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By Charles A. Ashburner

[The statistics contained in this paper were collected for the United States Geological Survey and communicated to the Institute, by permission, prior to their publication in the report on the Mineral Statistics of the United States for 1887.1 The total coal-production of Alabama in 1887 was about 1,950,000 short tons, the spot-value of which, at the mines, was $2,535,000. The coal-regions of the State lie in the extreme southern part of the Appalachian coal-field, the northern part of which lies along the western New York-Pennsylvania State line; between these limits, New York on the north and Alabama on the south, portions of the

Jan 1, 1889

Copper ores from small mines in the area south of Tucson, where the Twin Buttes mine is located, were first operated in the 1880's. Today this area is one of the great copper mining centers of the world. In 1963, Anaconda Company acquired the property from Banner Mining Company and in recent years joined with AMAX in a 50/50 partnership to work the Twin Buttes property. From the beginning, Anaconda had relied on conveyors to remove overburden, oxide material for eventual leaching, and ore from the open pit. In the large st preproduction stripping program in mining history, Anaconda in a four-year period (1965 to 1969) removed 266 million tons of overburden of an average depth of 500 ft (152 m) lying over the ore body. The alluvium overburden was stripped by scrapers carrying 70 to 80 tons and push-loaded by two D9 tractors operating in tandem. The scrapers delivered their loads to bins which fed a 60 in. (1.52 m) conveyor having a capacity of 8500 tph. The 25% slope belt conveyor, which was 2100 ft (640 m) long, transported the material to the brow of the pit, where it was transferred to an 8300 ft (2530 m) surface belt to a 1000 ton loadout bin. At this point, the overburden was trucked to the sites of the tailings ponds, where it was used for dam construction. During 1976, the one billionth ton of overburden was removed from the Twin Buttes mine. The Twin Buttes quartz monzonite porphyry contains only scattered mineralization of which chalcopyrite is the most abundant mineral, associated with chalcocite, covellite, minor bornite, and several oxide minerals. Oxidation has progressed to variable depths of up to several hundred feet below the base of the alluvium. Because of the depth of the sulfide and oxide ores and hard rock waste, two in-pit crushers and conveyor systems were also installed for their transport out of the pit; and in 1976 a third crusher and conveyor system was installed lower in the pit for waste rock only. The two initial crushing and conveying systems were designed to handle any of three functions: crushing waste to be disposed of by a rail-mounted stacker -conveyor, crushing oxide ore for conveyor and then truck transport to stockpiles for future leaching, and primary crushing of sulfide ore for conveyor transport to the two 30 in. by 70 in. (0.76 by 1.78 m) secondary crushers and the two 7 ft (2. 13 m) standards and four 7 ft shortheads in the third and fourth stage crushing plant. A third standard crusher has been in- stalled recently. Mining is done by 15 yd (11.5 cum) shovels which load 100- and 150-ton

Jan 1, 1978

By A. L. Mular

The flotability of crushed zinc oxide pellets which were doped to produce more n-type or less n-type (more p-type) properties was studied with a Halli-mond tube. Flotation data are presented to show that the pH at which 50% recovery occurs and the collector concentration for 50% recovery depends upon the concentration of doping agent added substitu-tionally for zinc in zinc oxide. The time of sintering of pellets has a slight effect on flotation behavior. A speculative model is proposed to explain the observed behavior in light of the fact that zinc oxide is a semiconductor and has a space charge region at the surface. Experimental verification is necessary before the proposed model can be established as correct. In recent years, the attachment of flotation reagents to minerals has been shown to depend upon the behavior of an electrical double layer which exists in the liquid near the mineral-liquid interface.' Thus, a mineral placed in water will undergo a surface re-arrangement, most likely be preferential dissociation of lattice atoms or by surface adsorp-tion-desorption reactions, to form a dissociation electrical double layer with the solution. Among the many factors which influence adsorption processes, the past history of the mineral itself is one of the most important. Because of trace impurities, minerals from different localities may exhibit marked differences in flotation behavior. This is not unexpected, since investigators who have studied the detailed structure of the double layer's3 have known for some time that the impurity content of many minerals may exert strong influence on double layer variables. For this reason, their studies were usually made with minerals of high purity. The precise relationship between impurities in a mineral and double layer parameters such as capacity and electrostatic potential has been obscure. However, impurities in a semiconductor type mineral which is in contact with a solution have been recently shown to produce changes in the properties of a space charge layer which extends into the bulk of the semiconductor to a distance of one micron or more.4 The double layer is influenced by the space charge layer, whose origin is best discussed in terms of the band theory of solids. A qualitative description of the behavior of impurities in the bulk of a semiconductor, from a chemical point of view, is useful at this point. Briefly, impurities or defects (lattice vacancies, interstitials, etc.) in semiconductors such as PbS, ZnS, FeS2, Cu2S, NiS, NiO, Fe2O3, ZnO, CdS, MnO2 and many others, behave somewhat like acids or bases in water. For example, water dissociates into hydrogen and hydroxyl ions according to

