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By DR. DOUGLAS

Discussion of the Paper of Dr. Douglas, presented at the Toronto Meeting of the Institute, July, 1907 (Trans., xxxviii., 455 to 471). EDGAR HALL, Silverspur, Queensland, Australia (communication to the Secretary*) :-Dr. Douglas has written on this subject before, and his influence has had a powerful effect on the side of freedom among the younger generation of engineers. Moreover, it is not the first time that he has attributed the decline of the copper-smelting industry in Swansea to the secrecy maintained by the firms there engaged in smelting-operations. In this latter statement I think his conclusions are open to criticism. Whether the firms referred to have suffered by their secrecy is their own business-I. bold no brief for them ; but that the decline of the copper-industry at Swansea was inevitable seems to me to be proved conclusively by Dr. Douglas's own writings. In his paper on The Copper Situation,1 Dr. Douglas says "In comparing iron and copper mining, . . . it must be remembered that 2 tons of average iron ore from the most prolific source now available will make 1 ton of metal; whereas from 33 to 75 tons (say an average of 50 tons) of copper ore must be mined to produce 1 ton of copper." And further: "Last year's production of iron was made from approximately 50,000,000 tons of ore. Our copper mines, to yield a production of 900,000,000 pounds, must have handled approximately 22,000,000 tons of ore, or nearly half the quantity raised from our iron mines." Is not this the key to the whole situation ? In transporting the 50,000,000 tons of iron-ore, 25,000,000 tons of the metal iron were carried so much nearer to the market, but the transportation of 22,000,000 tons of copper-ore would have carried only 450,000 tons of the metal copper nearer to its ultimate destination. The small percentage of copper available in its ores makes

Sep 1, 1908

By Paul J. Sirkegian

The problem of properly controlling the movements of underground trains in the Emma Nevada and Morris Brooks workings of the Consolidated Coppermines Corporation of Kimberly, Nev., became more complex as the rate of production increased. Ore from these mines, which are connected through a 7000-ft. single-track haulageway (Fig. I), is hoisted through the Emma Nevada shalt. All production to date has been from one level. Because of heavy ground, even on the main haulage horizon, experience has shown that it is necessary to have a minimum cross section in the drifts, thus making it impractical to have a double track system. In 1937, production was 3000 tons per day; in 1938 it was increased to 6000 tons per day and in 1940 to 9000 tons per day. Each increase necessitated a revision in the method of controlling the underground traffic. In 1937 the tramming signal system consisted of a few signal lights in the main haulage drift. These lights were two 100-watt bulbs in a metal box that had one green and one red lens on each side. The box was mounted on the underside of a drift cap timber and could be seen For a considerable distance. The lights were so arranged that all boxes showed either red or green at the same time and all were controlled by a magnetic contactor at the entrance to each lateral drift. When the lights showed green, the main haulage was clear of traffic and a train could enter it. As the motor entered the main haulage drift, the motorman pulled the cord of the magnetic contactor switch, thus changing all the main haulage lights to red, which indicated that no other train could use the main haulage until the first train had turned into a lateral drift. When a train left the main line, its motorman pulled the cord connected with the magnetic contactors, causing the haulage lights to show green again. This arrangement permitted only one train at a time to use the main haulage and thus limited the number of train trips per shift, but it was satisfactory when the ore handled was only 3000 tons per day. Second SystEM Installed With a gradual increase in production it became necessary to place a train dispatcher in charge of all trains. He controlled their movements orally, giving his orders direct or by mine phone, instructing them where to load, when to leave for the station and when to return. His objective was to group several trains traveling in the same direction. Because of the human element involved, some mistakes were made. The danger of a serious collision was always possible. There was a 90° turn and curve in the underground haulageway, therefore travel in this section was always dangerous if mistakes were made in directing traffic. To protect the train crew, particularly the rear switchman who rode the last car or caboose, a two-way push button and flash-signal system was installed on the

