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By Louis D. Huntoon

The Porcupine gold area, located on the Hudson Bay slope of northern Ontario, has produced over $100,000,000 in gold and has paid more than $28,000,000 in dividends, since the first real production in 1912. The character of the ore has been studied by the geologists of the Bureau of Mines of Ontario, the geological staffs of the operating mines, and engineers commissioned to examine properties there. What information the Government has is free to everybody; the geological staffs of the several properties also give to the visiting engineer what information regarding ore deposition they possess, and the author wishes to express his indebtedness to the geologists of the Ontario Bureau of Mines and the staffs of the operating mines for their free discussion of geological questions. This paper is based on the examination of several properties, various petrographic reports, not only on specimens from Porcupine but from elsewhere in northern Ontario, and interviews with Government and mine staff geologists. The petrographic work has been done by Prof. R. J. Colony, of Columbia University. Geological History The geological history of the district may be summarized as follows: The outpouring of great floods of lava accompanied by beds of tuff, flow following flow; the contacts of different flows can be seen in various parts of the camp. This period mas followed by an uplift and the production of the Temiskaming sediments by erosion. Later, dynamic action turned the sediments and underlying lavas on edge; this was followed by the intrusion of igneous rocks—in the Porcupine area the quartz porphyry, which is of such great importance in connection with the gold deposits. Doctor Burrows says: "The intrusions of quartz porphyry have in some way influenced the deposition or location of the gold but it is not likely the porphyry has been the source of the gold-bearing solutions." This statement of Doctor Burrows I indorse. The formation of non-gold bearing quartz veins followed the intrusion of the porphyry. These veins occur along or near the contact of

Jan 1, 1923

By Louis D. Huntoon

The Porcupine gold area, located on the Hudson Bay slope of northern Ontario, has produced over $100,000,000 in gold and has paid more than $28,000,000 in dividends, since the first real production in 1912. The character of the ore has been studied by the geologists of the Bureau of Mines of Ontario, the geological staffs of the operating mines, and engineers commissioned to examine properties there. What information the Government has is free to everybody; the geological staffs of the several properties also give to the visiting engineer what information regarding ore deposition they possess, and the author wishes to express his indebtedness to the geologists of the Ontario Bureau of Mines and the staffs of the operating mines for their free discussion of geological questions. This paper is based on the examination of several properties, various petrographic reports, not only on specimens from Porcupine but from elsewhere in northern Ontario, and interviews with Government and mine staff geologists. The petrographic work has been done by Prof. R. J. Colony, of Columbia University. Geological History The geological history of the district may be summarized as follows: The outpouring of great floods of lava accompanied by beds of tuff, flow following flow; the contacts of different flows can be seen in various parts of the camp. This period mas followed by an uplift and the production of the Temiskaming sediments by erosion. Later, dynamic action turned the sediments and underlying lavas on edge; this was followed by the intrusion of igneous rocks—in the Porcupine area the quartz porphyry, which is of such great importance in connection with the gold deposits. Doctor Burrows says: "The intrusions of quartz porphyry have in some way influenced the deposition or location of the gold but it is not likely the porphyry has been the source of the gold-bearing solutions." This statement of Doctor Burrows I indorse. The formation of non-gold bearing quartz veins followed the intrusion of the porphyry. These veins occur along or near the contact of

Jan 1, 1923

By George A. Packard

WHEN, in April, 1892, the writer began experimenting with the cyanide-process, it had already proved a success in the treatment of tailings, but had not become an important factor as a primary method of ore-treatment. The Livingston, Colorado, mill was running a few small agitators; the Mercur mill, in Utah, was said to be a success, but was " closed down to increase capacity; " and Mr. A. B. Paul, in Shasta county, California, was running ore'through a stamp-mill into leachingvats, using a weak cyanide solution in the battery. Mills had been, or were being, erected in Arizona; on the Comstock lode; and in South Dakota. Some of these never started, and several were shut down or remodelled for other processes. Altogether, the outlook was anything but favorable. Many of these mills were planned to make use of agits tion, and a cyanide solution containing at least 1 per cent. of potassium cyanide was employed. Since then the improvement of the process, both chemically and mechanically, has placed it among the recognized successful methods of oretreatment. Within the past year I have visited a large number of cyanide-mills, and have collected considerable data, of which I publish enough herewith to give an idea of the development of the process and of the methods followed in the principal mills. I would say, however, that nearly all of these plants are experimenting, most of them employing experienced chemists,

