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By Douglas W. Fuerstenau, Kalanadh V. S. Sastry

A mathematical model is developed for flotation in a countercur-rent column where continuously generated air bubbles rise through a downward flowing pulp. The model is based on the assumption of axially dispressed plug flow of both the liquid and air-bubble phases. An appropriate flotation-rate expression, which takes into account the changing concentration of solid particles on the bubble surface, is formulated and applied to the column flotation process. Although a complete solution of the resulting equations is not possible for the general case, solutions for specific limiting cases have been obtained. From these, it is possible to predict theoretically the dependence of the column performance on certain variables. Specifically, concentration profiles as a function of height in the column have been calculated for various values of the characteristic dimensionless parameters. The effect of axial dispersion on the perforance of the equipment is pointed out. In recent years, there has been considerable progress in delineating the fundamental physicochemical principles underlying the unit operation of flotation and in advancing methods for kinetic analysis and process modeling of flotation.' In general, nearly all such process research has been concerned with the analysis of conventional flotation equipment and circuits. From these investigations, the possibility of developing and designing flotation apparatus for more efficient separation appears limited with conventional equipment. How- ever, recently there has been an attempt to apply coun-tercurrent flow techniques to flotation in the context of a flotation column.- some of the results from pilot-plant studies2 indicate possibilities for success of this process at least in obtaining higher-grade concentrates though not higher recoveries. A flotation column operates on countercurrent principle in which bubbles continuously generated at the bottom of the column rise through the downward flowing slurry. A schematic diagram of the flotation column is shown in Fig. 1. The physicochemical principles of bubble-mineral attachment, using this flotation column, are essentially the same as those which prevail in conventional equipment, the only differences being in the flow patterns of the various phases. The salient operating feature of the column as compared to those of a conventional cell is that neither mechanical nor turbulent pneumatic agitation is employed. The column is

Jan 1, 1971

By A. S. Richardson

THe conditions that make necessary the mechanical ventilation of the Butte mines of the Anaconda Copper Mining Go. are due to a number of causes, all of which are incidental to the depth at which mining operations are now carried on, The main object to be accomplished, of course, is the reduction of the temperature and humidity of the air in the working places. Ventilation fans, both surface and underground, have been used for many years, but increasing depth has made the problem much more difficult. Further improvement in both ventilation equipment and methods, therefore, became necessary; and it is the purpose of this paper to describe the work planned and done under the improvement program. The mines of the district have been frequently described in various technical publications, so a description is unnecessary here. From a mine-ventilation viewpoint, compared with coal-mine ventilation systems, the problem is complicated by the fact that the workings to be ventilated are situated on a large number of steeply dipping veins which frequently intersect and are faulted, and also by the fact that the extent, or existence, of orebodies is not definitely known in advance of actual development work. For these reasons ventilation work cannot be planned in advance of actual operations, nor can such regular systems of ventilation as are used in working the more uniform and continuous bodies of coal be developed. When operations are conducted at a normal rate, about 10,000 miners are employed on two shifts, so that about 5000 men will be underground at one time. But as ventilation is necessary to reduce high temperature and humidity due, mainly, to natural causes, the quantity of air per man per minute is not a governing consideration in determining ventilation requirements. Most important among the numerous sources of heat and humidity in the mines are: heat generated during decay of mine timber; heat and humidity given off by mine rock and water; heat generated by oxidation of sulfide minerals; heat given off by electrical equipment; heat generated by mine fires (in certain localities).

