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By R. H. B. Jones

This paper reviews pertinent geology of the Biwabik iron formation, Mesabi Range, Minnesota. This iron formation is divisible into four members. Each member is distinctive and contains marker horizons, which are recog nizable throughout all phases of alteration from lean, fresh rock to high-grade iron ore. Some beds have a larger magnetite content than others. During the process of ore genesis, which is essentially an oxidation process, the magnetite content is lowered. Alteration from iron formation to ore includes both oxidation of iron minerals and silica removal by leaching and these distinct processes progress at variable rates for different locations and structures. Magnetic intensities, of each horizon of the iron formation are dependent chiefly upon its preoxidation magnetite content, upon the subsequent degree of oxidation, upon the character of the enclosing rocks, and on the extent of fracturing, folding, or faulting. The results of a number of magnetic surveys are described and are correlated with results of drill-hole and mine exploration and developmerit. The magnetic anomalies obtained are discussed in relation to phases of formation of ore within the iron formation. General Information One hundred years ago a party of surveyors, applying the principles of geophysical prospecting, discovered iron ore in the state of Michigan in the Lake Superior district. This event was officially reported as follows:' On Sept. 19 (1844) while running the east line of Town 47 North, Range 27 West, they observed by means of the solar compass remarkable variations in the direction of the needle, amounting to 87" from the normal. Ascribing this phenomenon to iron ore, they sought and found it in ledges or outcrops at several points. The solar compass referred to was invented by William A. Burt, deputy surveyor in charge of this party.2 It is used for determining the true meridian by an observation on the sun. Eight years later, on July 7, 1852, the first iron 're, consisting of 6 bbl. of Ore, was shipped from Marquette, Michigan. It was another 40 years before the first or> shipment left the Mesabi Range in Minnesota, in October 1892. It totaled 4245 tons. Fifty years later, 90 years after the original shipment, during 1942 the Lake Superior district shipped 93,495,392 gross tons of iron ore. Production came from Minnesota, Michigan, Wisconsin, and Ontario, Canada. Throughout the 90-Year period it was known that magnetic properties of most of the ore bodies, and of the iron formations in which they occur, affected the compass. This phenomenon, later to be made use of to outline areas of ground favorable for exploration, was at first a

Jan 1, 1949

By R. H. B. Jones

This paper reviews pertinent geology of the Biwabik iron formation, Mesabi Range, Minnesota. This iron formation is divisible into four members. Each member is distinctive and contains marker horizons, which are recog nizable throughout all phases of alteration from lean, fresh rock to high-grade iron ore. Some beds have a larger magnetite content than others. During the process of ore genesis, which is essentially an oxidation process, the magnetite content is lowered. Alteration from iron formation to ore includes both oxidation of iron minerals and silica removal by leaching and these distinct processes progress at variable rates for different locations and structures. Magnetic intensities, of each horizon of the iron formation are dependent chiefly upon its preoxidation magnetite content, upon the subsequent degree of oxidation, upon the character of the enclosing rocks, and on the extent of fracturing, folding, or faulting. The results of a number of magnetic surveys are described and are correlated with results of drill-hole and mine exploration and developmerit. The magnetic anomalies obtained are discussed in relation to phases of formation of ore within the iron formation. General Information One hundred years ago a party of surveyors, applying the principles of geophysical prospecting, discovered iron ore in the state of Michigan in the Lake Superior district. This event was officially reported as follows:' On Sept. 19 (1844) while running the east line of Town 47 North, Range 27 West, they observed by means of the solar compass remarkable variations in the direction of the needle, amounting to 87" from the normal. Ascribing this phenomenon to iron ore, they sought and found it in ledges or outcrops at several points. The solar compass referred to was invented by William A. Burt, deputy surveyor in charge of this party.2 It is used for determining the true meridian by an observation on the sun. Eight years later, on July 7, 1852, the first iron 're, consisting of 6 bbl. of Ore, was shipped from Marquette, Michigan. It was another 40 years before the first or> shipment left the Mesabi Range in Minnesota, in October 1892. It totaled 4245 tons. Fifty years later, 90 years after the original shipment, during 1942 the Lake Superior district shipped 93,495,392 gross tons of iron ore. Production came from Minnesota, Michigan, Wisconsin, and Ontario, Canada. Throughout the 90-Year period it was known that magnetic properties of most of the ore bodies, and of the iron formations in which they occur, affected the compass. This phenomenon, later to be made use of to outline areas of ground favorable for exploration, was at first a