Jan 1, 1897

By Masayuki Otagawa

THE mining methods adopted in Japanese mines are less known to the mining world than those of other countries, owing to the geographical remoteness, but they present many features of interest to mining engineers. The Ashio copper mine is at the village of Ashio, in Tochigiken, about 109 mi. (175 km.) from Tokyo by the Imperial Government railroad. The area of the concession owned by the Furukawa Mining Co. is 5000 acres (5023 ha.). The mine was formerly divided into three, viz.. Honzan, Kotaki, and Tsudo, which are distant 3 mi. (4.8 km.) from each other as shown in Fig. 1. However, in 1914, when the writer was general manager, the three mining plants were amalgamated into one with the result of simplifying the working projects and increasing the operat-ing efficiency. The mine was visited-by the Institute party in November, 1911, when Mr. K. Inouye was the general manager. Shortly afterward, the writer was appointed manager, and, in 1915, he was succeeded by Dr. K. Asano. At the end of 1917, Mr. K. Kibe became general manager and, after two years, was succeeded by the present manager, Mr. I. Sugimoto-. For some time Dr. J. Kojima was acting general manager. It is needless to say that the gentlemen mentioned are all members of the Institute, as is also Baron T. Furukawa, president of the company. Since the discovery of the enormous masses, called "kajika" or "bullhead" deposits; which the writer has described elsewhere,' the mining methods have been varied to meet the different conditions presented by these deposits.

Jan 2, 1922

By H. S. Munroe

As elaborate discussion under this heading formed a chapter in one of the reports made by Professor Raymond as Commissioner of Mining Statistics." In a subsequent report? was printed a paper., by Mr. William Main, Jr., of Columbia, South Carolina, containing a theoretical investigation into the effect of the velocity of impact on the effective ditty of stamps. A visit to the Lake Superior copper region last summer suggested an inquiry into the relative efficiency and economy of the enormous steam stamps of the copper-mills, as compared with the results obtained with the cam and tappet stamps commonly used in the West. The atmospheric stomp used at the Phoenix Mill promised to add interest to the inquiry, as giving an example of unusually high speed, this stamp making 160 drops per minute. In introducing his subject Dr. Raymond makes the following remarks, which are quite apropos of the present investigation: "In considering the economical application of stamping machinery, we meet, at the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one arid then another condition of working; but this is seldom possible for such

Jan 1, 1881

By Duk-Won Park, Syd S. Peng

INTRODUCTION More than five years have elapsed since the first shortwall panel was installed in a US mine in 1972. By the latest count, 11 mines have tried the shortwall method on 34 panels. Potentially, the shortwall method (see Figure 1) offers the combined advantages of longwall and continuous mlning. But just like any other mining method, shortwall is not a panacea. It is only applicable under a set of stringent conditions. Coal operators at eight of the eleven mines are satisfied with shortwall mining, though there are only five mines presently producing coal from shortwall panels.

