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By F. L. Wolf

THERE is a tendency on the part of practical foundrymen to accept with reluctance the results of tests on sands, binders, and. such materials made in the chemical laboratory alone. They feel that such tests frequently emphasize and measure properties that are of minor importance and fail to take account of characteristics that are important in determining the value of the material in actual practice. Experience seems to indicate that the most thorough and conclusive, test for any new foundry material is an actual run in the foundry alongside of a standard material of known value. Such a test, however, involves certain difficulties and necessitates certain precautions. It is not always easy to obtain a fair trial for a new material. We all have certain prejudices, which unconsciously affect our judgment to a marked degree. A practical test frequently involves so many workmen, each of whom reacts in a different manner to the test, that; the personal equation becomes very, complex and the true results of the test are obscured. There are times, too, when a thorough experimental trial of a material would interfere too much with the rush of work in a department or would hazard the quality, of the product to such an extent as to make it inadvisable. Under such conditions a laboratory test is advisable before the material is sent into the foundry. These tests should be made as practical as possible and so closely related to foundry practice as to give a true index to the value of a, product for the purpose desired. Core sands and molding sands are as numerous "as the sands of the sea" and vary as much in quality. Old sources of supply are continually failing and new ones must be opened, so that we must continually search for new and better grades of sand. During the past year, the Ohio Brass Co. has developed tests for sands', cores, and binders which bear a close relation to the particular use to which these materials are put in

Jan 9, 1920

By R. J. Mechin

Top-slicing was introduced in the Pachuca district in 1917 by T. C. Baker, at that time mine superintendent of the Santa Gertmdis mine. There then existed 1200 ft. below the surface, lying between the fourteenth and eighteenth levels (a vertical distance of 354.2 ft.) a block of ore having a length of 295 ft. and an average width of 82 ft. and dipping at an angle of 65°. This block lay in the hanging wall of the vein and consisted of highly altered and fractured andesite, cut through with mineralized quartz stringers. On the foot-wall side, 26 ft. of old filling, left by former operators, was of payable grade. Stoping therein was first undertaken by the square-set filling system, but because of the extremely heavy hanging wall and loose dry filling in the foot wall, all square setting had to be accompanied by spiling, which made the operation exceedingly slow and costly. A system of mining was sought that would eliminate the difficulties inherent to the square-set system in heavy ground and that at the same time would effect the desired economies in mining. After several years, top-slicing has met all the conditions most satisfactorily, so that when similar conditions presented themselves in El Bordo mine, this method was adopted with necessary modifications. El Bordo mine is operated by the Santa Gertrudis company, and is situated about two miles north of Pachuca. Because of the diversity of the orebodies, a number of different mining methods are in use, among them top-slicing. Description of Block of Ore Former operators, when mining the original vein, left in the foot wall ore of too low grade to be profitable at the time; also, considerabe low-grade material was sorted out and stored as filling in the stopes. Some pillars were left in place, either for support or because they were not payable. All this has formed a body of ore that can now be exploited

Jan 1, 1925

By G. E. McElroy, A. S. Richardson

"The Bureau of Mines, in cooperation with the Anaconda Copper Mining Co., has conducted a series of experiments an air measurement in fan-pipe installa¬tions in a Butte mine during the fall and winter of 1922-3. The chief purpose was to determine the friction factors for different types and sizes 3f fan piping, but much attention was devoted to methods of air measurement, not only with respect to the methods used for friction factor tests, but also to com¬parison with other methods.The air flow was measured simultaneously at two points 380.6 feet apart in six different fan-pipe installations, each over 500 feet in overall length, in a rock cross cut adjacent to an air shaft,The air pressure was regulated by two sinoco multivane fans, driven by 7 ½ h.p. motors, the fans being connected in tandem so that one discharged into the intake of the other through a short connector and the latter discharged into the line through a straight connection equipped with a honeycomb of 4-inch squares or S radial vanes to prevent spiral flow of air, At each point where it was desired to measure the air flow, measuring sections equipped with piezometer rings pierced for easy insertion of pitot tubes, thermometers, etc. Piezometer static pressures were used in all the tests as standard, and dynamic or total pressures only were obtained with the pitot tubes, except for purposes of comparison.The tubes had special guide blocks, designed especially for underground work. To insure greater accuracy two tubes were used simultaneously, in order to obtain the velocity pressure at the center of the section simultaneously with that nearer the circumference, so that the mean velocity would be determined as accurately as possible. The tubes were held in proper place by means of flat guide boards. Velocity pressures were measured in manometers."

