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By F. C. Schora, H. P. Meissner

COUNTERCURRENT staged processes involving chemical reactions between solid and gas streams are becoming more common. Such operations are generally carried out in a series of fluidized beds with each bed acting as a stage. Fig. 1 is a schematic illustration of a series of stages located in a single column, with a solid stream moving down through this column from stage to stage counter to a rising gas stream. The reduction of iron oxides with hydrogen and carbon monoxide is one of the reactions which can be advantageously carried out in such a countercurrent system. Calculation of the performance of a countercur-

Jan 1, 1961

By J. Goldfield

Asbestos fiber, before it can be used commercially, is separated from the rock in which it is naturally found. Johns-Manville Corp. is currently constructing a 12-story fiber mill, of which the first half is completed and in operation. The mill will be the largest in the world, producing about 30 pct of the world's fiber. It was engineered and constructed by a cooperative effort of the engineers of the Canadian Johns-Manville Fibre Div. and the general plant engineering dept. Detailed design work on all phases of the job was done by Surveyer, Ninniger & Chenevert of Montreal. A series of crushing, screening, air aspirating and air separating processes will separate the fiber from 10 tons of rock per min. But to process this amount of ore about 90 tons of air per min will be handled in the aspirating and dust-collecting systems. To express this in more common units, 2.5 million cfm of air will be required. All this air will pass through a bag-type continuous automatic filter and will be expelled to atmosphere in summer or returned to the mill for heating during the winter months.

Nov 1, 1955

By Earle E. Schumacher, W. C. Ellis

For the purpose of developing combinations of higher strength and conductivity than are obtainable by heat treatment alone in the age-hardening copper alloys, an investigation has been made of the effects of combinations of heat treatment and strain hardening on the properties in question. The investigation was limited to a study of the alloys containing nickel and silicon; nickel, silicon and cadmium; and cobalt and silicon. The experiments made in the course of the study arc described in this paper in three groups: 1. The effect of hard drawing subsequent to heat trcatment on the mechanical and electrical properties of the alloys. 2. The effect of low-temperature aging on the properties of heat-treat,ed and hard-drawn alloys. 3. The effect of strain on the rate of aging of quenched nickel-silicon-copper alloys. Preparation and Compositions or the Alloys The alloys were prepared by melting cathode copper in an electric resistance furnace and adding sufficient of the hardening elements to bring the compositions to the desired values. The purities of the hardening elements were as high as could be obtained in commercial practice. The metals were what are designated in the trade as electrolytic nickel, cobalt rondelles, commercial stick cadmium and fused silicon. The alloys

Jan 1, 1931

By Charles A. Ashburner

The existence of natural gas-springs in Pennsylvania and the adjoining States west of the crest of the Allegheny Mountains was known to the earliest settlers. Possibly the first gas obtained from a well was at Fredonia, Chautauqua County, N. Y., where a well was sunk on the bank of Canadaway Creek, near the Main Street bridge, in 1821, and sufficient gas obtained for 30 burners, the inn having been illuminated by the gas when General Lafayette passed through the village about 1821. In 1858 another well was drilled, which supplied 200 burners. A still larger one was drilled to a depth of 1200 feet in 1871. According to Mr. E. J. Crissey, Secretary of the Fredonia Natural Gas Light Company, the average monthly supply of these wells in 1880 was 110,000 cubic feet. Since 1859, when the drilling of oil-wells in Western Pennsyl-

Jan 1, 1886

By Warren Weaver

SOME of the advantages of the inductive method of electrical prospecting were emphasized in a paper by Dr. Max Mason.1 Since this emphasis was misunderstood by some to indicate a too exclusive interest in inductive methods, we are especially happy to help correct this impression by reporting on some of our work on surface potential methods. EARTH CURRENTS AND SURFACE POTENTIALS When two electrodes, A and B, are placed on the surface of the ground a distance d apart, and a 100-volt battery is connected across the elec- FIG. 1.-LINES OF CURRENT FLOW AND SURFACE POTENTIAL IN MILLIVOLTS IN THE CASE OF A HOMOGENEOUS EARTH. trodes, current flows from the positive electrode A to the negative electrode B. The current does not pass directly from A to B along the straight line joining these two points. In fact, a negligible amount of the

