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By Stefan Boshkov, Malcolm T. Wane

THE validity and accuracy of velocity measurements underground have been questioned repeatedly by those in mine ventilation work. The general disagreement on the subject is well illustrated in an AIME publication.' Although the presence of errors is readily admitted, their magnitudes are not known and often are described by practical operators merely as "great," "small," or "of no importance." The belief that errors are of academic interest only prevails because of a justifiable claim that actual volumes of air circulated are well in excess of those required by law and safe mining practices. Poor understanding of the source and nature of errors inherent in velocity measurements, coupled with questionable determination of cross-sectional area, result in faulty techniques for the purpose of expediting ventilation surveys and render doubtful the calculated volume. Often consistency of readings is confused with accuracy. A succession of check readings showing a maximum deviation of 5 pct in the measured value of velocity usually signifies nothing more than diligent application of technique in a stable ventilating current. This article discusses the errors involved in air measurements underground. Where instrument errors are presented, the treatment is confined solely to the rotating-vane anemometer, recognized as a most useful ventilation measurement tool because of its simple design and easy operation. In the following pages a positive deviation is defined as one which has to be added to the registered air velocity to obtain the true air velocity.

Jan 1, 1956

By H. K. Martin

IN September 1954 the Lavender pit concentrator at Lowell, Ariz., began treating low grade porphyry copper ore from the nearby Lavender mine. Nominal capacity of the mill is 12,000 tpd, but production now averages 16,226 tpd. Plant design was somewhat affected by the re-use of old equipment and the substantial re-use of old buildings. A breaking-in period between June 24 and Sept. 1, 1954, was devoted to training operators and making minor changes in launders, chutes, and piping. From Sept. 1, 1954, to July 1, 1956, the mill treated 8,598,105 dry tons of ore, from which 556,541 tons of concentrate were produced, containing an indicated 144,055,185 lb of copper.

Jan 11, 1957

By W. F., Netzeband

SEVERAL criteria have been used more or less successfully in finding and developing orebodies in this district. Among them is the relation of the fracture to the orebodies. It has been known for some time that there was some relation, but it has been but recently. that careful study has been given to this subject. Like all the criteria used in this district, this relationship must be used with caution, for what-is true in one part of the district is not necessarily true in another.

Jan 1, 1928

THE third annual Joint Western Mining Convention, held at Los Angeles, Sept. 10 to 13 inclusive, was a notable success both as to attendance and interest. Registration the first day amounted to 201, and the total crept up to 347 before the close. The American Institute of Mining Engineers was well represented, approximately 80% of those registered and most of the speakers being members. This illustrates largely the amount of interlocking membership and the reason for holding at one time and place meetings of the several related organizations. The plan has proved so successful that it is probable that Spokane will extend an invitation for next year that seems likely to be accepted. It is proposed that the convention be timed so as to permit visitors from the East to stop there Oct. 3 to 5, en route to the American Institute of Mining Engineers meeting at San Francisco, Oct. 7 to 9. Simultaneously, it is expected that the Petroleum Division will hold its fall session at Los Angeles, the two streams of travel meeting in San Francisco, just before departure of the party of engineers traveling to Japan to attend the World's Engineering Congress. The Los Angeles meeting opened Monday morning with a general session under the auspices of the Western Division of the American Mining Congress with Philip Wiseman in the chair. After a series of short responses to the welcome extended, Charles W. Merrill discussed the needs of the western mining industry. A complimentary luncheon to members and delegates followed.

Jan 1, 1928

By A. S. Malicsi, R. J. Lipp, I. Iwasaki

A loch-grade copper-nickel deposit, with an estimated 4.6 Gt (5 billion st) and average analyses of 0.6% copper, 0.2% nickel, occurs in northeastern Minnesota. In addition to copper, nickel, cobalt, and precious metals, the Duluth gabbro contains magnetite, ilmenite, olivine, plagioclase, and biotite. It u estimated that flotation tailings that would be produced by a concentrator of optimal size to sustain a smelter would amount to 20 Mt/a (22 million stpy). The flotation tailings, having already been ground, warrant a closer examination for recovery and use of potential byproducts. Residual sulfide minerals and fibrous minerals may also be isolated and treated separately for useful purposes or for disposal in an environmentally acceptable manner. Two flowsheets were developed; one involving preconcentration by low- and high-intensity magnetic separation and another involving preconcentration by gravity concentration. Concentration methods for recovering and purifying individual byproduct minerals were investigated. From their chemical, physical, and mineralogical characteristics, the potential areas of application and marketabilities of each product fraction were surveyed.

