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Chairman James F. Kemp :—I call upon Prof. Albert Sau-veur to open the general discussion on the subject of sound steel ingots. Albert Sauveur, Cambridge, Mass.:—I believe that I have the privilege, this instant, of opening one of the most important, significant and far-reaching discussions ever held before this Institute. I believe that our talk this morning will be heard far and wide, not only on this side of the water, but also on the other side. Everywhere, in short, where steel is manufactured. I welcome the opportunity of expressing my mind in regard to the production of sound steel ingots, a subject about which I entertain Rome very decided opinions. I shall not attempt to discuss the relative merits of the various processes that have been described. I shall, on the contrary, confine myself to a general consideration of the important questions before us. So intensely do I feel regarding the production of sound steel ingots that I have put my remarks on paper in my desire to present my views. I have always remembered my astonishment, not to say dismay, some twenty years ago, when I beheld for the first time a steel ingot, a rail steel ingot, that had been split open from top to bottom. There was the pipe! There was an enormous cavity extending from a short distance from the top to nearly one-third of the length of the ingot; and when I was told that manufacturers seldom discarded more than one-tenth of the total length of the ingot it became evident to me that a large proportion of piped, and therefore, defective, or at least weak and dangerous, rails were manufactured; in fact, probably one rail out of six, nearly 17 per cent., of dangerous rails.

Jan 1, 1914

By James Gayley

The atmosphere, which plays such an important part in the manufacture of iron and steel, is the most variable element involved in its several processes; and particularly is this true of the blast-furnace process, which consumes air in large quantitiee. At no time since the blast-furnace became an important and widely used apparatus—even when it was operated in the most crude manner—have the variations in composition of the raw materials used been as frequent and as great as the variations in humidity of the atmosphere. Important improvements have been made in the blast-furnace and its accessories, such as the hot-blast stoves, the increase in size and change in the shape of the furnace, more efficient blowing-engines, the increased protection given to the bosh-walls, and the careful preparation of the raw material, all of which have exerted a pronounced influence on the furnace-operations from a metallurgical standpoint. But during the past eight years little advance has been made in this direction; the fuel-consumption has not diminished, nor has there been any material increase in production. Within that period, however, there has been witnessed the greatest development in appliances for the economical handling of material. So complete has been the work in this direction, that, except in isolated cases, in this country at least, a further extension does not hold out much promise of a satisfactory return on the investment required. It seemed that, with the exception of the gas-engine, we had about reached the limit, for like a strong wall, the atmosphere, with its humidity as variable to-day as when first blown into a primitive blast-furnace, appeared to stand as a barrier to

Jan 1, 1905

By Irwin Roman

IT has been known for many years that when a wire is moved in a magnetic field, an electromotive force is developed which is proportional to the rate at which the wire is moved in a direction perpendicular to the magnetic intensity and to the magnetic intensity itself. If the ends of the wire are connected to a current indicator, the current behaves exactly as though the source of electromotive force were a galvanic cell. If a wire is wound circularly and rotated uniformly around a diameter not parallel to the intensity, the current flowing through the wire will be alternating of sinusoidal shape. If, instead of a single loop, there are several turns wound in a short helix, the electromotive force developed will be approximately proportional to the number of turns, the area of the helix and to the speed of rotation. The maxi-mum electromotive force will be devel-oped when the axis of rotation is perpen- dicular to the field; if this is not so, only the component of the intensity that is perpendicular to the axis of rotation is effective. This is the principle of the usual earth inductor. With a few turns of wire and comparatively slow rotation, FIG. 1.-MAGNETIC GRADIOMETER. it is possible to produce a considerable deflection of a galvanometer. If two similar coils are rotated together at two different points for which the magnetic field intensities perpendicular to the axes of rotation are different, the electromotive forces developed will each depend on its corresponding intensity and be a measure of that intensity. If the inten-sities are sufficiently different so that the electromotive forces may be compared, the two intensities may be compared. This is the principle