Jan 1, 1946

By Leo F. Reinartz

Part III of a four-part series on the history of steelmaking in the US, describes furnace developments, improvements during the last few decades, and the contribution of the AIME. THE invention of the dolomite machine was a great boon to the open-hearth furnaceman. By speeding up bottom making, it helped to increase tons per hour and decrease cost. The first homemade unit was built and operated before 1925 at the South Side works of Jones & Laughlin Steel Corp., Pittsburgh The first commercial machine, similar to those known today, was built for the Donner Steel Co., Buffalo, N. Y., in 1925. Heavy slab buckstays, 6 in. by 15 in., supplanted lighter I-beam buckstays as furnace framework in the middle 1920's. They greatly improved the rigidity of the furnace binding. Although the first sloping back wall had been in- stalled prior to 1920 on a small basic open-hearth foundry furnace at Columbus, Ohio, the impetus to install such back walls universally in ingots shops came after S. Naismith installed the first one on an open-hearth furnace at Illinois Steel Company's South works in June 1924. Before that event, back- wall life had already been improved somewhat by the use of chrome rock or metal-encased basic brick. Here again, these changes heralded major for- ward steps in furnace design, decreased costs, in- creased production, and improved safety and working conditions on the back standing of the furnace. Fuels Up to 1930, a number of different kinds of fuel were used to melt and refine steel in American open hearth furnaces. During World War I, powdered coal was used in a few plants as an open-hearth fuel, but because of the high sulfur and ash content in the coals, many operational difficulties arose. There were also dust, explosion, and accident hazards, so that after the War its use was discontinued. In some steel-manufacturing centers, natural gas was available as a fuel and gave good performance. In most steel-manufacturing centers, operators had to rely on producer gas made from bituminous coals in producer gas houses. Low-sulfur low-ash, high-fusion coals required for the manufacture of such gas were not readily available. The quality of producer gas was uncertain. The gas had to be pre-heated. Maintenance problems connected with the use of this fuel were serious. Tons per hour per month was unsatisfactory. Although petroleum had been first discovered by Edwin L. Drake at Titusville, Pa., in 1859, it was not until the early 1930's that heavy fuel oil residues for open-hearth use began to appear on the market. They were cheap; the calorific value was high, and it was not necessary to pass this fuel through the checkers to preheat it. Various plants began to use such oil as an open-hearth fuel. Others used it in combinations with tar, coke-oven, and/or blast-furnace gases. Because of its low calorific value, blast-furnace gas had to be preheated in the checkers. These fuels were cleaner and more dependable than producer gas. The dirty gas house adjacent to the open-hearth shop was no longer needed, and

Jan 1, 1961

James DouGlas, New York, N. Y. (communication to the Secretary*):—In my paper on the Conservation of Natural Resources, I referred to the slow replacement of bee-hive ovens by the by-product ovens as a most notable instance of waste. And I quoted from Mr. Parker's report for 1906 an explanation given by him in accounting for the small production of by-product coke. It was that the market for the by-products of the coke-ovens was so limited that some of the ovens constructed were out of operation. His report on the manufacture of coke in 1908' does not record an improvement, and attributes the strange fact that we alone, of all the industrial peoples, delay the adoption of this cardinal improvement from the continuance of the same almost inexplicable cause. To quote again from his report, he says (p. 241): "The year 1908 was not marked by any notable gain in the construction of byproduct coking plants, though some new work was done. There was a net increase

Jan 1, 1910

By Edwin Ludlow

THERE has been so much misinformation sent out through the newspapers, and I find so few people who are really acquainted with the true facts in regard to the coal strike, that I feel it would be advan-tageous to present the facts as I have been able to gather them. One of the great points that the miners are now mak-ing is the fact that the operators of the central competi-tive field, consisting of the states of Illinois, Indiana, Ohio and Pennsylvania, have refused to meet them in a joint conference such as has been customary in previous years. There are two reasons why the operators de-clined to hold such a meeting. In the first place, the last time they held a meeting of this kind they were all indicted under the Sherman Act for making an agree-ment in restraint of trade. In the second place, the miners at their convention did not authorize their dele-gates to negotiate a new contract, but instructed them that nothing less than a scale based on the present wage, with the addition that there should be a six-hour day, a five-clay week, time j and a half for over time, and double time for Sundays, would be accepted. These additions would very much increase the cost of coal over the present wage scale. The operators could not consider renewing a contract on the present scale, as it would mean ruin for them, and as the miners were not authorized to negotiate a new scale on a fair basis that would enable the operators to mine coal in competi¬tion, with the open-shop mines the operators did not feel that there was any use in meeting the delegates. Thirty per cent. of the output of bituminous coal comes from the open-shop mines of West Virginia, Alabama and Pennsylvania. During the strike, in 1919, this 30 per cent. was increased to 50 per cent. and it has affected the operations of the union mines to such an extent this year that they have been able to run only 15 to 30 per cent. of their time, while the open shop mines have run from 60 to 80 per cent. as the wages in these mines had been reduced to the 1917 scale.

Jan 5, 1922

By E. G. Leonardon

The object of this paper is to describe briefly the practical results obtained in several problems of civil engineering by resistivity measurements of the underground. It is intended for the mining engineer, as well as for the construction engineer; the stratigraphical problems discussed are general and frequently are encountered in mining exploration. Resistivity measurements have been used in mining and oil exploration for a number of years.' Their introduction in the field of civil engineering, on the contrary, is rather recent. It was applied for the first time in the spring of 1928 near Littleton, N. H., in the survey of two dam sites for the New England Power Assn.2 Since then, the geophysical firm with which the author is connected has had an opportunity to develop this field of activity, and more than 20 investigations at dam and tunnel sites have been carried out in the United States and Canada. A part of this work has been verified by underground or drilling exploration. This paper deals with but a few of the results, which we are permitted to make public now. The theoretical and technical sides of the processes employed will not be discussed; they have already been described in various technical publications. A few general points will be mentioned, to make clear the practical examples given. Resistivities OF the Rocks The surveys are based on the measurement of the specific resistance of the rocks. This resistivity is the electrical resistance of a cylinder of

