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By W. G. Woolnough

Production of oil in Australia is negligible at present. A very small quantity of crude is being recovered from lean pumpers in Victoria, and a little activity is evidenced in Queensland, where two new wells were sunk during 1934. One of these, at Warooby Creek near Roma, obtained a noteworthy gas flow, but no oil production has been recorded. Geological investigation is going on in Western Australia, but no drilling activity is apparent. The "boom" in oil prospecting came to an end when the wave of depression swept over the country, and the investing public turned its attention actively towards gold. There is great activity in gold prospecting at present. I still maintain as strongly as ever that the prospects of obtaining flow oil in Queensland, Western Australia and Victoria are good, and that really scientific methods must ultimately succeed. Active and excellent geological work is being carried out in the Mandated Territory of New Guinea, and it is reported that drilling is likely to be undertaken next year. Matters in Papua are at a standstill. The question of extraction of oil from the oil shales of New South Wales and Tasmania is perennially active, and attempts to exploit this source commercially are renewed from time to time. Hydrogenation of coal is also receiving a good deal of attention.

Jan 1, 1935

By F. L. Grammer

In these day, when anthracite is less extensively used as a blastifurnace fuel than it was a generation ago, and managers endeavor to maintain regular and known ore-mixtures, the " freezing " of tuyeres, cinder-notch or iron-notch is infrequeut; and, consequently, the oil-burner or " kerosene blowpipe "* is seldom employed; and furnace-foremen have, to a considerable degree, forgotten their former cunning and persistency in the use of the drill and sledge. Still, in starting new or abandoned plants with untrained labor, and in running some of our large 100-ft. furnaces, slips, resulting in very cold furnaces, may occur, even under experienced managers. During my superintendence of the Cleveland, O., blast-furnaces, such a misfortune, owing to a dearth of trustworthy foremen, was experienced; and our electrician, Mr. Thomas Martin, proposed to open the tuyeres and cinder-notch by means of the heat of the electric arc. We have heard that the surface-cracks or marks developed in rolling heavy plates have been closed by electric welding, as by a soldering-iron, and also that an electric burner has been employed at some German blast-furnaces; but the experiment was quite novel to us; and I think it constituted one of the first, if not the very first, successful application of this device, for the purpose named, in the United States. †

Jan 1, 1902

THE metal iron has physical arid chemical properties which are some- what different from those of steels, but a knowledge of the pure metal is a useful starting point in studying the behavior of steels. Solid iron exists in two different crystalline forms, called alpha (a) and gamma (?) iron the former being the ordinary form at room temperature. When heated above the "A2 point," 769 C (1416 F), the metal becomes nonmagnetic, and at the "A3 point," 911 C (1672 F), it undergoes a change in crystalline form to become gamma iron. 111 the range 769 to 911 C, it is sometimes called beta (ß) iron to distinguish it from the magnetic alpha, but the two are identical in crystal structure. When gamma iron is further heated to 1392 C (2538 F), it changes into delta (d) iron, which is identical with beta or nonmagnetic alpha iron. Pure iron melts (in an inert atmosphere) at 1536 C (2797 F); the melting point is generally lowered by alloys or impurities. PHYSICAL AND THERMAL PROPERTIES OF IRON Many of the properties of iron undergo abrupt changes at the transition temperatures.1 For example, in heating through the A3 point, a sudden shrinkage in volume occurs. Similarly, melting is attended by sharp physical changes such as an increase in volume. Table 16-1 contains a summary of the measured physical properties of pure iron at several temperatures. Usually the properties change smoothly with the range of stability of a given form, but this is not always true. For ex- ample, the specific heat reaches a sharp maximum at the A2 point al- though no transformation occurs. (See Fig. 14-1.) Solvent Powers of Liquid Iron. Liquid iron is capable of dissolving most of the other metals and many nonmetallic elements as well. Of the metals that are liquid at the melting point of iron, only lead, silver, and bismuth refuse to dissolve to an appreciable extent. Table 16-2 contains a list of the common elements classified with respect to their solubility in liquid iron. Those which are very soluble or practically insoluble require no further discussion, but several of the nonmetals that are gases and exhibit limited solubility are of considerable importance to us and merit more detailed consideration.

