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By J. K. Brooke, F. A. Renninger

During 1966, crushed stone production in the United States totaled just over 811 million tons valued at almost $1.2 billion. This represented in- creases of 4 % in tonnage and 5 % in value over that for 1965. Excluding the crushed stone used for agricultural and certain industrial purposes (cement, lime and flux), crushed stone mineral aggregate production totaled 616.3 million tons valued at almost $910 million, also up roughly 4% in tonnage and 5% in value over the 1965 figures. Limestone was by far the most widely used rock variety, followed by basalt, granite and sandstone in that order. Concrete aggregate and roadstone continued as the main uses for stone, accounting for 63% of all tonnage produced in 1966 and 60% of total stone value. Sand and gravel production in 1966 increased 3% over that for 1965. Total 1966 output was just in excess of 934 million tons valued at almost $985 million as compared with 908 million tons at $957 million for the previous year. Excluding the higher valued industrial sands, 903.2 million tons of sand and gravel valued at $891.6 million were used directly as mineral aggregates, representing a 2.9% increase in tonnage and a 2.4% increase in value over 1965.

Jan 2, 1968

By L. W. Strock

Metallurgists handling lead and zinc ores have long been familiar with the spectrograph as a routine analytical tool, as its earliest regular use by American industry was in controlling impurities of zinc metal and its alloys. This application has been extended to other metal industries on an extensive scale, accompanied by refinements of procedure to such an extent that a large part of some metals produced, especially magnesium, aluminum and steel, are checked only by spectrographic methods for conformity to specifications. The spectrographic analysis of ores and other poorly conducting powdered solids presents difficulties not encountered with metallic samples, which can be arced or sparked as self-electrodes or can be readily dissolved, so that their solutions can be analyzed, as in the American Society for Testing Materials standard methods for zinc and zinc-base alloys. Spectra of powdered solid samples can be prepared by using carbon electrodes provided with a crater of suitable size, into which the sample is packed. Ore samples and many other powdered solid materials usually analyzed in the chemical and metallurgical laboratory are more complex and varied in composition than samples of metals produced in large tonnages. 'lore preliminary work therefore is usually necessary in devising a spectrographic method for analyzing a given type of powdered sample than for analyzing metal samples, in order to use that method with confidence. The howledge that the standard samples and unknowns produce equivalent line intensities at equal concentration is the fundamental basis of any quantitative spectrographic method. On the other hand, powdered samples have an advantage over metals in that any desired number of chemical compounds can be mixed dry in any desired ratio to produce a synthetic standard. Expcrience has shown, however, that spectra of elements in finely divided compounds introduced into a standard in preparing a synthetic ore sample do not always behave in the electric arc in a manner that produces spectral line intensities similar to those observed at the same concentration in a natural mineral. In ore samples minor elements frequently are contained in the crystal lattice of larger particles of an abundant ore mineral. Their dissociation and volatilization from the sample into the arc then proceeds differently in the standard and sample, with resultant differences in intensity. During the past 10 years I have devised and applied several quantitative spectrographic methods for determining various elements in rocks and minerals in connection with studies on their geochemistry,' but the incentive has gradually changed since the summer 0. 1940 to the specific practical problem of searching for domestic sources of rare and stratcgic metals. The

Jan 1, 1949

By H. C. George

The Wisconsin Zinc District, or the Upper Mississippi Lead and Zinc District as it is often called, lies in the southwestern corner of Wisconsin, in Grant, Iowa and Lafayette Counties, and it includes adjoining parts of Illinois and Iowa. The district is about 70 miles long, north and south, and about 40 miles wide, east and west. It lies wholly within what is geologically known as the non-glaciated area of the Upper Mississippi Valley. HISTORY OF THE DISTRICT The district was first opened up as a lead producer in 1822. From this time until 1860, about 205,000 tons of cog lead (galena) and washed lead (galena) was produced from shallow crevices and openings. From 1860 to 1900, about 74,500 tons was produced, and since that time, from 5000 to 7000 tons has been produced annually. Since 1900, most of the lead concentrate produced has been as a byproduct of the zinc mines. The first zinc ores were mined about 1862. These were the carbonate ores, locally known as "drybone." Very little zinc blende was mined in the district, previous to 1875. The zinc blende ores mined from 1875 to 1900 were mostly of the high-grade, hand-cobbed, sheet-ore class, which usually contained from 45 to 60 per cent. metallic zinc Such mines as the "Sallie Waters," "Quinlin," 'Lead Mine," "Benton Blende," and "Ida Blende," located near Benton, Wis., were mines which produced ores of this type, during this period. The mines located at Highland, the "Coker Mine" located at Livingston, Wis., and the "Opencut Mine" located at Shullsburg, Wis., were mines that were heavy zinc carbonate producers, previous to 1900. The production of zinc ores in the district from 1862 to 1890 was about 283,500 tons, mostly zinc carbonate, with a probable average metallic zinc content of 30 per cent. From 1890 to 1903, the production

