Search Documents

By Thomas J. Ferree

The principle mineral concentration practices today can be divided into three basic process categories: magnetic separation, flotation and gravity separation. The basic processes have been in use for many years with only limited changes occurring in equipment design or process technique. In general, equipment and process techniques have been altered only after a need for change has developed. With exceptions for changes necessitated by new environmental laws, most equipment and process improvements have evolved in accordance with the desire to concentrate larger quantities of material at lower costs. The basic result has been the development of larger capacity equipment, to wit: larger flotation cells, larger blast furnaces, larger haulage equipment and larger chemical process equipment. However, there has been practically no changes in the size of spirals, tables, jigs, or-within limits- magnetic separators. (The exception being high-intensity magnetic separators). Consequently, a "new" device has entered the scene which may fill a void in the gravity separation field. It is called a Reichert cone concentrator.

Jan 3, 1973

By D. Harrington

ALTHOUGH statistical data are not at hand to justify definite statements as to progress in health, and safety in the mining and allied industries during 1935, it now appears probable that in both coal mining and in metal- mining the rate of accident occurrence as well as the absolute number of accidents will show slight increases for the year. Much: of the responsibility for this increase lies with the large number of relatively. small mines that have more or less recently come into existence, partly because of 'the lack of opportunity for work in the larger mines for large numbers of unemployed miners, and partly due to increased prices for some of the mineral products, especially gold. In general, the larger long-established nines show downward accident trends and this is decidedly encouraging as it shows that where mines are operated with real efficiency, mining can be done in relative safety.

Jan 1, 1936

By Julian Kennedy

THINKING that it may prove of interest to the Institute, 1 have prepared a short; account of the blowing in and subsequent working of the "A" furnace of the Edgar Thomson Steel Works. This furnace was built for the purpose of making spiegel, but has been started and is now running on Bessemer iron. The shape and size of the furnace are shown in the accompanying drawing. It will be seen that the section is formed of lines making very small angles with each other. In fact, an arc of a circle can be drawn, from the top to the tuyeres, which will nowhere deviate more than two inches from the lines given. In building, also, great pains were taken to gradually round the angles, so that the most careful observer, standing in the crucible and looking upward, could not tell at what points the slopes changed. It will also be seen that the widest part of the furnace is almost exactly midway between the bottom and the stock line. The flattest slope is maintained for 20 feet above the crucible, and is about 18 inch to the foot from the perpendicular. The furnace is lined with small brick throughout, and has six tuyeres four inches in diameter, which project seven inches inside of crucible. There are three Siemens-Cowper-Cochrane stoves, each 15 feet in diameter by 50 feet high. Blast is furnished by an upright engine with 32-inch steam cylinder, 84-inch air cylinder, and 48-inch stroke. The steam cylinder has balanced poppet valves, working horizontally. The steam valves are worked by a Porter link-movement in order to obtain a variable cut-off. The exhaust valves are worked by a separate eccentric. It is intended to attach a governor to the cut-off, but at present it is set by hand. The steam cylinder is