Sep 1, 1923

By J. W. Halley

Copper has frequently been recommended as an alloying element for steel and the precipitation-hardening of steels containing from 1 to 2 per cent copper has been studied by a number of investigators. The straight copper steels, however, have not been used extensively and little advantage has been taken of the precipitation-hardening of complex steels containing appreciable amounts of copper. It is difficult to produce a satisfactory surface on the straight copper steels and undoubtedly this has discouraged their use. During recent years a number of steels containing enough copper to make them susceptible to precipitation-hardening have been put on the market. These steels belong to the group usually referred to as "low-alloy high-tensile " steels. They were designed for use in the " hot-rolled" condition; transportation equipment and large structures that cannot be readily heat-treated have been their chief application. Little emphasis has been placed on the possibility of strengthening those containing substantial amounts of copper by precipitation-hardening. The present investigation was undertaken to determine the precipitation-hardening characteristic of one of the "low-alloy steels." Previous Work The first complete study of the effect of time and temperature on the precipitation-hardening of plain copper steels was made by Nehll in 1930. At about the same time Bucholtz and Koster2 studied copper-chromium steels but did not determine the relation between time and temperature to produce maximum hardening. Later, Smith and Palmer3 determined the rate of hardening at various temperatures for two I per cent copper steels containing different amounts of carbon. Their tests indicated that the higher carbon content decreased the rate of hardening. They made tests on many steels containing other alloying elements in addition to copper, but did not determine the time-temperature relationship for maximum hardening for any of the complex steels. Norton,4 in studying the limit of solid solubility of copper in iron, determined the time for maximum hardening of a 2.06 per cent Cu iron

Jan 1, 1940

By Foster Bain

THOUGHTFUL people have raised questions as to how long nature's bank could continue to accept our drafts. These questions came to the fore so persistently, and there were so many evidences -such as the failure of natural gas in Indiana, the increasing scarcity of lumber in the Lake Superior region, the progressive sterility of Southern farm lands, the choking of the Sacramento River by tailing-point-ing to possible danger from overdraft or to misuse of resources and opportunity, that President Roosevelt called a conference which assembled at the White House on May 13, 1908, to consider these and related questions. This, the first great Conservation Congress, had a wide and beneficial influence on the thought of the world. It profoundly influenced the course of succeed-ing events and, while even yet there are sharp dis-agreements as, to the wisdom of much that has been done in the name of conservation, I believe that thoughtful men, and engineers especially, agree that the time had come when sharp attention was properly called to the waste that accompanied development of our resources. RESOURCES LARGE BUT NOT INEXHAUSTIBLE In 1908 there was a surprisingly large number of men, who should have known better, prepared to argue that our resources are "inexhaustible." No competent mining engineer, of course, believes that, as regards minerals at least. They may be, and, in most cases, fortunately are, large; as to many of them our knowledge is too general to permit measuring the reserves; but we know now, and I think the public appreciates, that there is a limit to our supply of gas, oil, coal, iron, and metals. Indeed, with the inten-sive study made necessary to meet the demands of the war, and the more careful accounting required by the newer systems of taxation, depletion has become a common word, and that mines are wasting assets has become a platitude.

Jan 8, 1922

By C. A. Hartnagel, D. H. Newland

Most of the petroleum produced in New York State is obtained by flooding; that is, water drive. No important oil fields have been developed during the past 30 years, nor does there seem much hope that the productive oil areas will be substantially enlarged in the future. There is some prospect that additional supplies may be obtained by deeper drilling, but deep tests for gas to the Oriskany sandstone in some of the oil-producing areas have been without results so far as any discoveries of oil are concerned. Although the flooding method had been made legal in 1919, and some floods had been in operation previous to 1921, that year marks the beginning of a rapid increase in oil production by the new method. The flush production of oil in New York was in 1882, shortly after the discovery of the Richburg pool in Allegany County. The oil production in that year amounted to 6,685,000 bbl. The 1937 production of 5,478,000 bbl. was the largest since the flush production of 55 years ago. The effectiveness of water-flooding for increasing oil production from the old New York fields is shown in Table 1. Table 1.—Production of Oil in New York since 1921 Year Barrels Year Barrela 1921 988,000 1929 3,377,000 1922 1,000,000 1930 3,647,000 1923 1,250,000 1931 3,363,000 1924 1,440,000 1932 3,508,000 1925 1,695,000 1933 3,181,000 1926 2,242,000 1934 3,804,000 1927 2,603,000 1935 4,236,000 1928 3,377,000 1936 4,633,000 1937 5,478,000 The area of the New York oil fields is about 60,000 acres. It has been estimated that not over one-fourth of the area is being flooded. Very little of flooded territory has ceased to produce. Some leases flooded by the early, less scientific methods are being again subjected to the water

