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By W. J. Uren, Charles R. Kuzell

The industries engaged in winning minerals from the earth, because of their widespread dissemination, are faced with perhaps as wide a variety of labor-management problems as may be found in any other broad sphere of productive activity. Those problems are continually increasing in volume and complexity, and management has become aware of their growing importance. For the past quarter century at least, labor-management problems have largely been union-management problems. During this period tremendous assistance has been given labor unions through legislation and administrative and political action. In the United States, legislation favorable to unions has come about in the form of the now defunct National Industrial Recovery Act; the Wagner Act, most of which has been carried forward in the Taft-Hartley Act and the Landrum-Griffin Act; the Norris-La Guardia Act, the Wage and Hour Law, the Walsh-Healey Act, and others. The result has been to transfer from the hands of management to those who direct the affairs of the unions a large share of control over the industry and to hamper in many ways the remaining control left to management. In the United States there are many examples of the power of unions to injure whole industries seriously without regard to the interests of management, the employes, or the public. During 1958 and 1959 revelations of corruption and coercion in labor unions made before the McClellan Committee of the U. S. Senate generated considerable public sentiment in favor of legislation to protect the interests of employes and the public. However, the resulting legislation, the Labor-Management Reporting and Disclosure Act of 1959 (Landrum-Griffin Act), demonstrated quite clearly that the political power of the labor union leaders was adequate to prevent adoption of effective measures in this field.

Jan 1, 1964

By A. R. T. Denues

LIQUID-OXYGEN explosives commonly consist of a carbonaceous absorbent enclosed in a canvas wrapper and soaked with a liquid con-taining more than 90 mol per cent of oxygen. Investigation of these explosives in this country was initiated in 1917 by George S. Rice, then Chief Mining Engineer of the Bureau of Mines. The early development is summarized in two papers.1,2 Their characteristics, advantages and disadvantages were considered in a recent bulletin of the Bureau of Mines.3 Other publications of this Bureau4,5 treat the technology of these explosives and contain adequate references to pertinent literature. These investigations defined the properties of liquid-oxygen explosives and improved them greatly; however, an outstanding disadvantage is their high inflammability, a property of critical practical importance. These explosives as hitherto prepared are easily inflamed; the combustion resulting from an accidental ignition is particularly dangerous because of the ease with which it passes into detonation. For this reason the Bureau of Mines undertook a cooperative investigation, which has resulted in the development of fire-retardant treatment for the minimiza-tion or elimination of this hazard without materially impairing the explosive properties, including the ease of detonation. This presentation will offer a general description of the investigation and the outstanding results. Further phases will appear in subsequent short papers, and the entire investigation including the results of detailed experiments will be available in a forthcoming bulletin of the Bureau of Mines (Bull. 429). The effects produced by fire-retardant treatments of the carbonaceous absorbent and of the canvas wrappers were investigated separately, and the efficacy of combinations of these treatments with particular reference to the possibility of inflammation and to the development of detonation from inflammation was studied. The experimental explosive was pre-pared from a granular carbonaceous absorbent and the results described may be more or less unique for such a material. An extensive preliminary

Jan 1, 1940

Note Any member who desires to be designated as being "Available for Consulting Work" can arrange it simply by sending a written request to the office of the Secretary of the Institute The following list of members is primarily arranged geographically, with secondary consideration to political subdivisions arranged alphabetically First, the states of the United States , then other North America, in order Alaska, Canada, Mexico, the West Indies, and Central America Then cones South America, Europe, Africa, and Asia, each including the near by islands associated with those continents Australia, the islands to the north, and the Pacific islands except Japan are grouped together under Oceania The various countries are indexed on the preceding page NORTH AMERICA UNITED STATES ALABAMA America -Dyar, G C Anniston -DePriest, S H Klugh, B G Lefforge, J W Auburn Poor, R S Bankhead -Armstrong, W D Bessemer -Beck, A IV, Jr Carnes, D Chabot, L S , Jr Creveling, J C