Jan 1, 1934

By Nathan C. Rockwood

LIME is a very general term applied to products of limestone, in popular treatises often incorrectly, including ground or pulverized limestone used in agriculture. When used without qualifying adjective, the term usually means burned or calcined limestone, or quicklime, or calcia. The corresponding calcined product of magnesite is magnesia. If the calcined rock is relatively pure calcium carbonate, the resulting lime is a "high-calcium" lime; if the rock is dolomite, or a combination of calcium and magnesium carbonates, the lime is a "dolomitic" or a "high- magnesium" lime. There are various grades in between, depending on the percentage of magnesium carbonate and other ingredients in the raw rock. For some industrial purposes only high-calcium limes are suitable; in other processing-as, for example, neutralizing acid wastes -the relative percentages of magnesium and calcium carbonates in the raw material are not important. Limestone is burned (roasted or calcined) in furnaces known as lime kilns by direct exposure to the hot gases and flames. When heated to incandescence, the carbon dioxide content of the rock is expelled, leaving calcium and magnesium oxides, according to the formula usually written: [ ] This thermal reaction is reversible, which requires that the lime be withdrawn from the "calcining zone" of the kiln about as fast as made. Pure calcium carbonate would lose 44 pct of its weight in the calcining process; dolomite, 48 pct. Generally, the lime will retain the approximate size and shape of the piece of rock from which it is made but some few limestones tend to break down into granules or dust. Hence lime (quicklime) comes from the kilns in lumps or granules and normally is packed in water- tight containers in these forms, or is pulverized after calcination.

Jan 1, 1949

By C. E. Dobbin

THE identification of rock formations by a study of certain physical characteristics of burned samples was introduced in Wyoming in 1,926, when W. G. Buckles, superintendent. of the brick department of the Parco Development Co., reported to officials of the Producers & Refiners Corpn. that shales from the Cretaceous and older formations exposed between Parco and Rawlins exhibited distinctive coloration and textural features when burned in a standard brick kiln at temperatures ranging between 1000° and 3000° F. In collaboration with Elfred Beck, chief geologist of the Producers & Refiners Corpn., Buckles later burned cuttings and cores from several Wyoming wildcat wells in a standard kiln and successfully identified certain subsurface formations which had not been satisfactorily identified by other means. The results of their investigations were outlined in papers presented by Beck before the American Association of Petroleum Geologists at San Francisco in March, 1928, and by Buckles at. a joint meeting of the Rocky Mountain Oil and Gas Association and the Production Division of the American Petroleum Institute at Casper in November, 1928. These papers have not been published. The investigations set forth in this paper were carried out for. the purpose of determining the value of certain ceramic tests in assisting the petroleum engineers of the U. S. Geological Survey to identify well cuttings that represent Cretaceous shales penetrated beneath unconformable Tertiary formations in central, and eastern Wyoming, but that yield neither lithologic nor paleontologic criteria for satisfactory correlations with distinctive weathered outcrops. The investigations were made in the chemical laboratories of the Geological Survey at- Midwest, Wyo., and consisted of studying certain physical characteristics of burned bricks from representative outcrop samples of unweathered Cretaceous shales and of similarly burned cuttings of the same shales collected from wells in the Salt Creek oil field.

Jan 1, 1931

By A. B. Irwin

Abstract The techniques used in recognizing, recording, and interpreting structures in the Slocan sedimentary ceries in the West Kootenay district of B.C. are presented here in the hope that they will be of use to others working in complexly folded areas. The general pattern of folding in the Central Slocan area is obscured by lack of outcrop over a large part of the country, lack of marker horizons, local complexities of folding, and several systems of faulting. 1t was found necessary to observe and record in great detail all primary and secondary structural features and to analyse those observations on a statistical basis. The determination of bedding tops as well as bedding attitudes proved to be of fundamental importance in determining the pattern of folding. The interpretation of secondary linear and planar structures confirm:; this pattern. Accordingly, the thickness of the Slocan sedimentary series is computed to be several times that formerly postulated. Introduction The data upon which this paper is based were collected largely during the field seasons of 1947 and 1948 when the writer was employed by the British Columbia Department of Mines on detailed mapping in the Slocan mining camp. Additional observations were made by the writer during 1950 when engaged in property examinations for the Geological Survey of Canada. This presentation is largely a condensation of part of a more comprehensive thesis (5) and is restricted to observations and conclusions pertaining to the mapping of complex folds, stripped of any hypothetical discussion. Except for some unique occurrences of primary structures, there are no features or techniques described here which are not presented in standard textbooks on structural geology. It is felt that the major contribution of this paper is the method used in applying these standard techniques to a specific field problem and in interpreting the results.

