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By C. M. Signer, W. P. Hewitt

THIS is a story of a mine discovered in the days of the Conquistadores but that remained unimportant until the second decade of this century. Without the usual legendary history of romance and fabulous riches it has become famous for the development of unexpected metals and unusual problems. These developments and experiences, exciting and interesting as any legend, are the substance of the San Antonio mine of the Santa Eulalia district in northern Mexico. Originally opened for its silver-lead content, it developed a tin deposit of singular economic importance and unique geologic interest, a vanadium orebody that for a few years placed it among the leading vanadium producers of the world, and now lead and zinc sulphide ores. It has been the seem of a disastrous flood that brought deep-sea divers into Mexico's desert mountains and raised important problems regarding ground water, demanding unusual measures. Geology and operating questions relating to the above matters will be discussed and much of it is recent history which has become a part of Mexican mining lore. History Dates Back to 1325 Santa Eulalia is the oldest of American cities, founded in 1325 by the Aztecs under the name of Tenochtitlan and devastated in 1521 by Cortes and his rapacious band of iron-willed adventurers. Their lust for gold burned through the Aztec empire and onward into most of North America. Santa Eulalia was in the path of conquest. In 1591 the district's first ore discovery was made near what is now the San Antonio mine. The ores carried no gold and the silver-lead content was unattractive to the early pioneers. Not until 1700 was real mining activity undertaken.

Jan 1, 1952

By John Garcia

IN some districts of the bituminous coal field the problem of construct-ing bulkheads to seal off water under pressure is becoming increasingly important. Recently this matter has been brought very much to the front by the loss of a large Illinois mine due to failure of a bulkhead that separated it from several old, flooded mines. As this great misfortune has provoked much inquiry about proper bulkhead design, it-is felt that a description, of the successful and extensive water-sealing practice at three mines that have different natural conditions will be of considerable interest to those connected with properties having a present or future water problem and to engineers that may have to design safe bulkheads of economical construction. These three mines are the Saxton and Dresser, near Terre Haute, Ind., and the Hegeler, near Danville, Ill. All three have water conditions that make it necessary to regularly seal off all worked-out sections of the mine, and there are considerably over a hundred bulkheads in each. As far as the writers know, these three mines are the only ones in the bitu-minous coal fields of the United States with anything like so large number of water seals and experience, although a number of other mines are known to have a few bulkheads. More detail will be included herein on the Saxton mine than on the others, as the writers are more familiar with it.

Jan 1, 1937

By John Fritz

Gentlemen of the American Institute of Mining Engineers : I desire to thank you sincerely for the distinguished honor you have conferred upon me by electing me to the presidency of this society, a position which in the past has been filled by some of our most distinguished and ablest members, men eminently qualified by education, practical training and a business ability which has enabled them not only to fill the position with credit to themselves, but as well with honor to the society. In deference to a custom long established, by which the presidentelect is expected to read a paper on some subject with which he is more or less familiar, I have thought that a brief review of the methods employed in the manufacture of iron, as witnessed by myself, and reaching back to 1838, would interest some of our older members and give our younger ones a glimpse into the trials and difficulties encountered in those early days by the pioneers in this great industry. In 1840, 12 to 20 tons of pig-iron was the make of a furnace per week—at this time from 1200 to 2000 gross tons. In 1840, 3 to 4 tons No. 4 wire rods per turn. They have lately made 176 gross tons in 11 hours. In 1840 I have not the quantity of puddled iron made; but it was

Jan 1, 1895

By L. M. Barker

THE New Cornelia Branch of the Phelps Dodge Corporation is at Ajo, Pima County, Ariz. It is at the southern terminus of the Tucson, Cornelia and Gila Bend Railroad, which connects with the Southern Pacific Railroad at Gila Bend, Ariz., approximately 43 miles to the north. HISTORY Early history of the Ajo district has been related by A. W. Allen1 and by T. A. Rickard.2 Briefly, steps looking to the large-scale development of the ore body were instituted as early as 1912. This work culminated in the equipment of the property for open-pit mining by steam shovels. Ores initially mined carried economic amounts of copper carbonates as the principal copper-bearing mineral. Treatment methods developed for the extraction of the copper content involved leaching and a 5000-ton leaching plant was constructed and placed in operation in early 1917. Description of methods and equipment employed in this plant has been given by A. A. Tobelmann and James A. Potter.3 As exhaustion of the carbonate ore body neared, and mining oper-ations exposed an adequate tonnage of sulphide ores, a 5000-ton con-centrator was constructed for their treatment. That plant has been described by H. Kenyon Burch.4 Construction was completed and the plant was placed in operation in early 1924. Changes made in the original plant to improve practices and increase production will be the subject of subsequent paragraphs of this paper.

