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IT may perhaps seem to you that I have deviated from sequence by having entered into the narration of this arrangement of the bellows, but, although they are not furnaces or vessels for containing the melts, they are essential agents for bringing to port the bark of your labors. Returning to our regular pathway, and supposing that, besides making the moulds, you have melted and cast not only statues and bells but also guns, it is true that a certain procedure is required in order to finish them. For this you should have the moulds full, and they should have come out very well, for in truth reason does not allow that they turn out otherwise for one who uses precaution. [II2V] Then you have taken your casting from the pit and have freed it of clay. Since I have told you nothing beyond this, do not be dismayed if you see the castings so rough and in a form that scarcely shows what they really are, for I wish to open up part of the way into the great labor of finishing them so that it may seem to you that you have been somewhat helped by me. Therefore, when it is a gun, first see that the iron spindle that has been placed in the middle of the core is taken out. You can do this easily by striking the heel of the core, especially if the spindle had first been covered with ashes, hemp, or a little rope. Then saw off the feeding head above the mouth, using either a dun steel saw with tiny straight teeth that has been tempered with oil or some other fat, or a hay sickle whose edge is gently hit by a little hammer. Then have the clay that is attached to the curls or other bronze parts lifted away with a chisel. Then with a scouring brush and water uncover the emblems, coats of arms, borders, and cornices that you made as ornaments. Striking it with a hammer, push inwards every superfluous bit of bronze. Finally, having cleaned the bronze by washing, scraping, and cutting away every bit of clay, strike its surfaces gently with a large hammer and thus make it very smooth. Likewise finish the mouth and all its cornices as exactly and completely as possible with files and any other instrument that serves best. Then take a long, powerful tool that has some steel on the point, made like a chisel and somewhat bent, or with three points like the iron blade

Jan 1, 1942

Jan 1, 1924

By Philip J. Shenon

IN 1947 the mining industry strove desperately to regain operating normalcy. During the first part of the year the industry in this country was plagued with labor shortages, strikes, and portal-to-portal lawsuits. Then followed the uncertainty of Government policy with respect to subsidies and tariffs; and the long and bitter controversy as to whether we are a nation of mineral "haves" or "have-nots." As the year progressed the labor supply impoved somewhat and the Taft-Hartley law brought partial relief to strike-troubled industry. The uncertainty with respect to tariffs was partly answered by President Truman on April 29 when he announced the suspension of the 4¢ import duty on copper until March 31, 1949, and later, near the close of the year, by the announcement of the tariff agreement signed by the United Nations at Geneva. By this agreement tariff rates are to be adjusted downward, or "bound" at their present levels, for three years, on commodities amounting to some 60 per cent of United States trade. Effective Jan. 1, 1948 the rate of duty will be substantially reduced on ores, concentrates, or metals of zinc, aluminum, copper, manganese, tungsten, iron, steel, barytes, nickel, cadmium, and antimony.

Jan 1, 1948

By R. W. Culbertson, S. Kasper

During the 1920's, approximately 11,000 small gasifiers were in operation in the United States. They converted about 15 million tons (13.6 Mt) of coal per year into low Btu gas. In some cases, hot raw gas was used for applications such as firing open hearth furnaces or brick kilns. In other cases the gases produced in the gasifiers were cooled, cleaned and desulfurized for various utility and industrial purposes. The steel industry was by far the largest user. The most important fact was that the conversion of coal to a usable fuel gas was demonstrated to be commercial. During the late 1940's and early 1950's, this form of energy was largely replaced by natural gas as the pipeline net work was expanded. Producer gas was no longer economically competitive. Over the past 25 years, government controls on the interstate price of natural gas have maintained this situation. At present only three commercial small coal gasifier plants are still in operation in the United States. These facilities are operated

Jan 1, 1980

By AIME AIME

IF the observation of our British friends is true that Americans put new records in bigness above everything else then the 150th meeting of the Institute was not the grand success it seemed to be. Just why the attendance slumped a little this year is anyone's guess, but the favourite explanation seemed to be that half the country is planning to come to the New York World's Fair this summer and that two trips from the hinterland to the me- tropolis, with another to San Francisco of course, can hardly be justified with the present condition of the stock market and the prices of the products of our mines. Certainly, some were pre- vented from coming too by the epidemic of respiratory afflictions that was rampant in February. Unfortunately. several succumbed after they had reached New York.