Jan 1, 1918

By Joseph S. Malesky

The discovery and development of explosives mark one of the most important findings in the history of civilization. Without explosives our vast economic enterprise concerning the mining of coal, copper, iron, aluminum, and various other ores could not function. Explosives are used in all kinds of construction works, in the razing of old buildings, blasting of trenches, driving of tunnels, and in many other instances common to our everyday life. For these reasons explosives are rightfully referred to as the forerunner of progress. An explosive may be defined as a substance (usually a mixture) that, when flame or shock is applied, yields readily to rapid combustion or oxidation, accompanied by the formation of such relatively large quantities of gases as to produce much violence and pressure which, in turn, react against their surroundings and cause what is termed an explosion. By their very nature the action of explosives is destructive and disruptive of adjacent materials. Decomposition of explosives can occur through deflagration, which is rapid burning or combustion, as in the case of black powder, or through detonation, which is an almost instantaneous disruption, as in the case of dynamites and blasting agents. HISTORY OF BLASTING WITH EXPLOSIVES At one time workmen obtained stone blocks for building by grooving the rock with crude picks, driving wooden wedges into niches in the rock, and pouring water on the wedges; the swelling of the wood forced out the blocks. As late as the 17th century, fires were placed against the face of rock to crack it, and water was sometimes dashed on the heated rock to shatter it by sudden cooling. The progress of our country is synonymous with advancement of the improved manufacture and extended use of explosives. Coal had been

Jan 1, 1981

By J. Grosso, D. J. Nagel

In many metallurgical studies, it is necessary to reveal the composition and structural properties of materials. Usually this is done by etching, but some substances do not etch well or easily. Anodizing is known to provide an alternate treatment in many cases. In general, this technique is simple, often more sensitive to composition differences than etching, has excellent resolution, and provides variable contrast in those elements and alloys which anodize. Here we report the use of anodizing in diffusion studies in the TiCb system. Fig. 1 shows a cross section of the diffusion zone in a TiCb couple. The anodizing has clearly revealed both composition and crystallographic features. The maximum bulk penetration of the titanium into the columbium is marked by a sharp line because of the steep concentration gradient. The titanium grain size and orientation differences are also evident. Variation in the grain size reflects the gradually decreasing columbium concentration.

Jan 1, 1967

A1 in carbon steel, equilibrium temperature, XLVII, 740-747. A2 and A3 in pure iron, critical ranges, XLVII, 665-739. Abbott, Ai Arthur: [biog. notice, Bulletin No. 27, Mar., 1909, xxvii]; death, XXXIX, . [xl]. Abbott, Arthur Vaughan: [biog. notice, Bulletin No. 16, July, 1907, 6581; death, XXXVII, [xxxix]. [ ]

Jan 1, 1918

By James D. McClung, H. J. Gluskoter, M. R. Geer

INTRODUCTION The purpose of coal preparation is to improve the quality of coal to make it suitable for a specific purpose by (1 ) cleaning to remove inorganic impurities; (2) sizing-crushing or screening, or both; or (3) special treatment, such as dedusting. The properties and quantities of impurities in coal are of major importance in the design and operation of steam generating equipment. Al- though boilers are often designed and equipped to use a wide range of coals, no boiler will perform equally well with all types of coals. All coals have certain properties that place limitations on their most advantageous use. These limitations are especially stringent for many of the older installations. Because of a general lowering of quality of raw coal in recent years, the need for coal cleaning has significantly increased. Among the factors contributing to the need for increased coal preparation are (1) increased demand for quality brought on by market and environmental requirements; (2) increased extraneous dilution caused by mine, health, and safety laws; and (3) depletion of the higher-quality coal seams.