Jan 1, 1938

By E. W. Owen, John G. H. Crump, Peter P. Gregory

.Although oil Production in West Texas in 1939 reached the highest figure for any year since the inauguration of proration, drilling activity continued in the decline that had commerlced the previous year. Production totaled 79,469,341s bbl. of oil during 1939 as compared with 71,257,541s bbl. in 1938 and 75,743,000 in 1937. The number of wells completed in 1939 was 1850, compared with 2045 in 1938 and 2806 ill 1937. Several factors combined to cause the decrease in drilling activity, principally the contiriued increase in the length of time required to obtain a return of invcstment and the scarcity of important new discoveries during the past two years. Of the 1850 completions 1638 resulted in oil wells, 4 were gas wells, 168 were dry holes and 40 were abandoned locations; 1990 new locations were made during the year. The ratio of dry holes to producing wells completed was one dry hole to each 9.75 oil wells, compared with one dry hole to each 7.48 oil wells completed during 1938. This large decrease in dry holes was due to a marked decline in the number of wildcat wells drilled, there having been only 120 wildcat completions during 1939. In addition to the lessened exploration work, the deeline' in activity was largely accounted for by the slowing up of operations in the older pools of Ector, Howard and Winkler Counties. Ector County, which had led West Tcxas in 1938 with 622 new oil wells, furnished only 485 producers in 1939, but was still the leader for the West Texas district. The largest gain in activity was in Yoakum County, whew 350 oil wells were completed in the Denver-Wasson field against 152 during 1938. Most of the older oil fields have been almost completely drilled up, only a few new producers still being completed from time to time in

Jan 1, 1940

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 L. H Levenson, Charles S. Barrett

The orientation of metal crystals and grains, both large and small, can be detcrmined conveniently and accurately without the use of X-ray apparatus. This seems to be appreciated by so few metallurgists that it may be useful to explain in detail the method we have found most satisfactory in the laboratory—the reflection of light from crystallographie etch pits. This note includes a description of a suitable inexpensive instrument and instructions for etching various metals and for plotting the data. As the stereographie projection is used to facilitate handling the data, this note may he considered as an appendix to an earlier review of the metallurgical uses of the stercographie projection.' Various methods involving etch pits have been used by other investigators. Bridgman's method2 consists of attaching the specimen to a sphere (a transparent sphere is convenient4 , holding it at arm's length, and marking a spot on it when it has been turned so that the eteh pits reflect light into the eye of the observer from a lamp standing behind him. It has an accuracy of about 2" and is extrernely rapid. A greater accuracy can be obtained by having the reflected light fall on a screen, as has been done by Czochralski,5 Chalmers,6 and Schubnikov.7 All of these methods have been intended for undeformed single crystals. Tammann and his coworkers3,8 developed a method for estimating the number of grains in a polyerystalline aggregate having orientations in a given region of the stereographic triangle and thus obtained statistical information about deformation and reerystallization textures. While the method has had some use in recent years,9 it is not applicable to the majority of problems in physical metallurgy. Smith and Mehl10 determined orientations by plotting the directions of the sides of individual etch pits on a stereographic projection. The accuracy is limited to about 3" and the method requires careful polishing and high magnification.

