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By Willard R. Jillson

Within the last ten years Kentucky has become celebrated for its low-sulfur bituminous coals. Prior to this time, many investigators had discnvered the abundance of this coal but the fact was unknown to the general public until the last extension of Kentucky's mountain railroads' was completed. The coals of. Kentucky are, broadly, separated into two geographic units—the eastern and the western coal fields. On a basis of their sulfur content these coal fields fall into three units, which are indicated on the accompanying map, by numbers, 1, 2, and 3. The area marked 1, the very southeastern part of the state, shows the lowest sulfur, all coals being averaged. In this field the maximum is 1.04 per cent. and the minimum as low as 0.68 per cent.—both averages and not individual analyses, which would of course show much greater variation. Included in this group are the following counties: Lawrence, 0.87 per cent.; Martin, 0.75 per cent.; Johnson, 0.73 per cent.; Magoffin, 0.87 per cent.; Floyd, 0.88 per cent.; Pike, 0.68 per cent.; Knott, 1.04 per cent.; Perry, 0.77 per cent.; Letcher, 0.80 per cent.; Leslie, 0.70 per cent.; Harlan, 0.79 per cent.; Knox, 0.86 per cent.; and Bell, 0.92 per cent. The total average sulfur content for these thirteen counties is 0.82 per cent. Bordering the restricted low-sulfur field of eastern Kentucky is the No. 2 belt (slightly darker), 'which is commonly known as the western border of the eastern coal field. Here the maximum sulfur is 2.91 per cent. and the minimum 1.05 per cent. Again these are averages and not individual analyses. The counties in this group are: Greenup, 2.60 per • cent.; Boyd, 1.67 per cent.; Carter, 1.07 per cent.; Morgan, 1.40 per cent.; Wolfe, 1.83 per cent.; Lee, 2.93 per cent.; Breathitt, 1.85 per cent.; Owsley, 1.09 per cent.; Jackson, 1.06 per cent.; Rockcastle, 2.30 per cent.; Clay, 1.09 per cent.; Laurel, 1.08 per cent.; Pulaski, 2.24 per cent.; Whitley, 1.05 per cent.; McCreary, 1.50 per cent.; and Wayne. The sulfur percentage average for this area including fifteen important counties is 1.65 per cent. In the western Kentucky field, the great increase in the percentage of sulfur is at once apparent. Ohio County with 3.78 per cent. is the highest and Hancock with 2.87 per cent. is the lowest. The percentages by counties is as follows: Hancock, 2.87 per cent.; Henderson, 3.22 per cent.; McLean, 3.27 per cent.; Muhlenberg, 3.31 per cent.; Hopkins,

Jan 1, 1920

By Frederic E. Carter

THE gold, silver, copper alloys have been the subject of several fairly complete investigations by Jänecke, Sterner-Rainer1 and others, and indeed it would seem as if almost too much labor had been expended on them when one thinks of the numerous other ternary alloys calling for more light; however, the combinations of the three metals are actually so widely used in jewelry that they merit perhaps the work done on them. There are a few properties of importance and interest not treated by the authors mentioned which the writer investigated some little time ago, and therefore he has ventured to put on record the results of some of his tests made at that time. He has chosen, as being the two series of most importance to the jeweler, only the 14 and 18-kt. golds, so the subject is by no means so inclusive as that previously treated. As stated, this paper is merely a record of tests made in a practical manner on two useful series of alloys, and is not at all a critical study of their properties. 14-KARAT ALLOYS These alloys are important because they are the most generally used in 14-kt. jewelry; by changing the proportions of silver and copper there are obtained all shades of color from the green of the alloy containing gold and silver but no copper, to the red of the alloy containing gold and copper but no silver. Many 14-kt. gold alloys are made with the addition of zinc to the three metals mentioned here; the added metal does not appreciably alter the color of the alloy nor has it, in general, much effect on the working properties; it may, however, prove useful as part of the zinc added may act as a deoxidizer and render the alloy free of gas. It is not a necessary addition because with proper precautions all the 14-kt. gold alloys containing only silver and copper in addition to the gold can be made free of gas and capable of being cold rolled without cracking. The alloys in which approximately equal quantities of silver and copper

Jan 1, 1928

By E. D. Fields, M. C. Tippett, S. W. Sayers

The Copper Canyon and Copper Basin properties of Duval Corp., in Lander Co., have been recently added to the list of porphyry copper mines in Nevada, marking the first new copper open pit operations in this state in 15 years. Ore is processed in the 4000 tpd flotation mill at Copper Canyon, with some copper being recovered by dump leaching. The ore from Copper Basin, 10 miles northeast of the Canyon, is trucked to the mill for concentration. Cost of developing the properties is estimated at $22 million. It was recognized at an early stage of exploration that the two deposits were quite different. Continuity, mineralogy and grade of ore are much more uniform in the Canyon than in the higher grade, pod-like deposits in the Basin. The fundamental difference between the two areas is that the Canyon mineralization is dominantly hypogene, whereas the Basin ores are secondarily enriched.

