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Jan 1, 1943

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members..) Members and guests who registered at institute headquarters during the period Dec. 10, 1915 to Jan. 10, 1916: A. R. Fletcher, Palo Alto, Cal. H. L. Hollis, Chicago, Ill. R. G. Hall,. St. Louis, Mo. Howland Bancroft, Denver, Colo. Walter E. Koch, Terlingua, Tex. G. D. B. Turner, Butte, Mont. George A. Macready, Searchlight, Nev. H. A. Wheeler, St. Louis, Mo. H. W. Edmondson, Concheno, Chili., Mex. George B. Rodgers, St. Francois, Mo. Arthur F. Taggart, New Haven, Conn. Paul S. King, Wilmington, Del. H. V. Winchell, Minneapolis, Minn. G. H. Clevenger, Palo Alto, Cal. Frank A. Ross, Spokane, Wash. J. W. Beard, Syracuse, N. Y. W. D. B. Motter, Jr., Benson Mines, N. Y. Albert De Deken, Louvain, Belgium. S. Le Fevre, Forest Glen, N. Y.. James H. Smith, Jr., Mount Carmel, Pa. E. H. Hamilton, formerly manager of the Virginia Smelting Co., West Norfolk, Va., has become consulting metallurgist to the Consolidated Mining and Smelting Co., of Canada, Ltd., Trail, British Columbia.

Jan 2, 1916

THE Institute assembled in the Hall of the Boston Natural History Society on Tuesday evening. Dr. T. Sterry Hunt, of the Boston Institute of Technology, after a brief address of welcome to the Institute, read an introductory paper on the Geognostical History of the Metals. President Raymond responded to the welcome of Dr. Hunt. The following names were then presented to the Institute, with the recommendation of the Council, for election: Adams, J. M., . . . . . . Silver City, Idaho. Daggett, Ellsworth,. . . . . Salt Lake City, Utah. Geist, Alfred W., . . . . . Boston, Mass. Hays, Dr. S. Dana, . . . . . Boston, Mass. Heinrich, Oswald J., . . . . Midlothian, Va. Johnson, J., . . . . . . Braidwood, Ill. Leckie, Robert G., . . . . . Actonvale, Canada. Lyman, Edward, . . . . ' . Troy, N. Y. Maltby, William, . . . . . Braidwood, Ill. Nichols, Lyman, Jr., . . . . Bbton, Mass. Ordway, Prof. J. M., . . . . Boston, Muss. Rand, Theodore D , . . . . . Philadelphia, Pa. Richards, Prof. Robert H., . . . Boston, Mass. Roclrwell, Prof. Alfred P., . . . Boston, Mass. Roepper, Charles W ., . . . . Bethlehem, Pa. Schulz, A. von, . . . . . Central City, Colorado. Singer, William F., . . . . Pittsburgh, Pa. Spillsbury, E. G., . . . . . New York. Wells, Calvin, . . . . . . Pittsburgh, Pa. The session concluded with the reading and discussion of a paper, by Henry Engelmann, On the Mines and Ores of the Little Cottonwood Canyon, Utah. The second session was held on Wednesday morning, when the following papers were presented : On the Midlothian Coal Mines, by Oswald J. Heinrich. On the Probable Existence of Microscopic Diamonds in California, by Prof. Benjamin Silliman.

By ARTHUR S. DWIGH

Discussion of the paper of W. W. NORTON, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 92, August., 1914, pp. 1993 to 1999. ARTHUR S. DWIGHT, New York, N. Y.-Mr. Norton's chief argument is directed against the idea that the D. & L. sinter is any better material for the blast furnace than the H. & H. product. He supports this by citing two experimental furnace runs. Reducibility.-To discuss a furnace record like that quoted by Mr. Norton for the five days' run in August, 1912, is manifestly difficult for an outsider, but a possible explanation for the poor reduction on Furnace No. 5, smelting D. & L. sinter, may lie in the fact that both sets of furnaces carried the same fuel charges. Other things being equal, if 11 ½ per cent. coke was right for the furnaces smelting H. & H. product, it Was too much for the furnace smelting D. & L. product, as I shall endeavor to show later, and incipient overfire, accompanied by higher leads in slag and matte, was induced. It may sound like a paradox to say that excessive fuel sometimes produces poor reduction, but it is a sad fact. In certain plants where practically the entire charge to the blast furnaces receives a preliminary treatment by being sintered on the D. & L. machines the peculiarities of this problem have had to be very carefully studied, for serious metallurgical difficulties presented themselves when the change was first made to D. & L. sinter in large quantities. Some of these plants had blast pots before they had D. & L. machines, and many opportunities were afforded for comparative study of this very point. There is reason to believe that, clue to the long period of blowing and the higher temperatures developed in the pots from greater mass action, the iron in the H. & H. product is present chiefly as Fe203, perhaps in the form of ferrites, while in the D. & L. product the iron is present as FeO. The fuel charge in the blast furnace must be so proportioned as to exactly meet the chemical and thermic requirements of reduction and melting. If ally of these functions have been performed before the material enters the furnace, a corresponding allowance should be made or the fuel balance will be disturbed and bad work will result. One of the functions of the coke is to reduce enough metallic Fe for the matte requirements, leaving the remainder of the iron as FeO to go into the slag. In smelting almost any other material than D. & L. sinter the iron must-be reduced from the higher oxides, Fe203 or Fe304, to the protoxide, FeO, before a true comparative basis is reached. Experience has shown that with about one-half D. & L. sinter on the charge the coke should-be cut about 10 per cent. This theoretical benefit is borne out by the practical blast-furnace results on a large scale in numerous plants. In fact, wherever this very important factor is ignored the evil symptoms of excessive fuel will be indicated,

