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By J. C. Bayles

Jan 1, 1886

By A. U. Seybol

Eight binary iron alloys were examined after ion nitriding experiments to determine the behavior of the following elements: Al, Mo, Mn, Si, Ti, V,Cr, and C. Only Al, Cr, Ti, and V additions caused hardening in binary iron alloys. A few steels were examined to see the effect of Cr, Cr + Al, Cr + Ti, and Cr + V. It is suggested that a useful new class of ni-triding grade steels might be those containing about I pct V. The nitriding of steel, first described by Fry1 about 45 years ago, rapidly attained commercial application with very little knowledge of the fundamentals involved. While Fry,' in describing the status of nitriding in 1932, apparently correctly postulated hardening by precipitated nitrides, the details of the nitriding process were not understood, nor has the situation changed much since that time. It is also interesting to note that the compositions of some typical nitriding steels given by Fry at that time have changed little in the intervening years. Currently used nitriding steels owe their surface hardening to either chromium (as in 4340 steel) or aluminum plus chromium as in the Nitralloy grades, where both CrN and AlN appear to contribute to harden ing. Titanium additions have been studied experimentally, but thus far titanium steels have not won wide commercial acceptance. This subject will be expanded later. The orthodox ammonia nitriding process has been reviewed very adequately many times as in Jenkins3 and Case and VanHorn,4 and their is no need to outline the process here. Ion nitriding is not as well-known, although there have been several descriptions5-9 of the process given, sometimes with comparisons with the ammonia process. Most of these papers are primarily concerned with a description of the equipment, or of the physics or electrical engineering aspects of ion nitriding, but Noren and Kindbom9 gave the results of a metallurgical investigation using both processes. In brief, ion nitriding is carried out in a vacuum chamber from which the air is exhausted and replaced by a N2-H2 mixture, typically containing 10 to 20 pct N2, at about 5 to 10 torr pressure. While ammonia gas has also been used in ion nitriding, there is no evidence that ammonia makes any improvement in the ion nitriding process. A few hundred volts dc is applied between the grounded container wall (positive) and an insulated center post supporting the work (negative) to be nitrided. A glow discharge is created in the ionized gas, accelerating positive nitrogen ions to the work. These ions contain enough energy to form the normally unstable Fe4N "white layer", thus establish- ing surface nitrogen solubility characteristic of the a Fe/Fe4N equilibrium. This creates a substantial concentration gradient, driving dissolved nitrogen into the steel. The temperature employed is in the same range (around 500" to 550°C) as in ammonia nitriding, but because of factors which are not understood at present the nitriding time is ordinarily considerably reduced in ion nitriding. Other advantages have been cited,9 but it is not the purpose of the present work to contrast the two processes. The present objective was to examine the behavior of binary iron alloys during ion nitriding with respect to the microstructure, hardness level, and depth, and to examine some of these factors in steels as well. In this way it was hoped to be able to find out something about the individual role of these elements in steels. While all the work was done by ion nitriding, there seems to be no reason why any conclusions reached would not equally apply to ammonia nitriding, excepting only the kinetic aspects of the process. Another objective was an exploration of the critical-ity of the ion nitriding variables: gas composition, pressure, temperature, and time. EQUIPMENT AND MATERIALS The equipment used was substantially as described by Jones and Martin.8 The vacuum tank was about 12 in. in diam by about 18 in. high, and consisted of water-cooled stainless steel, with a single small window at the top for viewing inside. This sat on a heavy mild steel base equipped with the main pumping port, pressure control port, and vacuum gaging. A series of variable resistances was interposed between the glow discharge and a large-capacity -40 amp variable primary transformer feeding a 1000-v transformer, but 600 v were about the maximum ordinarily used. With the small l-in.-round, 4-in.-thick discs used for nitriding, the electrical load was usually about 500 v at 0.8 amp. The specimen temperature was controlled by a stainless-steel sheathed chromel-alumel couple, whose junction was in the steel stool upon which the flat discs were placed. These were ground through 400 Sic paper. Cycling of the temperature controller caused -0.2 amp variation in ion current, providing an ample control band. The binary iron alloys were made from vacuum-melted hydrogen-deoxidized electrolytic iron and alloys of 99.9 pct purity. Cast ll-lb-square tapered ingots were forged and hot-rolled to about 11/4-in.-diam rounds. Discs of 1/4 in. thickness by about 1 in. diam were machined from the rods for nitriding specimens. The following alloys were prepared: 1 pct each of Mn, Mo, Cr, Ti, Al, V, Si, and an Fe-0.8 pct C alloy. EXPERIMENTAL VARIABLES Of the variables total gas pressure, nitrogen partial pressure, temperature, and time, only nitrogen partial pressure was found to be critical to the operation. A critical nitrogen partial pressure was found corre-