Jan 3, 1968

By W. C. Schroeder, A. A. Berk

Practical experience has shown that at elevated temperatures solutions containing sodium hydroxide may attack stressed steel in a manner that cannot be explained in terms of ordinary corrosion. Because the ductility of the metal has been greatly reduced during the reaction, the entire phenomenon is usually called "embrittlement." Thus, after several years of operation caustic evaporators have been so badly embrittled that rivets could be cracked off with the blow of a hammer. Since fine intergranular cracks are almost always present in the zone of fracture, it has often been assumed that a process of selective corrosion in grain boundaries was responsible for the failure, although this has not been clearly proved experimentally. Concentrations of sodium hydroxide below those necessary for the uniform, rapid attack of the steel surface are reported to be most effective in producing embrittlement2, 3. In the operation of steam boilers a similar type of failure has been found, mainly in riveted seams or other capillary spaces where the solution may concentrate and where high stresses may also exist. It is believed that in such localized areas the dissolved solids may reach a value many times the few hundred parts per million prevalent in the body of the boiler. While this type of boiler failure has been the subject of investigation for a period of 20 years1, an understanding of its mechanism and a rational basis for complete protection have not yet been secured. To procure this information the present investigation was

Jan 1, 1936

By Arthur C. Simmons

Production of oil within the state of Pennsylvania in 1940 was slightly more than the 1939 total, and this increase was due entirely to the new flush Music Mountain field south and west of the main Bradford pool. The influence and magnitude of Music Mountain production will be separately described, inasmuch as it is an important producing unit within the state. Production Bradford Field The production listed herein for Bradford field includes only the part of the field that is within the state of Pennsylvania. Approximately 4000 bbl. per day, or 10 per cent of the total Production of Bradford field comes from Cattaraugus County, New York, and should properly be attributed to production obtained within the New York state area, although locally and economically the Bradford field, situated both in New York State and Pennsylvania, is included as a single statistical unit. The 1940 average production in the Bradford field was 34,831 bbl. per day, as compared with a daily average in 1939 of 35,340 bbl., or a decrease from 1939 of 509 bbl. per day. The decrease in production from the Pennsylvania portion of the Bradford field would have been more pronounced if a portion of the crude from the Music Mountain field were not included with the statistics for Bradford field. The decline can be attributed largely to the fact that more properties of lower average recovery were being drilled in 1939 and 1940 than in previous years, and apparently a subnormal amount of drilling occurred in 1938 and 1939, when about 2100 wells were drilled each year. The full effect of the 1940 drilling is not felt immediately and undoubtedly will affect the producing period of 1941. It appears probable that the water-flood area in the Bradford field has reached a definite peak unless some unusual economic condition should cause abnormal prices and an excessive rate of development such as occurred in 1936 and 1937. Virtually all of the production in the Bradford field was obtained by water-flooding methods, as natural or stripper wells are uneconomical and air and gas repressuring have not proved so efficient as water-flooding as a secondary recovery method. Central and Southern Pennsylvania Central and southern Pennsylvania produced a total of 4,604,763 bbl. of oil during the calendar year of 1940; that is, an increase over the 1939 total of 166,728 bbl. The daily average production was 12,581 bbl., or an increase over 1939 of 422 bbl. per day. Table I includes the total oil production for the state of Pennsylvania for the years 1937 to 1940, inclusive, and the daily average for each of these years. It is impractical to make a complete subdivision by districts, consequently the only segregation is the production from the Bradford field (within the state of Penn-

Jan 1, 1941

By John C. McDonald

This report is a continuation of an earlier one with a similar titlell to which the reader is referred for such details of procedure as do not appear here. A brief summary will be given of the objects and methods of the research at this time. It was pointed out in the previous paper that properties of magnesium alloys, as reported by different workers, often differ. This was thought to be due to differences in the preparation of the specimens tested. The ideal way to compare alloys would be to prepare each of them in so many ways that reasonable assurance would exist that the best properties of each alloy had been developed. The alloys would then be compared on the basis of these properties. The treatment actually given the alloys of these studies is necessarily a compromise with completeness. Nevertheless, enough treatments have been given so that a considerable degree of assurance exists that the properties obtained are representative of the alloy as such, and not merely of the manner in which it was worked and heat-treated. Procedure The alloys were cast in the form of cylindrical ingots, which were extruded into bar before being rolled. Some of the ingots were made in 2-in. diameter molds whereas all of the alloys of the previous paper were cast in 4.in. molds. For the larger ingots, the extruded bar was 2 by 0.140 in.; lor the 2-in. ingots, it was I by 0.100 in. Preliminary work indicated that strip rolled from both sizes of the bars would have substantially the same properties. The bar was rolled at some temperature in the range 400' to 800°F., for a total reduction of 50 per cent. The temperature and reduction per pass were so selected that no cold cracking occurred, but were such as to leave the metal in a semihard condition. The hot-rolled metal was annealed at several temperatures in the range 400' to 800°F.; it was also cold-rolled, and given solution and aging treatments. Two standard test bars corresponding to each treatment were pulled in tension, and the average was obtained. Twelve treatments, in all, were given each alloy. The properties of the annealed specimen having the highest percentage of elongation were selected to represent the alloy in the annealed condition. The properties of the cold-rolled specimen having the highest yield strength were selected to represent the alloy in the cold-rolled condition. These properties were then plotted against percentage composition by analysis. Smooth curves were drawn among the points, thus graphically averaging the results over the entire range studied. The percentage of elongation in the cold-rolled state was not plotted, since it was always low, and varied in an irregular manner with composition. Alloys Studied Magnesium-calcium Alloys.—Fig. I presents the results on the alloys of the rnag-