Jan 1, 1923

By A. S. Richardson

THe conditions that make necessary the mechanical ventilation of the Butte mines of the Anaconda Copper Mining Go. are due to a number of causes, all of which are incidental to the depth at which mining operations are now carried on, The main object to be accomplished, of course, is the reduction of the temperature and humidity of the air in the working places. Ventilation fans, both surface and underground, have been used for many years, but increasing depth has made the problem much more difficult. Further improvement in both ventilation equipment and methods, therefore, became necessary; and it is the purpose of this paper to describe the work planned and done under the improvement program. The mines of the district have been frequently described in various technical publications, so a description is unnecessary here. From a mine-ventilation viewpoint, compared with coal-mine ventilation systems, the problem is complicated by the fact that the workings to be ventilated are situated on a large number of steeply dipping veins which frequently intersect and are faulted, and also by the fact that the extent, or existence, of orebodies is not definitely known in advance of actual development work. For these reasons ventilation work cannot be planned in advance of actual operations, nor can such regular systems of ventilation as are used in working the more uniform and continuous bodies of coal be developed. When operations are conducted at a normal rate, about 10,000 miners are employed on two shifts, so that about 5000 men will be underground at one time. But as ventilation is necessary to reduce high temperature and humidity due, mainly, to natural causes, the quantity of air per man per minute is not a governing consideration in determining ventilation requirements. Most important among the numerous sources of heat and humidity in the mines are: heat generated during decay of mine timber; heat and humidity given off by mine rock and water; heat generated by oxidation of sulfide minerals; heat given off by electrical equipment; heat generated by mine fires (in certain localities).

Jan 1, 1923

By John B. Dilworth

In September, 1930, H. N. Eavenson, then Chairman of the Coal Division, appointed a Committee on Methods of valuing Coal Propelvties, with John B. Dilworth as chairman. The latter prepared a schedule' of features for consideration under the general headings of Undeveloped and Developed Coal Properties. These subjects were divided among the members of the committee and during the next year written discussions of his allotted subjects were received from each member. Mr. Grimes and Mr. Eavenson discussed the entire list,. These discussions were mimeographed and a set sent to each member before the meeting of the Institute in February, 1932. There was a general discussion at that meeting. At the meeting in February, 1934, Mr. Dilworth submitted a report12 which summarized the accumulated opinions and data and presented the conclusions of the committee as a whole on the subjects embraced in it's schedule. Members of the committee expressed the desire that some of the individual opinions be published for reference. Mr. R. Damon Hall's abstracts of these papers arc therefore presentrd herewith.3 Personnel of Committee John B. Dilworth (Chairman), Consulting Mining Engineer, Edward V. D'Invilliers Engineering Co., Philadelphia, Pa. Eli T. Conner, Consulting Mining Engineer, Seranton, Pa. W. G. Duncan, Jr., Superintendent, W. G. Duncan CoaI Co., Greenville, Ky. Howard N. EAveNson, Consulting Mining Engineer; Eavenson, Alford & Hicks. Pittshurgh, Pa. George Watkin Evans, Consulting Mining Engineer, Seattle, Wash. J. A. Garcia, Consulting And Constructing Engineer, Allen & Garcia Co., Chicatgo. III. John Alden Grimes, Valuation Engineer, Bureau of Internal Revenue, Washington, D. C. Otto Herres, Assistant Manager, United States Fue1 Co., Salt Lake City, Utah. J. R. Hicks, Consulting Mining Engineer, Eavensorl, Alford & Hicks, Pittsburgh, Pa. Robert D. Reeder, Mining Engineer, U. S. Bureau of Mines, Washington, D. C. Samuel, A. Taylor, Consulting Engineer, Pittsburgh, Pa. Bleeckee L.. WHeeler, Mining Engineer, Ford, Bacon & Davis, New York, N. Y.

Jan 1, 1934

By W. L. Dennen, V. H. Wilson

THIS paper is a description of the opera¬tion and results of a Humphreys Spiral Silt Cleaning Plant at the Powderly Colliery of The Hudson Coal Co. during the first nine months of operation and follows a pre¬liminary description given at the Anthracite Institute in May, 1947, in a paper titled "Preparation of Anthracite Sift for Boiler Fuel in a Humphreys Spiral Test Plant" by H. H. Otto, V. H. Wilson and W. L. Dennen. This plant is considered a full size operating test plant and, like all new plants, numerous minor changes in the methods of operation have been made from time to time to secure the results desired. Views of the silt preparation plant and of the screening house are given in Fig 1 and 2. This plant consists of 48 spirals in 8 batteries of 6 spirals each, 36 of which were to be operated as primary spirals and the remaining 12 as secondary spirals. A brief description of the plant and its operation follows. The only material cleaned at the plant during 1947 was that carried in the underflow from the Thickener which handles the Breaker waste water. This underflow, amounting to approximately 2000 gpm of water and containing 12.6 pct of solids, is pumped .to vibrating screens where the plus 316-in. material is removed. (Fig 3). This oversize material drops into a pocket from which it is trucked to the run-of-mine

