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By E. L. Corp, J. C. Johnson, W. G. Pariseau, M. Poad, M. E. Fowler

This paper describes a comprehensive geomechanics case study of a full¬scale test stope at the Carr Fork Mine. The mine is owned by Anaconda Miner¬als Company and is located near Tooele, Utah. Large diameter blast holes were used in a new method known as blast hole post-fill (BHPF). The new design proved highly successful in contrast with earlier experience with vertical crater retreat (VCR) stopes. The main geomechanics objective was the estab¬lishment of a design procedure for optimizing stope and pillar dimensions with respect to productivity and recovery. An integrated three-part approach consisting of mine measurements, laboratory testing and finite element calcu¬lations was taken. Independent correlations of 0.88 and 0.89 between calculated and measured displacements and between estimated and observed yield :ones substantiate the finite element design approach using UTAH-II. Subse¬quent stope and pillar design analyses indicate that doubling of the original stope width at 50% extraction is quite possible without sacrifice of safety or stability.

Jan 1, 1984

By G. W. Brownell, H. T. F. Lundberg, R. W. Pringle, K. I. Roulston

The rapid improvement of the airborne scintillometer and the perfection of its efficiency for counting low energy gamma radiation has made it possible to work out a technique to map in great detail the radiation pattern at the earth's surface. On such maps low radiation over certain areas appears to indicate the existence of oil accumulations, forming a pattern similar to that obtained by the geo-chemists. RADIOACTIVE analyses of samples from the surface of oil fields were carried out more than 10 years ago in Alberta by the alpha particle ioniza-tion chamber technique,' but large enough tracts could not be covered in these investigations to make possible any evaluation of the method as a means of oil exploration. Considerable interest has recently been revived, however, as a result of certain striking advances which have been made in the instrumentation available -for the measurement of radioactivity. It is the object of this paper to indicate the nature of these improvements in radiation technology and then to describe the attempts that have been made to interpret the radioactive patterns obtained in the course of airborne recordings with the new instruments. Since the survey can be carried out from the air and records can be accumulated over vast areas in a short time, the result may easily lend itself to statistical treatment. Areas have been surveyed in Alberta, British Columbia, Saskatchewan, Quebec, Texas, New Mexico, Nebraska, Colorado, Utah, and Montana. Producing fields in Alberta and West Texas have been flown over several times in different directions, Fig. 1. The operations were then extended into unknown territory and drill holes were put down on the anomalies which looked promising. The results from these drillings were encouraging and have given hopes for the development of an entirely new method of oil exploration. Any large scale method for the survey of radioactive anomalies must be based on the measurement of gamma rays, as beta and alpha rays have much too short a range to be of any significance. Thus the essential improvement which has made the present stage of this work attainable is the development of new highly sensitive detectors for gamma radiation. In the past the only detectors of any consequence that were available were the ionization chamber and the geiger counter, but both of these suffer from the defect that only a small proportion of the gamma rays passing through the counter are detected, possibly 0.1 to 0.2 pct. The recent development of the scintillation counter2,3 has completely transformed the situation and has had a considerable impact on many branches of nuclear technology. The detection of alpha particles in zinc sulphide screens by visual observation of the individual scintillations which these particles produce dates back to the early spinthariscope of Rutherford and Crookes, but the combined use of an appropriate scintillating phosphor and photomultiplier tube had to await the technical development of the latter many years later. With this development came the modern era of the scintillation counter and a knowledge of phosphors which have a large light output under the bombarding action of gamma radiation. Some of these phosphors are relatively dense and are capable of stopping a large proportion of the incident gamma radiation. As the sensitive region is the whole volume of the crystal, a very high detection efficiency, 50 pct or more, can be obtained for medium energy gamma rays. Scintillation counters for geological purposes were first developed in 19494-6 in an attempt to utilize this remarkable improvement in efficiency, which has the attractive consequence that only a small portion of the normal background of the counter is due to cosmic radiation. In 1949 tests were made in northern Saskatchewan by Lundberg Explorations Ltd. with portable scintillation counters which gave excellent results in the search for uranium and served to indicate unknown uranium deposits in areas previously closely surveyed with geiger counters. Portable scintillometers (registered in Canada) are now commercially available and in regular use,' and the adaptation of the instrument to radioactivity oil well logging has also been very successful.8 Initial attempts to measure radioactivity from aircraft with scintillation counters were made during this period in the same area and yielded most encouraging results. It would be appropriate to consider some specific requirements for airborne investigations. The essential problem to be met in the detection of any radioactive source is the necessity of obtaining a signal greater than the statistical fluctuations of the background counting rate for the instrument. It is possible to show that Nt>2k2 is the condition for detectability of a signal where N = average background counting rate for the detection. t = time constant of the counting rate meter, used to determine the average number of counts arriving in a certain predetermined time interval. N' = average source counting rate at the detector. k = N/N', and N>>N'. Sample values are given in Table I. Assume that the aircraft carrying the equipment is travelling at 120 mph, in which case it will cover 176 ft in 1 sec. Assume also, as a first approximation, that a point source target is in range when the air-