Jan 1, 1949

By T. B. Counselman

PROBABLY the earliest concentration of iron ore in this country was carried on in the northeastern magnetite areas. Magnetic concentration was relatively simple and gave a concentrate that, after agglomeration, and in spite of being high in phosphorus because of the dry concentrating methods then in use, was satisfactory blast-furnace feed. Production from the northeastern magnetite area languished after the discovery and development of the Lake Superior ores, where there was seemingly an unlimited tonnage of high-grade ore, first the Michigan ores, and subsequently the still larger deposits of Minnesota. For years only the higher grade, direct shipping ores of the Lake Superior district were mined. Those of Michigan, and of the Vermilion Range in Minnesota, were hard ores and came principally from underground mines. The softer ores of the Mesabi came partly from underground mines, but mostly from the enormous deposits that could be worked by open-pit methods. The costs of ore from these open-pit deposits, even with the high initial cost of stripping, were so low that the underground mines of the Mesabi could hardly compete. The so-called Old Range ores, of Michigan and of the Vermilion Range of Minnesota, were hard and lumpy, and opened up the burden in the blast furnace, therefore making possible harder driving with greater output. Also, some of these ores were of such grade and physical characteristics that they were suitable for charge ore in the open hearth. These ores, therefore, commanded a price premium, and could compete with the softer, finer, but cheaper, Mesabi ores. The big tonnage reserves, however, are on the Mesabi, and it is these big open-pit deposits that constitute our stock pile of iron ore, from which we are drawing so heavily during this war period. On the western end of the Mesabi the ore was found to be high in silica, and not suitable as furnace feed. As early as 1902, attempts were made to concentrate this so-called wash ore and by 1910 the first washing plant was put into operation. The process was very simple, consisting essentially of a sizing and washing operation, with scalping screens, logwashers, and tables, which later were replaced by classifiers. Ore particles finer than 100 mesh were deliberately wasted, because these fines were undesirable in the furnace. Fortunately, these tailings were impounded, and already are being reworked. Before long some of the low-grade ores began to require more elaborate treatment than the simple washing operation and, tables having been discarded because of their low capacity, in favor of classifiers, jigs were next introduced. These were able to discard coarser pieces of tailing than classifiers. Jigs are in active use today, various improvements having been made in their design and application. Various other machines and methods of concentration have been tried from time to time, and have in turn been discarded for more improved processes. The latest and most important process that has been

Jan 1, 1943

By K. D. Jacob

MONTANA Phosphate Produucts Co., a subsidiary of The Consolidated Mining and Smelting Co. of Canada Ltd., operates three properties near Garrison, Mont., known as the Anderson, Graveley, and Luke mines. All three are underground operations, mining the same narrow bed at points several miles apart. The Anderson, the oldest and largest of the three, has produced about 700,000 long tons since 1929. The Graveley has produced slightly over 100,000 long tons since 1940, and the Luke, acquired in 1943, is still in an early stage of development. The great bulk of the output has been shipped to the Trail, B. C., plant of Consolidated Mining and Smelting Co. for use in the manufacture of fertilizers. The phosphate seam is the basal member of the Permian Phosphoria formation. In all three mines it has a uniform thickness of 3 to 4 ft. of oulitic phosphate, with a few shaly partings. The overlying part of the formation comprises about 50 ft. of chert and the immediate footwall consists of a few feet of shale and sandstone. underlain by the Quadrant quartzite.

