Search Documents

By David W. Brunton

FROM the old-fashioned " grab-sample " to the modern timing- . device, which takes a machine-sample with mathematical precision, there is a wide gap which was only crossed' by many years of toil and unremitting endeavor. Even to-day, notwithstanding the advancement in the art, "grab-sampling" is still practiced-sometimes to afford the unscrupulous mine-promoter a basis for fairy-tales with which to entrap the too-gullible investor, and often by milling and smelting companies to determine the amount of moisture in custom-ores. The latter practice is almost as reprehensible as the former, and it causes more trouble and ill-feeling between seller and buyer than all other factors put together. No reputable concern to-day would think of attempting to determine by grab-sampling the amount of gold, silver, lead, or copper contained in an ore, and yet many buyers expect the miner to accept the results of grab-sampling in the determination of the amount of water contained in the ore, forgetting that accurate results are just as necessary here as in the determination of the metals, because the result determines the percentage of weight of the ore which shall be excluded and considered to have no value whatever. Samples for the determination of moisture should be taken with as great care as samples for the determination of. metallic content, and in order to avoid the extra expense of a separate operation moisture-samples should be taken from the sample-safe. As the sample reaches the sample-bin in a smaller stream and by a more circuitous route than the "reject" travels in its path to the outgoing car, it loses more moisture en route, and a constant should be added to compensate for this difference. Carefully-conducted experiments have shown that the difference in loss of moisture between the two routes does not exceed 10 per cent. in summer and 7 per cent.. in winter. For instance,

Aug 1, 1909

By Joseph E. Pogue

The writer visited the Muzo emerald mines in July, 1915, and spent six days in their study. This paper embodies the results of his observations, plus information personally communicated by Robert Scheibe, Professor of Geology in the Mining Academy of Berlin, who at the time of the visit was completing a detailed field investigation of nearly a year's duration of the emerald deposits of Colombia. An elaborate account of this valuable work may be expected at a future date from the pen of Professor Scheibe.

Jan 1, 1917

By T. B. Nolan, R. N. Hunt

In terms of present metal prices, analysis of extant records of the Eureka district indicate past production of the magnitude of $200,000,000 in recovered silver, lead, and gold. Production to date has been thoroughly oxidized ore from massive replacements, fissures, manta, and pipe-like bodies-in large part from the massive Eldorado (middle Cambrian) and Hamburg (middle to late Cambrian) dolomite horizons. In the productive area of about 6 square miles carbonate rocks comprise 80 per cent of the section, which includes early Cambrian to late Ordovician horizons. Four-fifths or more of the district's production came from a block of Eldorado dolomite in Ruby Hill that was moved in over younger horizons on strands of a regional thrust fault. The lower 500 to 600 feet of the block was much fractured and brecciated and became host to the ores. The Ruby Hill fault, a late normal fault, limits the Ruby Hill block of dolomite on the north for its entire length of nearly a mile and terminates the downward extent and exploitation of its ores. It introduced an hiatus of some 40 years in the district's development. Drilling of the past 20-odd years, followed by underground work, has now exposed the down-faulted extension of the Ruby Hill block of Eldorado dolomite and its contained ores, dropped 1800 feet in a dip shift to depths beneath the surface of 2000 to 3000 feet. The ores at depth are the sulfide counterpart of those mined in early years on the footwall side of the fault. The ores of the district may be attributed to the same source as the intrusive quartz diorite outcropping in a limited way south of Ruby Hill but found at depth elsewhere in drill holes. The long north-south axis of the district, its anticlinal structure, its major faults, and the distribution of the intrusives and, in their relation to the surface, the ores themselves, all suggest that erosion has not cut deep enough to expose the extent of intrusives and the ores consequent upon them.