Jan 1, 1928

By C. M. St. John

INTRODUCTION The stress redistribution accompanying the excavation of a deep tunnel may induce failure of the rock. The role of the support system is to control the extent of the failed region and hence to limit closure of the tunnel within an allowable amount. In such circumstances, the design of the support system is generally based on the Ground Reaction Curve (GRC). The GRC is the relationship between the support pressure and the induced displacement at the tunnel wall for a circular tunnel under hydrostatic loading. In the calculation of the GRC (see Brown et al. (1983) for an exhaustive list of reference), the rock is generally treated as an elastoplastic material characterized by cohesive-frictional yield strength and by dilatancy during plastic deformation. A recent analytical development (Detournay, 1983) has allowed the generalization of the GRC concept for some cases of non-hydrostatic in-situ stress fields (Detournay and Fairhurst, 1982). As an application of that development, this paper describes design charts that provide powerful means of performing parametric analysis for tunnels subject to non-hydrostatic loading. BACKGROUND The in-situ stress in a plane perpendicular to the tunnel axis can be decomposed into mean and deviatoric components, Po and So (see Fig. 1). Since it is assumed that the rock is characterized by a Mohr-Coulomb yield strength, the deviatoric invariant So must be less than the limiting value Sl0 given by

Jan 1, 1984

By W. W. Little

At the United Verde mine the 9-2D stope on the 4050 ft level is located within the north sulphide mass lying some 800 ft north of the main sulphide ore body. In 1948 it was estimated that this block contained 85,000 tons of ore at 4% copper and 9.2% zinc. The north ore body is a lenticular replacement deposit in the black schist, extending from about 100 ft above the 3750 level to a distance below the 4500 level yet to be determined. Although the mineralized zone approaches 1000 ft in length, only 300 ft is of economic importance. In width it varies from a maximum of 60 ft to about 3 ft at the north end, and is characterized by pinching and swelling in the ore zone. One of these larger swells is being mined as the 9-2D stope. Mining costs at greater depth, together with the expected grade of ore after dilution, necessitated a low cost mining method to permit profitable stoping operations. Based on the results obtained in a number of Canadian mines, it was decided to develop the ore body for stoping by the Aldermac or bench method of diamond drill blastholes; however, this plan was subsequently changed and the radial or ring method adopted. Such a method seemed to offer the advantage of large tonnages at low cost, and obviate the necessity of waste fill. This latter point was of particular importance, since the present waste system does not extend below the 3000 level.

Jan 4, 1950

By J. David Lowell

On a low desert ridge six miles south of Cairo lie the remains of the world's earliest known mining town, Maadi of predynastic Egypt. Copper artifacts, including ingots and an ax head which was spoiled in casting, indicate that copper ore was smelted in Maadi, and radio- carbon dating has placed the activity at least as early as 3300 B.C. This is the oldest documented date for the use of smelted copper, the first industrial metal used by man. Copper was mined and smelted almost as early in Asia Minor and on the island of Cyprus, but the greatest development of the budding copper industry was in Egypt, where specific historical records show that about 10,000 tons of copper metal were produced in the period from 1850-1580 B.C. Contrast this production of 35 tons per year with the present world production of about 7 million tpy.

Jan 1, 1970

By Oscar Aguilar, Jin-ichi Nakamura, Kazuo Nakamura

Michiquillay deposit is porphyry copper type with over 500 million tons of 0.70% Cu ore. In order to reflect the true nature of the orebody as to shape and value distribution and to compensate for insufficient data in the outer perimeter and lower portion, "Triangular Interpolation Method" is used in the computation, wherein block grades are determined by "Plane Regression". The results thus obtained are compared with the data from additional investigation and are found to match well with each other. Aside of total Cu, assays of Fe, S, MoS2 and geological data such as alterations, rock types, faults, mineralogical compositions are also stored in the computer. By this system, their distribution and relation to alteration become clear and classification of ore into types affecting recovery become possible. The outputs of this system make clear the characteristics of the orebody and furnish valuable geological data on the orebody.