Jan 1, 1944

By Horace W. Hindry

This paper presents the ingredients composing a type of oil-base mud that has been successfully used in drilling oil horizons in California, the effect of ingredient concentrations on physical properties, methods of handling at the well and possible advantages of a waterless drilling fluid with excellent plastering properties. INTRODUCTION AN oil-base mud is a rotary drilling fluid in which oil has been substituted for water as the principal liquid ingredient. In recent years such a mud has been developed and used successfully for drilling the oil horizons of wells in various California fields. There are several types of oil-base mud, but only the type that is currently used to any appreciable extent will be considered at this time. The oil-base drilling-mud compositions used by Shell Oil Company, Incorporated have been covered by several patent applications on which patents are expected to issue at an early date. The purpose of this paper is to present data on the fundamental design of the mud; the ingredients used and their specifications; the effect of ingredient concentration on physical properties; the selection of the proper mud; the facilities needed for handling the mud; and a general discussion [oil] drilling with oil-base mud. In view of the early stage of development of oil-base mud, the great number of variables, and the almost unlimited possible combinations of these variables, which in turn require extensive laboratory study, there are certain irregularities and omissions in the data presented here. However, it is believed that sufficient data are at hand to permit a fairly complete analysis of the characteristics of oil-base muds. In view of the excellent plastering properties of oil-base mud when properly proportioned, its use should: (I) minimize the possibility of impairing the natural flow potentialities of the producing horizon such as that resulting from infiltration of water from water-base muds; (2) permit smaller clearances for setting liners, since the mud sheath has no appreciable thickness; (3) eliminate the possibility of clogging the perforations of the liner with thick mud sheath; (4) facilitate the removal of the mud sheath from the walls of the hole, for its mud sheath has no appreciable strength; (5) assist in drilling through formations, such as "heaving shale," where water wetting appears to be a source of difficulty. (6) permit cores to be obtained without contamination from drilling water. FUNDAMENTAL DESIGN OF AN OIL-BASE MUD In the design of any rotary drilling mud it is necessary to select materials that will fulfill the following requirements: (I) act as the liquid medium and regulate the viscosity; (2) impart initial and final plastering properties; (3) give gel strength and structure in order to prevent settling; (4) serve as a weighting material. The

Jan 1, 1941

By William Mikulas

LITTLE work has been done in the field of the nickel-tin binary system. The complete diagram has been investigated on two occasions, but the results are in very poor agreement. The structure of a compound NiSn, and the solubility of tin in nickel have been determined by X-ray methods. Several investigations have been made of the liquidus curve, and the compositions of the eutectics have been determined. A study of the literature, however, shows that there is no satisfactory agreement between the data presented in the various papers. The present investigation was undertaken in an attempt to determine the equilibrium conditions, and to correlate X-ray with metallographic data. The equilibrium diagram was determined by thermal and metallo-graphic means, and the solubility of tin in nickel further investigated with X-rays. Powder diagrams were made of the intermetallic com-pounds, and three of the structures were partly determined. No attempt was made to determine the range of homogeneity of the inter-metallic compounds.

Jan 1, 1937

By K. D. Jacob

IN the decreasing order of the tonnages involved, the uses of phosphates can be grouped conveniently into three general classes, namely, fertilizer; chemicals for military, industrial, and technical purposes; and mineral feed for livestock. The quantity of phosphate used as fertilizer, principally in the form of superphosphate, has always exceeded by far that used for all other purposes, though in recent years a marked increase has occurred in its consumption for the other two general classes of uses. Prior to the present century large quantities of superphosphate, as well as a considerable portion of the production of phosphorus chemicals, score made from bone materials which were plentiful and cheap in some areas and which could be more easily processed than phosphate rock for the manufacture of chemicals. Today, however phosphate rock has almost completely displaced bone as a raw material for the manufacture of chemically processed phosphates in nearly all countries of the world.

Jan 1, 1944

By Henderson, Robert

A GOOD idea of the magnitude of the underground operations at Climax can be gained from the following figures. A little more than 43,000,000 tons has been drawn from the mine and of this amount, 40,500,000 tons has been drawn in the past ten years and 12,000,000 tons was drawn in two of the war years. The maximum daily average output over a period of one month was slightly more than 20,000 tons but during this period, production on certain days was 24,000 tons, and 9000 tons was produced in a single eight-hour shift. This production came chiefly from 260 draw points although all of them were never in operation at one time. The haulage system for these draw points is made up of 7.5 miles of 36-in.-gauge track, and 131,000 ft. of subsidiary drifts and 44,000 ft. of raises have been driven to develop the necessary broken ore reserves for this high production. Power consumption is often considered an index of operating efficiency. In 1943, the year of maximum production, the mine power consumption was 19,223,000 kw.-hr. or 3 kw.-hr. per ton; in 1945 it was 3.5 kw.-hr. per ton. To handle this amount of power, there are four transformer stations and one switch station in the mine. Mr. Garrabrant, the chief electrician, describes the electrical installation in this issue.

