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By Dermot M. Ross-Brown

Introduction Slope angles are one of the major factors affecting the shape of the final pit and the location of the walls Due to differences in geology, the optimum slope angles vary from pit to pit and within different parts of the same pit. Indeed, it is not unusual to have different slope angles for the top and bottom portions of the same cross section. The optimization of these slope angles is a major study in itself and this chapter is intended as a general introduction to the subject. It is not intended to be a comprehensive text for the absolute beginner The objective is to put the various aspects of slope stability analysis into relative perspective by describing the vari¬ous analytical techniques available and indicating when each may be most appropriately used References are made to the many excellent texts and papers on slope stability for the reader who does not have a formal training in soil or rock mechanics. In writing this chapter, an assumption has been made that a tentative mining plan has been drawn up, includ¬ing a preliminary estimate of the slope angles. It has also been assumed that all the necessary field and laboratory data has been collected and reduced to a form suitable for input into the stability analyses.

Jan 1, 1979

By Benjamin LeRoy Miller, Joseph T. Singewald

For a number of years Russia, India and Brazil have outranked all other countries as producers of manganese ores. During the 5 years immediately preceding the European war, the average annual production of Russia was 844,000, of India 694,000 and of Brazil 200,000 long tons. Since the outbreak of the war there has been a considerable falling off in the Russian and Indian production, particularly in the former, whereas the production of Brazilian ores has been greatly increased, amounting in 1914 to over 250,000 tons and in 1915 to nearly 350,000, with conditions favorable for a still larger production in 1916. Manganese is one of the few industrially important metals that are not produced in the United States in quantity commensurate with our needs, so that we have been compelled to import annually about 300,000 tons, having a value of over $2,000,000, and these ores have been obtained from the three countries mentioned above. Their rank as contributors to our imports of manganese ores was India, Russia, Brazil; and in 1913, Brazil contributed only one-fifth. During the past 2 years Brazil has furnished rapidly increasing quantities to this country, and, with the falling off of imports from India and Russia, has become our principal foreign source. In 1914, Brazil furnished two-fifths of the imports and more than India or Russia, and in 1915 over nine-tenths. The manganese ores of Brazil are consequently of more than usual interest to us at this time. The Manganese-Ore Distbicts of Brazil , The manganese mining industry of Brazil dates from the year 1894, and since that year the total production has been over 3,000,000 tons. With the exception of a small quantity produced in the State of Bahia from deposits west of the City of Bahia, this output has come from the

Jan 1, 1917

By A. Hellawell

Binary alloys of compositions intermediate between solid-solubility limits and eutectic compositions have been completely separated into primary phases and eutectic by freezing unidirec-tionally at very slow rates (10-6 to 10-5 cm per sec). The alloys examined were Pb-1 wt pct Ag, Al-20 wt pct Cu, and Al-42 wt pct Cu. The compositions and proportions were close to those expected from the phase diagrams and provided information about the solid/liquid interface at certain free zing rates. DURING the directional freezing of an alloy the solute distribution is controlled by the efficiency of mixing in the liquid,'" whereas diffusion in the solid state is of negligible importance. It is known3 that mixing by convection is very efficient, but complete segregation is only achieved at very slow freezing rates4-6 or with forced stirring in the liquid. ' Yue9 and Yue and clark10 have previously illus- trated partial separation of primary phases in alloys close to eutectic compositions. In the present work, taking binary alloys of compositions intermediate between the limits of solid solubility and eutectic compositions, it has been possible to achieve complete separation of the primary phases by directional freezing at very slow rates. METHODS AND RESULTS The alloys concerned were Pb-1 wt pct Ag, A1-20 wt pct Cu, and A1-42 wt pct Cu. As may be seen from the relevant diagrams,11 these alloys should segregate into approximately equal proportions of primary solid solutions and alloy of eutectic compositions. Specimens, -12 cm long and 1 cm wide, were frozen in horizontal tubes by withdrawal from a furnace. The lead alloy, prepared from materials of 99.999 pct purity, was sealed into evacuated Pyrex tubes and the aluminum alloy of similar purity contained in graphite boats under vacuum. The molten alloys were seeded with some 3 cm of solid to prevent irregular initial freezing rates and the last portions to freeze were ignored. At the slow freezing