Jan 11, 1914

By R. M. Lumley, J. D. Wood

In this investigation, polyethylene terephthalate (Mylar) was coated with various thicknesses of a vapor-deposited silvel- precoat followed by a uapor-deposited zinc using several orders of- magnitude variation in deposition rate of both the silver and zinc. The grain size and resistivity of the zinc film was primarily a function of the silver precoat thickness (in the range of 0.001 to 10 average Agprecoat thickness) and a secondary function of the zinc film thick-ness. The silver and zinc deposition rates were found to have a minor effect on the characteristics of- the zinc film. Electron and X-ray dilffraction results slwwed that all zinc films exhibited a fiber texture mith the (0001) axes essentially perpendiculav to the platze of the film When coating nonmetallic substrates such as paper or plastics with zinc metal vapors, it is found that the zinc will not condense unless extremely high evaporation rates or very low substrate temperatures are used. In 1931, Fraser' reported a procedure whereby zinc could be made to condense on nonmetallic substrates by depositing a very thin precoat of silver. Utilizing Fraser's method, the ermans' developed a commercial process of making "metallized film" capacitors during World War 11. The metallizing process, which was introduced in the United States shortly after the conclusion of World War 11, became one of the first large-scale commercial applications of vapor-deposited metal films and remains one of the larger applications in the electronics industry. The process, as developed by the Germans, consisted of depositing a thin precoat of silver on lacquered, kraft paper followed by a conducting layer of zinc. The resulting silver-zinc film was used as the capacitor The term silver-zinc will be used throughout thiz paper to mean a metal film formed by an extremely thi layer of silver, 10A or less in average thickness, and a zinc film IOOA or more in thickness deposited on the silver film. ---. electrode with the lacquered paper being the dielectric. When polyethylene terephthalate was marketed by E. I. Du Pont Co. in the early 1950's under the trade name Mylar it was substituted for the kraft paper in many capacitor applications. Even though manufacture of metallized paper and metallized Mylar capacitors has been a large commercial process for many years, little information has been published about the deposition parameters. Correlating the work of others to the various effects to be expected of deposition parameters on silver-zinc films deposited on Mylar, it is expected that the

Jan 1, 1967

By John F. Elliott, Martin Weinstein

The solubility of hydrogen in liquid Pure iron and in a number of liquid binary iron alloys has been measured in a Sieverts'-type apparatus. Sieverts' law is obeyed in all alloys studied UP to 1 atm Pressure H2. The alloying elements, Al, B, C, Co, Cu, Ge, P, S, and Sn, decrease the solubility while Cb, Cr, Mn, and Ni increase it. ALTHOUGH the importance of hydrogen in steel-making has long been recognized, there has been, until recently, very little information in the literature on the effect of alloying elements on the solubility of hydrogen in iron. There is also disagreement on the solubility of the gas in liquid pure iron. Because of the earlier work in this laboratory,1,2 with the Sieverts method to determine the solubility of nitrogen in liquid iron alloys, it was decided to apply the equipment and procedure to hydrogen. The literature that is pertinent to this study (Ftefs. 1 through 15) will be discussed later when the results of this investigation are considered rather than at this point to avoid repetition. The reaction under study is:

Jan 1, 1963

By William Sharp

Discovery of new ore in the Eureka district, Nevada, as a result of bold and persistent exploration based on a geologic interpretation of structure has recently aroused wide comment in mining circles. It may therefore be of interest to the profession to have a summary of the historical background and an account of the recent program of development. The mines of Eureka, discovered in the late 1860's, were the first important silver-lead mines in the United States. They have a production record of more than fifty-one million dollars.' After the ore bodies were apparently bottomed in the 1880's, repeated attempts to find new ore were unsuccessful until 1940, when a diamond-drill hole cut a 40-ft width of sulphide ore 1409 ft below the 841-ft level of the Locan shaft. The next hole cut 30 ft, of ore and three additional holes drilled in 1943 and 1944 showed the ore body to be continuous, Shaft sinking to reach and open up the ore body has been in progress since 1945. Geology Stratigraphy The ore in the Eureka district occurs in a series of Cambrian sediments which is exposed through a thickness of over 6000 ft. The stratigraphic column is as follows:2 Thickness. Ft Ordovician : Pogonip limestone (upper part). Thin bedded limestone with some chert. Upper Cambrian: Pogonip limestone (lower part). Thin-bedded limestone (with shaly limestone and chert).... 425 + Dunderberg shale. Shale (clay and calcareous shale) and thin-bedded limestone............. 34°+ Hamburg dolomite. Dolomite and limestone.................... 900+ Middle Cambrian: Secret Canyon shale. Shale and thin-bedded limestone........ 1,035 Geddes limestone. Carbonaceous, flaggy limestone with some shale partings................ 335 Middle (?) and LoweR Cambrian: Eldorado dolomite. Dolomite and limestone.................... 2,000 Lower Cambrian: Prospect Mountain quartzite. Quartzite with occasional intercalated conglomerate and shale 1,660+ The Prospect Mountain quartzite has been subdivided into two formations: Upper part, Pioche shale. Shale, quartzite with some intercalated limestone (Lower Cambrian fossils)-200 ft. Lower part, Prospect Mountain quartzite proper- 1,460Sft. Total thickness................ 6,695 + Much the most productive of these formations has been the Eldorado dolomite, which yielded more than $42,000,000 at Ruby Hill and an additional amount

Jan 1, 1949

By William Sharp

Discovery of new ore in the Eureka district, Nevada, as a result of bold and persistent exploration based on a geologic interpretation of structure has recently aroused wide comment in mining circles. It may therefore be of interest to the profession to have a summary of the historical background and an account of the recent program of development. The mines of Eureka, discovered in the late 1860's, were the first important silver-lead mines in the United States. They have a production record of more than fifty-one million dollars.' After the ore bodies were apparently bottomed in the 1880's, repeated attempts to find new ore were unsuccessful until 1940, when a diamond-drill hole cut a 40-ft width of sulphide ore 1409 ft below the 841-ft level of the Locan shaft. The next hole cut 30 ft, of ore and three additional holes drilled in 1943 and 1944 showed the ore body to be continuous, Shaft sinking to reach and open up the ore body has been in progress since 1945. Geology Stratigraphy The ore in the Eureka district occurs in a series of Cambrian sediments which is exposed through a thickness of over 6000 ft. The stratigraphic column is as follows:2 Thickness. Ft Ordovician : Pogonip limestone (upper part). Thin bedded limestone with some chert. Upper Cambrian: Pogonip limestone (lower part). Thin-bedded limestone (with shaly limestone and chert).... 425 + Dunderberg shale. Shale (clay and calcareous shale) and thin-bedded limestone............. 34°+ Hamburg dolomite. Dolomite and limestone.................... 900+ Middle Cambrian: Secret Canyon shale. Shale and thin-bedded limestone........ 1,035 Geddes limestone. Carbonaceous, flaggy limestone with some shale partings................ 335 Middle (?) and LoweR Cambrian: Eldorado dolomite. Dolomite and limestone.................... 2,000 Lower Cambrian: Prospect Mountain quartzite. Quartzite with occasional intercalated conglomerate and shale 1,660+ The Prospect Mountain quartzite has been subdivided into two formations: Upper part, Pioche shale. Shale, quartzite with some intercalated limestone (Lower Cambrian fossils)-200 ft. Lower part, Prospect Mountain quartzite proper- 1,460Sft. Total thickness................ 6,695 + Much the most productive of these formations has been the Eldorado dolomite, which yielded more than $42,000,000 at Ruby Hill and an additional amount

Jan 1, 1949

Truman H. Aldrich W. Lawrence Austin W. S. Ayres John Henry Banks Wrn de L Benedict Andrew A Blair Walter M. Brodie H. H. Burden Charles Butters

Jan 1, 1932

Truman H. Aldrich John H. Allen W. Lawrence Austin W. S. Ayres John Henry Banks Wm de L. Benedict Robert Bentley Andrew A Blair Walter M. Brodie

Jan 1, 1934

Truman H. Aldrich John H. Allen W. Lawrence Austin W. S. Ayres John Henry Banks Wm de L. Benedict Robert Bentley Andrew A Blair Walter M. Brodie

