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By E. Buehler, R. H. Willens

A Hew melting technique has hem adapted to the rapid quenching of- alloys from the liquid state. The inelting method has no limitations on the alloys investigated for there is no reaction with crucible materials and the most refractory materials are easily melted. The vate of heating is so rapid that alloys which have a high vapor pressure constituent can be melted with a minimal loss in material. Several new superconductovs have been discoveved by vapid quenching of lolten alloys. THE rapid quenching of alloys from the liquid state has led to the discovery of many new metastable phases. The methods initially used were limited to alloys which did not react with crucible materials.1,2 There was also the unmentioned limitation in tem- perature. Alloys with melting points much greater than 2000°C could not be melted in the rapid-quench apparatus. Recently, there have been successful attempts to rapidly quench reactive alloys by Moss et at. and Matthias Moss et al. injected powdered material (325 mesh) into a high-temperature plasma and the high-velocity molten droplets impinged on a cooled copper plate. The technique innovated by Matthias was to melt the alloy in an arc furnace and splatter it against a copper plate by means of a high-velocity gas jet aimed at the melt. I) FAST COOLING APPARATUS The creation of a metastable phase in a given alloy system by rapid cooling from the melt is contingent on the quenching rate. Some alloys require very slow rates while other alloys require the ultimate in quenching rate. At the present time, the vertical-gun technique of Duwez and willens' has demonstrated, in practice, the highest quenching rates and thus the best

Jan 1, 1967

By R. G. Dressler

The design and operation of the Koppers powdered-coal gasifier and its auxiliaries at Louisiana, Mo., are described. This unit was designed to convert 1 ton of coal per hour with oxygen and superheated steam into synthesis gas - primarily carbon monoxide and hydrogen. The first run was made on May 4, 1949. After this, 44 short runs (less than 8 hours each) and 1 long run (lasting 11 days) were made. Total gasification time was 420 hours. The gasifier was not cooled down during the year when these runs were made. After an initial period of test operations and equipment proving, during which 12 runs were made, the effect of numerous variables on gasifier performance was studied. The long run was made primarily to check the equipment in sustained operation. Detailed data from these runs are presented.

Jan 1, 1954

By Arthur C. Green

A group of 13 cities situated in Los Angeles and Orange counties in Southern California is engaged in constructing an aqueduct to carry water from the Colorado River at a point near Parker, Arizona, to a distribution point near Riverside, California. The aqueduct will have a total length of approximately 241 miles, and is designed to deliver 1605 cu. ft. of water per second, or a little more than one billion gallons per day. The aqueduct crosses a barren, desert waste and the project includes approximately 91 miles of 16-ft. tunnel. The large amount of tunnel driving that has been done in this country in the past few years has resulted in some remarkable developments in equipment and methods. The building of the Colorado River Aqueduct,, with its 91 miles of tunnels, has called on the best engineering knowledge in the country. New and better equipment has been designed for all phases of the work, and this equipment has been coordinated and adapted to the various conditions with a high degree of efficiency. The result has been that records for tunnel driving have been set under adverse natural conditions that exceed the estimates for progress under good conditions. All of the tunnels in the main aqueduct, except the Valverde and Bernasconi at the western end, have a finished diameter, inside the concrete lining, of 16 ft. Fig. 4 shows a section of the tunnel with the concrete lining in place. Fig. 5 illustrates the finished tunnel in three typical sections. The standard tunnel grade is 3.432 ft. per mile in the 16-ft. tunnels, but the Valverde and Bernasconi tunnels have a steeper grade and a finished diameter of 15 ft. 3 in. The rough bore of the large main aqueduct tunnels averages 12.95 solid cubic yards of material per foot of advance in timbered sections and 10.76 solid cubic yards per foot in unsupported sections. Tunnel Driving While the Conway mucker has been used on tunnel work for years, a larger and more powerful Conway was designed to meet the require-