Jan 1, 1880

By L. C. Snider

NO important discoveries of petroleum during 1932 are reported from Canada. New Brunswick, which has a small production from one field, was inactive, and the production showed a decline from 6600 bbl. in 1931 to about 6300 bbl. for the year 1932. The old fields in Ontario increased from 123,000 to about 131,000 bbl. Alberta showed a decline of more than one-third, from 1,413,631 bbl. in 1931 to about 913,000 bbl. in 1932. This decline was due principally to the restrictions placed on the flow of gas wells in the Turner Valley field, from which the crude naphtha is obtained that accounted for more than 93 per cent of the production of Alberta and for more than 80 per cent of the production of all Canada in 1932. The starting of new wells to the limestone that produces the naphtha-bearing gas was prohibited late in 1931, and only wells started before that time were finished during 1932. One well was drilled in the Turner Valley field to a depth of 7555 ft., establishing a depth record for Canada. It passed out of the Madison limestone at 5560 ft., and encountered showings of oil in the underlying formations, probably of Devonian age. Commercial production had not been established by the end of the year. Commercial oil wells were brought in in two areas in Ontario which had previously been considered as productive of gas only— in the Dawn gas field, Lambton County, and in Raleigh Township, Kent County. The discovery wells had initial productions of about 50 bbl. per day, but no production of major importance is indicated. In Alberta, outside the Turner Valley district, two wildcats were drilled northwest. of Lethbridge in the Keho Lake vicinity. Both failed to make commercial producers in the Madison limestone, but one was testing upper sands at the close of the year. Good showings of oil are reported. A very small production was found in the Madison limestone in a wildcat well on the Twin River structure southeast of Lethbridge and another well has been started near by on what is considered on geophysical evidence to be a better location structurally. About 15 locations were made on the Canadian side of the border north of the Cut Bank development in Montana.

Jan 1, 1933

By Theron Wasson

Michigan produced 16,637,000 bbl. in 1937. This makes it a record year in the history of Michigan's oil industry. During the year 953 wells were completed; 779 within the limits of established fields and 174 wildcats; 616 new oil wells, 68 gas wells and 269 dry holes. Table 1 has been arranged in alphabetical order of field names. Production figures for 1936 have been corrected because December figures were estimated. In this year's summary, December production is based on actual reports. The Leaton and Mt. Pleasant fields have been re-defined. Mt. Pleasant production north of the south line of Denver township, Isabella County, has been included with Leaton in accordance with usual practice in Michigan. The locations of fields discovered since the last map was published1 are shown in Fig. 1. Activity during 1937 Buckeye Field.—The Buckeye field of Gladwin County was the center of greatest activity during the year and was responsible for the increase of 4,700,000 bbl. over the state total for 1936. Buckeye produced 6,428,-000 bbl. in 1937. In this field 328 producing wells were completed during the year—over one-half the oil producers drilled in the state. Buckeye was subject to voluntary and cooperative proration from April 1 to the end of the year. Other pools of the state were not prorated. The new production at Buckeye is from porous Dundee limestone of Devonian age, similar to the older fields. Other New Fields.—The Sherman field was second in importance as a source of new production, with a total of 1,532,000 bbl. Salem township, Allegan County, on the southwest side of the Michigan Basin, was developed during the year. Production at Salem is from the Traverse limestone at a depth of 1600 ft., and 52 producing wells have been drilled in this pool. Other active pools were Clayton and Adams townships, Arenac County. The Bentley pool, discovered in October 1937 southeast of

Jan 1, 1938

By A. C. Veatch

THE MIDLANDS of England contain large areas of important oil lands, which, however, will not become of commercial importance for at least 5 years, because the ownership of the oil has become a political issue. In Great Britain, except in certain special areas, all minerals, except for gold and silver, belong to the surface owner. The leasing of minerals on the large estates is a very complicated business, as the family solicitors have many forms and formalities that must be observed. In the case of one of the large estates, the principal revenues of which for several hundred years have been from coal leases, the average time between the agreement on terms for a coal lease and the signing of the same has been 8 years. In 1916, one coal lease on this estate had been pending for 15 years, and was still unsigned, although the important terms had been agreed upon 15 years previously. Under war conditions, and considering the extreme importance that the production of petroleum in England would have had, such delays could not be tolerated. Most of the British landlords, relying on the almost, universal opinion of their own countrymen that there were no commercial deposits of petroleum in Great Britain, were prepared to give all their oil rights to the government, but they feared that such action might establish a precedent with respect to coal. For years the Labor Party and extreme radicals have protested against the payment of royalties to landlords on coal. The government, therefore, introduced a bill taking over all the oil rights and providing for the payment of a small royalty to the landlords, to safeguard the principle of compensation in case the coal mines should ever be nationalized. The provision of this bill, with respect to the payment of royalty to landlords, was defeated by a vote of 44 to 35 in a night session of the House of Commons on Oct. 25, 1917, when most of the members were absent, but when a group of labor members and extreme radicals were present. The resubmission of the point to the House of Commons was prevented by the labor members of the coalition government, who reminded the cabinet that the agreement