Jan 1, 1970

By Kefton H. Teague

Attempts to locate domestic supplies of sillimanite have been unsuccessful until recently. This paper describes recent discoveries of sillimanite-bearing schists in the Southeastern States, with emphasis on geology of the deposits, mineral composition, origin, and reserves. Statements concerning possible methods of mining, milling, and utilization of sillimanite are given. Results from refractory tests on a laboratory scale are summarized.

Jan 1, 1950

By W. S. Ayres

I. Introduction. This cavern was discovered Oct. 32,1904, by Mr. Charles 8. Deutschman, in company with whom I made, May 29 to June 3,1905, at the request of Mr. Howard Douglas, Superintendent of the Canadian National Parks, the first exploration of it for the Canadian government. The results were stated in a paper, orally presented, with lantern-views from my photographs, at the British Columbia Meeting of the Institute, Victoria, B. C., July 5, 1905.* The present paper embodies also the results of a second examination, made Oct. 25 to 29, 1905. The accompanging map, Fig. 1, will serve as a guide to the following description. 11. Location. The cavern is situated at snow-line, at the head-waters of Cougar creek, on the west slopes of the Selkirks, about 2 miles north from Ross Peak water-tank, and 5.5 miles west from Glacier station, on the main line of the Canadian Pacific Railway. It was then reached by an arduous climb from the water-tank, up the ravine of Cougar creek, for 8,000 ft. (2,000 ft. of altitude) over rock- and snow-slides, and through a thick tangle of alders. But an easy and very picturesque trail has, during the past summer, been opened by the government from Glacier station, which is also a hotel of the railway company. Figs. 3, 3 and 4 represent views, not heretofore published, of the grand scenery of this region, so rapidly becoming the object of attraction to thousands of tourists from all parts of the world. These views, as well as those shown in Figs. 5, 6, 7, 8

Jan 1, 1908

By Blandford C. Burgess

Mica is an orchid among minerals. It is formed in pegmatites, one of the most bizarre of igneous formations, and is exceeded by few other minerals in the perfection it may attain as to size, color, and cleavage. First used for window glazing, as an ornament and article of trade, it has become one of the most essential insulators of electricity, heat, and shock. Most internal combustion engines use mica condensers or capacitors and such machines of war as planes, tanks, and submarines are immobile without it. The original manuscript of this guide was written in April 1943 at the peak of war emergency. It was not used be- cause shortly thereafter a decision was made to buy on a one price basis eliminating differentials for both quality and size. This is now presented with the thought that from the standpoint of preparedness we can only consider an- other war imminent and every effort should he made to set up in usable form the experience gained during the Second World War. Colonial Mica Corp. was set up by Metals Reserve Co. as a wholly owned government agency to encourage production of domestic mica and to purchase it. It soon became the exclusive buying agency for such mica. The writer as Southern Manager called on all the private agencies buying mica to assist in formulating buying policies, methods, and prices.

Jan 1, 1949

A PROSPECTOR stood atop a Venezuelan mountain called El Florero just 25 years ago, and shouted to the world that he had found a large, rich new source of iron ore. But his words were lost in the big green South American jungles and besides, the world had more iron ore than it could handle. There were no crises in 1926, no major wars on the horizon, no worries about mineral supplies. In the U. S., the populace was "keeping cool with Coolidge," and the solid foundation of the economy-the steel industry-rested on a still firmer basis, the Lake Superior iron ores.