Jan 1, 1946

By L. E. Young

GERMANY'S recent collapse and the occupation by the Allies of the coal fields of the Ruhr, the Saar, Silesia, Poland, and Czechoslovakia have focused attention on the postwar coal problems of Europe. American coal operators are interested deeply in what is happening in Britain, particularly in the discussion of plans to rehabilitate and reorganize the entire British coal mining industry, as such reorganization will probably determine the place Britain will occupy in the European coal markets for the next few decades. The continuing decline of British out-ut per man-shift, particularly during wartime, has resulted in a most serious effort to determine whether this unfortunate trend is due to the physical condition of the coal seams, poor management, poor engineering and planning, inadequate use of power and machinery, or failure of labor to co-operate with management.

Jan 1, 1945

By Emery R. Hayhurst

SILICOSIS has been described in a report of the American Public Health Association as a disease due to breathing air containing silica, characterized anatomically by generalized fibrotic changes and the development of miliary nodulations in both lungs, and clinically by shortness of breath, decreased chest expansion, lessened capacity for work, absence of fever, increased susceptibility to tuberculosis (some or all of which symptoms may be present), and by characteristic X-ray findings. ... The disease is divided arbitrarily into first, second, and third stages for convenience of description and possible compensation purposes. At least two distinct types of silicosis are recognized, acute and chronic. The acute form was reported as early as 1713, when a British patent for grinding flint by wet methods was granted because the dry powdered material "proved very destructive to mankind, so much that any person, ever so healthful, working in that business cannot possibly survive over two years."

Jan 1, 1936

By P. R. Bradley

NO thought had been given to deep level mining at the Alaska Juneau mine prior to 1930, but in that year a prospect winze was started and continued for 1000 ft. vertically below the main haulage or adit level. The point at which this winze was started was selected entirely by the prevailing physical conditions, such as proximity to established workings, convenience, and the presence overhead of a substantial pillar of dimensions sufficient to lo¬cate the sheave wheel and loading pocket. It was, therefore, with some surprise that the unusually high-grade ore found just below the collar of the winze persisted, with certain vari¬ations, to a full depth of 1000 ft. vertically. Likewise this unusually high-grade ore was found to persist on the various crosscuts driven on levels at 200-ft. vertical intervals. To be brief, this deep level work found richer ore than any yet found in the mine over like areas, and inasmuch as the area was sufficient to plan for extensive deep level mining, plans for such work were given extended consideration.

Jan 1, 1936

By B. M. Burchfiel

CALIFORNIA possesses such an abundance of ceramic materials other than clays, that she is quite independent of other states and foreign countries so far as these materials are concerned. Certain users import some feldspar, silica, and allied minerals, but they do so from choice and not necessity. Production is largely for home consumption, so the total volume of ceramic materials produced is comparatively small. Many small deposits of the materials here under discussion are worked by individuals, and their output sold to individual grinding companies or users. The data given here shall be confined to the larger deposits and developments because they give a truer picture of typical deposits, operations, and materials.