Jan 1, 1968

By Davis M. Lapham

Ore bodies at Cornwall, Pennsylvania, have been mined since 1742 principally for iron from magnetite, but also for copper (in chalcopyrite), silver (in chalcopyrite), gold (in chalcopyrite), cobalt (in pyrite), sulfur, and crushed limestone aggregate. Metallization occurs as a limestone replacement above the essentially conformable, south dipping portion of a discordant saucershaped diabase sheet. Pre-Triassic and Triassic faulting have emplaced host Cambrian limestone and two Ordovician(?) hornfels units, now for the most part resting above diabase. Thermal metamorphism of carbonate-bearing country rocks largely to calc-silicates, is ubiquitous. Metasomatism, particularly of potassium, is unique to ore zones. Associated magnetite- actinolite mineralization replaces, in a preferential sequence, all earlier metamorphic and metasomatic minerals and rarely diabase chilled margin. Mineralogical (diopside, actinolite, mica, sulfides, oxides) and chemical (Fe, Cu, S, Co) zoning of the eastern ore body is focused down dip, near its western edge, along a major vertical fault through diabase. This zoning is spatially related to magnetite veins in diabase, to an ore body within diabase, and to a shear zone that probably extends through the sheet.

Jan 1, 1968

By Goerge F. Weaton

Since 1909, when an agreement between Minnesota's Tax Commission and the University of Minnesota's School of Mines was worked out, it has been the annual responsibility of the School to evaluate and classify the iron ore deposits within the State. These unique duties of an academic institution have provided School officials with an excellent view of the past, present and probable future of the mining industry in Minnesota as the average grade of iron ore (excluding taconite) * diminishes while at the same time it competes with beneficiated taconites and foreign high-grade ores for use in America's eastern blast furnaces. SYSTEM OF EVALUATION In the latter part of November of each year, the Mining Division of the Department of Taxation makes a preliminary study of the active mines which the Department wants the School of Mines to review. These are discussed with the engineers of the Ore Estimate Division of the School of Mines and with the mining companies. After these discussions, a list of the mines of each of the major operating companies is submitted to the Ore Estimate Division of the School of Mines with the request that these properties be reviewed by them as of the next assessment date (May 1st). At the same time, a letter is sent to the mining companies requesting that they submit to the Division their own estimates on the selected mines operated by them, together with all computations, drill records, maps and cross-sections. The mining companies are re- quested to send in this information during the first half of the year, and, as far as is possible, they have always complied with this request promptly. Much of this information received by the School of Mines is of a confidential nature and is treated as such.

Jan 1, 1965

By George Burrell

J. S. HALDANE, M. D., F. R. S., Oxford, England (communication to the Secretary?).-The valuable paper of Messrs. Burrell and Gauger is of special interest to me as, through the courtesy of the management, I had an opportunity of visiting the Portland mine, Cripple Creek, in 1911, in connection with the investigations on acclimatization to high altitudes, carried out on Pike's Peak, near Cripple Creek, by Professors Yandell, Henderson and Schneider, Dr. Douglas and myself.1 The analyses of one or two samples of the vitiated air were entirely confirmatory of those of the authors. A fatal accident owing to two men being lowered down a shaft filled with the gas had occurred in a neighboring mine just before our visit.

Jan 12, 1916

By G. A. Beiswenger

The application of the law of supply and demand to the sale of crude oil is generally conceded, but the motives underlying the buyer's (refiner's) demands are not always obvious to the seller (producer). In some cases this obscurity has led to the conclusion that the refiner may be unnecessarily particular when he selects one crude and rejects another. This preference, however, is very largely the reflection of the refiner's product demands and the quality of the stocks obtainable from the selected crude. The purpose of this paper is to point out critical characteristies of the major classes of refined products and to show how crudes vary in their suitability for such products. With relatively few exceptions, available processing methods and addition agents make it theoretically possible to produce any type of refined product from any crude source, although it may not be economically sound to do so. The widespread application of thermal cracking for converting higher boiling stocks into gasoline is well known. More recently cracking and refining in the presence of catalysts9 have been developed, as well as various processes for polymerizing lighter hydrocarbons into gasolines having desirable characteristics.6 For several years, selective solvents have been applied commercially to refining inferior quality kerosene, Diesel fuel and lubricating oil distillates.3 Improved methods for refining lubricating oils from crude residual4 formerly suitable only for fuel, are now in use and a number of special solvent processes are available for dewaxing lubricating oils to low pour point.5 These improved refining methods have been developed not only to meet the demand for improved product quality but also to enable the refiner to obtain quality products from crude sources that would not yield such products by the older refining methods. In many cases, the utilization of these modern refining tools necessitates an appreciable expenditure for equipment as well as added manufacturing costs, and their application therefore must be justified economically. Despite the availability of such tools, the added processing costs involved and yields obtainable may render their application entirely impractical. To illustrate this point, inspections of typical cuts from various crudes