Jan 1, 1954

By Ralph Arnold

The lure of possible new oil fields shut off development of the older Montana fields during the year 1928, cutting down the total production to less than the 1927 mark. However, with the production of oil worth approximately $7,000,000 during the past 12 months, Montana oil producers pushed their total up to $44,000,000 taken from two principal fields during the past 8 years. The highest prices in the United States for oil of similar gravity gave northern Montana producers a decided advantage and brought up the value of the oil to about the same value as the 1927 production, although the oil runs were 1,000,000 bbl. less. Production by Fields The discovery of two new oil fields in the Sweetgrass Arch, in north central Montana, in 1927, diverted attention from the Kevin-Sunburst field. Many operators turned their attention to wildcats and practically all of the drilling contractors were called into the new Pondera and Bannatyne fields. Although discovered in 1927, the Pondera field developed its first commercial production in March of 1928. Mild interest was followed four months later by a rush of operators, and by August practically every string of tools had been moved from the Kevin-Sunburst field to Pondera. The fall months found 40 wells drilling in this field and as the year closed there were 100 producers. Pondera field is remarkable in that every well thus far drilled within the structure proper has been a producer. Dry holes have been drilled around the field, but none within an area of four sections. Experts estimate that Pondera will produce 5000 bbl, of oil to the acre. The producing area now outlined by wells drilled is expected to produce around 15,000,000 bbl. of oil. Pondera crude brings $1.75. This field has one pipe line and a second line is being laid. Lack of a pipe line delayed development of the new Bannatyne field, south of Pondera, and also in the Sweetgrass Arch. Bannatyne has 11 producing wells scattered over an area of approximately three sections. Bannatyne is a sand field with a 70-ft. sand in the lower Jurassic, which core-drill tests show to be 60 per cent. saturated. With the completion

Jan 1, 1929

By H. De Cizancourt

AS in former years, Pechelbronn, in Alsace, was the most important producer in 1936, with 484,453 bbl., of which 283,151 from drilling and 201,302 from mining showed a slight increase in comparison with the preceding year. Gabian, in France and Tliouanet, in Algeria, are nearly exhausted. At Gabian, four wells drilled in intermittent exploitation produced during the year 2893 bbl. Four wildcats, one of which is producing, constituted all the activity in research on French territory. In Morocco, some wildcats have been drilled in search for new fields and exploratory drilling has been done in Tselfat and in Djebel Bou Draa in known fields, but the results have been inconsiderable. In Tunisia there was a gas outburst in Kebir 1, which is the first practical result obtained. In Madagascar, the Andrafiavelo region has been left and a new region has been tried in Folakara with the Tsimororo. In French Equatorial Africa, one drilling is in progress.

Jan 1, 1937

By W. J. Travers

SEVERAL new procedures for completing oil wells have been developed in recent years. Each method when used where properly applicable promises to be a definite aid to operators in lowering development or operating costs, or in developing the full potentialities of the oil well. Multiple-zone completions are now frequently used, in contrast to the older practice of setting a solid water string over each zone to be produced. Gravel packing in unconsolidated formations often prevents sand troubles formerly experienced where a conventional perforated liner was used. Light-weight bentonitic clay muds and oil-base drilling fluids are definite steps toward eliminating mudding damage, which occurs when heavy rotary mud is used. Since in each case the new procedure developed is an alternate of older conventional methods, a problem of selection is presented. The purpose of this paper is to suggest methods of arriving at these choices and to present practical observations that may be of aid in their application.