Jan 1, 1964

By Paul Billingsley, Augustus Locke

Certain adequately developed mining districts give complete three-dimensional patterns of ore bodies as clusters rising from roots in basement rocks with details controlled by structure of cover rocks. Examples are Goodsprings, Tintic, Bisbee, Leadville, Hedley, Eureka, Ely and Goldfield. In these and others the controlling structures in both basement and cover rock are elements of the neighboring regional structure and have been produced by rock movements in harmony with continental adjustments, which are usually steep tear faults in basement and thrust crumples in cover. Invariably the structures and movements in the districts have long geologic history and result from intersecting or superimposed deformations of different ages. Salt Lake districts show intersecting Uinta and Cordilleran elements; Colorado districts show intersecting pre-Cambrian and Tertiary elements, and Bisbee shows Tertiary superimposed on fina1 Paleozoic folding. Thus the position of districts has been determined by the patterns of North American orogenic belts, which make crossroads in Rocky Mountains and blocks of superimposed deformation in Sierra Nevada, northwest Coastand Canadian Coast Ranges. Essential function of repeated deformation is to strengthen rock, as from shale to slate to schist to gneiss, and thus make it competent to carry channels to depth with or without addition of intrusives. The essence of a mining district is the presence of such competent rocks with long-lived, deep, penetrating breaks reopened to permit passage of heat and associated products from depths to surface. It is suggested that melts such as magmas; metamorphism up to and including granitization; alteration, such as orthoclase-quartz or quartz-sericite or garnet, and also mineralization, may all be by-products of such heat escape along channels made by tectonic forces at specific foci. Magnitudes of Districts (Fig. 1) Any synthesis of ore deposits must deal with comparable units. Ore deposits are innumerable, but great ore deposits, commercially important for a generation or more, are few. The bulk of metals has come from districts of the first and second magnitudes (over $1,000,000,000 and over $250,000,000, respectively), and of these the United States and adjacent provinces of Canada and Mexico contain only 28, of which 9 are first magnitude: Butte, Coeur d'Alene, Bingham, Bisbee, Sierra Gold, in the West; Tri-State, Southeast Missouri, Michigan copper, Sud-bury, in the East. Another 28 or 30 districts are of third magnitude (over $50,000,000).

Jan 1, 1941

By Augustus Locke, Paul Billingsley

Certain adequately developed mining districts give complete three-dimensional patterns of ore bodies as clusters rising from roots in basement rocks with details controlled by structure of cover rocks. Examples are Goodsprings, Tintic, Bisbee, Leadville, Hedley, Eureka, Ely and Goldfield. In these and others the controlling structures in both basement and cover rock are elements of the neighboring regional structure and have been produced by rock movements in harmony with continental adjustments, which are usually steep tear faults in basement and thrust crumples in cover. Invariably the structures and movements in the districts have long geologic history and result from intersecting or superimposed deformations of different ages. Salt Lake districts show intersecting Uinta and Cordilleran elements; Colorado districts show intersecting pre-Cambrian and Tertiary elements, and Bisbee shows Tertiary superimposed on fina1 Paleozoic folding. Thus the position of districts has been determined by the patterns of North American orogenic belts, which make crossroads in Rocky Mountains and blocks of superimposed deformation in Sierra Nevada, northwest Coastand Canadian Coast Ranges. Essential function of repeated deformation is to strengthen rock, as from shale to slate to schist to gneiss, and thus make it competent to carry channels to depth with or without addition of intrusives. The essence of a mining district is the presence of such competent rocks with long-lived, deep, penetrating breaks reopened to permit passage of heat and associated products from depths to surface. It is suggested that melts such as magmas; metamorphism up to and including granitization; alteration, such as orthoclase-quartz or quartz-sericite or garnet, and also mineralization, may all be by-products of such heat escape along channels made by tectonic forces at specific foci. Magnitudes of Districts (Fig. 1) Any synthesis of ore deposits must deal with comparable units. Ore deposits are innumerable, but great ore deposits, commercially important for a generation or more, are few. The bulk of metals has come from districts of the first and second magnitudes (over $1,000,000,000 and over $250,000,000, respectively), and of these the United States and adjacent provinces of Canada and Mexico contain only 28, of which 9 are first magnitude: Butte, Coeur d'Alene, Bingham, Bisbee, Sierra Gold, in the West; Tri-State, Southeast Missouri, Michigan copper, Sud-bury, in the East. Another 28 or 30 districts are of third magnitude (over $50,000,000).