Jan 1, 1965

By Garth M. Crosby, F. McIntosh Galbraith, Bronson Stringham

THE Hercules mine is located in the northeastern section of the Coeur d'Alene district, approximately 1 1/2 miles north of the town of Burke, Idaho. Surface indications of the ore deposit were first discovered in 1886, but regular mine production was not started until 1902 and was continuous until April 1925, when the known ore had been extracted. Incomplete records show that from 1912 until operations were suspended the mine produced 2 1/2 million tons of ore containing 9.4 pct lead and 7.7 oz of silver per ton, together with an estimated 2 pct zinc, 0.3 pct copper, and 20 pct iron. This operation was the first in. a series of mining enterprises culminating in October 1947 with the consolidation of Day Mines, Inc. In the same year it was decided to unwater the levels below the collar of the Hercules shaft in the hope of finding some indication of a recurrence of ore. The unwatering operation has been described in a. previous paper.' The initial exploration, following recapture of the workings, showed sufficient promise to warrant a detailed study of the mineralogy with modern techniques. The general geo1ogy of the Coeur d'Alene district, including a detailed description of the rock types encountered, has been comprehensively treated by Ransome and Calkins' in their classic paper, and only local background description, therefore, is felt to be appropriate here. The Hercules deposit transects a portion of the trough of a broad south-trending synclinorium which has been greatly complicated by faulting. More locally, it lies within a block of ground bounded on the east; by the O'Neil Gulch fault, a steep north-south overthrust of considerable magnitude, and on the west by a monzonite stock, the outcrop of which is 1/2 mile or more wide and 5 miles long. The country rock is composed of thin to medium-bedded argillites and argillaceous quartz-ites of the Prichard and Burke formations, the oldest members of the Pre-cambrian Belt Series of sediments in the area, believed to be of Algonkian age. The contact between them is a conformable gradation. The argillite is colored gray to tannish-gray and is fine-grained, compact, and generally massive in structure. Under the microscope the unaltered argillite is seen to be composed principally of anhedral quartz and a few feldspar grains which were at one time presumably partly rounded sand grains, but as a result of recrystallization and cementation by silica, the interstices are now almost obliterated and quartz grains show crenulate boundaries. The sizes of these crystals vary from 0.5 mm down to 0.1 mm in greatest dimension. In all specimens sericite comprises 10 to 20 pct of the rock and is present abundantly between most of the grains as flakes or shreds which vary considerably in size. Sometimes they form a fine felt-like mat or aggregate, and sometimes flakes are seen which appear to be good muscovite. In some specimens, separated rhombic-shaped carbonate grains are abundant, and in some instances these have been changed to sericite. Mining operations to date have explored the Hercules vein to a maximum vertical depth of 3600 ft below its outcrop, and along a maximum strike-length of 3600 ft on certain of the lower mine levels. The main orebody is irregular in outline, extending over a variable strike-length of 400 to 1500 ft; and it is intersected by a strong transverse fault that has been traced from the surface to the bottom level. This has been named the Hercules fault, and apart from the vein itself, it is the most prominent structural feature in the mine. There is good evidence that it existed prior to the introduction of ore solutions and may have influenced ore deposition, but it was also the locus of important post-ore displacement and shows a progressive right-handed horizontal component reaching 200 ft on the deeper levels. Its vertical component is not definitely known but may be considerably greater. The fault strikes 20° N to 50° E and dips westerly at angles of 70" to 45", flattening in dip where it crosses the original orebody from east to west between 1000 and 1600 ft below the surface. At about 3000 ft in depth the Hercules fault is joined by a vertical fault of similar strike, and the major post-ore dis-placement below their junction is taken up along this vertical branch of the structure, now called the Mercury fault. Recent work has been concentrated in this vicinity. Another structural feature of special geologic interest, though of little economic importance, is the occurrence of a porphyritic dike in this area. This lies a short distance above the Hercules fault, essentially parallel to it, and is 5 to 15 ft in thickness. It appears at first glance to cut the mineralization, suggesting push-apart relationship, but small stringers of the vein minerals have been observed to penetrate the dike for a matter of inches at several points. The dike is thought to be related to the monzonite intrusion. A vertical longitudinal projection of the mine is shown in Fig. 1, which illustrates most of the features discussed above. The Hercules vein was deposited along the course of a strong, persistent shear zone that now appears as a braided network of gouge seams running through more or less crushed and shattered country rock. It strikes 70° N to 80° W and dips southerly at an average of 75". Barren parts of the structure vary in width from less than 1 ft to more than 15 ft. The width of mineralized segments may be double that. Although the evidence is not conclusive, pre-mineral, normal movement along the zone may be 1000 or 1500 ft. The horizontal component is unknown. Post-ore movement appears to have been