Jan 1, 1985

By W. E. Keck, Paul Jasberg

TheRe is a considerable tonnage of iron ore in the Menominee Range of Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a relatively large quantity of finished concentrate would be obtained (deleterious sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal mincrals in a nearly pure state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,0001. Of this quantity and value, Michigan produced approximately 19 per cent1. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1938

By Y. Fukunaka, Y. Kondo, Z. Asaki, S. Nakashita

The pyrite smelting process in which about half amount of sulfur is recovered from pyrite by thermal decomposition in an oxygen-free high-temperature combustion gas flow in the flash smelting furnace is being conducted at Kokkola Works in Finland. A mathematical model of this process was developed, and the rates of thermal decomposition and fusion of suspended sulfide particles in the reaction shaft of furnace was calculated. This model is thought to be appropriate because of a fairly good coincidence of the calculated length of reaction zone with the shaft height of the furnace at Kokkola Works. The calculated reaction zone in which the thermal decomposition and fusion of sulfide particles occur becomes longer when pyrite particles of larger sizes are fed. The feeding rate of pyrite particles and the gas velocity at the nozzle exit are also the important operating factors. These two factors are closely related to the volume fraction and the residence time of suspended particles in the gas stream, and the optimal combined levels of these factors at which the length of reaction zone becomes minimal were obtained.

Jan 1, 1976

By Fred T. Greene

(San Francisco Meeting, September, 1915) MOST of. the recent discussion of the mineral land law published in the Transactions is in the abstract-an exception being Mr. Goodale's paper, The Apex Law in the Drumlummon Controversy,1 which illustrates in concrete instances many of the practical disadvantages of what Dr. Raymond has. called "The Law of the Apex." The present paper, it is hoped, may serve a similar purpose, emphasizing the necessity for a change in our mining laws, and bringing home to mining engineers some of the defects and dangers of our present code. There are many storm centers of "apex litigation" in the Rocky Mountains; and not the least of them is the Wardner camp, where such litigation has been almost continuous since 1892, and the end is not yet. In their decisions, the courts have accepted the claims of the litigants that the " Wardner vein" is a broad zone varying from 250 to 500 ft. in width at the surface. This is the simplest theory which could have been advanced, and probably decreased, rather than augmented, the number of contests; in fact, every one of the claim owners seemed to feel that the greatest advantage would accrue to him if this theory were adhered to. The dominant structural feature of the Wardner vein is a persistent fault, striking N. 40° W., clipping about 40° to the southwest and called the "Wardner foot wall." Fig. 1 is a composite of two adjacent cross-sections of the vein and is a fair representation of the relative size and shape of the orebodies and their relation to the "Wardner foot wall." The country rock is a comparatively thin-bedded sericitic quartzite which has an average strike of N. 80° W. and clips at high angles to the north and south.

Jan 5, 1915

By J. B. Clark, F. N. Rhines

brittlement or notch sensitivity progressively increases. Further, in contrast to results obtained with the impact test, the notch strength for the large specimens does not reveal a 500°F embrittlement range. The notch sensitivity as determined with the 0.3-in. specimen of 4340 steel given the stepped austenitizing treatment has been discussed elsewhere. This quantity as measured for the 1.1-in.- diam notch tensile test and given in Fig. 3, is taken to signify that reduced notch sensitivity is encountered in the 600" to 800°F tempering range for specimens given the stepped austenitizing treatment. The stepped austenitizing treatment may, there- fore, be of use in promoting deeper hardenability for a 4340 steel while at the same time giving reduced notch sensitivity in the high-strength range in which this steel is now being used. Acknowledgments The work reported was supported by the U. S. Navy Bureau of Aeronautics. The authors are indebted to the Bureau of Aeronautics for granting permission to publish results of this research and to N. E. Promisel, H. Hessing, and J. Maltz for their interest.