Jan 1, 1981

By H. H. Waller, C. H. Brehaut

At the Jeffrey mine of Canadian Johns-Manville Co. in Asbestos, Que., automatic batched concrete from surface is placed underground pneumatically for distances of 2500 ft directly into forms or to a second placer for greater distances, through 6-in. pipe of high carbon steel. The use of Celite C-4-C in addition to the usual aggregates achieves greater compressive strengths, lowers cost, reduces segregation, and improves workability and placeability results. Each year 25,000 cu yd of concrete are placed without interrupting production and development work in the mine, making possible a cheaper concrete that can be poured wherever and whenever it is needed. In about 90 pct of the underground openings in the Jeffrey mine concrete is necessary to preserve them in their original sizes and shapes for production. In the remaining 5 pct, the greater portion is united with or without steel support. When large quantities of concrete were forecast for underground use at the Jeffrey mine, preliminary and first hand information regarding pneumatic placing was acquired from articles by Bernhardt and Swanson and visits to their respective mines.

Apr 1, 1956

By C. F. Jr. Park

HOG MOUNTAIN is in the north central part of Tallapoosa County, Alabama, about 13 miles northeast from Alexander City. The Hog Mountain Mining and Milling Co. controls 1658 acres of land and is the only company operating in the district. The principal mine workings are in sections 10 and 15, T.24N., R.22E. The region has been visited by geologists many times, has been briefly described in several papers,1 and mentioned in many others. No detailed map of the mine or vicinity has been published. The field work for this report was started in March, 1934, as part of the Public Works reemployment program. About a month and a half was spent mapping both the surface and underground geology. The mine owners and operators have cooperated in every way possible to facilitate the work. N. 0. Johnson, the mine engineer, E. W. Ells-worth, J. E. McCoy and J. G. Englebert have acted as assistants for part of the work. The University of Alabama and the State Geologist's office have aided materially by permitting free use of their libraries and laboratory equipment.

Jan 1, 1935

By T. W. Guy

The increased moisture due to water-spraying for coal dust control is of interest even for mines from which the coal is to be wet-washed before screening, because in many cases wet coal dust materially de- 20-mesh X 0 sizes as pct ROM average ............................... 6.3 pct Range 2.3 to 9.5 pct 20-mesh X 0 sizes as pct 3/8 X 0 sizes average........'...................... 18.9 pct Range 12.7. to 23.9 pct creases the loading efficiency of men and equipment at the faces. It also causes a serious increase in the normal wear and deterioration of all equipment with which it comes in contact. It is important to the consumer if it increases his as-received moisture. No attempt will be made in this paper to cover the entire subject of water-spraying of coal for dust control. It will be confined to discussion and data on (I) percentages of dust in bituminous coals, (2) moisture increases due to spraying for dust control in mines or plants by methods which have proved satisfactory for periods of one to five or more years, and (3) a few suggestions for research. Size and Percentage or Coal Dust The U. S. Bureau of Mines1 classifies as coal dust all bituminous coal passing a 20-mesh sieve (0.0328 in. square opening). The percentage of such dust to be found in ROM coal, of course, varies widely with the characteristics of the seam, and with the methods used in the mining and in the preparation of the coal. ROM screen analyses of 12 U. S. coals selected at random from personal files given in Table I show: A few other screen analyses examined indicating 40 pct or more of 20-mesh X 0 dust in 3/8 in. X 0 sizes were not included because of uncertainty that they were representative. The number of results in Table I is not sufficient to give a reliable estimate of the average, or of the range to be expected, but it indicates that in every case the coal dust is a relatively large percentage of the total ROM coal, and, of course, a progressively larger percentage of resultants as the larger sizes are separated for marketing.