Jan 1, 1951

By W. M. Weigel

The general term "sand" applies to a multitude of similar materials consisting of fine granular mineral. As usually understood, it means the ordinary natural product used for structural purposes and made up largely of grains of quartz. Quartz sand constitutes by far the greater bulk of the production, but there are other grades used for industrial purposes, such as molding sand, glass sand and many others, that may be grouped under the general name of special sands. Under this general group would fall filter sand, sand-blast sand, engine sand, potter's sand, abrasive sands of all kinds, sand for pulverizing, roofing sand, flooring sand, fire or furnace sand, standard sand, burnishing sand, sand for magnesium oxychloride cement-plasters and sand for chemical and metallurgical purposes. Sources of Supply Sand is a widely distributed natural product and even the better grades are low-priced commodities. For these reasons development has occurred near points of consumption where sand meeting the requirements is available. Some special grades, however, cannot be prepared from any sand bed and shipments are often made over considerable distances when the only developed deposit is remote from the consuming center. This is true of filter sand, sand-blast sand, sand for pulverizing and some of the others when chemical purity or grain size, coupled with the need of a properly equipped plant for preparation, are required. New Jersey is a large producer of filter, engine, sand-blast, fire, and pulverizing sand. Pennsylvania, and West Virginia produce special sands for pulverizing, fire sand, abrasive sand, engine sand and sand for chemical and metallurgical use. Ohio produces much sand-blast, fire and abrasive sand, and some filter sand. Illinois and Minnesota produce

Jan 1, 1926

By Robert C. Speck

Floor heave or deformation of the mine floor into the mine opening is a problem which has plagued coal mines in this country and others. In mining areas where room and pillar mining is practiced, floor heave generally occurs when the stress applied to the floor material by a coal pillar exceeds the bearing capacity of the floor strata. When the floor strata beneath the coal pillar fail, the pillar moves downward and displaces the material under it. This material, in turn, moves outward and upward into the mine opening (Figure 1). As the underlying materials fail, the load supported by the coal pillar may be transferred to adjacent pillars. If these are marginally stable, they too may become overloaded and push into the floor. Thus, floor heave can spread through a large portion of the mine in a progressive manner. As the pillars push into the floor, differential movement and flexure of the roof strata may cause them to weaken and fail, resulting in subsidence of the ground surface above the mine. This paper describes the problem as it was manifested in the Zeigler Coal Company No. 5 and Murdock room and pillar coal mines near Murdock, Illinois, and reports the results of a U. S. Bureau of Mines- sponsored study conducted by the University of Missouri-Rolla. During the course of the study, floor heave in the two mines hindered the transportation of men, machines, and coal to and from the working mine-face, interrupted ventilation plans, drastically increased roadway maintenance costs, intensified safety and strata control problems, destroyed large pieces of equipment, and, several times, pre- vented access to otherwise minable coal resources. The ultimate objective of the study was to develop one or more simple procedures to allow detection of a potential floor heave problem during the exploration phase of mine design--before initiation of production mining.

Jan 1, 1981

By Charles G. Maier

It has long been supposed that when crystalline materials are comminuted the energy used in the production of increasingly smaller grain sizes is not entirely dissipated as heat but that a certain portion is "stored" as a part of the internal energy of the material. This portion usually has been called the "surface energy" of the particles. The practical interest of the Bureau of Mines in this subject in connection with the energy requirements of crushing processes has led to the author's attempt to measure the "stored" energy in finely divided calcite by heat-of-solution methods1.t The experiments on calcite showed that "storage" of energy could not be proved for this material, because fine grinding caused a lack of chemical homogeneity evidenced by loss of carbon dioxide and subsequent adsorption of water on the surfaces of the calcite particles. When thermochemical correction was made for composition changes the corrected heat of solution was less for fine material than for coarse. Continuation of the experimental work into the problem of comparing work and heat in the deformation of metallic crystals, where the calorimetric difficulties were less, showed, however, that in the case of copper and aluminum a real discrepancy between work and heat could be shown. Similar results had previously been obtained by Farren and Taylor2 and Hort3 and more or less simultaneously with the author's work by Rosenhain and Stott4 and by Taylor and Quinney9 The results obtained by the different investigators were not satisfactorily consistent, but the experiments of Taylor and Quinney constitute by far the best figures obtained to date. The previous paper1 presented evidence to show that if energy is stored in the surfaces of crystals the densities of fine crystals should differ

