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By Cyril Stanley Smith

METALLURGISTS - or at least metals - have been of central importance in most of the inventions that have shaped the course of man's history. From the first Bronze Age tools to the iron armor of the Roman soldier, the cannon, cast type for printing, the steam engine, the electric motor and modern electronic devices, technological progress has revolved around some particular property or comb nation of properties selected from the metallurgist's repertory. The recent utilization of the energy of the atomic nucleus (currently for military purposes alone but with great constructive implications for the future) is no exception to this, although the use of uranium and plutonium in metallic form is of secondary importance, since the significant properties are those of the nucleus and not of the electrons responsible for metallic behavior. THE METALLURGIST AND ATOMIC ENERGY The metallurgist has a role of central importance to play in the future development of atomic energy. Not only must he make and shape the fissionable materials themselves, but he must also develop auxiliary materials to withstand the extreme conditions imposed on nuclear reactor components by the high heat-transfer rates needed for efficient utilization of the fuel and by the perplexing but interesting effects of radiation on the structure and properties of materials. It is doubtful if there is currently any other field potentially more rewarding to a young metallurgist. Quite apart from the all important but relatively short-range considerations of national security is the vision of the effect on civiliza-

Jan 1, 1953

By F. V. Lenel, J. A. Dromsky

The influence of thermal and mechanical treatments upon the elevated-temperature stability, the microstructure, and the mechanical properties of aluminumaluminum oxide alloys is investigated. Compacts from atomized and flake aluminum powders were sintered at temperatures just below the melting point of aluminum in a vacuum of 10-4 Torr for several hours and were then hot-extruded. During this treatment the hydrated oxide present on the surface of the powder particles decomposes, the water vapor produced reacts with the aluminum forming additional oxide, and the hydrogen developed is removed by diffusion to the surface. Extrusions of compacts so treated are stable at temperatures up to the melting point of aluminum and do not form blisters and internal defects typical of extrusions from untreated powder. Electron micrographs of extrusions from unsintered compacts show long parallel oriented platelets typical of the IN previous investigations1,2 the properties and structure of aluminum alloys were described which had been produced by cold compacting aluminum powder and then hot pressing and extruding the compacts. Both the structure and the properties of these alloys differ significantly from those of commercially produced aluminum-aluminum oxide alloys. When commercial alloys are produced, they are given a sintering treatment in air at about 600°C between cold compacting and hot pressing.3 During this treatment the hydrated oxide, which forms the coating on the aluminum-powder particles from which the alloys are prepared, is decomposed.4 The chemically bound water which is released reacts with the aluminum and forms aluminum oxide and hydrogen. Most of the hydrogen is eliminated by hydrated oxide skins on the original powder particles, while the oxide particles in extrusions from sintered compacts are broken up. The strength of extrusions from treated powder is somewhat lower, but their ductility is considerably improved over that of extrusions from untreated powder. The slip-trace patterns on electron microgvaphs of extrusions which had been strained in tension before replication indicated that the grain size of the extruded alloys was approximately the same as that of the original powder particles. Coarse-grained alloys were produced by severe cold work and annealing of the extrusions. They have significantly lower room-temperature strength, but about the same ductility as the vacuum-sintered fine-grained alloys. The size and shape of oxides in the coarsegrained alloys is similar to those of the fine-grained alloys, but the particles are somewhat more uniformly distributed. diffusing to the interior or exterior surfaces of the compact, but it is difficult to eliminate all of it because the solubility of hydrogen in solid aluminum is very low even near its melting point. Extruded alloys which are not sintered before hot pressing and extrusion appear quite sound upon metallo-graphic examination, but develop severe surface blistering and internal fissuring when they are heated to elevated temperatures after extrusion. Fissures and blisters have been observed even in commercial alloys which had been sintered in air, although they are much less severe.' Because of the importance of this sintering treatment it was studied in this investigation in a modified form, using vacuum sintering rather than sintering in air, to insure more complete elimination of occluded hydrogen. The technique is described and the effect of the treatment upon the structure of the alloys is documented. It has been known for some time that extruded aluminum-aluminum oxide alloys are very finegrained, but an exact delineation of grains in electron micrographs has not been possible. In the conventional metallographic-etching techniques etchants attack the interface between the second-phase particles and the matrix in the alloys much