Jan 1, 1949

By J. V. Gluck

In the present paper," as in earlier publications, V1'2"1 the authors present experimentally obtained relations for the free energy of solution of oxygen in various metals as a function of temperature. The relations are linear and given in slope-intercept form. The authors give values for the "probable error" of the slope and intercept, citing Birge's method17 for obtaining these quantities. Birge discussed these methods as early as the period 1929-32.25726 In Ref. 25 the probable error is defined as "the numerical value which the true error is as likely to exceed as not", i.e., 50 pct probability. Ref. 26 is even more detailed and includes a lengthy discussion of the applicability of the Gaussian distribution to experimental data. However, the use of the "probable error" has come under some question. For example, Ezekiel'~ states that "the use of the probable error tends to make the results appear rather more accurate than the standard error". Moroney28 stated (in 1951) that "the term 'probable error' was used in former times to denote 0.67450 (50 pct confidence using the normal distribution)....the term, a poor one, is now very much obsolescent. It has been said that 'it is neither an error nor probable' ". Bennett and Franklin in 1954" in discussing statistical confidence levels mentioned that "the customary use of the 5 and 1 pct levels is not completely a matter of chance; these levels probably represent a balance between the desire to be correct and the desire to be specific. Also in most people's minds the borderline between something that could possibly happen and something that is not likely to happen is somewhere in this region. Certainly 5 or 1 pct confidence limits are to be preferred to limits such as the 'probable error' which has only a 50/50 chance of including the correct value." It may readily be seen that the 95 pct confidence level, which is given by 1.960 (assuming large sample size), thus corresponds to approximately three times the "probable error". Indeed, limits of one standard deviation correspond only to about 68 pct probability. Even if we triple the tolerances given by the authors in the equations of their Table 111, the deviations do not become excessive and would not detract from their excellent results. It could then be said with a high degree of confidence (95%) that the precision of the slope and intercept values is about *3-5 percent of their absolute levels rather than the 1-2 percent implied in Table 111. This is then compatible with an earlier suggestion of Gokcen~' of a probable accuracy of 5 pct in dissolved oxygen measurements by the technique employed. Alternatively, the authors could have

Jan 1, 1967

By Arthur Lake

Within the past few months I have had occasion to visit and examine the area of country in Gunnison county locally called the Gold Belt and extending from the Cebolla river on the west to the head of Taylor Park and the Sawatch range on the east. The region including the "belt" may be hided topographically into two parts, a northern and a southern one. The former is characterized by lofty mountains and deep canons, with occasional parks and wide valleys. Most of it is included in the granitic system of the Sawatch range, with local patches of the Palaeozoic sedimentary rocks, more or less traversed by great bodies of porphyry and other eruptive rocks. The southern portion, on the other hand, is characterized by comparatively low, rounded hills of schist and sahistose gneisses, underlain by coarse, massive granite, which outcrops locally in small, and sometimes in large, patches. These hills also sometimes form table-lands by reason of overflows of lavas, such as andesitic breccia, rhyolite, trachyte and basalt. The leading geological feature is that of a schistose area of width and extent unusual for Colorado. These schists and gneisses are of pre-Cambrian age; but whether assignable to the Algonkian or to some older system has not been determined. The granite which occasionally outcrops from beneath these schists is, I think, of true eruptive character, since its mode of occurrence indicates a once molten, or at least highly viscous or plastic, condition. Thus, we may observe, included in its mass, numerous fragments of schist, almost like a coarse, volcanic breccia. Again, at its immediate contact with the schists, which often stand vertically upon it, the pediments of the latter are fused into the granite, and granite tongues and veins run up amongst the schists, as only a molten or viscous

Jan 1, 1897

E L. DEGOLYER, our new president, though a petroleum geologist by profession, has always s been associated with mining, for soon after his birth at Greensburg, Kan., on Oct. 9, 1886, his parents moved to Joplin, and when he went, in the course of time, to the University of Oklahoma, he intended to follow his course there with another at a mining school. He became a field assistant in the U. S. Geo-logical Survey, however, while still an undergradu-ate, and after field experi- ence in Montana, Wyoming, North Dakota, Colorado and Oklahoma, he went to Mexico as geologist for the Mexican Eagle Oil Co. This was in 1909, and as a result he was unable to complete his work for his degree until 1911. In Mexico, he located the Potrero de Llaño No. 4, one of the world's largest oil wells, and also the dis- covery well in the Naran- jos pool; and the Colorado School of Mines conferred the honorary degree of : Doctor of Science on him in 1925. On his return from Mexico, he engaged in the consulting business, specializing in financial ap- praisement, the Union and Marland companies being among his clients. In 1919, he organized the Amerada Petroleum Co., with the backing of Lord Cowdray. Last year, control of the company was purchased by an American group, headed by Dillon, Read and Co. Mr. DeGolyer is n o w president of the company. He is also vice-president and general manager of the Rycade Corp, the Rycade Oil Corp., and president of the Geophysical Re-search search Corp. The l a t t e r represents the practical appli-cation of his inter-est in the use of the torsion balance in the locating of salt domes, in which he has pioneered, the Nash dome being the first oil field in America actually brought into production by these methods.