Jan 1, 1936

There are bound to be changes with age, so I should not have been surprised or disappointed when what I had considered as high ad- ventures were much fewer and more widely scattered in the last 20 years of my long and active business life. But such adventures came until I was past 80 years of age and no one could expect more than this. Frequent visits to mines in this country and Canada and directorships in Bralorne and its subsidiaries, Homestake Mining Co., Bradley Mining Co., and the Bunker Hill Co.; and Copper Range Co. and its great new White Pine mine in Michigan, lasted far beyond the usual retirement age. The least happy part of my last two decades of active life was the death or sickness of many of my old friends. Hubert d'Autremont, whose friendship no one could replace, died suddenly in 1946. Henry Carlisle and Temple Bridgeman, for many years office associates, had heart attacks that cut down their activities far too soon. Many other less intimate friends died or became ill, but I knew that with advancing years such losses were inevitable. These memoirs would be endless if they covered all of the unusual work and associations I found in the last 20 years. So I must confine the rest of my recollections to expeditions that would have thrilled any engineer at any time. Masaro Mine, Mindanao, Philippines The first of the four "high adventures" came late in 1949, when I was 65 years old. For over a month I had been discussing reported rich lead-silver-copper properties in the Philippines with Thayer Lindsley and other officers of Panaminas. A competent and agreeable "Elderly" (not as old as I was) engineer named Ward Williams had talked with Thayer about high grade mines in a remote part of the

Jan 1, 1976

By C. H. Mathewson, Kent R. Van Horn

Copper and the copper-base solid solutions readily form twin crystals when plastically deformed at a suitably elevated temperature or annealed after cold deformation. In fact, no feature of the microstructure of these materials is more prominent or characteristic than these straight-sided bands or simple lines of division which sometimes come from groups of thin polysynthetic lamellae, penetrating part way or wholly through the parent grain substance, but often divide the grain into a few or perhaps only two crystallographically related parts. Nearly always the bands as seen in the usual microscopic examination of a specimen come into vivid contrast with the adjacent crystalline material owing to the inherent difference in orientation. Bands which under special conditions of orientation cannot be seen with vertically incident light are often visible under oblique illumination and, when this fails, contrasting effects usually may be obtained by using polarized light. There is no longer any doubt that these synthetic banded structures obtained in the ordinary course of working and annealing are due to twinning of the spinel type which was observed long ago in a number of metals crystallizing in the isometric system.' It has been customary in metallurgical literature to designate these synthetic twins, which grow into prominence during an annealing process, as "annealing twins" without regard to the actual mode of their formation, which is, indeed, obscure and with scant recognition of the fact that prior deformation is essential, no twins having been observed in metal of known unstrained history. This is questionable; especially in view of the fact that in a number of metals and minerals, reorientation into the twin configuration is known to occur as a result of a simple shearing mechanism along the recognized twinning planes and the

Jan 1, 1930

By D. E. Wolfson, H. J. Gluskoter, M. R. Geer, John A. Harrison, H. F. Yancey, I. S. Latimer