Jan 1, 1964

By Charles Catlett

Having had charge during the past year of the operations of the New River Coke Company, the second largest, if not the largest, coke-producer in this district, my attention was called particularly to the yield of coke from the coal as coked in a bank of beehive ovens, as the record showed that this yield, while believed to be well up with the practice of the district, was much lower than the analysis of the coal indicated it should be. The coal is well known to many members of the Institute, and the scope of this paper does not include a discussion of its occurrence and development. It suffices to say that the New River district comprises the mines working on the coals of No. XII. or the Conglomerate Series of the Rogers brothers, which are located on New river and its tributaries, and which find an outlet for their product east and west over the Chesapeake and Ohio Railway. The New river through this section carries the drainage from an extensive peneplain in which it has formed a very striking and stupendous canon, probably the most striking east of the Mississippi river. The only practical access to this territory is by means of this canon and the Chesapeake and Ohio road, and the opportunities for development by other lines may be considered as nil. If it were not for the fact that this road, farther west, reaches and develops entirely different coals, which are found in other measures, the New River district might properly be spoken of (as is now done at times) as the " C and 0. field." For fuller information on the geology of the region, those interested are referred to the ery complete monograph on the subject by Mendenhall and Campbell of the United States Geological Survey. The rocks are the same as those which carry the more widely

Jan 1, 1900

By B. S. Butler

STUDY of the ore deposits of Colorado has disclosed, in numerous places, sharp changes in both mineralogy and metal content of the primary or hypogene deposits with change in depth. A clear understanding of the meaning of these changes is requisite to form intelligent conclusions that can be applied in the exploration of such ore deposits. This paper is an attempt to set forth some of the geologic and chemical relations of minerals that bear on this problem. The effect of the differing electrode potentials of elements on the order of oxidation and on the order of displacement of one metal by another metal in supergene sulfide deposits has been studied for many years by several investigators. The results all agree rather closely with the original Schürmann series of replacability of metal sulfides, as Wells has shown.1 So far as the writers are aware there has been little attempt from the geologist's viewpoint to correlate the electrode potentials of the elements, other than those of the common metals, with the positions and mode of combination of the elements as found in ore deposits, and in particular in hypogene deposits. Wells2 discusses electrochemical activity between solutions and certain ore minerals and mentions the possibility of its effect in precipitation reactions.

Jan 1, 1929

By K. J. Miller, R. E. Hucko

The Coal Reparation Division of the Pittsburgh Mining Technology Center conducted an investigation to assess and compare the pyritic sulfur reduction potential of coal-pyrite flotation and high-gradient magnetic separation (HGMS). Tests were run on three coals - an Upper Freeport bed coal, a Lower Kittanning bed coal, and a Pittsburgh bed coal - to establish grade-recovery relationships characteristic of both processes. Representative portions of each coal sample were crushed to two top sizes-nominal - 500 pm (-35 mesh) and nominal - 149 pm (-100 mesh)-and subjected to conventional froth flotation. The froth product was then beneficiated by coal- pyrite flotation or HGMS, to provide a direct technical companion of the two processes. At - 500 pm (- 35 mesh), the size normally employed for coal flotation, both coal-pyrite flotation and HGMS effectively separated pyrite from coal, and the performance of the two processes was essentially the same. At a - 149 pm (- 100 mesh) sire, however, the performance of HGMS exceeded that of coal-pyrite flotation. The separation effected by HGMS were more efficient at - 149 pm (- 100 mesh) than at - 500 pm (- 35 mesh). On the other hand, it was concluded that either the effectiveness of coal-pyrite flotation decreases with diminishing top size or the process has not been optimized to treat material finer than 500 pm (35 mesh).