Jan 1, 1932

By S. W. Churchill

A digital computer was used to obtain an exact numerical solution for the transient behavior of the insulation and earth adjacent to an isothermal, submerged flat surface for a single set of parametric values. Comparison of the computed results with analytical solutions for limiting conditions revealed that a complete and general solution for all parametric values could be constructed from these limiting solutions. Complete and general solutions for insulated spheres and cylinders can also be constructed from limiting solutions. The procedure is illustrated in part for an insulated spherical tank. The heat flow was found to fall rapidly to a pseudo-steady state; after some time, it then decreased slowly to zero for a flat plate and cylinder, and to a low steady-state rate for a sphere. The accumulative heat flow during the initial falling-rate period may be a significant fraction of the heat flow during the entire first year. INTRODUCTION Underground storage of liquefied natural gas and liquefied petroleum gas has received considerable recent attention. The rate of heat flow from the earth to the storage cavity and the resulting temperature field in the earth are important factors in the technical and economic evaluation of such storage facilities. The objective of this paper is to indicate how complete solutions can be developed for the transient flux and temperature field for various geometrical configurations. The representative properties and dimensions, and the resulting parameters utilized in the illustrative results, are indicated in Table 1. The results presented herein are for dry earth. The effect of the latent heat of solidification of water in the soiI will be described in a subsequent paper. The temperature field in the insulation and earth is determined by energy balances, boundary conditions and initial conditions. The physical problem can be described mathematically with virtually no idealizations insofar as physical properties are known. It appears possible to solve the equations by numerical integration on a high-speed digital computer for any geometrical configuration and conditions. For complex situations, however, the computations are expensive and the results are highly specific. Analytical solutions have been developed for a few simple but important geometrical configurations and conditions, including one-dimensional heat transfer from (or to) earth at an initially uniform temperature to (or from) flat plates, spheres and circular cylinders. The solution for an insulated flat plate has also been derived but is in the form of a slowly converging series involving taklated functions. It was planned to use a computing machine to evaluate this series for a number of representative conditions. However, upon examination of the results of preliminary computations it was discovered that a complete, general and accurate solution could be developed by interpolation between several much simpler solutions for limiting conditions. This technique then was used to develop a a complete solution for an insulated sphere. The equations presented herein are derived in Carslaw and Jaegerl and other books on applied mathematics, or they are simple extensions of these previous results. Hence, all derivations are omitted. Emphasis is instead placed on the results and their

By I. S. Servi, N. F. Graves

THE etch-pit technique has long been used to reveal low-angle boundaries and, in general, the distribution of dislocations in high-purity metals. Often this technique is amenable to quantitative computations,' but generally is affected by some degree of uncertainty because etch pits can be nucleated not only by dislocations, but also by inclusions and surface imperfections. In the case of high-purity zinc, Gilman' reported that etch pits were produced only after adding 0.1 atomic per cent of cadmium to the crystals and aging at a proper temperature. In the course of a study of low-angle boundary behavior in zinc crystals, etch pits were produced in 99.999 pct zinc without resorting to intentional contamination, by etching in a 50:50 HNO3H2O solution. The technique consists of etching until the heat of reaction brings the solution to a boil, and in displacing the etchant rapidly with a stream of cold water, thus avoiding staining. The undesirable features of this technique are the heating effect and the removal of a considerable amount of material. A high polish is obtained if staining is controlled properly; therefore, the etch pits appear very clearly and with excellent contrast when observed under dark field illumination. This is especially helpful for cursory examinations at low magnifications. Several observations were made on zinc crystals of square cross section, having one face parallel to the basal plane and one edge parallel to a slip direction, Fig. l(a). When such a crystal was bent about 2" over a glass die and annealed at 390°C, a sharp boundary was formed only in the inner portion of the crystal. Near the two prismatic faces, perpendicular to the basal plane, the boundary was always branched into many lower-angle boundaries, Fig. 1(b). Attempts to move the main boundary by applying a shear stress to the specimen invariably resulted in curving the boundary, the branched ends remaining pinned in their original location, Fig. 1 (c). The prismatic face, when etched as indicated in the foregoing, revealed the existence of numerous (sometimes up to 30) fine boundaries, nearly parallel to each other. Pre-existing lineage boundaries, generally parallel to the direction of growth, were barriers to the formation of polygonization boundaries and interrupted the continuity of the substructure, Fig. 2. Twin