Jan 1, 1965

By Charles Legrand

The power plant of the Burro Mountain Copper Co. is located near Tyrone, N. M., at 5,950 ft. elevation. It is interesting because it uses the largest stationary Diesel engines in the United States. The general layout of the plant is shown in Figs. 1 and 2. The building is of steel-frame construction with hollow-tile walls and corrugated-iron roof; the floor is concrete and all windows have steel frames, making a fireproof building. The building is made to accommodate one more electric generator unit which is being installed; also two 4,000-cu. ft. air compressors direct-connected to three-cylinder engines with the same size cylinders as the electric units. The power plant consists of two 815-kva., 60-cycle, three-phase, 6,600-volt, 180-r.p.m. generators, direct-connected to five-cylinder, two-cycle Diesel engines; the necessary circulating pumps for cooling water, cooling towers and oil storage tanks. A portion of the power is used in the same building as the generating units to run one of two 200-kw. rotary converters delivering 260-volt direct current, and a 2,500-cu. ft. air compressor, delivering air at 95 lb. pressure, direct-connected to a 400-hp., 6,600-volt, three-phase synchronous motor. The remainder of the power is used to run a 1,500-ton concentrating mill 3 ½ miles from the power house, various hoists, pumps and motors about the mines and the lighting and water-works of the town of Tyrone. The direct current is used for electric traction in the mine, also to run hoists and motors that were installed before the new power plant was built. Due to the large hoists that take starting peaks of 250 kw. and the 10-ton electric locomotive that takes at times 150 kw., the load is extremely variable, as shown in. Fig. 3.

Jan 9, 1916

By Wayne Loel

THE application of aerial photographs to all phases of geologic mapping is set forth, indicating the advantages to be gained in different types of country and under varying climatic conditions, Methods of field and office procedure are given from a geological point of view, as well as suggestions regarding the best methods of aerial mapping for different uses and under varying field conditions, including the study of submarine geology. Aerial photographs with accompanying geologic maps are shown to illus-trate the appearance from the air of different geologic features under varying climatic and topographic conditions.

Jan 1, 1938

By W. R. Toeplitz

Probably a more descriptive title would be "Much Ado About Nothing." By "nothing," of course, I refer to the porosity which is the main feature of this type of bearing. Porosity has a decided effect on the manufacturing techniques, the structure and physical properties, the oil content, and on the installation and service of oil-retaining porous bronze bearings. A simple curve can be drawn by plotting specific gravity along the abscissa and percentage of porosity by volume on the ordinate. A bronze composition, analyzing 89 Per cent copper, 9.75 Per cent tin, and 1.25 per cent graphite, has an absolute solid specific gravity of 8.5. At this specific gravity, of course, occurs the point of zero porosity. Conversely, at loo per cent porosity, the specific gravity is zero. A similar curve can be drawn for bearings impregnated with oil; the only change being that the specific gravity at loo per cent oil will be 0.89 if we assume that that is the specific gravity of the lubricant. The curve is useful in determining the oil content by volume for any specific gravity. The normal range of oil content for porous bronze bearings of this composition is from 35 to 16 per cent, which is in the specific gravity range of from 5.8 to 7.3. In addition to the amount of porosity, the type of porosity is important. The first consideration here is that the porosity must be intercommunicating. This can be determined by a number of simple tests. The first method, which is very accurate, is to extract the oil in the bearing by cycling

Jan 1, 1945

By Harry M. Mikami

Chromite is the only ore mineral of metallic chromium and chromium compounds and chemicals. Because of this fact, chromite and chrome ore are used synonymously in trade literature. In commercial market quotations, chrome ore is the term commonly used. Chromite per se, because of properties imparted by its chromium content, is used in refractories and in special purpose moulding sands for metal casting. There are many other minerals containing some, generally minor, amounts of chromium, but none are commercial sources of the element (Thayer, 1956, p. 15). Chromium and chromite have many diverse uses that, directly and indirectly, critically affect vast segments of our modern industrial system. Most important are probably the metallurgical applications wherein chromium is a component of heat, abrasion, corrosion, and oxidation-resistant, and high strength alloys of many types. Stainless steels are the largest volume category of chrome-bearing alloys. Chromium chemicals are used in leather tanning, in pigments, dyes and mordants, printing, :hemica1 process industries, photography, pharmaceuticals, metal plating, pure chromium metal production, and for many other purposes. Chromite is a necessary constituent in basic refractories indispensable for the production of steel, copper, cement, and glass. Under present economic-political conditions, he U.S. and for that matter, North America, has virtually insignificant ore reserves of chromite. There are chromite deposits, as will be described, but they would only be used under highly abnormal conditions if all outside sources were cut off. All chromite used in the U.S. is imported from the eastern hemisphere in which are contained the principal world reserves. As the main suppliers in 1971-72 were the USSR, Turkey, Republic of South Africa, Philippines, and Rhodesia, the strategic nature of chromite is obvious.