Jan 1, 1948

By C. D. Woodward

THE Anaconda Copper Mining Co. purchases 25,000 kw. of electric power for its mining operations at Butte Mont. This power is delivered, over duplicate feeders, in the form of 60-cycle, 2400-volt, three-phase current, to five compressor plants, where most of the energy is used for driving air compressors. At the compressor plants are located the switching apparatus for controlling the 2400-volt power and distributing it to the various mines. At these points, also, there are a number of motor-generator sets for converting the alternating current to 275-volt. direct current for the haulage systems. Pole lines convey the power from the compressor plants to outdoor transformer substations at most of the mines. When it is not economical to distribute the power at the lower voltages in the mines, transformers and motor-generator sets are placed at strategic points .underground. All power is purchased on a maximum-demand basis, therefore there is installed at one of the compressor plants an eight-element totalizing graphic wattmeter. This instrument records simultaneously the value of all power taken at the numerous points of delivery, which not only eliminates the diversity factor but permits load dispatching between compressor and pumping plants, and thus materially reduces the maximum demand from the power system. As most of the mine hoisting is done, by 90-lb. compressed-air winding engines, the air-compressor equipment for the winding engines and mining operations is quite extensive. The standard air compressor has a rating of 7500 cu. ft. per min. of free air, and most of the compressors are directly connected to synchronous motors. The synchronous motors are designed for 80 per cent. leading power factor, thus facilitating power-factor correction of total mine load. Consequently by cooperation with the power company, the voltage of the power received at the compressor plants is constant.

Jan 2, 1922

By W. A. Forbes

PAGE Introductory............357 ReasoNs for Gas Cleaning.........358 First Methods of Separation of Dust.......359 Amount of Dust Produced by the Blast Furnaces of the United States Steel Corporation During 1912.....359 Dust Content in Blast-Furnace Gas.......360 Primary Cleaning. Dry Cleaning: General Remarks..........360 Braasert- Witting Whirler........362 Brassert Modifications of Brassert-Witting Whirler....363 Dyblie Whirler..........363 Remarks on Efficiency of Dry Cleaning......366 Wet Cleaning: Zschocke System..........367 Duquesne Tower..........367 Bian Gas Washer..........369 Final Cleaning. Wet Cleaning: Theisen Gas Washer.........371 Theisen Disintegrator Gas Washer.......372 Schwerz-Bayer Disintegrator Gas Washer..... 374 Fowler & Medley Vertical Gas Washer......376 Feld Gas Washer..........377 Reco Centrifugal Gas Washer........379 Sepulchre Gas Washer.........381 Dry Cleaning: Halberger-Beth Gas-Cleaning System......382 Smith.Bagley Gas-Cleaning System,......384 Howard Dust Separator.........387 Possible Separation of Dust by Electrical Precipitation ... 389 KapnOGraph............389 Methods of Determining DUst in Gas.......389 Advantages of Clean Gas.........393 Introductory. During the early stages of blast-furnace practice. the gas formed in the furnaces by the combustion of the coke used in smelting the ores was allowed to escape into the atmosphere. The light furnished