Jan 1, 1939

By Charles D. Borror, George K. Foster

The Jeffrey mine of the Canadian Johns-Manville Co., Limited, is in the town of Asbestos, situated approximately 100 miles northeast of Montreal and about the same distance southwest of Quebec, in Richmond County, Quebec. Mining operations were started in 1881 on outcrops on a hill, as a side-hill cut, followed by a second and third cut. This development was the forerunner of the present large open-pit operations, the mine now ranking as the largest open-pit asbestos mine in the world. Operations were first carried on by hand, then by horsepower and later by stem cableways. By 1924 the derrick spans, 2000 ft. or more long, became unwieldy. To overcome this, and also to eliminate hand labor as much as possible, steam shovels and railroad haulage were introduced. The steam shovels were replaced in 1928 by larger electric shovels of the full-revolving type. The Ore Body The ore body is a serpentinized peri-dotite rock mass. The chrysotile fibers form a network of veins throughout, varying from microscopic width to two or more inches measured across the veins (Fig. I). These veins may be continuous for a few or many feet; they may increase or decrease in width within a few feet. The veins in which the fibers occur per- pendicular to the veins are known as cross fiber. Those in which the fibers lay parallel to the veins are known as slip fiber. The cross fibers are of better quality, and more in demand. The majority of the fiber

Jan 1, 1948

By George K. Foster, Charles D. Borror

The Jeffrey mine of the Canadian Johns-Manville Co., Limited, is in the town of Asbestos, situated approximately 100 miles northeast of Montreal and about the same distance southwest of Quebec, in Richmond County, Quebec. Mining operations were started in 1881 on outcrops on a hill, as a side-hill cut, followed by a second and third cut. This development was the forerunner of the present large open-pit operations, the mine now ranking as the largest open-pit asbestos mine in the world. Operations were first carried on by hand, then by horsepower and later by stem cableways. By 1924 the derrick spans, 2000 ft. or more long, became unwieldy. To overcome this, and also to eliminate hand labor as much as possible, steam shovels and railroad haulage were introduced. The steam shovels were replaced in 1928 by larger electric shovels of the full-revolving type. The Ore Body The ore body is a serpentinized peri-dotite rock mass. The chrysotile fibers form a network of veins throughout, varying from microscopic width to two or more inches measured across the veins (Fig. I). These veins may be continuous for a few or many feet; they may increase or decrease in width within a few feet. The veins in which the fibers occur per- pendicular to the veins are known as cross fiber. Those in which the fibers lay parallel to the veins are known as slip fiber. The cross fibers are of better quality, and more in demand. The majority of the fiber

Jan 1, 1948

By R. R. McNaughton

The Consolidated Mining and Smelting Company of Canada, Ltd. at Trail, B. C., inaugurated a comprehensive program of investigation about 15 years ago to develop the most economical process of recovering the metal in the large accumulated stock of by-products of the lead smelter and the zinc plant. Two principal methods of recovery were followed to a successful conclusion—an electrothermic process to treat zinc-plant residues and cold slag and the fuming of hot slag from the lead blast furnaces. The latter was selected because it showed a saving over the former in its ability to handle hot blast-furnace slag, thus obviating the necessity of granulating, handling and eventually remelting the same slag for the electrothermic process. The design of a fuming plant was commenced in 1928, and construction, which was started immediately, was completed in July 1030. Operating intermittently for a general tuning up, the plant was officially blown in for regular operation in August. During this month the vagaries of a slag-fuming plant were studied and an operating crew was trained. A history of slag fuming at Trail and the development of plant design is given in a paper by G. E. Murray in the Transactions of the Canadian Institute of Mining and Metallurgy for 1933. Fuming Plant The fuming plant at Trail (Fig. 1) is a separate unit although of necessity interlocked closely with the lead smelter. The plant consists essentially of a fuming furnace with its accessories, a waste-heat boiler followed by an economizer, and a suction-type baghouse. The plant was built as the first of two 400-ton units with the intention of adding the second unit within a year, so that flues, fans and buildings were built to handle double the original load. Furnace.—The furnace as originally built (Fig. 2) was of water-jacket construction, 10 ft. wide, 20 ft. long and 6 to 10 ft. high. The roof height was made variable to check experimental work, which had indicated that this dimension affected the rate of reduction. Coal and air were supplied

Jan 1, 1937

[NORTH AMERICA ALASKA Anchorage.-Strandberg, H. Chlchagoff.-Russell, J. C. College.-Barber. R. J. Dorsh, J. B. Fox, E. F. Joesting, H. R. McAnerney, J., M. Douglas.-Cahill, W. E. Fairbanks.-Beistline, E. H. Crawford, J. D. Earling, R. B. Greves, J. H. Harris, Q. P., Jr. Henton, H. M. Herbert, C. F. Hester. W. B. Hopkins, J. E. Kreitlow, E. J. MacDonald, D., III March, J. P. Mathews, T. C.]