Jan 1, 1940

By Clyde E. Williams, JAMES L. GREGG

THIS review of the past year's progress in iron and steel metallurgy presents examples of only a few of the interesting or important accomplishments made in the United States. In the field of iron ore concentration increased attention was given to the study of the more difficultly separated wash ores and some progress was made in tabling. One difficulty with the table, in concentrating iron ore where the percentage of concentrate in the feed is large, has been the removal of fine silica from the thick layer .of concentrates in the cleaning zone. One company has -Made an important contribution toward the solution of this problem by an extension of the well-known plateau principle. By a special riffling of the plateau section of the table, the concentrates are crowded together. This action forces the fine silica to the top of the bed in the cleaning zone, whence the cross-flowing currents of water -can wash it into the middling product. Some work has been done on the application of froth flotation to the concentration of iron ores. Laboratory experiments were made at the Colorado School of Mines in which hematite was, successfully floated. Using oleic acid as a frothing and collecting agent and sodium carbonate as the conditioning agent, a high recovery of rich ,concentrate was obtained. A laboratory flotation unit is in use at Taconite, on the Mesabi range, and a commer-

Jan 1, 1932

By Charles W. Frey

SUCCESSFUL mining today means proper mechanization. Before any mine can begin production on a paying scale, some machinery must be installed. There must be pumps to remove water, fans and blowers to provide proper ventilation, elevators and hoists to raise materials, and a source of power to turn the countless wheels on which the world's mineral supply rolls from its earthhound source to the market. Only the prospector with his burro and the anthracite "bootlegger" continue to mine without mechanical aid, and with the recent years even these can be discounted, for the burro has given way to the Model T, and the "independent" coal miner must have a truck to haul his coal away. The few types of machinery mentioned above are but a beginning. The

Jan 1, 1938

By G. A. Beiswenger

The application of the law of supply and demand to the sale of crude oil is generally conceded, but the motives underlying the buyer's (refiner's) demands are not always obvious to the seller (producer). In some cases this obscurity has led to the conclusion that the refiner may be unnecessarily particular when he selects one crude and rejects another. This preference, however, is very largely the reflection of the refiner's product demands and the quality of the stocks obtainable from the selected crude. The purpose of this paper is to point out critical characteristics of the major classes of refined products and to show how crudes vary in their suitability for such products. With relatively few exceptions, available processing methods and addition agents make it theoretically possible to produce any type of refined product from any crude source, although it may not be economi-cally sound to do so. The widespread application of thermal cracking for converting higher boiling stocks into gasoline is well known. More recently cracking and refining in the presence of catalysts9 have been developed, as well as various processes for polymerizing lighter hydro-carbons into gasolines having desirable characteristics.6 For several years, selective solvents have been applied commercially to refining inferior quality kerosene, Diesel fuel and lubricating oil distillates .3 Improved methods for refining lubricating oils from crude residua,4 formerly suitable only for fuel, are now in use and a number of special solvent processes are available for dewaxing lubricating oils to low pour point.5 These improved refining methods have been developed not only to meet the demand for improved product quality but also to enable the refiner to obtain quality products from crude sources that would not yield such products by the older refining methods. In many cases, the utilization of these modern refining tools necessi-tates an appreciable expenditure for equipment as well as added manufac-turing costs, and their application therefore must be justified economically. Despite the availability of such tools, the added processing costs involved and yields obtainable may render their application entirely impractical. To illustrate this point, inspections of typical cuts from various crudes

Jan 1, 1940

AT the fall meeting of the Iron and Steel Division, Oct. 4, 1934, in New York, a symposium was held on Slag Control in the Making of Iron and Steel. The chairman was J. H. Nead and the vice chairman, G. B. Waterhouse. The latter presided at both morning and afternoon sessions. The papers and discussions were presented in the order in which they appear on the following pages. To meet space requirements, much of this material has been considerably condensed. CONTENTS [ ]