Jan 1, 1914

By W. A. Riggs

In a single year the total transportation cost equals nearly 30 pct of the value of mineral commodities, the largest single cost from the deposit to consumer. The magnitude of this economic factor calls for more complete understanding of cost and operational problems between producer and carrier than now exists. Details are given of the costs of providing transportation as well as freight rates for selling transportation. In 1958, transportation of mineral commodities in the United States required 600 billion ton-miles to move 1 3/4 billion tons of products of mines comprising solid fuels, crude oil, industrial minerals and rocks, and ores. Possibly 17 pct was handled by more than one mode of transport, since combinations of several modes of transport may, at times, achieve better service/cost results than any single mode. Total transportation cost of nearly $5 billion equaled roughly 30 pct of the value of the mineral commodities, the largest single cost from the mineral deposit to the consumer. The tremendous magnitude of this transportation undertaking demands much more complete understanding than now exists between mineral producers and carriers about the economic and operational problems of each other. A substantial portion of the daily work of the writer is spent in trying to act as a combination interpreter and catalyst between potential shippers and carriers, hoping to direct both to points of mutual understanding and advantage. For the purpose of this paper, it is necessary to ask mining people to accept some terminology and to try to appreciate the mental approach of the freight rate making people of the carriers. This paper will consider costs of providing transportation as well as freight rates for selling transportation—although these are fields of limited certainty. There are no accurate statistical breakdowns for all modes of transport and types of carriers indicating commodities, volume of traffic, distances, costs, and rates. Much information is available for railroads, and some for the regulated portions of air, motor, pipeline, and water transportation. Unregulated carriers, handling about half of the transportation of products of mines, are not required to report, and very little is known of their activities. Figures used herein are national in scope, unless otherwise indicated, and have generally been derived from Interstate Commerce Commission reports and files. Tonnage figures have been reduced to net tons of 2000 lb. The very generalized comparison of average mileage freight rate levels for various modes of transport provided by Fig. 1 affords advantageous perspective for the entire field of transportation costs. Dashed guide lines show cents per ton-mile, and dotted guide lines show percentage of first class railroad freight rate. While costs of other than railroad transportation more nearly follow constant cents per ton-mile functions, costs of railroad transportation show characteristic taper, or decrease in cents per-ton mile with increasing length of haul. This fundamental difference in cost is due largely to the fact that railroads and pipelines provide their own fully taxed roadway facilities while highway, waterway, and air carriers use government-provided tax-free roadway at no cost other than fuel, license, and certain excise taxes. Thus railroad and pipeline transportation might be said to carry heavy threshold costs in addition to those transportation costs which are directly variable with ton miles of transportation produced. The original basis of railroad freight rate structures lies in the classification of all articles of commerce into railroad class ralings ranging from 7 to 40 pct of first class (100 pct) rate level, dependent on value, hazard, loading characteristics, service requirements, and whether carload or less than carload. Classification tables and mileage-based (but arbitrarily grouped), rate scales are published as tariffs subject to approval by regulatory bodies. Used together, these determine class rates in cents per 100 lb between points in the U. S. Where local commercial or operating conditions render it advantageous for carriers to depart from

Jan 1, 1961

By Alberto J. Terrones L.

THE classical papers on contact metasomatic deposits by Lindgren on the Clifton-Morenci district,1 by Barrel1 on Marysville, Mont.,2 and by Goldschmitt on the Oslo district, Norway,3 laid the foundation for understanding of the importance of separating the metamorphic process from the subsequent metasomatic stage. Knopf4 made a big step forward by recognizing that sulfide ore minerals are invariably younger than silicates and by further stressing the importance of structural control5 ore finding. Some years later Harrison Schmitt6 fought the idea that contact metasomatic deposits are erratic, irregular, bunchy, economically marginal, and of small size, concluding that these descriptions have little factual basis. He emphasized the importance of detail mapping and careful geological study as fundamental requirements for a better understanding of these deposits. This article presents a comparative description of the structural features at the Magistral, Antamina, Morococha, Vilca, Ferrobamba, Katanga (Quibio), Tintaya, and Huarca contact deposits (Fig. 1). Further, it will describe how these structural features controlled the emplacement of the intrusives, their shape, distribution of metamorphic and metasomatic halos, and sulfide deposition in post-skarn structural channelways. Finally, the modifications introduced by a superimposed hydrothermal stage recognized at some localities will be discussed.

Jan 3, 1958

By G. T. Hahn

On the basis of the recommendation of Lovell, Vogel, and Wernick,&apos; Fry&apos;s reagent*2 was recently c) if decoration of the dislocations by carbon or nitrogen atoms is a factor in the etch pitting. Experiments were performed with samples of a commercial 1020 steel, a vacuum-melted iron (C - 10 to 15 ppm, 0 - 20 to 50 ppm, N < 2 ppm), both annealed 4 hr at 1100°C, and a zone-refined iron (C - 3 to 5 ppm, 0 - 10 ppm, N < 1 ppm ) in the as-cast condition. Saomple surfaces were prepared by grinding to 600A grit and electropolishing. Initially, effects of etching the steel with modifications of the basic Fry composition were examined. It was found that increasing the alcohol or HC1 concentratior~ retarded dislocation pitting; reducing the acid content promoted secondary pitting. Cooling the reagent and the sample did not improve the quality of the etch pits. Best results were obtained with freshly prepared reagent modified by increasing the CuC12 content to 15 g. This composition was used in subsequent experiments. Annealed samples were etched 10 to 15 sec; cold-worked samples —2 to 5 sec.