Jan 1, 1937

By Samuel Doak

THE utilization of rotary kilns, of the well-known cement type, for the preparation of iron ores, for the blast furnace, has become of considerable economic importance within the past 10 years in certain localities, notably those where the native ores are lean. Such kilns may be used simply for the agglomeration of ores too fine to be charged into the blast furnace (i.e., ores whose loss in the dust catchers is excessive, and whose fineness is detrimental to the working of the furnace), or for the desulphurization of lump and fine ores the sulphur content of which does not exceed 6 or 7 per cent. The desulphurizing action can be combined with that of agglomeration provided the kiln is sufficiently large. Other processes have been developed for the same purpose, but while I am not able to draw a comparison between them by reason of lack of sufficient data, it is safe to say that the kiln, if properly dimensioned for the character of ore to be treated, will compare favorably in its results, both as to economy and quality of product, with any other process. It is not, however, as well adapted for the treatment of flue dust, as is a sintering operation, on account of the large percentage of fine coke contained therein. Any combustible entering the kiln at its feed end renders the process very much more expensive and unsatisfactory on account of the difficulty of controlling the temperature, also because of the rapidity with which long "rings" form, due to the increased heat at the cooler end of the kiln. The greatest value of the kiln at present is in the treatment of pyrites cinder; that is, the residue from pyrites ore after the extraction of the greater part of the sulphur. This cinder, while high in iron content, has too much sulphur remaining in it to be allowed to form a large part of the blast-furnace burden, without further treatment. It will range in metallic iron from 42 per cent., representing a very low-grade cinder, from a domestic pyrites, to 64 per cent. of the residue from the best Spanish ore, and the corresponding silica content will vary from the maximum of about 25 per cent. to 1 ½ per cent. The residual sulphur depends largely on the type of burner used in the original desulphurization. In general, the leanest original ores retain the greatest amounts of sulphur. In

Jan 9, 1915

By O. Cuscoleca

The Austrian plants at Donawitz and Linz were the first to blow steel with high purity oxygen. The paper shows how the process was developed and gives a survey of the results achieved to date. Compared with open hearth steel of equal quality, the obvious advantages of oxygen steel are the low investment and conversion costs. The nitrogen content of oxygen steel is not higher than that of good open hearth steel. Rimmed and killed steel products made by the oxygen process are superior to rimmed and killed steel products made by the best open hearth process. TWO new steel plants using the principle of making steel with high purity oxygen went into operation in Austria, one at Linz (Vereinigte oster-reichische Stahlwerke) in November 1952 and the other at Donawitz (dsterreichisch-Alpine Montan-gesellschaft) in May 1953. An estimated 330,000 metric tons were produced by the two plants in 1953, the first year of operation. In 1954 production by Austrian plants- using the high purity oxygen approach will be raised to 450,000 metric tons. This will be in addition to facilities in Huckingen (Man-nesmann A. G., Düsseldorf, Germany), those planned and under construction at Hamilton, Ontario, Canada (Dominion Foundries and Steel, Ltd.), and elsewhere. It is expected that by 1955 a total capacity of one million tons of high purity oxygen steel will be available. At the close of the last century, because of increasing availability of scrap, open hearth steel production forged ahead at an ever increasing pace. This caused world steel production to rise faster than pig iron production and finally to overtake it. In 1911 65 million tons of steel were produced against 64 million tons of pig iron. World steel production was 209 million tons in 1951, while pig iron output was only 147 million tons. The 1951 breakdown for steel shows 118 million tons made from pig iron, while the balance, 91 million tons or 44 pct of the total tonnage of steel produced, was made from scrap. This increase in crude steel production on a basis of high scrap consumption led to the world market scrap shortage and soaring scrap prices. In the United States and other nations, production of converter steel has fallen far behind that of open hearth steel. The surplus of processing scrap, un-absorbable by converting mills and thus a welcome source for open hearth and electric melting shops in the past, together with regular scrap purchases, no longer can meet requirements of both open hearth and electric steel production in Europe. In addition, recent modification of the basic bessemer process, blowing with oxygenated blast, substantially raised the scrap capacity of these plants. Any further expansion of world steel production will necessitate utilization of self-containing processes in regard to scrap because of the shortage.

Jan 1, 1955

By J. F. K. Brown, E. E. Roecker

For three years The Hudson Coal Co. has used egg anthracite instead of coke in its foundry cupola. It has long passed the stage of being told it cannot be done—the metal would be cold, of poor quality, or the speed of operation would be low. From observation, from use and from test. we know that our metal is about average; the cast iron invokes no adverse comment from the machine shop and the speed suits our foundry requirements. We have there-iore resolved into practice anthracite combustion processes in an industrial furnace formerly using coke, under conditions suitable to our needs. When it comes to translating what we know into use in another cupola, however, where operating conditions may be different, or to explaining why, with seemingly the same conditions in our own cupola, we have attained sometimes a temperature of 2800° in the metal and at another time 2600°, or a speed of 5 tons per hour against 2 35 tons per hour, we cannot do it. We cannot do this because there seems to be an unbridged gap between laboratory ideas on combustion and practical ideas on com-bustiqn, which we have been unable to cross in terms understandable to us as practical consumers. This gap or bridge centers around the problem of how combustion actually takes place; and we believe it is controlled by two factors: (I) the character of the surface of the fuel and (2) the space provided and needed within which the oxygen of the air is allowed to or can act on that surface. It has long been contended on behalf of coke that porosity is an important factor in combustion, although, admittedly, there are two schools of opposing thought on this question, as revealed in technical literature. It has been understood generally that a light, porous coke is the best metallurgical fuel because there are more square inches of carbon exposed to the blast of air, therefore more useful carbon-dioxide reactions can take place in the given space between the entrance of the air and the point where useful work is done. It is now our general idea that the heavier and the harder the coal, the better the metallurgical fuel, provided the surface of that fuel is suitable for fast reaction with the oxygen. Time and Space A cupola is loaded in layers of fuel and iron. The horizontal line where the first charge of iron rests on the coal is the top of the bed coal. With us that is 22 in., usually, above the tuyeres where the air enters. This means 600 lb. of coal. Every subsequent coal layer is 100 to 125 lb. of coal, and that 100 to 125 lb. of coal melts 1000 lb. of iron at around 2700° in the ladle. This quantity of coal represents a 3-in. layer spread across the cupola. The question arises: If this 3 in. of coal will melt 1000 lb. of metal, why was it necessary to use 600 lb., or 22 in., of coal beneath and between the first charge of iron and the air entrance?