Jan 1, 1940

By Walter Bradley

MINING by hydraulic process of the important gold-bearing gravels of the Sacramento Valley in the basins of the Yuba, Bear and American rivers began in 1853, and continued at an ever-increasing rate for 30 years. In its most active days it reached an annual production of $15,000,000, and averaged $10,000,000 per year over the 30 years. During that period no provisions were made to prevent the debris from being dis-charged into the water courses, and ultimately large quantities of silt, sand and gravel were washed down to the lower valleys; filling channels, causing overflow of agricultural lands and difficulty in maintaining navigable depths in the Sacramento River. Agitation and suits filed because of these damages finally resulted in the injunction decision of Judge L. B. Sawyer,1 in the U.S. Circuit Court, Jan. 23, 1884, which closed down practically all hydraulic mining operations not having means to restrain their debris. In 1893 (approved March 1, 1893), Congress passed the act introduced by Representative Anthony Caminetti, of California, creating the California Debris Com-mission, composed of three officers assigned from the Engineer Corps of the U.S. Army, and since that time it has been legal and possible within the drainage systems of Sacramento and San Joaquin rivers to conduct hydraulic mining of gold-bearing gravels behind dams built under this commission's permit and supervision. In the watersheds of the Trinity and Klamath rivers, which flow directly to the Pacific Ocean and do not affect navigation or agriculture, operating permits from the California Debris Commission are not required. There is a measure of restriction there, however,. through what is known as the Trinity and Klamath River Fish and Game Dis-trict. Chap. 215, Stat. 1931, in order to secure relatively clear water for the fishing season, provides that between July 15 and October 15 each year there must not be discharged into these rivers debris that will cause a turbidity greater than a content of 50 parts per million in the

Jan 1, 1936

By E. L. Larison

DURING the early years of the present century a notable interest appeared in American industry in the matter of recovering and render-ing profitable byproducts of manufacturing operations. Among the byproducts of reduction of sulfide ores in many plants large amounts of sulfur dioxide gas were available. In certain instances the concentration of SO2 in the gases evolved was, or could be made, sufficient to make them suitable for manufacturing sulfuric acid. At the Anaconda Reduction works such a condition existed. Large tonnages of copper concentrate were being roasted and the roaster gases were available and suitable as a source of sulfuric acid. Earlier work on a large scale at Martinez, Calif., and in the Ducktown region, Tennessee, had shown the feasibility of manufacturing sulfuric acid from the SO2 contained in gases arising from the reduction of copper sulfide ores. In California and Tennessee the acid found a ready market in manufacture of fertilizers, while the situation regarding disposal of the sulfuric acid was quite different at Anaconda. No local use for acid existed, and a commodity of such low value could not stand freight charges to consuming centers. There was a very large accumulation of sand tailings from the gravity concentration mill below the plant at Anaconda. This material, made by the comparatively crude methods in use up to about 1915, contained about 13 lb. of copper per ton, largely as sulfide minerals. In 1912 serious research work toward recovery of this copper was instituted and after about two years of laboratory and pilot-plant development, a process for accomplishing it was perfected. This process involved roast-ing the sand tailings, leaching the roasted tailings with sulfuric acid, and throwing out the copper by passing the solutions over scrap iron. Under this plan each ton of sand required the introduction of about 70 lb. of 60° Be. sulfuric acid.

Jan 1, 1934

By Charles S. Barrett, L. H. Levenson

The orientation of metal crystals and grains, both large and small, can be detcrmined conveniently and accurately without the use of X-ray apparatus. This seems to be appreciated by so few metallurgists that it may be useful to explain in detail the method we have found most satisfactory in the laboratory—the reflection of light from crystallographie etch pits. This note includes a description of a suitable inexpensive instrument and instructions for etching various metals and for plotting the data. As the stereographie projection is used to facilitate handling the data, this note may he considered as an appendix to an earlier review of the metallurgical uses of the stercographie projection.' Various methods involving etch pits have been used by other investigators. Bridgman's method2 consists of attaching the specimen to a sphere (a transparent sphere is convenient4 , holding it at arm's length, and marking a spot on it when it has been turned so that the eteh pits reflect light into the eye of the observer from a lamp standing behind him. It has an accuracy of about 2" and is extrernely rapid. A greater accuracy can be obtained by having the reflected light fall on a screen, as has been done by Czochralski,5 Chalmers,6 and Schubnikov.7 All of these methods have been intended for undeformed single crystals. Tammann and his coworkers3,8 developed a method for estimating the number of grains in a polyerystalline aggregate having orientations in a given region of the stereographic triangle and thus obtained statistical information about deformation and reerystallization textures. While the method has had some use in recent years,9 it is not applicable to the majority of problems in physical metallurgy. Smith and Mehl10 determined orientations by plotting the directions of the sides of individual etch pits on a stereographic projection. The accuracy is limited to about 3" and the method requires careful polishing and high magnification.

