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Following the suggestion of Engineering Council and at the direction of, the President, representatives from each of the Federal Government bureaus interested in map-making were called into a conference for the purpose of coordinating all of the Government's map-making activities. This conference has now reported back to the President the results of its findings, which indicate that Engineering Council's recommendation in this matter was well founded. While the conference report states that its members were of the opinion that little duplication of effort existed, it recommends the formation of a permanent Board of Surveys and Maps. An extended review of the map-making activities, which is given as an appendix to the report, indicates that this recommendation is a logical step. The conference recommendations concerning this Board of Surveys and Maps are as follows: (1) the Board is to he com-posed of representatives of mapping bureaus to be assisted by outside engineering organizations, which have been named above; (2) the estab-lishment of an information office in one of the Government bureaus, preferably the Geological Survey, which is to be under the supervision of the Board and is to be a mapping information clearing house for the Government and outside engineering organizations; (3) copyright laws are to be so changed that copies of all. maps made in the United States and with Governmental authority, will go to the central information office; (4) the Government departments are to receive orders to cooperate, with the Board; (5) future topographic maps of all kinds are to conform with specifications for the standard topographic map; (6) the U. S. Coast and Geodetic Survey to have supervision of final adjustment of all important control data under specifications approved by Board of Surveys and Maps; (7) surveys in the form of maps and publications are to be issued as soon as possible after field work has been completed; (8) program of the Interdepartmental Committee on Aerial Surveying was approved. Outside technical and scientific organizations that are called in for consultation are to operate in an advisory capacity only, responsibility for action on Governmental work is. to rest solely with the Governmental agencies.

Jan 12, 1919

By T. B. Massalski, Horace Pops

Martensitic transformations were observed by optical metallography and electrical-resistivity measurements during cooling at cryogenic temperatures of the bcc pr-phase Au-Zn alloys. The com-position dependence of the MS, MF, AS , and AF temperatures have been determined. It is concluded that the martensitic platelets which grow mainly in the lengthwise direction and which are associated with a very small temperature hysteresis are "thermoelastic" martensite. In some cases the observed structure seems to have no definite crys-tallographic habit or consists of a mixture of- plates and broad transformed areas. THE majority of the bcc /3-phase alloys in systems of copper, silver, and gold with zinc and cadmium are unstable at low temperatures and undergo a transformation upon further cooling into another structure. A large number of such transformations are martensitic. The composition dependence of the Ms temperatures has been determined and reported for CU-~n,' Ag-Cd,' and AU-C~~ alloys. The 50 at. pct ordered Au-Zn p' alloy has been reported by Jan and pearson4 to transform martensitically at 58°K in connection with their study of the de Haas-van Alphen effect The p' phase in the Au-Zn system has the ordered CsC1-type structure. The phase field is shown in Fig. 1: it has the typical V shape which is characteristic of all copper-, silver-, and gold-based binary /3-phase alloys. There appears to be no a priori reason why the transformation should be limited to the equiatomic composition and the availability of a cryogenic stage for optical metallography5 has permitted studies down to the liquid-helium temperature of a series of alloys in this system. EXPERIMENTAL PROCEDURE Predetermined weights of 99.999 pct pure gold and zinc were melted and cast under a partial atmosphere of helium in sealed quartz capsules. Thorough mixing of the molten metals was achieved by vigorous shaking, followed by a rapid quench into a brine solution. All ingots were homogenized at 640°C for 4 days. The loss in weight was usually less than 0.04 wt pct and was assumed to be due to

Jan 1, 1965

By John B. Myers

VERMICULITE is a name used to describe micaceous material that exfoliates when heated. It is hydrated magnesium-aluminum-iron silicate. The chemical composition, color, physical appearance, and degree of exfoliation vary. COMPOSITION, PROPERTIES, AND ORIGIN Vermiculite has the characteristic micaceous structure of basal cleavage and readily splits into thin laminae, which are soft, pliable, and inelastic. The monoclinic crystal faces are often marked by triangular lines at 60° and 120°. Hardness is 1.5; specific gravity, 2.2-2.7; luster pearly to greasy; colors, amber, bronze, reddish brown, dark green, and black. Feel is soapy, particularly when wet. When heated it exfoliates by expanding at right angles to the cleavage into long wormlike pieces (the name vermiculite is from the Latin veamiculari, to breed worms). This important characteristic of expansion is believed to be a mechanical separation of the layers when the contained water is converted into steam. Warping of the unit layers may also contribute to the expansion. The increase in bulk volume of commercially prepared material is 8 to 12 times but individual flakes may increase in size more than this. Pure vermiculite is a distinct mineral and has the structural formula (OH), (Mg,Fe)3 (Si,Al,Fe)4 010.4H20. It rarely occurs in this pure form, but generally as a mixed mineral of varying structure. One explanation is that the mixed material is composed of unit layers of inter-stratified pure vermiculite and biotite. The essential difference between the two is that unit cell structure of vermiculite contains a layer of water molecules whereas the biotite cell contains potassium instead of the water. The water content of the mixed vermiculite is less than that of pure vermiculite but more than that of biotite. Pure biotite does not expand when heated. If the proportion of biotite layers in a vermiculite is too high it will adversely affect the degree of exfoliation. Within a given deposit, the great mass of material may approach a definite com-position with local areas of greater biotite content. It is not uncommon to find also small pockets of pure biotite but these are generally segre-