Jan 1, 1952

By T. E. Leontis

The specific effect of various rare-earth metals on the room- and elevated-temperature properties of magnesium has been evaluated. Alloys containing didymium exhibit the highest tensile and compressive strengths at room and elevated temperatures. All the rare-earth metals increase the creep resistance of extruded magnesium at temperatures in the range of 400° to 600°F, but the degree of enhancement depends on the temperature and on the concentration of the added metal. THE effects of rare-earth metals on the properties of sand-cast magnesium were discussed in some detail in earlier paper by the author.' The present paper deals with the effect of the same alloying elements on the properties of extruded magnesium. This investigation also had as its aim the development of a wrought alloy having a better combination of room-temperature strength and ductility and elevated-temperature strength and creep resistance than is found in magnesium-Mischmetal-manganese alloys, which have been reported earlier.2-5 The only known attempt to study wrought magnesium alloys containing pure cerium instead of Mischmetal was made by Mellor and Ridley.6 They found that in the form of rolled bars there is a definite, optimum cerium content for creep resistance at 200 °C and that the creep resistance of these alloys at 200 °C is significantly Improved by heat treatment at 550" to 580"C. In the present investigation the compositional variation in mechanical properties of the following alloy systems is presented: I—magnesium-Misch-metal. 2—magnesium-cerium-free Mischmetal. 3— magnesium-didymium. 4—magnesium-cerium. 5— magnesium-lanthanum. Alloys containing predominately praseodymium are not included in this series because of the lack of this material. Experimental Procedures The alloying ingredients used in preparing the alloys described herein are the same as those reported in the earlier paper.' Cerium-free Mischmetal is the rare-earth mixture remaining when the cerium is removed from Mischmetal, which contains all the rare-earth metals as they occur naturally in mon-azite sand, the ore from which Mischmetal is produced. Removal of both cerium and lanthanum from Mischmetal leaves what is commonly called "didym-ium," consisting predominantly of neodymium and praseodymium. Although the composition of the particular batch of each metal used may differ somewhat from the analysis presented previously, these differences are not great enough to warrant repeat- ing the specific composition of each material. The electrolytic magnesium used as the starting material in these alloys has the same typical analysis as that given in the earlier paper.' The alloys were prepared in small laboratory melts applying all the necessary precautions for alloying rare-earth metals with magnesium described by Marande.' Most melts were large enough to cast one 3 in. diam billet 10 in. long. In a few cases, particularly the didymium-containing alloys, the lack of sufficient amounts of the rare-earth metal limited the size of the billet to 6 to 8 in. All billets were scalped to a diameter of 2 15/16 in. and faced to a length of 9 ¼ in. as limited by the size of the extrusion container. The alloys were extruded into ½ in. diam rod on a 500-ton direct-extrusion press using a 3 in. container. The details of the extrusion step are: billet preheat, 925°F (2 hr); container temperature, 900°F; die temperature, 900°F; extrusion speed, 10 ft per min; reduction ratio, 36:1; and percent reduction, 97.3. The lower melting point of alloys containing didymium' necessitated reduction of the extrusion speed to 5 ft per min in order to prevent hot shorting during extrusion. Adequate lengths were cropped from both ends of each extruded rod to assure that all the material used for tests was extruded under uniform conditions. Tensile and compressive properties at room temperature are reported in the several conditions of heat treatment. The ASTM designations are used to distinguish these conditions as follows: T5—Direct age at 400°F (16 hr) T4—Heat treat at 950°F (4 hr) for alloys containing didymium T4—Heat treat at 1050°F (4 hr) for all other alloys T6—T4 + age at 400 °F (16 hr) The lower heat-treating temperature for alloys containing didymium is necessitated by the lower melting point of these alloys. All heat treatments were conducted in electrically heated, circulating-air furnaces. A protective atmosphere containing 0.5 to 1.0 pct sulphur dioxide was used for the high temperature heat treatments. Tension and creep specimens 6 Yz in. long and compression specimens 1½ in. long were cut from the extruded rod. A reduced section of ? in. diam was machined on the tension specimens, whereas on the creep specimens a reduced section of 0.450 in. diam

Jan 1, 1952

By R. F. Mehl, J. K. Stanley

THE recrystallization of cold-worked metals is studied ordinarily by determining the temperatures required for complete recrystallization to occur within a given arbitrary time period, usually within 15 min. to 2 hr. The results obtained are conventionally assembled in a three-dimensional diagram relating this temperature to the amount of cold-work (percentage deformation) and the resultant grain size, though sometimes other modes of representation are employed.1 Such three-dimensional diagrams are not complete, for the number of variables exceeds the number represented. The process of recrystallization is characterized by a time-rate, a fact that is not portrayed upon ordinary recrystallization diagrams. It is known that recrystallization consists in the formation of new nuclei and the growth of these nuclei, a process that continues until the matrix is completely consumed and the original set of grains entirely replaced by the new. This knowledge is old.2 Truly heterogeneous reactions invariably proceed by nucleation and growth; the decomposition of eutectoid solid solutions provides an example about which much is known,3 and freezing, originally studied by Tammann, provides the classic example. Although recrystallization is not a heterogeneous reaction .within the orthodox meaning of the term, the mechanism of the process is the same. As in eutectoid inversion and freezing, it should be possible to study the rate of isothermal recrystallization as a function of time, and it should also be possible to analyze the isothermal reaction curve into the component rates of nucleation and growth that determine them.* Other methods, not employing the rates of nucleation and growth, have been used to represent the rates of such reactions, but these in general have been artificial and have not led to progress.4,5? The theory of recrystallization is not in advanced state; if recrystallization data were obtained, in terms of the rate of isothermal recrystallization, and in terms of the rate of nucleation and the rate of growth of recrystallized grains, and in particular if the temperature coefficients of these rates were measured accurately, an adequate theory should be more readily developed.27 Such an effort requires proper experimental technique, but especially requires suitable methods of mathematical analysis to convert measurements made upon a surface of polish into values for the rate of nucleation and the rate of growth and to combine these into a rate of isothermal recrystallization. These methods are now

Jan 1, 1942

By Granville S. Borden, Frank H. Madison

The fruits of industry are divided between capital, labor, and governments. Capital takes its redemption and remuneration through profits or dividends; labor takes its share through wages; governments take their share through taxes. Each must have a just share, and the question of what is a just share and the question of who shall make the allocation are vital current political and economic issues. Certain political philosophies con- tend that government should take all the fruits and that some dictator or politician should have irrevocable discretion and power to distribute the fruits. Believers in democracy and free enterprise adhere to the view that capital is entitled to redemption and fair remuneration; that labor shall have a fair wage; and that governments shall make equitable levies. But since all human beings, both individually and in groups, are inherently selfish, there are many variable views in regard to the question of what ratios shall be applied in a division of the fruits and who shall have the power to fix these ratios. Perhaps all parties should devote more energy to means of increasing the crop, and not so much time to quarreling over a division of the existing crop. Moreover, all three parties must guard against killing the goose that lays the mineral eggs. For example, if the tax burden becomes oppressive and the taxpayer refuses to carry it, then business stagnates, with consequent unemployment, reduction of profits, and curtailment of government revenue. If a producer assumes the increased tax burden, marginal operations must be closed down, and, again the consequences are increased unemployment and diminished government revenue. Quite often an increase in a rate of tax results in a reduction of government revenue. Perhaps the worst detrimental feature of selfishness and greed on the part of any one of the three distributees of the fruits of industry is the retardation of expansion of the enterprise. Growth means new jobs, more government revenue, better trade, and better standards of living. Explorations and discoveries have resulted in tremendous contributions

