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By N. J. King, R. F. Hadley

Alluvial valley floors constitute a valuable land resource and are important to ranching operations in the semiarid western United States. This resource may be in jeopardy locally if the alluvial deposits are disturbed by surface mining of coal deposits. Erosion problems caused by poor land-use practices can cause trenching of the unconsolidated alluvium with a consequent lowering of the water table and depletion of soil moisture needed to support vegetation. Historical evidence of this sequence of events is abundant in the geologic literature and serves as the basis for assessing potential impacts of surface mining. The potential geomorphic impacts of surface mining on alluvial valley floors with regard to fluvial processes are. (1) disruption of the longitudinal profile followed by valley trenching and high sediment yields downstream, and (2) replacement of the excavated alluvium with unconsolidated material that does not have similar physical characteristics and may be susceptible to erosion. Mining may disrupt the existing hydrologic framework affecting stream flow, ground-water levels, and water quality of both surface and ground water. Although functional hydrologic and geomorphic processes are similar, each valley represents a complex environment that does not submit to broad generalizations.

Jan 1, 1981

By T. M. Gurr

The United States is the world's leading producer of phosphate rock. In 1975 according to the US Bureau of Mines' statistics, 44.3 million tonnes (48.8 million st) of phosphate rock were produced in the United States, l which is 40.6% of the world's production.2 The major phosphate producing areas of the United States are located in [Fig. 1] and the production for 1975 is listed as follows: [ ] All of these areas produce phosphate from deposits which are of marine sedimentary origin. Occurrences of phosphate exist throughout the United States in numerous locations that are of both igneous and sedimentary origins. However, these other phosphate occurrences vary greatly in extent and economic significance. Georgia, South Carolina, California, Texas, Arkansas, Kansas, Iowa, Alabama, Kentucky, and Virginia are but a few of the states in which phosphate is thought or known to exist. The near future expansion will probably continue to be in, or near, existing producing areas, (i.e., Florida and North Carolina).

Jan 1, 1980

By Robert R. French

Beneficiation of low-grade nonmetalliferous mineral deposits by electronic color sorting is currently undergoing a period of rapid development. For those deposits in which the specific gravity, strength, soundness, and electric and magnetic properties of the ore and gangue are similar, the possibility of separation by color, reflectivity, or fluorescence offers hope for the utilization of much poorer quality ore than previously thought possible. For those ores in which consistency of color is required or for which a dry process is preferred, the electronic color sorter is particularly adaptable. Tests performed late in 1966 and reported herein are the result of continued interest in the dry beneficiation of gypsum and the development of higher capacity color-sorting machines. These tests should be considered only as an indication of the efficiency of the process and only with respect to the low-grade, untreated ore tested. Although most of the ore mined in Martin County, Ind., is of acceptable quality, a few thin carbonate strata and irregular nodules of dolomite and limestone are present within the main evaporite bed (Fig. 1).

Jan 1, 1969

By Glenn Allen

SAN FRANCISCO Mines of Mexico, Ltd. owns and operates an extensive group of claims in the San Francisco del Oro-Santa Barbara district, about 15 miles southwest of Parral, Chihuahua. The property comprises the mines, aerial tramways, flotation mill, power plant, shops, offices, assay and testing laboratories, modern hospital, water and sanitary system, quarters for miners, mechanics and operators, a well housed colony for Mexican staff employees and residences for foreigners. Each colony has a club house and mess and tennis courts. The employees have constructed a nine-hole golf course. In other words, the property is self-contained and completely integrated for production of lead and zinc concentrates from complex sulfide ores.

Jan 1, 1930

Jan 1, 1887

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Jan 1, 1938

By L. C. Weiner

THIS study was undertaken to round out an investigation on the effects of solid environments on the brittle fracture of zinc single crystals.' In the previous work it was demonstrated that the presence of a surface film increased the cleavage strength of crystals whose basal planes were oriented almost parallel to the tensile axis by some 43 pct. This increase was observed to be independent of the type of surface-coating material, as well as of thickness of film above a certain small critical value (about 200 to 300A). These observations were described sat- isfactorily by a dislocation-pile-up-at-a-barrier model of brittle fracture2 in which twins modifying the dislocation path act as barriers, their increase in number and homogeneity of distribution brought about by the presence of the surface film. From previous work reported on the strength of ductile metal crystals as affected by gaseous and liquid environments,3 it may be concluded that the effects of these media are present only when the environment produces a surface film on the initially clean-surfaced crystal, or when it has a disintegrating effect on a previously existing surface layer. Similarly, it might be expected that an increase in cleavage strength of initially clean zinc crystals (xo = 3", A, - 28") will result only when the gas or liquid reacts with the crystal to produce a solid, adherent surface film. Clean-surfaced crystals,l 2 1/12 in. in length, were tested in tension at room temperature in an Instron