Jan 1, 1942

The following are excerpts from the report of the Treasurer of the United Engineering Society, for the year ending Dec. 31, 1915. Finances Due to the growth of the activities of the United Engineering Society, it was found desirable early in the year to consolidate the various accounts and financial records of the Society and of the Library, heretofore kept separately, and to have all the data pertaining to the building and its operation in the charge of one individual. An assistant secretary especially assigned to this work has been appointed, and a separate office has been established. The Finance Committee has had all of the records brought fully to date and has prepared a new set of account books to meet the new conditions. The Real Estate Account now includes the following items: Land $ 540,000.00 Building 1,050,000.00 Equipment 33,171.16 Founder Societies, Preliminary expenses 24,000.00 Total $1,647,171.16

Jan 4, 1916

By L. Michael Kaas

The mineral industries are striving to expand their use of the computer's ability to process exploration, geologic, and mining data. Digital plotting programs and devices are continuing to gain wider use for lowering the cost and the time required to produce many types of maps and cross-sections commonly used by mining companies. Mineral engineers and geologists will soon be using a new tool, computer graphics, to greatly facilitate the use of computers to solve a large number of industry problems. By means of cathode-ray-tube (CRT) displays, an engineer can search large files of geologic data; display elevation contours, geologic structures, and ore grades; construct geologic and mining cross-sections; and compute tonnages for mining plans or ore reserve estimates. Examples of both digital plotting and cathode-ray-tube problem solving approaches are discussed in this paper.

Jan 1, 1969

By Hugh D. Pallister, Richard W. Smith

The Alabama flake-graphite industry has flourished only in times of war when importations of foreign graphite for crucible use have been greatly curtailed or cut off. World War I was a boom period and in 1918 some 30 plants produced 7,795,475 lb. of flake graphite. The industry languished following the war and no graphite was produced from 1929 to 1939. The Federal Bureau of Mines began investigating the Alabama graphite deposits in 1940 and worked out modern recovery methods that were applied to production during part of World War II. A prospecting program disclosed reserves of over 25 million tons of graphitic schists. In 1942 the War Production Board authorized the enlargement of the only plant then producing flake graphite and the construction of two new plants. Production of flake graphite from these three plants in 1943 is estimated at 8,100,000 lb. Increased imports from Madagascar late in 1943 shut down one of the new plants and curtailed production at the other. Alabama flake graphite has not yet been able to compete with Madagascar graphite for use in the manufacture of any but small graphite crucibles. The future of the industry must depend on meeting the higher carbon content demanded for other uses.

Jan 1, 1945

By James F. McConnell, Charles W. Statler

Pennsylvania's existing large coal-fired units are limited to 2.0, 1.8, or 0.6 lb of sulfur per million Btu fired, depending on site location. Multi-stream coal preparation can be employed on system basis to extract the highest quality fraction of coal for use in units requiring the lowest sulfur. The middling fraction can be directed to units permitted higher sulfur. General Public Utilities Corp. has concluded that it is feasible to advance the state-of-the-art of heavy media coal preparation to produce an intensively cleaned primary product of 1.3 sp gr of less than 0.6 lb of sulfur per million Btu for the new unit and a middling product of 2.0 lb of sulfur per million Btu for existing units.