Jan 1, 1920

By T. Wasson

Midland and Isabella counties have been the centers of activities for the year 1932. The major part of the 6,967,000 bbl. produced during the year was obtained from the old Mt. Pleasant field and the Eastern Extension field. The total production to the end of 1932 for Michigan, from all fields since discovery, is 20,679,600 bbl. Production in the Eastern Extension field was obtained from Dundee limestone of Devonian age, at a depth of about 3600 ft. As a result of the year's activity in this area, the limits of the Eastern Extension have been defined. No new fields have been discovered. A number of prospective areas have been drilled and condemned by dry holes. Probably the most outstanding development of the year was the discovery of oil on the Yost farm, in sec. 35 of Greendale Township, Midland County, by the Pure Oil Co., in the early part of December. Production is from the Dundee limestone similar to that in the Eastern Extension but is 4 miles south of that area. The first well has averaged about 500 bbl. per day since completion. It is near the center of a solid block held by the Pure Oil Co., so that rapid development due to competitive drilling is not expected. During the early part of the year the Midland-Isabella area was under proration, but on May 17 proration restrictions were discontinued and remained so until the end of the year. While the Eastern Extension saw the principal activity, some work was done in other fields of Midland and Isabella counties, but very little new production was added. The Vernon field on the north showed a slight increase in production over 1931. The Leaton field decreased. The well in Porter Township, Midland County, is still kept in the production ranks but very little drilling was done in that area. The old Saginaw field, Saginaw County, still remains the only spot in the state where commercial production is obtained from the Berea sand. It showed a slight decline over 1931 with no new producers for the year. The Muskegon field on the west side of the state showed a considerable decline over 1931, but owing to the rejuvenation of some wells by the use of acid this drop was not as great as might have been expected. Only two new producers were drilled in that area.

Jan 1, 1933

By Arthur Phillips

THE study of anisotropy in metals has been greatly stimulated in recent years by the rapid development of X-ray methods for determining the crystallographic relationships of wrought and annealed materials. Prior to this time the knowledge regarding the directional properties of commercial alloys consisted almost exclusively of observations of a practical nature made during the fabrication of metal objects, supplemented by a limited number of mechanical tests on specimens cut at various angles to the direction of working. Such observations clearly indicate that the common methods of cold-working metals cause both a crystallographic and a mechanical fibering varying in character and degree according to the nature and extent of the deforming process. Even after annealing, following certain not too well known combinations of reductions and anneals, a preferred orientation may exist, thereby constituting a residual fiber effect sufficiently pronounced to manifest directional properties. With the application of the X-ray the experimental horizon was extended chiefly because the study of anisotropic metals promised to offer direct and quantitative evidence regarding the involved mechanism of fragmentation and plastic flow. As a natural consequence the intensive studies in this direction have yielded a vast accumulation of data of ultimate potential value. Unfortunately, however, as is commonly the case in entering a virgin field of experimentation, many of the data cannot be molded into complete and coherent form because of the many unrelated conditions of the experimental projects. Again, the results of the study of single crystals have been rather naturally but at times indiscriminately applied to polycrystalline metals. Furthermore, sweeping statements have been made regarding the behavior during working and annealing of metals and alloys, entirely on the basis of similarity in lattice arrangement. There is abundant reason for believing that relatively small concentration variables, differences, in magnitude and distribution of applied stresses, and the character of associated annealing treatments may in some cases greatly influence the mechanics of flow and consequently largely determine the final structural characteristics of the metal.