Jan 1, 1983

By W. H. Kantner

In this paper, no attempt will be made to theorize on subsidence. Only known data and actual facts will be given, with a few exceptions noted where other factors and outside influences tend to change subsidence directly resulting from porphyry caving. The area under observation is known as the Southeast Extension of the East orebody. The orebody is irregular in outline and dips to the south and the east, extending in depth from about 425 ft. below the surface to 1050 ft. below the surface. In the upper horizon, the orebody is about 400 ft. long and 150 ft. wide. At 720 ft. below the surface, the ore outline is approximately 450 by 170 ft.; 70 ft. below this, it is 500 by 110 ft., with an extension at the north end to the east 270 by 120 ft. From this elevation to about 900 ft. below the surface, the ore spreads out to the cast and south, being about 700 by 500 ft. between these vertical limits. Below this it pinches out and at 1060 ft. below the surface is only 100 by 100 ft. The nearest point of the orebody—which is on the northwest side—is 600 ft. 'southeast of the Sacramento shaft. The country rock is all porphyry. Fig. 1 is a vertical east-west section showing orebody and original surface. The surface over the orebody was fairly regular and in this area and adjacent to it were portions of the surface plant, roads, and the main plant railroad to the concentrator. Fig. 2 is a map of the surface over the porphyry area. Caving operations started in April, 1925, at the approximate top of the orebody. The first lift was on the 600-ft. level; the ore was extracted by means of the Morenci timbered slide method and was from 425 to 455 ft. below the surface over an area of about 22,000 sq. ft. This lift was finished in May, 1926. The second lift, on the 650-ft. level, was already in production by May, 1926, so extraction of ore was continuous. This lift was 48 ft. high and covered an area of about 30,000 sq. ft. The ore from this lift was extracted by means of a modified Morenci timbered slide method. This lift was finished in March, 1927. The direction

Jan 1, 1934

By T. A. Richard

We rejoice that the world-war is ended. We are proud of the part played by the English-speaking peoples—all doing equal honor to the traditions they share in common. One of the compensations for the calamity of the past four years is the fact that the Briton and the American, striving together in the cause of human liberty, have learned to understand and to respect each other. The mother country entered the fight resolutely at the beginning, while yet unready to meet the carefully prepared onslaught of the enemy; then the sons from the overseas dominions rallied to the old battle-cry eagerly and effectively; and last, but not least, the stepsons came from across the Atlantic, speaking the same speech, playing the same game, and fighting in the same clean way. It was a great foregathering of those that use the language of Shakespeare and idealize the principles of liberty for which the friends and associates of Shakespeare stood sponsor three centuries ago.' At a time like this it is pleasant to dwell upon the fact that the liberal Englishmen who organized the Virginia company were the pioneers of self-government on the American continent. The Virginia Assembly, convoked in 1619, was the first example of a domestic parliament to regulate internal affairs on this side of the Atlantic.2 The Governor of Virginia, Sir Edwin Sandys, had been a pupil of Richard Hooker at Oxford and from that political teacher he and his friends had imbibed the idea of combining civil liberty with constitutional order. To this group of large-minded Englishmen, the American colonists owed their liberal charters and their successive triumphs over the royal prerogative. Let it be noted that the American colonists had to deal with James II and George 111, the two smallest minds in the list of British kings. Another historical note, more pleasant to record, is the connection between the two principal groups of American settlers. In 1608, when the Pilgrim fathers, William Brewster and John Robinson, led their Separatist congregation to Holland and there prepared the expedition to America, they were assisted by Sandys and the Virginia Council, who were willing to share their privileges with them. When the Pilgrims set sail in 1620 they had the promise, obtained by Sandys from King James, that they should have freedom of worship,