Jan 1, 1959

By Walter Renton Ingalls

Metallurgical literature has no record of any ore beneficiated for cadmium alone, and the cadmium of commerce is derived from zinc ore, with which cadmium is generally associated. Zinc ores free from cadmium—e.g., the ores of the Franklin and Stirling mines, New Jersey, and of Broken Hill in Rhodesia—are rare. Blende concentrates of 50 to 60 per cent grade have contained (in production of important tonnage) as much as I per cent Cd, which is unusually high. The concentrates from the Tri-State district average from 0.3 to 0.4 per cent Cd, which is high. The concentrates from mines west of the Rocky Mountains seldom are higher than 0.2 per cent. In the periodic system of the elements, cadmium is in the same group with zinc. Its properties and compounds are similar. Its metallurgy is also similar. Cadmium has a melting point of 320°C. and a boiling point of 778"C., while the melting point of zinc is 415'C. and the boiling point gos°C. These conditions, together with the lower reduction temperature of cadmium oxide, indicate means for. separating cadmium from zinc. Cadmium in spelter is viewed, if not as an impurity, at least as an alloying element that may be objectionable, its special effect being hardening. However, for some purposes, a little cadmium in spelter is desired, and 0.4 per cent may be permissible, even in spelter for rolling. Cadmium in spelter for brassmaking is completely volatilized at the temperature of that process, and in bygone days an immense quantity of cadmium must have been lost in the fumes from these furnaces. Pyrometalltjrgy—Early Cadmium compounds, sulphide and oxide, being more volatile than the corresponding compounds of zinc, loss of cadmium begins to occur from the first furnace operation. In normal roasting, even with Tri-State ore, this loss may not be very high. Raw ore, assaying 0.4 per cent Cd, may be expected to give a roasted product of the same assay, which would imply a cadmium loss of about 15 per cent. Roasted ore, assaying 0.4 per cent Cd when distilled at ordinary furnace temperature, yielded spelter containing about half of that in the ore charged. The first draw of spelter under these conditions may assay 0.8 per cent Cd (accounting for 22 per cent of the cadmium recovery) and after the several draws of spelter have been equalized the cadmium content may average 0.35 per cent. If, therefore, 2000 lb. of blende averaging 0.35 to 0.4 per cent Cd is roasted and distilled, there may be obtained 1000 lb. of spelter, assaying 0.35 per cent Cd or 3.5 lb. content, which entering into Prime Western spelter will be sold at the spelter price. It will be observed from the outline hereinbefore (summarizing conditions prior to the introduction of sintering) that the main loss of cadmium occurred in the distillation process and by failure to condense, which could be ameliorated by attaching a prolong to the condenser, thus collecting

Jan 1, 1944

By Tell Ertl

The term oil shale is defined. Foreign oil-shale developments are outlined briefly. The richest and most extensive oil-shale deposits in the United States lie in western Colorado. The Bureau of Mines is opening two adjacent areas for underground mining. in western Colorado. From the first area the oil shale is mined selectively as required by the retorting plant. The second area is being developed as a unit of a full scale oil-shale mine to ascertain the most practical methods of mining oil shale and to determine costs. In both of these mining areas, research will be carried on to develop new and improved practices for mining oil shale. Introduction Oil shale is a sedimentary rock containing a solid mineraloid of indefinite composition known as kerogen. On heating oil shale, the kerogen undergoes thermal decomposition and some of the vapor products of the decomposition can be condensed as shale oil. Oil from shale can be a major source of liquid fuels since extensive deposits of oil shale are known to exist throughout the world. The United States considers the establishment of an oil-shale industry only when doubt exists of the adequacy of the domestic supply of crude petroleum. On the other hand, oil shale is not strange to foreign oil men. The industry is an old one in other parts of the world. The French industry has been in existence since 1838, the Scottish since 1859, the Australian since 1860, the Estonian and Swedish The since World War 1, and the Manchurian industry since 1929. The most highly exploited oil-shale deposits are the Carboniferous shales of Scotland. About 20 seams ranging from 4 to I2 ft in thickness are worked. The yield during recent years in scotland has been 18 to 25 gal of shale oil per ton, from 3&"30'000 tons per year' The French and Swedish oil-shale deposits are of lower grade than the Scottish. The Estonian oil-shale deposits are 7 ft thick, and the oil yield averages 50 gal per ton. Over 1,000,-ooo tons are mined each year, half of which is used directly as fuel to substitute for coal and the other half is used for the production of oil. Immense deposits of oil shale that will yield 10 to 15 gal per ton exist in Germany. Because of the impending loss of the Rumanian and Polish oil fields and the bombing of synthetic liquid fuel plants, the Nazis in 1943 started a large-scale oil-shale program in Germany. By V-E Day, it is said, oil-shale production had reached the rate of 2500 tons per day and rapid expansion of the industry was imminent. Australian oil shale, known as torbanite, occurs in beds 2 to 6 ft thick. It is of a very high grade and on retorting yields 80 to 160 gal per ton. The oil-shale industry of Manchuria was the largest in the world during the past decade. The well-known Fushun coal deposit in Manchuria has an overburden of 500 million tons of oil shale about 450 ft thick that will yield 10 to 15 gal of shale oil per ton. The oil shale is