Jan 1, 1976

By D. Torrey

Considering the two great interests of to-day, in iron upon the one hand and steel upon the other, and recognizing with measurable distinctness the peculiar fitness of each for special services to which they are applied, the proposition to unite the two metals in combination, to bring into simultaneous use the peculiar advantages which each offers, has great attractions. The limited success which has been attained by trying to bring about such combinations of the two metals through the use of fluxes in welding, has led to the general adoption of the opinion that an effective union of the two metals is impracticable, or to the view that if practicable it would have but limited commercial value. Such opinions are, I think, premature and erroneous, and having gained some knowledge of the character and value of the "Wheeler process" for welding iron and steel without the use of fluxes, I submit the following observations and opinions of the matter for your information, with the hope of eliciting such a discussion of the subject as it may require. The principle of the invention is to bring the two metals simultaneously to a welding heat in one pile, and then to manipulate it.

Jan 1, 1879

By John D. Ridge, Robert C. Barwick

The amount of lead in concentrates that moved in international trade in 1952 was only 16 pct of the world mine production of lead and was less than 27 pct of the total of lead in concentrates and lead metal that traveled from one country to another. Because almost all lead is derived from galena, lead concentrates are high grade, with a theoretical maximum of 86 pct lead, and can be shipped as such without transporting a considerable weight of waste material. It would not be surprising, therefore, to find the large share of lead in international trade moves in concentrates (Rule 5). This is not, as has just been mentioned, actually the case. There is more than one explanation for the situation. Lead smelting is not a particularly difficult process and is one for which smelting equipment can readily be made of the best size for the tonnage to be handled. Another factor that encourages local smelting is the effort of many mining countries to see that a maximum of profit from their raw materials remains in the home country. Still another factor is the newness of large scale lead mining in two of the three largest exporters of lead in concentrates. In these countries, South West Africa and French Morocco, there has not yet been time to erect enough smelting capacity to process all of the concentrate output. Even in these countries, however, it will not be long, if present trends continue and plans are fulfilled, before most or all of the lead mined is domestically smelted.

Sep 1, 1955

Covering resources, production, uses, defense impact, and future outlook of nickle, Mining Engineering presents the third in a series of articles on strategic minerals. Preceding it are "Cobalt" in January and "Sulphur" in May.

Jan 8, 1951

By Mark S. Childs

FRIEDENSVILLE orebody in Lehigh County, Pennsylvania, lies in the south central part of the USGS Allentown Quadrangle. Physiographically the area is located in a small reentrant-known as Saucon Valley-of the Great Valley Province into the Reading Prong of the New England uplift. Saucon Valley itself is an oval-shaped lowland eight miles long and four miles wide, surrounded by ridges except where connected with the Great Valley through a breach in the rim known as Saucon Gap. These ridges, composed of Pre-Cambrian metamorphic rocks and Cambrian quartzites, rise some 500 ft above the valley floor. They are continuous with the New Jersey Highlands. The valley lowland is immediately underlain by lower Paleozoic dolomites and limestones. This area is one of low relief having a swing of approximately 100 ft, with an average elevation of 375 ft above sea level. The entire valley, which has a water shed of about 58 sq miles, is drained by Saucon Creek. This unit flows in a northeasterly direction to the Saucon Gap, where it discharges into the Lehigh River.

Jan 1, 1957

By Peter G. Chamberlain

Many mining engineers considering in place leaching for the first time are uncertain as to how to evaluate ore bodies for potential leachability. Evidence presented in this report emphasizes the critical role of permeability in such evaluations. Whether an engineer is considering leaching "tight" formations typified by the porphyry copper deposits of the southwest or the permeable uraniferous sandstones of Texas and Wyoming, permeability measurements are the keystone of any testing program. Permeability tests range from cheap and easy to highly expensive and sophisticated operations. Constant head, variable head, and pumping tests all have application in evaluating ore bodies for in-place leaching. Costs of these tests will not unduly deflate the pocketbooks of most mining companies. The basic procedures for selecting and running these field tests--including preparing suitable wells--are reviewed for the benefit of newcomers to in-place leaching.