Jan 1, 1920

By C. M. Nickerson

It is apparent that repressuring of the oil measures is becoming increasingly important to the oil industry, and is a matter that warrants the best efforts of the petroleum engineer charged with applying this method of operation to a producing property. Considerable attention has been directed to repressuring in various California oil fields, such as Dominguez and Seal Beach, which have served to sell the more progressive operator on this idea and also to keep him sold. The projects that have received most attention are in comparatively young fields where the fluid levels are high, the wells, perhaps, still flowing, where the wet gas production is of considerable volume, and where there is vital need of immediate conservation of gas, which otherwise would be blown to the air. The new State of California Gas Law, which prohibits the waste of gas, has served to interest the oil industry in means of conserving the gas that is now being blown to the air because of lack of markets. This vitally affects the operator in the older, well-depleted oil fields of the state, because in many cases he has a limited market for gas, on account of the flush production from the more active oil fields. While the waste of gas is relatively small in these older fields, such as the Midway-Sunset area, it now attains considerable importance, since under the new State Gas Law it must be put to some bcneficial use. Repressuring in the older fields of California has not received the attention of the petroleum engineers that is warranted by the present situation. This paper was prepared with the view of presenting the salient features connected with repressuring in the well-depleted oil measures of the older fields, and to show what results have already been obtained in these fields by injecting the unmarketable gas into the sands, particularly in the Midway-Sunset field in the San Joaquin Valley of California. Other projects in the older fields of the state offer some supporting data in this connection, such as the Shields Canyon and the Brea Canyon fields. Gas Storage and RepressuRing On account of the lack of market for a large portion of the dry gas produced in certain of the older, well-depleted oil fields of California, the

Jan 1, 1930

By Theodore H. Eyde

The porphyry-copper province of southwestern United States and northern Mexico constitutes the largest copper-producing region in the world. More than 20 deposits discovered since World War II are being exploited or in the process of exploration and development. Because of the remarkable success in discovering new deposits, exploration activity continues at a very high rate and deeper targets are explored each year. Exploration programs for deeply buried porphyry-copper deposits require a reevaluation of the conventional exploration techniques. Though surface induced-polarization techniques have about reached their practical detection limit, aeromagnetics will play an increasing role in the exploration activity as will downhole logging tools. In addition to a valid geological concept, any successful exploration program for porphyry-copper deposits in the southwest must have two other essential ingredients: money and guts. Unfortunately many exploration programs in the southwest are underfunded and doomed to failure. Future exploration will demand more joint venturing in which larger and more expensive exploration programs can be successfully funded by groups of companies or syndicates.

Jan 1, 1975

By Francis B. Foley

THE casting of steel in large molds brings into play all of the undesirable effects that result inevitably from slow cooling. The origin of the molten metal, whether basic or acid open hearth or electric furnace, has little if anything to do with the phenomena involved. If the quantity of molten metal to be cast in a single mold is large enough, there is very little one can do about it-the metal will cool so slowly that 'nothing one can do, other than to provide as good feeding as practicable from an adequate reservoir of metal in the sink head, will be of any avail. Recently we have had occasion to cast a 108-in. octagon ingot weighing 545,700 lb, necessitating the combining of metal from three 100-ton open-hearth heats. This is one of the largest ingots ever made. The body of the ingot weighed 448,800 lb, which includes a bottom pool of about 7500 lb of metal, and the sink-head weight was 96,900 lb, or about 18 pct of the total weight.

Jan 1, 1947

By R. J. Greaves

High-resolution seismic reflection profiling can be used to evaluate detailed structural and stratigraphic features of coal prospects. Since most coal prospects are relatively shallow, less than 1000 m (3000 ft) deep, high sampling rates in space and time can be used effectively to improve vertical and lateral resolution of seismic data. The case study presented here shows how seismic data was used to evaluate the Wyodak coal at a prospective coal gasification site. The data were used to map the detailed structure and thickness of the coal and to search for lateral discontinuities, such as pinchouts and faults. An important find was a paleochannel cutting across the base of the coal seam, which was later confirmed by drilling.