Jan 5, 1951

By O. N. Carlson, E. D. Gibson, D. W. Bare

SEVERAL investigators have recently contributed to a clarification of the controversy concerning the allotropy of chromium. Ross and Hume-Rothery1 and Vasyutinskii et a1.2 have reported high-temperature X-ray data on unalloyed chromium from which they have concluded that no allotropic transformation occurs in this metal. Bechtoldt and vacher3 in their investigation of the Cr-Ni alloy system found no evidence for a transformation in chromium and Smart and Haynes4 in critically analyzing the data presented to date concerning this system could find no evidence for a eutectoid reaction in this system. Wyder and Hoch5 in research concurrent with our

Jan 1, 1964

By J. C. Bayles

Jan 1, 1886

By Steven Mitchell

BACKGROUND Homestake Mining Company began milling operations at the Bulldog Mountain Mine near Creede, Colorado in 1969. The Bulldog Mill, rated at 350 tpd, produces a bulk flotation condentrate assaying about 180 oz/T Ag and 20% Pb, from heads of about 16 oz/T Ag and 2% Pb. The circuit is straightforward with two-stage grinding to 1-5% plus 65 mesh, followed by rougher and cleaner flotation. Reagents used are Z-6, Z-11, Aerofloat 242 and Aero Promoter 404, with an Aerofroth 65-MIBC mixture for a frother. Additional information on the geology, mine and mill are available in references (1) and (2). A flow sheet for the mill and CIP plant together is attached as Figure 1. Final flotation tailings normally vary from 1.5 - 2.0 oz/T Ag. These tailings are cycloned to produce sand for underground backfill. After cycloning, the sands are repulped and given a final scavenger float. This sand scavenger recovers a small additional amount of silver which recycles back to the main flotation circuit. The tailings are recycloned and pumped to the mine or, if the mine cannot accept sand, to tailings. The majority of the silver in the flotation tailings exists in the fine fractions; cycloning upgrades the slimes and lowers the assay of the sand. The sand, after scavenging, typically assays 0.5 oz/T Ag, and the slimes assay about 3.0-3.5 oz/T Ag. From 1969 to 1976 all of the slime tailings and the sand tailings not used underground were impounded in a tailings pond located about

Jan 1, 1983

By George C. Branner

BAUXITE is produced in Arkansas from two mining districts in the central portion of the State. These are (1) the Fourche Mountain district, immediately south and southeast of Little Rock in Pulaski County, and (2) the Bauxite (town) district, about five miles east of Becton in the eastern part of Saline County. These two mining districts are about twelve miles apart, separated by territory which, so far, has produced a negligible amount of commercial ore. Mining was by open-pit methods exclusively until 1924, when underground methods came into use. From 1924 to 1930 about 40 per cent of all of the ore produced in Arkansas was mined by underground methods, mainly by retreating caving.

Jan 1, 1935

By J. Eric Belford

The Kidd Creek orebody is a massive base metal sulphide deposit with surface dimensions of 168 m by 670 m. The steeply dipping ore- body has been evaluated to a depth of 1 524 m. To date, the mining of the orebody has been divided into three stages. The first stage of mining was an open pit operation which supplied ore from 1966 until 1977 when a depth of 219 m was reached at the widest or north end of the orebody. The second stage of mining, called No.1 Mine, was the development of an underground mine to replace the pit and recover the ore from the floor of the pit to a depth of 792 m. Development of the underground mine started in 1969. Full production of 273 000 tonnes per month was attained in 1977. The third stage of mining called No.2 Mine, was initiated to accommodate a production expansion and included the development of a second underground mining operation to recover the ore from the bottom of No.1 Mine, i.e. the 2600 level; to a depth as yet undetermined but most likely the 4600 foot level. Development of the No.2 Mine began in 1974. Full production of 91 000 tonnes per month will be achieved in 1982. The choice of the 2800 level as the partition between the two underground mines was based on the following factors: The 2600 level is the lowest level which can conveniently be mined through the No.1 Mine crusher on the 2800 level. Development and trial stoping methods for mining at depth could be evaluated in the 2600 to 2800 block utilizing the existing hoisting facilities of No.1 Mine. Early development of the ore in the 2600 to 2800 block would provide additional mill feed sooner than could be achieved by developing from No.2 Shaft. The underground mining plan then is to mine from the pit floor down to the 2600 foot level and at the same time mine from the 2800 level down to at least the 4600 foot level. PLANNING The Kidd Creek operations are designed to follow a logical mining sequence. The grade of ore supplied to the concentrator is the result of following the mining plan. The philosophy of mining has been to mine downward in horizontal slices. In the case of No.1 Mine the slices are 122 m thick while in No.2 Mine the slices will be 183 m thick. The point of this approach is to mine the pillars immediately after creating them rather than allowing them to stand, deteriorate and generate uncontrollable situations. Two types of ore are handled separately to optimize recoverable values in concentrates. The 'A' type ore is a copper zinc ore with some silver and little lead. The 'C' type ore is a zinc silver ore with some lead and copper