Jan 1, 1941

By Leo J. Vogel, E. D. Hummer

INTRODUCTION by E. D. HUMMER An efficient refuse-disposal system is a necessary part of the modem cleaning plant. The large-scale refuse system and disposal area, engineered for the lifetime of the plant, has become more important due to the greater tonnages of refuse produced from increased quantities of mechanically mined and prepared coal. Laws and increased government regulations have affected the design and operation of disposal systems. THE EFFECT OF MINE AND PLANT OPERATION Refuse disposal starts at the mining face. The mining system, the type of roof support, the machinery used, and the degree of discipline at the face contributes to the amount and type of refuse that must be removed through the disposal system. Economies gained through modification of the mining system or mining machinery may be partially offset by increased dilution of the mined coal with impurities from associated rock formations. In some cases the change in the mining system and equipment has reduced the dilution. In all cases the ratio of impurities that must be removed from the raw-coal feed to the plant not only affects the maintenance and operating costs of the plant, but greatly affects the design of the refuse disposal system. The design of a mine and plant should include the location and the estimated capacity of the disposal areas for the life of the property or plant. Complete evaluation of the disposal system and an estimate of its annual cost of operation over the life of the property or plant should be incorporated in the plant and mine evaluation. Plant design should be as simple as possible, consistent with the efficient production of clean coal. Material transfer points, crushing, screening and pumping operations should be kept to a minimum to reduce degradation and the subsequent increased difficulty and cost of refuse removal. The maintenance of good process control by operating management will result in a minimum of misplaced material in both refuse and clean coal. Reduction of misplaced float material in the plant refuse is an important factor in preventing combustion in the refuse storage pile. THE REFUSE DISPOSAL AREA Combustion in refuse piles occurs when air enters the pile in sufficient quantity to support oxidation. At certain rates of air in-filtration, the heat produced by the oxidation process is not dissipated and temperature rises.

Jan 1, 1968

By E. D. Gardner

Apparently the widespread agitation for the codification of our mining laws has had its effect, and it is quite possible that Congress will take up the question during this present session. The greatest objection to our present statutes pertaining to metalliferous deposits seems to be directed against the law of the apex. Those who are not in favor of changing this law are very far in the minority and they apparently realize that it is useless to urge its retention. Next in importance to the repeal of the law of the apex, seems to be a widespread advocacy for the repeal of the law requiring discovery of mineral before a valid location of a mining claim can be made. To a lesser extent there appears to be a desire to have the law changed so as to allow patent for claims without mineral discoveries. The purpose of this article is to review the arguments in favor of the proposed change of the discovery requirement, to show some of the evils that may be expected to result therefrom, and to consider whether a system may be devised to correct the undesirable features of the present law in this respect and at the same time not expose the mining fraternity and the general public to the evils which would result from the repeal of this fundamental requirement. Under the law as at present framed, the validity of a mining location is dependent upon the fact of discovery of mineral within the boundaries of the land claimed. " * * * but no location of a mining claim shall be made until the discovery of the vein or lode within the limits of the claim located" (Sec. 2,320, U. S. Rev. Stat.). All authorities agree that discovery is the source of the miners' title. Lindley, in his valuable work on Mines (3d Ed., Sec. 335), lays down the rule in part as follows: "Discovery is the initial fact. Without that no right can be acquired. * * * Such discovery must precede the location, or be in advance of intervening rights. The proof of recording and marking a claim will not authorize the court to presume a discovery." As is well stated by the U. S. Supreme Court in Erhard v. Boaro (113 U.S. 536):

Jan 1, 1917

By E. L. Bruce

The district of Patricia, in the province of Ontario, lies northwest of the Albany River and extends northward to Hudson Bay. Formerly this was the unorganized district of Keewatin, the southern part of which was divided in 1912 between the provinces of Manitoba and Ontario. The interprovincial boundary now runs north from Lake of the Woods for 275 miles and thence northeast 375 miles to Hudson Bay. This district is comparable in size to all the older part of Ontario south of the Canadian Pacific Railway east of Lake Huron—thus it is roughly one-third of the whole of the present provincial area. The central part of this great triangle is one of the least accessible parts of Canada. From it streams flow southward to the English River, southeastward to the Albany, northward to Hudson Bay and the Hayes River, and westward to Lake Winnipeg. None of the streams is large and canoe travel is not easy. The only industry it has ever had is the trade in furs. Until the development of the airplane on a commercial basis, the only means of travel was by canoe or dog-train. There is not a mile of railway in the whole district. The two areas to be dealt with lie in the southwestern part of Patricia. Red Lake is 50 miles east of the Manitoba boundary and 75 miles north of the transcontinental railway from Cochrane to Winnipeg. Woman Lake is 50 miles farther east and slightly farther north. The late Dr. D. B. Dowling, of the Geological Survey of Canada, visited Red Lake and spent some time there during his exploration survey from Lac Seul to Berens River in 1893. He also visited the Woman Lake basin during the same journey, but his examination of it was much less detailed, the great area covered by him during the one field season making it impossible to make more than a hurried reconnaissance. Some prospecting in the Red Lake district followed Dowling's exploration, but the distance from railway was too great for any systematic work to be done. In 1922, following the usual plan, the Ontario Department of Mines made a geological reconnaissance of the English River, following :in instrumental survey of that river and its lakes by the Department of Lands. A side trip was taken to examine the rocks of Red Lake described