When this chapter was prepared for the kst edition in 1942, continuous mining machines virtually were unknown, and hand loading in underground mines, which gave an opportunity to discard impurities, accounted for 55 percent of the production of bituminous coal and lignite as compared with the 1965 figure of 11 percent. Only 24 percent of the total production was cleaned mechanically, compared with the present (1965) figure of 65 percent. The amount of refuse discarded during preparation for the same period increased from 13 to 21 percent. Changes in the equipment used in the cleaning process were as follows: [ ] Unclassified nearly 8 percent. Data on the amount cleaned by flotation was not collected until 1960 when 1.8 million net tons was so treated. In 1965 this figure increased to 6.9 million tons. Although the great increase in mechanization and full seam mining has resulted in substantial increases in the impurity content of the raw coal as well as in a finer size consist, some phases of face preparation are still important, particularly the variability of the distribution and thickness of the interbedded impurities and the changes in the character of the roof and floor from place to place in the mine. Knowledge of these factors in relation to all phases of the mining operation, particularly selective mining, are still of importance to the treatment of raw coal in the preparation plant. The major characteristics of coal and impurities from the standpoint of mechanical cleaning are particle size composition, generally called size consist, density differences, the relative friability of the coal and of its associated impurities, hardness, and strength. Some of the other factors related to preparation are petrographic composition and rank. COAL PROPERTIES Rank Perhaps 95 percent or more of the coal cleaned mechanically is of bituminous rank. Only a very small tonnage is subbituminous and prac-

Jan 1, 1968

By G. S. Scott, G. W. Jones

"INTRODUCTION In the course of the investigation the Bureau of Mines is carrying on to determine the causes, behavior, a. control of mine fires, the detection of incipient heating underground in the mines and above ground in refuse banks has received consideration.Many of the anthracite fires have been active for years and have progressed considerable distances free their original source.Some of the fires are in inaccessible territory, and it is often impossible to determine with any degree of accuracy their exact location or even the veins of coal that are afire, especially when the fire is in the upper strata and when it is impossible to go underground because of flooded conditions or the presence of an irrespirable atmosphere.In such cases, the only means by which the trend of a fire may be ascertained (as a result of any fire-fighting methods that may have been employed) are the sampling, exanination, and interpretation of the gaseous products coming from the fire area. The most important information desired is to know whether the temperature in the heated area is increasing or decreasing and to determine whether a fire that has been sealed is cooling down to normal mine temperatures or is maintaining its heat or is increasing in intensity due to infiltration of outside air.Interpretation of the analyses of gaseous products from refuse banks on the surface also should be of value in combating such fires. Refuse bank fires, with the additional danger of starting an underground fire through ignition of the outcrop, are by no means unknown in the anthracite coal region, and the causes of such fires are not always apparent. In a few cases the causes have been strongly suggestive of spontaneous origin."

Jun 1, 1938

By T. Lane Carter

It is a curious fact that while in our Transactions there are papers dealing with mining-districts in all parts of the world, in Europe, Asia, Africa, and Australia, there is not one which describes the mining possibilities of Nicaragua, our near neighbor. To be most interested in distant objects, like the moon, and to neglect what lies at our feet, appears to be a trait of human nature. The neglect of Nicaragua is not confined to the American Institute of Mining Engineers. In no other transactions am I able to find papers dealing with mining in Nicaragua, some parts of which are as much in need of discovery and research as the North Pole. I hope this paper will be the precursor of many others to be printed in our Transaclions, dealing not only with the miniilg possibilities of Nicaragua, but with the whole of Central America, where there are vast areas a,waiting skill and capital for their development. Much of this capital and skill should come from the United States in the future, although it is probable that European capitalists, when they appreciate fully the possibilities, will investigate more and more the mining-resources of Nicaragua and ot'her Central American republics. Fig. 1 is a sketch-map of Nicaragua showing the principal mining-districts. 11. History. Mining in Nicaragua did not begin yesterday. It was commenced by civilized man when the Spanish conquerors pene-' trated into the interior and forced the natives to procure the precious metal for them. It is strange that the Spaniards did not find more gold, and work on a scale as extensive as in Colombia and other parts of South America. Probably in Nicaragua the Indians covered up most of the rich prospects