Jan 1, 1944

By E. E. Roecker, J. F. K. Brown

For three years The Hudson Coal Co. has used egg anthracite instead of coke in its foundry cupola. It has long passed the stage of being told it cannot be done—the metal would be cold, of poor quality, or the speed of operation would be low. From observation, from use and from test. we know that our metal is about average; the cast iron invokes no adverse comment from the machine shop and the speed suits our foundry requirements. We have there-iore resolved into practice anthracite combustion processes in an industrial furnace formerly using coke, under conditions suitable to our needs. When it comes to translating what we know into use in another cupola, however, where operating conditions may be different, or to explaining why, with seemingly the same conditions in our own cupola, we have attained sometimes a temperature of 2800° in the metal and at another time 2600°, or a speed of 5 tons per hour against 2 35 tons per hour, we cannot do it. We cannot do this because there seems to be an unbridged gap between laboratory ideas on combustion and practical ideas on com-bustiqn, which we have been unable to cross in terms understandable to us as practical consumers. This gap or bridge centers around the problem of how combustion actually takes place; and we believe it is controlled by two factors: (I) the character of the surface of the fuel and (2) the space provided and needed within which the oxygen of the air is allowed to or can act on that surface. It has long been contended on behalf of coke that porosity is an important factor in combustion, although, admittedly, there are two schools of opposing thought on this question, as revealed in technical literature. It has been understood generally that a light, porous coke is the best metallurgical fuel because there are more square inches of carbon exposed to the blast of air, therefore more useful carbon-dioxide reactions can take place in the given space between the entrance of the air and the point where useful work is done. It is now our general idea that the heavier and the harder the coal, the better the metallurgical fuel, provided the surface of that fuel is suitable for fast reaction with the oxygen. Time and Space A cupola is loaded in layers of fuel and iron. The horizontal line where the first charge of iron rests on the coal is the top of the bed coal. With us that is 22 in., usually, above the tuyeres where the air enters. This means 600 lb. of coal. Every subsequent coal layer is 100 to 125 lb. of coal, and that 100 to 125 lb. of coal melts 1000 lb. of iron at around 2700° in the ladle. This quantity of coal represents a 3-in. layer spread across the cupola. The question arises: If this 3 in. of coal will melt 1000 lb. of metal, why was it necessary to use 600 lb., or 22 in., of coal beneath and between the first charge of iron and the air entrance?