Jan 1, 1949

By M. J. Sinnot, J. C. Shyne

Low-frequency mechanical damping measurements were made to investigate internal friction in Fe-A1 alloys. The atomic ordering of the Fe-A1 system strongly influenced the stress-induced ordering internal friction. Magnetoelastic damping was also encounteyed and was shown to be reduced by the application of a static stress. THIS paper describes some damping experiments made on alloys of Fe and Al. Stress-induced ordering internal friction was measured with samples containing from 9.8 to 31.3 at. pct Al. Aluminum is soluble in a-Fe to about 50 at. pct and forms at least two long-range ordered structures, Fe3Al and Feu.' Stress-induced ordering internal friction is known to occur in many substitutional solid solutions, but few measurements of this damping effect have been made with alloy systems that have pronounced ordering tendencies. LeClair and Lomer developed expressions relating the relaxation strength of the damping process to the degree of atomic ordering and predicted that stress-induced ordering internal friction would be zero with complete ordering.' This concept was confirmed experimentally by Lulay and Wert using the system cd-Mg It is also consistent with the weak stress-induced ordering peaks observed in P -brass by Artman and in 16 wt pct Al Fe-Al by bert.' It was expected, therefore that the ordering characteristics of the system Fe-Al would strongly influence the stress-induced ordering internal friction exhibited by the experimental alloys. SAMPLE PREPARATION The alloys used in this investigation were induction melted under vacuum using high-purity melting stock. The iron was electrolytically refined Plastiron 101 which contained 99.85 wt pct Fe. The aluminum was a special 99.95 pct pure grade supplied by Alcoa. The only other raw material was spectrographically pure graphite which was used in small quantities as a deoxidant. The amount of carbon used was slightly in excess of the amount required to completely deoxidize the melt; this resulted in residual carbon contents of 0.01 to 0.02 pct in the finished alloys. The vacuum cast 2 1/2-in. diam ingots were hot rolled to 5/8-in. diam round bars. Portions of these bars were hot swaged and hot drawn to 0.050-in. diam wire. Straight pieces of the hot drawn wire were slowly heated to a temperature of 1300°C in a He atmosphere. After holding for 4 hr, the samples were allowed to cool in the furnace. This annealing treatment resulted in grain growth in the samples, the final grain size being about the same as the wire diameter. The grain boundaries were oriented perpendicularly to the wire axis, giving a bamboo grain structure. The existence of a preferred orientation could not be detected in these coarse grained samples. If the samples had a fiber structure, this probably would have been the same in all samples because of similar processing, thus the influence of crystal orientation on the relaxation strength would have been similar in all samples. The aluminum contents of the alloys are listed in Table I. EQUIPMENT The principle of the torsion pendulum was used for the internal friction measuring device. The

Jan 1, 1961

By Charles H. Mitchell

British Columbia is enjoying a period of sustained high-level activity in all aspects and sectors of its mining industry. The total value of mineral production for 1962 was in excess of $229 million. This was the greatest total value attained for any year to date, exceeding the previous record year of 1956 by more than $40 million. It appears reasonable to expect that value of production for 1963, stimulated by increased production attained during the year, and by improved metal prices for some of the major products, will be substantially in excess of that recorded for 1962. Elsewhere in this issue appears a detailed report of prospecting and exploration activity in the Province. For the purposes of this review it is sufficient to state that the level of prospecting and exploration activity during the past several years has been greater than at any previous time and that there does not appear to be any slackening in activity or interest.