Jan 1, 1964

By G. S. Cole, G. F. Bolling

Fluid flow strongly influences ingl structure and the columnar -to-equaaxed transition. Artificial flow patterns siwzilar to the nuturul ones act to induce this transition, while dampening forces act to suppress this transition. It is shown here how simple mechanical forces can be applied to a systerrz in order to induce or slipPvess relative fluid flow and the change both the structure transition and the exact structures obtained. The example used is the effect of slow rotations and oscillations 012 a cooling- ingot (of laboratory scale). The details of rotution and oscillation for various cooling rates, lenlperal~ire gradients, and sizes of ingot are related to other solidzfication variables. THE grain structure of a casting can be changed by altering the fluid motion during solidification. Just how important these changes are depends directly upon the degree to which the fluid motion can be controlled. An early step in understanding the nature and influences of fluid motion was taken by studying natural thermal convection; when a static mechanical device was used to suppress natural flow the result was opposite to that obtained when an electromagnetic device was used to augnlent flow in a pattern similar to the natural one. ''2 Suppression allowed more columnar growth to occur, but "augmented natural convection" brought about an earlier columnar-to-equiaxed transition (CET). Since the solidification of a free ingot must have characteristics somewhere between those displayed during suppression and augmentation, we know that natural convection must influence the CET. Further, since heat transfer in the liquid is always some time-dependent combination of convection and conduction, it can easily be guessed that the temperature gradient in the liquid is the vital factor affecting the CET.1,2 It is obvious that the structure arising from the unadulterated solidification of an ingot, without external influence, is rarely if ever the best possible one. Although the pattern of the natural fluid flow may be considered efficient, the magnitude of the flow and the heat transfer decrease freely from the outset. For a

Jan 1, 1968

By B. A. Rogers

THE etching effect which is produced on a piece of polished iron or steel when it is heated in hydrogen or in a vacuum seems to have been observed first by Osmond,1 who believed that he could distinguish four systems of grain boundaries on a piece of steel which had been heated in hydrogen. In a number of other investigations, samples of pure iron were found, after heating, to have complex networks in which two or three systems of grain boundaries could be detected. It was further noticed that samples that had been polished plane before being placed in the furnace were, after treatment, roughened and undulating over their entire surfaces. From a comparison of the temperature of heat treatment with that of the A 3 transformation, it was concluded that the changed appearance of the samples was definitely related to the latter phenomenon. Certain other deductions were made but these are not of importance here and only observations on the appearance of the samples will be reviewed. Ewen2 heated a strip of polished iron in a vacuum in such a way that one end was maintained at a temperature of 1000° C. and the other at 580° C. On the cooler end there was outlined a simple polyhedral network, and at the hotter there appeared the complex system of lines and the undulating surface characteristic of iron which has passed through the A3 transformation. He found that in going from the cooler toward the hotter end the sample maintained much the same character of surface up to the beginning of the transformed area, but that near this region double grain boundaries were of frequent occurrence. Rawdon and Scott' concluded that the simple type of network brought out by heating a sample of pure iron in a vacuum was of the same type as that developed by ordinary etching methods. They also confirmed the observations of

Jan 1, 1929

By Harold W. Aldrich, Walter G. Scott

The leaching process of the Inspiration Consolidated Copper Co. is based upon the solubility of oxidized copper in sulfuric acid and the solubility of sulfide copper, largely in the form of chalcocite, in ferric sulfate solution. This necessitates the carrying of a rather large amount of iron in solution. The ferric sulfate is regenerated from ferrous sulfate by the oxygen given off at the anode during electrolytic precipitation of the copper. In September, 1924, excavation was started at Inspiration, Arizona, for the construction of a plant to treat 7500 tons of ore per day. When the plant was begun, the fact developed that by a minor change in the height of the overflow on the leaching tanks, 9000 tons could be charged into each tank and treated satisfactorily. This determined the maximum capacity of the plant as 9000 tons per day. The first ore was charged in October, 1926, and there are now available the records of five complete years of operation; namely, 1927 to 1931, inclusive. The original estimate of copper content of the ore to be mined for this plant was 1.19 per cent, of which 0.77 per cent was as oxide and 0.42 per cent as sulfide. From the metallurgical results obtained at the 35-ton pilot plant, it was estimated that a 90.0 per cent extraction of the oxide copper and a 75.0 per cent extraction of the sulfide copper could be made. It was estimated that the tailing would carry 0.182 per cent total copper, resulting in a