Jan 1, 1977

By Samuel G. Lasky

What the evidence prevails upon the mind to believe, depends upon the mind as well as upon the evidence. M. L. IN a recent discussion of the mineral resource position of the United States, published in the September 1946 issue of MINING AND METALLURGY, I expressed my conviction that ore deposits of major magnitude remain to be found in this country and that they can be found without undue cost or risk. I stated with equally strong conviction, however, that if the search for such deposits is to be notably successful there must be, among other things, a reorientation of philosophy and mental habits on the part of many who would be connected with the search. I would now like to enlarge upon that statement. For such a purpose, we may consider that the search for concealed deposits involves four steps: (I) the selection of areas for further study; (2) the geologic study of those areas in order to verify their general favorableness and in order to choose specific patches worthy of being tested; (3) the decision whether exploration of the patches chosen should actually be undertaken; and (4) the exploration itself. The first two steps and the last rest upon the judgment and skill of geologists. The third step-the decision whether exploration should be undertaken-rests upon management. In my opinion, the philosophies or principles that have guided these steps in the past are now inadequate. PHILOSOPHY OF APPRAISAL If concealed deposits are to be looked for, how are the places of their possible concealment to be recognized? Every known mineralized area still in the prospect stage has already been repeatedly examined and condemned. As for those deposits concealed under later rocks, there may be not even the clue of a near-by outcrop for engineer or geologist to consider. How then, are we to know where to look? Geologic Probability In the early days of our mining industry, ore deposits were found mainly by "following the ore." Later, as such opportunities decreased, and as geologic concepts became accepted, deposits were found more and more through use of the notion of geologic probability. Many instances can be cited wherein a courageous operator ignored the implications of the unsuccessful efforts of predecessors and, solely by "following the ore," converted a discredited prospect into a good mine. Similar experience doubtless will occur in the future, but "following the ore" will no longer in itself find new deposits in the amount needed. Nor can enough new ore be expected from further use of the notion of geologic probability, for, as mentioned above, our known prospects `have already been ex-

Jan 1, 1947

By T. L. Joseph

IN connection with its investigations of the blast'-furnace process, the Bureau of Mines, in coöperation with the Minnesota School of Mines Experiment Station, developed a 6-ton experimental furnace. Such a furnace was needed to determine the feasibility of producing ferromanganese from Minnesota manganiferous iron ores, a problem of national importance because of the present need for manganese in the steel industry and our small reserves of ferro-grade ores. Furnace operators are reluctant to use new or untried raw materials or to make decided innovations in practice on account of the financial hazard of experimenting with full-scale equipment. A small furnace which can be operated at a relatively low cost is particularly adapted for testing new, raw materials and for determining the feasibility of decided innovations in practice. Laboratory experiments, plus whatever information may be available, are valuable but often do not indicate the net result of changes in an operation involving a large number of interrelated variables. From time to time the coöperation of the Bureau of Mines is solicited in connection with problems involving departures from normal procedure. Under these circumstances some sort of a practical demonstration is a desirable forerunner to full-scale operations which appear feasible after small-scale tests.

Jan 1, 1928

By K. J. Brondyke, P. D. Hess

Two processes have been developed for improving the quality of molten-aluminum alloys before casting. The Filtration Process. which involves passing molten metal through a packed bed of granular filter material, is a rapid means of removing finely divided particles. It has the most potential in those instances where removal of inclusions is of primary importance. The Combination Fillration-Inert Gas Fluxing Process inuolzles introduction of an inert gas so that it will diffuse countercurrent to metal flow through the filter bed of granular material. Dissolved hydrogen is removed from the metal in addition to removal of finely divided particles. The Combination Process is most useful where both inclusion removal and attainment of conistently low-hydrogen-content metal are important. Metal treated by the Combination Process is of higher and more uniform quality than heretofore attainable with prolonged chlorine fluxing. Costs of the Combination Process can, for the most part, be offset by savings derived from high recoveries and increased production of superior-quality products. IMPROVEMENT in the quality of molten-aluminum alloys is secured generally through the use of some fluxing practice in a crucible, holding furnace, or ladle involving either gaseous or solid fluxing media. Typical fluxing agents may include the gases nitrogen, argon, or chlorine used either singly or as mixtures and the solids aluminum chloride or hexachloroethane. Regardless of the fluxing means used, the primary objectives are the adequate removal of both metallic and nonmetallic inclusions and reduction of hydrogen content to an acceptably low level. The ultimate goal is to produce ingots and cast products of high quality free from inclusions and porosity. The development of ultrasonics for measurement of internal quality, tightening of quality controls, and the application of the aluminum alloys to new or different commercial fields have been responsible for an ever increasing demand for improvement of quality of both cast and fabricated products. This demand for high quality has not been restricted to any single type of product. On the contrary, the demand encompasses about the entire variety of products including those for fabrication, those to be machined, buffed, or finished for decorative purposes, and those for critical applications where both surface and internal quality is of utmost importance. In many instances products acceptable in the 40's would now be scrapped as unacceptable by these higher present-day standards. With this ever increasing demand for higher quality, it became apparent at Alcoa that conventional means of melt treatment were inadequate in many instances and new approaches were necessary. Consequently the research program was intensified with attention focused on metal treatment during transfer in order to reduce the furnace processing time to a minimum in an effort to attain the desired results at a minimum of additional expense. As a result of this intensive research program which covered numerous variations and adaptations of conventional methods in addition to new methods of melt treatment, several new processes were developed, two of which will be described here. The first of these, a method of melt filtration, was patented in February, 1959.l The second process involving combination filtration—inert gas fluxing was patented in June, 1962. 2 Other melt-treatment processes developed during this period of investigation were patented as listed.3 FILTRATION PROCESS General Description. The Filtration Process, which involves passing molten metal through a packed bed of granular filter material, is a rapid method of effectively removing finely divided particles. It is an impingement-type filter; hence the size of the particles removed from the metal are considerably smaller than the interstices of the