Jan 1, 1958

By J. M. Davey

Lead-zinc sulphide ores at Mount Isa are currently treated at the rate of 180,000 long tons per 28 day period in the No. 2 Concentrator of Mount Isa Mines Limited. Prior to June 1966 lead-zinc ore was treated in part of the No. 1 Concentrator up to a rate of 70,000 long tons per period. Since 1955, two major changes in ore type being processed have occurred. Because of these changes, problems arising from treatment of the ore have altered and during the period several major changes in practice have been advocated and experimentally tested. Most of these flow sheets were developed with a view to overcoming one major problem in the ore. These were invariably abandoned as the Mount Isa lead-zinc ore contains a number of equally major problems all of which must be overcome in the treatment process. MINERALOGY The orebodies are situated in the Mount Isa Shale Group which is Proterozoic in age (Carpentarian System). The sediments consist dominantly of fine grained dolomitic, quartzo-feldspathic shales and siltstones. Specifically, the Mount Isa orebodies lie in the Urquhart shale formation which is characterised by sediments of high albite and orthoclase content denoting a large volcanic component. The Urquhart shales are approximately 3,500 feet thick and extend at least north and south of Mount Isa for 20 miles in each direction. In the area of the silver-lead-zinc orebodies the Urquhart shales are highly pyritic and have a relatively high carbon content. The

Jan 1, 1970

By R. B. Schluter, M. M. Fine

Development of a process for winning copper from pelletized chalcocite concentrate is underway at the Bureau of Mines, Twin Cities Metallurgy Research Center. The new route from concentrate to metal by which the Bureau seeks to eliminate matte smelting and converting includes a two-stage fluid bed treatment. In the first stage, pelletized concentrate containing 32%Cu and 7% S is first desulfurized to less than 1.0% S in an oxidizing atmosphere. In the second stage, the calcine is metallized by reduction with hydrogen. Thereafter, the reduced product plus 10% CaO is routed to a smelting furnace which separates metallic copper from the gangue. Recovery and Cu content at this point are in the 97-98% range. This product must be refined to remove sulfur and iron so the metal is suitable for making wirebar copper. An important feature of the process is fine concentrate pelletization prior to fluid-bed treatment. This permits a shorter reaction time, a decrease in dusting and easier subsequent processing. In a broad sense, sulfide copper pyrometallurgy is a batch sequence in three separate vessels, i.e., a reverberatory furnace to yield matte copper, a converter to produce blister copper and another reverberatory furnace to produce fire-refined copper. Matte-smelting has remained relatively unchanged since it became a universal practice some 50 to 60 years ago. It is now serving a wide range of smelter feed materials, but many concentrates are not immediately amenable to the process. There are abundant copper resources which lack sufficient sulfur and other elements lo sustain the full chemistry involved in matte-smelting. This necessitates adding sulfur to make the product fit the process, and usually none of the sulfur is recovered. From the standpoint of pollution alone, the development of a smelting technique for low-sulfur concentrates not requiring the addition of sulfur would be a significant gain.

Jan 1, 1970

By R. S. Archer

THE name molybdena was employed by Pliny to denote various substances resembling lead. Later this name was applied to galena-the naturally occurring sulfide of lead-or substances of similar appearance. By the middle of the eighteenth century, it was applied to graphite and to the mineral sulfide of molybdenum (MoS2) now called molybdenite. This confusion is quite understand- able inasmuch as these substances look and feel very much alike. In 1778, the Swedish chemist Scheele published a treatise in which he pointed out essential differences between graphite and molybdenite. On treatment with nitric acid, molybdenite, unlike graphite, produced a peculiar white earth with acidic properties which he called molybdic acid. Since the same mineral gave off sulfurous fumes on heating, he concluded that it was a sulfide of molybdenum. In 1790, there appeared an account of the isolation by P. J. Hjelm of the new element molybdenum, as a metallic powder, by heating the oxide with carbon. It was not until Bertelius conducted the necessary experiments, about 1818 to 1825, that the foundation of the chemistry of molybdenum was laid. The only recorded use of molybdenum during the first century after its isolation was as a chemical reagent, primarily for the determination of phosphorus. It was not until the last decade of the nineteenth century that the use of molybdenum in steel appears to have been investigated. A