Jan 1, 1939

By R. A. Pasternak, B. Evans

A dynamic technique for the determination of solubilities of gases in metals has been explored, using the N-Nb system as a test case. An initially clean sample, maintained at constant high temperature, is exposed to the gas at low pressure: the rate of sorp-tion and the corresponding change in sample resistance are measured continuously. A pronounced decrease in the slope of the resistance concentration curve is observed at the terminal solubility. The rate of gas uptake by the sample was determined in an ultrahigh-vacuum flow system equipped with a servo-control which maintains constant pressure in the sample chamber; the system and the technique have been described in detail elsewhere. 1,2 The sample was held at constant temperature during sorption by maintaining approximately constant power input into it; this results in constant temperature, since the emissivity of a metal is independent of moderate concentrations of dissolved gas. The simple electrical circuit used both for heating and for resistance measurement is shown in Fig. 1. The power input into the filament is where R is the filament resistance, RL is an adjustable resistance in series with the filament, and VT is the constant dc potential of the power source. If RL is set equal to R at the beginning of an absorption run, the power input becomes insensitive to subsequent resistance changes; for example, an increase of 20 pct in sample resistance is accompanied by a decrease in power input of less than 0.8 pct; i.e., the

Jan 1, 1967

By E. O. Wagner, V. F. Parry, W. S. Landers

Following investigations by the Denver Bureau of Mines on drying fine coal in the entrained state, Texas Power & Light Co. employed the fluidized technique to upgrade Texas lignite for use in power plants. Because of the rapidly rising cost of natural gas in Texas the company agreed to cooperate with the Bureau of Mines in studying further the upgrading of lignite by low-temperature carbonization, since potential value of the tar would help off- set the cost of fuel. Considerable interest was aroused, therefore, when Aluminum Co. of America decided to use dried lignite in its 240,000-kw power plant at Rockdale, Texas, operated by Texas Power & Light. Carbonization of coal before burning in a power plant is not new. Plants in Germany have been operated for many years on carbonized brown coal and lignite briquets produced in large integrated plants. Large-scale experiments in carbonizing pulverized coal with hot flue gases were made 30 years ago at Milwaukee, and many inventors have proposed other processes. In the U. S., technical and economic problems have prevented successful operation of large plants on carbonized coal, but new techniques of handling solids in fluidized beds may overcome these difficulties, particularly if the higher volatile noncoking coals are used.

Jan 1, 1956

Uranium was the prima donna of 1978, and the exploration pace was fast and furious in traditional uranium producing areas such as the Powder River Basin, Grants mineral belt, San Juan Basin, and Uravan mineral belt. Adding fuel to the fire were several significant discoveries: The Date Creek Basin of western Arizona, the McDermitt caldera of northern Nevada, and Tallahassee Creek in Colorado's intermontane basin. Advances in solution mining haw resulted in deeper drilling on the Texas Coastal Plain, and the price of uranium has encouraged widespread exploration in frontier areas and non-sandstone environments.

Jan 5, 1979

Jan 1, 1886

By R. P. Ehrlich, D. A. Dahlstrom

In the hydrometallurgical circuit, many phase separation steps are usually necessary. Typical steps are pregnant liquor - leach residue separation by counter- current decantation or continuous vacuum filtration, clarification of liquids prior to precipitation, ion exchange or solvent extraction, dewatering of final product, etc. The paper discusses the more recent advances in these areas and considers general operating parameters and cost factors. In addition, emphasis is placed on future needs because of the growing importance and necessity of hydrometallurgical processing of minerals.