Jan 1, 1986

By B. A. Eaton, R. H. Jacoby

This paper presents the depletion-performance correlations developed using data from PVT studies and well-completion tests of 27 rich gas-condensate and volatile-oil reservoir fluids. The PVT behavior for each fluid war determined experimentally in the laboratory, and the depletion performance of each fluid was then calculated. Well-completion test data consisting of reservoir pressure and temperature, initial total gas-oil ratio, and stock-tank oil gravity were used with the depletion-performance data to develop general performance correlations. Three correlations are presented. The first equation shows the empirical relation of gas in place per barrel of hydrocarbon pore space with reservoir pressure and temperature, and initial total gas-oil ratio. The second equation is the correlation of stock-tank oil in place per barrel of hydrocarbon pore space. The third equation relates stock-tank oil production (to 500-psia depletion pressure) with pressure, temperature and oil gravity. All three correlations are also presented in convenient graphical form. Gas production to 500-psia depletion pressure is approximately 92.6 per cent of the gas in place for each fluid, so no correlation was developed for gas production. INTRODUCTION The rate of discovery of shallow, low-pressure and low-temperature oil reservoirs in the United States has been declining in recent years. For this reason, the search for oil has gone to greater depths where high pressures and temperatures are encountered. A high-pressure and high-temperature reservoir is the environment in which many rich gas condensates and highly volatile oils are found. Because of this trend, the performance prediction of such reservoirs has become an important task of the reservoir engineer. The need and usefulness of a performance correlation based on field data that are available from the usual well-completion tests have previously been established. These earlier attempts have shown that the phase behavior of rich gas-condensate systems and volatile-oil systems can be correlated with fluid properties, pressure and temperature. However, very little information on gas-condensate depletion performance5 was available at the time of these earlier attempts. The availability of more recent data has made possible the development of an improved correlation. The data, as listed in Tables I and 2, are for 25 gas-condensate and two volatile-oil systems that were studied. The problem was to correlate the data for in-place fluids and the production data with the initial total gas-oil ratio, initial reservoir pressure and temperature, and stock-tank oil gravity. These correlations were obtained by multiple regression analysis, whereby the data were fitted to an equation by the method of least squared error. BASIS OF THE CORRELATIONS 1. The data used in the development of these correlations were obtained from depletion-performance calculations6 and well-test or production measurements. 2. All of the independent variables used in the correlations are available from the usual well-test completion data. 3. The reservoir volume considered is 1 bbl of hydrocarbon pore space (HCPS). 4. The gas-oil ratio used is the total standard cubic feet of gas (at 14.7 psia, 60F) coming off the entire separator train per barrel of stock-tank oil. This minimizes the effect of separator conditions which might vary from system to system. 5. The correlated pressures are the actual reservoir pressures which might or might not be the saturation pressure of the reservoir fluid.

Jan 1, 1966

By K. N. Clark, N. B. Carter, C. G. Thomas, V 7. 0 / 300 dpi

A statistically designed, experimental study showed how gangue minerals, flux additions, fineness of grind, firing temperature, and time affect the properties of acid pellets made from a Western Australian hematite ore. Alumina has less effect than silica and lime, but interactions between the six variables occur, which influence abrasion index, reducibility, and cold compression strength. Finer grinding has little influence on reducibility but improves the other two properties. The major variable is firing temperature, which interacts with all other variables to affect pellet properties. Calculations based on the data show the implications for straight-grate pellet plants and optimum hood temperature ranges.

Jan 1, 1982

By R. F. Lee, G. Purcell

Tests carried out in the Department of Mining and Metallurgy at the New Mexico Institute of Mining and Technology indicate that high density rigid foams may, with the addition of suitable fillers, have structural properties comparable with concrete. Since polyurethanes have other useful properties that are unique to the foams, they have great potential value for both mining and civil engineering applications. Polyurethane, a generic term for a wide variety of closely related foam compounds, suggests rather misleadingly that foams are simple polymers of the urethane monomer ethyl carbamate (H,NCOOC,H,) . Polyurethane foams certainly do contain urethane groups, but these need not necessarily preponderate. Other reactive groups may be, and usually are, present so that the final polyurethane product will most likely contain, in addition to urethane groups, aliphatic and aromatic hydrocarbon, ester, ether, amide and urea groups.