Jan 1, 1953

By I. Iwasaki, P. L. De Bruyn

Electrical double-layer properties of the silver sulfide-solution interface in different electrolytes and the influence the properties exert on the adsorption of dodecylammonium acetate (DAA) were studied using an electrochemical titration technique. The flotation behavior of silver sulfide was observed using DAA as collector and the results were correlated with adsorption measurements. Silver and sulfide ions were identified as the potential determining ions and their adsorption densities were measured as functions of the pAg and of the ionic strength at two different pH values. The point-of-zero-charge (PZC) was observed to be at pAg 10.2, the value being independent of pH and of the nature and concentration of the electrolyte used. The surface charge of silver sulfide in these electrolytes was positive for pAg values less than 10.2 and was negative for pAg values greater than 10.2. The adsorption of amine on silver sulfide surfaces at pH 4.7 was found to be strongly dependent on the pAg. A shift in the PZC towards a lower pAg due to the adsorption of amine indicated a specific affinity of dodecylammonium ion towards silver sulfide surfaces. At pH 9.2 a strong adsorption of the undissociated amine molecule was indicated. The PZC shift towards a higher pAg and the adsorption of the amine was virtually independent of the interfacial electrical conditions.

Jan 1, 1972

By P. D. Merica, A. N. Finn, R. G. Waltenberg

CeRtain compositions of the light, i.e., aluminum-rich, alloys of aluminum with magnesium and copper have become quite well known within the past ten years under the name of duralumin. These alloys are used for rolling and forging and can be so treated as to develop quite remarkable mechanical properties. Thus a properly heat-treated alloy containing about 4 per cent. of copper and about 0.5 per cent. of magnesium, rolled into sheet or rod, will have a tensile strength of approximately 55,000 1b. per sq. in. (3866 kg. per sq. cm.) with an elongation in 2 in. (50.8 mm.) of about 15 per cent. This alloy, duralumin, was developed by Wilm,1 and its properties more fully described by Cohn.2, The authors considered it worth while to investigate the mechanical possibilities of the light alloys of two somewhat analogous ternary series; namely, of aluminum-magnesium-nickel and aluminum-magnesium-manganese, to study the effect of variation of composition upon mechanical properties within the alumimum-rich group of the aluminum-magne-

Jan 1, 1921

By W. E. Keck, Paul Jasberg

TheRe is a considerable tonnage of iron ore in the Menominee Range of Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a relatively large quantity of finished concentrate would be obtained (deleterious sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal mincrals in a nearly pure state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,0001. Of this quantity and value, Michigan produced approximately 19 per cent1. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1938

By W. A. Knoll

THE sinking of a new shaft at the Newport mine, Ironwood, Mich., was started in May 1931 and completed on Aug. 3, 1932. During this period, 2665 ft. of shaft in granite was completed, at, an average advance of 6 ft. per 24 hr. In November of 1930, experimental work was con-ducted oil 65 ft. of shaft through 22 ft. of overburden where ledge was encountered, and this work convinced the operators that all drilling could be clone with vertical holes with the blasting relief to a 4 ½ -in. hole drilled vertically in the center of the cut. The reason for not adopting the conventional V-cut was to get away from damaging the shaft steel. The blasting in a V-cut naturally tends to throw the broken material upward, but with the cut as adopted the relief was in a horizontal direction to a large extent. The scheme of mucking employed made it necessary to keep the steel shaft sets within 511 ft. of the bottom at all times. This could not be clone without serious damage with a V-cut when blasting in granite. The cut as drilled also broke 10.53 ft. per round of drilling, which was considerably more than the experience with a V-cut in the sane material. The extended cut reduced proportionately the delays for charging, blowing smoke and handling drilling equipment in the shaft. Another advantage was the ease in drilling vertical over inclined holes, and the preservation of the proper spacing of the drill holes at the bottom of the cut.