Jan 1, 1949

By G. B. Pryde, R. M. Magraw

In laying out a new mine, provision should be made for the ultimate recovery of as much coal in any given bed as is consistent with safety and economic mining. Though each mining district, if not each individual mine, has problems that make the adoption of any hard and fast rule impossible, certain basic principles are adapted to practically all conditions. One of the most vital is the provision for barrier pillars of ample dimensions to protect all haulage and permanent airways during the life of the property. Where conditions permit, room or butt entries should be driven on the strike or slightly to the rise, and rooms turned at right angles to these entries. The width of rooms and room pillars is governed by conditions prevailing in the mines under consideration. A safe rule is: In advancing, extract not more than 25 to 35 per cent. of the entire seam; in exceptionally thick seams, considerably less than 25 per cent. should be taken. Rooms usually vary in length from 250 to 350 ft. (76 to 106 m.) with a barrier pillar of not less than 80 ft. between the last crosscut. in rooms and the back entry of the level above. All entries, rooms, and entry-and-room crosscuts should be driven .on sights and room crosscuts should be driven at, right angles to the direction of the rooms. In mines under excessively heavy cover or where roof conditions are bad, rooms should be driven narrow and a barrier pillar left at every fifth to tenth room. This barrier should be of such dimensions that one or more rooms, with pillars of usual dimensions, may be turned through it when the barrier is no longer required. Two of the advantages of such a barrier are the protection of the panel against peaking of roof load during pillar extraction and the easy closing of the entry in case of fire. Where economic conditions permit, it is preferable to follow the retreating panel system of mining. In the case of coal that outcrops, and even in cases where no outcrop is exposed, it is preferable to commence pillar extracting on the high side of the mine. Where the retreating

Jan 1, 1922

By Bernard MacDonald

Introduction. OF the treatment of the slime-pulp of gold- and silver-ores by cyanidation, agitation is an essential part. When prepared for treatment, this pulp, consisting of ore reduced to such fineness that approximately 80 per cent. of it will pass through a 200-mesh screen, is mixed with a certain proportion of water, carrying in solution the quantity of cyanide (KCN) and other chemicals required. The water-constituent of the pulp thus prepared usually ranges from 1 to 2 parts by weight to 1 of the dry ore. Thus constituted', the pulp is charged into treatment-tanks, the shape and capacity of which vary, according to the quantity of pulp to be treated daily and the method of agitation to be employed. Tanks have no other function in a cyanide-plant than that of being economical and convenient containers or receptacles for holding the pulp, solution, or water used in the operations. It is by agitation that the solids in the pulp charged into the tanks are kept in suspension in, and mixed with, the solution in the proper proportions required for the treatment. If the proper mixture of solution to solids be determined to be 2 to 1 by weight (which is, approximately, 5 to 1 by volume), this proportion should be maintained in every part of the charge ; -that is, each solid particle of the pulp, whether it be of 180- or 400-mesh size, should, be surrounded by five times its own volume of solution throughout the whole period of treatment. The reason is, that the amount of chemicals ascertained to be necessary for dissolving the gold and silver contained in the solids, is held in uniform solution in the water-constituent of the pulp, and, therefore, the determined proportions of solution and solids must be maintained at all times during treat-

Apr 1, 1912

By R. J. Woody

DESIGN of the most economic continuous counter-current decantation (CCD) circuit is based on selection of the number of stages and the wash volume that will give the minimum summation of the following items: 1) Capital and operating costs of the CCD circuit. 2) Capital and operating costs of the precipitation circuit. 3) Value of the dissolved product lost.

Jan 7, 1958

By Donald L. Katz

FIFTEEN years ago Dr. Manning published a paper in "Petroleum Development and Technology" on '.Fundamental Research Relating to Petroleum." He tabulated for several industries "the proportion of their present success which can be fairly attributed to the application of information and processes obtained by scientific research," giving petroleum a score of 7 compared to 100 for the electrical and coal-tar industries. Today the petroleum industry as a whole and the producing groups both have raised their score beyond the majority and are climbing toward the top. Present practices are being developed both by fundamental research and the application of the research method in field operation.