Jan 1, 1954

By R. R. Knuckey

HAVING been associated with the operation of the de Vooys process for coal, which has treated 13,000,000 tons per annum, and recognizing the process as of value in ore sorting, Huntington, Heberlein and Co. Ltd. (Great Britain) in 1936 made an examination of all other existing methods. In none of the pioneer applications had recognition been given to the necessity for maintaining certain conditions that are essential for sorting certain ores if a truly efficient separation by gravity alone is to be assured. Consequently, in 1936-1937 Huntington, Heberlein and Co. Ltd., with Pearson, employing certain ideas connected with the de Vooys application, commenced the development of a separator that would allow conformance with optimum conditions in the zone where separation is effected. Later, Holt and Wade added to the value of the original application by Wuensch, Rakowsky and others, whose conceptions are being successfully operated today. Meantime, Trostler had enhanced the value of the original H-H. process by improvements that are now embodied in operating plants, and today the process incorporates an improved apparatus and a stable medium that produce the optimum conditions for separation. These conditions are: 1. Elimination of disturbing currents in the separating zone; 2. Reduction to a minimum of medium-density differences throughout. the separating zone; 3. Stable medium of minimum viscosity to permit the unretarded fall of mineralized particles; 4. Removal of products of separation with minimum disturbance to the separating zone. DESIGN OF SEPARATOR The H-H. sink-and-float separator consists of a pyramidal tank in which the separation actually takes place, connected at the bottom with an inclined bucket elevator. The tank and the elevator are filled with medium to within a few inches of the top of the tank. Medium is fed into the separator at a variety of points, according to the type of ore being treated, and it is withdrawn from the separator at two points: (1) together with the float product, by means of a variable-speed paddle, at the surface of the medium, and (2) by flowing over an adjustable weir cut in the side of the elevator casing. The prepared ore is fed onto the surface of the medium. The intermediate paddles, which revolve at a slow speed of 2 to 5 r.p.m., move the floating ore across the bath from feed end to float-discharge end. The ore, which is heavier than the medium, sinks below the sweep of the paddles and reaches the boot of the bucket elevator, which discharges it without disturbance of the separating zone. These arrangements for withdrawing medium from the separator allow the use of minimum flows, which connote minimum

Jan 1, 1943

By J. R. Thoenen

IF ASKED whether limestone production was a mining problem I would; not hesitate to answer emphatically in the affirmative. The question, "When is a quarry a mine?" is familiar. The immediate mental picture induced by the thought of limestone production is that of an open quarry. All are familiar with the open pit in the iron-producing districts of Minnesota and Michigan and the open cuts of the so-called "porphyry" coppers of the West. If these are mines, they differ little from limestone quarries in general mode of operation; if quarries, why do they need the attention of mining engineers? During 1923, the United States produced in round numbers 70,000,000, tons of ore. The limestone production of the United States for the same period was something over 100,000,000 tons. In tons, it about equals the oil production of the United States. The uses of limestone are legion. A paper read by a prominent engineer of Chicago, at the meeting of the National. Crushed Stone Association held last February in St. Louis says: "There is no industry in the United States today that is more basic in its operation or by itself controls. more industries. There is hardly a chemical operation, hardly a metallurgical operation or building operation that a crushed-stone man does not control if he will jump in and make the full utilization of it." Some of the many uses are for road metal, concrete, railway ballast, building stone, riprap, and rubble, the manufacture of iron and steel, alkalies, calcium carbide, magnesia, carbolic and carbonic acids, asphalt filler, mineral wool, poultry grit, sulfuric acid, phosphates, nitrates, soap, baking powder, the purification of copper and prevention of coal-mine explosions, to say nothing of the quantities used in the making of lime and cement. It has been said that without iron we would revert to the Stone Age; how much iron would we have without limestone? From the point. of view of the mining engineer, using the term in its broad sense to include geologists and metallurgists, the production of limestone is important because of its occurrence, volume, commercial importance, and the problems presented by its recovery and treatment.