Jan 1, 1928

By David R. Mitchell, Ernest M. Spokes

MINING ENGINEERING, page 373, March 1958, vol. 211) S. C. Sun: This article by Spokes and Mitchell deserves high commendation. For many years mineral dressers have been at a loss to explain the variation in magnetic susceptibility of the same mineral species obtained from different localities. In fact, they do not even have a list of accurately measured data on the specific magnetic susceptibility of weakly magnetic minerals to consult. Experience as a university teacher has firmly convinced me that the average student has more difficulty in acquiring a satisfactory knowledge of magnetism than of any other branch of mineral dressing. This is almost entirely because the subject has been treated far too much from a strict practical standpoint and far too little from a fundamental one. It is no exaggeration to state that almost all the published theoretical discussions are based on the experimental results of manufactured chemicals and alloys, but not of naturally occurring minerals. In an attempt to remedy this state of affairs, the author of this article not only set up a new magnetic balance in the Department of Mineral Preparation of The Pennsylvania State University, but also performed work of fundamental value, thus pointing the way to further research. This is evidenced by the fact that an investigation of the magnetic susceptibilities of manganese minerals was recently completed by S. G. Watt under the direction of David R. Mitchell, now acting dean of the College of Mineral Industries of the Pennsylvania State University. D. J. Cook is studying the magnetic susceptibility of titanium minerals under my supervision. It is hoped that our research program can be continued for several years and that similar investigations will be initiated at other universities and research institutions. Ernest M. Spokes (author's reply): The discusser has touched the heart of a pedagogical problem in the field of minerals beneficiation—students do not understand magnetism and, as a result, neither do the graduate engineers. Only recently has the average course in engineering physics started teaching the fundamentals of magnetism, as they are understood in modern physics, in addition to the classical treatment of the mathematical aspects of magnetic phenomena. It is to be hoped that this increasing instruction in fundamentals will improve our understanding and inspire research to determine more of the basic magnetic data that are essential if we are to see improved methods of separation by magnetism.

Jan 1, 1959

By James S. Foster, Paul G. Shewmon, Frank V. Nolfi

Analytical expressions are developed for the kinetics of dissolution or growth of a spheroidized, solute rich stoichiometric Precipitate in the surrounding matrix. There are two limiting cases; in one the rate of dissolution or growth is limited by long range solute diffusion through the matrix and in the other by the transfer of atoms across the mrdrix-precipitate interface. In the former case local interfacial equilibrium exists while in the latter it does not and the rate of dissolution or growth is controlled by an interfacial reaction. The analysis treats both limiting cases as well as mixed control in a single development, where it is found that the thermodynamic state of the interface is completely specified by a single parameter, o, defined by where K is the reaction rate constant, D is the matrix solute diffusivity, and R, is the precipitate radiz~s. If K is infinite then a is zero and local equilibrium prevails; if K deviates infinitesimally from zero, then a is very near unity and an interfacial reaction is rate controlling. Mixed control occurs for intermediate values of o. From the analytical results, numbers are computed which are useful in determining the duration of interfacial reaction or mixed control; following this time period, long range diffusion is rate controlling. THE rate controlling process or processes governing phase boundary migration has been the subject of much speculation and investigation. Traditionally, the most widely assumed boundary condition in quantitative treatments of this problem has been that of local interfacial equilibrium. This condition implies that long range diffusion of one or more elements controls the migration and is referred to as "diffusion controlled migration" (herein DCM). In contrast to the above view is the proposition that local interfacial equilibrium does not exist and that transport of atoms across the interface is rate controlling. Consequently, this mechanism is referred to as "interface controlled migration" (herein ICM). In processes of the latter type, the activity, a, of one or more elements is discontinuous at the phase bound- ary and the flux, J, across the boundary of a given element is some function of its activity discontinuity, a. One of the most comprehensive contributions to a mathematical description of phase boundary migration is due to am.' His analyses are applicable to precipitation in binary systems in which a) the precipitates are spherical* solute rich compounds of constant