Jan 1, 1938

By R. Lyndon Arscott, P. Hackett

This chapter reviews the early stages of a study designed to investigate the physical behavior of the coal measure rocks around longwall panels over a relatively large area. The aim of the work is to attempt to explain a directional tendency for a certain type of underground fracture. The geological structure of the area is reasonably uniform but the effect of some local anomalies is also discussed. Although some definite tendencies have been recorded, the results so far achieved need confirmation by further experiments. The chapter deals first with some in-situ strain measurements carried out in longwall panels and continues with a discussion of the relationships between induced fractures and the natural variations in the structure of the rock mass. Finally, some light is shed upon the gas outburst phenomenon although eradication of the hazard is far from assured. STRESS AROUND A LONGWALL PANEL Considerable progress has been made during the last few years towards the determination of the mechanism of failure of small samples of rock under varying environmental conditions. Much more laboratory testing needs to be done in this field but an even greater amount of study needs to be devoted to the extrapolation of laboratory phenomena to failure around underground excavations. The problem is made more difficult because the stress redistribution around an excavation is often difficult to define, particularly when part of the rock mass fails and a

Jan 1, 1972

By R. L. Curfman

In May 1960, six months after conversion of one- half of the Uranium Reduction Co. mill from acid to alkaline leach, severe corrosion was encountered in the 112 stainless steel wash baskets in the resin- in-pulp portion of the uranium circuit. Fortunately the corrosion was limited to the stainless steel screen cloth and bolts. The frames were not affected. Each resin-in-pulp wash basket serves as a container and a vehicle for approximately 40 cu ft of ion-exchange resin. Four baskets are installed in each tank through which uranium-rich solution flows as the baskets move up and down mechanically in the tank. The ion-exchange resin has an affinity for the uranium in the solution which causes it to be deposited on the resin in solid form. By reverse action with different chemical solutions, the uranium may be stripped from the resin for further processing and purifying. This section is the first step in the actual recovery of the uranium.

Jan 9, 1962

By J. R. Finlay

Every business man who has reached the age of forty, or perhaps even thirty, must know from his own experience that there are occasional periods of "good times'' and others of "bad times "-booms and panics. Those who give to business some complexion of science have invented a semiscientific name for these alternations-the business cycle-indicating that it is a normal phenomenon which by its own nature repeats itself. The longer one lives and the more one enlarges his own experience by the study of history, the more of these cycles he knows and the more disposed he becomes to take their recurrence for granted. If these alternations can be put into the category of common- places, why not treat them as such? We are in a sharp depression right now, why worry about it? Is there not a certain average value for business that can be depended upon in spite of depressions? By way of rejoinder one might answer that war is the great commonplace of history, but when we get into one we generally find it worthy of attention. In the present case, many a man has lost two-thirds of his income, and he is extremely nervous about finding it again. The Southern Pacific Railroad earnings have dropped 75 per cent in the past year; Pennsylvania, 60 per cent; United States Steel Corp., about the same. The drop in current earnings is

Jan 1, 1932

By Robert Linton

IN 1898, Joseph L. Giroux and J. A. Snedaker organized the Pilot Knob Copper Co. and began developing the Pilot Knob mine at Kimberly, Nev., for high-grade copper ores, carrying good gold and silver values that the formation had disclosed. At that time the nearest railroad was over 150 mi. distant. The high-grade ores did not prove to be extensive at this point-at least to the depth. (240 ft.) to which the work was carried-but development of neighboring claims indicated extensive deposits of sulfide porphyry ore of concentrating grade lying at shallow depth, and deeper deposits of direct-smelting oxidized ores occurring in limestone near the limestone-porphyry contact. The properties passed through the hands of several organizations, with only meager development, until acquired in 1913 by Consolidated Coppermines Co., whose holdings now comprise 3480 acres of mining claims in the Robinson district. Since that time development has been prosecuted more actively; and for the purpose of determining the most efficient and economical method of treating the ores, considerable testing work has been done during the past three years, both in the laboratory and in actual mill operations. At first, the shipments were of ore high enough in grade to be profitable even with the long wagon hauls to the railroad and prevailing freight and smelting charges. In 1905, a blast furnace and a concentrator were erected at Kimberly. On account of insufficient ore supply, the blast furnace was never blown in and later was dismantled. The concentrator as originally equipped wag operated for only about two months, both because the ore supply was not sufficient and because gravity concentration did not yield satisfactory extraction. The location and arrangement of the mill further entailed high operating costs. In 1908, the Nevada Consolidated Copper Co. began to mill successfully, on a large scale, its sulfide porphyry ores, which are similar in character to the adjacent Coppermines ores. After that time, all of the ores and concentrates produced by Coppermines Company were

Jan 8, 1920