Jan 2, 1925

By H. W. Ahrenholz

Seven weeks of 1971 were devoted to a nationwide coal walkout resulting in lost production of some 70 million tons and leaving 1971 coal production at about 550 million tons. Compounding the problem, consumption of coal in 1971 by electric utilities rose by about 5% to 336 million tons. In the mean- time, numerous contracts were awarded for coal R&D including $24.8 million given by the Office of Coal Research to Bituminous Coal Research for the construction of a coal-to-gas pilot plant using the BIGAS process. Exports declined mainly due to Japan's decrease in steel production and to that country's increase in coal imports from Canada and Australia. The advances in equipment design and mining procedures made 1971 a noteworthy year. Introduction of the variable pitch I dipper, the trend toward wheeled vehicles, the greater use of scrapers in reclamation and battery-operated vehicles and oscil-mining, and the increased activity in the areas of ventilation and dust control were given widespread approval. There were also strides made in computerization, longwall mining, roof bolting, rock dusting, mine haulage and methane detection.

Jan 2, 1972

By E. R. Parker, E. A. Smith

Metallurgists and engineers have always been interested in the mechanism of high-speed deformation because metals are rapidly deformed in various applica-tions and manufacturing processes. The deformation of metals by impact loads has recently engaged the attention of a number of investigators. Many of their results have not been disclosed but some of the published investigations1-8 have shown that the tensile strength, yield strength and elongation generally increase with increasing strain rate. The investigation reported herein is an attempt to determine the reason for this increase in strength and elongation. found to depend upon the strain rate. In the bars broken at high speeds, the slip bands appear to be more numerous. This might account for the higher strength as well as the greater elongation. Experimental Procedure Single crystals of copper (approximately 99.98 per cent) were made in graphite molds by the conventional method of lowering the mold out of the hot zone of a hydrogen furnace at a rate of one inch per hour. Solidification progressed from the bottom upward, forming a single crystal. The crystals were about 0.30 in. in diameter and 4 in. long. They were

Jan 1, 1944

By E. A. Smith, E. R. Parker

Metallurgists and engineers have always been interested in the mechanism of high-speed deformation because metals are rapidly deformed in various applica-tions and manufacturing processes. The deformation of metals by impact loads has recently engaged the attention of a number of investigators. Many of their results have not been disclosed but some of the published investigations1-8 have shown that the tensile strength, yield strength and elongation generally increase with increasing strain rate. The investigation reported herein is an attempt to determine the reason for this increase in strength and elongation. found to depend upon the strain rate. In the bars broken at high speeds, the slip bands appear to be more numerous. This might account for the higher strength as well as the greater elongation. Experimental Procedure Single crystals of copper (approximately 99.98 per cent) were made in graphite molds by the conventional method of lowering the mold out of the hot zone of a hydrogen furnace at a rate of one inch per hour. Solidification progressed from the bottom upward, forming a single crystal. The crystals were about 0.30 in. in diameter and 4 in. long. They were

Jan 1, 1944

By T. J. Whalen, M. Humenik

The liquid surface tension of copper-nickel ad copper-nickel-titanium-carbon alloys and the wettability of titanium caybyde by these alloys have been measuhed. It was found that the surface tensions of the binary copper-nickel alloys Lie on a smooth curve between the end members, copper and nickel. The addition of small amounts of titanium and carbon has nO effect on the surface tensions of copper-nickel alloys. Small additions of nickel to copper significantly reduce the contact angle of Ike alloy with titanium carbide. From a Gibbs treatment, nickel is shown to be adsorbed at the titanium carbide-alloy interface. X HE microstructure of two-phase materials has been shown to be influenced largely by the interfacial energies between the phases present.' , In systems prepared by powder metallurgy techniques and densi-fied in the presence of liquid phase, a precise analysis of microstructure and interfacial energy relationships requires a knowledge of the solid-solid interface energies and liquid-solid interface energies. However, marly metal-nonmetal systems are characterized by the "sweating" of the liquid during sintering, and in these systems wettability is a principal consideration. The wetting in turn is dictated by the various interface energies of the system, as shown in Fig. 1 for a liquid drop formed on a solid substrate. The equation which expresses the vectorial balance of surface forces in the horizontal plane, at the point of contact, A, is given by: where ssv = solid-vapor interface energy sSL = solid-liquid interface energy sLV= liquid-vapor interface energy 6 = contact angle measured through the liquid phase. The angle and the surface tension, slv, can be measured accurately by the sessile drop method.3, The absolute value of the surface energy of the solid cannot be determined by this method, but with reasonable changes in the composition of the liquid only, the value of ssv can be considered constant. The changes in contact angle, then, can be attributed to changes in sSL and sLV and since sLV can be measured, the changes in sSL can be determined. Several studies have indicated that the surface and bulk properties of solid alloys can be correlated with electronic structure. The catalytic activity of copper-nickel alloys was reported to follow the dband vacancies in these alloys.5 Nickel has been considered to have 0.6 holes per atom in the d-band. The addition of copper to nickel is thought to bring about a filling of the d-band of nickel, since each copper atom contributes one electron. Thus, at an atomic concentration of 60 Cu-40 Ni (62 wt pct Cu-38 wt pct Ni) the d-band is believed to be full, and magnetic measurements support this view.6 If the electronic structure is influencing a property of the alloy, this property should show some sort of discontinuity as the composition changes from one side of the 60 Cu-40 Ni composition to the other. Since the catalytic activity can be considered as a surface property of the alloy, it is logical to assume that other surface properties, such as surface tension, may also be influenced by electronic structure. The suggestion has been made that there is a correlation between the solid titanium carbide-liquid Cu-Ni alloy interfacial energy and d-band filling.7 One purpose of this investigation was to determine if the changes taking place in the electronic structure with compositional changes in the solid copper-nickel alloys were reflected in the surface tension values of the liquid alloys. Such a change, if present, would lend support to the suggestion that one can refer to discrete energy bands in the liquid state. Other purposes of the present study were to investigate in detail the wettability in the system copper-nickel-titanium carbide, and to discuss the possible processes which take place during wetting in this system.