Jan 3, 1927

The Climax Molybdenum Company' s newest operation is the Henderson project, which is located on the east side of the Continental Divide. Ore reserves are estimated at more than 300 million tons at a grade of 0.49% MoS2. For mining the ore a modified panel caving system is used. The ore is transported to the Henderson mill on the west side of the Continental Divide on a 42 in. (1.07 m) gauge railroad through 9.6 miles (15.4 km) of tunnel and 4. 8 miles (7.7 km) of surface track, a total distance of 14.4 miles (23. 2 km). Each train consists of 30 ore cars with capacity of 22 st (20 mt) of ore or 660 st (599 mt) per train. The unmanned trains operate completely automatically. At the 54 in. by 84 in. primary gyratory crusher, the bottom dump ore cars pass over a dump scroll to discharge at a maximum rate of 100 st (91 mt) per minute. Dumped ore falls onto a rock box before passing over a 17 ft long by 46 ft wide (5. 2 m by 14 m) grizzly set at a 40° angle with bar spacings of 7 ½ and 8 ½ in. (191 mm and 216 mm) openings. An estimated 30 to 50% of the ore (which at times is wet and sticky) passes through the grizzly. The operators report that a shallower angle on the grizzly, perhaps 35º to 37º, would have been sufficient and would have prevented impact on the back of the crusher pocket by large boulders. This pocket as well as the crushed ore pocket under the crusher is lined with AR plate. The accompanying drawings show a "future splitter" and the operators are planning the installation of this unit to prevent impact and subsequent damage to the crusher spider. Crushed ore at an 8 to 9 in. (203 mm to 229 mm) size joins the grizzly undersize in the pocket beneath the crusher. This pocket is sized at 660 live st (599 mt) so that it will accept an entire trainload of ore. Crushed ore is removed from the pocket by a four-speed, 84 in. (2. 1 m) apron feeder operating at 9.6 to 29. 3 fpm (2.9 to 8.9 mpm). A 60 in. (1.5 m) takeaway conveyor operating at 480 fpm (146 mpm) delivers the crushed ore to a 58,000 st live and 193,000 st total (52,600 and 175, 100 mt) open stockpile under an A -frame supported tripper gallery. Impact idlers on the takeaway conveyor under the apron feeder discharge are mounted on wood blocks for a cushioning effect and ripped belt detecting bars are located behind each impact idler. The conveyor tunnel is of corrugated and galvanized steel construction rather than concrete. The concrete crusher enclosure is circular in design from its lowest level at elevation minus 110 ft 4 in. (minus 33. 6 m) to elevation

Jan 1, 1978

By J. G. Bradley

On February 1, 1971, United States Steel Corporation, Lorain Works began operation of its first BOP facility equipped with a partial combustion gas cleaning system.- This shop consists of two 220 ton vessels. Figure I schematically describes this partial combustion gas cleaning system and highlights the necessary features for it-s safe and efficient operation. Waste gases are drawn into the membrane hood by a 2250 H.P. induced draft fan and are first quenched by the six inch bull nozzle at the top of the hood. Larger solid particles are separated from the gas in the quencher venturi and final scrubbing takes place in the P-A high energy venturi scrubber before the cleaned waste gas is burned in the flare stack. Scrubbing water is routed through a cyclone separator and then cycled into one of two 100' diameter thickeners. Underflow sludge which averages 20% solids is dewatered by 100 H.P. centrifuges. The clear overflow from the thickeners is recycled first to the P-A venturi and then to the quencher before returning to the thickeners.