Jan 1, 1934

By Joe O. Ledbetter

INTRODUCTION Health physics as a profession really got a significant start during the Manhattan Project of World War 11. The Health Physics Society has recently published its 25th anniversary issue of the journal (June 1980). There was concern over radiation exposures during and after uranium production, especially about radium and its daughter products [Jackson 19401 and, as evidenced by the frequency of articles in the literature, there still is. The reason for this concern was expressed by Harley as "Workers engaged in the mining and pro- cessing of radium-bearing materials are exposed to dusts of the parent, to radon, and to the radon daughter products. In- haled radioactive particulates may be retained in the lung or redistributed to other organs of the body. Relatively minute de- posits of radioactive substances, particularly alpha emitters, have been clearly shown to be the etiological factor in a variety of injuries to industrial and re- search workers. " [Harley 1953] Emphasis in measurements has been placed on radium in water and radon in air, since these are the principal mobilized phases; however, it should be kept in mind that radium-containing particles do become suspended in air as aerosols and radon absorbs in liquids. Much of the uranium mining and production is being carried out aboveground. The principal difference between underground and surface (pit or leach) mining of uranium is the reversal in the relative importance of roles for the types of radiation dose. For aboveground the major radiation exposure is external gamma ray, whereas for underground it is internal alpha; for aboveground, the whole body penetrating is of greater importance than the lung alpha dose. AS a result of the politics involved and the law- suits for any and all diseases as being occupationally- caused, today , more than ever before, the successful performance of the activities connected with uranium production--before-, during-, and after-the-fact-- must include the provision of first class radiation protection. Such protection can be achieved by good measurements, thorough risk evaluations, and adequate controls. Meeting the ALARA (As Low As Reasonably Achievable) philosophy necessarily entails the determination of what is reasonable exposure. The necessary and sufficient elements of radiation safety under the ALARA dictum require a hard look at the dose versus effects data. There are times when the health physicist needs to make decisions of judgement rather than compliance with a well-defined regulation value. In order to facilitate such decisions, the real world must be separated from opinions that are merely artifacts of statistical variation and from the unprovable "what ifs" that are slanted to question the morality of any non-Luddite. UNITS VOCABULARY FOR DOSIMETRY There have been many radiation quantifying and dosimetric units introduced in the past. Fortunately, most of them did not catch on enough to become required knowledge for reading the health physics literature. The unit definitions necessary for our purposes here are the following: -curie (Ci)--unit of radioactivity equal to 3.7 x 10 10 disintegrations per second Webster&apos;s 19711 or the quantity of radionuclide that undergoes 3.7 x 10 nuclear transformations per second. Environmental levels of radioactivity are usually measured in picocuries (10-l2 Ci) per cubic meter for air and in picocuries per liter (pCi/~) for water and sometimes for air. .roentgen (R)--exposure dose of x or gamma rays that gives 1 esu of charge (either sign) to 1 cc of dry air @ STP. The roentgen is equivalent to an energy absorption of 86.7 ergs/g of air [Gloyna and Ledbetter 19691. .rad--radiation absorbed dose of 100 ergs per gram of absorber. The SI unit for absorbed radiation dose is the Gray; 1 Gy = 100 rads. orem--radiation absorbed dose of 1 rad times the quality factor (QF) for that radiation. The QF is 1 for x rays, gamma rays, beta rays, and posi- trons. For heavy ionizing particulate radiation, QF is a function of the amount of energy trans- ferred per unit length of travel, i.e. , the linear energy transfer (LET); the values of QF:LET in keV/um are as follows: 1:<3.5; 1-2:3.5-7; 2-5:7-23; 5-10:23-53; and 10-20:53-175 [Morgan and Turner 19 671 . For radiobiology, relative biological effectiveness (RBE) is recommended for use instead of the quality factor above that is for radiation protection: the RBE is the ratio of the dose of 200 kVp x rays to the dose of radia- tion in question (both in rads) to cause the same

Jan 1, 1980

By Aloys H. Wohlrab

[THE conditions that govern the selection of a suitable type of detachable bit for the small isolated mine, for rock work and tunnel contracting and for the large mine are quite dissimilar, therefore intelligent recommendation of a particular make of detachable bit must involve consideration of many factors. Small, isolated mines may find advantageous a detachable bit that a larger mine cannot afford to use, because of more efficient conventional steel sharpening and steel-distribution practice, but a small mine may of be able to adopt the practice of larger mines because of necessary capital expendites for equipment for detachable-bit sharpening and shanking. The perfect detachable bit, suitable for all conditions, has n yet been developed. CONVENTIONAL DRILL BIT IN USE That drilling speed increases as the hit gauge decreases is well known, but since small-hole drilling is the exception rather than the rule the rate of such increase is probably not so generally recognized. Tests married out by Holman Brothers Limited1 with 7/8-in. show that when bit sizes are reduced from. 1 ½ in. 1 3/8 in., and 1 3/16 in., to 1 3/8 in., 1¼ in., and it&apos; in., respectively, the volume of the hole is15 per cent less and the drilling speed 4q per cent higher. Recent tests by the United States Bureau of Mines2,3in hard, uniform basalt showed that a reduction in average gauge from 2.077 to 1.826 in., a difference of 0.251 in., gave an increased drilling speed of 65 per cent. The limits to which a drill hole may be extended depend upon the loss in gauge. Since the conventional bit with 5° and 14° clearances did not possess sufficient reaming edge to permit the smaller gauge changes that were required for small-hole drilling, experiments were made in bit construction with a view to correcting this deficiency. This resulted in the adoption of the full reaming cross bit (having full Carr characteristics) by some mines.4 In order to drill holes having a minimum taper from the collar to the bottom of the hole, full reaming center-hole cross bits with 90° cutting angles, 5° and I4° wing tapers, forged on 7/8-in. quarter-octagon drill rods, are used in the conventional drill-steel practice at Hollinger. In the steel shop close attention is given to the condition of the dies and dollies, which, combined with a rigid inspection of the finished bit, ensures as nearly a perfect bit as can be forged economically. Shop practices and costs have been discussed in earlier papers.5,6 The method by which the radii for the special dies used for forging bits of different gauge diameter are obtained so that the points and reaming edges cut circles of the same diameter has been discussed by Hibbert.7 REQUIREMENTS FOR DETACHABLE BIT FOR HOLLINGER Under these circumstances, it was apparent that it would be difficult to introduce a detachable bit that could successfully compete with the conventional bit already in]