Jan 1, 1932

By Fred McConnell

FROM beginning to end, the processes of coal stripping are of great interest. From the time the prospector enters upon the property to examine it and to prove it, until the coal is loaded into railroad cars, every step must be taken with careful thought and planning. In proving the merits of a prospective property, an examination and computation of the overburden is of almost equal importance to the determination of the extent and quality of the coal bed itself. Is the overburden hard, and will it require drilling and shooting? How many yards of it will have to be handled to produce a ton of coal? Will it remain in place when .put in the spoil bank, or will it spread and run back into the pit? Are the drainage problems serious, and what will it cost to handle the water? Does the coal have bad dips, and what will be the grades and curvatures for haulage? These are a few of the physical problems that confront the prospector, and they can be ascertained only by adequate and careful drilling and engineering of the property to be considered. The engineer is an ever-present necessity, not only in the prospecting but in the daily operation of the property after it has' been approved and developed. The first step in operation after the location of the tipple is the contouring of the surface to be stripped and the laying out of the pits for operation, having in view again adequate room for spoil, drainage, haulage and other problems. If the overburden is hard, as much of it is in the larger stripping areas, it must be drilled for shooting with churn or well drills, the holes continuing from the surface down to or near the coal bed. The location of these holes should be made, and marked with stakes, by the engineer, acting in conjunction with the shooting foreman. The usual practice is to drill holes 6 in. in diameter, although the present tendency is to increase the diameter of these holes so that they will hold, without springing, a larger charge of explosive. With the use of the old method of shooting, the holes were sprung or chambered several times with charges of dynamite, and in the cavity thus made, the explosive was placed, largely at the bottom of the hole; but with the use of liquid oxygen as an explosive, and with the later

Jan 1, 1931

RESEMBLING in some respects the enterprise at R Chuquicamata is that of the New Cornelia Copper Co. at Ajo, Arizona. Controlled from its inception by the Calumet & Arizona Mining Co., New Cornelia became a unit of the Phelps Dodge Corporation when the latter absorbed the Calumet & Arizona company in 1931. Both Ajo and Chuquicamata are situated in low mountains in extremely arid desert country. Both ore deposits consisted-the past tense is used advisedly because the oxidized ore has nearly all been mined at Ajo-of a horizon of leachable oxidized ores overlying sulphide or concentrating ore. The principal technical problem in each case was the development of a method for treating the oxidized ore. In both instances the capping of waste rock was comparatively thin and power-shovel mining in open cuts was the obvious method of exploitation. Nature had smiled on neither place in the matter of climate. Though Ajo does not have the persistent winds for which Chuquicamata is notorious, the comforts of living are largely artificial. And it is only fair to emphasize that at each place the mining companies have achieved remarkable success in providing these comforts. Of course, in point of size New Cornelia must be content with the inferior role. From May, 1917, when production was started, to the middle of June, 1930, the company leached 16,368,000 tons of oxidized ore, thereby virtually exhausting the ores of this class. Up to the same date, about 15,000,000 tons of sulphide ore had been mined, and a rough estimate gives 170,000,000 tons remaining in reserve. The total tonnage does not loom very large in comparison with Chuquicamata's billion tons; but it is exceeded by similar figures for only four of the Porphyry group.

