically, bedload – demonstrated an excellent correspondence with the field data. However, longer-term simulations of ten years identified an exhaustion effect in sediment yield from the landform. These latter results indicate that a weathering function needs to be incorporated into CAESAR-Lisflood to ensure confidence that the CAESAR-Lisflood LEM will be able to correctly predict the long-term evolution of a rehabilitated landform once it has been?constructed.CITATION:Lowry, J,?Saynor, M,?Erskine, W, Coulthard, T and Hancock, G, 2014. A multi-year assessment of landform evolution model predictions for a trial rehabilitated landform, in Proceedings Life-of-Mine 2014 , pp 67–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014