Jan 1, 1973

By W. H. Emmons

A DIATREME is a hole blown through a rock by gases, presumably of volcanic origin. Not all pipes of ore have formed by deposition of metals in such openings, but a con-siderable number have so formed. In this paper are described peculiar vein patterns that are believed to be incipient diatremes or "perforation pipes." Grading into this group is one showing thorough brecciation without rotation of fragments and into the latter a group of ore pipes showing brecciation with rotation of fragments-many of them with well rounded fragments. Also, volcanic craters or volcanic necks are explosion pipes. These may carry ore deposits along their contacts and some carry deposits within the pipes. As new data appear this group becomes increasingly impressive. It has been shown that veins are concentrated in and about cupolas of batholiths and that such veins commonly lienearly parallel to the long axes of cupolas as these are shown on plans. It would be supposed that conical cupolas would have radial patterns, but few vein systems exhibit radial patterns. It is probable that explo-sion pipes also may form in areas above conical cupolas. From these the gases escape more violently because the loads above them are less than above an elongated cupola where larger bodies of rock are affected. The hypothesis is sound mechanically, for the top of an elongated cupola is a line whereas the top of a conical cupola is a point.

Jan 1, 1938

By George Gardner

THE application of wet cleaning processes for the beneficiation of bituminous coal has created in some localities a problem in the recovery and disposal of fine solids in the washery water. The maximum allowable concentration of these solids in the washery circuit that is consistent with satisfactory operation of the cleaning units remains a controversial point. It has, however, been generally recognized for a number of years that some degree of control should be exerted over the concentration of such material. Early methods of control involved intermittent or continuous dis-charge of a portion of the plant slurry into near-by streams or settling ponds, and this persisted even after the adoption of settling tanks or cones. The practice is not always economical, for two reasons: first, because of the waste of coal, and, second, because it is sometimes difficult and expensive to obtain an adequate supply of water. The latter condi-tion often is aggravated by chemical treatment of the make-up water that is necessary to prevent excessive corrosion of plant equipment. The modern approach to this problem has been the adoption of continuous thickening devices. However, because such equipment occupies consid-erable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, there-fore often the performance of such units is not altogether satisfactory. In recent years, European washeries have increased the rate of settling of the fine coal from the slurry by the addition of specially pre-pared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation.

Jan 1, 1939

By C. L. Horn

All the tunneling machines discussed in this chapter are Calweld machines. I have divided the machines designed for soft-to-medium formations into three groups, correlated with typical formations and estimated compressive strengths: 1) Running sand and silt requiring blade cutters. 2) Chalk and clay, requiring drag-type cutters, for compressive strengths ranging from 0 to 2000 psi. 3) Sandstones, hard clays, and limestones, requiring disk cutters, for compressive strengths ranging from 2000 to 20,000 psi. All of the soft-to-medium-formation machines are powered by electric hydraulic or diesel hydraulic pumps. The pumps in turn drive hydraulic motors for the torque reaction. The soft-to-medium-formation machines are enclosed in a 360º shield with a cutting shoe, a center portion of the shield housing the mechanical equipment, and a tail shield. Tunnel supports are usually required, and the supports are normally erected in the tail shield. Our first machine was built in 1963, and all but five of the machines illustrated in the figures with this chapter were built in 1966 and 1967. Some of the machines manufactured will be discussed in the following sections; specific features as development has progressed will be pointed out. HARD-ROCK MACHINE The Calweld hard-rock machine has been designed along basic and accepted principles for a hard-rock mechanical borer. The features of this machine are as follows: 1) Direct electric motor drive through a planetary gear reduction ring and pinion gear, and then to the cutting head through a hollow drive shaft.

Jan 1, 1970

By Donald W. Barnett

U.S. environmentalists have tended to oppose all new energy developments. Their efforts may be counterproductive because opposition to, say, offshore oil directly leads to the continued use of other energy sources that may have a higher social cost. Rather than attempting to eliminate all pollution from energy production, which would be prohibitively expensive, one should minimize the social cost of energy production for the given demand. Linear programming is used to rank various oils (California State and O.C.S., Gulf of Alaska, Prudhoe Bay, Athabasca tar sands, oil shale and certain foreign crudes) in terms of their social desirability. The objective is to minimize the cost of supplying the California market, subject to resource, sulphur and oil spill constraints. Social desirability is indicated by the inclusion of the oil in the optimal solution and the size of the associated shadow price. the larger the shadow price, the greater the benefits of increased production. The more negative, the greater the cost associated with forcing consumption of that fuel. The environmental shadow prices indicate the size of the trade-off between a particular environmental standard and minimum cost. The trade-offs can be surprisingly large. any reasonable spill standard can be achieved by changing the development pattern. Generally, the further offshore, the smaller is the environmental degradation, but the more expensive is the oil. Foreign oils can be economically and environmentally inferior to domestic oils. Crude from the California O.C.S., San Joaquin Valley end Prudhoe Bay appears a valuable resource, while the Gulf of Alaska, synthetic and foreign crudes appear marginal to submarginal.