Jan 1, 1933

By Fred T. Greene

Most of the recent discussion of the mineral land law published in the Transactions is in the abstract—an exception being Mr. Goodale's paper, The Apex Law in the Drumlummon Controversyll which illustrates in concrete instances many of the practical disadvantages of what Dr. Raymond has called "The Law of the Apex." The present paper, it is hoped, may serve a similar purpose, emphasizing the necessity for a change in our mining laws, and bringing home to mining engineers some of the defects and dangers of our present code. There are many storm centers of "apex litigation" in the Rocky Mountains; and not the 1east. of them is the Wardner camp, where such litigation has been almost continuous since 1892, and the end is not yet. In their decisions, the courts have accepted the claims of the litigants that the "Wardner vein" is a broad zone varying from 250 to 500 ft. in width at the surface. This is the simplest theory which could have been advanced, and probably decreased, rather than augmented, the number of contests; in fact, every one of the claim owners seemed to feel that the greatest advantage would accrue to him if this theory were adhered to. The dominant structural feature of the Wardner vein is a persistent fault, striking N. 40' W., dipping about 40" to the southwest and called the "Wardner foot wall." Fig. 1 is a composite of two adjacent cross-sections of the vein and is a fair representation of the relative size and shape of the orebodies and their relation to the "Wardner foot wall." The country rock is a comparatively thin-bedded sericitic quartzite which has an average strike of N. 80" W. and dips at high angles to the north and south. The movement on the Wardner foot wall is apparently normal, and there has been more or less brecciation on either side of it; but as the moving mass was that above the foot wall, the brecciation has been more complete on that side, and has extended farther from the plane of movement. Many minor faults, generally of insignificant extent, resulted from the movement along the Wardner foot wall. Most of these were

Jan 1, 1916

By AIME AIME

IN accordance with the custom of recent years, the Institute joined with the Western Division of the American Mining Congress in holding a joint meeting at Joplin on Sept. 28, 29 and 30. Actually the meeting might be said to have begun on the 27th, since the Engineering Education Committee held two sessions on that day, which are reported on another page. In addition to these sessions there were informal gatherings in the Hotel Conner, which was the headquarters, on the golf links and elsewhere of all those who had arrived by Sunday morning. The technical sessions were formally opened on Monday morning by Robert E. Tally who, after suitable preliminary remarks, introduced A. Scott Thompson, of Miami, Okla. Mr. Thompson in welcoming the visitors to the Tri-State district said that it had come to be known as a poor man's country and at the present price of zinc did not find it difficult to live up to its name. He also referred to the work Mr. Tally had done for the stabilization of the mineral industry. H. Foster Bain, in responding to this address for the Institute, said that mining men generally felt at home in Joplin, that the solutions of their problems and the general practice that had been developed in the district were not only of great interest to them, but that visitors could learn much

Jan 1, 1931

By R. Schuhmann

As a response to rapidly growing specialization in various branches of metallurgy, it is proposed that undergraduate education in metallurgical engineering should be built up around four principal scientific themes: 1—thermodynamics, 2—structure, 3—mechanics, and 4-—rate processes. THE following quotation from a recent article by von Bertalanffyl describes very well the situation which today challenges curriculum designers in all branches of science and engineering: "Modern scientific education is presented with a well known dilemma. The amount of facts in modern science, and in any of its smallest branches, is enormous. Life in general, and the academic curriculum in particular, is short. The abundance of factual data, as well as the intricacy of modern scientific techniques, experimental and theoretical, necessitates utmost specialization. This specialization, unavoidable though it is, involves serious danger for both the education of the scientist and the social function of science. "In so far as the advancement of science is concerned, history shows that interconnection of different fields and problems is a most important basis of progress. Many of the paramount achievements of science arose on borderlines, and from the synthesis of formerly separate fields . . ." Specialization in subfields of metallurgy has become a serious educational problem only in about the last decade. The growth in specialization, almost as a necessity, has paralleled the rapid growth in metallurgical knowledge during this period. Moreover, in planning future educational policies, the educator must be concerned not only with the rate of increase in metallurgical knowledge and with the concomitant rate of increase in specialization, but also with the second derivatives, that is, with the rates of increase of the rates of increase. These second derivatives are positive and large; the growths being dealt with are self-catalyzing, or like a chain reaction. As a measure of specialization, the length of the list of different kinds of metallurgies can be considered, the kinds of metallurgy which represent one person's particular interests and those of other practicing metallurgists. To start with, there are physical metallurgy, process metallurgy, and mineral dressing, then mechanical metallurgy, metal processing, foundry metallurgy, corrosion, solid state physics, high temperature metallurgy, welding, powder metallurgy, nuclear metallurgy, etc. Each of these fields is growing so rapidly that any one metallurgist can hope at best to keep up to date in only one or two. What is the impact of all these "metallurgies" on metallurgical education and metallurgical curricula? In answering this question, it can be said, first, that educators have resisted fairly well the temptations to split up metallurgy, with different curricula, different options, degrees with different labels, and the like—degrees are still given in plain Metallurgy and Metallurgical Engineering. In other ways, though, the pressures of specialization have had noticeable effects. There is a tendency to think of these "metallurgies" as the important subdivisions of Metallurgical Engineering and to work up