Jan 12, 1963

By F. B. Sherman, Keros Cartwright

Sanitary land filling has become one of the most widely used methods of disposing of solid refuse. A principal concern of regulatory agencies and the public itself is that landfill operations do not degrade the physical environment, including water resources, and the ground-water reservoir in particular. Knowledge of ground-water and engineering geology can guide landfill operations into suitable terranes or develop measures to compensate for natural limitations at a particular site. Experience and research in Illinois suggest four activities relating to landfill disposal that warrant attention by geologists and engineers: (1) regional delineation of favorable and unfavorable hydrogeologic conditions to facilitate planning and preliminary screening of potential landfill sites; (2) site evaluations, with considerations of geologic materials, topography, water levels, flow systems, and local occurrence and use of water resources; (3) research on aspects of the hydrogeologic environment that control effects of, or are modified by, landfills; and (4) formulation of practices in the siting, construction, and operation of landfills that prevent, mitigate, or isolate deleterious effects. The first two activities are basically in the domain of earth science, requiring the application of fundamental concepts of geology and hydrology and conventional site-exploration methods. The third activity, research, requires contributions from geology as well as other disciplines, including soil physics, sanitary engineering, and chemistry. The fourth calls for policy decisions by regulatory agencies and elected officials, using the contributions of scientists and engineers. Throughout history, man has disposed of unwanted materials by dumping. As urbanization has increased, haphazard dumping practices have given way to disposal under more controlled conditions because of increasing congestion of population and production of waste and greater concern for public health and environmental amenities. Many states and communities have already outlawed open dumping and open burning of refuse. The only practical methods of disposal of large volumes of refuse, therefore, are contained, high-temperature incineration, or burial in a sanitary landfill. In Illinois, regulation of solid waste disposal has been delegated to the Environmental Protection Agency. Each session of the legislature since 1965 has passed increasingly strict laws regulating waste diposal. As a result, the work of evaluating sanitary landfill sites has increased significantly for both the Department of Public Health, now the Environmental Protection Agency, and the Illinois State Geological Survey, which advises the Agency on matters of ground-water geology and pollution. In fact, our ground-water staff spends as much time on studies relating to waste disposal, primarily sanitary landfills, as on ground-water resource studies. Many other geological agencies are experiencing similar demands for increased assistance in solving waste-disposal problems. This paper summarizes some of the salient features of the sanitary landfill concept, describes activities of the Illinois Geological Survey in ground-water and engineering geology relating to landfills, and suggests policies that need consideration. A sanitary landfill is located and operated in such a way that vermin and pests, nuisances, and degradation of air and water are kept at acceptable levels. Some of the physical requirements of a sanitary landfill are all-weather roads for year-round access, fences to retain blowing paper, a daily cover of at least six inches of suitable earth material, and a final cover of at least 2 ft of earth material. Dumping into or adjacent to standing water generally is not allowed. Two common operating techniques are used. In the first, trenches are dug, the refuse is placed in them, and the earth removed from the trenches is used to cover the waste. In the second method, area fill, refuse is placed in low ground and covered with earth from adjacent high areas. The hydrology of the site is a prime consideration in locating sanitary landfills. Putrescible refuse, if saturated above field capacity, produces a leachate that usually has a high concentration of dissolved solids.2 As the leachate also acts as an agent for transporting bacterial pollutants, it constitutes a potential pollution hazard. To reduce the production of leachates, the topography of the landfill area should be such that surface water will not flow into or through the fill. Operations that will result in refuse disposal below or near the highest known water-table elevation may be required to take corrective or preventive measures to protect the ground water. In practice, under humid conditions such as prevail in Illinois, locations where disposal can take place above the water table are relatively few because surficial materials are commonly fine-grained, which permits slow gravity drainage and results in high degrees of saturation (100% moisture content) near the surface. At some sites, although disposal has taken place above the water table, ground-water mounds have developed, resulting in permanent saturation of the refuse. Permeability barriers usually are required to protect the ground-water reservoir from degradation by leachates. The convention in Illinois is to have a minimum of

Jan 1, 1972

By Ernest Gayford

This is a nontechnical paper on flotation, subdivided under three general headings: (I) Definition of flotation; (2) what flotation is now doing in Utah; and (3) what is the future of flotation? Definition T. A. Rickard defines flotation' as "the act or state of floating," from the French flottaison, water-line and flotter, to float. The dictionary defines flotation as "the science of floating bodies." The flotation process is a method of concentrating ores by frothing. Weinig and Palmer,2 define flotation as follows: What is the flotation process? Briefly, it consists in the agitation of finely divided ore in water containing bubbles of air or gas, a small amount of oil and, usually, other reagents, soluble and insoluble; under these conditions the small particles of native metals, sulfides, arsenides, antimonides, selenides and tellurides show a tendency to attach themselves to the films of the bubbles, and are thus carried to the surface of the water. The oxidized gangue minerals, such as quartz, feldspar, limestone, hematite, etc., show much less affinity for the bubbles, are easily wetted by the water, and either remain in suspension in the water, or sink to the bottom of the vessel. If the bubbles are sufficiently stable they can be removed, carrying their load of sulfide-mineral particles with them. Thus there can be effected a separation of the two classes of minerals from each other, assuming that the grinding has been sufficient to unlock all of the particles of different composition. The separation does not depend upon differences in specific gravity of the various minerals; in fact, the sulfides are usually heavier than the oxides, and some of the heaviest sulfide minerals are the easiest to float. A particle of mineral may be so large, however, that its weight will counteract its affinity for the film of the bubble. In most cases the ore must be fine enough to pass a screen having at least 48 meshes to the linear inch. Taggart3 defines flotation as follows: Flotation is a method of wet concentration of ores in which separation of mineral from gangue is effected by causing the mineral to float at or above the surface of a body of liquid pulp while the gangue becomes or remains submerged. The method