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 For the most part, students of engineering colleges have had their interests in applied science awakened at a relatively early age. Manyof 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 non-college 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 inter. ested 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 ,de of the beneficial results to be obtdned 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 John L. Boardman

Because of the attention that has recently been given to the health and safety of miners by various organizations such as the A.I.M.E., The American Congress, Mining Section, National Safety Council, as well as the Bureau of Mines and various state mining departments, your committee on health and safety deemed it best to call attention this year to the mine-accident cause that is by far the most important; namely, injuries due to falls of ground, rock, roof and coal. Each of several members of the committee contributed a brief outline of the importance of this accident cause in his district. While these papers were brief, it would require too much time and space to give them in full, therefore we present an outline of each and summation of all. Report of M. D. Cooper, Hillman Coal and Coke Co. M. D. Cooper, Division superintendent, Hillman Coal and Coke Co., Pittsburgh, Pa., contributed the following: During the period from 1930 to 1939, accidents from falls of roof in bituminous mines average 54.3 per cent of all accidents. In mechanized mining, there is a tendency toward reduction in this class of accidents because the operator of the machine is usually at a distance of 10 to 20 ft. from the face, whereas in hand load- ing the miner is close to the face during most of the shift. No doubt the use of aluminum and light steel beams supported at regular intervals by jacks, a common practice in mechanical mining, has contributed to the favorable record so far developed. Report of M. H. Fies, De Bardeleben Coal Corporation Milton H. Fies, Vice-President, DeBar-deleben Coal Corporation, Birmingham, Ala., says: With reference to the types of mining, it is suggested that a clear understanding be had as to the character and thickness of the directly overlying strata, with especial consideration to the strength and in some cases an analysis of it. In coal mining, generally speaking, overlying strata higher in silica than others is stronger. In changing from narrow to wide places, the procedure should be experimental, both as to the width and depth of places and as to the nature of the necessary timbering. Since most of the accidents in coal mining particularly are due to falls of roof and coal, this phase of mining should be attacked with vigor There is no substitute for discipline and, in this connection, under present conditions it is important that cooperation by the labor ornanizations- be sought and that a spirit of fairness prevail. Frequent and thorough inspection of all active working places should be made.

Jan 1, 1943

By J. E. Wilson, F. P. Lebar

TYPICAL of southwestern Wyoming are coal structures that dip from 4° to 17°. Those at the Reliance and Winton mines of the Union Pacific Coal Co. average 91/2 and 15°, respectively, and dip almost directly to the west. By using a hoist for main haulage, a method of mining has been developed whereby four places are driven on the pitch of the seam. Slightly upgrade from the strike at intervals of 300 ft. a two-entry system is driven to the north and to the south. In both fields, which are nongassy, an exhaust system of ventilation is used. Slope, manway, and lower or haulage entries are placed on the intake. Two air-courses and upper or breaking entries are placed on the return. A retreat system of mining is used exclusively. From the opening of its first coal mine, in the year 1868, until 1923, when the Joy loader was introduced into The Union Pacific Coal Company's operations, slopes, aircourses, and manways were driven by hand. Development work was conducted on the night shift or off shift, and the main hoist was used for haulage. The slope was driven down the pitch with crosscuts turned at intervals of 75 ft. and entries at 230 ft. Connections to the workings above were made by driving up the pitch 75 ft. Mule haulage was used to furnish cars to the hand loaders driving planes up the pitch. A sheave was placed at the upper end of the plane with a I¼-in. hemp rope dou- bling around it and having me end attached to the car and the other to the mule. The mulc, pulling downhill, raised to the working face a small wooden car of one-ton capacity. With the introduction of mechanical loading, mule haulage and small wooden cars disappeared and auxiliary hoists, electric locomotives, and steel cars with a capacity of 4 tons were substituted. Development work was done during two or three shifts of the 24-hr. period. Driving of haulage slopes down the pitch by hand continued. Crosscut intervals were changed to Ioo ft. and the crosscuts were driven with shaking conveyors. With the use of a 90° swivel, aircourses and manways were driven up the pitch. Entry intervals were changed from 230 ft. to 300 feet. Mobile loaders of the Joy type were first employed by this company in the year 1923 at Hanna, Wyo. In 1928, two 4-BU Joy loaders were transferred from Hanna to Winton No. I mine, where they were used in driving slopes and entries. At the time of transfer, the machines were about worn out and were not suited to the steep pitch, therefore frequent breakdowns occurred. However, experience justified the belief that the mobile loader was fitted for driving slopes in this field. During 1937 a unit was installed in Reliance No. 7 mine, and during 1939 one in Winton No. 7½ mine. With the introduction of this type of mobile loader, a new era of development began. Speed undreamed of in hand-loading days became a reality. The cost of development down the pitch has been reduced until it