Jan 9, 1963

By L. E. Paulson

INTRODUCTION The Northern Great Plains has 16 billion tons of strippable lignite (1). Presently, 15 million tons per year are mined; essentially all is used for generation of electrical power. In the future, additional large quantities will be consumed in the production of gaseous and liquid fuels. A major consideration in design and operability of power stations and conversion plants is the nature of the ash or inorganic constituents of the lignite used. These inorganic components cause fireside fouling in boilers, exert a catalytic effect in liquefaction and gasification, and contribute to particulate and SO2 emissions. Ash fouling on fireside boiler tubes cause reduced heat transfer and gas flow which limits boiler performance. Severe fouling can result in shutdown of the boiler. A comprehensive test program in both pilot plant and field studies at the Grand Forks Energy Technology Center (GFETC) has shown that ash fouling increases with increased sodium content of low-rank coals (2). The sodium in the coal can be

Jan 1, 1983

By Carl Lee

OXYGEN-FREE high-conductivity copper (OFHC brand) that is now being commercially offered for the first time represents a notable achievement in electro-metallurgy and is the outcome of endeavors that have extended over a long period. Its manufacture is novel in that electrolytically refined copper is melted in electric furnaces and cast into vertical water-cooled molds. The ingots show the "pipe" characteristic of sound gas-free metal and microscopic examination even at high magnification reveals no cuprous oxide in the copper. Owing to the patent situation, the United States Metals Refining Co., the producers, cannot at this time divulge the details of manufacture, but the operations are under precise control so that the castings are of great uniformity and the copper contains no residual deoxidant. Figs. 1 and 2 show photographs of cross-sections of a wirebar and a billet, both vertically cast.

Jan 1, 1933

By O. W. Simmons, L. W. Eastwood, C. M. Craighead

Eighty-four quaternary titanium-base alloys from the following systems were investigated: 1. Titanium-chromium-carbon-nitrogen. 2. Titanium-chromium-carbon with copper, vanadium, molybdenum, manganese, iron, or nickel. 3. Titanium-chromium-nitrogen with vanadium, molybdenum, or nickel. The tensile properties, minimum bend radii, hardnesses, response to heat treatment and aging treatment, and phase relationships of these alloys are reported. HIS paper is the third in a series describing J- titanium-base alloys. The first paper describingdescribed titanium binary alloys, and the second contained data on a large number of titanium ternary alloys. Eighty-four heats, comprising three groups of quaternary titanium-base alloys, are described in this paper as follows: 1. Titanium-chromium-carbon-nitrogen alloys. 2. Titanium-chromium-carbon alloys containing copper, vanadium, molybdenum, manganese, iron, or nickel. 3. Titanium-chromium-nitrogen alloys containing vanadium, molybdenum, or nickel. The methods of preparing, fabricating, and testing the alloys are described in the paper Binary Titanium Alloys. Quaternary Titanium - Chromiurn - Carbon -Nitrogen Alloys The properties of titanium-chromium-nitrogen and titanium-chromium-carbon ternary alloys have been described in the paper Ternary Alloys of Titanium. Because small amounts of nitrogen and carbon both appear to be somewhat beneficial, these additions have been investigated fairly completely in quaternary alloys containing chromium at the following levels of composition: 2.5, 3.5, and 5.0 pct chromium 0.25 and 0.5 pct carbon 0.1 and 0.2 pct nitrogen Mechanical Properties: The mechanical properties of these alloys are listed in table I. Fig. 1 and 2 show graphically a comparison of the tensile properties and hardnesses of quaternary alloys with those of the titanium-chromium binary alloys. Fig. 1 shows the comparison at 0.25 pct carbon, whereas fig. 2 shows the comparison at 0.5 pct carbon. It is concluded from these data that 0.25 pct carbon and 0.1 pct nitrogen are desirable additions to the 5 pct chromium-titanium base. It is further concluded that most of this improvement is produced by the nitrogen and that carbon is either harmless or mildly beneficial, at least up to 0.25 pct. Structure and Transformation Range: The effects of carbon and nitrogen on the transformation range of the titanium-chromium alloys were determined as part of the routine investigation. Additions of 0.25 pct carbon and 0.1 pct nitrogen had no appreciable effect upon the transformation range. However, the addition of 0.25 pct carbon and 0.2 pct nitrogen definitely raised the beta solvus temperature, as shown by fig. 3.