Jan 1, 1964

By Helmut Thielsch

METALLOGRAPHIC specimens whose surfaces are to be investigated are too thick to allow either light or electrons to pass through them for microexamination by transmission. This difficulty is overcome with optical microscopes by illuminating the surface through the objective lens. For electron microscopes best results are obtained by preparing thin replicas of the surface of the specimen, placing them in the microscope and passing the electron beam through them. Since electron microscopes represent a rather recent invention, they have found little application as compared with optical microscopes. This is true because, aside from the cost of new equipment and development of new techniques, some of the older replica methods necessitated the destruction of the surface from which a thin transparent replica was obtained. In other processes in which the surface is preserved, either too tedious a procedure is required, unsuited to "mass-production " requirements of industrial laboratories, or replicas of insufficient contrast and sharpness are produced. In general, investigations with the electron microscope involve five steps: (I) polishing the surface of the metal specimen, (2) proper etching of the surface, (3) preparing the suitable replica from the surface, (4) examination and photography in electron microscope and (5) interpretation. PREPARATION OF METAL SURFACES Usual metallographic polishing is generally satisfactory. It is important though that the final polish be applied very care- fully, since otherwise evidence of a small amount of deformation might show up even on relatively deeply etched surfaces. A high-power microscope should be used to determine the suitability of the polish and etch. This, of course, is not different from optical examinations, but in these, if a deep etch is used, the problem is less serious. It is frequently difficult to detect with optical microscopes poor polishing aside from superficial scratches before etching. Figs. I and 2 show micrographs of "well" and "poorly" polished nickel etched by immersing the same for 20 min. in a solution containing 8 grams cupricsulphate in 40 C.C. of concentrated HCl and 40 C.C. of H20 (Marble's reagent). The sample shown in Fig. I was polished in its final stages for 5 min. on a carborundum wheel followed by 10 min. on a rouge wheel, whereas the sample shown in Fig. 2 was polished only I min. on the rouge wheel. Generally, this procedure does not guarantee that the surface of the specimen will be either undistorted or deformed. It was applied here merely to show the effects of good and poor polishing. To the experienced investigator, plastic deformation is

Jan 1, 1946

The 116th (New York) Meeting of the Institute will be held in the third week of February, 1918. The Committee on Papers and Publications has set Dec. 1, 1917, as the closing date for the receipt of .manuscripts intended for this meeting. Manuscripts must be received by the Secretary on or before this date. If they are sent through members of the technical committees they must be sent to those committees enough in advance of the time to be forwarded and in the. hands of the Secretary by the time specified.

Jan 11, 1917

By Rossiter W. Raymond

The term " pipe-vein " has recently been applied in this country to certain deposits of lead ore in magnesian limestone. The use of the term has been twofold. It has been revived as a term found in textbooks on mineral veins, with the implied or declared assertion that the ore-deposits thus named in this country are similar to those which have borne the title abroad. It has also been advanced as an appropriate name for a new class of deposits, even if such a class had not previously been recognized. In either case, the assumption is that pipe-veins form a group or class by themselves, and are not merely interior and subordinate features in larger deposits. The peculiar mining law of the United States, which regards " the vein," whatever that may be, as the basis of title, lends a special interest to these claims. But the object of this paper is rather to discuss the subject from the standpoint of geology and technical literature. I shall briefly answer two questions: (1) What are pipe-veins as described in technical literature? and (2) Is the name appropriate or necessary for a new class of deposits ? The term " pipe-ore," as applied, for instance, to irregular, cylin-