Jan 1, 1956

By F. A. Howard, R. T. Haslam

In a broad sense automotive fuel is simply fuel in general and includes coal, coke, wood, charcoal and gas, in addition to the full range of liquid combustibles. All of these are actually used, or have been used, commercially to some extent as fuel for automotive vehicles. The steam lorry burning coal and coke is a common sight on the roads of England. The fact that these coal-fired steam lorries have a distinct advantage in taxes over the conventional gasoline-driven lorry probably explains the survival of this vehicle. The omnibus, or charabanc, operated by city gas carried in a balloon container on the roof, was also at one time a common sight in England, although not as common as the ubiquitous steam lorry. These gas-operated vehicles have, however, disappeared from the streets in recent years, and probably owed their existence entirely to war conditions. In France one of the largest motor vehicle manufacturers had last year more than 30 trucks equipped with regular gasoline engines in service in the Parisian area operating on producer gas obtained from a small gas producer mounted on the running board of the truck. Both wood and charcoal have been used in these gas producers. The authors were interested enough in this unique commercial development to spend some time examining the apparatus used and inquiring into the success which it had met. The picture is by no means an impossible one purely from the standpoint of practicability, but there is no doubt of the soundness of the conclusion that this is not a development which has any present important significance. Powdered carbonaceous matter, coal, coke or lignite, has been used experimentally in special forms of internal combustion engines, but so far as is known, these have never been applied to automotive practice. Range of Liquid Combustibles In the field of liquid combustibles the full range has been exploited to some extent. Heavy residual fuel oils from petroleum have been

Jan 1, 1928

By Geo. H. Ashley

THE present critical state of the supply, distribution, and utilization. of coal and the necessity for pooling and zoning coals calls renewed attention to the lack of any fully adequate classification of coal. In the past coals have been classified as anthracite, semianthracite, semibituminous, bituminous, subbituminous coals, and lignite, and a few special types, such as splint coal and cannel coal. But under the term bitumi¬nous coal are included a great variety of coals differing markedly both physically and chemically. The term subbituminous coal covers as great a range of chemical differences. In order to distinguish these varieties of bituminous coals it has been customary to designate coals by names derived from the place where mined, or by the name of the bed from which it is mined. Thus, in the market reports, coals are quoted as Pocahontas coal, New River or Sewell coal, Moshannon coal, Ohio coal, Williamson County coal, Jellico coal, and so on indefinitely, no limit being set as to the boundaries of the area to which a given name is applied. Nor is there any scale by, which the coal from one place may be compared with the coal from some other district or some other bed. On the one hand, coals from the same district may be quite distinct and sell at very different prices or coal from the same bed may differ greatly in different districts; on the other hand, coals from different states may be so similar physically and chemically that one could replace the other in practical use without any appreciable difference in service.