Jan 1, 1942

By W. S. Cavender

The Round Mountain mining district, Nye County, Ne- vada, was discovered in 1906 on claims owned by Lewis D. Gordon. Initial mining operations uncovered gold veins of spectacular richness, and within a few days of discovery, Gordon sold his controlling interest for some $87,000. From this sale emerged the Round Mountain Mining Co., predecessor of Nevada Porphyry Gold Mines, Inc., the latter destined to become the major property owner in the area. Vein mining in the district continued sporadically into the early 1930s, yielding 9.3 Mg (330,000 oz) of gold plus substantial silver credits from approximately 626 kt (690,000 st) of ore. In addition to the lode deposits, the early miners recognized the placer potential in the alluvial fan material accumulated around the west and north sides of Round Mountain itself. Intermittent placer operations were carried out for a number of years, and in the 1940s and 1950s, Round Mountain Gold Dredging Co. worked the placers under a lease from Nevada Porphyry Gold Mines. The last placer operation terminated in 1959 when it, like some of its predecessors, proved uneconomic. Total placer production for the district is estimated at 3657 km (4 million yd) of gravel containing 59 Mg (210,000 oz) of gold and possibly 2.0 to 2.3 Mg (70,000 to 80,000 oz) of silver. Round Mountain is a small hill situated on the east flank of the Toquima Range in central Nevada. The hill is com- posed of relatively flat-lying Tertiary rhyolitic ash flow tuffs, which overlie Paleozoic metasediments and Cretaceous granites. Throughout the surrounding Round Mountain mining district, most of the known gold ores occur in the tuffs, although the metasediments and granites are also mineralized. Mineralization is structurally controlled, principally by a series of northwest-trending shears and shattered zones. Vein, stockwork, and disseminated ores occur, usually containing simple quartz-pyrite-gold mineral assemblages. The gold itself is electrum, having a silver content of 30% to 40%. In September, 1967, Elwood Dietrich, a prospector and mine promoter, obtained a purchase option on the 4452 ha (1 1,000 acres) of mineral rights held at Round Mountain by Nevada Porphyry Gold Mines. The original option had a buy-out price of $1 million and was established through Dietrich&apos;s friendship with officers of Nevada Porphyry. In April, 1968, Dietrich conveyed his option to Ordrich Gold Reserves Co., a partnership created by a group of west coast investors, mostly employees of the airline industry. There- after, Ordrich invested considerable funds in trying to test and develop the property, but soon recognized the need to seek financial and technical support from the mining industry. In December, 1968, Dietrich contacted Wayne Cavender, then Regional Geologist, Southwest, for Copper Range Exploration Company (CRX) in Tucson, Arizona, and made a data presentation. Shortly thereafter, Cavender was appointed Manager of Exploration and Chief Geologist for Copper Range Co. (parent company of CRX), New York City, and he asked C. Phillips Purdy, CRX Regional Geologist, Northwest, to make an initial property examination. Purdy&apos;s one-week field study took place in March, 1969, and resulted in a recommendation that CRX pursue its investigation of the property. The presence of low-grade gold mineralization in both the alluvial gravels and in the bedrock was verifiable, but the placer was deemed to have the greater immediate economic mining potential. At that time, gold was in the $1.41/g ($40 per oz) price range. Working from Purdy&apos;s information, Cavender decided to attempt acquisition of the property, and the first in a long series of negotiations was initiated with Ordrich. Basically, CRX felt that the placer had a promising potential for several reasons, including (I) past operators had recovered free gold but not the gold contained in the pebble fraction of the gravels; (2) past operations appeared to have been ineffectively designed or managed and not costefficient; and (3) the price of gold appeared to be poised for an upward move. Negotiations with Ordrich were prolonged and difficult, with CRX competing against several ma* mining companies, but finally an agreement was reached, effective June I, 1970. Gold was then back to $35. It is believed that, in