Jan 1, 1975

By J. B. Morrow

WITH numerous plans under consideration for coal classification, and with the advent of the Bituminous Coal Code, the intelligent sam-pling of coal has become increasingly important. To us it is rather significant that there have been very few fundamental studies of coal sampling in American technical literature since those of E. G. Bailey, which appeared in the Journal of Industrial and Engineering Chemistry in March, 1909. He covered the subject up to that time so thoroughly and in such an excellent manner that perhaps many other later students have felt that they could add very little to his findings. The recent studies of the British Engineering Standards Association have indicated the possibility of a somewhat different interpretation of Bailey's results, permitting the taking of smaller samples, and perhaps it will now be helpful to reopen this question. C. W. H. Holmes, in an informative series of articles on coal sampling recently published in Colliery Engineering, makes two rather interesting statements, as follows: It is scarcely surprising to find a lack of interest and knowledge regarding the sampling of coal not only in the mining industry itself but also among consumers of industrial fuel: at its best coal sampling is a dirty business, regarded as a nuisance and an expense by the commercial man, and usually as a nuisance and nothing else by the chemist. The writer can conceive only two classes of people who have never experienced any difficulty in obtaining representative samples of coal from wagons; those who have never tried to, and those who have never had the necessity or desire to check the accuracy of their work. The primary purpose of this paper is to present some tabulated data of the more significant results of a sampling investigation undertaken during the last four years to obtain certain fundamental data on the variables connected with coal sampling and to point out that often assumptions have been made that are not in accordance with the facts. One of the standard sampling methods states:

Jan 1, 1935

By H. E. N. Stone, B. L. Daniell

This paper examines the cracking behavior on chemical reduction of three types of ore/oxide briquette mixtures. The complex sintering/hardening atmosphere was replaced by 100% oxygen and the blast furnace atmosphere by a 5/95 hydrogedsteam mixture which was used isothermally at 700°C for a constant, arbitrary time. Cracking has been assessed by measurement of reduction expansion or increase in specimen diameter as a result of chemical reduction and a subjective index based on appearance and friability. Oxidized briquettes of iron ore concentrate crack on reduction'-3 in a manner which parallels the degradation of sinter in the Linder test. In the present work, the cracking behavior on chemical reduction of three types of ore/oxide briquette mixture has been studied. Firstly, LD converter fume with additions of silica; secondly, Oxfordshire ore with ferric oxide; thirdly, ferric oxide with separate additions of silica, alumina and lime. Motivation for the first-mentioned experiments lay in the improvement of the fume as furnace feed; for the second, in assessing the tolerance of a finely divided ferric oxide as a base for low melting point additions. The third series provided additional information. In this work, the complex sintering/hardening atmosphere is replaced by 100% oxygen and the blast furnace atmosphere is replaced by a 5/95 hydrogen/ steam mixture used isothermally at 700°C for a constant arbitrary time. The particular reduction conditions were known from previous experience3 to be capable of disclosing any tendency to cracking. Cracking has been assessed by measurement of reduction expansion (i.e., increases in specimen diameter as a result of chemical reduction) and a subjective index based on appearance and friability. Generally