Jan 1, 1941

By R. B. Porter, R. P. Porter, R. A. Lothrop

Changes became necessary in dredging methods employed in Idaho through passage of the Dredge Mining Protective Act (1954). Among other provisions, the law requires dredge operators to construct settling ponds of sufficient capacity and character to reasonably clarify the water used in the mining process before such water is discharged into the stream. Porter Bros. Corp., a placer mining company with many years operating experience in Oregon and Montana, became interested in strategic mineral placers in Idaho in 1950 when it was learned that prospectors had discovered a radioactive mineral deposit in Bear Valley Creek, 95 miles northeast of Boise. The company acquired mining leases and proceeded with exploration and development work on the property. After extensive research had resulted in the determination of successful separation processes, contracts were negotiated with the federal government and deliveries of columbium-tantalum and uranium concentrates commenced in 1956. The mining operations are located in a primitive area of Idaho among salmon spawning grounds and crystal-clear mountain trout streams. To avoid involvement in a very controversial issue, it appeared advisable for the company to develop water treatment procedures exceeding those requirements stated in the Idaho Dredge Mining Protective Act. Operation: The company operates one 6 cu ft continuous bucketline dredge and one 4 1/4 cu ft continuous bucketline dredge on the property. The dredges are jig-equipped, with feed being screened to 3 in. by trommels. The screening and gravity concentration methods satisfactorily separate the heavy minerals from companion clays, sand, and gravel. However, this separation of the heavy minerals requires water from the dredge pond with a minimum content of silt and colloids; therefore, water for dilution is added continuously to the dredge pond to suppress solids buildup. Discharge of this highly turbid water to maintain the proper pond level would ultimately result in an excessive silt load in Bear Valley Creek. To prohibit the turbid pond water from flowing directly into Bear Valley Creek, it was necessary to isolate the dredging area. Main by-pass canals were constructed along each side of the dredge pond and numerous secondary canals were dug for diverting seepage and snow runoff. One by-pass canal, extending more than two miles along the west side of the valley, diverts the main stream as well as tributaries entering from the west; a canal east of the dredge area diverts streams entering from that direction. At the beginning of operations in 1956, the dredge pond effluent was filtered through tailings and settled by use of coagulents in a series of lagoons. The filtrate was then discharged directly into the stream. Although this procedure gave satisfactory results in conformance with the state law, ice buildup and lagoon freezing hindered the efficiency of the process during periods of low temperature. For this reason, testing began in 1956 on a water treatment process that would operate efficiently under the extreme weather conditions encountered in Bear Valley. Development of Water Treatment System: Porter Bros. Corp. established the following requirements for effective continuous treatment of dredge pond effluent to the stream which, at low flow conditions, effluent to the stream which, at low flow conditions, would not result in a turbidity exceeding 25 ppm in the stream, 2) produce a sludge sufficiently dense to minimize disposal area requirements, 3) be semi-portable to follow dredge movements, 4) be capable of operating at low temperatures, and 5) be capable of handling a variety of capacities and turbidities.