Jan 1, 1985

By H. Sigurdson, C. H. Moore

Extensive studies have been carried out on electric furnace and blast furnace slags obtained in the winning of iron from its ores. These slags normally consist of elements of the gangue minerals present in the ores, as well as the added flux materials. In consequence, melts of CaO, MgO, Al2O3 and SiO2 can be considered as representing typical slag compositions. When a slag of this composition cools, it usually crystallizes according to predictions possible from an equilibrium diagram of these constituents, providing the melt is not undercooled to form glass. The melt is either viscous or fluid, depending upon the ratio of binary cations to silica, and crystallizes easily or forms a glass for the same reasons. If the melt is not overheated so that carbides of the metal components of the slag are formed and if the composition of the slag is so adjusted that it has a high fluidity, liquid equilibrium is attained and the slag can be held in a liquid state for extended periods of time. Upon tapping, the slag crystallizes into minerals, the type and proportion of which are determined by the melt composition. Since equilibrium is attained, the holding period is not critical. In melts containing a large increment of titanium, however, the normal slag procedures are not applicable. Titanium, as one of the atomic transition elements, is, at elevated temperatures, capable of being reduced to form metalloid compounds much more readily than the refractory oxides present in normal slags. In consequence, an oxide melt containing titanium never reaches equilibrium in a reducing environment, but continues to shift its composition until cooled. If melts of this nature are cooled and samples submitted to metal-lographic and X ray analysis the course of reaction and crystallization in this type of slag can be determined. Preparation of Slag The slags investigated fell into the system CaO-MgO-TiO2-Al2O3-SiO2 and were produced from ilmenite ores reduced by carbon in an electric furnace. Since the equilibrium series1 and the laboratory smelting of ilmenite2 are described in two of the accompanying papers, detailed description of the smelting procedure is not required here. However, certain essentials must be mentioned. Two types of melts were used to produce slags studied in this investigation. The first series of smelts made to determine proper flux addition were produced in a 4 lb Ajax induction furnace. The charge, consisting of ore with the proper flux addition, was heated in a graphite crucible until fluid, held fluid for a sufficient time period to obtain 1-5 pct FeO content, and poured. Because of the small size of the charge only the final sample of these melts could be examined. In the melts made in the 50 lb arc furnace, however, grab samples taken at 10 min. intervals between time of initial melting and final pouring were available for examination. These samples allowed a much clearer picture of the course of reaction and crystallization. amounts of ferrous oxide and reduced titanium compounds is opaque to transmitted light. Therefore, all petro-graphic studies had to be made on polished slag sections. A representative sample of slag was cut or broken, mounted in a thermosetting plastic, ground flat using 400 grit silicon carbide, the coarse scratches removed with 600 grit silicon carbide and polished on billiard cloth using levigated alumina. Rouge was avoided because of the entrainment of the red particles in pores in the slag, causing a possible confusion with some of the mineral phases. In order to prevent sample projection above the plastic surface red bakelite was used to hold the sample, and backed up with clear lucite. In this manner sample labels could be permanently retained in the mounting. The polished samples were examined on a Bausch and Lomb metallograph at magnifications of 250 X, 500 X, 1000 X and 1800 X. The instrument was equipped for examination of specimens under bright field illumination and with crossed nicols. A magenta tint plate to aid in color tone differentiation was also used. Petrology of Slags In order to determine the composition and mineral relatinos of a previously unreported system petrologically, it is essential that the starting composition, reaction temperature and final composition be known. The chemical composition of the ilmenite ore used in these smelts is given in Table 1, and the complete analysis of a typical high titanium, low iron slag is given in Table 2. In the winning of TiO2 from ilmenite by a smelting process it is necessary to produce a slag which will melt at an economically feasible temperature, remain molten as the iron is removed by reduction, be fluid enough to be readily removed from the furnace, contain a high percentage of TiO2 and a low percentage of reduced titanium com-

Jan 1, 1950

By T. H. Weldon, L. V. Whiton, R. R. McNaughton, J. H. Hargrave

Oxygen enriched air is being used quite extensively in the metallurgical plants of The Consolidated Mining and Smelting Co. of Canada, Limited, at Trail, B.C. The oxygen used for this purpose is a by-product from the Company&apos;s chemical plants located in the area. Most of the ore treated in the Trail metallurgical plants comes from Com-inco&apos;s Sullivan Mine at Kimberley, B.C. At Kimberley the ore is milled to produce lead and zinc concentrates which are shipped to Trail for further treatment to metal. One section of this paper deals with the use of oxygen enriched air in the suspension roasting of the zinc concentrates. In this process the concentrate is calcined for leaching preparatory to electrolytic recovery of the zinc. A second section of the paper describes the use of oxygen enriched air in operations at the lead smelter. There oxygen enriched air is used in the blast to the lead blast furnaces and in the slag fuming furnace which recovers the lead and zinc contained in lead blast furnace slag. The final section of the paper outlines the precautions necessary for the safe use of oxygen enriched air in any plant operation. The Use of Oxygen Enriched Air in the Suspension Zinc Roasters The suspension roasting of zinc concentrate developed at Trail, B.C., has been described in AIME Vol. 121, "The Electrolytic Zinc Plant of The Consolidated Mining and Smelting Company of Canada, Limited" by B. A. Stimmel, W. 11. Hannay and K. D. McBean. Since the publication of that paper, the use of oxygen enriched air in suspension roasting has been introduced as regular practice with marked advantage. The relative importance of a specific advantage may vary with changing conditions, but, in general, it may be stated that improved operation has been achieved at increased capacities. Suspension roasting is carried out at Trail in converted standard 25 ft diam Wedge roasters. The 2nd, 3rd, 4th and 5th roasting hearths have been removed and the drying hearth covered over. Drying of the concentrate is done on the drying hearth and the 1st roasting hearth. The dried concentrate, after any lump&apos;s have been broken up in a ball mill, is fed to a single burner located in the upper part of the combustion chamber. Oxygen is introduced at the burner fan along with the gases from drying, returned combustion gases from the waste heat boiler outlet and the required amount of new air. Up to 60 pct of the concentrate settles out on the 6th roasting hearth, the rest passilig out of the roaster. The product collected in the waste heat boiler is finished calcine, but the dust collected in the cyclones after the boilers is returned to the base of the combustion chamber where the sulphate is decomposed. Gases from the c&apos;yclones go to a Cottrell precipitator. The discharges from the 7th roasting hearth and the waste heat boiler are combined with the Cottrell dust to give the finished calcine. Following small scale tests started in 1933, oxygen enriched air has been used continuously in the suspension roasting of zinc concentrate in Trail, beginning in 1937. A significant factor in promoting its use in this operation was the availability of by-product oxygen from the Company&apos;s near-by Chemical and Fertilizer Division. To-day it is standard practice at Trail to use oxygen enriched air for zinc concentrate roasting. The most important requirement in roasting a zinc concentrate for an electrolytic plant is that the zinc in the calcine should have maximum solubility. It is also desirable at Trail that the gas produced for the manufacture of suhhuric acid should have a ~naximum concentration of SO2 and that a substantial recovery of waste heat from the gas be achieved. High solubility of zinc requires that the sulphide sulphur and zinc ferrite in the calcine be kept low. These are both functions of temperature and time, with formation of zinc ferrite also dependent on contact between the iron and zinc particles. One of the inherent advantages of suspension roasting is that minimum time and contact are achieved. The limit on temperature is imposed by the fusion point of the concentrate and not by the need to control zinc ferrite formation. Operating temperatures are normally maintained within the limits of 1725" and 1850°F. A relatively low zinc sulphate in the calcine is required at Trail, and this results from discharging the calcine from the high sulphur dioxide atmosphere at a temperature above 1600°F.