Jan 1, 1935

By AIME AIME

THE stage is set for the 1930 Annual Meeting. It will take place in the Engineering Societies Building. Feb. 17, 18, 19 and 20, and an unusual pro- gram of technical papers, symposia, lectures and addresses, interspersed with luncheons, dinners, excursions and worthwhile entertainment for the four days has been arranged. The curtain rises on Monday morning and the first act is by the entire company-registration. Then the meeting hits its stride, for there are ten technical sessions on Monday, and the range of subjects includes most of the Institute membership. The Committee on Coal and Coal Products, which is about to become the Coal Division, presents a symposium of a dozen or more papers on Coal Classification, concluding its afternoon session with several papers on general subjects. At its luncheon between sessions, C. E. Bockus, president of the National Coal Association, will be the honored guest. Papers of theoretical character will be discussed at the morning session of the Committee on Geophysical Prospecting; at its afternoon session there will be presented summaries of results obtained at various properties by methods described at previous meetings of this group and permanently recorded in "Geophysical Prospecting," published by the Institute early in 1929. Members of the Petroleum Division should not overlook the paper by Theodor Zuschlag, on this Committee's program. It is entitled, "Oil Structure Mapping by the Sundberg Method." Members of the Iron and Steel and Institute of Metals divisions will find it profitable to attend the session on Engineering Education on Monday afternoon. E. A. Holbrook has arranged a program of ten-minute talks on Metallurgical Education which are designed to get down to "brass tacks." and the practical man may, in discussion, contribute as well as learn. At 5 p. m. Thomas T. Read will lecture+ at Columbia University, on "Recent Progress in Economics of the Mineral Industries."

Jan 1, 1930

By Oliver Bowles

A NORTH CAROLINA miner dreamed that he found high-grade mica by excavating a certain corner of his mine. The next day he sank a hole on the exact spot and found mica of excellent quality. The dream came true. May not this be as good a method as any yet known for forecasting the valuable mineral content of pegmatites? The Federal Geological Survey has found in its recent detailed studies in New England that good sheet mica occurs most abundantly in zoned pegmatites, particularly in zones lying along the wall or contact of the pegmatite mass. Although this conclusion may be a valuable guide, pegmatite mining operations must still be classed as most uncertain and hazardous enterprises. Finding of the second largest diamond ever discovered in the United States-a stone of good gem quality weighing more than 34 carats-during the course of a horseshoe pitching contest at Peterstown, W. Va., is another example of unorthodox mining methods. These should not be considered, however, as characteristic mining methods developed in 1944.

Jan 1, 1945

The House Committee of the Engineering Societies Building has lent to he members of the three welfare committees a room on the ground floor of the building where they can carry on some of their war activities. Two sewing machines and two knitting machines are installed there and ladies are invited to sew for the Foreign War Relief Committee and knit for the Emergency Committee, which is working for the 27th Engineers, a special mining regiment. The Emergency Committee, Mrs. H. Norman Spicer, Chairman, reports the formation of a committed of 21 members. The organization meeting was held March 7, and plans were made for future activities as follows: A letter was read from Mr. Ingalls asking for 72 sweaters, 72 helmets, 66 pairs of wristlets as well as 772 pairs of socks, 272 being for immediate delivery. To meet this request it was decided to secure the helmets and wristlets from the Navy League, and to undertake the making of the sweaters and socks ourselves. Accordingly Mrs. H. N. Spicer and Mrs. J. H. Devereux were empowered to buy wool in sufficient quantities, and woven material for the 72 sweaters, sending the bills to Mr. Ingalls, who had guaranteed the money from the Engineering and Mining Journal. This was attended to promptly, and the materials were ready for distribution to the committee on March 13. After considerable difficulty, knitting machines for the socks were discovered and the agent came to demonstrate them. Mrs. Spicer gave one to the Committee and Mr. Ingalls has guaranteed the money to buy two when the manufacturers can deliver them. Up to April 6, 130 pairs of socks, machine and hand-knitted, have been handed in-also 68 sweaters, 80 helmets and 90 pairs of wristlets. It has been calculated that it needs five women knitting behind each man at the front to keep him continuously supplied with knitted garments.