Jan 1, 1962

By Felicia F. Peng

The computer graphic routines and digital simulation program of coal cleaning circuits have been developed in the Mineral Processing Engineering Department, West Virginia University. The functions of the program include computing, tabulation and graphing of 1) washability characteristics of raw coals, 2) blending, 3) Tromp distribution curves for two washer types-- water only and dense medium, 4) predicting the functional relationship of yield and qualities of clean coal product in individual and overall coal cleaning circuits in coal preparation plant, and 5) determining the optimal clean coal yield based on the market and environmental specifications. Amdahl 470 V/7A digital computer, Tektronic 4025 graphic terminal and Tektronix 4663 digital plotter with Fortran IV are used to achieve the goals. The simulation with the aid of graphic routine program of coal cleaning circuits is a useful tool for coal preparation engineers in evaluating the feasibility of proposed flowsheets, in investigating the effect of a modification in a unit operation of an existing plant, in analyzing the off-line optimization, and in comparing the alternative circuit control strategies. The coal cleaning process simulation with graphic routine can contribute greatly to the decision making processes of preparation plant design.

Jan 1, 1983

By J. W. Halley

RIMMING steels derive their name from their action during solidifica-tion in the molds. As a result of incomplete deoxidation, gas is evolved during freezing, and the metal has a characteristic rolling action. The metal rises along the mold walls and descends in the center of the ingot. This action keeps the top of the ingot open and the advancing rim of solid metal can be seen. The rim grows until the rolling action is insufficient to prevent the top of the ingot from freezing or until the action is stopped by capping the ingot with a heavy plate. The violence of the reaction and its characteristics, such as growth or drop ill the molds, are deter-mined by the Composition, the furnace practice, and the deoxidation in the ladle and in the molds. Though rimming steels represent a large proportion of the amount of plain carbon steel made, they have received comparatively little attention in the technical literature. The manufacture of rimming steels has been described by Hibbard,1,2 Fleming,3 Pierce4 and Jackson.5 The reactions occurring during rimming have been considered from the theoretical point of view by Chipman and Samarin.7 The structure of rimmed-steel ingots has been discussed by Nead and one of the present authors.6 Meyer,8 in studying segregation, investigated the distribution of carbon, sulphur and phosphorus in rimmed-steel ingots by analyzing the rim and core of blooms. In their studies of segregation, the Joint Committee of the Iron and Steel Institute and the British Iron and Steel Federations studied distribution in one billet and one ingot of rimmed steel. A detailed study of the distribution throughout the ingot has not been published. The present investigation was undertaken to determine accu-rately the distribution of carbon, manganese and sulphur in normal rimmed ingots and the general distribution of other common elements present. The study included some work on the effect of pouring condi-tions and furnace practice on the distribution, though there is still much to be done in this direction.

Jan 1, 1938

By E. G. Leonardon, C. Schlumberger, M. Schlumberger

Since the beginning of the year 1928 the senior authors and their associates have applied a series of procedures which makes possible the detailed study in situ of the formations traversed by a drill hole before the casing has been landed. They have given the name "electrical coring" to the ensemble of these processes, which now replace in a large measure the mechanical coring performed by the drillers, and permit the gathering of bottom-hole data hitherto unobtainable. Three years have elapsed since the technique and interpretation of these measurements emerged from the experimental stage and entered the field of industrial application on a large scale. The total length of drill holes so far surveyed by the authors and their associates, all over the world, amounts to several millions of feet. Practical and strongly built equipment has been evolved, which permits the examination in a short time of an open hole several thousand feet long. No comprehensive paper has yet been published discussing the essential principles of the processes applied and bringing into evidence their economic interest. This is the object of the present paper.&apos; Numerous examples of field work performed under varied geological conditions are given, constituting a concrete illustration of the services rendered by the new methods. The study in situ of the formations penetrated by a drill hole is based on the measurement of a given physical factor or parameter associated with these formations. Generally the measurements are made systematically along the whole length of the open hole. The physical factors , or parameters which are now utilized by us to this end are: (1) the resistivities of the rocks; (2) their porosity; (3) their electrical anisotropy; (4) their temperature; (5) the resistivity of the muds. In order to