Jan 1, 1940

By Ross W. Smith, Nikhil Trivedi

The variation of point of zero charge (PZC) of both simple and complex oxide minerals was studied as a function of aging time in water. In most cases the PZC's of the simple oxides moved toward more basic pH values with aging time. Evidence to date suggests that this phenomenon relates to dissolution of disturbed layers on the mineral's surface accompanied by later readsorption of metal hydroxy species back onto these surfaces. The readsorption takes place after the solution becomes supersaturated with respect to some crystalline phase. The variation of PZC's of complex oxides as a function of aging time in water is apparently related to several different mechanisms. In a few cases PZC shifted toward more basic values with time. This shift could be attributed to much the same mechanism as for simple oxides. In most cases, however, PZC of complex oxides shifted toward more acid values with aging time, probably because of loss to solution of soluble cations whose oxides possess basic PZC's.

Jan 1, 1975

Jan 1, 1929

By Michael A. Devane, Neil Duncan

Inclines and tunnels can extend from ground surface to considerable depths traversing a wide range of lithologies. The strata encountered may be affected by loosening and induced stresses at different locations along the route. It is suggested that Phase I of the pre- driving assessment process should include study of the geology, hydrogeology, rock material and rock mass characteristics. A rock mass disruption factor is used to express the ratio of the unconfined strength of intact rock material to the unconfined strength of in situ rock mass. It is suggested that there is a relationship between in situ (secondary) permeability values and the disruption factor, since the permeability of the rock mass is governed by parameters which influence strength. In Phase I1 of the pre-driving assessment, consideration should be given to the prediction of primary loosening which results largely from disturbances to the rock mass arising from the driving process. Also in Phase 11, preliminary assessments are made of the effects of induced stresses and of the geodurability characteristics of the rocks. In Phase 111, the mechanics of various secondary loosening pro- cesses are considered along with their relevance to estimates of stand up time and support requirements. Yield-line analysis is introduced for the study of plastic and brittle type bending deformations. Stand up time and support characteristics are also assessed. In Phase IV, the effects of induced stresses are analysed. It is suggested that even for broken rock in the Yield Zone, the rock mass disruption factor may not often increase above lo which is equivalent to an in situ permeability of 10-1 m/s.

Jan 1, 1983

By Edwin B. Wilson, Charles F. Cockrell

The application of evolutionary operation is proposed for the cleaning of coal by the heavy media process. Analysis of the data given suggests some benefits that may not be immediately appreciated unless evolutionary operation is applied. For example, while it may seem obvious to increase specific gravity when the ash and sulfur content of the clean coal is lower than that allowed, evolutionary operation may show that an increase in feed rate or an increase in both feed rate and specific gravity would be a more profitable alternative. In addition, by using evolutionary operation, up-to-date knowledge of the effect of change of feed rate or specific gravity on yield and product quality is available. This information facilitates confidence about decisions made in regard to the day-to-day operation of these units. A number of other applications in the minerals industry are proposed. An application of evolutionary operation in a related field is also given where a large number of variables were required to be optimized.

Jan 1, 1969

By Paul D. Merica, O. B. J. Fraser

PROBABLY the first metallic objects used by man were nickel alloys. In search for flints suitable for the fashioning of their rude tools, our paleolithic ancestors, some 25,000 years ago, quite likely may have come upon some of those heavy, metallic fragments that we now know as meteorites, which consist of an alloy of nickel and iron containing usually from 5 to 15 pct of nickel. Whether paleolithic man ever did discover and use meteoritic fragments, his sketchy records do not actually disclose. We do know, however, that such fragments have been found and used by peoples, particularly the North American Eskimos, for weapons and implements in just the same manner as stones, and prior to any knowledge by those peoples of the reduction of metals from ores. Meteoritic showers were recorded frequently in earliest times and the meteorites often were found and fashioned into useful objects. The ancient Arabic and other myths of "invincible swords fallen from heaven" seem thus to have had a very definite basis in fact, and such weapons, of meteoritic material, have actually been re- covered from archeological excavations. It thus seems probable that meteoric nickel-iron was found and used long before iron was recovered by smelting iron ores (perhaps about 1200 B.C.) and probably even before there was knowledge and use of bronze and gold. Although many centuries were to pass before nickel was first isolated, in 1751, from Swedish ores and recognized as an elemental