Jan 1, 1970

By G. C. Wallick

Since the appearance of the paper, "Solution of the Equations of Un-steady State Two-Phase Flow in Oil Reservoirs," by W. J. West, W. W. Garvin, and J. W. Sheldon,' a two-fold investigation of this subject has been carried out. One objective of the investigation has been to deter-mine the feasibility of solving such problems 7on a medium-size com-puter such as the Datatron*, and the other objective has been to in-vestigate the application of such cal-culations to experimental and theo-retical petroleum reservoir research. In the first Datatron calculations, the fluid and rock properties published by West, et al, were used, together with the published equations describ-ing the system. Details of the formu-lation not given in the original paper are discussed in the Appendix to this note. Reference should be made to the subject paper for the complete equations and defintion of symbols. An unexpected result of this in-vestigation was the discovery that the linear solution published by West was in error. Thus, in addition to describing the Datatron solutions and to discussing certain numerical diffi-culties which will be encountered if one uses the published method of solution, the purpose of this note is to indicate the nature of this error. LINEAR FLOW Since the linear case requires a minimum amount of scaling, a fixed-decimal point Datatron program was written for the one-dimensional flow problem and an attempt was made to duplicate the solution described by West. In the case described, fluid was produced at a constant rate, Q, until such time as well pressure reached 0.04. Production was then continued at constant pressure. From the constants and curves given by West it was determined that the ini-tial constant production rate could be approximated by Q = 0.007. An ini-tial dimensionless time step ?t = 0.434 X 10 - "as used, and each suc-cessive time step was doubled until a value of = 0.444 was reached. This constant interval was then used for the remainder of the solution. In subsequent solutions, several varia-tions in the time schedule were em-ployed, including smaller time steps and slower rates of increase in the time steps. In all cases, almost identical results were obtained regardless of the time schedule employed. However, as described below, it was noted that the time schedule had some influence on the rate of convergence of the solutions. As a check on the accuracy of the solution, the cumulative production at each time step was calculated using the two methods described in the Appendix. Satisfactory agreement was observed with the differences in these two values of the order of two parts in 50,000. It should be noted that the mass balance check as described is of questionable value, particularly with regard to the well pressure and saturation. This is especially true in the radial solution where pressure and saturation values near the wellbore would make only a negligible contribution to the numer-ical integration. It is believed, how-ever, that such a comparison is ot value in determining the over-all accuracy of a solution. In comparing the Datatron solu-tion with that published by West it was discovered that in the later stages of depletion, the pressures near the well declined more rapidly in our solution than in the West solution, and that the limiting well pressure of 0.04 was reached at an earlier time than that originally reported. It thus became evident that it would be impossible to duplicate the production schedule described by West and a constant rate of production was maintained until the well pressure was equal to 0.0. A representative comparison of the results published by West with those obtained in this investigation is shown in Fig. 1, which is a plot of GOR as a function of cumulative recovery. These two curves should be in agreement until a cumulative recovery is reached which corresponds to a well pressure of 0.04 — for the Datatron solution, a recovery of approximately 5.6 per cent. Actually, a major disagreement is evident. Subsequent correspondence

Jan 1, 1958

By F. G. Clapp

Introduction.......................................................... 915 Scope of Discussion................................................... 915 Literature and Acknowledgments....................................... 915 Geographic Distribution of Petroleum in South America................. 916 Geographical Comparison with North America.......................... 917 Geological Inferences Regarding South America......................... 918 Quality of South American Oil........................................ 918 South America's Position in the World's Production.................... 919 Political Conditions in South America................................. 920 Peru.................................................................. 920 Distribution of Peruvian Fields................................ :...... 920 Surface Indications.................................................. 923 Geological Conditions................................................ 925 Quality................................................,............ 927 Production......................................................... 929 Argentina............................................................. 932 Distribution of Argentina Fields...................................... 932 Surface Indications.................................................. 933 Geological Conditions............:................................... 935 Quality .......................................................... 936 Production.......................................................:938 Venezuela................................................. 939 Distribution of Venezuela Fields...................................... 939 Surface Indications................................................. 939 Geology of Venezuela Fields.......................................... 941 Quality........................................................... 942 Production.......................................................... 943 Colombia.............................................................. 944 Distribution of Colombia Fields....................................... 944 Surface Indications.................................................. 945 Geological Conditions............................................... 948 Quality............................................................ 950 Production......................................................... 950

Jan 1, 1918

By H. A. Guess

For a number of years I have used for the commercial wet assay of lead generally the ammonium molydate, and occa-sionally the ferrocyanide method. These well-known methods need no detailed description here. In the ore-selling and ore-buying establiahments of the West, 90 per cent. of all wet lead-assays are made by one or the other, and at least nine-tenths of this proportion by the molybdate method. A procedure so well-established must have merit; and, in

Jan 1, 1905

By H. S. Munroe

To those familiar with ore-dressing practice, it is hardly necessary to dwell upon the importance of the jig. Within its proper sphere no substitute has been found that does the work as well or as cheaply. Its capacity is large, it requires but little attention, and the losses are small. In one form or another, it is the principal machine used in the concentration of low-grade ores, and for the separation of one metallic mineral from another; and it is almost the only machine used for the purification of coal. The present paper is a study of the action of the jig in the light of results obtained in the Lake Superior copper mills, ad at the St. Joseph Lead Co.'s dressing-works, in Missouri; and a description of experiments undertaken with the view of reproducing and isolating the conditions of jigging, in order to develop the laws which underlie the process. There are two recognized systems of jigging, the English and the Continental or German. The English system is a development of the hand-jigging formerly employed in Cornwall and other metalliferous districts of England, and introduced by English miners to this country. In this method the crushed ore, coarse and fine together, is first jigged oh a