Jan 1, 1940

By T. S. Hutchinson, C. E. Kemp

The bottom water drive analysis presented by Muskat has been extended to include fields with wider well spacings. Curves are presented from which volumetric sweepout, water-oil ratio, and rate relations may be calculated. The effects of non-unity ratios on sweepout eficiency and productivity decline have been studied by an approximate method. Also, the effect of gravity on volumetric sweepout has been approximated for a particurlar geometry. INTRODUCTION The purpose of this paper is to report work done in applying the analysis of bottom water drive reservoirs given by Muskat1 to a larger class of reservoirs, to extend this analysis to include the effects of gravity and non-unity mobility ratios in an approximate manner, and to investigate the rate of decline of productive capacity. The bottom water drive type reservoir is one where the oil is underlain by a water zone of sufficient thickness that water movement is essentially vertical. This system is defined in more detail in the appendix and a one well element is shown diagrammatically in Fig. 1. Muskat obtained solutions to the equations describing the volumetric displacement efficiency of idealized bottom water drive systems by assuming that gravity effects due to differences in density betwecn oil and water were negligible and that the mobilities of oil and water were the same. If either of these assumptions is not made, the complexity of the system makes an analytical solution well nigh impossible at the present stage of mathematical development. Coles and Stade' developed an approximation to consider these factors. The authors have refined approximations, starting with the same basic assumption, which should give a somewhat quantitative picture of bottom water drive performance when mobilities are not equal and the effects of gravity are not negligible. The results of these approximate calculations can then be used to obtain the decline in well productivity as the field is depleted.

Jan 1, 1957

By H. H. Stoek

A STUDY of American coal mine practice shows two of its distinctive features to be: A greater number of accidents per thousand employees than in any of the other leading coal-producing countries; a much greater percentage of the coal lost than is the case in any of the other leading coal producing countries. Although our subject is mainly concerned with the second feature, any consideration of mining methods should include safety, efficiency, and economy or costs. If in defense of our wasteful mining the argument could be offered that it was necessary on account of safety, and that it is carried out with less loss of life than is the case in other countries the plea for conservation of coal could not be so strongly urged. But when we are wasteful of both life and property, the subject merits more consideration than it has received. Some coal operators will doubtless say that the unit of accidents should be the number per million tons produced rather than per thousand employees, for by adopting this unit America probably stands in the lead rather than the lowest among the countries. However, vital statistics are not usually so expressed by other governments, by life and accident insurance companies, or in other industries, and it is merely begging the question and attempting to bolster up a bad condition to adopt a peculiar unit for the statement of our accidents. For many years the statement was made by various agencies, and was unchallenged, that "For every ton of bituminous coal mined in the United States a ton had been lost in the way of pillars left in the mines." This statement was undoubtedly true for many years, and although some progress has been made in the past decade looking to a higher extraction, and in some districts very decided progress, the loss is still great; and, although no exact data can be given, it is probable that for the United States as a whole at- least one ton is lost for every two mined.

Jan 2, 1922

By A. M. Starfield

The study of strain waves in rock over the past decade has, for the most part, been an investigation related, but not applied, to rock blasting; the design of rock blasts has proceeded on a basis that is independent of strain wave research. This duality is reflected in the paper by Dr. Clark.1 While the greater part of the paper is devoted to a discussion of spherical waves in elastic and visco-elastic media, it is in an entirely unrelated section, the section on scaling and cratering, that the practical approach to rock blasting is found. Work done by the U. S. Bureau of Mines, as described in the paper by Duvall, Atchison, and Fogelson,2 has established a correlation between crater dimensions and the peak compressive strain in the rock. Strain wave measurements have thus been used to compare explosives but have not, as yet, been applied to the planning of a production round once an explosive has been selected. The optimum burden, for instance, is still determined either by experience, empirical formulae (e.g. that of Langefors 3), or a cratering experiment and the theory that has been developed around that proposed by Livingston.4 Even then there is some ambiguity in applying deductions from short, concentrated explosive charges to the long charges often used in practice (although Bauer 5 reports doing this with considerable success) and wave theory has until recently thrown no light on this problem, being confined, with only a few exceptions, to spherical charges. The hesitation in applying strain wave theory has probably been due to two questions that have not been answered satisfactorily: just how important is the strain wave in rock breakage, and if it is important, under what conditions will the wave break rock? This paper is an attempt to answer the first question, to avoid the second question by an admittedly oversimplified assumption, and then to investigate the implications of this assumption for blasting with long cylindrical charges.