Jan 1, 1953

By Charles B. Dudley

DEAR SIR: It is now nearly three years since my first report to you on the subject of steel rails was written. That report, as you will remember, dealt principally with the question of the relation between the chemical composition and physical properties of steel rails end their power to resist crushing and fracture in actual service. Other matters were referred to or touched upon in that report, but the main question was, Why do some rails crush or break in service while others do not? Yon will doubtless remember that the principal conclusion arrived at was, that the softer rails are less liable to Crush or break in service than the hard ones. Or, in other words, so far as conclusions could be drawn from the chemical analysis and physical test of 25 samples of steel rails which had actually been in service, these conclusions were that those rails which have the smaller amounts of carbon, phosphorus, silicon, and manganese are less liable to crush or break in service than those which have larger amounts of these elements. Or, again, looked at in the light

Jan 1, 1881

By A. L. Holmes

Significant technologic advances were made in open pit mining during 1973. The industry faced mounting problems on one front where expansion of stripping activities encountered enlarged public resistance and on another where manpower and materials were in short supply. These challenges, along with the challenge and opportunity to meet the increased demand for mining products including materials for energy production, placed a premium on technical developments and their application. The demands on technology also included the providing of facilities and methods to economically extract minerals from deposits of lower grade, lesser accessibility, and where other uses of land approached the value of its minerals. Detection of Failures in Slope Walls The Bureau of Mines has undertaken research directed towards providing a mine operator with the opportunity to take corrective action before a potential slide becomes a problem.

Jan 2, 1974

By Louis J. Demer, Paul A. Beck

As reported in a previous publication,1 isothermal grain growth in high purity aluminum and in an aluminum alloy with 2 pct magnesium can be adequately described by means of the empirical relation: [ ] or in some cases, by the simpler relation, [ ] Here, D is the average grain size after an annealing period t. The annealing period includes the time for complete recrystallization R, and the time for grain growth [to]. DA is the grain size as recrystallized, n is a parameter depending on the temperature and on the material. The effect of 2 pct magnesium in solid solution was to decrease D, and to increase R, A and n at a given temperature. The present work was undertaken in order to investigate the above listed effects of magnesium in solid solution, as functions of the magnesium content. The work also includes the study of certain anomalous effects observed in the recrystallization and grain growth of the 2 pct magnesium alloy at 350°C. EXPERIMENTAL PROCEDURE The method of producing the ingots used in this work was described in detail1 and need not be reproduced here. The materials used were high purity aluminum, furnished by the Aluminum Co. of America, of lot analysis shown in Table I and magnesium from a high purity distilled stock of magnesium crystals. [ ] Ingots were prepared for a series of binary aluminum-magnesium alloys of increasing alloy content. The numbers used to designate these ingots and their magnesium contents by chemical analysis are given in Table 2. [ ] The analyses showed no difference in composition between the top and the bottom of the ingots. Spectrographic analysis of the ingots for elements other than magnesium showed, within the limits of accuracy of the method, no increase in impurities over the amounts given in the lot analysis for the high purity aluminum in Table I. Careful microscopic study of ingot 21 in the as-cast condition, at magnifications up t0 1500X, revealed a cer-

Jan 1, 1948

By Wilfred P. Sykes

AT intervals in the course of history an event occurs which, though scarcely heeded at the moment, marks in retrospect the beginning of a new era in some one field of human activity. Such a happening is perhaps more readily spotted in the field of technology than in other realms of human endeavor. Here the span of years is relatively short and the records have been kept with some degree of precision. In the current scene of our social and economic drama the art and science of metallurgy is playing a major role. Off stage will be found the metallurgist in one guise or another aiding, he trusts, in the development of processes and products which will contribute to the happiness of his fellow men. The results of his efforts appear in the form of metallic substances known as alloys built up from any two or more of the wide variety of metals which have been extracted from the mineral deposits in the earth's crust. An alloy by virtue of its inherent physical properties may seem ideally suited for human use in a special way but until this material can be produced economically it will fail to attain a place of prominence as an article of commerce. In fact many commercial alloys are being continually replaced by new or modified compositions better suited to meet the increasingly severe demands of industrial service.