Jan 1, 1942

By Harrison Schmitt

The definitions of the terms commonly used in connection with metamorphism at elevated temperature near igneous contacts are re-examined. As the study of tactite zones associated with igneous contacts progresses, more and more emphasis is put on the localization of the ore by structural forms. The generally early age of the silicates and late age of the sulphides is well established. Postsilicate structural deformation is likely to localize ore bodies. The silicates are often replaced by the ore minerals. we may not be far from proving that the elements involved in the formation of silicate aureoles are merely normal "volcanic" emanations, that silica, lime, magnesia, and alumina, and probably soda and potash, are likely to undergo local transfers only. The work of Newhouse suggests the agents of the formation of sulphides in deposits of various classifications are the volcanic emanations. Introduction The purpose of this paper is to define the terms commonly used in connection with the subject, to briefly review and discuss the broad features of the aureoles, to indicate some of the features lately recognized: to discuss the genesis, and to suggest how the associated ore deposits can best be studied and developed. When developing a subject in mining geology one is soon conscious of the vast amount of pertinent literature and that most relevant ideas, no matter how obscure, have been considered. One can only hope to make some small contribution in point of view, a few confirmatory observations, or, perhaps, suggest a small new idea indebted to the most recent data. It is nearly impossible, also, to give specific credit, and adequate credit, to all the contributors to a given subject. This study, furthermore, was not intended to cover the field exhaustively, nor is the bibliography complete. Definition OF Terms There is much confusion in the use of the broad terms concerned. Needless to say, metamorphism means change of form; metasomatism, change of substance. The term contact metamorphism, however, has been widely misused possibly by a majority of economic geologists and engineers. As originally adopted by European investigators it meant changes effected largely by heat (thermal effects) in the rocks invaded by plutonic intrusives, but did not include those local changes usually at the immediate contact brought about by the addition of substance, i.e., by metasomatism. The term has become clouded. In Europe it has

Jan 1, 1949

By Sherman L. Pease

An inexpensive and relatively rapid method that can be used by field crews is described. Fluid movement is determined by releasing a tracer (dye) in the well at a predetermined level and, after an interval of time, sampling the well fluid at another level. The testing equipment consists of a combined crusher and sampler unit that is run into the well on a wire line. The rate of movement can be calculated from time-volume relationships. Description of Method It is often desirable to determine whether there is occurring any transfer of fluid from point to point in a shut-in well, and, if so, to measure the rate of movement. When it is desired to examine a large number of wells for possible "thief" sands, the time and expense will be considerable unless the method used is inexpensive and rapid. After experimentation with several possible solutions to the problem, the Production Department of the Shell Oil Co., Inc., developed the apparatus described herein, which has proved satisfactory. Routine operations with it can be carried out by field production crews with a minimum of technical supervision and with negligible investment in equipment. The method is based upon releasing a suitable tracer in the well fluid at a known level, and recovering a sample of well fluid at another level after a measured interval of time. Repetition of this process with different time intervals between release and sampling gives the necessary data. For purposes of illustration, the setup for measuring migration of fluid in an upward direction is described in the following paragraphs. The arrangement of equipment is shown diagrammatically on Fig. I. The elements of the combination unit are the tailpiece, the crushing device, the spacer and the sampling device. The lengths of the tailpiece and spacer are varied to place the crushing and sampling devices in the desired positions in relation to the sands being tested. The crushing device breaks the glass bottle containing the tracer when the tailpiece strikes the bottom of the well and the tension on the sand line is slackened. Because of the open construction of the crushing device, the tracer is quickly and completely disseminated in the well fluid. The sampling device is a suction bailer, which obtains a sample of the fluid surrounding the perforated nipple just before the unit is picked up off bottom. The sample is retained in the barrel by the ball valve for examination at the surface. Normally, on the first run into a well, the sample is obtained near the releasing point of the tracer, and thereafter samples are taken near the base of the upper sand if migration is indicated by the dilution or absence of the tracer in the initial sample. The length of the time interval between the releasing of the tracer and the sampling of the well fluid is varied for successive runs, attempting first to establish the rate within limits and then to define it more accurately by additional runs if necessary.