Jan 1, 1934

By William H. Shockley

Though China has been widely explored by mining engineers during the past dozen years, comparatively little has been published concerning its mineral resources. The few moilographs scattered through the transactions of various societies contain far less information than the private reports made to the numerous syndicates which have sent out engineers. The best general account of the geolopy and mineral resources of China is to be found in the works of von Richthofen,&apos; a remarkably gifted observer. The observations recorded here in this paper were made in the service of the Pekin Syndicate (which has kindly given me permission to publish them), during the first months of 1898, among the coal- and iron-fields of southeastern Shansi. This is one of the largest anthracite-regions known, the area being

Jan 1, 1904

By T. Egleston

DURING the year 1873, my attention was called to the frequent accidents, resulting from the breaking of rails, on the different railroads in this country, and I was requested to investigate the subject. The plan of investigation I proposed was to ascertain, in as many cases as possible, the exact history of broken rails, both in this country and in Europe; to collect information in Europe relating to the tests which rails used there were required to undergo, and to experiment upon the pieces of rails broken on the road, with a view to ascertain whether their fracture was due to their chemical constitution, bad manufacture, to a reduction in strength owing to temperature, or to physical changes in the constitution of the rail. The investigation was commenced by the collection of statistics, and for this purpose I spent several months in Europe, collecting information on the subject of broken rails, as well as the life of iron and steel rails generally, and inquiring into the systems of purchasing and of testing them employed by the railroads there, intending, on my return, to make a series of analyses of rails broken, both in this country and in Europe; to ascertain, if possible, how far great cold had an influence on the fracture ; to examine whether the rail broken, either on the road or afterwards, underwent, at or about the fracture, any physical change, and to make a series of experiments on the strength of rails manufactured in the United States or sold in the American market. Unfortunately, the panic of 1873 came on, just before my return from Europe, and prevented the carrying out of the larger part of the plan proposed ; as, however, I had collected in the meantime, a large number of statistics of different kinds from all parts of Europe, and had made a number of interesting experiments and investigations, I have thought it would be worth while to communicate some

Jan 1, 1875

By E. Miller, J. M. Eldridge, K. L. Komarek

Activities of magnesium in liquid Mg-Sn alloys have been determined between 5 and 90 at. pct Sn and 990" and 1290°K by an improved isopiestic method wherein tin specimens, heated in a temperature gradient and contained in crucibles of special geometry, were equilibrated with magnesium vapor in a closed titanium system. The crucibles were designed so that the equilibrium compositions of the specimens were satisfactorily preserved on termination of the experimental runs by quenching. The activity values are in excellent agreement with those predicated on the phase diagram and allowed a delineation of the solidus curve of the compound Mg2Sn near its melting point. EQUATIONS have been recently derived relating the chemical potentials of the components to the liquidus and enthalpy data for binary systems exhibiting one congruently melting compound.&apos; The liquidus curve of the Mg-Sn system between the eutectics was carefully redetermined and the thermodynamic properties thus calculated were in reasonably good agreement with values derived from electromotive-force measurements of an,&apos; but differed greatly from the iso-piestically determined values of Ashtakala and Pid-geon.3 The present study was initiated: a) to resolve the discrepancies; b) to develop a method for measuring activities in systems having volatile (and possibly highly reactive) components; and c) to use the method in a general investigation of the thermodynamic properties of the homologous series of Mg-Group IVb systems, i.e., Mg-Pb, Mg-Sn, Mg-Ge, and Mg-Si. This paper describes the results for the Mg-Sn system. An isopiestic technique, originally developed by Herasymenko 4 and adapted for alloys having a component of high reactivity and low volatility,5-8 was modified in this study by using crucibles designed to preserve the equilibrium composition of highly volatile liquid specimens on quenching from high temperatures. Tin specimens, contained in tightly covered graphite crucibles and heated in a temperature gradient, were equilibrated with magnesium vapor of fixed pressure from a magnesium reservoir kept at constant temperature in a previously evacuated and sealed titanium tube. During equilibration magne-