Jan 1, 1981

By G. J. Ballmer

Drilling and blasting 12-in. blastholes started about the middle of 1946 and has worked out so well that about one half of the blasting, formerly done with 9-in. holes, is now done with 12-in. holes. In most of this work the harder benches were chosen for the 12-in. size because these were the areas where the greatest difficulty was encountered in thorough fragmentation. At the start of this experimental work a 42-T Bucyrus- Erie churn drill was available whereas all other blasthole drilling was being done with 29-T rigs. The large drill was first equipped with a standard 9-in. string of tools but it could not drill quite as fast as the 29-T drills. How- ever, when the weight of the string was increased about 700 lb, or to a total weight of about 3500 lb, it was found that the 42-T exceeded the drilling speed of the 29-T by about 25 per cent. When a 12-in. bit was substituted for the 9-in. bit the 42-T rig again dropped behind the drill- ing rate of the 29-T rigs. At this stage of the experiment the 42-T was using a 12-in. bit with detachable points and the total weight of the string of tools was about 3800 lb. It took longer to change the drill points than it did the regulation bit and this accounted for some of the slower drilling rate. When a heavier stem and standard construction 12-in. bits were used it was found that the 42-T could drill a 12-in. hole slightly faster than a 29-T could drill a 9-in. hole even in the hardest rock in the pit.

Jan 1, 1949

By AIME

BORN in 1899, in Bridgeport, Conn., E. A. Anderson grew up in a center of the nonferrous metal industry. Perhaps that had something to do with his selection of mining as a career while an undergraduate in Yale. After securing his Ph.B. in mining he worked for a year at Handy & Harman. By this time physical metallurgy had supplanted his interest in mining and he entered the Yale graduate school where he secured his M.S. degree in metallography under C. H. Mathewson. After completing his graduate work he entered the employ of The New Jersey Zinc Co. in their research division where he has remained ever since. The transition from graduate study to industry involved no disruption of technical interests. Academic research relating to the zinc-aluminum alloys, then coming into use for die-casting, was followed by extensive and productive industrial research in the perfection and commercialization of these alloys. Research on rolled zinc and rolled zinc alloys, corrosion and stress corrosion, dry cells, electroplating on zinc, and electrodeposition of zinc followed in overlapping succession as time passed.

Jan 1, 1947

By G. W. LAAiIBOURNE

FEW mines possess a history of more fascinating interest than the Ontario at Park City, Utah. The famous Bonanza's production record of over $50,000,000; the great extent of its workings; the remarkable character of its mineralization; the fact that recent discoveries have shattered preconceived theories of the geology of the camp practically assuring the half-century old property a future as active and as prosperous as the past make the Ontario one of the unique mines of the world. A mere accounting of the wealth created by this historic property not only exemplifies the great profits

Jan 1, 1925

R. W. Raymond, New York City: As was announced in the Secretary's note, appended to the pamphlet edition of Dr. Ledoux's paper, I have undertaken to superintend the preparation of the samples required by his plan, and the ollation for publication of the results reported. Promises of cordial co-operation hare been received already from a number of leading assayers;? and it is to he expected that the data thus collected, and the discussion to be based upon them, will shed much light upon the important question raised in this paper. Although a detailed discussion of methods on the present occasion might be deemed premature, I am sure that suggestions on the subject from members engaged in assaying would be timely and valuable as a preliminary to later and more detailed criticism. Herbert G. Torrey (U. S. Assay Office), New York City : I may say in relation to the losses in the furnace that I have made a number of experiments, and on my little blank form years ago I put down a place for the losses in the cupel. It met with a good deal of opposition among the smelters, but I claimed that it was my duty to give the full amount of the gold and silver present, and that it