Jan 1, 1928

By Ernest Gayford

THIS is a nontechnical paper on flotation, subdivided under three general headings: (1) Definition of flotation; (2) what flotation is now doing in Utah; and (3) what is the future of flotation? . DEFINITION T. A. Rickard defines flotation1 as "the act or state of floating," from the French flottaison, water-line and fitter, to float. The dictionary defines flotation as "the science of floating bodies." The flotation process is a method of concentrating ores by frothing. Weinig and Palmer 2 define flotation as follows: What is the flotation process? Briefly, it consists in the agitation of finely divided ore in water containing bubbles of air or gas, a small amount of oil and, usually, other reagents, soluble and insoluble; under these conditions the small parti- cles of native metals, sulfides, arsenides, antimonides, selenides and tellurides show a tendency to attach themselves to the 6lms of the bubbles, and are thus carried to the surface of the water. The oxidized gangue minerals, such as quartz, feldspar, limestone, hematite, etc., show much less affinity for the bubbles, are easily wetted by the water, and either remain in suspension in the water, or sink to the bottom of the vessel. If the bubbles are sufficiently stable they can be removed, carrying their load of sulfide-mineral particles with them. Thus there can be effected a separation of the two classes of minerals from each other, assuming that the grinding has been sufficient to unlock all of the particles of different composition. The separation does not depend upon differences in specific gravity of the various minerals; in fact, the sulfides are usually heavier than the oxides, and some of the heaviest sulfide minerals are the easiest to float. A particle of mineral may be so large, however, that its weight will counteract its affinity for the film of the bubble. In most cases the ore must be fine enough to pass a screen having at least 48 meshes to the linear inch. Taggart defines flotation as follows : Flotation is a method of wet concentration of ores in which separation of mineral from gangue is effected by causing the mineral to float at or above the surface of a body of liquid pulp while the gangue becomes or remains submerged. The method

Jan 1, 1928

By S. P. Kinney, A. J. Boynton

THIS paper is not the result of recent research with regard to any particular feature of iron metallurgy, blast-furnace practice or mechanical engineering. It is rather a series of notes with regard to contemporaneous progress in blast-furnace construction and operation, together with some suggestions as to changes and improvements that seem to be desirable. On April 1, 1930, a committee of the Chicago District Blast Furnace and Coke Association presented to that association a rather ambitious study of blast-furnace equipment, together with recommendations for the design of construction of a complete blast-furnace unit for the production of 1000 tons of pig iron per day. This report represented the result of months of study by members of the committee, all of whom were actively engaged in operation or design of blast-furnace plants. It is natural, therefore, that comments on the present state of the art should take this 1000-tons furnace, as recommended by the Association, as a basis for comparison with corresponding features of construction or design. See Table 1. In looking through this report at the present time, the significant difference is in the nature of the gas-washing equipment that today would be specified. In other respects, the installation would remain generally very much as it was outlined in 1930. The change in furnace dimensions would be very slight and of no especial significance, except with respect to changes in stock-line diameter, of which more will be said hereafter. The high-efficiency stove as developed by various designers is thoroughly described within this report, and few changes have taken place since. Blowing equipment shows refinement and reflects the improvement in steam engineering. Hoisting and charging equipment and ladles for the conveyance of iron and slag remain, in general, as they were in 1930. In accordance with a general tendency

Jan 1, 1935

By Gloyd M. Wiles

Since D. C. Jackling was famous for his adeptness at organizing and training teams of operating personnel, the subject of mine management is particularly appropriate for a Jackling Lecture. In fact, it is doubly appropriate because in very basic ways Jackling's career changed the nature of the tasks and challenges facing a mine manager. Management of mines, of course, is the art of finding and winning minerals economically from the earth's crust, and it involves the use of all the engineering sciences. But also of prime importance is a skill which is not yet a science-the area of management often referred to as human engineering. Since expenditures on staff and labor may well involve more than 50% of the direct costs of operating a mine, ability at human engineering is just as important as the ability to plan and put into effect the most efficient operating procedures.

Jan 5, 1962

By D. R. Mitchell

MEETING for the thirteenth time in New York as part of the five-ring circus known as the Annual Meeting A.I.M.E., the Coal Division experienced a wartime boom in attendance. Technical sessions were crowded and whereas 65 seats were set up for the annual luncheon meeting of the Division over 100 members showed up, many of whom had to be fed elsewhere. Possibly the Coal Division should adopt "13" as its lucky number. Discussions at technical sessions, formal and informal, were lively. Those papers containing material directly concerned with the war, or containing information that might be usable for war industries, were enthusiastically received. Some criticism was made in regard to the present method of handling discussions and it was suggested that better success would be had in getting discussions in the record by the use of hired reporters. This is being considered by the executive committee of the Coal Division.