Jan 1, 1911

By A. B. Calhoun

These mines, which belong to the Burma Corporation, Ltd., formerly a London company now incorporated in Rangoon, Burma, are situated in the semi-independent state of Tawng-Peng, one of the small divisions comprising the northern Shan states and erroneously known as part of Upper Burma. Bawdwin is approximately 23' 6' N. latitude and 97" 20' E. longitude, 450 miles north of Rangoon, 169 miles northcast of Mandalay and 50 miles south and west of the Province of Yunnan, China (see Fig. 1). Although the mines were worked by the Chinese during the Ming Dynasty, 1412 A. D., the most extensive operations took place between 1796 and 1851, when the mines contributed largely to the silver market of China. During the reign of Tung Chik, 1868 A. D., they were abandoned partly because of the Mohammedan rebellion in Yunnan, which made life and property insecure, but largely because of the difficulty of operating the mines on account of water and poor ventilation. Since that time practically nothing was done, although the Burmese kings are said to have made several sporadic attempts to work the mines, until 1891 when Europeans were attracted by the great slag dumps (assaying about 40 per cent. lead) which the Chinese had left after extracting the silver. After a railroad and smelter had been built and 200,000 to 300,000 tons of slag smelted for lead, exploration work was started and old workings cleaned out in order to locate the remnants of the orebody that it was supposed the Chinese had left. After two years of most discouraging work, the remains of a large orebody was discovered by the Dead Chinaman Tunnel or what is the 171-ft., or No. 2 level adit. From then on the development was rapid and today the Chinaman is considered one of

Jan 1, 1923

By Joe Keane

DOUG HALBE: The kickoff speaker, and my unanimous choice, is Joe Keane. Joe was born in Butte, Montana, and began his association with the mining industry as an under- ground miner at age 16. Currently he is president of KD Engineering and Metcon Research. He had it lucky when he went to school because there were only 44 elements in the periodic table, I understand. [laughter] Here's Joe. JOE KEANE: I'm doing this under protest. Maybe we can start the slides. Mr. Halbe gave me this topic, but I don't like it. I don't like Mr. Halbe either [laughter] because of the way he shanghaied me into this. He called me up on the phone and said this is what you're going to speak about: "Five Things I Never Want to See Again in Plant Design," and I said, "Huh!" Then I started getting stuff from SME about how to make a presentation. I have decided to change the title to "More Than Five Things I Never Want to See in Plant Design," since you can't have a completely negative speech; you have to have other topics. So we will have some other, not completely nonrelated, topics to sort of break the tension. I tried to find a joke to open with. I talked to Omar Mutati. All of his jokes were either about Bill Clinton, our beloved President, or they were too filthy to say in a mixed group. [laughter] So I decided to start this out with a profound statement. The pro- found statement is, "The meek shall inherit the earth, but not the mineral rights," [laughter] by J. Paul Getty. J. Paul Getty was one of my favorite guys because when a real obnoxious reporter asked him one day, "How can I become wealthy?" he said, "Drill for oil and find it."

Jan 1, 1998

By Robert B. Parsons

"The pendulum in Ottawa has swung dramatically from fiscal policy to monetary policy over the last several years. International trends indicate that the pendulum has to start its swing the other way, if Canada's mining industry is to maintain its preeminent position in the global mining arena. This article, which is based on a paper presented by the author at the 37th Annual Meeting of the Newfoundland Branch of CIM, identifies these trends and how they could interact with Canadian policy.IntroductionThe title of this paper is not a very imaginative or catchy one, but it states the topic quite succinctly, if not tersely. This paper looks into a crystal ball to see what might be in store for mine financing over the balance of the current decade.In the event that the reader feels some trepidation about the prospect that such a paper could seek to be the definitive work on the subject, it should be made clear at the outset that this is not the case. The author is, after all, not an economist, a scholar, a financial analyst, or a soothsayer, but is rather a simple accountant who has been closely involved with the mining industry, and the financing thereof, for some twenty years.The paper recognizes that, while a mine may be born when production begins, the mine is conceived when exploration starts. As this act of conception is obviously an essential part of mining, the financing of exploration is also covered in this paper. To attain a focus, this paper approaches the topic of mine financing in the nineties as follows: first, the major emerging forces in the industry are identified: and, second, the implications of each of these forces on financing are considered."