Jan 1, 1967

[Cyanidation: Fresnillo, Mexico. 112. 734, 739. Abs.. YB84. 34 gold ore: before or after amalgamation. respective merita. 118, 538 high residue avoided by milling in water, 118, 542 Homestake mill, 112,607. 614 impoverishing gold ore before cyanidation justified. 118, 539 Kirkland Lake district, 112, 648, 649. Abs., YB84.32 literature prior to 1932. See Source Book. McIntyre Porcupine mines, 118, 638 mercury as an aid to extraction of gold, 118, 53 8]

Jan 1, 1936

By Theo B. Comstock

Since 1892 the writer has published several articles in the Engineering and Mining Journal concerning the relations of the

Jan 1, 1901

By Walter Herd

Fox the past eight years No. 2 mine of the Cumberland Railway & Coal Co., Springhill, Nova Scotia-a subsidiary of the Dominion Coal Co., Ltd.-has had an unenviable reputation for bumps. As the workings extended in certain directions under a greater cover, these bumps increased in severity and it became apparent that some change in the system of extraction was necessary if the mine was to continue to operate. In September, 1924, following several fatalities resulting from bumps, the Mines Department of Nova Scotia requested from the U. S. Bureau of Mines the services of George S. Rice, Chief Mining Engineer of the Bureau, to report on the conditions then prevalent in No. 2 mine, Springhill. This request was promptly and courteously granted. Mr. Rice made a full investigation and a comprehensive and helpful report, which is embodied in the 1924 Annual Report of the Department of -Public Works and Mines, Nova Scotia. Prior to 1925, the room and pillar method was employed and in January of that year (there being a cessation of work from March to August due to labor troubles) longwall retreating on the west side, on a limited scale, and in a small section on the east side of the mine was started. The major portion of the east side was not operated on this system till August, 1926, as there was developed a considerable area ready for pillar extraction between an arbitrary boundary and a point up to which bumps of any consequence, had not been experienced. In the interval development work for longwall retreating below the 5900-ft. level was vigorously- pushed. This longwall retreating system was suggested by Mr. Rice as a possible remedy and was heartily endorsed by the company officials. This paper describes the conditions and happenings subsequent to Mr. Rice&apos;s report and more especially the results with the longwall retreating system of mining under the peculiar circumstances pertaining to mining. No. 2 Seam, Springhill, at depth, and records the &apos;conclusions which experience with several severe bumps under this mode of extraction would suggest. Except where necessary to make the paper intelligible as an entity any duplication of Mr. Rice&apos;s report will be avoided.

Jan 1, 1929

By E. C. Harder

INTRODUCTION THE situation in the United States, at the present time, regarding the supply of manganese ores and alloys of manganese is one of great seriousness and is likely to become increasingly so while the European war continues. The two principal iron-manganese alloys, ferromanganese and spiegeleisen, are indispensable in steel manufacture, being used extensively in the Bessemer and openhearth processes.. Spiegeleisen, the lower alloy, contains between 15 and 25 per cent., and ferromanganese, the higher alloy, between 60 and 80 per cent., of manganese. Besides manganese the alloys contain iron and carbon. On the market ferromanganese is usually quoted on the basis of 80 per cent. manganese, and spiegeleisen on the basis of 20 per cent. manganese. The consumption of ferromanganese has been increasing during recent years at the expense of spiegeleisen, because larger quantities of the latter must be used to ac-complish the same purpose with the result that the amount of carbon introduced with it into the molten metal is frequently injuriously great. Manganese ore proper, in the form of manganese dioxide, is used extensively in many chemical industries, especially for oxidizing purposes. It is also used for the manufacture of both wet and dry electric cells and in the manufacture of paints and dyes. The manganese ore used in this country has been derived hitherto from three principal sources:. Southern Russia, Southern British India and East Central Brazil. The following tables show the quantity of manganese ore imported from these countries, and (for comparison) the domestic production, during 1912, 1913 and 1914. The imported manganese ore has been used largely in the manufacture of iron-manganese alloys and in addition large quantities of the alloys themselves have been imported, chiefly. from Great Britain, Germany and other European countries.

Jan 5, 1916