Jan 1, 1979

By John Wulff, R. Buehl, H. Hollomon

Although the main features of the transformations occurring in 18-8 have been published already, certain conclusions merit questioning and discussion. The questions may be summarized as follows : 1. If ferrite is formed by cold-working austenite, what happens to the carbon with which the ferrite and austenitc are both presumably supersaturated? 2. What is the nature of the alpha-ferrite formed at grain boundarices by chromium-carbide precipitation at these boundaries?

Jan 1, 1940

By R. Gilman Brown

Mines are interesting by reason of what they have done for man, or of what has been done for them by nature. Not all are interesting on both scores. Many profitable mines are commonplace to the geologist; and many presenting unique gcological conditions have been sad failures commercially. The Standard group at Bodie has produced in 25 years, $14,500,000, paying $5,000,000 in dividends.' On the other hand, this output has beeu mined (almost wholly above the 1,000-ft. level) from a system of more than 100 veins, ranging in thickness from 0.5 in. of ('specimen rock" to 30 ft, of clay and quartz; distributed through a zone about 2,000 ft, in width, and representing from three to five distinct periods of formation. This group, therefore, by reason of its industrial record as well as its geological features, may fairly be regarded as doubly interesting. The Bodie district occupies an island of recent (Tertiary) hornblende-andesite, surrounded by a complex of igneous rocks and breccias. It lies at the summit of the eastern foot-hills of the Sierra Nevada mountains, and within the Great Basin, a

Jan 1, 1908

The Library of .the above-named Societies is open from 9 A.M. to 9 P.M. on all week-days; except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining-maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may he what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining-reports, maps privately issued, and similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 6, 1913

By Arne Paus-Jenssen

Some aspects of the policies developed by Saskatchewan with respect to the provincial potash industry are discussed. The provincial potash policy was developed initially to deal with problems associated with an excess supply and consisted of output restrictions and floor prices. Changing market conditions led to a situation of rapidly increasing prices and revenues for the potash producers, and the nature of the policy problem switched from one of stabilizing the industry to one of levying increased taxes to enable the government to capture a portion of the revenues. The first part of the paper explains why a provincial potash policy was developed, the problems it attempted to deal with and how. The second part is an attempt to examine, from a public policy point of view, the impact of these policies on the potash industry.

Jan 1, 1977

By D. A. Dahlstrom

THE necessity for slime elimination from valuable mineral and coal products has become increasingly significant within the past 5 years.1,2 Most of the mechanized mining and present beneficiation methods have resulted in larger tonnages of extreme fines, silts, and clay, commonly called slimes, processed by the preparation plant. Economics in turn have forced the plant operator constantly to lower the bottom size of effective beneficiation, necessitating an almost complete recovery of valuable solids regardless of particle size. When these important factors are considered, the need for an efficient slime removal method for fine solids becomes self-evident. Ordinarily slimes have been classified as ranging from 75 microns, or 200 mesh, down to colloidal dimensions of less than one micron. At the same time there is general agreement that the most troublesome slimes are primarily clays, silts and extreme fines, so that the actual top size may be placed at approximately 30 to 40 microns. This immediately restricts any desliming operation to classification, as screening or other methods would be both uneconomical and grossly inefficient at such dimensions. The liquid-solid cyclone has been recognized as one of the most efficient fine size classifiers available to the mining industry. Applications of cyclones to thickening, high efficiency solid recovery, degritting,

Jan 1, 1952

By Linda P. Bono

Some mining engineers are pursuing their destinies in places far removed from what they might have envisioned back in the classroom. The path they follow to work each day may wind down Wall St., Park Avenue, LaSalle, or Market; their offices are in modern skyscrapers which offer all the amenities-air conditioning, thick carpets, attractive decor, and executive lunchrooms, to name just a few. The papers on their desks are a combination of financial figures and feasibility studies. But even in these surroundings there are indications of what these men do and where their professional interests lie-minerals are everywhere, from vast collections to one symbolic paperweight. . . there are sometimes specks of dirt under fingernails from a recent on-site inspection, belying the traditional banker's garb. . . and there are the wistful comments about finding it necessary to get out in the field.

Jan 9, 1978