Jan 1, 1967

By M. J. Marcinkowski, R. M. Fisher

The flow stress-grain size relationship has been determined at room temperature in both a disordered and a fully ordered FeCo for plastic strains up to 30 pct. The results are in agreement with a Hall-Petch relation of the type given by Of =a,+kd-1/2 where of is the flour stress and a, increases mono-tonically with increasing strain to a maximum value which is much higher for the ordered than for the disordered alloy. The slope, k, is found to increase FOLLOWING the original work of Halll and petch relating the effect of grain size to the lower yield stress of iron and steel, it has been generally found that the yield stress oy.s. of polycrystalline metals with strain to a maximum and then decrease for both ordered and disordered alloys. However, k for the ordered alloy is in general higher than that for the disordered alloy and the critical strain for k max somewhat larger. All of these observations can be satisfactorily accounted for quantitatively and in some cases semiquantitatively by using a slip band-grain boundary intersection model, and by taking note of the fact that, in general, moss slip, while quite common in the disordered alloy, is extremely difficult in the ordered alloy. obeys a relation of the form oy.s.=a0+kd-1/2 [1] where a, and k are constants and d is the mean grain diameter. For convenience, and in accord with prevailing custom, Eq. [I] will be referred to simply as the Petch relation. Tjerkstra3 and Armstrong, Codd, Douthwaite, and petch4 showed that the flow stress af of iron or steel measured at strains of up to at least 20 pct also obeyed a relationship of the type given by Eq. (11. The latter investigators have also shown that Eq. [I] applies to fcc and hcp metals and alloys.

Jan 1, 1965

By E. L. Larison

DURING the early years of the present century a notable interest appeared in American industry in the matter of recovering and render-ing profitable byproducts of manufacturing operations. Among the byproducts of reduction of sulfide ores in many plants large amounts of sulfur dioxide gas were available. In certain instances the concentration of S02 in the gases evolved was, or could be made, sufficient to make them suitable for manufacturing sulfuric acid. At the Anaconda Reduction works such a condition existed. Large tonnages of copper concentrate were being roasted and the roaster gases were available and suitable as a source of sulfuric acid. Earlier work on a large scale at Martinez, Calif., and in the Ducktown region, Tennessee, had shown the feasibility of manufacturing sulfuric acid from the S02 contained in gases arising from the reduction of copper sulfide ores. In California and Tennessee the acid found a ready market in manufacture of fertilizers, while the situation regarding disposal of the sulfuric acid was quite different at Anaconda. No local use for acid existed, and a commodity of such low value could not stand freight charges to consuming centers. There was a very large accumulation of sand tailings from the gravity concentration mill below the plant at Anaconda. This material, made by the comparatively crude methods in use up to about 1915, contained about 13 lb. of copper per ton, largely as sulfide minerals. In 1912 serious research work toward recovery of this copper was instituted and after about two years of laboratory and pilot-plant development, a process for accomplishing it was perfected. This process involved roast-ing the sand tailings, leaching the roasted tailings with sulfuric acid, and throwing out the copper by passing the solutions over scrap iron. Under this plan each ton of sand required the introduction of about 70 lb. of 60° Be. sulfuric acid.