Jan 1, 1879

By Rossiter W. Raymond

(Read at the Amenia Meeting, October, 1877.) THE term "pipe-vein" has recently been applied in this country to certain deposits of lead ore in magnesian limestone. The use of the term has been twofold. It has been revived as a term found in textbooks on mineral veins, with the implied or declared assertion that the ore-deposits thus named in this country are similar to those which have borne the title abroad. It has also been advanced as an appropriate name for a new class of deposits, even if such a class had not previously been recognized. In either case, the assumption is that pipe-veins form a group or class by themselves, and are not merely interior and subordinate features in larger deposits. The peculiar mining law of the United States, which regards " the vein," whatever that may be, as the basis of title, lends a special interest to these claims. But the object of this paper is rather to discuss the subject from the standpoint of geology and technical literature. I shall briefly answer two questions : (1) What are pipe-veins as described in technical literature? and (2) Is the name appropriate or necessary for a new class of deposits ? The term "pipe-ore," as applied, for instance, to irregular, cylin-

Jan 1, 1878

By Georges Fleming

The new burden preparation plant of ARBED Luxembourg, Belval- Works, which comprises 2 large sinter strands, is equipped with a process computer connected to a comprehensive process control system. The main jobs done by the computer are the control of the raw mix composition, and thus the monitoring of the stacking of the piles at the bed-blending plant, and the optimization of the sintering process. Among the optimization criteria, quality is considered as the most important. The sinter quality, characterized by the mechanical strength and the state of oxidation, is controlled automatically. The control system which we have dev loped is highly reliable; as a result, the standard deviation of Fe++, for the control of bivalent iron, has been narrowed to 0,5 % and the standard deviation of the IS0 + 6, 3 mm index, for the control of the mechanical strength, has been kept within 1 %. Thanks to these results, the combined savings in fuel consumption at the sinter plant and at the blast furnaces have covered the total costs of the optimization project in 2 years. By applying automatic control, the optimum driving range of the sinter plant has been defined and these new guidelines are used for monitoring the sinter production.

Jan 1, 1977

By AIME AIME

COMPLETION of the Rainbow Bridge across the Niagara River and Gorge this fall marks a new page of achievement in the annals of bridge- building. Symbolic of the amity between two great nations, the new bridge provides an additional gateway across the most peaceful border in the world. Ground was broken for the project May 16. 1940, at a site close to that formally occupied by the Falls View Bridge which was destroyed by a record ice jam in 1938. At this point, about 2000 ft. deep and 1000 ft. downstream from the American Falls, the gorge is about 200 ft. deep and 1000 ft. wide. The great steel arch of the bridge has a span of 950 ft. and rises from its supporting abutments on the American and Canadian sides of the river to the level of the top of the gorge. This is said to be the longest hingeless arch in the world.

Jan 1, 1941

By AIME AIME

ANDREW FLETCHER, newly elected Treasurer and Director, has spent his entire mining career in the employ of the St. Joseph Lead Co. and brings to the Institute Board a career rich in financial experience and varied in interest and accomplishment. "Drew" Fletcher was born in New York City on Feb. 6, 1895. After graduating from the Sheffield Scientific School of Yale in 1916 as a mechanical engineer, he became a shipyard mechanic in Wilmington, Del. The next thirteen years saw. him gradually enlarging his responsibilities until he ultimately became the head of the W. & A. Fletcher Co., in Hoboken, N. J., ship repairers. In 1929 his program for merging the Fletcher plant with five other New York shipyards was finally consummated in the formation of the United Dry Docks, Inc., which subsequently was purchased by Bethlehem Steel, with the result that today the old Fletcher yard and organization has been expanded into one of the finest ship repair units in the United States.

Jan 1, 1944

By Joseph G. Wargo

A meteoric rise in selling price has revived gold exploration activity throughout the world. In the United States the effort is, in large measure, channeled toward discovery of disseminated gold deposits such as the Carlin-type, i.e., with size and grade characteristics similar to Newmont's Carlin mine in Nevada. The subtle surface indications characteristic of Carlin-type gold mineralization have been examined by a number of geologists, and the more obvious prospects have been tested by surface sampling and drilling. It is likely that most of these readily recognizable deposits have already been found and, as a consequence, prospectors are now entering a new, second stage of exploration for Carlin-type and related disseminated gold deposits.

Jan 9, 1979