Jan 1, 1950

By W. L. Fink, R. S. Archer

THIS paper describes results obtained on aluminum-beryllium alloys and aluminum-beryllium-copper alloys in the preparation of which aluminum of 99.95 per cent. purity was used. The constitution and structure of the high purity binary alloys are given. The aluminum-beryllium eutectic occurs at 0.87 per cent. beryllium and 645° C. The solid solubility of beryllium in aluminum at 631° C. is 0.05 per cent. beryllium, and at room temperature is less than 0.013 per cent. beryllium. The densities of the alloys are substantially the same as the values calculated on the assumption that the densities of the elements are not changed by alloying. All of the alloys age-harden at room temperature after a solution heat treatment, and the chill cast aluminum-beryllium-copper alloys age-harden at room temperature without a prior solution heat treatment. Hardness and tensile properties are given. Salt spray corrosion tests on sheet specimens are described. It is shown that beryllium does not lower the corrosion resistance of aluminum to salt spray provided the alloy has received a solution heat treatment. COMMERCIAL POSSIBILITIES OF BERYLLIUM ALLOYS Beryllium has certain properties such as low density, high hardness, good corrosion resistance, low thermal expansion and fairly good electrical conductivity, which would indicate that it is worthy of consideration as an ingredient of light alloys. It was not until recently, however, that beryllium could be produced with sufficient ease to encourage research along this line. The production of beryllium by electrolysis from a fluoride bath has now developed to the stage where it could be used commercially if there were sufficient demand for the element. Claims made in certain newspapers and technical articles in regard to the strength and corrosion resistance of the aluminum-beryllium alloys are not justified by experimental results. Moreover, beryllium is an expensive metal ($200 a pound at the time this work was done) and, on account of the nature of its ore and the consequent difficulty of its extraction, it will in all probability continue to be a relatively expensive metal, although the cost would undoubtedly be a great deal less than $200 a

Jan 1, 1928

By O. W. Ellis

The question of the influence of gases upon the properties of copper has received the attention of a number of investigators, among whom Sieverts,&apos; Iwase,2 Lobley and Jepson3 stand preeminent. Solubility of Gases in Copper Sieverts and Iwasé concerned themselves with the solubility of a variety of gases in the metal in the solid and liquid states. They determined the absorption coefficients of these gases and in all cases found a sharp change in solubility at the melting point of the metal. In this respect they disagree with Lobley and Jepson, who have based their opinions upon the appearance of small ingots of the metal which had been fused in an atmosphere of one or other of three gases and had then been rapidly cooled, while surrounded by gas, to the freezing point (rate—possibly 30" to 60" C. per sec.). The ingots that had been fused and cooled under nitrogen and carbon monoxide were free from blowholes and it was assumed that these gases were not absorbed in amounts much in excess of those which would dissolve in the solid metal; the ingots similarly treated under hydrogen were full of blowholes and it was assumed in this case that gas was ejected on solidification of the copper. The effect of varying the rate of freezing upon the character of the test ingots was not examined by these investigators; otherwise, it is felt, their views might have been subject to modification. Sieverts&apos; most important contribution is that the solubility of a gas in any metal is proportional to the square root of its pressure or concentration. Knowing then the absorption coefficients of the various gases in copper, it should be possible to determine the analysis of the

Jan 1, 1929

By Robert V. Pierce

In the last few years, much study has been devoted to increasing stoping efficiency. The reasons for this are shortage of manpower, shorter working hours, operating regulations, and shortages of essential materials. More efficiency in mining methods is needed to offset these adverse factors. In the past, attention has been centered upon haulage, hoisting equipment, mill flowsheets, etc., but recently the spotlight has been focused on the cost of stoping and the cost of handling materia,ls. Scrapers and scraper hoists have thus assumed greater importance. In order to make it possible for certain ore bodies to be mined at a profit, it has been necessary to apply assembly-line practices to the streamlining of mining methods. All cycles of the mining operation must balance, and the sooner broken ore is removed from the working face, the sooner another round can be started. Since the introduction of scraper hoists in metal mines more than thirty years ago, much progress has been made in their design and application. Alert operators are now constantly watching for methods in which to apply scrapers. The saving of: manpower in development work and the changing of mining methods that once employed manual handling of materials are increasing vital wartime tonnages. Essential ores from newly discovered ore bodies are moving rapidly from stopes to reduction plants—because it is now possible to develop an ore body and place it in production with a minimum of manpower and development work. Today, speed is one of the prime essentials of mining. Everywhere, there is a concentrated effort to use experienced miners in breaking rock, in timbering, and in carrying out the various phases of mining that require many months of training. Much effort is being made to mechanize the working places because experienced men naturally prefer to work where the majority of materials are handled mechanically. In line with this policy, many new men are being taught the details of scraper work, because even green men can quickly become acquainted with scrapers and thereby release older heads to perform the more skilled phases of mining. In some places it has been found economical to change from .one system of stoping to another that more readily allows the application of mechanical muck-handling equipment. Where blocks are worked faster, the cost of materials, time, and labor is cut drastically. This favorable situation allows more manpower to remain on straight breaking and timbering—or straight production mining. Moreover, when blocks are mined faster, more floors can often be mined vertically before the mucking or wheel floor is moved. This results in several direct savings. There are cases where it has been proved that by working a given block faster more area, longitudinally or vertically, could be mined at one time, thus permitting the reduction of development cost. (Fig. I.)