Jan 1, 1934

By V. K. Handa

Sterlite Industries (I) Ltd. started its copper smelter in 1996 and worked through the common problems associated with smelter start-ups. Specific issues in the converter area included converter blower IGV problems, punching machine reliability, converter spitting, back collar burning, ,and short converter campaign life. With a very young and dedicated team of engineers and technicians, smelter management assigned teams of three to four members to work scientifically and systematically through each major problem area to recommend and implement appropriate solutions. The converter mouth was redesigned with respect to tuyere and metal height to eliminate spitting and back collar burning. The air line was changed in places to reduce the pressure drop. A new back-up compressed air line and vessel was installed to prevent tuyere blockage in the event of a blower trip or power failure. The converter mouth liners and bricking around the mouth was modified to eliminate metal leaking through the pouring lip Modifications to the punching machines were made to address specific problems and preventative maintenance practices were further streamlined and reinforced to ensure 100% availability of hot metal cranes, converter blowers, punching machines, and ID fans. Matte availability and matte temperatures were improved by streamlining the upstream ISA and Rotary Holding furnace areas. Implementation of a detailed training program for the converter operators significantly improved the operation and morale. Water-cooled double hoods and a third converter were installed as part of the smelter modernization plan. The new hoods dramatically improved hygiene in the crane aisle while the addition of the third converter posed new challenges for the same motivated group of crews with respect to flip flop operation to keep the idle converter hot and to maximize in-stack time, managing crane/ladle logistics, and managing revert generation. This paper describes the converter operation's journey from the initial days of long blowing times and large revert accumulations to present operations with two converter flip flop operation, and also describes the team work, constant focus on increasing productivity and reducing costs, and benchmarking.

Jan 1, 2002

By B. W. Adams, R. W. Shilling

9.4-1. Basic principles. DESCRIPTION AND BASIC FUNCTIONS. The concept of inclined skip haulage is not new. The basic idea has been in use at least 400 years. The system is essentially a steeply inclined railway utilizing a hoist to pull the skips to the top or intermediate positions. Inclined skip haulage is often justified where high lifts would require long hauls for other haulage systems. The basic system types are as follows: 1. Single skip, single drum. This system is a single car pulled by a simple hoist system. 2. Balanced skip, single drum. A system utilizing two cars (skips on cables)--one overwound, one underwound-on a single drum. The dead weight of one skip and cable balances the dead weight of the other. As one skip ascends the other descends between two fixed points. 3. Balanced skip, double drum. This system is an elaboration of system No. 2, except the drums may be disengaged from one another to permit the skips to service various loading and dumping points. The preceding are major classifications subject to numerous variations. These variations may be in the skipway, skip design, loading methods, or unloading methods. A few examples follow: 1. The skipway may be standard or special railroad, an overhead monorail or cable, or a ramp for rubber tired vehicles. 2. The skip, per se, may be of varying dumping arrangements (side, bottom, etc.) or could be the box of the vehicle hauling to the skip. 3. Loading may be accomplished directly from the service unit to skip, through an intermediate loading device (e.g., a pocket), or into bins which feed the skip. Loading may be at more than one point. 4. Unloading of the skip can be simple or complex as required. Dumping may be to the haulage unit, to bins and feeders, or to a crusher and conveyor system. Dumping may take place at more than one point.

Jan 1, 1968

The earliest reference to coal in Tennessee is that by Dr. Walker in 1750 (see p. 18) where he saw it near the present site of Middlesboro. The next reference found is in 1798 when Morse stated, "some of these mountains, particularly in the, Cumberland, or Great-Laurel Ridge, are the most stupendous piles in the United States. They abound in ginseng and coal."' There must have been many places where it was seen in that interval, but nearly as long a time elapsed before Morris, in 1834, said that "fine beds of stone-coal exist in both East and Middle Tennessee."2 In a description of the Dover Iron Works, on the left side of the Cumberland River, a few miles above Dover, in Stewart County, it was said that "80 hands were employed in digging and transporting stone coal" and that the "plant had been running at least since Oct. 2, 1834."3 While doubtless coal had been used locally, this is probably the first use of it commercially in the state. The consumption of stone coal was 4,000 tons per year. In this same geological report openings of coal are mentioned near Battle Creek, Marion County, and in Bledsoe and Rhea Counties, where it was being used locally by blacksmiths; some other places were being worked near the turnpike road from Kingston to the Crab-Orchard, the product being hauled three miles to the Tennessee River and loaded in barges; farther west in. White County several outcrops were found. In Fentress County, several pits had been opened, the coal being sent down the Obey and Cumberland Rivers, and openings were also seen in Morgan, Anderson, Roane, Warren, Hamilton and Franklin Counties. The writer had hoped to publish an account of the iron works in the state but was unable to obtain the necessary information. He was told by an old iron-master, Mr. E. Embree, that

Jan 1, 1942