Jan 1, 1936

By H.E. Brauer

Among the zinc base alloys used for casting in metal moulds, pnrticularly die casting, those alloys containing aluminum usually together with copper, are probably the most widely used. The reason lies in their desirable mechanical properties and the fluidity and absence of hot shortncss which facilitate ca,sting. Objection to the use of these alloys may be raised on account of the rather frequent instances of failure of a type variously described as disintegration, exfoliation and intererystalline corrosion. In all cases which have come to our kno~vlcdge where the conditionsof service were known, failure has occurred upon cxposurc to moisture and heat varying from a hot moist atmosphere to lligh pressure steam. RIoreover, the alloys described in all such roses contain impurities or alloying metals which the present authors have found to have enormous accelerating effects on intererystalline oxid:~t'ion in zinc-aluminurn alloys. Thus Williams1 experimented with an alloy containing a large percentage of tin exposed in Cuba. Baucr2 reports failure of a boiler plug containing over 1 per cent. of impurities, doubtless lead for the must part, and Rawdon's3 examinations were madc on an alloy containing 0.1 per cent. lead also exyosctl to thc Tropics. No thorough investigation of the nature and cause of this type of failure has been made heretofore, so far as the authors are aware, although Rawdon correctly classified it as internal oxidation. We have, therefore, carried out this investigation in order to det'ermine the exact nature of this phenonienon and the effect of other metals present as impurities or intentional additions in accelerating or retarding it. In the appendix we include a considerable amount of data which may be valuable in selecting an alloy combining good physical properties with high resistance to oxidation. At the time this work was undertaken the best available equilibrium *Investigator, Metal Section, Research Division, The New Jersey Zinc Company. 'H. W. Williams—Jour. Am. Inst. of AIet,als, Vol. 11, p. 221 (1917). 2o. Bauer—ZeiL, fiir i'vletall Kunde, Vol. 12, .No. 7, pp. 129-31 (1920). 3H. S. Rawdon—Trans. Am. Elcctrochcmic.al Society (1921).

Jan 1, 1923

By H. E. Brauer

Among the zinc base alloys used for casting in metal moulds, pnrticularly die casting, those alloys containing aluminum usually together with copper, are probably the most widely used. The reason lies in their desirable mechanical properties and the fluidity and absence of hot shortncss which facilitate ca,sting. Objection to the use of these alloys may be raised on account of the rather frequent instances of failure of a type variously described as disintegration, exfoliation and intererystalline corrosion. In all cases which have come to our kno~vlcdge where the conditionsof service were known, failure has occurred upon cxposurc to moisture and heat varying from a hot moist atmosphere to lligh pressure steam. RIoreover, the alloys described in all such roses contain impurities or alloying metals which the present authors have found to have enormous accelerating effects on intererystalline oxid:~t'ion in zinc-aluminurn alloys. Thus Williams1 experimented with an alloy containing a large percentage of tin exposed in Cuba. Baucr2 reports failure of a boiler plug containing over 1 per cent. of impurities, doubtless lead for the must part, and Rawdon's3 examinations were madc on an alloy containing 0.1 per cent. lead also exyosctl to thc Tropics. No thorough investigation of the nature and cause of this type of failure has been made heretofore, so far as the authors are aware, although Rawdon correctly classified it as internal oxidation. We have, therefore, carried out this investigation in order to det'ermine the exact nature of this phenonienon and the effect of other metals present as impurities or intentional additions in accelerating or retarding it. In the appendix we include a considerable amount of data which may be valuable in selecting an alloy combining good physical properties with high resistance to oxidation. At the time this work was undertaken the best available equilibrium *Investigator, Metal Section, Research Division, The New Jersey Zinc Company. 'H. W. Williams—Jour. Am. Inst. of AIet,als, Vol. 11, p. 221 (1917). 2o. Bauer—ZeiL, fiir i'vletall Kunde, Vol. 12, .No. 7, pp. 129-31 (1920). 3H. S. Rawdon—Trans. Am. Elcctrochcmic.al Society (1921).

Jan 1, 1923

L. D. GODSHALL, Everett, Washington: This very interesting paper cannot fail to command the attention of every one who has ever had experience in the amalgamation of gold-ores. I wish to call attention to three very important facts brought out very prominently by the paper, namely: 1. The extent of accumulation of amalgam on copper plates in the form of scale, not removable in the ordinary manner; 2. The change in the relative quantity of the two metals in the amalgam as we. recede from the battery-discharge; 3. The difference in fineness of the bullion obtained from the above-mentioned scale as compared with the bullion from the daily clean-ups. From Mr. Bayliss's figures we find that during the life of the plate in question 14,942 tons of ore were crushed, yielding amalgam of the value of $5.03 per ton, or a total value of $75,158.26. The amalgam accumulating on the plate during this time as scale, we find to have had a value of $8340.54, or $0.558 per ton of ore treated, representing 11.09 per cent. of the total amount of amalgam saved in the ordinary clean-up; or, taking the amalgam saved by daily clean-up plus the amalgam-scale as representing the total saved on this plate, or 100 per cent., we find that the daily clean-up saved 90.01 per cent., while the scale represented 9.99 per cent. The above figures do not include some additional amalgam still adhering to the plate after scale had been removed. We are told that this was not an exceptional case at the Drum Lummon, but that other plates have even yielded a third more than the one in question. The interesting query now comes up, whether this experience at the Drum Lummon is exceptional or universal at all mills; and another question arises, as to how long such an accumulation might continue,