Jan 1, 1951

By J. C. Prof. Smock

(Read at the Philadelphia Meeting, February, 1878.) THE fire-clays of New Jersey belong in two geological ages, the cretaceous and quaternary, or post-tertiary. Three very small deposits of plastic clays have been discovered within the limits of the Archoean rocks. These are not refractory and of little importance, excepting in a geological consideration. They have resulted from a decomposition of the feldspars of the rock in situ, and they have been classified as inferior kaolins.

Jan 1, 1878

By Glenn S. Wyman

CHUQUICAMATA, located in northern Chile in the Province of Antofagasta, is on the western slope of the Andes at an elevation of 9500 ft. Because of its position on the eastern edge of the Atacama Desert, the climate is extremely arid with practically no precipitation, either rain or snow. All primary blasting in the open-pit mine at Chuquicamata is done by the churn drill, blasthole method. Since 1915, when the first tonnages of importance were removed from the open pit, there have been many changes in the blasting practice, but no clear-cut rules of method and procedure have been devised for application to the mine as a whole. One general fact stands out: both the ore and waste rock at Chuquicamata are difficult to break satisfactorily for the most efficient operation of power shovels. Numerous experiments have been made in an effort to improve the breakage and thereby increase the shovel efficiency. Holes of different diameter have been drilled, the length of toe and spacing of holes have been varied, and several types of explosives have been used. Early blasting was done by the tunnel method. The banks were high, generally 30 m, requiring the use of large charges of black powder, detonated by electric blasting caps. Large tonnages were broken at comparatively low cost, but the method left such a large proportion of oversize material for secondary blasting that satisfactory shovel operation was practically impossible. Railroad-type steam and electric shovels then in service proved unequal to the task of efficiently handling the large proportion of oversize material produced. The clean-up of high banks proved to be dangerous and expensive as large quantities of explosive were consumed in dressing these banks, and from time to time the shovels were damaged by rock slides. As early as 1923 the high benches were divided, and a standard height of 12 m was selected for the development of new benches. The recently acquired Bucyrus-Erie 550-B shovel, with its greater radius of operation compared to the Bucyrus-Erie 320-B formerly used for bench development, allowed the bench height to be increased to 16 m. Churn drill, blasthole shooting proved to be successful, and tunnel blasts were limited to certain locations where development existed or natural ground conditions made the method more attractive than the use of churn drill holes. Liquid oxygen explosive and black powder were used along with dynamite of various grades in blast-hole loading up to early 1937. Liquid oxygen and black powder were discontinued because they were more difficult to handle due to their sensitivity to fire or sparks in the extremely dry climate. At present ammonium nitrate dynamite is favored because of its superior handling qualities and its adaptability to the dry condition found in 90 pct of the mine. In wet holes, which are found only in the lowest bench of the pit and account for the remaining 10 pct of the ground to be broken, Nitramon in 8x24-in. cans, or ammonium nitrate dynamite packed in 8x24-in. paper cartridges, is being used. This latter explosive, which is protected by a special antiwetting agent that makes the cartridges resistant to water for about 24 hr, currently is considered the best available for the work and is preferred over Nitramon. Early churn drill hole shots detonated by electric blasting caps, one in each hole, gave trouble because of misfires caused by the improper balance of resistance in the electrical circuits. Primarily, it was of vital importance to effect an absolute balance of resistance in these circuits, the undertaking and completion of which invariably caused delays in the shooting schedule. Misfires resulting from the improper balance of electrical circuits, or from any other cause, were extremely hazardous, since holes had to be unloaded or fired by the insertion of another detonator. The advent of cordeau, later followed by primacord, corrected this particular difficulty and therefore reduced the possibility of missed holes. After much experimentation, the blasting practice evolved into single row, multihole shots, with the holes spaced 4.5 to 5 m center to center in a row 7.5 to 8 m back from the toe. Sucti shots were fired from either end by electric blasting caps attached to the main trunk lines of cordeau or primacord. The detonating speed of cordeau or primacord gave the practical effect of firing all holes instantaneously. Double row and multirow blasts, fired instantaneously with cordeau or primacord, proved to be unsatisfactory in the type of rock found at Chuquica-