Jan 1, 1889

By E. S. Bumps, W. F. Craig, M. Baeyertz

Metallurgists have looked at fractures macroscopically for many years and have evolved a vocabulary in which such words as "cleavage," "brittle," "shear," "ductile," "granular," "fibrous," and "silky" are used to describe the appearance of the fractured surface; but the meaning of these words in terms of metal structure is not well established. Observations of the structural meaning of "brittle" and "ductile" fractures in plate steels have been made, notably, by Kramer and coworkers1 and by Tipper.2 Grossman3 has studied the fracture of tempered martensite and combinations of ferrite and martensite. Notwithstanding these and other less concerted attacks on the problem, present understanding of fracture rests more on assumptions and logic than on experiment. It is the purpose of this paper to add a little to the growing fund of experimental observations of the nature of fractures in steel. The particular fractures to be described were obtained in conventional impact testing of an ordinary structural steel shape. In impact tests of the Charpy type, the specimens fail in a characteristic manner that depends on the steel and the temperature of testing. With ordinary structural and many other steel products, an appropriate range of testing temperature will cause a considerable change in the energy absorbed before fracture. This change is known as the energy transition and is accompanied, more or less closely, by alteration in the appearance of the fracture. At testing temperatures below the transition, the terms "brittle," "cleavage," or "granular" are used to describe the fracture; above it, "ductile" or "shear" are often used. Within the transition, the fracture changes from "brittle" to "ductile" by a progression in appearance, wherein the "brittle" portion of the fracture becomes restricted to a smaller and smaller central area of the fracture, as the testing temperature is raised and the "ductile" type of fracture is approached. All this is well known to metallurgists. The specimens under consideration are of the conventional V-notch Charpy type. They were taken from a structural steel shape of the following analysis: C Mn P S Si 0.17 0.46 0.009 0.029 0.03 Both longitudinal and transverse specimens were tested and examined. Fig 1 shows the energy values plotted against testing temperatures in the usual way. The curves for both longitudinal and transverse specimens show an energy transition, although the maximum energy absorbed at testing temperatures above the transition is greater in the case of the longitudinal specimens. Fig 2 illustrates the changes in the macroscopic appearance of the fractures that are associated with the energy transitions shown in Fig 1. Macrographs of the fractured surfaces of the specimens have been identified with the fracture ratings at intervals on each fracture curve. The numerical fracture rating on the ordinate of Fig 2 indicates the percentage of the area of each fracture that was considered to be "brittle" on macroscopic observation. Such rating of the fracture type in impact tests is now customary in many laboratories. Hereafter the specimens will be identified by reference to Fig 2 as 90 pct "brittle," 80 pct "brittle," and so on, in accordance with this macroscopic evaluation of the appearance of the fractured surface. The discussion of the fractures is divided into three parts. The first two are concerned with the mode of fracture and its relation to general structural features. As the same metal-lographic features occur in both longi-

Jan 1, 1950

By O. D. A. Pease, C. D. Young, C. H. Strand

In an effort to employ cast steel of a stronger structure than that found in the annealed steel casting, the possibilities of heat treatment which will increase the strength without materially decreasing the ductulity may be resorted to.