Jan 1, 1977

By H. W. Kropholler, L. A. Cramer, E. T. Woodburn, J. C. A. Greene

A generalized mathematical structure is proposed whereby internal species mass flows within a flotation network are defined uniquely by a matrix of enhancement factors. An element of the enhancement factor matrix is defined as the ratio of the mass flow of that species leaving a given cell in the concentrate to the species mass flow leaving the same cell in the tailings. To predict the enhancement factors, knowledge of flotation kinetics effects is required. Recently experimental data has become available relating to the performance of industrial flotation circuits which indicate that the discrete or discrete-distributed kinetic schemes are capable of reasonably effective simulations. These simulations show the importance of including froth effects. The prediction of performance of networks from small-scale batch tests on flotation streams shows that the model for the froth phase used in the simulations does not scale-up well and that aeration effects are also difficult to predict. The network analysis should be useful in differential flotation of complex ores and it is disappointing-in this context that little information on the kinetics of activation and depression is available.

Jan 1, 1976

By S. M. Moos, R. E. Dugger

In reviewing available vacuum filtration equipment in this paper, several types of filters have been included which are probably not familiar to operators in the mining industry. However, it was felt that these units might be of interest in the event that an application should arise for the filtration of a product in the future that does not exist today. In addition, exposure of our industry to equipment used in other industries might have a tendency to be thought provoking and perhaps lead to the development of equipment and/or applications in our industry which do not necessarily exist at this time. Most innovations in filtration equipment have been confined to the improvement or design change of components and accessories, particularly reflecting the availability of materials of construction that have been developed. Recent developments in the application of horizontal belt filters have been innovative. The application of this unit as a substitute for or an adjunct to thickeners in a CCD circuit can certainly be innovative and perhaps provide a basis for reduction in capital and operating costs in this area. For example, mill tails are generally pumped at the highest possible density that will adequately flow. Tailings ponds and dams with their attendant design requirements are based upon this estimated water volume.

Jan 10, 1979

THE record of the development of physical metallurgy since the founding of this Institute embraces by far the greater part of physical metallurgy as this subject is recognized today. Yet it is not to be supposed that the metallurgist interested in the properties and behavior of solid metals at the beginning of this period was without important and even fundamental information. He had an empirical knowledge of the behavior of solid metals which extended backward into prehistoric times and he had the early beginnings of many of the chapters in the science of metals. Industry was burgeoning in many directions, for methods had been developed, especially in the manufacture of steel that provided materials in extremely large tonnages, permitting applications of metallic materials on a very widespread scale. These multitudinous new uses of metals created an increased interest in the behavior of metals, and provided the basis for the rapid development of a science of metals. Indeed, the development of science generally that accompanied the industrial revolution reached a flood tide toward the end of the century, furnishing the metallurgist basic principles in chemistry, physics, mechanics, and crystallography that would shortly be extensively applied to metallic behavior. In this account, the early developments in the wide metallurgical field will be traced, in order that the status of physical metallurgy in 1871, when this Institute was founded, may be clearly seen. The subject of metallurgy in antiquity has been written upon frequently and at length. We shall here no more than indicate the main features that we need to define the position in 1871 and to provide a proper background for discussing subsequent developments. The writings of Pliny,1 23-79 A.D., to which Robex-ts-Austen3 fre-