Jan 1, 1944

By George S. Rice, O. P. Hood

The need of protecting mines from the danger of inflow of natural gas from neighboring wells has become more apparent each year since it was found that oil and gas underlie the productive coal measures of Pennsylvania, West Virginia, Ohio, Indiana, Illinois, Kansas, Oklahoma, Colorado, and Wyoming, and, to some extent, the coal measures of other States. The proximity of the known gas and oil areas in the United States to the coal fields and the manner in which the fields overlap in certain States are shown in the map comprising the frontispiece (Pl. I). As the result of many requests received from various sources a conference to consider the protective measures necessary to insure the safety of mining operations in gas and oil fields was called by the Director of the Bureau of Mines to assemble in Pittsburgh, Pa., Feb- ruary 7 and 8, 1913. To this conference were invited a considerable number of gas-well, oil-well, and coal-mine operators within conven- ient distance from Pittsburgh, as well as State geologists and State mine inspectors from a distance. Gas and oil wells are also found near other kinds of mines, such as shale and limestone mines in western Pennsylvania, but these cases are so few that for this and other reasons it was deemed best to con- fine the present inquiry to the consideration of the questions involved in connection with coal mines. It was also not thought advisable to consider the protection of mines from other kinds of bore holes than those for gas and oil, such as coal-prospecting holes, drilled either with churn or diamond drills, or salt wells and artesian wells, because little trouble has been ex- perienced in mining operations from these classes of wells. There- fore the following papers and discussions concern almost entirely the following relations between coal mines and gas and oil wells: (1) Protection of coal mines froin gas and oil wells penetrating -through: (a) Open workings; (b) inaccessible spaces or goaves; (c) pillars, or coal which may be left as pillars. (2) The manner of drilling gas and oil wells passing through workable coal beds so as to provide protection for future mining. The preliminary inquiries of the engineers of the bureau had dis- closed that there was no uniformity in the methods of protecting mines against the leakage of gas from wells, that thousands of wells in coal fields are abandoned yearly without adequate plugging, and without surveys or records being kept to show the location of the holes, from which the casings are generally pulled. According to the State geologist of Pennsylvania, as many as 3,000 wells are being drilled annually in Pennsylvania, 2,000 of these holes being aban- doned within a single year. It is such unplugged, uncharted wells that are the greatest menace in mining. The quantity of gas that the wells produce, although not sufficient to be commercially avail-

Jan 1, 1913

By J. L. Foster, G. R. Gray, T. S. Chapman

The wall-building properties of salt-water drilling muds can be improved markedly by the addition of: (I) natural gums, such as traga-canth, karaya, and ghatti; (2) seaweeds, such as Irish moss; or (3) gelatinized starch. Results of laboratory tests have been confirmed by field trials. For drilling operations in which the mud becomes contaminated by salt, either through penetrating salt-bearing rocks or by addition of sea water to the mud, the added cost resulting from the use of one of the substances listed above is more than offset by freedom from stuck drill pipe and ease in running casing. Introduction It has been recognized for many years that oil production might be seriously hampered by infiltration of water from the drilling mud.l-4 As knowledge of the mechanism of the wall-building process advanced, methods were developed for evaluating the filtration characteristics of muds.5-ll The wall-building properties of freshwater muds are commonly regulated by the addition of bentonitic clays, or of agents to promote the dispersion of the natural mud solids. When strata bearing soluble salts are encountered in the course of drilling, the salts are incorporated in the mud; the clay solids are flocculated and water loss is increased tremendously. Methods gen-crally used in controlling filtration of freshwater muds are no longer applicable. The problem of reducing water loss from salt-water muds is not confined to any particular area, but is acute in parts of West Texas. Salt beds several hundred feet thick must be penetrated before the oil-bearing formation is reached. Since the formation drilled does not provide mud-making material, it is necessary to use large quantities of commercial clays, and even the best commercial clay does not afford relief from the problem of high filtration. A laboratory study has been made of methods of improving the filtration characteristics of salt-water muds, and some of the methods have been used in field practice. Laboratory Investigations Procedure Inasmuch as the immediate object of the investigation was the development of means of improving the wall-building properties of muds used in West Texas, an attempt was made to employ muds in the laboratory study comparable to those in field use. Samples of muds used in drilling the producing formations in six wells were secured. The properties of these samples are summarized in Table I, which lists the densities, viscosities, filtrations, and analyses of the filtrates for calcium, chloride, and sulphate. Viscosity was measured in the Stormer viscosimeter at 600 r.p.m. Water loss was determined at 80°F. with the Baroid low-pressure wall-building tester8 at a pressure of 100 lb. per sq. in. Filtration rates are considerably higher than those of usual fresh-water muds, which amount to about 20 C.C. in 30 min. Water loss was so rapid in samples 4, 5 and 6 that filtration was complete in less than 10 min. and the values for 30 min. were extrapolated from the rates at shorter