Jan 5, 1918

By Ralph W. Marsden

The natural iron ores of the Lake Superior Region in the United States are being replaced by iron-ore concentrates produced from magnetite- or hematite-rich horizons in the Precambrian cherty iron formations. The production of natural ores will soon be less than one-half of the total ore shipped annually. The tonnage of natural ore produced will continue to decline until it is a minor percentage of the ore shipped. The natural ores include (1) soft ore, (2) hard ore, ( 3) conglomerate ore and ( 4) siliceous ore. The soft ores are the important ore type and are sometimes termed "Lake Superior type ore". These ores are in situ deposits of hematite and limonite formed by the leaching of silica and other gangue materials in the iron formations. The leaching is believed to have been done by downward moving surface waters. In deep ore deposits, generally over 1000 feet below the present surface, circulation and leaching action may have been assisted by hydrothermal activity. Hard ore deposits occur on the Vermilion and Marquette ranges where hematite or magnetite has replaced the silica (and possibly some silicates) in cherty iron formation. These ores commonly occur in structural situations favorable for the movement of hydrothermal waters. The ores are believed to be the result of hydrothermal action with iron, possibly from the iron formation, transported by hydrothermal waters to areas favorable for the replacement of silica by iron oxides. Certain stratigraphic horizons of the Lake Superior Precambrian cherty iron formations contain sufficient iron as magnetite or hematite, with a grain size and texture that will give adequate mineral liberation, to yield an ore-quality product after grinding and concentration. The magnetite-rich deposits are termed magnetite taconites. These ores occur on the Mesabi, Gogebic, and Marquette ranges. Magnetite taconite ores are unenriched cherty iron formation and are the result of the sedimentary deposition of the iron formation and the metamorphic history of the rock. The commercial quality hematite-rich iron formations in Michigan are termed jasper ores. The jasper ores are being mined on the Marquette and Menominee ranges. These ores are composed of specular or granular hematite associated with quartz and iron silicates. The jasper ores appear to be recrystallized iron formations in which iron, prior to recrystallization, occurred as hematite.

Jan 1, 1968

By David B. Dill, Edgar R. Lea

The zinc deposits of the Balmat-Edwards Division of the St. Joseph Lead Company in northern New York State provide some 10 per cent of the domestic zinc produced annually within the United States. These complex ore deposits are contained within marbles of the Precambrian Grenville series, in a repetitive sequence of dolomites and silicated units. The Balmat ore bodies are localized at various intervals throughout some 1800 feet of the stratigraphic column on the northwest side of a band of gneiss that has continuity to the Edwards area, some 10 miles to the northeast. The Edwards ore bodies are located to the southeast of this gneiss. The marble formations are thought to have included repetitive intervals of marine sedimentation that provided mineralized source "beds" and were subsequently folded, flooded, and injected with melts at great depth and were sheared, recrystallized, and reconstituted. Detailed structural and stratigraphic studies throughout the northwestern Adirondacks, in the Balmat-Edwards district, and at each mine in particular indicate the close dependence of the ore deposits on the enveloping structure whether it be local, district-wide, or regional in scope. Primary folding has developed a northeast regional trend with northwest dips. Secondary folding has been developed by an almost horizontal northeast-southwest-oriented shear couple in the plane of the regional trend. The secondary folding has produced crossfolds that intersect the regional northeast trend and plunge north to northwest at various angles. The ore bodies are found within certain stratigraphic horizons where repeated alternation of competent and incompetent beds encouraged unusually complex folding. Analysis of individual mine structures indicates that the location of each deposit is controlled by structural crossing of primary and secondary folding. The ore bodies, which are tabular, lenticular, or pod-like in form, have features that suggest parallelism to true bedding or modified flow banding, developed by northeast-southwest shearing stresses related to the development of the crossfolds. The ore deposits in general follow both structural and recrystallization trends within the wall rocks. Mobilization of the pre-metamorphic ore minerals is believed to have involved a combination of plastic flow under stress and solution of the sphalerite, minor galena, and pyrite. The ore fluids are thought to have been guided by secondary shearing and microbrecciation into structurally prepared areas where reprecipitation took place. The presumed premetamorphic mineralization now exhibits epigenetic high-temperature features related to late-stage metamorphism.