Jan 1, 1961

By A. B. Parsons

PUBLICATION of this little volume is a luxury that the Institute itself could scarcely afford. In truth, no engineer nor geologist, no assayer nor metallurgist would be likely to enhance his knowledge, improve his technique, or cut his own operating costs by reading this excellent translation of two booklets first published circa A.D. 1520. It is doubtful if the present enterprise would, in a practical or tangible way, "promote the arts and sciences connected with the economic production of the useful minerals and metals." And such, is the prescribed purpose for which the funds of the Institute should be spent. Fortunately for the Institute, the Seeley W. Mudd Memorial Fund is not so circumscribed; and the Fund Committee enjoys, greater liberty of action. The sponsorship by the Mudd Fund in 1942 of the publication of The Pirotechnia of Vannoccio Biringuccio, as translated by Dr. Smith and Mrs. Gnudi, was an innovation-indeed something of an experiment. Not only was the content of the volume significant mainly for its "cultural" and "scholarly" attributes; -but the format, an outstanding example of the fascinating art of bookmaking, bore no resemblance to the ordinary technical book. The Committee, frankly, was surprised at the enthusiastic reception accorded the volume. When a second edition was required, the Committee became convinced that the publication of material of this type, particularly if printed and bound in attractive form, was an appropriate avenue for utilizing a moderate proportion of the monies available from the Fund. The Bergbüchlein and the Probierbüchlein antedate by some years the first publication of De la Pirotechnia and of De re Metallica; but Georgius Agricola, the author of the latter work, made good use of the material in the earlier volumes. As pointed out in the Introduction, both