Jan 1, 1979

By P. D. Frost, H. A. Robinson, J. R. Doig, M. W. Mote

The mechanism of hardening in heat-treatable zirconium alloys was foUNd to be analogous to that for titanium alloys. Zirconium containing a relatively large addition of a ß -stabilizing element such as molybdenum or columbium can be hardened by the following transformation: Lean alloys, having insufficient alloy content to retain ß at room temperature are hardened by the following transformation: Application of these findings in Zr-Mo-Sn and Zr-Nb-Sn alloys produced strengths as high as 190,000 psi with reasonable ductility. PRIOR research on zirconium alloys has been concerned with development of greater strengths and creep resistance by solid-solution hardening or by dispersion hardening. Although solution and aging heat treatments had been applied earlier to zirconium alloys, quenching frequently produced low ductility. The possibility that the ß-to-w transformation, discovered earlier in titanium alloys,' might also occur in zirconium alloys and cause low ductility was considered, and, indeed, was found as predicted2 to be the case. In the earliest experiments, the heat-treatment response of titanium, too, was disappointing. However, by avoiding the formation of the embrittling w phase, it became practical to obtain room-temperature strengths higher than 180,000 psi, with elongation values of 10 pct.3 Based on the present concept of titanium heat treatment, the principal requirement for a heat-treatable zirconium alloy is that it contains a certain minimum amount of one or more ß -stabilizing elements. Only molybdenum, columbium, and tantalum, when present in sufficient amounts, are known to stabilize ß zirconium to room temperature during rapid cooling from the ß field. Tantalum was undesirable because of its high thermal-neutron cross section. Aluminum and tin are effective a stabilizers, but aluminum has been shown to seriously decrease the corrosion resistance of simple zirconium alloys in hot water. Therefore, for the present study, tin was used as the stabilizer addition. The alloys selected for this evaluation are presented in Table 1 along with their analyses and ß-transus temperatures. The analyses indicated that intended compositions were usually realized. EXPERIMENTAL PROCEDURES All of the alloys were melted from sponge zirconium and fabricated to sheet for heat treatment

Jan 1, 1960

By Stephen Krickovic

THERE is today no proven continuous mining machine that can be used under all the varying conditions found in most bituminous coal mines. During the last five years, however, both the machines and methods of using them have been improved. Coal operators can now exercise a fair degree of selectivity, except those who must struggle with thick and hard partings and operate in seams less than 40 in. thick. It must be realized, then, that more than one type of continuous miner may be used advantageously in the same coal mine. Although this appears to violate the standardization generally sought after, the gain can more than offset added maintenance and, to a lesser degree, operating problems. It is equally important to realize that most coal mines will require one or more conventional loader setups in the plan of total mechanization. Seam variations, adverse physical conditions, and special designs of main headings for haulage and ventilation, to name only three reasons, may render 100 pct use of continuous miners uneconomical. Of course, this situation may change. In one mine, prior to 1954, machines that ripped coal from the face achieved only average results, as compared to the impressive performance of boring-type units in another coal mine. A boring-type unit was therefore selected for the first mine in the belief that the chance of success would be greater if it were used in a combined cutting and wedging operation, cutting a full face in its forward movement. The miner was located in a part of the mine where a special projection could be readily developed, a solid area scheduled for mining according to the overall progress plan. All openings surrounding the particular area were carefully investigated for the presence of sulfur balls. Fig. 1 (opposite) shows the representative seam section, containing the several pyritic bands 1/4 to 1/2 in. thick; a characteristic Pittsburgh seam parting averaging 5 to 6 in. of slate, coal, and slate; and the occasional py-rite lenses 2 to 3 in. thick. Under normal conventional mining methods, the top 10 or 12 in. and the bottom 4 in. are left in place to offer roof protection

Jan 1, 1958

By William Marsh Baldwin

THE ROLLING OPERATION proper is applied to metals and alloys not only in the production of flat products but also in the production of shapes, rods, wire and even in specialized forms in the production of tubes. The present discussion of rolling copper and copper alloys will be [ ] limited to a consideration of rolling flat products such as strip, sheet, foil, plate, and others. In this case (as in the others listed above), the rolling operation itself is only part of an integrated sequence of operations. In Fig I such a sequence going to make up a brass strip mill is sketched out. It is seen that the rolling opera-

Jan 1, 1948

By C Gunther

The classification here used is one of convenience only; it is not intended to include all known types of ore deposits. The characteristic features of the several well-marked types of primary mineralizations are described without reference to the ultimate source of their metals. The minerals of many deposits of obscure origin were probably introduced through fissures that are now healed, or are due to the migration of metals from such deposits. It is not within the scope of this book to enter into a general discussion of the genesis of ore deposits but, in view of the progress being made in our comprehension of the conditions under which ore deposits were formed, mention should be made of recent work. J. E. Spurr's two volumes, "The Ore Magmas," are recommended as crystallizing the views of those who are inclined to ascribe the origin of most ore deposits to a differential precipitation from magmatic rock masses and to the migration and precipitation of the viscous, liquid or gaseous exhalations from those masses. He has especially emphasized the role

