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By O. W. Walvoord

A Definition: An ore feeder is a mechanical device that, by virtue of its motion, causes ore to be supplied or carried forward at a desired metered rate to other milling equipment. From the viewpoint of economics there can be little question, even for small tonnage operations, as to the advisability of using mechanical feeders in the place of manual labor. Only a few short years ago, it was common practice to employ crusher men for the feeding of crushers, thus eliminating the capital expenditures required for mechanical feeding equipment. Having been a crusher man in several instances, the author does not favor such practice. The high cost of labor today eliminates the crusher man, and feeders become an economical capital expenditure when considered against the importance of obtaining maximum production efficiency from all the machines in a process flowsheet.

Jan 2, 1955

ION exchange is one of hydrometallurgy's new tools, new in application, vet old in principle. Cation exchange between solution and a solid exchanger has been known for more than a century, but ion exchange is still in its infancy for metallurgical use. Still hampered by cost of media, it is faced with much development of actual physical handling. Growing consumption of the rarer metals and need to treat leaner ores are pushing extractive methods ahead. Public concern with stream pollution, or legal requirements, are forcing a clean-up of waste discharge. Industries are finding it vital to make some recovery from heretofore waste material to help pay costs of discharge treatment.

Jan 5, 1953

By Harry Tufft

FOR many years the treatment of mine timbers with preservatives was confined to a few pioneer plants in the United States, and it is only in the past few years that the practice has grown appreciably. In a field study of the mine timber situation in Illinois, Pennsylvania, and further study of the situation in the country as a whole, I found that most mine operators did not keep records on mine timber that would afford the necessary data for determining the possible savings from preservative treatment. Some primary questions the mining engineer should be able to answer before making his decision on preservative treatment. for a particular mine are: (1) Quantity and cost of timber going into permanent workings annually; (2) quantity and cost of annual replacements due to decay; (3) life of untreated timber in different places; (4) desired life of timber. With the necessary facts in hand, he can then con-fidently select a method of treatment and preservative that is best suited to his needs. In former years when timber was cheap and an abundant supply could be had close at hand, as was the case in the majority of mining regions, the mine op-erator did not concern himself much except to see that enough was supplied to keep the workings safe. The cost figure for timber and labor, distributed to cost per ton of ore, was all the bookkeeping necessary. With present costs of timber, labor, and increasing length of haul to the mine, many operators are paying closer attention to timbering costs and studying them in. more detail. Some of the larger and more progressive opera-tions now keep detailed' figures that give information on all phases of their timber problems. However, at the majority of mines the data available do not permit such analysis. Checks as to where the different con-signments are placed, the date of setting, and the period

Jan 6, 1927

By C. T. Van Winkle

MINE fires are always dangerous and are frequently accompanied by loss of life during the period of confusion which is apt to follow their discovery. In metal mines, fires may result from the accidental ignition of some combustible material, or they may be of spontaneous origin resulting from the rapid decomposition of sulphide. They occur frequently enough to demonstrate the need of some special equipment and a general plan for controlling them, in addition to measures for their prevention. Nearly all the large copper mines have had fires, and the methods of fighting them have been well described in recent papers, notably-by C. L. Berrien,1 R.. E. Tally,2 and others in discussion. The Copper Queen mine has many shafts, which are connected by underground workings. The deeper parts are ventilated by fans, but in the shallower portions natural ventilation through numerous connecting raises or shafts is sufficient. There have been several fires in the past few years, of which all are extinguished but one, and that is under control. These notes cover particularly the preparations that are being made-to check a new fire, partially or temporarily, and to facilitate the escape of workmen in the interval before a definite plan of fighting it can be established. A fire may occur in a shaft or station, or in some working father away. In case of fire in an upcast shaft, the gas would escape to the surface and the immediate result would probably not be dangerous to workmen, as they could escape by other shafts. In a downcast shaft, however, the gas would be distributed very rapidly throughout a large portion of the mine, and men might easily be trapped and asphyxiated. A fire in mine workings, drift, raise, or stope, would be dangerous in a degree, but the draft there is likely to be less strong than in a shaft and probably a smaller area would be invaded by the fire gases.