Jan 1, 1961

By E. R. Russell, N. E. Richards

The current ejyiciency of aluminum cells was derived from the metal produced over a period of time and the theoretical faradaic yield. The difference in the actual amount of aluminum in the cathode at the beginning and end of the period must be determined. The weight of aluminum in the cathode was calculated from the dilution of an added quantity of impurity metal. Use of multiple indicator metals, copper, manganese, and titanium, demonstrated that the weight of aluminum in cells can be determined to within 1 pct with routine but careful chemical analyses. Over intervals of the order of 30 days, current efficiencies reliable to within 1 pct can be obtained. INVESTIGATIONS beginning with those of Pearson and waddington ,' through the most recent published work of Georgievskii,9-11 illustrate the direct relationship between the composition of the anode gas and the applicability of analysis of anode gases to the control of alumina reduction cells. McMinn12 noted the lack of an independent method for measuring cell production efficiency over the short term. There is no doubt that changes in the current efficiency are immediately reflected in the composition of anode gases. However, the accuracy of faradaic yields calculated from gas analyses depends upon the degree of interaction between primary anode gas and Carbon.6 A conventional industrial practice of obtaining long-term current efficiency for production units from mass balances and quantity of electricity is generally insensitive to the impact of planned control of any one or more of the influential reduction cell parameters such as temperature, alumina concentration, and mean interelectrode distance. Consequently, there is a real need in the aluminum industry for a procedure to obtain the absolute cell current efficiency over a short term—10 to 30 days—both for the calibration of values obtained from gas analysis6 and for evaluating the effect of controlling specific parameters in the reduction process. The amount of aluminum produced may be determined by considering the cathode pool as a reduction of an impurity metal in aluminum. Analyses over a period will show a decreasing concentration of the impurity due to the accumulation of aluminum solvent. The increase in aluminum inferred from analyses is the amount produced by the cell during the period. Combining weights of the cell aluminum in the cathode at the beginning and end of a specific period, weights of aluminum tapped and the quantity of electricity passed during the interval will yield the current efficiency. Smart,I3 Lange;4 Rempel,15 Beletskii and Mashovets,16 and winkhaus17 have used dilution techniques to determine aluminum inventory in alumina reduction cells. A technique for determining the weight of aluminum in production cells by addition of small amounts of copper to the aluminum cathode was described by smart.13 The precision in values of the aluminum reservoir through dilution of copper in the cathode ranged from about 1 to 3 pct depending upon the quantity of copper added in the range 0.2 to 0.01 wt pct, respectively. Because the method appears so direct and apparently simple, one would not anticipate difficulties in application to industrial cells. The objective of this study was to resolve this problem associated with the trace metal dilution technique for determining the amount of aluminum in a cell. The approach in evaluating trace metal dilution as a basic factor in determining the weight of aluminum in the cell reservoir, and the absolute current efficiency of the Hall-Heroult cell, was to dilute more than one trace metal in the aluminum cathode so that we could discriminate among complications arising from physical mixing, the possibility of separation of intermetallic compounds, loss of the added elements, and chemical detection. EXPERIMENTAL METHODS These experiments are not complex but require standardized procedures. The technique involves addition of the trace metals to the cathode, knowing when these metals are homogeneously distributed in the liquid cathode, timing of the sampling, employing accurate and precise analytical methods, using reliable procedures for monitoring the amount of electricity passed through the cell, and accurate weighing of aluminum removed from the cell during the particular period. More accurate results might be obtained if the increment in concentration of the added indicator metals were of the order of 0.1 to 0.2 wt pct. The method must be applicable to production units and, hence, the contamination of the aluminum minimized. For this reason, the concentration of trace metals in the cathode was kept below 0.07 wt pct and generally at 0.04 wt pct level. Trace quantities of copper, manganese, titanium, and silicon are already present in virgin aluminum and are suitable as additives from electrochemical and analytical points of view. Concentration of silicon is quite dependent upon the characteristics of the raw materials and was not used extensively in this work. Chemical Analyses. All instrumental analyses require calibration against an absolute technique such as a gravimetric, volumetric, or spectrophotometric method which represents the ultimate in sensitivity, precision, and accuracy. On review, the best methods for copper appeared to be optical absorption without

Jan 1, 1969

By Joe B. Alford

Jan 1, 1971

By George Collins

AT the meeting of the Western Division of the American Mining Congress, held in Denver last September, papers were read by F. H. Brownell, a vice-president of the American Smelting and Refining Co. and chairman of its finance committee, and by H. Foster Bain, former director of the United States Bureau of Mines and now secretary of the A. I. M. E.. which dealt thoroughly with certain phases of my sub-ject. These addresses can hardly have failed to awaken serious reflection in all who listened to them; but their implications have apparently not penetrated the con-sciousness of bankers, economists and statesmen, whose business it is, or should be, to prepare for the economic and social changes which must inevitably follow, if the conclusions which I shall outline hereinafter are true. In discussing this subject I wish to disclaim any intention or desire to forecast the course of the metal markets or the immediate prospects of the mining in-dustry. The facts' adduced must inevitably influence the value of metals, the activity and profitableness of mining, and perhaps also the social status of those en-gaged in it. But my forecasts do not refer to this year, next, year, or the year after. The nearest ap-proach to a date on which I will venture is that the relative scarcity of gold may begin to make itself felt in something like ten years from now, but its effect will not culminate for several years thereafter. Scarcity of new gold is likely to be offset, to some extent, by increasing use of currencies based on credit; but unless it is found possible to dispense with the gold standard altogether, this can hardly prevent a great ultimate fall in commodity prices. This fall, moreover, is likely to be more severe in manufactured goods than in what are, popularly termed raw ma-terials; and most of all in those manufactured goods which are susceptible to the greatest degree to cheapen-ing by mass production, and which are least counter-affected by increasing metal prices; by which I mean those in which the cost of metal contained forms a relatively small, element in the total cost of production.