Jan 1, 1949

By Hsun Hu, R. S. Cline

The annealing behavior and the mechanism of re-orientation during recrystallization of iodide titanium cold-rolled 94 pct have been studied in detail. Results indicate that recrystallization occurs by the nucleation and growth of new grains, as in other common metals. Recrystallization nuclei form by the coalescence of subgraim, and the change in texture as a result of recrystallization is largely due to selective growth among the nuclei formed. The annealing of titanium is characterized by a wide range of overlap of the various stages of the annealing process, which may be responsible for a range of activation energies observed, and for the apparently gradual change in the annealing texture as a function of time or temperature. The deformation and recrystallization characteristics of titanium and zirconium are very similar. In cold-rolled strip, the deformation texture consists of two symmetrically oriented components, each having the basal plane laterally tilted at about 30 deg from the rolling plane and the [1010] direction parallel to the rolling direction. Upon annealing for recrystallization, the change in texture can be described, for simplicity,* as rotations around [0001].2'6'8 According to McGeary and Lustman,' recrystallization occurs in zirconium through normal growth of the subgrains, which they called "domains", without the nucleation of new grains; and the magnitude of rotation around the [0001] axis increases gradually during the progress of recrystallization. If these conclusions were true, the mechanism of recrystallization in zirconium would be basically different from that in most metals, since it is commonly known that recrystallization with reori-entation always involves the migration of high-angle boundaries. In an attempt to clarify the situation, the mechanism of reorientation during recrystallization in iodide titanium cold-rolled 94 pct was studied in detail. The structural and textural changes upon annealing at various temperatures were examined by optical and transmission-electron microscopy, X-ray pole figures, pole density distribution measurements, and micro-beam techniques. EXPERIMENTAL PROCEDURE Material and Specimen Preparation. An iodide titanium crystal bar was are-melted and solidified in a cold-hearth crucible under a purified argon atmosphere. The solidified ingot had dimensions of approximately 3 by 1/2 by 3 in. One face of the ingot was somewhat uneven, but was as clean and shiny as the remaining parts of the ingot. Large grains with a Widmanstatten internal structure were clearly shown on the shiny surfaces, indicating the occurrence of P — a transformation upon rapid cooling from the melt. Analysis of the are-melted ingot indicated C 0.033, N 0.010, H 0.013, 0 0.002 in weight percent, and traces of iron, copper, and silicon as detectable impurities. The ingot was cold-rolled -40 pct to 0.300 in. thick with a reduction of 0.005 in. per pass. The defects on the uneven side of the ingot were then removed by machining. This reduced the thickness to 0.285 in. The piece was then recrystallized by annealing at 800°C for 1 hr in a fused silica boat charged into a fused silica tube furnace under a vacuum of 10~5 mm Hg. To refine the grain size, the recrystallized metal was again cold-rolled 40 pct to 0.170 in., then annealed at 700°C for 1 hr. These treatments yielded a strip with a uniform equiaxed grain structure, having a penultimate average grain diameter of 0.04 mm and a hardness of approximately 90 Dph. Final rolling reduced the thickness from 0.170 to 0.010 in., corresponding to a reduction of 94 pct. The strip was rolled in both directions by reversing end for end between passes. Surface lubrication was provided by oil-soaked pads attached to both rolls. Specimens of 1 in. length (for X-ray examinations) and +in. length (for hardness and microstructure examinations) were cut from the rolled strip, and a width of & in. was cut from the edges of each specimen by a jeweler's saw. These specimens were then etched in a solution of 10 cu cm HN03, 5 cu cm HF, and 50 cu cm H,O to 0.008 in. thick to remove the surface metal, as well as the distorted metal at the saw cuts, prior to annealing or measurements. To minimize any surface reaction with the atmosphere, all specimens were kept in an evacuated desiccator. Isothermal Anneals. All annealing treatments were conducted in vacuum in a fused silica tube furnace as described earlier. The temperature of the furnace was controlled to within *2"C. The specimen was placed in a fused silica boat, then pushed into the hot zone of the furnace. It took about 5 to 6 min for the specimen to reach the furnace temperature. After the specimen was held at temperature for a desired length of time the boat was pulled to the cold zone of the furnace; the heating-up period was excluded from the isothermal annealing time. Thus, the uncertainty in annealing time is higher for very short anneals, but negligible for long anneals.

Jan 1, 1969

A new $18-million hydrometallurgical ore treatment facility for the recovery of molybdenum oxide was dedicated at Climax, Colo., on November 19 by Climax Molybdenum Co., division of AMAX. The Company has been producing molybdenum from molybdenite (MoS2) ores since 1918. Now oxide values, formerly lost in the sulfide flotation plant tailing are to be processed to yield about 3 million Ib per year of metal. In 1965, Climax produced about 50% of world molybdenum from sulfide ore. This ore is mined at the rate of 42,000 tpd. The annual production of concentrate is 100 million lb containing 90% to 92% MoS2, or about 50 million lb of metal. As only a relatively small portion of the total Climax production is sufficiently enriched in oxide molybdenum to process through the new plant, 5700 tpd of selected ore containing 1.5 lb of Mo per ton is now treated by the new process.

Jan 12, 1966

By David C. N. Cockburn

INTRODUCTION This paper analyses certain of the financial considerations which will commonly apply in relation to the following questions: - what equity structure or project vehicle should be adopted for the exploration and/or exploitation of a project by more than one unrelated participant? - what vehicle should be adopted by a participant for its participation in a multiparty project? Due to local, politically motivated laws in certain jurisdictions, or due to the overriding requirements of a dominant participant, there may be little choice of the underlying multiparty structure which may be adopted for the exploration, appraisal and/or development phases of a project. Nevertheless, even in such circumstances, attention should be given, at least in the preparation of the related documentation, or in considering methods of participating or funding the project, to certain of the points discussed below. This discussion of financial considerations in the context of the more commonly adopted multiparty structures concentrates primarily on fiscal, financial accounting, financing and funding aspects. TYPES OF PROJECT VEHICLE FOR MULTIPARTY INTERESTS The well known types of vehicle adopted for the participation in a project by more than one participant (assuming that the participants are effectively unrelated) are as follows. Joint Venture (unincorporated joint venture) By far the most commonly adopted structure for mining ventures, a joint venture is usually defined and documented in terms to distinguish it from a partnership for important tax and legal reasons. In essence, this is a contractual association of more than one participant to carry out a specific commercial project or purpose. The relationship between the separate participants and their respective rights, interests, obligations and liabilities are agreed between the participants in one or more contracts (viz Joint Venture Agreements or Joint Operating Agreements together with ancillary documentation). Unlike other project vehicles of participation, in most jurisdictions there is no specific body of law governing joint ventures. The participants thus enjoy contractual freedom to negotiate whatever deal they may wish between themselves. Jointly-Owned Project Company (corporate joint venture) A very familiar vehicle, this is a separate and distinct legal and tax entity incorporated under the company laws of the place of incorporation to undertake specific objects, and granted specific powers, in relation to the Project. Although certain rights, interests and obligations may be circumscribed in the governing corporate instruments by the promoter participants, the corporation laws of the relevant place of incorporation, and the selection of such governing laws (assuming freedom of choice) and future political changes in such corporate laws, should be carefully considered. The use of a company in a multiparty structure may be peripheral to the project itself as a specific purpose vehicle (for example, a joint sales agent or marketing company or a joint borrowing vehicle) or it may form a central function such as in the case of a tolling company which will own the project for legal and taxation purposes and raise financing with the backing of the shareholder participants commonly by the adoption of take-off, throughput and/or user agreements. Partnership This is a legal relationship, subject to the often wide-sweeping restrictions of the relevant local partnership laws, under which the participants have agreed to carry on a business venture together with a view to profit. The effect of the relevant partnership laws, as well as the various types of partnerships and the