Jan 1, 1953

By Glenn S. Wyman

CHUQUICAMATA, located in northern Chile in the Province of Antofagasta, is on the western slope of the Andes at an elevation of 9500 ft. Because of its position on the eastern edge of the Atacama Desert, the climate is extremely arid with practically no precipitation, either rain or snow. All primary blasting in the open-pit mine at Chuquicamata is done by the churn drill, blasthole method. Since 1915, when the first tonnages of importance were removed from the open pit, there have been many changes in the blasting practice, but no clear-cut rules of method and procedure have been devised for application to the mine as a whole. One general fact stands out: both the ore and waste rock at Chuquicamata are difficult to break satisfactorily for the most efficient operation of power shovels. Numerous experiments have been made in an effort to improve the breakage and thereby increase the shovel efficiency. Holes of different diameter have been drilled, the length of toe and spacing of holes have been varied, and several types of explosives have been used. Early blasting was done by the tunnel method. The banks were high, generally 30 m, requiring the use of large charges of black powder, detonated by electric blasting caps. Large tonnages were broken at comparatively low cost, but the method left such a large proportion of oversize material for secondary blasting that satisfactory shovel operation was practically impossible. Railroad-type steam and electric shovels then in service proved unequal to the task of efficiently handling the large proportion of oversize material produced. The clean-up of high banks proved to be dangerous and expensive as large quantities of explosive were consumed in dressing these banks, and from time to time the shovels were damaged by rock slides. As early as 1923 the high benches were divided, and a standard height of 12 m was selected for the development of new benches. The recently acquired Bucyrus-Erie 550-B shovel, with its greater radius of operation compared to the Bucyrus-Erie 320-B formerly used for bench development, allowed the bench height to be increased to 16 m. Churn drill, blasthole shooting proved to be successful, and tunnel blasts were limited to certain locations where development existed or natural ground conditions made the method more attractive than the use of churn drill holes. Liquid oxygen explosive and black powder were used along with dynamite of various grades in blast-hole loading up to early 1937. Liquid oxygen and black powder were discontinued because they were more difficult to handle due to their sensitivity to fire or sparks in the extremely dry climate. At present ammonium nitrate dynamite is favored because of its superior handling qualities and its adaptability to the dry condition found in 90 pct of the mine. In wet holes, which are found only in the lowest bench of the pit and account for the remaining 10 pct of the ground to be broken, Nitramon in 8x24-in. cans, or ammonium nitrate dynamite packed in 8x24-in. paper cartridges, is being used. This latter explosive, which is protected by a special antiwetting agent that makes the cartridges resistant to water for about 24 hr, currently is considered the best available for the work and is preferred over Nitramon. Early churn drill hole shots detonated by electric blasting caps, one in each hole, gave trouble because of misfires caused by the improper balance of resistance in the electrical circuits. Primarily, it was of vital importance to effect an absolute balance of resistance in these circuits, the undertaking and completion of which invariably caused delays in the shooting schedule. Misfires resulting from the improper balance of electrical circuits, or from any other cause, were extremely hazardous, since holes had to be unloaded or fired by the insertion of another detonator. The advent of cordeau, later followed by primacord, corrected this particular difficulty and therefore reduced the possibility of missed holes. After much experimentation, the blasting practice evolved into single row, multihole shots, with the holes spaced 4.5 to 5 m center to center in a row 7.5 to 8 m back from the toe. Sucti shots were fired from either end by electric blasting caps attached to the main trunk lines of cordeau or primacord. The detonating speed of cordeau or primacord gave the practical effect of firing all holes instantaneously. Double row and multirow blasts, fired instantaneously with cordeau or primacord, proved to be unsatisfactory in the type of rock found at Chuquica-

Jan 1, 1953