Jan 1, 1918

By A. B. Kinzel

SINCE the exposition of the behavior of certain iron alloys by Sykes1 involving the existence of an austenite loop and the discovery of such a loop in the chrome iron system by Bain,2 there has been much conjecture both on his part and on the part of metallurgists in general as to the exact shape and location of this loop. In previous work commercial steel has been used and the microscope has been employed to locate the critical points so that the position of the loop has been quite approximate. Numerous attempts have been made to measure the critical points of the carbon-free alloys but all of these for one reason or another have failed. A satisfactory method for studying these phenomena, is presented here. MATERIAL The first difficulty in this study was to obtain pure chromium-iron alloys. This has been overcome by melting in a vacuum electrolytic iron and chromium analyzing 99.84 Cr, Fe and C. A pure magnesite crucible was used and the melt allowed to solidify in the crucible. A typical analysis is chromium, 10.10 per cent., carbon, 0.006 per cent., silicon and manganese nil. To overcome the problem presented by segregation, ingots were made into wire 0.04 in. in diameter. This was accomplished by hand-forging the ingots into rods, using an oxyhydrogen flame for heating, in order to avoid carbon. Subsequently the rods were swaged too wire, the heating being carried out in hydrogen. Thus local segregation was eliminated although differences in analysis between portions 50 ft. apart were noted. An electric-resistance method was first tried to determine the critical points, but due to the physical defects in the wire this failed. Bain had previously shown the presence or absence of critical points in a qualitative way by observing the sag in a catenary. The author has devised the following method which gives an accurate determination of the critical points from expansion-temperature curves of suspended wire, a special telescopic dilatometer being used for the purpose.

Jan 1, 1928

By John B. Gustavson, Thornton L. Neathery

A geochemical survey was conducted in the gold district in Alabama. Eight old mines were found to be sufficiently large in tenor and tonnage to be economical today. Four of these appeared to be amenable to exploration for new blind deposits. A gaseous aspiration AA method was used on soil samples. The results indicate that arsenic, antimony, and zinc may be good pathfinders for lode gold and residual placers in the saprolite. Antimony and zinc display a high correlation coefficient at gold-bearing locations in contrast to non-mineralized areas. The low cost of this method could make it a tool for selecting detailed targets to be drilled and trenched in the saprolite. Outcrop sampling was found to be inefficient due to paucity of outcrops and lack of correlation between the trace elements and gold in the rock samples, due to extensive weathering. Schistosity changes and silicification, on the other hand, have been found to be helpful in exploration around granite plutons.

Jan 1, 1977

By R. C. Palmer

THE testing of flotation oils has occupied a large part of the time of the testing departments of various companies using the flotation process in the beneficiation of their ores. The great differences in ores and iii oils has made such work necessary as it has not been possible to select the oil best suited for the purpose without trial of many kinds. In fact, individual shipments of flotation oils from the same manufacturer will often differ so radically that the mill men have been forced to test every lot of flotation oil before its use in the mills. Further, although almost every imaginable product of the distillation of wood, from alcohol to pitch, has been tested in a more or less perfunctory manner by various people, few companies have allowed the results of their tests to be made public. This work was undertaken for the purpose of obtaining reliable data regarding the value as flotation agents of a number of products that are obtained from the distillation of wood by different methods, and incidentally to determine whether some of the products not used at present could be used. Large quantities of such materials are being wasted or burned in the wood-distillation plants of the United States, and if some use other than fuel could be found for these materials, such a use would represent a distinct saving to the country as a whole, would increase the profit of wood-distilling plants now operating and perhaps make it possible for others to operate which at present cannot do so except at a loss. At the same time it was thought that if such products can be used as flotation agents, then their use would serve to increase the number of oils and other products available for flotation purposes. It was also hoped that it might be possible to discover a substitute for some of the most effective but comparatively high-priced oils which are now used for flotation

Jan 8, 1916

RECENTLY, we were asked to name the greatest contribution to progress in mining technology during the past 25 years. Immediately, the introduction of the pneumatic hammer for making blastholes came to mind because it can be credited with speeding the excavation of rock and the elimination of hand drilling. Possibly this answer was so spontaneous because we were working on this "drilling issue" Of MINING ENGINEERING. Present drilling tools have devel¬oped so rapidly, that a great deal of engineering is. required in the selection of bits, steel, and machines for the drilling conditions at each mine. Formerly a modicum of engineering was utilized in selection of equipment for it was purchased from manufacturer preference. With the development of alloy drill steels, tungsten-carbide bits, throwaway bits, and the jackleg drill, mining companies began doing more experimental work before making selections. It is unfortunately true, that each operator must begin at the beginning by doing his own test work before choosing his drilling method, and tools. Some of this work has been done very well-under controlled conditions and obtaining proper data on the variables. Such data should be accumulated from the various mines, tabulated, and published. Such a volume would be of tremendous help to the small operator in selecting equipment and would permit the research departments of the larger companies to formulate some measure of rock drillability and to undertake more specialized research on the different phases of drilling.