Jan 1, 1897

Carlisle: Jim Knapp, has been the good friend of hundreds-maybe thousands-of mining men in these western states in the last 40 or 50 years. Jim is going to talk about many of the mining camps of Nevada, where he has done plenty in the mining field during the last 50 years. Jim, for a starter, how did you happen to go to Nevada? Knapp: In the summer of 1902, two years after the discovery at Tonopah, the professor of mining at Stanford sent out myself and another student by the name of Joe Miller to make a report on the camp. We left San Francisco at 8 p.m., got to Reno the next morning, then took the train to Sodaville, arriving about 4:30 in the afternoon. The first man I met when I arrived at the Tonopah station was Tasker Oddie, a gentleman who later became the Govenor of the State and then a United States Senator. Before we got away from the stage station I also met S. H. Brady, the first mining engineer to put out his shingle in Tonopah. He afterwards became general manager of the West End Mining Co.

Jan 3, 1965

By Frederic Brunton

I. INTRODUCTION THE smelting plant of the British Columbia Copper Co. at Greenwood, B. C., now closed because of the decline in the price of copper due to the European war, is of special interest to metallurgists for several reasons. It was successfully smelting in blast furnaces the lowest grade copper ore of all plants in America. In order to do so, it had to run at' very high efficiency, which necessarily required a large tonnage per square foot of hearth area, together with the minimum amount of labor and other costs. The furnaces smelted daily 2,250 tons of ore (6.62 tons per sq. ft. of hearth area), carrying 0.85 per cent. of copper, at a smelting cost of $1.18 per ton. The entire plant required 130 men to operate it and keep up repairs, showing a labor efficiency of about 17.5 tons per man per day. In the present paper, the method of obtaining these results is shown. Most of the information contained in this description I obtained as Assistant Superintendent, during the two years preceding the present shutdown. Other sources of information to which I am indebted are: The British Columbia Copper Co., Ltd., by Alfred W. G. Wilson, in The Copper Smelting Industry of Canada; Greenwood Smelting Works, by J. E. McAllister, Engineering and Mining Journal, vol. xci, pp. 1011 to 1015 (May 20, 1911); and Description of the Copper Smelter of The British Columbia Copper Co., by W. L. Bell, in Transactions of the Canadian Mining Institute, vol. xvi, pp. 151 to 154 (1913).