Jan 6, 1927

INTRODUCTION Mineral explorationists range throughout the world looking for mineral deposits which can subsequently be made into mines. Mines are not found! Mines are made, usually at great cost and not often without significant risk. The process of making a mineral deposit into a mine involves a great deal more than a complete appraisal of the deposit. The making of a mine demands detailed feasibility studies of many factors, any one of which, if shown to be negative, could prevent the deposit from becoming a successful mine. Total feasibility analysis involves at least three major fields of study: (1) economic analysis, (2) financial analysis, and (3) political and environmental analysis. Economic analysis is essential for proper decision making at many stages in the evaluation of a mineral deposit. It is the yardstick by which the proposed mining project and alter- native investment opportunities are measured. Economic analysis is concerned with costs and potential profits and can be applied at various stages in the evaluation of a mineral deposit to determine if the project merits the additional funds necessary to bring about each succeeding stage. The nearer any deposit approaches to becoming a mine, the more carefully the economic analysis should be made. Financial analysis has reference to how, where, and at what cost the investment funds can be obtained to finance the proposed mine project. Political and environmental analysis has reference to the many intangible factors that can affect the making of a successful mine. These factors loom larger today than ever before, due to the profusion of government regulations and various environmental constraints now imposed upon the mineral industry both by law and by the weight of public opinion. Ultimately, many of these intangible factors can be resolved back into the economic analysis as an added cost to mine development, but more and more often they have become insurmountable obstacles to any development of certain deposits. The role of financial analysis and the analysis of intangible factors must never be underestimated when making a feasibility study upon which to base investment decisions; however, the emphasis of this text will be upon economic factors. THE PARAMETERS OF MINERAL ECONOMIC ANALYSIS The two major elements of economic analysis are: 1) The potential earnings or annual generated cash flow of the project. 2) The investment costs necessary to realize such earnings. If the difference between the two elements is large enough, i.e., if the return on investment from the cash flow is high enough to attract investors, the project can be said to be financially feasible. The mineral economic analysis must take into consideration many parameters, some of which are known or knowable within certain limits, and others of which are unknown or unpredictable within certain limits and for which estimates must be made. Because both known and estimated parameters enter into the same analytical computations, it is important for the analyst to realize the nature of each when considering the results of an analysis. Some parameters such as the grade of mining block, although estimated, are said to be known within mathematically defined limits. Other parameters, such as the future price for minerals produced, etc., can only be estimated or "guestimated" within reasonable limits for which no precision can be assigned. Known or Knowable Mineral Economic Parameters Known or knowable parameters are: 1) Tonnage and grade of valuable minerals for the total mineral body and for individual mining blocks. 2) Metallurgical recovery of valuable mineral. 3) Minimum operating life of mineral de- posit at any specified production rate. 4) Royalty schedule, property payments, etc. 5) Sales-purchasing agreements, smelter schedules, marketing contracts, etc.

Jan 1, 1980

By Harry H. Power

WHILE the attention of all engineering branches is focused today on changes and improvements in the several curricula, we are concerned here with the many questions arising in industry and college concerning the preparation for the petroleum engineering profession. The succession of problems confronting the petroleum engineer demands a degree of versatility not ordinarily encountered in other professions. As a consequence, the student cannot acquire mastery of all the several engineering branches represented in field practice, and as an alternative, he has learned to appreciate the value of thorough training in the basic or fundamental sciences as a preliminary foundation for professional work. While our attention is directed primarily to the training of engineers in educational institutions, it is necessary that the ultimate education of the professional engineer be kept in mind. It is apparent that his success as an engineer is limited not only by his educational and job experience, but by his native endowments: mentality, personality and health. The engineer's lack of job experiences often proves as much a handicap as the lack of adequate college training. If the final product proves to be satisfactory, both industry and technical institutions are to be congratulated. However, if the product is found wanting, the one most responsible should be apprehended. FITNESS FOR PROFESSION For the most part, students of engineering colleges have had their interests in applied science awakened at a relatively early age. Many of them entered college as a convenient means of acquiring a technical education, but undoubtedly would have had better prospects in a shorter program offered by institutions of noncollege grade. The activating motive of practical interest is also strong in students suitable for college training, but in many cases an intellectual interest must be awakened in order that it may survive graduation. Numerous engineers believe that this progressive process of selection and determination of career aims is one of the essential services rendered by the engineering colleges. Industrialists, who are more interested in quality than quantity of petroleum engineering graduates, have pointed out the good that should result if more emphasis were given to the work of eliminating the misfits. They also point out the protective measures that have been taken by other professions for the betterment of professional standards. Mention has been made of the beneficial results to be obtained by collective determination of the market for the products of engineering schools, particularly in that the students unsuited to the profession would have an opportunity to prepare themselves for employment more suited to their personalities and other qualifications. In the event that such a system of coordinated personnel direction is developed by the