Jan 1, 1952

By Zay Jeffries

Discussion of the paper of ZAY JEFFRIES, A. H. KLINE and E. B. ZIMMER, presented at the New York meeting, February, 1916, and printed in Bulletin No. 108, December, 1915, pp. 2359 to 2369. ZAY JEFFRIES, Cleveland, Ohio.-The original portion of this paper represents a laboratory method for determining grain size in metals. It was developed not so much to find a quick method as it was to facilitate certain work which I was carrying on a couple of years ago. I had a great many determinations to make and the planimeter method was very slow, as was the Heyn method, and both of them were laborious, so I tried to shorten the time of the determinations. Since preparing the present paper, Dr. T. M. Focke, Professor of Mathematics at Case School of Applied Science has called my attention to the fact that both the Heyn and Intercept methods are mathematically

Jan 5, 1916

By J. W. White, J. M. Richardson

Mass balance calculations on industrial grinding circuits are routinely performed during circuit design as well as during post-installation evaluation of operating circuits. Though such routine mass balances are straight- forward, a systematic approach can yield substantial long-term benefits. This chapter presents and evaluates several approaches useful for achieving various circuit design objectives and also considers several methods for reconciliation of data collected around an operating circuit. Numerical examples illustrate the basic concepts and techniques.

Jan 1, 1982

G. A. ROUSH,* South Bethlehem, Pa. (written discussion?).-Mr. Frey is correct in his impression that ice floats, but "frazil" ice happens to be the exception to the rule. The requirements for the formation of

Jan 12, 1919

By C. E. Meissner

THE need for a practical method of deciding upon new alloy steel analyses to widen its markets was the problem facing the Chrome Steel Works at the beginning of 1927. In addition to determining the physical properties of the alloys under consideration, it was necessary to test their value in service. Small melts of steel in a crucible, from which test specimens could be made, were insufficient to determine more than physical properties, therefore actual castings and ingots had to be made before the products could be placed in service. Furthermore, to save further experimental work, it was desirable that these heats should be made on a "pilot" basis; that is, actually duplicating regular open-hearth furnace practice. Therefore a one-ton (2000-lb.) acid open-hearth furnace was built. FURNACE DESIGN There are no special features in the design of this furnace. Standard acid open-hearth practice is followed, with the reproportioning of the dimensions necessitated by its small size; notably, a considerably increased length in proportion to width in order to get proper flame propagation. After the first heat was made it was found that the checkers were insufficient. The checker chambers were increased in size and the checker openings were made much smaller. The furnace was started late in March, 1927, and made 65 heats. Experimental work was then stopped until the data accumulated could be worked up and summarized. The run was resumed in November and the furnace is still operating, having made at this writing 60 additional heats. For the last series of runs, there was some rebuilding of both the furnace itself and the checkers. Slag pockets were added. Fig. 1 shows details of construction; Fig. 2, the, general appearance. All designing was done by the operating and engineering staff. Construction materials were those available around the plant. The reversing valve is a standard butterfly type taken from an old furnace.

Jan 1, 1928

By W. G. Fischer

This paper attempts to close the gap between extensive rock testing with field measurements and the mine operator's need for safe mine layouts and alternatives. It was found that many of the variables that influence mine geometry and worker safety are relatively unimportant while others are critical. The development of empirical relationships that tie the critical variables to the safe useful life of a trona mine layout and observations made in 140 production areas where the variables were researched over a 15-year period are discussed. The concepts presented may have applicability in mine design for other bedded deposits.