Jan 1, 1942

By G. R. Gray, T. S. Chapman, J. L. Foster

The wall-building properties of salt-water drilling muds can be improved markedly by the addition of: (I) natural gums, such as traga-canth, karaya, and ghatti; (2) seaweeds, such as Irish moss; or (3) gelatinized starch. Results of laboratory tests have been confirmed by field trials. For drilling operations in which the mud becomes contaminated by salt, either through penetrating salt-bearing rocks or by addition of sea water to the mud, the added cost resulting from the use of one of the substances listed above is more than offset by freedom from stuck drill pipe and ease in running casing. Introduction It has been recognized for many years that oil production might be seriously hampered by infiltration of water from the drilling mud.l-4 As knowledge of the mechanism of the wall-building process advanced, methods were developed for evaluating the filtration characteristics of muds.5-ll The wall-building properties of freshwater muds are commonly regulated by the addition of bentonitic clays, or of agents to promote the dispersion of the natural mud solids. When strata bearing soluble salts are encountered in the course of drilling, the salts are incorporated in the mud; the clay solids are flocculated and water loss is increased tremendously. Methods gen-crally used in controlling filtration of freshwater muds are no longer applicable. The problem of reducing water loss from salt-water muds is not confined to any particular area, but is acute in parts of West Texas. Salt beds several hundred feet thick must be penetrated before the oil-bearing formation is reached. Since the formation drilled does not provide mud-making material, it is necessary to use large quantities of commercial clays, and even the best commercial clay does not afford relief from the problem of high filtration. A laboratory study has been made of methods of improving the filtration characteristics of salt-water muds, and some of the methods have been used in field practice. Laboratory Investigations Procedure Inasmuch as the immediate object of the investigation was the development of means of improving the wall-building properties of muds used in West Texas, an attempt was made to employ muds in the laboratory study comparable to those in field use. Samples of muds used in drilling the producing formations in six wells were secured. The properties of these samples are summarized in Table I, which lists the densities, viscosities, filtrations, and analyses of the filtrates for calcium, chloride, and sulphate. Viscosity was measured in the Stormer viscosimeter at 600 r.p.m. Water loss was determined at 80°F. with the Baroid low-pressure wall-building tester8 at a pressure of 100 lb. per sq. in. Filtration rates are considerably higher than those of usual fresh-water muds, which amount to about 20 C.C. in 30 min. Water loss was so rapid in samples 4, 5 and 6 that filtration was complete in less than 10 min. and the values for 30 min. were extrapolated from the rates at shorter

Jan 1, 1942

By Homer W. Riley

ANTHRACITE SMALL power-driven, toothed, cast-iron rolls were used first to break anthracite in 1844. Prior to that time, men with hammers, who stood on perforated cast-iron plates, broke the large lumps into commercial sizes. In order to convert run-of-mine into the various sizes required by the anthracite industry, about 20 million tons must be broken, annually, into smaller sizes. This phase of anthracite preparation is of major importance, because the degradation accompanying reduction in coal sizes should be kept at a minimum. The exclusive use of toothed rolls for that purpose indicates that comminution by rolls is the best solution of the problem. Many improvements have been made in tooth design, but the most important was a reduction of the peripheral speed of the rolls from 1000 to 300 ft. per minute. The higher speed was based upon and approximated the velocity of a falling piece of coal when it entered the rolls, Exhaustive roll tests at the slower speed showed that the same size reduction could be affected with less degradation. The adoption, therefore, of slow-speed, compound geared rolls, especially for breaking the larger sizes, became quite general after 1912. A high-speed roll is shown in Fig. 1 and a slow-speed roll in Fig. 2. Anthracite Crushing Problems.-Crushing anthracite presents the problem of selecting a series of rolls that will produce the greatest percentage of the prepared sizes of nut and over. The size distributions to be expected are shown in Table 1. Coal breaking and crushing practices in anthracite breakers involve the use of equipment for comminuting the following classes of material: 1. Run-of-mine-plus 6 ½ -in. coal. 2. Sized coal-steamboat, broken, egg, stove, nut, and pea. 3. Flat coal--coal that is flat and hence not suitable for the market. 4. Bone--a piece of laminated coal and slate, crushed for the purpose of reclaiming the coal. 5. Breaker refuse, reduced to a size suitable for flushing into a mine for back-filling purposes.

Jan 1, 1950

By Roswell P. Angier, Herbert S. Kalish, Henry H. Hausner

POWDER metallurgical methods as applied to zirconium are of great interest because they permit not only the fabrication of parts directly to shape with a minimum loss of material but also the utilization of scrap, and the metal may be processed at temperatures well below the melting point. There are two difficulties involved in the melting of zirconium: 1—High vacuum is necessary for melting, and 2—zirconium reduces nearly all oxides so that it is difficult to find a suitable crucible material. The purest material, zirconium crystal bar, is expensive, and the methods of subsequent fabrication are limited. Cold rolling or extrusion of zirconium crystal bar is suitable for making certain shaped parts, but where melting is involved, the purity of the metal is invariably decreased, and a method of casting to a definite shape does not seem to be feasible. Where it is necessary to hot roll, zirconium must be covered with a steel or copper jacket to protect it from the air. This is necessarily a costly operation. Where annealing of zirconium is necessary it must be conducted in a high vacuum. In an investigation of powder metallurgical methods for zirconium, the zirconium powder used should be characterized by the following properties: 1— Highest degree of purity, 2—uniformity in particle shape and particle size distribution, 3—low compression ratio, and 4—satisfactory strength of the compacted powder (green strength). Zirconium powders have been made by two methods: By the reduction of zirconium tetrachloride (ZrC1,) with sodium,2' *•B "nd by the reduction of zirconium oxide with calcium and calcium chloride." The first method represents one of the earliest attempts to make pure zirconium metal, and the sintered product from this powder is extremely brittle. The second method of making zirconium powder is far more successful, but the powder made in this way has an extremely low apparent density and, therefore, a high compression ratio which makes it difficult to use it for powder metallurgical purposes. For these reasons the above-mentioned zirconium powders were not used in this investigation. To obtain sintered zirconium compacts of highest 'purity and good ductility, it was first necessary to produce a suitable powder. Pure zirconium has been made chiefly by two methods. The iodide method, from which the product is "crystal bar" zirconium, was developed first.'." By this purification process very soft, pure, and ductile zirconium metal can be produced. The second method, developed by the U. S. Bureau of Mines, is the reduction of zirconium chloride with magnesium." The sponge zirconium thus produced is also soft, pure, and ductile.