Jan 1, 1946

By G. B. Craig, G. L. Montgomery

A simple technique has been developed which reveals glide dislocations in zone-refined aluminum as etch pits. The technique has been tested quantitatively by making dislocation counts on aluminum single crystals deformed in pure bending. The method has the advantage of being insensitive to the orientation of the surface under examination. A number of etchants which will reveal dislocations in annealed aluminum have been reported.'-' These etchants apparently depend on decoration of the dislocations by an impurity (probably iron) and cannot, therefore, be used to reveal fresh glide dislocations. In addition, it is unlikely that screw dislocations will be etched because of their small attraction for impurity atoms. Amelinckx6 has reported that glide dislocations located along slip traces can be revealed by fluo-rated aqua regia. This work indicated that dislocations themselves, irrespective of decoration by impurity atoms, are responsible for the etch pits. However, as a result of additional etching experiments, Wyon and Marchin7 concluded that dislocations alone are not sufficient to explain the localization of etch pits on slip lines in aluminum using chemical etch-pitting techniques. In addition, their results show that glide dislocations are revealed only on surfaces approximately parallel to a (100) axis and that not all slip systems are attacked. These observations have been confirmed by the present authors. The technique described in this article is insensitive to the orientation of the surface, and reveals dislocations on all glide systems. Fig. 1 shows a deformed region in the neighborhood of a scratch. Dislocations can be seen along three slip traces. In the present work, single crystals of zone-refined aluminum are polished for from 2 to 5 min in a chemical polishing reagent held at 100°C, as described by Herenguel and second:' H2Sol 60 pct H3PO4 30 pct HNO3 10 pet The samples are then coated with a thin oxide film by annealing in air at 450°C for 1 hr and cooling in the furnace. After deformation, dislocation etch pits are developed by immersing the specimen in the same polishing solution which is now held at a temperature of 50°C. The formation of small hydrogen bubbles indicates that etching has occurred. The sample is immediately removed from the solution. Prolonged etching results in enlargement of the pits and, in regions of high dislocation density, the overlapping and loss of resolution of individual pits. It is the experience of the authors that contact with iron will ruinously contaminate the reagent. With careful etching, dislocations separated by half a micron can be resolved optically and the method has been shown to be sufficiently sensitive to reveal dislocations produced during the pre-easy glide region of deformation, Fig. 2. A few examples of glide-dislocation configurations, as revealed by this technique, are shown in Figs. 1 to 4.

Jan 1, 1964

By Robert Linton

In 1898, Joseph L. Giroux and J. A. Snedaker organized the Pilot Knob Copper Co. and began developing the Pilot Knob mine at Kim-berly, Nev., for high-grade copper ores, carrying good gold and silver values, that the formation had disclosed. At that time the nearest railroad was over 150 mi. distant. The high-grade ores did not prove to be extensive at this point—at least to the depth (240 ft.) to which the work was carried—but development of neighboring claims indicated extensive deposits of sulfide porphyry ore of concentrating grade lying at shallow depth, and deeper deposits of direct-smelting oxidized ores occurring in limestone near the limestone-porphyry contact. The properties passed through the hands of several organizations, with only meager development, until acquired in 1913 by Consolidated Coppermines Co., whose holdings now comprise 3480 acres of mining claims in the Robinson district. Since that time development has been prosecuted more actively; and for the purpose of determining the most efficient and economical method of treating the ores, considerable testing work has been done during the past three years, both in the laboratory and in actual mill operations. At first, the shipments were of ore high enough in grade to be profitable even with the long wagon hauls to the railroad and prevailing freight and smelting charges. In 1905, a blast furnace and a concentrator were erected at Kimberly. On account of insufficient ore supply, the blast furnace was never blown in and later was dismantled. The concentrator as originally equipped was operated for only about two months, both because the ore supply at that time was not sufficient and because gravity concentration did not yield satisfactory extraction. The location and arrangement of the mill further entailed high operating costs. In 1908, the Nevada Consolidated Copper Co. began to mill successfully, on a large scale, its sulfide porphyry ores, which are similar in character to the adjacent Coppermines ores. After that time, all of the ores and concentrates produced by Coppermines Company were smelted and a considerable part of the Coppermines low-grade ores concentrated at the Steptoe works of the Nevada Consolidated Co.