Jan 1, 1932

By William J. Douglas, Jack T. Urie, Randall D. Metz

Production and financial planning for a new underground mine requires the coordination of equipment and coal reserves in a manner which assures that resources are utilized efficiently in achieving the target mine production. It is necessary to establish the productions which are attainable at the section level during different mining operations (advance, retreat, development) and under different mining conditions (roof, seam height, resource quality). It is also necessary to identify the interactions between production plans and ventilation equipment So that operations can be carried out without disruptions caused by inadequate ventilation. A set of computer models has been applied in planning a number of new coal, oil shale, and phosphate mines. A critical path production model, CPMINE, was used to determine face production levels for different cut sequences and seam heights, taking into account machine performance characteristics and operational availabilities under these varying conditions. The results formed a production data base for use in the mine sequencing model, MPLAN. This model processes each of the segments of a user-defined mine sequence network (strategy tree) taking into account the equipment available for mining operations and the previously determined production scheme devised by the mining engineer. Mine ventilation was analyzed with an expanded version of the Penn State MVS Ventilation model to determine fan and ventilation shaft requirements for supporting alternative production strategies. The MCOM mine cost analysis model has been applied to evaluate the economic performance of mining alternatives. The results of these studies were used to make decisions relating to equipment selection and acquisition schedules for both room-and-pillar and longwall mining systems. The approach and procedures which were used during these studies are described.

Jan 1, 1983

Jan 6, 1976

By Barbara A. Thompson

A previously reported high-resolution method for the location of boron-rich areas in metallurgical and biological specimens was been adapted for general use on a routine basis. The rnetlzod utilizes neutron activation and autoradiograpizy. Alpha-particles emitted by boron nuclei upon neutron capture are recorded on a photographic emulsion. The resulting a-particle tracks show the location of boron-rich areas. Experimental techniques, interferences, and limitations of the method are discussed in detail. The method is most useful where there is marked segregation of boron. In this type of sample, the segregation can be observed when the nominal boron concentration is as low as 0.0006 pct. THE positive identification and location of boron-rich areas in metals is frequently of great interest in metallurgical work. Unequivocal identification is often difficult to make by conventional metallo-graphic methods. Recently, a method has been described which accomplishes this objective by neutron activation and autoradiography.l-3 The method can be described briefly as follows. Upon neutron capture, a -particles are emitted by boron nuclei according to the following reaction: ,Blo + n - ,a4 + 3Li7 + 2.4 mev The energy is dissipated as kinetic energy of the products. By irradiating a boron-containing sample in contact with a photographic emulsion and subsequently developing this emulsion, a-particle tracks are obtained whose location corresponds to the location of boron-rich areas in the sample. Two factors combine to make the reaction extremely specific for boron. The first is the unusually high (755 barns) cross section of boron for thermal neutron capture. The second is the higher neutron energy required to produce (n, a ) reactions in essentially all other nuclei except lithium. These two factors make the method specific for boron by six to seven orders of magnitude when a predominantly thermal neutron source such as the Brookhaven reactor is used. The reported limit of detection of this method is of the order of 0.01 pct B., The present work was originally undertaken to determine whether this limit could be lowered by use of a thinner emulsion. However, initial experiments showed that in order to use the method at all, it was necessary to reestablish the optimum experimental conditions in terms of the available irradiation facilities. It is the purpose of this paper to describe these experimental conditions in detail, to discuss the factors influencing sensitivity, and to evaluate several techniques for increasing sensitivity. EXPERIMENTAL A) Preliminary Experiments—The first measure-ments were made using samples of crystal oriented silicon steel containing various concentrations of boron. In the later experiments, samples of various high-temperature alloys such as M-252, hcoloy 901, Nichrome V, and so forth, were used. Faraggi, et al.,2 reported that the lower limit of sensitivity in this type of sample was about 0.01 pct B using nuclear emulsions of 50- u thickness. but that it should be possible to extend this limit by the use of thinner emulsions. Accordingly, we first used Kodak Auto-radiographic Stripping Film (Permeable Base) which has an emulsion thickness of only 5 µ. This was mounted on the metallographic specimens according to the technique described by Boyd.4 The emulsion remained in contact with the metal surface throughout exposure and development. Since the emulsion is transparent after development, the autoradiograph and metal surface can be viewed simultaneously and any correlation between film blackening and structure of the metal can be made directly with no problems of realignment. Because the silicon steel is readily attacked by moisture alone, it was necessary to apply a protective coating to the metal surfaces before mounting the emulsion. The coating was made extremely thin in order to absorb as few a-particles as possible. Boyd4 and Gomberg5 have discussed various plastics used for this purpose; however, none was sufficiently impermeable to prevent chemical attack of the steel during the developing process. This attack resulted in the production of gross chemical artifacts in the emulsion. It was, therefore, necessary to use the method of Wolfsberg and John6 as follows. A very thin (approximately 1 µ) coating of Plexiglas II was applied by dipping the sample in a 2 pct solution of Plexiglas II in dichloroethylene. Then, because the emulsion will not adhere to Plexiglas 11, a thin coating of Parlodion was applied in a similar manner using 2 pct Parlodion in iso-amyl acetate. No protective coating was necessary with the high-tem-