Jan 1, 1952

By Roy Norcross, Stephen Gos

For over 100 years Degussa has worked together with the min­ing industry not only providing quality products but also develop­ing technologies to support these products through value added goods and services. For cyanide, these technologies include leach enhancement processes such as PAL™ and Solidox™, and cyanide detoxification with peroxygen based processes such as SILOX™ and Caro's acid using our DegOX™ technology. Degussa has also made important advances in how sodium cyanide is packaged and shipped with our liquid NaCN plant joint venture with MSI, CYANCO in Winnemucca, Nevada, and our Advantage SLS™ solid to liquid cyanide delivery system. All of these innovative technologies developed to support NaCN in mining, provide value to our customers and show Degussa's commitment to Responsible Care·11.1 and dedication to product stewardship. With Responsible Care and the customer in mind, Degussa has developed Advantage CCS™ cyanide control system, which will soon be available for the North American market. Currently there are several CCS units in service installed by Degussa AG (Germany), and we are in the process of designing the next gen­eration of the CCS which should be completed by late '98. Based on our experience working with gold and silver mines all over the world, there appeared to be an opportunity to further assist our customers by providing a better more automated way to control their cyanide additions. By providing the mine with an accurate method for maintaining their desired cyanide levels in their leach circuits, we could help them avoid underdosing and the associated gold and silver losses, and overdosing the cyanide which not only wastes cyanide but may increase treatment costs as well. In the early 1990's, when we began to introduce our CCS units, there were several cyanide controllers and on-line analyzers avail­able. However, they appeared to be too complicated and not made to stand the harsh conditions inside a mill. This resulted in exces­sive downtime and poor analytical results. We also found that many units would be installed but not commissioned by the sup­plier. Based on these observations, along with filtration and con­trol problems on some existing units, Degussa decided to design its own cyanide control system based on our extensive knowledge of cyanide chemistry, using the best components available worldwide.

Jan 1, 1998

By W. Choi

The present study revealed that the bioleachability of a chalcopyrite flotation concentrate is influenced by the semiconductor properties of CuFeS2. The overall reaction of biooxidation,

Jan 1, 1991

By H. M. Chance

(Butte Meeting, August, 1913.) ADEQUATE treatment of the difficulties surrounding the valuation of mineral lands requires that agreement be first reached defining value as understood for the purpose of appraisal. To define value as the price of a product is not sufficient, and does not assist us in using the factors that cause variations in values and in relative values. The real value of any product depends primarily upon its relation to the necessities, comforts and pleasures of mankind. As the necessities, comforts and pleasures of the civilized races differ-from those of more primitive man, the value of products varies with the degree of civilization and the environment of the consumer. Coal has no value to the savages of warm climates, and arrow-head flint none to the residents of New York. It has long been recognized that what has. been termed ?intrinsic value " must be limited to materials that are essential to existence-air, water, food. But " intrinsic value " cannot be measured in monetary terms. The intrinsic value of a bushel of wheat is due to the fact that it will support the life of an individual for a certain definite time, but this fact does not enable us to measure or to express that value in monetary terms. It has often been proposed to adopt as a measure of the value of any product the quantity of labor necessary to produce it, but this method is of limited application, and will not apply to what may be termed " intrinsic values." For many reasons it might be well, while assenting to the fact that any material may be intrinsically valuable, to abandon the use of the term "intrinsic value." One of these reasons is the tendency to confuse the idea of " intrinsic value with a value that is conferred by economic conditions, that is purely artificial and that may be permanent or evanescent. Intrinsic value must from its nature be permanent and unchangeable.