Jan 1, 1921

By R. J. Mellen

In a chloridizing roasting and cyanida-tion plant treating a manganese-silver ore, certain experiments pointed out the way to an improvement in roasting conditions by a change in the degree of crushing. The following short article is simply a description of the various changes that were necessary throughout the plant and of the results obtained. There is nothing unusual in these changes but they are of some interest in that they constitute a good many of the alterations usually resorted to in increasing production. In the beginning, the changes were brought about by an experiment that was not successful, but which clearly pointed to means of improving the operation, and is an example of the fact that often experimental work may result in failure and still be of value in arriving at correct fundamentals. This experiment also shows how far a metallurgist can get out of line in his deductions, particularly in a field with which he is not thoroughly familiar. The ore at the plant of Compania Minera Kildun y Anexas is crushed through a 13-in. gyratory, a 3-ft. standard Symons cone crusher and a set of 16 by 42-in. rolls, the latter in closed circuit with two Tyler type 400 screens. The crushed ore is then conveyed to two fine-ore bins. These provide storage and feed for two 6 by 90-ft. kiln roasters, which discharge directly to coolers. The coolers in turn discharge to a 6 by 12-ft. ball mill, where the ore is ground for cyanidation. Laboratory and pilot-plant tests previous to the mill construction had indicated that minus ¼-in. crushing was satisfactory for roasting, although results did not vary greatly with some coarser or considerably finer crushing. The plant was designed for a capacity of 300 tons per day on this basis. After a few months operation, the initial operating problems were overcome and the anticipated milling rate was reached but the results being obtained were not really good. The plant seemingly did not have much excess capacity in any department but the roasting operation was the most critically limiting factor both as to tonnage and the results obtained. If this could be improved there seemed some possibility of improving the total tonnage rate to some extent. Segregation of the calcine into various screen sizes showed that the coarser sizes were not giving the expected recoveries. In all of the laboratory and pilot-plant testing, any limiting conditions as to the percentage of salt used, temperatures, feed rates, etc., had affected the fine material more than it had the coarse, and even in making laboratory tests at this time the mill conditions could not be exactly duplicated. Further laboratory testing indicated that a segregation of the rushed Ore into a coarse and fine product for roasting might result in some improvement in roast-

Jan 1, 1947

By D. C. Jones

The term "coal-mine mechanization" is definable in several ways. In its general application it can mean the use of machines instead of manpower in each of the various mining activities necessary for the production of coal—so that under this definition a mine that uses mechanical coal cutters could be classed as a mechanized mine. Common usage, however, insists that a mechanized mine is one in which machines are used for the entire process of mining or extraction and transportation of the coal. For the purpose of this paper, then, the second definition of "coal-mine mechanization" will be used, and practices employed in mines where the greater part of the production is obtained through the use of mechanical loaders and conveyors will form the basis for this discussion. Physical Contact Hazards If we were to group all the hazards that accompany the use of mechanized equipment in a mine, the predominant class would be that which, for want of a better name, might be termed the "physical contact" hazards; that is, all the sources of danger that lead to accidents through physical contact of workmen with machines. A survey of accidents in a group of mechanized mines indicated that this class of hazards may be responsible for more than half the number of accidents in mechanized mining. For example, of 21 mining-machine accidents at one mine, 14 were of the physical contact type; of 14 loading-machine accidents at the same mine, 8 were the result of physical contact. Certain of these hazards are controllable through the use of guards— a guard over the cutting-machine bits when the machine is being trammed from place to place, or a chain or some similar locking device around the cutter chain, so that an accidental blow or push against the bit control will not cause the cutter chain to move. Other hazards, such as the possibility of a loader operator having his foot crushed by a crawler tread, or a brakeman being hit by a loader boom swung too far to one side while a car is being loaded, might be subject to control through the use of guard devices, but the reduction or elimination of all physical contact hazards by such methods does not appear feasible. Every accident of the physical contact type should he investigated to discover whether guards could have prevented it, but often the only way in which to combat these hazards will be through the awakened consciousness of each workman as to the danger that exists if he indulges in unsafe practices. A good approach to control of accidents in any mine is the establishment of a set of safety rules or operating rules. The intent of such rules is to provide guides far the workmen to follow in the operation of equipment. Frequently the workmen have no regard for such rules, and observance is obtained only through compulsion on the part of management. An interesting development in connection with-the formation of safety rules occurred during a training program for employees in the

Jan 1, 1947

By Harry H. Angst

THE history and efficiency of 40-ton capacity dump trucks for surface waste removal at the New Cornelia opencut copper mine, at Ajo, Ariz., are summed up in this paper. Tabulations of truck performance, together with detailed cost figures, prove the value of truck transportation for certain special operations at a large mine. Emphasis is given to the fact that truck transportation not only reduces the haulage costs but also reduces the breaking ground and shovel-loading costs per ton. The New Cornelia opencut copper mine is in the desert. The climate is ideal for seven months of the year, but the five summer months are uncomfortably hot. The elevation is 1820 ft. above sea level and the annual rainfall is approximately 6 inches. The ore body is a monzonite-porphyry deposit. The waste-rock capping consists of hard rhyolite, conglomerate and porphyry. All the material is hard and cannot be excavated without blasting. The rhyolite and conglomerate waste is very blocky. The weight of the rock in place is 2.16 tons per cubic yard. The average mine production per day is 22,000 tons of ore and 18,000 tons of waste rock, the latter consisting of surface rock and material within the ore body too low in grade to send to the concentrator. The rock is loaded by electric shovels with 4 ½ -cu. yd. dippers. The primary transportation of ore to the concentrator and waste to the dumps is by 30-yd. dump cars and oil-burning steam locomotives; therefore truck haulage of waste is a minor factor of the New Cornelia operation. However, as New Cornelia was one of the first mines to use large-capacity dump trucks for haulage, the results obtained are of interest. EQUIPMENT On the south side of the New Cornelia is a hill rising about 500 ft. above the normal surface elevation, roughly 1000 ft. in diameter at its base, called locally Arkansas Mountain peak. Exploratory drilling in this area developed additional ore that could be made accessible for open pit operation only by moving the mountain face a maximum distance of 400 ft. to the south. The slope of the mountain adjacent to the pit averaged 35°, and the small area involved precluded the use of train haulage for the removal of the 4,000,000 tons of waste estimated above the normal pit elevation. A study of dump-truck haulage at Boulder Dam and San Gabriel Dam led to the decision to use large-capacity end-dump trucks rather than smaller trucks, for the following reasons: 1. The truck would have to withstand the impact of hard, heavy chunks, some of them weighing as much as 10 tons, which would be dumped from the 4 ½ -cu. yd. dipper. 2. The coarse, rocky, abrasive material would soon damage a light truck body. 3. The body of a small truck could not be efficiently loaded with coarse rock.