Jan 1, 1943

The Sub-committee on Coal Mining, since its appointment, has been collecting data about subsidences in coal mines in this country, and thinks that almost all of the available data about occurrences of this sort in bituminous mines has been collected. Similar data is being compiled for the anthracite regions, which it is hoped will be ready for the 1927 meeting. As most of the bituminous seams are nearly level, the records obtained give the problem in its simplest form, without complications due to the pitch of the seam. Copies of the questionnaire, Appendix A, were mailed to all of the coal operators' associations, to most of the large operating companies and to many engineers, with the request that any data on the subject be returned to the committee, or that advice of any subsidences known be given: the replies to most of the questionnaires were general, although some specific cases were given. Many of the companies were unable to reply to all questions, as they lacked the necessary data, but in nearly every case where accuratc data was available, it was cheerfully furnished, and any additional information requested was secured. All specific cases of subsidence were followed up by correspondence, and in several cases by personal inspection. Figs. 1 to 31 were made from the information furnished. Table 1 gives measurements of elevations taken in one case at intervals from October, 1913, to May, 1918. With one exception, where the evidence cannot be released on account of a lawsuit, it is believed that the cases submitted with this report include practically all that have happened in bituminous coal mining in this country of which actual measurements were secured. Some of these have been published by Young and Stoek,l and some have been secured from other publications. In collecting these data, the subcommittee had the Engineering Societies Library extend its bibliography to date; this list is given in Appendix B. To assist in the study of the problem, all of the subsidence literature in English was examined for cases in which spccific measurements were given, and the essential data for each case are shown in Appendix C.

Jan 1, 1927

By Rudolph G. Wuerker

Charles T. Holland (Head, Dept. of Mining Engineeri*, Virginia Polytechnical Inst., Blacksburg, Va.) Mr. Wuerker has presented a very interesting discussion of the use of triaxial test methods for investigating the strength properties of rocks. Such methods, no doubt, eventually will develop considerable information of interest to those concerned with the design of mine layouts, particularly in the field of pillar design. From his discussion of my recent article, "Cause and Occurrence of Coal Mine Bumps" (Holland Mining Engineering 1958, p. 933-1002), it is evident that in one place at least I did not make my meaning clear to him and perhaps others. To clear the matter up I think it best to quote from the article, somewhat more fully than did Mr. Wuerker, as follows: "4) In actual operations — because rocksare not perfectly elastic, homogeneous, nor isotropic and because local yield does occur — the maximum stress as demonstrated by Phillips (Ref. 22, pp. 64, 65) and indicated by much experience in mining, does not occur at the walls of the opening but at a short distance inside the pillar. Furthermore, the maximum stress does not reach as great a value as theoretical considerations and laboratory experimental methods indicate.* Actual distance inside the pillar, measured from the wall, at which the maximum stress exists, has not been determined. Observations in many mines, however, indicate that this distance could have a mini-value of one to six or eight times the bed thickness and that it is probably affected by width and height of the opening, depth of cover, and relative values of the elasticity and plasticity of materials comprising the roof, floor, and coal seam. The actual value of the stress produced probably lies between the theoretical maximum and the average stress concentration that would be produced if the weight of the strata above the unsupported opening were evenly distributed over the pillars for a distance equal to the opening width." The footnote reference in the above quotation referred to the following: "*For example, the Pocahontas No. 4 coal bed in southern West Virginia is mined under cover up to 1800 ft thick. Development openings are driven 18 to 20 ft wide, and the bed is about 6 ft thick. According to the work of Panek, the tangential wall stress at mid-bed height under these conditions would reach values between 4000 and 5000 psi. Actual tests of 3-in. cubes of this coal show its compressive strength would be much less than this, perhaps as low as 400 psi. Yet the pillars usually show no evidence of failure in these headings. In this same bed at a depth of 800 ft, the author has seen an opening 225 ft between supports lying between two old groves approximately 1100 ft apart. According to the theoretical considerations, the stress in the pillar walls would have been about 18,000 psi, yet the pillar showed little or no evidence of weight. In view of these observations, it is clear that the wall stress does not attain the maximum values indicated by theory." (Underlining added to original wording.) By referring to Fig. 2A of my paper it will be noted that theoretically the maximum pillar stress would occur at the pillar wall, i.e., at the passageway surface of the pillar. Obviously this cannot be correct in the cases of stress ranging from 4000 to 18000 psi since the coal at the surface of the pillar is under no constraint and cannot have a strength much greater than 400 or 500 psi. Hence, my conclusion that the maximum stress does not occur at the wall but back in the pillar some distance from the wall. Since these stresses are pushed back in the pillar from the wall, it is also obvious that the loads transferred to the pillar from the opening will be spread over a greater area and hence Pillar stresses will not rise to the values postulated by theory and photoelastic experiment. Further since to visual inspection the coal along the pillar wall did not appear to be failed the conclusion was reached that the stress shift was caused by local elastic or plastic yield and by difference in the elastic modulus of the rocks composing the mine floor, mine roof, and coal bed. Later on under the heading "Strength of Mine Pillars" (pages 1000-1002) the effects of constraint is briefly described. Also a formula taking into account constraint is developed relating pillar strength to the uniaxial strength of coal and the L/T ratio of the pillar. Since my paper was written, reports of experiments conducted in South Africa (Denkhaus, et. al., 1959), in Sweden (Hast 19581, and in Canada (McInnes, et.al., 1959) reveal that the conclusion expressed relative to the existence of a low stress area existing around the edges of pillars and solid faces as described above is generally correct. But it seems possible that where the wall stress developed is less than the unconfined strength of the rock composing the pillar and where the roof, floor, and pillar

Jan 1, 1961