Jan 1, 1961

Jan 1, 1898

NEW MEMBERS The following list comprises the names of those persons who became members during the period Aug. 10 to Sept. 10, 1914: Members ALLEY, HARRY MCCAMMON, Mill Foreman .... Churchill Mining Co., Wonder,2 Nev. AMBLER, J. OWEN, Met..; ... Calumet and Arizona Mining Co., Douglas, Ariz. ANDERSON, JAMES WILLOUGHBY, Duell, Warfield and Duell, 2 Rector St., New York, N. Y. ANTISELL, FRANK L., Asst. Supt Raritan Copper Works, Perth Amboy, N. J. CARRINGTON, FRANK GAMBLE, Sec'y and Asst. Mgr., Standard Foundry Co., Anniston, Ala. CONKEY, CHARLES ROLLAND, Structural Draftsman, Barnett McQueen Co., Ft. William, Ont., Canada. COOK, PAUL RICHARDSON, Mill Shift Boss, Buckhorn Mill and Cyanide Plant, Buckhorn. Nev.

Jan 10, 1914

By Paul E. Dorr, Kenneth P. Pavlich

This paper covers the practical aspects of economic analysis of mineral ventures and the application of a publicly available computer program. The paper touches briefly on the time value of money concepts and the phases of project evaluation. The most comprehensive port ion of the paper deal s with the requirements for economic evaluation, including capital expenditure categories, operating expenses, required geological and engineering data, and tax considerations. Highlights of the 1981 and 1982 tax laws are covered. A case study using the MINECO computer program will be used to illustrate the economic evaluation concepts developed. Guidelines and goals of sensitivity analysis and Monte Carlo simulation will be discussed and demonstrated on the MINECO example. The MINECO software system will be displayed as an example of a "user-friendly", interactive, and flexible computer tool available to the mining professional today.

Jan 1, 1983

NEW MEMBERS The following list comprises the names of those persons who became members during the period Apr. 10 to May 10, 1915: Members ADMAN, WILLIAM, Supt., Susquehanna Coal Co Lykens, Pa. BARTH, CARL G., JR., Min. Engr 6151 Columbia Ave., Philadelphia, Pa. BOOTH, ERIC EDWIN, Min. Engr., Mount Elliott Mine, Selwyn via Cloncurry, North Queensland, Australia. BOYDELL, HARRY CYRIL, Asst. Mgr., Randfontein Central Gold Min. Co., Box 42, Randfontein, Transvaal, South Africa. BRADY, SAMUEL HOWARD, Mine Supt Bohemian Club, .San Francisco, Cal. Buses, HARRY EDWARD, Mine Supt., Engels Copper MiningCo Keddie, Cal.

Jan 6, 1915

By J. L. Christie

A recent case of failure of a-low karat gold alloy by stress-corrosion cracking is of interest because it illustrates a principle frequently overlooked: the relation between high residual stress and high yield point. The alloy contained Gold, per cent 39.6 Copper, per cent 51.1 Silver, per cent 5.2 Nickel. per cent 3. 1 Zinc, per cent 1.0 Tension tests on the alloy showed the following:

Jan 1, 1945

By W. A. Backofen, F. de Kazinczy

FRACTURING under conditions of particular interest is identified with the junction of curves relating tensile yield and fracture stresses to test temperature; the intersection point gives the lowest stress, for brittle fracture (at the ductility transition temperature). An expression for is found in Cottrell's brittle-fracture analysis, Eq. [15],1 while measurements of this stress and temperature have been reported for a low-carbon steel heat treated to differ-

Jan 1, 1962