Jan 1, 1986

By Karl F. Peterson, H. K. Najarian, Robert E. Lund

PRIMARY products of the Josephtown smelter are zinc metal of various grades, lead-free zinc oxide pigments, cadmium metal, and sulphuric acid. Zinc concentrates of domestic and foreign origin are blended and desulphurized at the roaster plant. The equipment includes five, 12-hearth Herreshoff roasters and two modified Trail-type suspension roasters. The sulphur dioxide containing gases from the roasting operation are diverted to a four-unit contact acid plant for the manufacture of sulphuric acid. The roasted calcines are agglomerated by sintering on Dwight-Lloyd-type sintering machines; the sinter is crushed and sized within required limits; and the sized sinter is smelted in vertical shaft-type electro-thermic furnaces. Of the 13 electrothermic furnaces of various sizes now in operation, four are designed to produce American process zinc oxidc of various specifications; and the remaining nine furnaces are equipped with vacuum-type condensers and produce zinc metal. Papers describing the general smelting practice at Josephtown have been published by AIME. Since both High Grade zinc metal and lead-free zinc oxide pigments are produced direct from the electrothermic furnaces without need for subsequent refining, the elimination of impurities such as lead and cadmium has to be accomplished during roasting and sintering operations. To effect the producing of both High Grade and Prime Western zinc products, the roasting and sintering operations are on two separate circuits. A High Grade circuit produces finished sized sinter low in lead, cadmium, etc., for the High Grade furnaces; and the Prime Western circuit produces finished sinter destined for the furnaces producing Prime Western metal. Sintering at the Josephtown smelter differs in many important respects from the sintering practice in smelters operating horizontal retort zinc furnaces. Requirements of the electrothermic smelting furnaces define the physical characteristics of the sinter, while the chemical composition of the sinter is controlled according to the grade of metal and oxide to be made as final products. Three principal objectives in the sintering process at Josephtown smelter are: 1. To transform the zinc calcine from the roasting operations into a hard, yet porous agglomerate that will not crumble in the smelting furnace. 2. Crushing and sizing of the sinter to obtain a proper screen analysis which is normally —% in. down to +1/4 in. particle size. 3. To eliminate, particularly in the High Grade circuit, as much of the impurities such as sulphur, lead, and cadmium as possible. The sintering plant as originally built in 1930 was equipped with three standard 42 in. x 44 ft Dwight-Lloyd sintering machines. Each machine was equipped with a 15x60 in. sintering corporation fan driven by 150 hp, 900 rpm synchronous motor through a magnetic clutch and capable of delivering 30,000 cfm of air at 15 in. of water and 150°F. Each sintering machine was driven by 7½ hp dc motor with controllers for varying the speed of the machine from 8 to 32 in. per min. The pallets were cast iron and the grates of the herringbone type. The charge was mixed in a 4 ft diam x 8 ft Stehli pugmill and transported by belt conveyor, elevator and tripper conveyor to a small bin over each machine. Shortly after the start of operations the following changes were found necessary: 1. The herringbone grates which plugged very quickly and were difficult to keep clean were replaced by straight, narrow cast-iron grate bars running at right angles to the travel of the pallets. These grate bars are held in place by a center bar extending across the pallet on the 24 in. dimension and by removable retaining plates which form the sides of the pallets. 2. Mechanical grate knockers were developed in conjunction with new grate bars for continuously and automatically cleaning the grates. 3. As the cast-iron pallets cracked, they were replaced with cast-steel pallets. In 1938, the capacity of the sinter plant was increased with the installation of two 42 in. x 22 ft machines which were brought from the company's Herculaneum lead smelter. With a circulating load of some 250 to 300 pct, production of finished sinter on the 42 in. x 44 ft machines at this time amounted to about three tons of sized sinter per machine hour. In 1945, one of the 42 in. x 22 ft machines was replaced by a 60 in. x 44 ft machine of our own design. In 1948, as part of the plant-wide expansion program, the sinter plant not only was expanded but also divided into two separate plants; namely, Prime Western and High Grade circuits. The sinter destined for furnaces producing Prime Western zinc metal is made in a new plant comprising two 60 in. x 44 ft Dwight-Lloyd-type sintering machines, each having a 45,000 cfm Sturtevant fan at 18 in. water static pressure and served by an 8 ft diam x 12 ft long rotary charge pclletizer and auxiliary crushing and sizing equipment. The sinter destined for furnaces producing High Grade zinc metal and zinc oxide pigments is produced in the old sinter plant which was expanded to accommodate four of the 60 in. x 44 ft sintering machines, replacing the old sintering units. In the High Grade sinter circuit, two units of the 60 in. x 44 ft machines are used as preliminary soft sinter machines; and the remaining two units of the 60 in. x 44 ft machines are used to make finished hard sinter. Purification Theory Partial elimination of lead and cadmium in the sintering of zinc ores is common knowledge. However, by some manipulation and by taking advantage of the double circuit, it is possible to make zinc sinter which is nearly free of contaminators. Lead