Jan 1, 1985

PRESIDENT E DEGOLYER, District 0 NEW YORK, N Y PAST PRESIDENTS J V. W. REYNDERS, District 0 NEW YORK, N Y SAMUEL A TAYLOR, District 3 PITTSBURGH, PA FIRST VICE-PRESIDENT GEORGE OTIS SMITH, District 4 WASHINGTON, D C TREASURER CHARLES F. RAND NEW YORK, N Y SECRETARY H. FOSTER BAIN NEW YORK, N Y

Jan 1, 1923

By Corliss R. Kinney

SINCE the first atomic bomb exploded over Japan, a great deal of speculation has been published about the use of atomic energy instead of coal for the production of power. Atomic energy, in time, may displace coal for this purpose, but atomic energy will not displace coal in supplying chemical raw materials to the rapidly expanding carbon-chemicals market. Modern civilization demands large quantities of carbon compounds and the logical source of many of these is coal. Consequently, many progressive operators are considering the possibilities of the utilization of coal as a chemical raw material as never before. Furthermore, the demand for clean, smokeless, and ashless fuels will continue to increase and the only way to handle coal under those conditions is to take it apart, just as crude petroleum is taken apart. One can readily imagine where the petroleum industry would be now if it had insisted on selling customers only crude oil, perhaps emulsified with a little salt water to correspond to the moisture and mineral matter in raw coal. The time seems to be coming at an accelerated pace when mine operators will find that competing for a highly selective fuel market by producing a larger tonnage at smaller cost will be less profitable than to increase the value of a smaller tonnage many fold by producing something more valuable to industry and civilization than raw coal. For example, about 750,000 tons of carbon black selling for $50 to $60 per ton was produced in the United States in 1945. This tonnage is insignificant compared with the total production of coal in the United States, but a very tidy tonnage, together with the coal necessary to operate the process, for any mine operator fortunate enough to obtain a method of producing a better carbon black from coal. From the point of view of tonnage, the manufacture of coke of various kinds and its by-products is at present the most important source of carbon chemicals from coal. Nearly 20 per cent of the coal mined in this country is used for this purpose. A large proportion of the coke is used for the production of iron and steel, but even in this operation a considerable part of the coke is used for a chemical purpose; that is, the reduction of the ore to metallic iron. In addition, large quantities of coke are used in manufacturing many important products that find their way into the market. POSSIBILITIES OF ACETYLENE One of the important chemicals manufactured from coke is calcium carbide, from which many products are made. One of these is acetylene. This hydrocarbon can also be manufactured from natural gas or from waste oil-refinery gas and' these industries will probably offer competition for the manufacture of acetylene. Coke-oven gas can be used for making acetylene and should receive consideration

Jan 1, 1946

By E. Mcl. Tittmann

Deep-seated human instincts urge us to positively mark the passage of time. We celebrate the passage of each year. Years give way to decades, and decades to half centuries and centuries. At all these mileposts we are inclined to pause, take a look around and catch our breaths before embarking on the next leg. We are at such a point now and this meeting I am sure will give direction to the road ahead into the decade of the seventies. In looking around at this point, 1973, it is obvious to all of us that the environment in which we must mine, mill, smelt and refine lead and zinc has radically changed. These changes have, of course, occurred over a long period of time. They have, however, all been in the same general direction. They have all had the same motivation. The period of greatest contrast is probably the fifteen years just before World War II and the fifteen years following the end of that war. I thought that I might review briefly with you what seems to me to be four of the more important changes that have developed since World War II that profoundly affect our activities in the lead and zinc industry. I mentioned before that all these changes have been in the same direction; that is, they have all tended to restrict our freedom of action in pursuing our objective of producing lead and zinc on a competitive basis at a profit. Consequently, in discus- sing them you may think that I am merely viewing with alarm. This is not the intent. This is merely supposed to be an objective analysis. I think it appropriate before discussing these trends in de- tail to examine the position of lead and zinc today.