Jan 1, 1915

By R. B. Burt, James A. Barr, I. S. Tillotson

THE pumping of solids in water suspension is an important part of many metallurgical and mining operations. In most cases, it is still in the rule of thumb category for which no universal formula has been developed, and much research is needed. Because of the limited and incomplete data available, this article may be classed as an experience paper, which is presented with the hope that some contribution will be made toward the development of the so-called universal formula. This formula, if and when developed, may be evolved from several factors, many of which are not now available for general application. The designing engineer is interested in obtaining accurate forecasts on: 1-the minimum velocities needed to prevent choke-ups in the pipeline, which in turn dictates pipe sizes, 2-power required for pumping, 3-pump selection. The basic factors for a given problem will include: 1-weight per unit of time of solids to be handled, 2-specific gravity of solids, for calculation of volume, friction and power, 3-screen analysis of solids with the colloidal acting, i.e., the slime fraction, a very important factor, 4-shape of particle or some means of determining a friction constant, 5-effects of percentage of solids, 6-development of a viscosity factor to be used in the overall calculations, 7-calculation of the lower limits of pipeline velocities permissible, 8-calculation of total head, pump horsepower, and 9-setting up of pump specifications. In certain limited cases horsepower and total heads and minimum velocities may be computed and a suitable pump selected from basic data, but in many cases, as in mining of Florida pebble, phosphate, experience rather than a hydraulic formula still should be used as a basis of selection. Pumping Florida Pebble Matrix Pumping at the Noralyn mine of International Minerals and Chemical Corp. will be used as an example. Other areas will vary as to the characteristics of the matrix, especially the slime content. A typical screen analysis of this matrix is: +14 mesh, pebble size,* 2.1 pct; -14 +35 mesh, 11.4 pct; -35 +150 mesh, 60.5 pct; -150 mesh, 25.0; total, 100 pct; moisture in bank, 20.0 pct; weight per cu ft in bank, 120 lb. The -150 mesh fraction may increase to as much as 35 pct in adjacent areas. When thoroughly elutriated, the matrix has a relatively slow settling rate, which is an important factor in permitting lower pipeline velocities without choke-ups. Exact data is not available to evaluate settling rates. For a factor of 100 a suspension of clean building sand in water is suggested. When pumping long distances, a quick settling matrix allows the coarser solids to settle out along the bottom of the pipeline, causing drag, turbulence, and increased friction. With a slow settling matrix as at Noralyn, turbulence acts to keep the solids in suspension at a lower friction head, regardless of the pumping distance. When the pebble, content of the matrix, i.e., the +14 mesh fraction, is in excess of 10 pct of the total solids, trouble may be expected from settling out even in normal pumping distances. To prevent choke-ups and maintain tonnage, an additional pump must be added in the long runs, where one pump would otherwise be satisfactory. A typical pulp handled is: total volume, 7800 gpm; water, 4500; solids pumped per hr, 4200 lb; sp gr pulp, 1.4; percent solids in pulp, 46.; pipe size, 16-in. ID; pulp velocity, 12.85 fps; probable critical velocity, 10 fps, as below this minimum -velocity choke-ups would be numerous. In calculating friction heads the Armco handbook is used where a roughness factor based on 15-year-old pipe is set up. Because the pipe used in pumping matrix is, smooth and- polished because of the scouring, action of the phosphate and its silica content, the head losses in the Armco table for water are practically the same as in pumping the Noralyn matrix through smooth pipe, plus the fact that conditions vary widely over short periods, making accurate determinations difficult to obtain. New pumps and pump, changes are being tested continuously and a wealth of data built up. This has resulted in a substantial improvement and lower relative costs in pumping matrix. The Florida phosphate industry is constantly seeking to offset higher wage and material costs with improved technique. Until a few years ago a 12-in. discharge pump was commonly used, with heads as low as 80 ft. Sizes have gradually increased and heads more than doubled. For example, the following pump was placed under test at the Noralyn mine: make, Georgia Iron Works; size, suction 16 in., discharge 14 in.; impeller, 39-in. diam; motor, 600 hp, slip ring; full load speed, 514 rpm. The results were increased head, higher capacity than the older design, with fewer pumps in the line from mine to washer.