Jan 7, 1915

By T. B. Counselman

PRobably the earliest concentration of iron ore in this country was carried on in the northeastern magnetite areas. Magnetic concentration was relatively simple and gave a concentrate that, after agglomeration, and in spite of beillg high in phosphorus hecause of the dry concentrating methods then in use, was satisfactory blast-furnace feed. Production from the northeastern magnetitc area languished after the discovery and development of the Lake Superior ores, where there was seemingly an unlimited tonnage of high-grade ore, first the Michigan ores, and subsequently the still larger deposits of Minnesota. For years only the higher grade, direct shipping ores of the Lake superior district were mined. Those of Michigan, and of the Vermilion Range in Minnesota, were hard ores and came principally from underground mines. The softer ores of the Mesabi came partly from underground mincs, but mostly from the enormous deposits that could be worked by open-pit methods. The costs of ore from these open-pit deposits, even with the high initial cost of stripping, were so low that the underground mines of the Mesabi could hardly compete. The so-called Old Range ores, of Michigan and of the Vermilion Range of Minnesota, were hard and lumpy, and opened UP the burden in the blast furnace, therefore making possible harder driving with greater output. Also, some of these Ores were of such grade and physical characteristics that they were suitable for charge ore in the open hearth. These ores, therefore, commanded a price premium. and could compete with the softer, finer, but cheaper, Mesabi ores. The big tonnage reserves, however, are on the Mesabi. and it is these big open-pit deposits that contitue- our stock pile of iron ore, from which we are drawing so heavily during this war period. On the western end of the Mesabi the ore was found to be high in silica, and not suitable as furnace feed. As early as 1902, attempts were made to concentrate this so-called wash ore and by 1910 the first washing plant was put into operation. The Process was very simple, consisting essentially of a sizing and washing operation, with scalping screens, logwashers and tables, which later were replaced by classificrs. Ore particles finer than I00 mesh were deliberately wasted, because these fines were undesirable in the furnace. Fortunately, these tailings were impounded, and already are being reworked. Before long some of the low-grade ores began to require more elaborate treatment than the simple washing operation and, tables having been discarded because of their low capacity, in favor of classifiers, jigs were next introduced. These were able to discard coarser pieces of tailing than classifiers. Jigs are in active use today, various improvements having been made in their design and application. Various other machines and methods of concentration have been tried from time to time, and have in turn been discarded for more improved processes., The latest and most important process that has been 38

Jan 1, 1944

By T. B. Counselman

PRobably the earliest concentration of iron ore in this country was carried on in the northeastern magnetite areas. Magnetic concentration was relatively simple and gave a concentrate that, after agglomeration, and in spite of beillg high in phosphorus hecause of the dry concentrating methods then in use, was satisfactory blast-furnace feed. Production from the northeastern magnetitc area languished after the discovery and development of the Lake Superior ores, where there was seemingly an unlimited tonnage of high-grade ore, first the Michigan ores, and subsequently the still larger deposits of Minnesota. For years only the higher grade, direct shipping ores of the Lake superior district were mined. Those of Michigan, and of the Vermilion Range in Minnesota, were hard ores and came principally from underground mines. The softer ores of the Mesabi came partly from underground mincs, but mostly from the enormous deposits that could be worked by open-pit methods. The costs of ore from these open-pit deposits, even with the high initial cost of stripping, were so low that the underground mines of the Mesabi could hardly compete. The so-called Old Range ores, of Michigan and of the Vermilion Range of Minnesota, were hard and lumpy, and opened UP the burden in the blast furnace, therefore making possible harder driving with greater output. Also, some of these Ores were of such grade and physical characteristics that they were suitable for charge ore in the open hearth. These ores, therefore, commanded a price premium. and could compete with the softer, finer, but cheaper, Mesabi ores. The big tonnage reserves, however, are on the Mesabi. and it is these big open-pit deposits that contitue- our stock pile of iron ore, from which we are drawing so heavily during this war period. On the western end of the Mesabi the ore was found to be high in silica, and not suitable as furnace feed. As early as 1902, attempts were made to concentrate this so-called wash ore and by 1910 the first washing plant was put into operation. The Process was very simple, consisting essentially of a sizing and washing operation, with scalping screens, logwashers and tables, which later were replaced by classificrs. Ore particles finer than I00 mesh were deliberately wasted, because these fines were undesirable in the furnace. Fortunately, these tailings were impounded, and already are being reworked. Before long some of the low-grade ores began to require more elaborate treatment than the simple washing operation and, tables having been discarded because of their low capacity, in favor of classifiers, jigs were next introduced. These were able to discard coarser pieces of tailing than classifiers. Jigs are in active use today, various improvements having been made in their design and application. Various other machines and methods of concentration have been tried from time to time, and have in turn been discarded for more improved processes., The latest and most important process that has been 38

Jan 1, 1944

By Henry D. Hibbard

THIS article aims to clarify the use of some terms often occurring in writings on iron and -steel, and also to suggest several new short abbreviated names for some of the things related to the subject which now are indicated by phrases. Crude or Crude Iron The name crude or crude iron is recommended for the iron produced from ore by the blast furnace. When necessary it can be specified as pig iron when in the form of pigs (usually cold), or as molten iron, commonly called hot metal to distinguish it from cold iron in pigs. The product of a direct process of making wrought or malleable iron from ore is not included.

Jan 1, 1924