Jan 1, 1970

By Ernest Klepetko

A NOTABLE amount of fossil resin exists in many of the bituminous coal beds of Utah. The upper part of these show a marked concentration of resin, which occurs primarily in the fracture seams. In general, these seams are less than 1/8 in. thick, but it is not uncommon to find coal with areas as thick as 3/8inches. The resin is of the hard kauri variety, with coloration varying from deep blood red to lemon yellow and almost colorless. There is also an almost black variety, which is not readily soluble in the same solvents as the lighter colored resins. These resins are valuable for many industrial purposes. When refined, they are suitable for uses similar to those for which lac resins are usually employed. They are particularly desirable for preparing dielectric varnishes. They are also desirable in preparing printing inks, waterproofing agents, special synthetic rubbers and rubber cements. They are especially suitable as an admixture in synthetic rubbers and cements, as they supply the essential tackiness the synthetics lack. The following chemical trade characteristics have been found by Inter-Chemical Co. research chemists in the refined resins: [Specific gravity (melted) 1.03 -1. o6 Acid number6-8 Softening point, mercury method 160 -165°C Iodine value (Wijs)140-1.50 Refractive index1.544 Color (Hellige, 25 pct toluol) ...14 Molecular weight, average732 Purity, 99 + pct pure hydrocar Bon] "Unaffected by alkalies and resistant to one hour fusion with solid potassium hydroxide. Completely soluble in aliphatic and aromatic hydrocarbons. Insoluble in alcohols, ethyl acetate and other commonly used alcohols and esters. Compatible with natural and synthetic rubbers, chlorinated and cyclized rubbers, waxes, vegetable oils, mineral oils, rosin, ester gum, phenolic and modified phenolic resins and other natural and synthetic resins of like solvent solubility. The recovery and refining of these fossil resins has been the subject of much research work and has intrigued many investigators. Broadly speaking, the problem involves separation of the resin from the coal into a very high-grade concentrate, and subsequent treatment of this concentrate to produce an acceptable refined resin for its various usages. Obviously it is also desirable to recover the residual coal without excessive size degradation. The late W. D. Green, concentration engineer for Combined Metals Reduction Co., obtained U. S. Patent No. 1773997 for the recovery of resin from coal through

Jan 1, 1947

Cortez Gold Mines operated a conventional 2,100 mtpd (2, 300 stpd) cyanidation plant until the 5 million ton ore body was worked out in 1973. (See Gold and Silver Cyanidation Plant Practice by F. W. McQuiston, Jr. and R. S. Shoemaker, Society of Mining Engineers, AIME 1975.) Sub-grade material was dump leached at the mine -mill location in 1971, and the resulting pregnant solutions were added to the feed in the plant's Merrill-Crowe precipitation unit for gold recovery. In early 1973, however, Cortez put into operation their Gold Acres mine which was located about 13 krn (8 miles) to the west of the 'Cortez mine. Economics at that time dictated the heap leaching of the lower grade portion of the ore body with the higher grade being trucked to the Cortez plant for milling. Leach ore was moved directly from the open pits to prepared leach pads located on a gently sloping terrain of 570 grade. Preliminary pad preparation at the leach site included removal of vegetation which was composed of sagebrush and grading of the base. Pads were comprised of mostly minus 74 micron (200 mesh) materials and were made of clay-silt or slime tailings spread on the pad area in thin 50 to 75 mm (2 to 3 in. ) layers, compacted with a vibrating roller compactor to a depth of about 380 mm (15 in.). This was followed with a 100 mrn (4 in.) layer of coarse rock to prevent erosion on the pad and to allow solutions to move laterally under the heaps. Leach solutions normally traveled the length of the heaps and were collected in plastic-lined ditches from which they flowed by gravity to the pregnant solution storage pond. Both pregnant and barren ponds were constructed in the same manner as the leach pads - being lined with compacted tailings or clay silts. The Gold Acres facility required pregnant solution storage of 6 million liters (1.6 million gal) and barren storage of 3.8 million liters (1.0 million gal) designed to handle two to three days of heap drainage or to retain run-off from a major rainfall. Various heap heights were tried including 3, 6, and 9 meters (10, 20, and 30 ft), with a 6 m (20 ft) height selected. Ore was dumped by trucks in a single 6 m (20 ft) lift using a D8 Caterpillar dozer for