Jan 1, 1943

By R. S. French

The purpose of this paper is to present data that have been obtained during the past two years concerning the effects of prior cold-work and temperature and time of anneal upon the recrystallization and grain growth of 70-30 cartridge brass. It was desirable to study certain of these phases so that an accurate picture of the principles of the subject could be shown. The work is not intended to provide explicit annealing data, but to provide material examples that may help to clarify analogous problems concerning this alloy. Specifications often set limitations upon the grain size of annealed materials because of the importance of grain size upon subsequent manufacturing operations. It was, therefore, worth while to study the variables that affect the recrystallized grain size of this material. C. H. Mathewson and A. Phillips,l W. R, Webster,2 and others have presented annealing characteristic curves of this alloy. A recent typical curve presented by R. S. Pratt3 is shown in Fig. I. The tensile properties and grain sizes are shown as functions of the annealing temperature. Such curves serve as a useful guide in determining the physical properties of annealed material, but as they are made generally under carefully controlled laboratory conditions they do not indicate the performance of metal annealed in a mill muffle, where such conditions as amounts of metal, heating time and temperature may differ. Study of the effect of time and temperature upon grain growth and subscquent recrystallization was made with a coil of metal having the following analysis: 70.04 per cent copper; 0.007 lead; 0.007 iron; 0.00 tin; 0.00 silicon; 0.001 nickel; 0.000 phosphorus; balance zinc. The sample coil was obtained from metal that had been rerolled from hot-rolled mill stock, and was received at 0.228-in. gauge, soft, with a grain size of 0.125 mm. This material was then rolled 43.5 per cent to 0.129-in. gauge and annealed to a 0.053-mm. grain size. In this condition, samples were cut and used in all of the experimental work reported in this paper. Time The first study was of crystal growth at a constant temperature over a moderate length of time. Material was cut from the stock coil at 0.129-in. size and rolled 75 per , cent hard to 0.032-in. gauge. From this piece small samples were cut M by 2 in., suitable for grain-size determina.tions. Twelve samples were placed in an electric furnace uniformly across the width, approximately an inch from the floor. A thermocouple was wired to the center sample, so that the approximate metal temperature could be followed. At various

Jan 1, 1944

By Frederick Rhines

THE investigations of Wyman1 have demonstrated that copper deoxidized with several of the commonly used agents that confer immunity to ordinary hydrogen em-brittlement can still be embrittled if it is annealed alternately under oxidizing and reducing conditions. During the oxidizing cycle, oxygen diffuses into the copper and frequently deposits a subscale composed of the oxide of the residual deoxidizing agent. Upon subsequent reduction with hot hydro-gen, the copper becomes ruptured along the grain boundaries to a depth sharply limited by the previous penetration of oxy-gen as delineated by the inner boundary of the subscale. Obviously the sensitivity to this kind of hydrogen embrittlement is engendered by the introduction of oxygen during the oxi-dizing anneal, but beyond this the mecha-nism of the process, and hence the controlling factors, remain obscure. There are several possibilities: (I) oxygen dissolved in the copper matrix of the subscale may, upon cooling prior to the hydrogen anneal, precipitate as cuprous oxide which is subse-quently reduced by hydrogen as in the familiar case of hydrogen embrittlement; (2) oxygen in solid solution in copper may itself confer susceptibility to embrittlement by hydrogen; (3) the normally refractory oxides such as those of aluminum, silicon and titanium may themselves he reduced by hydrogen when in contact with copper; or (4) the precipitated oxides of the sub-scale may be complex compounds such, perhaps, as Si02-Cu20, which are partially reduced by hydrogen. These possibilities have been examined, and it has been con-cluded that the first three and possibly the fourth are operative collectively or indi-vidually under more or less predictable conditions.

Jan 1, 1940

By H. M. Hobart

THIS paper deals principally with investigations undertaken by the Welding Research Sub-committee of the Welding Committee of the Emergency Fleet Corporation. The general object of the investigations has been to extend the use of welding in the construction of merchant ships and, specifically, to provide a definite basis for obtaining the best economy and efficiency in employing welding in place of riveting in the construction of the hulls of such ships. Composition of Ship-plate Steel The chemical composition of the steel employed in such hull construction varies with the thickness of the plates. Through the courtesy of Mr. H. Jasper Cox of Lloyd&apos;s Register of Shipping, the following information may be given concerning the kind of steel plate employed in American Shipyards in 1918 for the hull construction of merchant ships. Lloyd&apos;s requirements do not relate to the chemical composition. They require a tensile strength of 58,000 lb. per square inch (40.75 kg. per sq. mm.) for their lower limit and 72,000 lb. per square inch (50.59 kg. per sq. mm.) for their upper limit. For the information of the Committee, Lloyd&apos;s obtained from their surveyors at various works data of the carbon content, which is as follows:

Jan 2, 1919