Jan 1, 1952

By W. R. Hansen, F. W. Boulger

Twenty-nine laboratory steels were studied to determine the effects of composition and ferrite grain size on drop-weight and Charpy V-notch transition temperatures. The experimental steels covered the following ranges in composition.. 0.10 to 0.32 pct C, 0.30 to 1.31 pct Mn, 0.02 to 0.43 pct Si, md nil to 0.136 pct acid-soluble Al. Although most of the data were obtained on hot-rolled samples, some plates were heat-treated in order to cover a wider range in ferrite grain size. The experimental data were used for a multiple-correlation analysis conducted with the aid of an electronic computer. The study showed that carbon raises and that manganese, silicon, aluminum, and finer ferrite grains lower both drop-weight and Charpy transition temperatures. Quantitatively, variations in composition and grain size have a more marked effect on V15 Charpy transition temperatures than on the drop-weight transition temperature. Useful correlations were found between transition temperatures in drop-weight tests and those defined by seven different criteria for Charpy tests. Evidence was accumulated that the conditions ordinarily used for drop-weight tests are more severe for 1-1/4-in. -thick plate than for 5/8- to 1-in. -thickplate. PROJECT SR-151, to study quantitatively the effects of metallurgical variables on performance in the drop-weight test, was established by the Ship Structure Committee late in 1958 on recommendation of the National Academy of Sciences, National Research Council. This project was initiated as a result of the increasing use of the drop-weight (nil-ductility) test in predicting the ductile-to-brittle behavior of steel. Qualitative data indicated the drop-weight was not as sensitive to metallurgical variables as the Charpy V-notch test. Furthermore, the available information indicated that the drop-weight test did not show the superiority of killed steels over semikilled steels reflected by Charpy tests. This difference in sensitivity to brittle fracture is considered important because the drop-weight transition temperature has been reported1 to correlate better with service-temperature failures than the V-notch test does at a constant energy level. Therefore, this project was concerned with establishing quantitatively the effects of metallurgical variables in the drop-weight test. For comparison, Charpy V-notch data were obtained for the steels investigated. This paper summarizes the results of the investigation. Most of the steels used for the study were made and processed in the laboratory. However, some tests were also made on commercial killed steels available from Project SR-139 (SSC-141). During the course of the investigation, data were obtained on the effects of carbon, silicon, manganese, and aluminum on transition temperatures of drop-weight and Charpy specimens. In addition, the effects of heat treatment which changed the ferrite grain size and the transition temperatures were also investigated. Finally a few exploratory studies were made on commercial killed steels to evaluate the effects of plate thickness, grain size, and heat treatment on the performance of drop-weight specimens. EXPERIMENTAL PROCEDURES Preparation of Materials. A total of twenty-nine 500-lb induction-furnace heats were made and processed in the laboratory for the investigation. Carbon, manganese, silicon, and aluminum contents were systematically varied. Melting and rolling techniques proven satisfactory in a previous project2 were used as a guide for the current investigation. Composition. The composition of the twenty-nine laboratory heats made for this project are given in Table I. The steels are divided into three groups. The first group consists of ten aluminum-killed steels similar in composition to Class C ship-plate steel. The second group consists of ten semikilled or Class B type steels. In both of these groups the carbon and manganese contents were intentionally varied over a wide range. This wide range in composition was helpful in obtaining quantitative data from a limited number of steels. The primary purposes of these two groups of steels was to determine the effects of carbon, manganese, and deoxidation practice. In addition, one steel in each group (Steels 2-2 and 9-2) were made about 1 year after the start of the program in order to check consistency of melting practice. The third group of nine steels listed in Table I was intended for studies on the effects of silicon and aluminum. In eight of these steels carbon and manganese were held relatively constant at levels of about 0.2 and 0.8 pct, respectively, while silicon and

Jan 1, 1963

By George Bain

SOME problems concomitant with commercial exploitation of marble are presented as examples of interesting, useful and profitable fields for application of scientific knowledge. The marble industry is only one such field and is selected because its varying new aspects are familiar to the author. However, what is true for marble is equally so in principle for many industrial minerals. The problems of any stone industry are to maintain markets, create new outlets for stone already in demand, and develop varied uses for varieties that are not so popular. Here the geologist has a different role from most of his colleagues in metal mining. The producing branch may ask about the expectable variation in thickness or size of a deposit as development proceeds. The stock department may call for the available amount of a given type of stone before accepting a large order. The sales force requires data on the use for stone from certain parts of deposits in order to divert grades to the most suitable use. The service depart-ment wants defects rectified and the cause determined to avoid recurrence. The mills want data on durability and cutting quality of abrasives. The geologist occupies no special department; he is on general call, as may be illustrated by a few types of problems that may be classified as: (1) dominantly geological in character, (2) dominantly chemical in character, (3) dominantly physical in character.

Jan 1, 1940

For the first time in its history the Institute will hold a meeting in the State of Arizona. A few years ago Arizona stood third in the copper-producing districts of the United States. Since that time, with the development of porphyry mines, the output has gone up with great rapidity until it not only is the leading district, but its output at the present time is at the rate of nearly double the Montana output, which now stands second in the list. In connection with this .development, most interesting departures have been made in methods -of mining, concentration and smelting. Principles of mining and metallurgy of the greatest interest will be covered by papers which will' appear in the Bulletin and be presented at Technical Sessions, while ample opportunity will be afforded for those who go to the meeting to see all the points of interest .to them. In addition, members will be well rewarded by the marvelous natural features to be seen on the trip, including 'the petrified forests, the cliff dwellings on the Apache Trail and the Grand Canyon of Arizona. It is planned to start the special train from New York, but members and guests may join the special at other points en route as indicated by the following schedule: ITINERARY . , Thursday, September 14th Lv New York, Grand Central Terminal.. ............... 5.30 p. m. Dinner in dining car a la carte New England Members via B. & A. R. R. . Lv Boston. ............. (Regular train). ............. 2.00 p. m. Lv Worcester. ........... (Regular train). ............. 3.12 p. m. , Lv Springfield. ........... (Regular train). ............. 4.37 p. m. Dinner in Dining Car a la carte Ar Albany.. ......... .New York Central R. R.. ....... 7.45 p. m. Lv Albany .......................................... 9.00p.m. Lv Schenectady.. .................................... 9.32 p. m. Lv Utica ............................................ 11.08~.