Jan 1, 1968

By H. E. Wheeler

THE work described was carried out during 1917 and 1918 at the testing laboratory of Watertown Arsenal at the instigation of the Nitrate Division and later with the concurrence of the Cannon Section of, the Ordnance Department, U. S. A. The experiments follow three principal lines of work: First, the effect of nitrogen under pressure on steel containers of various compositions at a red heat; second, the effect of decomposing ammonia on various alloy steels, iron, and non-ferrous alloys; third, a new theory of the erosion of guns in respect to the effect of nitrogen in steel. PART I In the Haber process for the manufacture of ammonia from its elements, it is necessary to have nitrogen and hydrogen of 1500 lb. per sq. in. (105.5 kg. per sq. cm.) at a temperature of 500 to 600° C. The steel containers for these gases gave trouble by failing without apparent cause. When the General Chemical Co. began to develop its method for the production of ammonia, it experienced the same difficulty and, knowing that the Haber process had solved the difficulty by the use of alloy steels, it made several small steel bottles of different compositions and kept them filled with these gases at this pressure and temperature until they failed. The time of service varied from a few days, for the plain steel casting, to two years for a chrome-vanadium forging. Four of these steel bottles were sent to this laboratory for investigation; they were a plain carbon-steel forging, a nickel-steel forging, a chrome-vanadium steel forging, and a chrome-steel forging. The time of service was as follows: plain carbon steel, 4 mo.; nickel steel, 6 mo.; chrome-vanadium steel, over 2 yr.; chrome steel, 4 mo. When these containers were cut open and the cross-section surface polished, they showed an inside zone with a different luster from the rest of the metal. Upon etching, this zone was almost unaffected while the rest of the steel etched normally.

Jan 4, 1920

By C. A. Stetefeldt

Jan 1, 1895

By Pierre R. Hines

These notes are based on observations made while on a recent trip through the West, for the purpose of studying the practical operation of the ball-mill. The writer takes this opportunity to express his thanks for courtesies extended at the many plants visited as well as for the valuable data received: While there are several types of ball-mill on the market, particular attention will here be given to the diaphragm type, as the open-trunnion type, especially the conical mill, has been thoroughly discussed in the Transactions. There is a prevailing impression that the ball-mill is a recent development; however, ball-mills were used extensively in Montana and other western states for crushing ores for concentration as far back as 1808. Its present prominence is due in part to its recent successful application by one of the large copper companies. Without any reference to dry grinding, the first successful ball-mill for wet crushing, which is still in operation, was built 10 years ago.l This mill, designed by Erminio Ferraris for crushing Sardinian ores for concentration, is of more than passing interest. It embodies the peripheral discharge with grates, large forged-steel balls, and the principal features of the modern ball-mill. The results approach present-day practice, the chief differences being that the mechanical construction has been improved in the modern types. Crushing Action of Ball-mill The action of the balls and the principles of crushing have been studied by several investigators.2 Their conclusions are confirmed by results obtained by the writer in experimenting with a small machine built at

Jan 1, 1918

By George Holderer

THE Enos Coal Mining Co. owns an area underlaid by coal, of approximately 5000 acres. This property is situated 9 miles from Oakland City, in the southern part of Indiana. The mine has been in operation 5 years, during which time some 350 acres have been stripped, and stripping is now proceeding at the rate of about 100 acres per year. TOPOGRAPHY These coal lands consist of gently-rolling agricultural fields which in times past were farmed for wheat. There is no timber and but very little brush to contend with. The overburden varies from 10 to 60 ft. in depth. A thin bed of slate overlies the coal, followed by limestone, which varies from 3 to 15 ft.; this, in turn, is followed by sandstone, slate, shale and clay. There is a very wide variation in the thickness of all of these beds. The coal has an average thickness of 5 ft., and is a good grade of high-volatile bituminous. MINING OPERATIONS Briefly, the sequence of operations is: drilling holes with churn drills; blasting with L. 0. X.; stripping overburden to uncover coal and, finally taking up the coal, which is sent to a tipple for cleaning and sizing. In order to show what is being accomplished by the use of L. 0. X., results will be shown from May to November, 1926, inclusive, and compared to the same period in 1925. No work was done in No. 1 pit during May, 1925, hence all figures are unduly low for this month. Drilling There are in use 8 No. 44 Loomis clipper drills, caterpillar traction with gasoline engines; recently these were equipped with extra heavy stems, measuring 26 ft. overall and 4 ½ in. dia., to increase the speed of drilling. In addition, 4 No. 1 ½ G non-traction drills have been acquired, and are used to save the time of the larger drills when recleaning is necessary.

Jan 1, 1927