Jan 1, 1895

By A. P. Svenningsen

DURING the work at the test mill in Morenci, it was determined that a suitable feed for the ball mills could be made by a single pass through a short-head cone crusher. These crushers did not require a closed circuit delivering only a screen product to the mills, such as is the practice in some concentrators. By no means does this mean that the practice in these other concentrators is wrong, but just that the Morenci ore can be most economically crushed and ground in this manner. Therefore, the design of the secondary crushing plant was simply a problem of taking 25,000 tons of ore per 16 hour day from the primary crusher, this ore ranging in size from fine particles to 10 or 12 in., and reducing it to minus 3/4 in. Inasmuch as outages must be contended with in any crushing plant, it was assumed that the crusher would operate at full capacity for approximately only twleve hours per day, which is three-quarter capacity for the 16-hour shift. With this in mind, it was necessary to design a crushing plant which would average approximately 1600 tones per hour for the 16-hour day, or 2000 tons per hour for slightly over 12 hours per day.

Jan 1, 1942

By Philip D. Wilson

WHEN the United Nations win the war and the decision has been made to control future armament in the Axis countries, plans for the extent and operation of such control must have been prepared, to be ready to put into immediate execution. Such control to be effective must be premised upon complete military occupation of the two countries for a substantial period, with an arrangement at the end of such occupation for continued supervision of these industries into an indefinite future.

Jan 1, 1944

By G. D. TRANT

HOT metal is commonly transported from the blast furnace to the open hearth by one or the other of two general methods: (1) by hot-metal ladles, usually in conjunction with a stationary mixer, or; (2) by means of mixer-type ladle cars, taking the place of both the hot-metal ladles and the stationary mixer. In both cases, the use of transfer ladles for charging the metal into the open-hearth furnaces is necessary. The American Rolling Mill Co. at its Middletown division, adopted hot metal practice on. June 2, 1928. The pig iron is produced' in a .blast furnace about 11 miles from the open-hearth furnaces, and is trans- ported in Pugh-type mixer cars having a capacity of 150 gross tons each. Three cars are in service and handle the delivery of hot metal to the pig machine and the open-hearth furnaces. The capacity of the blast furnace is 550 tons and casts are made every four hours.

Jan 1, 1929

By AIME AIME

TWENTY-TWO sections and all four of the divisions sent delegates to the annual meeting. They became so interested in the wide ranging dis6ussion of old and yet ever-new problems of Institute affairs that three instead of two sessions scheduled were necessary. Monday morning the meeting assembled with President Bassett presiding in the absence of President-elect Tally, who had been called to Baltimore by the serious illness of a brother. Thursday morning Vice-president Turner presided until Mr. Tally appeared after which the latter guided the sessions. Since reports from all of the active sections save one had been mimeographed and sent in advance to the delegates, detailed reports from each were dispensed with. The discussions dealt largely with membership problems, both local and national, with financing, speakers and programs, visits from national officers, and the conduct of the annual meeting. Many interesting and constructive suggestions were made and will be reported back to the sections by the delegates.

Jan 1, 1931

By Russell Webster

In having maintained production for more than 40 years Arizona's Magma mine is unique in a mineral district that includes several major copper mines. Other past and present producers in this area are Miami and Inspiration at Miami, the Old Dominion in Globe, the Ray mine in Ray, and to the south the new San Manuel mine near Tucson. Magma's production of copper, silver, gold, and some zinc has come from nearly parallel east-west striking mineralized faults, one called the Main or Magma vein and the other the Koerner vein, about 1100 ft to the south. This vein system has been prospected and partially mined for some 9000 ft horizontally and 4800 ft vertically. In ascending order from the deepest exploration level, the Main vein cuts Pre-Cambrian schist, Pre-Cambrian Apache Group, Post-Devonian diabase, and Devonian, Mississippian, and Pennsylvania limestones. Until 1950 very little ore was obtained from replacement mineralization.

Jan 10, 1958