Jan 1, 1948

By C. R. Kuzell, G. H. Wigton

Knowledge of the thermal capacity of gases is of great importance in making metallurgical calculations. The metallurgist is frequeqtly called upon to investigate and determine furnace efficiencies in which the heat carried into or out of the furnace by gases is a large item in the heat balance. Not only do such problems present themselves in the determination of furnace efficiency, but also in the study of the application of heat in accessory apparatus, such as stoves, regenerators, waste-heat boilers, driers, etc. The thermal effect of the use of excess air in the combustion of fuel, the theoretical temperatures of combustion, the quantity of heat in hot blast at various temperatures, the effect of hot blast on furnace temperatures, are a few more examples of frequently occurring calorific problems involving gases. So many are the applications of the data on the heat capacity of gases that the subject merits careful study. The heat in a gas maybe due to its heat of combustion, if it is a combustible gas, and to its temperature. The latter is called its sensible heat and is the heat absorbed or evolved by a gas as its temperature is raised or lowered. The heat of combustion of gases is well established and is commonly known. The values can be found in almost any modern treatise on metallurgy. The sensible heat of gases has not been so well established because it is in most cases a function of the temperature, and the values of specific heats of gases over a wide range of temperatures have only recently been determined. It is the purpose of this paper to deal with the sensible heat of gases. - The calculation of sensible-heat capacities1 from specific-heat equations is a comparatively long and tedious operation. This is especially

Jan 1, 1915

By J. J. Knoerzer

A full-scale operational test was conducted on the Coaltek preheating and pipeline charging system at the Semet-Solvay Div. of Allied Chemical at Ironton, Ohio, for the purpose of determining whether a high-quality blast furnace coke could be made from blends containing at least 75% Illinois No. 6 Coal and at the same time reduce air pollution during the charging of the ovens. The coke produced had similar physical characteristics as compared to our conventional wet-charged coke, with the exception of smaller size for the preheat coke. Air pollution during charging was con- trolled and there were no serious operating problems. The coking time was reduced 25% from our normal 17 hr for wet charging to 12.8 hr for preheated charges. The blast furnace performance with preheat coke was satisfactory.

Jan 1, 1976

By J. N. Hummel

THE methods of electrical prospecting, which employ contact electrodes to produce an electric field in the ground, furnish information concerning the constitution of the material beneath the surface, as indicated by the distortion of this artificially produced field and anomalies therein. To reveal the distortion of such field of known character, it is only necessary to measure qualitatively the direction of the field, using sensitive compensation methods. In such a case, the survey is relatively simple, and that is an important factor from a practical point of view, The distortion of the normal field thus determined permits an easy interpretation and gives approximate information as to the subsurface conditions, without the necessity of a thorough theoretical knowledge of the electrical field. The true field of application of the equipotential lines and search-coil methods, which are based on this principle of directional determination of the electrical field in the ground, is that of search for deposits of economic minerals for the mining industry, although they can also be used in solution of other problems; for example, in the determination of the strike of anisotropic beds. The distortion of the electric field as represented by the picture of equipotential lines or other measured curves is striking only when bodies having conductivities different from that of the country rock are embedded in the underground, or when the underground is anisotropic.

Jan 1, 1931

IN NOVEMBER 1933 I had the pleasure of receiving an autographed copy of a small brochure entitled "Birth of the Porphyry Coppers." The author, James Colquhoun, a distinguished British mining engineer, had been the dominant figure in the Arizona Copper Company, Limited, which, until its acquisition by the Phelps Dodge Corporation in 1921, had been the principal producer of copper in the Morenci district. In addition to the highly productive Humboldt and Longfellow mines it owned the Clay property, which, of course, has now become Arizona's No. 1 copper mine. Except for Utah Copper it is the premier Porphyry copper enterprise in the United States. Mr. Colquhoun's little volume was inspired by THE PORPHYRY COPPERS which had appeared early that year. In a most courteous and friendly way he adduces data to show that "we (Arizona Copper Company Limited) were successfully treating low-grade porphyry ores in quantity for at least four years (1901 to 19W) before the Utah Copper Company did anything at all." This last remark is based on the figures in THE PORPHYRY COPPERS showing that Utah's first production came from the Copperton pilot plant in 1905. Mr. Colquhoun traces the story of Morenci beginning in 1883 when he first arrived there. He tells how the rich self-fluxing ores (containing lime- stone, silica, and iron in proportion to permit direct smelting to produce black copper) were gradually exhausted. High-grade siliceous ore could be mixed in limited quantity with the self-fluxing ores; and oxidized ores were leached to contribute substantially to the production of the district. But

Jan 1, 1957