Jan 1, 1952

By D. W. Fuerstenau

The United States is rapidly approaching an acute shortage of minerals. According to some observers, this situation may even be more severe than the energy crisis because the US consumes nearly 30% of the world's mineral production. With the mounting competition for world mineral supplies, we can no longer take for granted that foreign mineral products will be available to the US as abundantly as in the past. In 1973, US consumption of mineral raw materials was $35 billion. Of this, $7 billion consisted of imports. Without a drastic reorientation towards the mining of domestic mineral resources, the 1973 $7 billion deficit might mushroom to $100 billion by the year 2000. Thus, a return to domestic sources of raw materials will become absolutely necessary-and will be bucking the trend of the past 25 years, characterized by capital investment for growth in multinational overseas mining operations.

Jan 11, 1975

By D. J. Carney, J. Chipman, N. J. Grant

SINCE the beginning of this century it has been known that hydrogen contributes to the porosity of steel and that it is harmful to its mechanical properties. The evidence for this has been largely qualitative. Steel to which hydrogen was purposely added. in sufficient .amounts was shown to be either porous or brittle or both, whereas similar steel of low hydrogen content was shown to be free of porosity and to possess normal physical properties. There have been a considerable number of qualitative experiments of this type. Also, early in this century, a few attempts were made to measure the amount of hydrogen normally dissolved in commercial steels. This was usually done by placing the sample under an inverted liquid column such as mercury and collecting the evolved gas. These attempts, while not successful in measuring actual amounts of dissolved hydrogen gas, were able to prove that this gas will diffuse out of steel at room temperature, and that the amount of hydrogen dissolved is normally very small. On the basis of such qualitative evidence, hydrogen has been and still is blamed for a great number of the troubles encountered in the steel industry. In recent years, partial solutions for many steel-working problems have been obtained. These have led to increased interest in accurate quantitative work on hydrogen in steel, with the expectation that the results might possibly answer a few of the remaining unsolved problems. Commercially, two of the obvious questions which are in need of an answer are: (1) what are the most important sources of hydrogen, and (2) what quantity of hydrogen can be tolerated in various steels? There are many other unanswered questions. To begin to find the answers it seemed logical to start at the beginning of steel production with the liquid metal. Further, it seemed almost imperative to solve first the problems of analysis and sampling of the metal for hydrogen. Once these problems have been solved, it would be possible to answer more of the important commercial problems mentioned above. As a consequence, it was decided to design an analytical apparatus and, upon satisfactory completion of this, to develop an accurate method of sampling liquid metal for hydrogen.

Jan 1, 1951

By R. T. DeHoff

A new approach to the measurement of the size distribution of particulate structures imbedded in opaque bodies is developed. The method is based upon the assumption of a general two-parameter distribution curve, and the estimation of these two parameters from three well-known counting measurements made upon metallogvaphic sections. The total number of particles in the system is also a product of the analysis. Application of the method with the assumption of the logarithmiconorma1 disfribution function is developed in detail. A complete description of the geometry of a particulate structure requires the determination of the size distribution of particles. The problem of estimating the size distribution of particles of a particular phase in a multiphase system, or the grain-size distribution in a homogeneous system, has been approached by many investigators.'-'0 All of the solutions proposed by these investigators share the following characteristics. a) A minimum of several hundred particle sections in the microstructure must be examined, and some characteristic dimension recorded, such as area,3'5 intercept length,6"9 or diameter.1'2'4'10 b) The resulting data must undergo a series of fairly complex calculations to generate the empirical histogram which describes the size distribution in three dimensions. c) In order to manipulate the result, the histogram must be fitted to some assumed mathematical formula, using the attendant statistical procedures. d) With two notable exceptions,8,10 the particles must be spherical. The measurements and calculations involved are in general very tedious and time-consuming, with the logical result that much effort has been expended in the development of equipment which will perform these tasks automatically and semiautomati-cally.9,11-15 considerable success has been achieved in this area, but the equipment is in general expensive, and usually places stringent requirements On the quality of microstructure which can be reliably analyzed. In laboratories which do not possess such equip- ment, the analysis of geometry is usually limited to measuring total properties of the microstructures, such as volume fraction and interfacial area, because the measurements required are much simpler to make. The determination of size distributions rarely is undertaken. The development which is presented in this paper permits the estimation of size distributions of three-dimensional structures from the same simple counting measurements which are required to determine the surface area and volume fraction of the particulate structure, and one other counting measurement. The basic approach that is used is to assume a general mathematical form for the distribution, which is described by two parameters (as the normal distribution is described by assigning values to the mean and the standard deviation), and then estimate these two parameters from the results of the counting measurements. The introduction of a third counting measurement also permits the evaluation of the number of particles per unit volume, Nv.