Jan 1, 1941

By Harry H. Power

WHILE the attention of all engineering branches is focused today on changes and improvements in the several curricula, we are concerned here with the many questions arising in industry and college concerning the preparation for the petroleum engineering profession. The succession of problems confronting the petroleum engineer demands a degree of versatility not ordinarily encountered in other professions. As a consequence, the student cannot acquire mastery of all the several engineering branches represented in field practice, and as an alternative, he has learned to appreciate the value of thorough training in the basic or fundamental sciences as a preliminary foundation for professional work. While our attention is directed primarily to the training of engineers in educational institutions, it is necessary that the ultimate education of the professional engineer be kept in mind. It is apparent that his success as an engineer is limited not only by his educational and job experience, but by his native endowments: mentality, personality and health. The engineer's lack of job experiences often proves as much a handicap as the lack of adequate college training. If the final product proves to be satisfactory, both industry and technical institutions are to be congratulated. However, if the product is found wanting, the one most responsible should be apprehended. FITNESS FOR PROFESSION For the most part, students of engineering colleges have had their interests in applied science awakened at a relatively early age. Many of them entered college as a convenient means of acquiring a technical education, but undoubtedly would have had better prospects in a shorter program offered by institutions of noncollege grade. The activating motive of practical interest is also strong in students suitable for college training, but in many cases an intellectual interest must be awakened in order that it may survive graduation. Numerous engineers believe that this progressive process of selection and determination of career aims is one of the essential services rendered by the engineering colleges. Industrialists, who are more interested in quality than quantity of petroleum engineering graduates, have pointed out the good that should result if more empha¬sis were given to the work of eliminating the misfits. They also point out the protective measures that have been taken by other professions for the betterment of professional standards. Mention has been made of the beneficial results to be obtained by collective determination of the market for the products of engineering schools, particularly in that the students unsuited to the profession would have an opportunity to prepare themselves for employment more suited to their personalities and other qualifications. In the event that such a system of coordinated personnel direction is developed by the

Jan 1, 1941

By M. W. BERNEWITZ

IT is 27 years since I last visited Broken Hill, New South Wales, one of the world's greatest lead-silver-zinc districts. Then, the flota¬tion of ores was in its infancy. The Minerals Separation process had its birth as a practicability in the Central Mill, which is still operating and yielding high recoveries. The average Australian knows that Broken Hill is an important mining center in a "corner" of New South Wales, but he does not know what a factor it is in the lead, silver, and zinc production of the world. Nor does he realize that among the ramifications arising from metal production at Broken Hill are the great lead smelter at Port Pirie, South Australia, 254 miles southeast; the electrolytic zinc works at Risdon, and the limestone mine at Davenport, Tasmania; the acid works at Cockle Creek, New

Jan 1, 1935

By Wallace F. Lovejoy

The conservation of mineral resources as a public policy question has received a great deal of attention in the area of petroleum and practically no attention in other mineral areas, except, of course, soil and water. Some insights into mineral conservation problems and how these problems can be approached in the social decision-making process are significant. THE MEANINGS OF CONSERVATION Conservation means many things to many people .2, 11 Too often it is a label attached to a proposed program or policy to add respectability and to gain public acceptance. It is a term applied to specific resources in some contexts and to resources generally in other contexts. The oft-quoted comment of President William Howard Taft that conservation is something everybody is for, no matter what it means, succinctly illustrates the confusion over both the meaning of the concept and the policies required to implement a conservation program. This confusion goes quite deep and is more than a matter of semantics or emphasis. For example, the efficient exploitation of a mineral deposit which might be applauded as good conservation in terms of that mineral, might well result in destruction of or harm to the environment which might be viewed as bad conservation. Economics provides some tools to help solve this sort of problem, but there may be fundamental differences in value systems among groups in this society, so that ultimately society must collectively make a subjective political choice as to what is good or bad conservation policy.a An Economic Definition of Conservation The economic concepts of conservation have more relevance and are more easily applied to minerals than to many other natural resources. This does not mean that economics goes all the way in understanding mineral conservation, but at least it provides a framework for analysis which later can be altered to include noneconomic variables. Perhaps the greatest confusion in discussing mineral conservation arises in attempting to relate purely physical concepts with economic concepts. An economist is interested in maximizing or conserving values; he is not interested in maximum physical recovery or utilization. He wants to know the costs and benefits of using, or not using, resources. The economic theory of mineral-resource conservation can be labeled variously as the theory of exhaustion, the theory of resource exploitation, the theory of resource utilization, or simply as a special case of the broad theory of capital.4,28 Consideration of these labels illuminates the concerns of the econo-