Jan 1, 1972

By T. A. Rickard

It has been stated, by Sir James M. Barrie, that "the man of science appears to be the only man who has something to say, just now-and the only man who does not know how to say it". The friendly jibe of the novelist contains enough exaggeration to make it humorous to the followers of Huxley and Spencer; but could any litterateur poke similar fun at the exponents of the avowedly utilitarian branches of science-the men of technology-without suggesting an unpleasant truth? Indeed the engineer does bungle language deplorably. He makes a fetish of efficiency, yet he shows no regard for the effective use of one of his most important tools-the pen; he believes devoutly in accuracy, yet he employs an instrument of precision as carelessly as a small boy handles a gun. This inconsistency may be due to causes such as were indicated by the Academic Senate when it undertook to explain the defective writing of the; students in this university.* The Senate suggested that the student is "constantly subjected by his environment to the unedifying influence of myriad examples of poor English", and that he is also affected by "a certain public prejudice against correctness of expression ". With these statements most of us will agree. Our local newspapers, for instance, tend to spoil the student's taste for good English; later in life, as an engineer, his daily contact with illiterate men inclines him to careless speech and slovenly writing. As

Jan 1, 1931

By H. S. Munroe

AN elaborate discussion under this heading formed a chapter in one of the reports made by Professor Raymond as Commissioner of Mining Statistics.* In a subsequent report- was printed a paper, by Mr. William Main, Jr., of Columbia, South Carolina, containing a theoretical investigation into the effect of the velocity of impact on the effective ditty of stamps. A visit to the Lake Superior copper region last summer suggested an inquiry into the relative efficiency and economy of the enormous steam stamps of the copper-mills, as compared with the results obtained with the cant and tappet stamps commonly used in the West. The atmospheric stamp used at the Phoenix Mill promised to add interest to the inquiry, as giving an example of unusually high speed, this stamp making 160 drops per minute. In introducing his subject Dr. Raymond makes the following remarks, which are quite apropos of the present investigation : "In considering the economical application of stamping machinery, we meet, at- the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such * Mineral Resources West of the Rocky Mountains, 1871, p. 380. †- Mineral Resources West of the Rocky Mountains,, 1873, p. 345.

Jan 1, 1881

By Paul Cook

THE ore deposit of the Buckhorn Mines Co., Buckhorn, Nev., is peculiar in being a shallow kaolinized mass of material with basalt walls, and having apparently no direct connection with any of the usual gold-bearing rocks. The average ore contains 16 per cent. waiter of hydration, and the cyaniding of this hydrous clayey material offered unusual difficulties as compared with the typical gold quartz ores of Nevada. The orebody was thoroughly developed; then the mill was built according to the latest cyanide .practice, with such changes as were thought to be demanded by the peculiar nature of this ore. Upon starting the mill, the ore proved more difficult to handle than had been anticipated. It is hoped that an account of how these difficulties were met may prove of interest to anyone having a clayey ore to handle and to the profession in general.

Jan 9, 1916

By W. P. Rawles

In the foreword by C. K. Leith, Chairman of The Mineral Inquiry, it is pointed out that the ordinary mineral production tables do not show the commercial control, and that some knowledge of the situation is desirable as a background for the consideration of problems involving mineral raw materials. The report consists principally of tables, accompanied by a brief text, giving the production and an analysis of the control, according to nationality, of 18 minerals: aluminum, chromite, copper, iron and steel, lead, manganese ore, mercury, molybdenum, nickel, nitrates, petroleum, potash, silver, sulfur, tin, tungsten, vanadium, and zinc. For the most part, the production figures for 1929 and the latest figures for reserves have been used. When feasible, the control has been shown at the various stages of production; mining, smelting and refining. American capital was dominant in the production of 10 mineral commodities, including six of the most important; British capital, in four instances; while Spanish, German, Chilean or Chinese interests cach led in the control of one. British, French, German, and Dutch capital occupied second place in the control of most of the important minerals. Between two-thirds and three-fourths of the world's mincral production is controlled by British and American capital.