Jan 1, 1970

By Robert H. Richards

If one holds up a prism, or wedge of glass, with narrow angle, say l° to 2O, and compares the transmitted image with the image seen above or below the prism, the former will be found to be thrown to one side by an amount varying with the angle of the wedge. Speaking of the two rays as the direct ray and the bent ray, we may say, that when the bisecting plane of the prism is at right angles to the line of sight, the angle between the direct ray and the bent ray will be constant for any given prism. If now we place a prism or wedge of glass in such a position that it half-covers the objective of a telescope, we shall obtain on looking through it two images of every object seen—one image by the direct ray, which comes through the unaovered half of the objective, the other which comes through the prism, and is the image by the bent ray. The angle of divergence of these two raps will be constant and unalterable, whether the telescope is directed to a near object, with its eye-piece at increased distance from its objective, or upon a ' distant object, with eye-piece nearer to the objective. That is to say, if the " throw " or apparent dislocation of the image is one foot in one hundred feet it will be two feet in two hundred, ten feet in a thousand, and so on. The usual form of stadia-telescope has at the focal point of the objective two spider-lines, placed at a definite distance apart and intended, let us say, to represent a throw of one foot in one hundred feet. But as the distance between lines remains the same, while the distance from the objective to the webs diflers with every variation in the distance of observed objects, it follows that the angle between the lines of sight which these two spider-lines define cannot be con stant, but must vary with every increase or decrease of distance be tween the instrument and the object viewed. If in Fig. 1 we represent three positions of the spider-lines by W1, W2, W3, and three objects corresponding to those positions by 01, O2, 0, at near, medium and distant positions, we see at

Jan 1, 1892

By R. R. Seeber

In the copper-mining district of northern Michigan a fair-sized mine usually operates two or more shafts along the strike of the lode, these shafts being usually at least 1,000 ft. apart. The tonnage to be hoisted from each shaft is large—from 13,000 to 25,000 tons per month. The hoisting-engines used are generally steam-driven, non-condensing, duplex engines with Corliss valves, supplied by steam from separate boiler-plants where the distance between shafts is great. In an attempt to centralize power-plants and secure central-station economies, the Winona Copper Co. installed an electric hoist of the Ilgner type, with Ward Leonard control. A brief description of this plant has already been published.' The only point of variation from the simple Ilgner set lies in the connection of two generators to a single induction-motor by flexible couplings. These generators serve motors which operate hoisting ing-drums at separate shafts, viz., No. 4 shaft, Winona, and No. 1 shaft, King Philip. The hoist for No. 4 shaft is about 1,700 ft. from the power-plant, arid in this building the motor-generator set is placed. No. 1 King Philip hoist is 1,500 ft. from the motor-generator set. The equipment of the motor-geaerator set is as follows: In the middle of the set is a 12-pole, 450-h-p., 600-rev. per min., 2,080-volt, three-phase, 60-cycle, variable-speed induction-motor, connected on each side to a 20-ton fly-wheel which is 10 ft. in diameter, and to a 6-pole, 170-km, 575-volt, interpole, direct-current generator. On each side of the shaft is placed a separate exciter, which delivers current at 125 volts. The lubrication of the four main bearings that support the fly-wheels

Jan 1, 1911

The Institute maintains a dual relationship with students: (1) an individual relationship with a Student Associate; and (2) a relationship with local organizations of students, known as Affiliated Student Societies or Student Chapters. 1. The conditions of Student Associateship are set forth in Section 8, .Article 1 of the By-laws of the Institute (see p. 45 and following pages) During 1934, sundry amendments were made for the purpose of improving the student relationship. Post-graduate students are now eligible; and the associateship can be maintained, with the payment of the regular dues of $2 per gear, for 18 months following graduation in June. A Student Associate is given a subscription to MINING A ND METALLURGY: he is accorded the privilege of getting special publications such as "The Porphyry Coppers" and "Ore Deposits of the Western States" at the reduced prices applicable to Members; he has the privileges of the Engineering Societies Employment Service and the Engineering Societies Library; and he is not only invited but urged to attend all meetings of the Institute, its Divisions and its Local Sections. The Institute wants to extend the hand of professional fellowship to students following mineral industries curricula.

Jan 1, 1936