Jan 1, 1976

By John Chipman

DESPITE the rapidity of chemical reactions at steelmaking temperatures, deoxidation reactions cannot be expected to reach equilibrium immediately after addition of a deoxidizing agent. A considerable period of time may be required merely to obtain complete mixing of the deoxidizing element throughout the volume of steel to which it is added. Evidence in the literature indicates that in some cases the time is long compared with that allowed for completion of the experiment or for teeming of the heat. The great turbulence observed during the filling of the ladle is no guarantee of complete dispersion on a fine scale throughout the heat. During the process there are initially certain volume elements which are high in deoxidizer and others which retain substantially their original oxygen content. Mixing consists of the subdivision and ultimate destruction of these liquid segregates through the process of shear and elimination of concentration gradients by diffusion. The shear process does not continue indefinitely and a quiescent state may be reached in the ladle before all volume elements of divergent deoxidizer and oxygen content are completely eliminated. In furnace deoxidation the time required for complete mixing may be very long unless continuous stirring is employed.' In Fig. 1, let the circle represent one small volume element of aluminum-rich metal surrounded by oxygen-rich steel in which no stirring movement remains. Further mixing requires inward diffusion of oxygen and outward diffusion of aluminum, resulting in precipitation of A12O3 in the diffusion zone. It is important to note that such a precipitate may itself interfere with the diffusion process. Moreover, if the precipitate forms as a film with even minimal mechanical strength, it may interfere not only with diffusion but with shear as well, thus stabilizing compositional differences in volume elements of greater than microscopic size. A film surrounding such a volume element would have little or no ability to rise or to sink unless it enclosed a liquid whose density differed from that of the ambient. Consider now the effect on the overall composition of the melt. Fig. 2 represents the A1-O equilibrium at the temperature of the bath. High-aluminum elements of composition X may exist alongside high-oxygen elements of composition Y in such proportions that the average composition 2 has a much higher A1-O product than that corresponding to equilibrium. The A1-O product supposedly corresponding to equilibrium at 1600 °C was found by Wentrup and Hieber2 to be 10-10, by Hilty and crafts3 to be 2 X 10-9 and by Gokcen and chipman4 to be 2 x 10-14. Only the last named investigators approached equilibrium by means

Jan 1, 1962

By Cornelius Kelley

I HAVE been asked to pay a tribute to the mining industry. It is appropriate to this occasion that a word upon this subject should be spoken to this assemblage; but to pay a tribute to the mining indus-try, one that would be worthy of its traditions and its accomplishment and that would outline what it has meant to the economic and social development of this nation, would carry me far beyond what must be the brief confines of this address. I wonder how many there are who have ever paused to reflect how different might have been the current history of the world had it not been that for nearly eighty years a never-interrupted stream of wealth has flowed from the storehouse of treasure in the mines of the West into the commercial and economic life not only of this nation but of the world. Truly it was a historic day that Marshall discovered in the runway at Sutter's mill the glistening particles that proved to be gold. That event was one of the most momentous events in its consequences that ever happened in the history of mankind. Without its occurrence this nation undoubtedly would have grown; it would have reached a position; of economic and social soundness; but certainly it could not have achieved the splendid and immediate results that have become our proudest heritage and established our unrivaled posi-tion in the industrial world. As the primal cause that led to one of the great migratory movements of man it stands alone, unequaled, without any precedent in the annals of history, comparable in its effect on the imagination, on the movement, and on the devlop-ment of a people. Nearly three-quarters of a century had passed since the banners of the Revolution had been furled and a new nation had come into existence. Beyond the boun-daries of the original colonies, and through the passes of the Alleghanies, hardy frontiersmen had cut their way, and the process of establishing what have become -great states in the Valley of the Mississippi was under way. An empire of virgin land beckoned to the home-seekers of the world; but scarcely had its occupation been begun when, true to the instinctive urge that meant the ultimate destiny of the nation, there began the movement to carry the Stars and Stripes westward to the Pacific. Within the boundaries of what was then Mexico, Americans fought and died in the Alamo, and the banner of the Texan had been raised in eager ex-pectancy that its Lone Star might be added to the grow-ing constellation on the American banner.