Jan 7, 1913

By Henry D. Hibbard

The finishing and casting temperature of steel is a subject concerning which there is so much to learn that some temerity is required to write about it. This paper is, therefore, suggestive rather than dogmatic, though the views expressed seem now to the writer to be correct; nevertheless, they may be modified by future developments or discoveries but until then may be of some utility, particularly to beginners in the making of steel. Consideration is limited to the temperatures of simple steels, also called carbon steels, which are those in which carbon is the only element introduced for the purpose of conferring desired physical properties. Alloy steels will receive attention later. Three things largely determine what a batch of steel really will be; via., composition, casting temperature, and rate of teeming. Each has its advocates as being the most important; but they are so interrelated that each must conform to or be right for the other two. When one is claimed to be the most essential to have right, that, probably, was the one that it was found had to be of a certain description, within narrow limits, to suit the already adopted variations of the other two; that is, it was the last of the three to be brought into line. The term "casting temperature" is rather indefinite as there ale several temperatures to which the term may be applied. Most writers who have mentioned casting temperature of steel have alluded to it in relative terms. The few who have given actual temperatures, including Langmuir, Burgess, Styri, and Bash, do not give full information about them. Their results demonstrate the efficiency of pyrometers used rather than aid the steelmaker. In order to understand and use the temperatures, one should know in each case what the steel was, the stage at which the temperature was taken, whether it was usual or not, and whether or not it was right for that steel at that stage. When these

Jan 1, 1925

By Herbert H. Kellogg

Graphs representing the standard free-energy of formation as a function of temperature for 21 fluorides are presented, along with estimated values for the standard free-energy of formation of 20 atedadditional fluorides. A few of the many possible uses of these data in metallurgical calculations are discussed, including the fluorination of oxides, sulphides, metallurgicaland chlorides, and the reduction of metal fluorides. RECENT papers which have presented free-energy data for oxides, sulphides, chlorides, carbonates, sulphates, and silicates in the form of free energy vs. temperature plots,1-5 have found important uses in teaching and metallurgical development work. This method of presentation of thermo-dynamic data serves to make available in readily usable form thermodynamic constants which are scattered throughout the literature, and to show by graphical means the stability relations which exist between the compounds of a given type. It is certainly desirable to have these free-energy-temperature diagrams for as many types of compounds as are of present or potential use in metallurgical processes. Thus, even though there are but few uses of metallic fluorides in extractive metallurgy today, the potential uses of fluorine processes are of great importance and serve as the principal justification of this paper. Recent developments in the production of fluoro-carbons have resulted in vastly improved methods for the production and handling of fluorine and corrosive fluorides, with consequent reduction in costs.".' The extractive metallurgist should no longer overlook possible fluorine processes when development of a new process for a relatively high unit-price metal is being considered. In a previous paperv he author outlined in some detail the importance and use of free-energy data in metallurgical calculations and also discussed the properties of a standard free-energy vs. temperature diagram. The same method of presentation is adopted in this paper, and the reader is referred to the earlier work for explanations of the use of free-energy data. Thermodynamic Data This paper presents standard free-energy vs. temperature diagrams, Figs. 1 and 2, for those fluorides for which the major thermodynamic constants are known. In the calculations of the standard free-energy of formation (AGO), values of the enthalpy of formation at 298°K (?Ho,) were taken from "Selected Values of Thermodynamic Constants"8 most of the values of standard entropy at 298°K (S°298) were taken from "Selected Values"," but in a few cases the values given by Kelley9 ere preferred; data for the Phase changes came from "selected Values" and several of Kellley's publics- tions;0-12 and most of the specific-heat data were taken from Kelley.l0 The appendix gives a detailed list of the sources of the data. As explained in an earlier paper,6 he accuracy of some of the standard free-energy relationships is not high. An error of +1 kcal at 1000°C is expected in most of the curves of Figs. 1 and 2. The error may be as high as +3 kcal in some of the curves. Rather than attempt to estimate the reliability of each curve, the source of the data used is reported in the appendix, and the reader may compare these data with newer values as they become available. Figs. 1 and 2 fail to show values for the fluorides of many important metals. In most cases this is because the entropy of the metallic fluoride is unknown. For preliminary calculations it is often useful to have available the best estimate of an unknown datum, rather than no information at all. With this in mind, Table I lists estimated standard free-energy values for a number of important metallic fluorides not included in Figs. 1 and 2. The values reported in Table I were, calculated by Brewer et al.13 and are based on estimated entropy values. The estimated uncertainty of the values for each fluoride were calculated from the uncertainty values given by Brewer1' for ?H°, and the entropy function.