Jan 1, 1939

By R. Ingerson

Bore surfaces of used guns commonly show a pattern of cracks in various degrees of development. It has been suggested that these cracks may aid erosion by providing channelways for the gases, eventually leading to the tearing out of blocks of metal. Under the general studies of gun erosion conducted at the Geophysical Laboratory it appeared desirable to consider this factor, and to determine the resistance to surface cracking offered by gun steel and by various other materials that might be used in the bores of guns. Method and Apparatus In order to make such a determination it is necessary to have (I) an arrangement in which the surface to be studied can be subjected to conditions similar to those in a gun with respect to temperature, pressure (developed by explosion gases), composition of the gases and length of time the surface is exposed to the gases; and (2) a specimen that can be examined readily after any number of shots, and then fired again, if necessary. The first of these conditions can be met by using an explosion vessel designed by H. S. Roberts of the Geophysical Laboratory. Fig I shows a cross-section of the apparatus. The "gun" G from which the charge is fired is made from the receiver of a caliber 0.30 army rifle, M1903, and the charges are prepared in caliber 0.30 cartridge cases. The test specimen S is held in place by a cone-shaped plug P and by a steel bridge B which is bolted to the outside of the explosion vessel on either side of the section shown. The plug, in turn, is held in place by a screw collar C. Maximum pressure is controlled by a brass rupture disk R. Part of the explosion gases flow past the two flat areas on S. Temperature and composition of gases, and the time before the rupture disk breaks, can be controlled by amount and kind of powder used, and pressure can be controlled by using rupture disks of different thickness. While the explosion vessel used was not designed so that temperature and pressure could be measured, in other vessels of closely similar size and shape containing proportionate charges of the same kind of powder as that used for standard testing procedure, values of 2700°K and 50,000 psi were obtained. Since the orifices past the flat areas on the plug are small compared to the rupture disk hole (I:I6), most of the gas goes out through the rupture disk when it breaks. The amount that goes by the plug depends on (I) the pressure attained before the rupture disk breaks and (2) the time it takes for this pressure to be built UP. The second condition (examination at will after any firing) is met by using for specimens short rods that have flat areas ground on opposite sides. These flat

Jan 1, 1949

By R. Ingerson

Bore surfaces of used guns commonly show a pattern of cracks in various degrees of development. It has been suggested that these cracks may aid erosion by providing channelways for the gases, eventually leading to the tearing out of blocks of metal. Under the general studies of gun erosion conducted at the Geophysical Laboratory it appeared desirable to consider this factor, and to determine the resistance to surface cracking offered by gun steel and by various other materials that might be used in the bores of guns. Method and Apparatus In order to make such a determination it is necessary to have (I) an arrangement in which the surface to be studied can be subjected to conditions similar to those in a gun with respect to temperature, pressure (developed by explosion gases), composition of the gases and length of time the surface is exposed to the gases; and (2) a specimen that can be examined readily after any number of shots, and then fired again, if necessary. The first of these conditions can be met by using an explosion vessel designed by H. S. Roberts of the Geophysical Laboratory. Fig I shows a cross-section of the apparatus. The "gun" G from which the charge is fired is made from the receiver of a caliber 0.30 army rifle, M1903, and the charges are prepared in caliber 0.30 cartridge cases. The test specimen S is held in place by a cone-shaped plug P and by a steel bridge B which is bolted to the outside of the explosion vessel on either side of the section shown. The plug, in turn, is held in place by a screw collar C. Maximum pressure is controlled by a brass rupture disk R. Part of the explosion gases flow past the two flat areas on S. Temperature and composition of gases, and the time before the rupture disk breaks, can be controlled by amount and kind of powder used, and pressure can be controlled by using rupture disks of different thickness. While the explosion vessel used was not designed so that temperature and pressure could be measured, in other vessels of closely similar size and shape containing proportionate charges of the same kind of powder as that used for standard testing procedure, values of 2700°K and 50,000 psi were obtained. Since the orifices past the flat areas on the plug are small compared to the rupture disk hole (I:I6), most of the gas goes out through the rupture disk when it breaks. The amount that goes by the plug depends on (I) the pressure attained before the rupture disk breaks and (2) the time it takes for this pressure to be built UP. The second condition (examination at will after any firing) is met by using for specimens short rods that have flat areas ground on opposite sides. These flat

Jan 1, 1949