Jan 1, 1981

By John M. Hartman

The high temperature of the blast of modern furnaces renders it desirable that the pipe conveying the blast into the furnace crucible shall transmit and radiate as little heat as possible. To accomplish this, the pipe shown in the accompanying sketch was devised and patented. It consists of a slide-valve, leg-pipe, and belly-pipe, which are held together and to the tuyere by a system of levers and links. The slide-valve is superior to the old throttle-valve. The legpipe is formed of two thicknesses of wrought-iron pipe, with a space of half an inch filled in with clay and brick. The belly-pipe is made in the same way as the leg-pipe, and terminates in a globe face to suit the tuyere. The quarter turn is made extra thick, of cast iron, and the cap on the end is lined with clay also. The catches, A, B, C, are merely for convenience in putting the pipe together. The joints D and E are globe faces, and allow the pipe to adjust itself to any angle. The eye-piece is made of violet glass, which cuts off the glare from the bright coals in the furnace and allows a close examination of the interior, so that any water dropping or vapor can be detected. The glass does not become coated with dirt, like mica. Since good running of furnaces is shown by a bright tuyere, it is necessary to have a good eye-piece to examine them. To detach the pipe, a man lifts the weights, the side rods are then slipped off the bell crank under the quarter turn, the link under the belly-pipe is unhooked, and the pipe carried away. The same process is reversed to put the pipe together. The nozzle is changed by taking off the cap, G, drawing the nozzle through the belly-pipe, and inserting another. In this way the change can be made quickly, without taking down the pipe. On the old tuyere pipe bolts with brass nuts were used, which burned up and gave trouble. In other cases key-bolts were used, making it difficult to adjust the pipe. Bolts make too rigid a joint, and there is no provision for movement from contraction or expansion. As the temperature of the blast increases there is more expansion, and where rigid joints are

Jan 1, 1879

By John M. Hartman

THE high temperature of the blast of modern furnaces renders it desirable that the pipe conveying the blast into the furnace crucible shall transmit and radiate as little heat as possible. To accomplish this, the pipe shown in the accompanying sketch was devised and patented. It consists of a slide-valve, leg-pipe, and belly-pipe, which are held together and to the tuyere by a system of levers and links. The slide-valve is superior to the old throttle-valve. The leg-pipe is formed of two thicknesses of wrought-iron pipe, with a space of half an inch filled in with clay and brick. The belly-pipe is made in the same way as the leg-pipe, and terminates in a globe face to suit the tuyere. The quarter turn is made extra thick, of cast iron, and the cap on the end is lined with clay also. The catches, A, B, C, are merely for convenience in putting the pipe together. The joints D and E are globe faces, and allow the pipe to adjust itself to any angle. The eye-piece is made of violet glass, which cuts off the glare from the bright coals in the furnace and allows a close examination of the interior, so that any water dropping or vapor can be detected. The glass does not become coated with dirt, like mica. Since good running of furnaces is shown by a bright tuyere, it is necessary to have a good eve-piece to examine then. To detach the pipe, a man lifts the weights, the side rods are then slipped off the bell crank under the quarter turn, the link under the belly-pipe is unhooked, and the pipe carried away. The same process is reversed to put the pipe together. The nozzle is changed by taking off the cap, G, drawing the nozzle through the belly-pipe, and inserting another. In this way the change can be made quickly, without taking down the pipe. On the old tuyere pipe bolts with brass nuts were used, which burned up and gave trouble. In other cases key-bolts were used, making it difficult to adjust the pipe. Bolts make too rigid a joint, and there is no provision for movement from contraction or expansion. As the temperature of the blast increases there is more expansion, and where rigid joints are

Jan 1, 1879

By Carville E. Sparks, Rollin Farmin

Edward Thomas (U.S. Bureau of Mines, Washington, D. C.)—This excellent article on an ingenious and successful installation of wooden rock bolts loses much of its effectiveness through an attempt by the authors to establish the general adaptability of this type of support. Possibly because they have only local experience as a guide, they imply erroneously in the first paragraph that the Bureau of Mines has been opposed to wooden bolting, although later in the article reference is made to a Bureau publication on the subject. In 1947 the Bureau of Mines decided to sponsor experiments in roof bolting in coal mines because the experience of the St. Joseph Lead Co. had indicated that this type of roof support appeared to be a roof-fall accident-prevention measure that might be adopted and also effect economies in operating cost. Justification for this belief has been borne out, particularly in coal mining. This program has been carried out under the following general program: 1—The Roof Control Section of the Bureau of Mines has advocated and initiated underground experiments under controlled conditions with many different ideas related to rock bolting since 1947. In no instance has cooperation in developing an idea been refused, no matter how ridiculous it may have seemed at first glance, if it has been requested by a mining company. 2—The Bureau of Mines has no police powers over the selection of roof-support devices and seeks none. 3—At the request of an operator, the Bureau of Mines will make comparative tests on various types of bolts underground and will submit resultant data for the operator's consideration. 4—Wherever possible, the Bureau publicizes successful installations, so that others may benefit from this experience; however, it is careful not to discriminate between manufacturers of bolts or bolt-installation equipment. Unsuccessful experiments probably should also be publicized, but from a practical standpoint it is usually not feasible. In other words, the role of the Roof Control Section of the Bureau is in line with the original purpose for which the Bureau was first organized: to serve industry through gathering, analyzing, and disseminating factual data. It would seem to be logical that the starting point for any experimentation on roof bolts in coal mines should be the time-proved practice of the