Jan 1, 1952

By N. P. Hristov, L. V. Kuzev

"A simulation study of the fill factor of a drum mill was conducted using two types of grinding media: balls and tetraballpebs. Each medium was composed of equal number of grinding bodies having equal weight but different shape. The difference was in the density of the two grinding media.Standard spherical grinding bodies (balls), which were used in practice, and equivalent (by weight) grinding bodies in the shape of spheroidal tetrahedrons (tetraballpebs) were studied. The simulation was conducted in a module of a 1.2 m diameter drum mill, whose length exceeded twice the diameter of the corresponding grinding body. The grinding balls had a few percent (3 to 6) higher fill factor than the grinding tetraballpebs in the same shell.Vertical sections of the grinding medium were taken across the studied shell module along its axis. They showed the location of each grinding body in the fill volume. Defects in the packing of the grinding bodies and the contacts between them and with the inner surface of the shell were also show. Differences in the contact points of the balls and the tetraballpebs were noted. For the tetraballpebs, we observed contacts both between the spherical surfaces and with the edges and vertices of the grinding bodies.The topography of the grinding media is shown visually.INTRODUCTIONThe grinding balls have been studied extensively. It is the traditional grinding medium in ore processing industry. The parameter characterising the grinding medium is its density. It is the mass of the grinding medium per unit of volume. The parameter may have a range of values. It depends on:• The physical properties of the material they are made of;• The shape of the grinding body;• The dimensions of the body;• Size distribution of the grinding bodies in the grinding media.In comminution, the fill factor of the mill shell is the process parameter that is representative of the grinding medium. Some publications have indicated the disadvantages of ball grinding. For example, Wu, Xiang, Glen, and Duan (2008) note in the analysis of the mechanism of grinding that the balls are not the best grinding media and disadvantages include among others:• Easy over-grinding resulting from the point contact between the balls;• Attrition surface is the smallest in the grinding media;• Poor selective exposure of minerals resulting from the accidental and often significantly more powerful impact on the feed;• The grinding efficiency drops as the fineness of grind is increased;In the Handbook of mineral processing, Polkin (1950) noted that the shape of the grinding bodies determines the volume of the void spaces therein and therefore the shape affects the grinding efficiency per unit of volume of the grinding medium."

Jan 1, 2016

By Arthur Green

A GROUP of 13 cities situated in Los Angeles and Orange counties in Southern California is engaged in constructing an aqueduct to carry water from the Colorado River at a point near Parker, Arizona, to a distribution point sear Riverside, California. The aqueduct will have a total length of approximately 241 miles, and is designed to deliver 1605 cu. ft. of water per second, or a little more than one billion gallons per day. The aqueduct crosses a barren, desert waste and the project includes approximately 91 miles of 16-ft. tunnel. The large amount of tunnel driving that has been done in this country in the past few years has resulted in some remarkable developments in equipment and methods. The building of the Colorado River Aqueduct, with its 91 miles of tunnels, has called on the best engineering knowledge in the country. New and better equipment has been designed for all phases of the work, and this equipment has been coordinated and adapted to the various conditions with a high degree of efficiency. The result has been that records for tunnel driving have been set under adverse natural conditions that exceed the estimates for progress under good conditions. All of the tunnels in the main aqueduct, except the Valverde and Bernasconi at the western end, have a finished diameter, inside the concrete lining, of 16 ft. Fig. 4 shows a section of the tunnel with the concrete lining in place. Fig. 5 illustrates the finished tunnel in three typical sections. The standard tunnel grade is 3.432 ft. per mile in the 16-ft. tunnels, but the Valverde and Bernasconi tunnels have a steeper grade and a finished diameter of 15 ft. 3 in. The rough bore of the large main aqueduct tunnels averages 12.95 solid cubic yards of material per foot of advance in timbered sections and 10.76 solid cubic yards per foot in unsupported sections.

Jan 1, 1936

Before presentIng my address I wish to acknowledge the honour which has been conferred on me by my appointment to the position of President of the Australasian Institute of Mining and Metallurgy.It is a matter of great concern to us all to find our Empire at war. I am confident that, as was the case in the war of 1914-1918, members of this Institute and of kindred Institutes and Associations will contribute in full to the Empire's needs and that in the end our cause shall triumph.I think it appropriate that I should take as the subject of my address that of the Broken Hill Lead-Silver-Zinc Industry. The subject matter of this address has been confined to the operations of Mining, Ore Dressing, Lead Smelting and Refining and production of Electrolytic Zinc in Australasia. The review of the Broken Hill Lead-SilverZinc Industry would not, of course, be complete without reference to those Australian industries which trace their origin to the Broken Hill field, but· it is thought that an outline of these industries would make thIs review too extensive.HISTORICALMany efforts have been made to translate the early history of Broken Hill and its subsequent growth throughout the years into one of the wor~d's most famous mining fields in the form of a simple story.

Jan 1, 1940