Jan 8, 1919

By E. H. Crabtree, T. C. King

The ferrosilicon grinding unit at the Central Mill of the Eagle-Picher Mining & Smelting Co. near Picher, Okla., was completed in March 1947. The object of the plant was to grind pigs of ferrosilicon, having a size of approximately 1½ by 4 by 12 in. and an analysis of 85. pct Fe and 15 pct Si, to approximately 100 mesh by crushing and wet grinding in a ball-mill classifier circuit. The minus-100 mesh ferrosilicon had formerly been purchased, and was used as medium in the heavy media process for treatment of lead-zinc ores. From the standpoint of dollars and cents, the cost of minus-100 mesh ferrosilicon was roughly $40.00 per ton more than pigs of the corresponding alloy delivered to the mill. Estimated wet grinding costs were considerably below this figure. The possible saving in cost of make-up medium for the cone plant was particularly attractive since, at that time, the plant losses averaged over four tons of minus-100 mesh ferrosilicon per day. Aside from the probable saving on the grinding charge, the need for such a unit was twofold. First, periodic fluctuations in the differential between the top and bottom densities of the cone were thought to be detrimental to metallurgy. There was little doubt that an intermediate differential existed at which the heavy media separa- tion was most efficient, representing a compromise between concentrate grade and tailing loss. Furthermore, if a finer, but considerably cleaner, medium could be obtained, there was the possibility that the differential could be decreased without increasing the viscosity, or conversely, the viscosity of the medium decreased without increasing the differential. Preliminary to experimental work aimed at pegging the cone differential and circulating medium viscosity at whatever values were found to be most efficient, it was essential to have control over both the nonmagnetic content of the medium and the particle size of the contained ferrosilicon. The latter was possible by means of a grinding unit at the mill. Second, whereas the ferrosilicon alloys are made by a number of manufacturers, only two, to our knowledge, grind it in any quantity for use in heavy media plants. For all practical purposes, the Central Mill was limited to one source of supply, a particularly vulnerable position. In case the supply was cut off, it was thought that pigs of the 85 pct Fe, 15 pct Si alloy could be obtained elsewhere, providing means of grinding them was available. There was no published information available covering wet grinding of ferrosilicon. Dry grinding in batch mills and in continuous mills with air classification was being practiced, but the cost of grinding was excessive and the dust condition objectionable. It appeared that primary and secondary crushing was no particular problem, providing heavy duty equipment was used;

Jan 1, 1949

By S. E. Bretherton

(San Francisco Meeting, September, 1915) DURING the year 1878-79, Anton Eilers, who was then interested in the lead smelting and refining business near Salt Lake City, Utah, made a somewhat radical departure from the regular practice at that time, which was to use but little lime in the slag, with a high percentage of iron. Lime was not only a cheaper flux than iron, but it enabled the metallurgist to make a more siliceous slag, an economical advantage in smelting where the smelting companies had to purchase either iron or lime to neutralize the excess silica, and penalize the ore shippers accordingly. The larger amount of both lime and silica in the slag also made it of lighter specific gravity, and a better separation of the metals and mattes was secured. This change in the formation of slags for lead smelting was brought about by Anton Eilers, prior to the Leadville mining excitement of 1879. We must also give Mr. Eilers credit for the general introduction of the hollow water-cooled cast-iron jacket for the blast furnace. Again referring to the use of more lime and less iron in the formation of slags,. there is no doubt but that it prevents the formation of a great many so-called "sows" in the lead crucible, such as were made in the early history of lead smelting in the Rocky Mountains; these sows consisted of lead, iron, arsenic, sulphur, copper, and other metals, including gold and silver, mixed with unconsumed fuel, and often, after vain attempts to cut them up or melt them to a suitable size for handling, were buried in the slag clumps to get them out of-sight. Another advantage derived from the adoption of high-lime slags. when smelting ore containing arsenic is the production of less speiss (a by-product heavier than matte, resulting from careless operation of the furnace, the lead being driven out of the crucible and sows built up). This speiss, while usually not as rich in precious metals as matte made at the same time, is too valuable to be thrown away; but it is difficult to treat, and it was thrown away or piled on the slag clumps in the pioneer clays of lead smelting in this country.