Jan 1, 1959

By Donald E. Crowell

In the fall of 1969, ASARCO and Newmont Mining Co. began the design of the 700tpd concentrator at their Black Cloud shaft located near Leadville, Colo. The concentractor would treat by flotation a Pb-Zn-Ag ore containing minor gold values. Flowsheet design was based on laboratory test work performed at the Minerals Research Testing Laboratory of ASARCO. Since the concentrator is located at an elevation of 11,000 ft, cold weather was a major factor in design considerations. The original capacity was designed as 700 tpd but for various reasons an ultimate capacity of 1,000 tpd was desired. This necessitated special consideration in the design of several areas, particularly the grinding circuit. The grinding circuit chosen was a single 9 X 12 ball mill operating in closed circuit with one 20-in. cyclone. The ball mill will operate at low speed and as an overflow type originally. The mill can be speeded up and converted to grate type for handling the larger tonnage when required. Thickeners and filters were oversized and space was left for additional flotation cells in order to handle the increased tonnage in these areas. Pumps were sized so that they could handle the increased tonnage by increasing their speed. Construction began in May 1970; the Black Cloud concentrator went on-stream in April 1791.

Jan 1, 1974

By C. A. Edwards

Jan 1, 1935

By H. M. Chance

The great outspread of the coal measures over portions of thirtyone of the sixty-seven counties of Pennsylvania, and the large number of workable seamy comprising the coal series,—together with some workable seams lately shown to belong to the (so-called) barren measures,—-create the impression that these fields contain a practically inexhaustible supply of fucl, and those who have estimated or attempted to estimate their available tonnage have generally promulgated this view. But the actual total contents of this coal-field is of no importance to us at present; calculations including all seams, whether thick enough to mine or not, whether pure enough to furnish a marketable fuel or not, whether accessible at reasonable depth or not, are of no practical value. As coal producers, we are interested not in the total contents, but in the total amount of easily accessible coal of good quality contained in beds thick enough for remunerative mining. The estimates contained in this payer refer exclusively to workable and accessible coal of commercial value,—we may call it available" coal. I am not aware that any one has as yet attempted to estimate in

Jan 1, 1882

By Joseph Ames

THERE are two distinct questions associated with the concept of temperature: one is practical, the other is theoretical. Our fundamental ideas of temperature come from our senses; we know what we mean by the words "hot" and "cold," or by saying one body is "hotter than another." But for scientific purposes words require definition. We are guided in this matter, as in all other scientific questions, by our knowledge of facts of observation. When two bodies at different temperatures are intimately associated, e.g., a hot stone is, dropped into a pail of water, our experience is that ultimately they come to the smile temperature as far as our senses can tell; the hot body becomes colder and the cold body hotter. In the case of a block of ice, immersed in, water, the ice melts, forming cold water, which then mixes with the other water, the final result being water colder than the original water. From our knowledge of the nature of heat phenomena, we learn that in this process one body loses, heat and the other gains heat, the condition of equilibrium being, one in which each body gains Is much heat as it loses. It is distinctly assumed in this statement that only two bodies are concerned in the transfer of heat, all other bodies being rendered in some way impervious to heat. The body that in the process loses heat is said to have the ?higher temperature" while the body that gains the heat is said to have the "lower temperature;" and, when thermal equilibrium is reached, the two bodies are said to have the "same temperature." Consequently, the temperature of a body may be defined, is it was by Maxwell, as "its thermal state considered with reference to its power of communicating heat to other bodies."

Jan 9, 1919

By Harrison R. Cooper

The key to concentrator automation is practical means for obtaining continuous assay data from concentrator streams. The technique most successfully used is x-ray fluorescence analysis. The practical reality of on-stream x-ray analysis has been achieved through effort over the past twenty years, marked by an occasional breakthrough, but more typically a step-by-step development to which many individuals and organizations have contributed. The net result of this progress is the present capability to install on-stream x-ray analyzer systems on a turn-key basis. It is now possible to provide all components of an x-ray analysis system as a completely engineered unit which can be put into immediate use, minimizing needs for specialized application knowledge to benefit from continuous assaying in process control. The economic factors which influence the choice of system and limitations of the x-ray fluorescence technique for slurry analysis are reviewed.

Jan 1, 1976

By R. L. Tobie

The degree of automation that has evolved in the dumping and hoisting of ore at the 3A and 3B hoisting shafts of the San Manuel mine is discussed. Motormen underground now dump their own trains at shaft pockets with rotary car dumps which operate semiautomatically. The ore is then drawn out of the 1200-ton shaft pockets into measuring baskets in skip loading stations, loaded into bottom-dump skips, hoisted, and dumped into coarse ore bins on the surface, in a fully automated operation. In an underground control room on the 2075 level midway between 3A and 3B shafts, car dumping, skip loading, and hoisting systems are monitored on lighted control panels which mimic each step in the operation. Here skip loading and dumping are viewed on closed-circuit television.