Jan 1, 1955

Discussion of the paper of HOWLAND BANCROFT, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 91, July, 1914, pp. 1767 to 1769. THEODORE SIMONS, Butte, Mont. (communication to the Secretary*). -While preparing maps and models for use in mining litigations the writer was frequently confronted with the problem referred to in Mr. Bancroft's paper. His chart gives the apparent angle of dip with which a vein should be plotted on a vertical section not at right angles to the strike of the vein. For a quick determination of this apparent angle the writer has used an exceedingly simple graphical method, which he believes may prove helpful to engineers engaged in practical work. It is submitted, not as a criticism of Mr. Bancroft's paper, but as a means of solving the same problem when no chart is available and when calculations would consume too much time. The writer's method requires merely a few lines marked off on a piece of tracing cloth, as shown in Fig. 1: Draw line be on any convenient scale. At b erect a perpendicular, ba. By means of a protractor cut off on ba a number of angles within the probable range of variation of dip, so that a line connecting a and c, for instance, forms an angle of 60° with be, etc. With b as a center and be as a radius, draw a circle through c. This completes the tool for solving the problem. Fig. 2 represents the line of strike of the vein and db the trace of the vertical plane on which the vein is to be plotted with the apparent angle of dip. A° is the angle which this plane makes with the strike. Fig. 3 shows the application of the method: Place line cb of tracing over line db of Fig. 2 and move fore and back until line of strike becomes tangent to the circle. Connect d with the point (a) that marks the true angle of dip as found by measurement in the mine (60° in the case illustrated). The angle adb is the apparent angle of dip (C°) to be used in the vertical section. Proof.-As stated in Mr. Bancroft's paper, the apparent angle of dip is: tan C° = sin A° tan B° (1)

Jan 12, 1914

PHILIP D. WILSON,* Warren, Ariz. (written discussiont).-Mr. Tovote's idea of attempting to classify according to their broad geologic relations the ore deposits and prospects of the Southwest is an admirable one. Attempts have been made to evolve some comprehensive scheme of classification that would be of practical assistance in determining the possible value of prospects, but the ore deposits are too varied in type, form, genesis, and distribution to lend themselves readily to any definite, scientific pigeon-holing. The classification Mr. Tovote recommends, combining the age of the mineralization with the type of the rock supposed to be its source, is open to criticism even on the evidence he presents. The age of many deposits is not nor can be definitely determined because of the absence of sedimentary rocks in their vicinity. Furthermore, the character of the mineralizing solutions has, in a large majority of cases, no relation to the composition of the associated igneous rock. While the solutions may have originated in the same magma, they were usually a much later manifestation of it, often appearing after the intrusive rock had completely solidified and been subsequently crushed and fractured, and in many cases the chemical difference is very marked. It is true that igneous activity in the Southwest is definitely related to-certain geologic periods. The statement, however, that no ore deposits can unmistakably be referred to periods earlier than late Cretaceous is not supported by fact. The bonanza copper orebodies of the Jerome District are definitely pre-Cambrian. As suggested by J. R. Finlay,1 they are probably post-Beltian or late Algonkian in age, perhaps related to the same great mountain-making period as the copper deposits in the Keweenawan series of Lake Superior and the Sudbury, Porcupine, and Cobalt deposits of Ontario. The proof that they are pre-Paleozoic may be summarized as follows: 1. The pre-Cambrian complex in which they occur is overlaid by a great thickness of Paleozoic sediments with the Tonto or Tapeats sandstone at their base. The only primary mineralization in these sediments is an economically unimportant one connected with very recent basalt. 2. In the United Verde Extension mine, the gossan over the great orebody extends to the old pre-Cambrian surface where it is directly

Jan 2, 1919

G. SHERBURNE ROGERS,* Washington, D. C. (written discussion?).- We are indebted to Captain Lucas for an interesting contribution to the literature of the salt-dome oil fields, and especially for his suggestion that a more aggressive method -of prospecting be adopted. The occasional discovery of new fields on, the Gulf Coast is in itself sufficient to show that the oil possibilities of the region are by no means exhausted, and those who have studied the area most thoroughly are the most optimistic regarding its future. Nevertheless, the search for new fields, according to present methods, involves the expenditure of great sums of money annually, for the proportion of dry holes to producing wells drilled yearly in the Gulf Coast region is much' greater than in most areas, even if all the wells drilled in what is commonly regarded as proved territory are included. Not only are the present methods of locating new domes very uncertain, but when a dome is discovered there is no assurance that it will be oil-bearing; or, if so, whether the oil occurs in the cap-rock, in the sands above it, or in some small isolated lens of sand far down on the flanks of the salt mass. As Captain Lucas points out, about all we positively know is that the domes are there and that some of them are oil-bearing; their origin is a matter of controversy and the original source of the oil is conjectural. Under these conditions, it is not surprising that the search for oil is conducted more or less blindly and that dry holes are common. Many wells are drilled each year in an endeavor to find oil at depths of 2000 or 3000 ft. (609 to 914 m.) or less, in locations which most geologists would condemn without hesitation. As Captain Lucas suggests, the money spent in this way might be used to far better advantage in, drilling one deep well in a carefully selected locality. Opinions may differ as to whether such a, well would find oil, and many geologists will probably believe that the chances are against it, yet all will agree that the boring, whether it finds oil or not, will probably throw light on the origin of the domes and on the source and mode of accumulation of the oil, and will therefore be of great interest, not only to the scientist, but to the oil operator.