Jan 8, 1915

By W. A. Backofen, F. de Kazinczy

FRACTURING under conditions of particular interest is identified with the junction of curves relating tensile yield and fracture stresses to test temperature; the intersection point gives the lowest stress, for brittle fracture (at the ductility transition temperature). An expression for is found in Cottrell's brittle-fracture analysis, Eq. [15],1 while measurements of this stress and temperature have been reported for a low-carbon steel heat treated to differ-

Jan 1, 1962

By C. F. Willis

The time is no longer when a man can act as an independent unit; the appreciation of the interdependence of one man upon another has emphasized the importance of the social unit. Epidemics have made us recognize that even a man's health is not distinctly his own to control as he pleases. The physical examination of workmen previous to employment started with an effort to prevent the spread of tuberculosis, for tuberculosis may be detected in its early stages and cured. But it was soon found that many other diseases were detected and the saving of lives made possible. The physical examination does not mean the elimination of the unfit—on that basis it would utterly fail—but rather the measuring of a man's physical fitness and placing the man where he can do the best for himself, his fellow worker, and the company. Industry as a whole cannot expect to live up to the standard of physical examination set for the army, nor should it expect to do so, for in all branches of industry there are types of work that do not require the same amount of endurance as does army work, and the lacing of men with physical limitations in the work for which they are capable permits a higher average of physical fitness for the work requiring physical excellence. Objects of Physical Examination The objects of physical examination are: The early detection of illness, particularly at a time when a full restoration of health is possible; the protection of employees from infection caused by working in contact with contagious diseases; the discovery of a man's physical limitations, in so far as his possibility for rendering good service is concerned; assistance to the safety movement by eliminating association in hazardous occupations with men whose physical condition renders them likely to accident to themselves and others; and the lessening of time lost by sickness. Statistics issued by the United States Department of Labor show that 22.54 per cent. of idleness is caused by sickness, with an average number of 7.71 weeks idle; whereas only 1.66 per cent. is caused by acci-

Jan 1, 1920

By D. M. Dunbar

LONG before Columbus discovered America the original inhabitants toiled in the copper workings of the Andean Cordillera. Their best diggings appear to have been at Chuquicamata, site of the huge present-day open pit owned by the Chile Exploration Co., subsidiary of Anaconda Copper Mining Co. Located in Antofagasta Province of northern Chile, Chuquicamata is in the Atacama desert, high on the western slope of the Andes at 9500-ft elevation. In the Chuquicamata area the Atacama desert merges into the Cordillera. The climate is extremely arid and precipitation, either in the form of rain or snow, is very infrequent. The temperature varies from 50° to 85°F during the day, and drops to 20° to 40° at night. The Antofagasta and Bolivia Railroad, which connects the Chilean Port of Antofagasta with La Paz, Bolivia, passes within approximately 6 miles of the plant. A branch from the main line to Chuquicamata serves the property for outgoing copper and incoming freight. The distance to Antofagasta by rail is 163 miles. Previous to the Inca conquest, this region was inhabited by the Chuco Indians, a small tribe, descendants of the Aymaras and Quechuas. The Incas, whose capital was located in Cuzco, Peru, gradually extended their empire to the south, reaching at one time to what is now central Chile. It is believed that they built crude primitive furnaces on the banks of the Rio Salado where on a small scale they smelted copper ore from Chuquicamata. At the time of the subsequent Spanish conquest, legend has it that Diego de Almagro, on his return to Cuzco in 1536 after his invasion of Chile, obtained from these furnaces metallic copper for horseshoes. During the period from 1560 to 1879 the high grade veins of the Chuquicamata deposit were worked superficially by the Spaniards and Bolivians. The treaty signed after the war of 1879 recognized the sovereignty of Chile over this territory and Chile, realizing the importance of the district, started to develop it in an orderly manner, although only high grade veins were worked. New Process Is Key Reports on the deposit were brought to the attention of Albert C. Burrage, a Boston lawyer and financier, in 1910. Chuquicamata was described as a huge deposit of ore that was not amenable to the usual treatment by concentrating and smelting since much of the copper occurred as oxides. He had been working on a process for the recovery of copper from sulphide ore which involved a sulphating roast, leaching of the roasted product, and pre-

Jan 1, 1952