Jan 1, 1941

By John C. McDonald

This report is a continuation of an earlier one with a similar titlell to which the reader is referred for such details of procedure as do not appear here. A brief summary will be given of the objects and methods of the research at this time. It was pointed out in the previous paper that properties of magnesium alloys, as reported by different workers, often differ. This was thought to be due to differences in the preparation of the specimens tested. The ideal way to compare alloys would be to prepare each of them in so many ways that reasonable assurance would exist that the best properties of each alloy had been developed. The alloys would then be compared on the basis of these properties. The treatment actually given the alloys of these studies is necessarily a compromise with completeness. Nevertheless, enough treatments have been given so that a considerable degree of assurance exists that the properties obtained are representative of the alloy as such, and not merely of the manner in which it was worked and heat-treated. Procedure The alloys were cast in the form of cylindrical ingots, which were extruded into bar before being rolled. Some of the ingots were made in 2-in. diameter molds whereas all of the alloys of the previous paper were cast in 4.in. molds. For the larger ingots, the extruded bar was 2 by 0.140 in.; lor the 2-in. ingots, it was I by 0.100 in. Preliminary work indicated that strip rolled from both sizes of the bars would have substantially the same properties. The bar was rolled at some temperature in the range 400' to 800°F., for a total reduction of 50 per cent. The temperature and reduction per pass were so selected that no cold cracking occurred, but were such as to leave the metal in a semihard condition. The hot-rolled metal was annealed at several temperatures in the range 400' to 800°F.; it was also cold-rolled, and given solution and aging treatments. Two standard test bars corresponding to each treatment were pulled in tension, and the average was obtained. Twelve treatments, in all, were given each alloy. The properties of the annealed specimen having the highest percentage of elongation were selected to represent the alloy in the annealed condition. The properties of the cold-rolled specimen having the highest yield strength were selected to represent the alloy in the cold-rolled condition. These properties were then plotted against percentage composition by analysis. Smooth curves were drawn among the points, thus graphically averaging the results over the entire range studied. The percentage of elongation in the cold-rolled state was not plotted, since it was always low, and varied in an irregular manner with composition. Alloys Studied Magnesium-calcium Alloys.—Fig. I presents the results on the alloys of the rnag-

Jan 1, 1941

By G. C. Gardner

A new correlation of blast penetration in model and operating blast furnaces is presented which overcomes objections to prevzous correlations. It is shown that the tuyere diameter is only of small importance in determining the magnitude of the penetration. The data from operating furnaces correlate satisfactorily with the data from models whose cross section is a segment of a circle. A bubble-shaped gas space called a "raceway" normally exists in front of the nose of a blastfurnace tuyere. The periphery or "wall" of the raceway is well defined and is composed of densely packed charge particles. The blast. issuing as a jet from the tuyere, entrains gas from the raceway, in the usual manner of a jet, as it flows to the opposing wall. There it divides and flows back around the walls to be entrained once more. The blast must, of course, eventually leave the raceway and pass up through the charge column, but before it does it may, on the average, make several circuits of the kind described and in doing so it carries with it charge particles, which, because of their fast and circulating motion, suggested the name of "raceway". A fuller description of the raceway may be found elsewhere."' Here it is only necessary to mention, in addition, the measurement which characterizes its size. If an iron bar is pushed through the opened peepsight of a tuyere, .as far as it will go with ease, it will be stopped by the relatively impenetrable opposing raceway wall arid the distance that the bar has been pushed from the tuyere nose is called the "penetration". This measurement may be of practical importance and has; been the subject, with considerable success, of several attempts at correlation with other variables2-5 as stated in the next section. There is still, however, a serious objection to the most recent correlation,3 which is overcome by the correlation proposed in this paper. It will be shown that the objection is not trivial, in that the new correlation will attribute considerably different importance to the variables affecting the magnitude of the penetration. The data to be treated were made available by Wagstaff and are the same as those used in his correlation. They include measurements taken on small models, in which a cold air blast was used and no combustion occurred, and they also include data from operating blast furnaces at Wheeling and Fairless. The information from the blast furnaces will be shown to be in substantial agreement with those models whose plan views are segments of a circle and which are thus like segments of a blast furnace. First, Wagstaff's most recent correlation3 will be discussed and the objection will be given. Then the new correlation will be developed and its implications considered. CORRELATION OF J. B. WAGSTAFF Wagstaff's correlation is where and D — the penetration D,-the internal tuyere diameter V —the blast velocity in the tuyere