Jan 1, 1934

By Robert S. Shoemaker

At this Symposium on Gold which is sponsored by The Metallurgical Society of AIME and the International Precious Metals Institute many distinguished authors will present the latest developments in the metallurgy of gold and in operating practices at mines and in refineries. It seems appropriate then, as the introduction to this volume to recall some of the history of gold and the metallurgical developments which have been accomplished, especially during the past 100 years and some of the people who have contributed so much to the metallurgy of gold. Of all the elements gold has been the most sought after since the earliest times. Perhaps the quotation from Virgil's Aeneid best describes man's desire for gold but Pliny the Elder also put it very well when he wrote in 79 A.D. that "Gold is the first of man's follies, silver the second". This quest for gold has markedly influenced man's history and through the efforts of the early philosophers and alchemists to turn base metals into gold the foundations for modern chemistry were laid. The pages of history literally teem with references to gold. Gold is the first metal mentioned in the Bible and was the source of Croesus wealth as well as the death of King Midas whose touch turned everything into gold. And of course almost everyone has heard of Jason's Argonauts and the golden fleece. They are the subject of one of the many drawings in Agricola's De Re Metallica published in 1556. The Argonauts were probably prospectors seeking the source of the placers in the region near-the Black Sea. The time was about 1200 B.C. and the placer miners recovered gold by trapping the particles in sheep's fleeces placed in sluices. After drying, the fleeces were shaken to recover the gold. Gold is not hydrophilic, or wetted by water and thus the oils in the wool aided in collecting the particles. Here we have perhaps the earliest reference to surface chemistry and the basis for concentration of gold by flotation.

Jan 1, 1984

By K. K. Kohli, S. S. Peng, R. E. Thill

Introduction Since the adoption of the Surface Mining Reclamation and Control Act of 1977, which mandates that surface subsidence be an intergral part of the underground coal mine design, there has been a sudden rise of demand on guidelines for minimizing surface subsidence and its associated structural damages. Unfortunately there is no sufficient amount of systematic subsidence data to fill such a gap, although considerable research has been devoted to the subsidence induced damages of surface structures in the past. However, it was said that many surface subsidence surveys have been performed and monitored by coal companies during the past twenty years, and that it will be a great source of information for subsidence engineering design if they can be collected and assembled together. An effort was therefore initiated in the Department of Mining Engineering, West Virginia University, under contract with the U. S. Bureau of Mines in December 1978 to contact each individual coal company in the Northern Appalachian Coal Field for any surface subsidence survey data. After 10 months' survey, the data collected include: 17 longwall panels and 2 room and pillar sections. The data in each panel and section cover the complete set of subsidence survey raw data, underground mine layout maps, surface topo maps, geological loggings showing the stratigraphic sequences and thickness of the overburden, and if available, locations and types of surface structures. On-site visits were followed to study the surface terraines and structures. Interviews were conducted with the owners of the surface structures in most cases about, if any, the history and characteristics of damages. Most subsidence surveys started with the first panel and ended with the second or sometimes, but rarely, the third panel. The first panel may be located in a virgin area but frequently it was adjacent to (on the tailentry side) a mined-out room and pillar section. It must be noted that all of the subsidence data is restricted only to the amount of vertical subsidence and that the horizontal displacement measurement was completely ignored. Primarily due to the fact that vertical subsidence is the most striking feature in a subsidence trough, which is mistakenly considered to be the only critical contributor to surface structural damages, and that a horizontal displacement survey is much more complicated and time-consuming.

Jan 1, 1981