Jan 1, 1965

THE Joint Committee appointed to consider a Code of Ethics for Engineers recommends, after delib-erate consideration, that each participating Insti-tute or Society adopt the short simple Code of Ethics following this report. The Committee further recommends that the following method of interpreting and administering the Code be adopted by each participating Institute or Society after any necessary provisions have been, made in the Constitution and By-laws of the Organization. The President of each Society or Institute shall appoint a Standing Committee on Professional. Conduct, to administer the Code of Ethics. The duties of such a Committee shall be to interpret the Code and to render opinions on any cases of ques-tionable conduct on the part of members that may be submitted to the Committee. These interpretations shall be reported to the Executive Board of the Institute or Society who may approve these interpretations, or take such other action as may seem just and necessary. The reports of the Committee on Professional Conduct, when approved by the Executive Board, shall be printed in abstract and in anonymous form in the Institute's or Society's monthly journal for the instruction and guidance of fellow members. This Committee on Professional Conduct shall be appointed in each Institute or Society by the President holding office at the time of the adoption of this Code and shall consist of five member one appointed for five years, one for four years, a third for three years, a fourth for two years and a fifth member for one year only. Thereafter, the President then holding office shall appoint one member annually to serve for five years, and shall also fill any vacancies that may occur for the unexpired term of the member who has withdrawn. These appointments shall he made from among the older members of the Institute or. Society, so that advantage may be taken of their mature experi-ence and judgment. The Committee after appointment shall elect its own chairman and secretary. The Committee shall have power to secure evidence or other information in any particular case not only from the organization's own members, but if it should seem desirable, from men in other professions. The Committee may also appoint sub-committees to consider certain cases when deemed necessary.

Jan 3, 1922

ROBERT M. KEENEY,* Portsmouth, Ohio (written discussion?).- Mr. Coffin has written a most interesting paper that covers most of the uses to which water-cooled devices are subjected; but to meet with the operating department's approval, these devices must effect a saving in cost per ton of ingots produced in the furnace. The making of steel in the open-hearth furnace is dependent entirely on the personal element. It is not possible to charge the furnace with so much raw material, turn on a valve for heat, and by use of recording thermometers, clocks, etc. empty the furnace when a steel is made. Competent men trained to the work must be in charge all the time, and the quality and quantity of steel produced is quite as dependent on the care and working qualities of the furnaces as on the raw material and working of the charge itself. Steel making is hot, hard work and the inducement offered to technical men to take up this work is not sufficient to induce many to enter the field. The result is that most of the workmen in an open-hearth plant, the men who actually operate the furnace and make the steel, are not technical men and do not understand the "whys" and "wherefores " and care less. All this means that a furnace must be built as nearly fool-proof as possible. By this I mean that it is necessary to protect those parts of a furnace most subject to abuse by water-cooled devices whenever possible, and these water-cooled appliances must he as nearly fool-proof as they can be made. The control of the gas entering a furnace is of the utmost importance. This means a properly designed port must have the same design throughout the whole run of the furnace. This is not possible with the ordinary

Jan 6, 1919

By Frank R. Milliken

Before the rather sudden economic downturn in recent months, shortages of materials were painfully felt throughout the US. The current recession has provided a temporary relief here and there-but energy fuels and a number of staples such as sugar are still in short supply. This is an unsolved and fundamental problem that will haunt us again as the economy turns up. There is an awareness that the nation faces a widening supply gap in many of its most basic materials-from asbestos to tungsten-as evidenced by recent studies and government reports, and by the Secretary of the Interior's annual warnings about the mounting seriousness of the problem.

Jan 3, 1975