Jan 1, 1972

By Albert J. Phillip

Jan 1, 1947

Jan 1, 1884

By David Baker

When the skip-hoist was first tried as a means of filling the blast-furnace it made a great many enemies and very few friends among furnace managers. This state of affairs continued until the Duquesne furnaces were built, which demonstrated not only the possibilities of a furnace-stack in the way of production, but also the ability of the skip-hoist to charge the materials necessary to produce the large tonnlage obtained. Every furnace manager, who has operated stacks fitted with the vertical hoist and the hand-barrow system of filling, remembers that the momentous question about the furnace, particularly during a good run, was: "Are you keeping her full ?" and many a good run has been spoiled by the furnace " getting away from the men." With the new birth of the skip-hoist this trouble was eliminated ; but alas! Other and more important difficulties arose. The distribution of the stock, the importance of which is never learned until many different ores and fuels have been tried, demanded closer attention. With all the defects of the hand-barrow system, the distribution—When the top fillers were conscientious in carrying out the scheme of filling arranged after thoughtful consideration by the manager—mas above criticism. It is said that the modern skip-hoist, equipped with an elliptical hopper and receiving-cylinder, and discharging over a small bell into the main hopper, will give just as good results as those obtained with hand-barrow charging, but I cannot agree with this statement. I grant, that under very favorable conditions, the mechanical furnace-top will do apparently as well as the

Jan 1, 1905

By D. C. Buffum, L. D. Jaffee

THAT the path of brittle fracture in temper brit-tle steel differs from the path in unembrittled steel has been known for some years1 More recently it has been recognized that alloy steels, at least, display two forms of temper brittleness1 which may be called upper-nose and lower-nose. No experimental evidence has been published, however, to show that the two forms can be distinguished by simple inspection of brittle fractures. Fig. 1 is a photograph of the fractured surface of a V-notch Charpy specimen of SAE 3140 steel in which temper brittleness developed during heat treatment in the lower-nose temperature range.' The steel was austenitized 1 hr at 900°, tempered 1 hr at 675", and embrittled 48 hr at 500°C, with water-quenching after each treatment. The temperature of transition from ductile to brittle fracture in the Charpy test was + 2°C (criterion of transition: 100 pet fibrous). The hardness was Re 25; the austenite grain size ASTM 8. This specimen was broken at 150°C in the standard Charpy test and absorbed 6.6 ft-lb; its fracture was rated 0 pet fibrous. Fig. 1 shows that the fracture appeared rough to the naked eye. At the side of the specimen away from the notch (the side which was in compression during the test), the surface as a whole deviated sharply from a plane. At higher magnification, X60, the surface gave

Jan 1, 1959

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 W. S. Landis

IN brief, this is the story of an attempt to Americanize a process originally developed in Europe. The story will be recited in two sections, the first dealing with the process as developed by the European engineers; the second containing the improvements and modifications of American origin, together with some details of the operating results of the unit as finally assembled. Developments in other directions in this same field have not, up to the present, pointed out an economic future for the process, therefore our record here is largely a report of development progress. Whether some particularly favorable location will be found at some future time for a commercial installation cannot as yet be fore-told. The project is now at a standstill. The peculiar tools of the electrometallurgist should be of great interest to the zinc smelter. The low thermal efficiency of the zinc retort, its comparatively small-scale unit and its intermittent cycle as it stood in 1925, should make this art a particularly fertile field for the electric fur-nace. Yet in spite of years of work recorded in volumes of literature, and an expenditure of large sums of money, there is not a single electrothermic zinc smelter operating anywhere in the world. In this industry the electric furnace plays only a secondary part today.

Jan 1, 1936

By Y. C. Liu, G. A. Alers, S. S. Choi

In searching for an explanation for the obvious difference between the copper and the brass type of rolling texture, it is common practice to look for correlations with other properties. For example, there are obvious differences between copper and brass in the critical resolved shear stress, the extent of easy glide or stage I, and the amount of "overshooting)) during single-crystal deformation.' Also, the slip lines in copper are fine and wavy while those in brass are more coarse and better described as slip bands.' Since neutron irradiation is known to make these properties in copper change in such a way as to resemble brass,2'3 an excellent test for these possible correlations is to see whether neutron irradiation produces a corresponding change in the texture, i.e., whether irradiated copper develops a brass-type rolling texture. The experiment would also answer the more important question of whether or not lattice defects like those introduced by neutron irradiation have any effect on the development of rolling textures in fcc metals. Experimental studies using conventional X-ray pole figure techniques are inconvenient because the X-ray detection system must be modified to discriminate against the radioactivity which is induced in the specimen by the necessarily long exposure to neutrons. Nevertheless, some texture determinations have been

Jan 1, 1968