Jan 5, 1928

By A. E. Lillstrom

IN the development of iron mines and production of iron ore from the Marquette range, drilling blast-holes is an important phase of the mining cycle. The ground drilled in ore production can be classified into two main categories, soft hematite and hard hematite or magnetite. Within these categories the material exhibits a wide range of penetrability by percussion drills. Development work encounters various types of rock. Slate and altered basic intrusives constitute the softer types commonly encountered. Harder materials are represented mainly by greywacke, quartzite, iron formation, and diorite. Prior to the first tungsten carbide trials in late 1947 and early 1948, hard-rock and ore drilling was done with steel jackbits starting at 21/4-in. diam. These were reconditioned by hot milling. Automatic or handcrank 31/2-in. drifters were employed, mounted on Jumbos, posts and arms, or tripods, depending upon the working place. With the exception of shaft sinking jobs where 55-lb sinker machines were and still are used with 1-in. quarter octagon steel, the other production and development mining utilized 11/4-in. round and Leyner-lugged steel. The following properties have been selected as typical examples wherein carbide bit applications have proved economical. The Mather mine "A" and "B" shafts and Cleveland-Cliffs Iron Co. mines are soft ore mines where insert bits are used in rock development only. The Greenwood mine, Inland Steel Co., Champion mine, North Range Mining Co., and Cliffs shaft mine, Cleveland-Cliffs Iron Co., are hard ore mines where all drilling is done with tungsten carbide bits. Mother Mine "A" Shaft In the Mather mine "A" shaft and other soft ore properties where only rock development work is done with the tungsten carbide bits, several types and makes of bits have been tried since early 1948. The greatest proportion of failures have been at the connection end, although the early trials with the 13 Series Carset 11/2-in. bit used in conjunction with 31/2 -in. automatic-feed drifters, showed an equal amount of shattered inserts. To combat this shattering, the 31/2 -in. drifters were replaced by 3-in. drifters, thus eliminating, for the most part, insert failures. However, the attachment end of the rod continued to be the main source of trouble. The greatest amount of failure was in the stud or at the upset section approximately 2 in. behind the drive shoulder of the rod. Heat treatment was changed several times as well as the composition of the alloy studs. Since this failed to correct the trouble, a decision was made to change to a heavier attachment section. Timken 11/2-in., type M, bits were then employed and showed an exceptional improvement. The rods are discarded when the thread contour shows sharpening or wear on the shoulder. It was also learned that the Timken insert did not show as rapid gage and cutting edge wear as did competitive makes, and footage per use increased by approximately 50 pct. Prior to the Timken trials the average life per bit at the Mather mine "A" shaft on 6-ft change chain-feed drifters was 500 ft, and the rod life at the connection end was 50 ft. The Timken bit with chrome-plated thread averaged 1200 ft, and rod life increased to as much as 500 ft. However, the life of the connection end was much better on shorter length drill rods or in places where machines with 34-in. change were used. The bit thread continued to be the point of ultimate failure with thread strippage, constituting the cause for discard of bits. In one of the new development headings, harder rock was encountered for approximately 800 ft, dropping the life per bit to a low of 90 ft with shank and thread life of rods dropping to approximately 125 ft average. The stripped bits were then welded to the rods, increasing the life per bit by 75 to 100 pct. The rod transportation for main level development was not a problem so intraset rods were tried. Intraset rods have tungsten carbide inserts set into the rods proper by the manufacturer and can be obtained with chisel or four point bits. This type of rod eliminates the need for any connection and the steel being a special alloy will show more feet drilled per rod. The first trial was made with eight rods, and final results averaged 350 ft per rod, six of the rods worked the life of the bit end, and two broke shanks at less than 50 ft. The preceding example showed a considerable improvement, so additional steel of the same type was purchased, but its use has been limited to main level drifting only, because of the handling problem involved in transportation of the complete rod to mine shops for resharpening. Further trials are being made on improving the life per detachable bit by chrome plating. To date, the chrome plating shows an improvement of approximately 100 pct. However, final results will not be known until the present long term trials have been completed. Mother Mine "B" Shaft In November 1947, tungsten carbide bits were first tried at the Mather mine "B" shaft. The use of 1%-in. Carset 13 Series bits, for drilling the 72-hole, 7-ft shaft round, decreased the drilling time from an average of 41/2 hr per round required with steel bits, to 2 hr with insert bits. The best drilling time for

Jan 1, 1952

By AIME AIME

IN many countries the lack of liquid petroleum supplies has centered interest upon the hydrogenation of coal and coal tars for the preparation of motor fuel. In the United States, hydrogenation has been of greater interest for grading up low-value petroleum fractions to the more valuable volatile fuels and for the preparation of a variety of premium products, including aviation gasolines, solvents, Diesel fuels, and lubricating oils. Chemically, the basic reason for this process is that, as shown in Table 1, the ratio of hydrogen to carbon (H/C ratio) in available raw materials is quite different from that characterizing the products sought.

Jan 1, 1936