Jan 8, 1916

By N. Schapiro, R. J. Gray, G. D. Coe

A petrographic and chemical investigation was conducted to determine the occurrence and distribution of the organic and inorganic forms of sulfur in various size and specific gravity fractions of a high volatile, A-rank, Pittsburgh seam coal. The investigation was conducted to aid in the resolution of the problem of how metallurgical coke of lower sulfur content can be produced from high sulfur coals. The Pittsburgh raw coal contains about 2.4% S in two dominant forms: pyritic and organic. Pyritic sulfur constitutes about 57% of the total sulfur in the raw coal and occurs in macroscopic and microscopic-size particles. A plant cleaning process mechanically separates between 50 and 60% of the pyritic sulfur, mainly the macroscopic particles. The organic sulfur constitutes 41% of the total sulfur in the raw coal and 55% of the sulfur in the washed coal. Thus, organic sulfur is not reduced by physical methods of separation. Organic sulfur occurs in all the coal entities, but in general, increases as the exinoid content of the coal increases. In this study, it was found that carbonizing certain selected low gravity coal fractions containing an average of 0.45% pyritic sulfur and 1.01% organic sulfur produced cokes containing an average of 0.22% pyritic sulfur and 0.91% organic sulfur. However, the organic sulfur in the coke is probably derived in part from the heating of pyrite in the presence of carbon. Thus, the total sulfur in the coal carbonized is the most important factor affecting the sulfur content of the coke produced. Concentration of microscopic pyritic and organic sulfur in the middling-type coal indicates the necessity for rejecting as much of this material as is economically feasible. Most of the sulfur introduced into the blast furnace originates from the coke. Although the sulfur content of the hot metal can be controlled by the addition of flux, the flux used restricts the productivity of the furnace by displacing ore and requires first to be smelted; therefore, low sulfur coke is highly desirable. Since the sulfur content of coke is dependent upon the sulfur content of the coals from which the coke is produced, low sulfur coals are required to produce low sulfur coke. In the western Pennsylvania area, large quantities of good coking coal are available from the Pittsburgh seam, but this coal unfortunately contains relatively large quantities of sulfur. To provide information that might be useful in reducing the sulfur content of this coal in the cleaning process, an investigation was conducted to determine the physical and chemical forms in which this sulfur occurs and with what petrographic components it might be associated. The Pittsburgh seam coal, like most other coals, contains two dominant forms of sulfur: one occurs as the minerals pyrite and/or marcasite and is referred to as pyritic sulfur; the other is combined with the coal substance and is called organic sulfur. Pyritic sulfur is amenable to physical methods of separation, whereas organic sulfur is not. Pyritic sulfur particles must be freed from the surrounding coal if they are to be removed in the washing process. Generally, this requires crushing; the required degree of crushing being a function of the size and distribution of the pyrite. The present investigation was conducted to 1) determine the size, distribution and association of sulfur-bearing minerals in the coal and 2) to determine whether the organic sulfur has a preferential association with specific coal entities. If a preferential association exists, this knowledge may be useful in devising a method for organic sulfur reduction. In addition, a study was made to determine the extent to which pyritic and organic forms of sulfur in the coal contribute to the sulfur in the coke produced from this coal. A representative 3%-ton sample of raw coal was crushed to —3 in. and screened into square-mesh sizes: 3 to 1 in., 1 to % in., % to % in., % in. to 10 mesh, 10 to 35 mesh, and 35 to 200 mesh. Separate samples of the -200-mesh fraction and the all-size composite were also collected. Each size fraction (except the -200 mesh) was fractionated on heavy liquids of the following specific gravities: 1.280, 1.300, 1.325, 1.350, 1.375, 1.400, 1.425, 1.450,

Jan 1, 1963