Jan 1, 1991

By A. B. Calhoun

These mines, which belong to the Burma Corporation, Ltd., formerly a London company now incorporated in Rangoon, Burma, are situated in the semi-independent state of Tawng-Peng, one of the small divisions comprising the northern Shan states and erroneously known as part of Upper Burma. Bawdwin is approximately 23' 6' N. latitude and 97" 20' E. longitude, 450 miles north of Rangoon, 169 miles northcast of Mandalay and 50 miles south and west of the Province of Yunnan, China (see Fig. 1). Although the mines were worked by the Chinese during the Ming Dynasty, 1412 A. D., the most extensive operations took place between 1796 and 1851, when the mines contributed largely to the silver market of China. During the reign of Tung Chik, 1868 A. D., they were abandoned partly because of the Mohammedan rebellion in Yunnan, which made life and property insecure, but largely because of the difficulty of operating the mines on account of water and poor ventilation. Since that time practically nothing was done, although the Burmese kings are said to have made several sporadic attempts to work the mines, until 1891 when Europeans were attracted by the great slag dumps (assaying about 40 per cent. lead) which the Chinese had left after extracting the silver. After a railroad and smelter had been built and 200,000 to 300,000 tons of slag smelted for lead, exploration work was started and old workings cleaned out in order to locate the remnants of the orebody that it was supposed the Chinese had left. After two years of most discouraging work, the remains of a large orebody was discovered by the Dead Chinaman Tunnel or what is the 171-ft., or No. 2 level adit. From then on the development was rapid and today the Chinaman is considered one of

Jan 1, 1923

A great range of contacting equipment is used in solvent extraction. However, a tower filled with a regular packing offers many advantages in the direct extraction from slurries. A study was made of the flow of a dense slurry through a packed tower in which the continuous phase was kerosene. The grid type packing, which was preferentially wetted by the slurry, had slats inclined at an angle of 30¦, to the horizontal. On the sur- face of the slats there were uniformly spaced longitudinal indentat- ions. These were of a height slightly less than the film thickness and divided the slurry discharging from the bottom of the slats into a number of uniform streams. When slurry entered the tower it was distributed by means of a troughs and weirs type of distributor. Because of the relatively high slurry velocities that occur at the entry region, it was necess- ary to have the distributor and the first two grids above the solvent level. The interface at the bottom of the tower was located at the mid-point of the bottom grid, so that the slurry entered the interface as a continuous film across the full width of the slats. Using the above system, stable flow with low entrainment was achieved at slurry flow rates of 3.4 mis/cm/sec. This would be equivalent to a flow rate of 177 gallons per minute through a tower of cross-section 4 ft 4 in. by 4 ft 10 in., or 1200 tons per day of solids of specific gravity 2.6 when the pulp density was 65 per cent. Previous tests indicated that a total tower height of about 30 ft would be required for a recovery of better than 99 per cent.

Jan 1, 1969

By G. Horvay, J. G. Henzel

Nomograms and charts are provided which permit rapid determination of the mold-casting interFace temperature and the speed of solidification when a semiinfinite ingot is cast into a semiinfinite mold. The physical properties of the mold, the frozen metal, and the liquid metal are not assumed to be equal, but they are assumed to be temperature independent. The results are correlated with charts prepared by Paschkis and Hlinka—using Columbia University's Analog Computer—for the freezing of finite ingot slabs when a constant surface temperature is impressed, and with experimental cooling curves obtained by Pellini in sand and iron molds for 7 in.-sq steel castings. x = coordinate directed to right of zero (freezing direction) y = coordinate directed to left of zero (melting direction) e = position of freezing front (in x direction) ? = position of melting front (in y direction) $ = temperature (function of position and time) ? = fixed temperature 2L = width of finite slab Y = a fixed position in the semiinfinite mold, or the width of a finite mold (see Section 7) Properties y = density, lb per cu ft c = specific heat, Btu per lb deg F k = conductivity, Btu per ft hr deg F X = heat of fusion, Btu per lb k = k/Yc = temperature diffusivity, sq ft per hr* b - = = - heat diffusivity, Btu per sq ft deg F Vhr Subscripts 2 = pertaining to the still-liquid metal (case of freezing), or the medium which furnishes the heat (case of melting) 1 = pertaining to solidified metal (case of freezing), or to molten metal (case of melting)* 0 = pertaining to mold (case of freezing), or to the still-solid metal (case of melting) f = pertaining to fusion condition (eg.,?f - fusion temperature) i = pertaining to the location x = 0 (the mold-ingot "interface")

Jan 1, 1960