Jan 1, 1961

By A. L. Johnson, S. C. Lyons

A FEW years ago a leading American builder of centrifuges said, "No one uses a centrifuge if the job can be done any other way." This statement was essentially true at that time, not because the basic functional and economic principles involved did not frequently favor centrifugal methods, but rather because so many of the highly specialized features of the mechanical and functional peculiarities of continuous centrifuges had not been fully developed. The idea of using centrifuges in mineral dressing is definitely not new. There are literally hundreds of patents on centrifugal machines and processes for the mining industry. Many of them cover principles that are basic to the functioning of most centrifuges in operation today. In spite of this, until 1935, there were practically no successful applications of continuous centrifuges in the United States in the mineral industry, nor for that matter were there more than a mere handful of such machines in operation in North America in any industry. This was true despite the obvious desirability of machines that could furnish the advantages of high centrifugal settling forces in a continuous operation. The reasons for this are simple, even if not obvious: I. Finely divided solids, when thrown out of fluid suspension under high centrifugal forces, frequently exhibit physical properties (particularly rheological or flow properties) that are markedly different from those they possess when settled out by gravity alone, and machines that are not designed in careful detail to cope with these peculiarities seldom function satisfactorily. 2. Most continuous centrifuges embody a solids-conveying element in the form of a very special screw conveyor. The rotation of this member under conditions of operation calls for drive designs that were not satisfactorily provided until the introduction of the Bird gear unit about 1934. These matters will be touched on later. Continuous centrifuges are now operating successfully in the mineral industry. Some units have singly handled more than 500,000 tons of solids during the past ten years. Generally their operation has been characterized by large unit capacities, complete elimination of labor, minimum supervision, moderate maintenance and power costs. TYPICAL CENTRIFUGE APPLICATIONS Most materials classified by centrifuges are of subsieve particle size. Practically speaking, this means finer than l00-mesh. A unit of measure other than screens is needed in order to consider these products properly. Such a unit is the micron, which is equal to one one-millionth of a meter; roughly 1/25,000 of an inch. The opening in a standard 200-mesh screen is about 75 microns while a 325-mesh opening is roughly 43 microns.

Jan 1, 1947

By William C. Marshall, Frank G. Norris

THE term "total operation" is meant to include problems that cannot be answered from the standpoint of either the blast furnace or the open hearth separately but must be studied by considering the interrelations of these two processes. There are other ways of expressing this idea, such as reference to the blast furnace and the open hearth as an integrated process or by emphasizing the interrelation and interaction of the two processes. Much progress has been made in metallurgy and other fields by breaking complicated processes and reactions into simpler parts and studying each of these intensively. This intensive study frequently is done under the controlled conditions of the laboratory experiment. The entire process is understood better by this specialized study of each of its parts. This procedure is so satisfactory that an understanding of unit operations is a fundamental requirement of chemical engineering. Much discussion of the open-hearth process is in terms of one heat or one furnace. By this is meant that the conclusions apply to one furnace, wherever it may be. Furnaces seldom occur singly; they are located in groups and these groups are located in steel plants having characteristic blast-furnace equipment. Problems that are affected by the number of furnaces operating, by the number of blast furnaces in the plant and by the fact that the open hearth shop is dependent on the blast-furnace capacity rather than on its own needs for the amount of iron available are among those which, in contrast to "unit operations," we have chosen to call "total operations," Many of these problems, such as charging delays and the general mechanical problem of material handling, are so familiar that merely to define "total operations" brings them to mind. These problems are of such importance that already they have received careful thought and study and probably will merit further study. As will be shown later, these mechanical problems are so intimately related to metallurgical problems of total operations that the effect of certain changes cannot be ascribed with certainty to either a mechanical or a metallurgical cause entirely. Although the problems coming under the general term of "railroading" are included in the problems of total operations, two others are selected for the discussion of this paper. One of these is strictly a problem of composition; the other is strictly a problem of tonnage production. The problem of phosphorus is present whenever basic open-hearth slag is used in the blast-furnace burden. This practice has not secured universal acceptance chiefly because of difference in preference for high-manganese or low-manganese pig iron. If high-manganese (2.00 per cent) iron is to be made, open-hearth slag as a source of manganese is usually cheaper than man

Jan 1, 1943