Jan 10, 1918

AT the Wednesday morning session on Mine Ven-tilation, D. Harrington's report of the committee on metal mine ventilation was presented. He said the only paper which had been received was one from Nevada, although a number had been promised. Mr. Harrington gave instances from his experience where it had cost less to operate ventilating fans during idle periods in mines than the expense of replacing timber, which was destroyed by fungus during the period when the mines were not ventilated. He referred particu-larly to a metal mine in Michigan and a copper mine in the Southwest where this condition had been found in parallel tunnels, one of which had been ventilated after work had ceased and the other had not been. Mr. Harrington also referred to the fumes after blasting operations in mines operating in large bodies of sul-fide ores. By installing mechanical ventilating devices, these conditions had been greatly improved. He re-ferred also to a recent instance where an ignition of sulfide ore-dust had resulted in an explosion which killed three men and burned a fourth severely. Methane had been found in some gold mines and also in tunnels for city water-supply, and as a result coal-mine inspec-tion methods had been adopted. In one instance the contractor had changed from 40 per cent gelatine ex-plosive to a permissible explosive. A daily gas sample was taken. Nitrogen had been found in some of the mines, and CO, gas had been found in some of the Cripple Creek mines where a fan had been installed to maintain pres-sure on the working faces. It was found by experiment that the oxygen was absorbed by the rock particles, which led to a relatively greater percentage of CO. Coal-mine splitting ventilating methods had been used in some places. Miners' consumption had been made compensable in Ontario, and there is a large threat-ened charge now standing against metal mine oper-ators in the Province of Ontario. Mr. Harrington re-ferred to some of the literature, especially the recent book on ventilation by W. S. Weeks of the University of California. He suggested, however, that a better title for the book would have been "The Physics and Mechanics of Metal Mine Ventilation," since it was especially valuable in this field.

Jan 3, 1927

By E. E. Barker

ALTHOUGH flotation was known to be a successful process prior to 1912, Utah Copper Co.'s ores were not entirely treated by this process until 1923. Experiments had been conducted, of course, prior to that time, and in February, 1917, the first unit of the Arthur plant was changed over from gravity concentration to flotation. On May 16, 1918, the entire Arthur plant was on flotation, excepting the coarse concentrate which was tabled prior to fine grinding. The reasons for the delay in adopting flotation at these plants were, first, that it was decided to await the outcome of the litigation with the Butte & Superior Mining Co., which began with an injunction served on Oct. 3, 1911. This litigation continued for years. Then the demands on the plants in the war years 1916, 1917 and 1918, really precluded any further drastic changes during that period, as all efforts were bent on maximum tonnage, and the cry of tonnage, rather than of recovery, was the major issue. The postwar depression followed these years of intensive production, so that it was not until 1922 that the Magna plant was equipped to use this process. Excepting, then, the amount of coarse concentrate that was tabled, 1923 was the first year when the Utah Copper Co.'s ores were on, a full flotation basis. EFFECT OF FLOTATION ON ORE RESERVES The object of this paper is to point out the effect that flotation has had on the operations of the Utah Copper Co. In 1905, when D. C. Sackling began making history in copper, the ore reserves were 34,000,000 tons, with a grade of 2 per cent. copper and a mill capacity of 700 tons daily. The point of cut-off between nonprofitable and profitable grades was 1.2 per cent. A few years later the capacity was increased to 6000 tons, when 1.1 per cent became the point of cut-off. Ore reserves had climbed to 80,000,000 tons, having a grade of 1.9 per cent. In 1911 there was an ore reserve of 300,000,000 tons, with a grade of 1.5 per cent and a cut-off of 1 per cent.; in 1918 the ore reserve was approximately 400,000,000 tons, and a grade of 1.38 per cent., and point of cut-off 0.95 per cent., based on normal costs and prices. Up to this

Jan 1, 1928