Jan 1, 1934

AT a luncheon attended by engineering leaders representing every section of the country, Col. Arthur S. Dwight, president of the American Institute of Mining and Metallurgical Engineers, and Charles F. Rand, chairman of the Engineering Foundation, past president of the Insti-tute and its present treasurer, on Thursday, July 20, were decorated with the Croix de Chevalier de la Legion d'Honneur by the French Government for distinguished service in engineering tending to closer and more felici-tous relations between the two countries. The decorations were conferred by Consul General Gaston Liebert. In a speech extolling the war work of the American engineer, M. Liebert declared that Germany had been definitely foiled in her attempt to cripple France industrially for a generation by wrecking the coal mines of northern France. Three-fourths of these mines, M. Liebert said, were in full working order and the remainder will be in complete operation within two years. The Germans thought that it would take from 15 to 20 years to accomplish this. M. Liebert said that reconstruction is going on rapidly in northern France, two-thirds of whose indus-tries are now working. The French Government, he said, is planning water-power improvement on a vast scale, which will soon make unnecessary for France to import a single ton of coal. He urged that French students be sent to America to study engineering. In presenting the decorations, Consul General Liebert eulogized Colonel Dwight and Mr. Rand as personify-ing the spirit and service of the American engineer, which, he said, was a powerful factor in the victory over Germany. He spoke of the growing friendliness between the United States and France and described this ceremony as an epoch in international relations. Calvin W. Rice, secretary of the American Society of Mechanical Engineers, who presided, repeated that international unity among engineers was the dream of Andrew Carnegie, who saw in the efforts of the engineer and the scientist the hope of civilization. Mr. Rice said in part: In the Declaration of Independence occurs the statement that all men are created free and equal. Jefferson was familiar with the writings of Rousseau. In fact, he was a remarkable linguist notwithstanding that he wrote the Declaration of Independence when only 32 years of age. He was one of the very few ambassa-dors in the history of the United States who could speak the language of the country to which they were sent. The interpretation of the passage in the Declaration of Independence is that all men have equal opportunity, not that they are born with equal ability.

Jan 8, 1922

By C. Perez-Rosales

A statistical method for determining simultaneously some of the basic geometrical characteristics of porous media such as porsity, specific surface* mean pore width, mean grain thickness and absolute permeability is presented. The proposed method is characterized by its simplicity and the minimum amount of laboratory equipment that it requires. The experimental procedure used to evaluate the various geometrical characteristics is based 'pan the 'surface analysis Of a a In view of this fact the app1icability Of the method is limited to homogeneous and isotropic materials. INTRODUCTION The behavior of a fluid flowing through a porous medium depends, among other things, upon the internal geometry of the medium; hence the importance of developing efficient methods to determine the geometrical properties of porous materials. This paper describes a statistical method to determine simultaneously some of the basic geometrical properties of porous materials such as porosity, specific surface, mean pore width, mean grain thickness and absolute permeability. The mathematical formulation has been developed that the data required to calculate the various geometrical characteristics of a sample can be easily measured by analyzing a section of the sample with an evenly spaced grid. THEORY A simple way of obtaining information about the internal geometry of a porous material is to throw a point at random over a cross-section of a sample. l-Through this procedure the porosity can be detemined.l,2 By considering that the material is homogeneous and isotropic, and that the point is dropped many times, the porosity 4 is given by where N is the total number of times the point is thrown and n is he number of times the point falls within pore areas. Another simple manner of analyzing the structural characteristics of a porous material is to superimpose an arbitrarily long line on a cross-section so that its length is evenly distributed over the surface area. Through this procedure the porosity can also be determined. If L is the total length of the line, and 1 is the sum of the lengths of the line segments within void spaces, the porosity is given by 4 = —.1.............. (2) The advantage of this type of analysis is that geometrical characteristics other than porosity can be obtained. Thus, if c represents the number of intersections between the line and the perimeter of pores, it can be shown3 that the specific surface, defined as he surface area of pores per unit bulk volume, is given by To give a proper description of the internal geometry of a porous medium, it is necessary to define quantities that characterize the notions of pore size and grain size. Unfortunately, because of the complexity of porous materials, it is difficult to give exact geometrical definitions of what is meant by the ConCePtS of "poresl' and "grains", especially when dealing with consolidated materials. Never theless, one often talks about the "size of pores" and the "size of grains" without defining accurately the terms. A possible solution to this problem follows. Assume that an arbitrarily long line is placed on a section of a sample so that the line is evenly distributed over the surface area (see Fig. 1). 1n a system like this, each line segment within a void space will be, by definition, the pore width in a given location and direction. Consequently, if the

Jan 1, 1970

By Wells A. Hutchins

Water laws important to the mining industry are those which govern or affect the right to use water, to dispose of water after using it in mining or milling, and to discharge waste material into water-courses. They include statutes and court decisions having general applicability, as well as others that pertain specifically to mining. THE INDUSTRY'S CONTRIBUTION TO WESTERN WATER LAW Despite sharp differences of opinion, the water law the Spaniards brought to the Southwest appears to have included some form of appropriation of water. The Mormons, who settled in Utah in the mid-nineteenth century, also developed a system of appropriative water titles. But by far the most profound impact on western water law was made by the gold- seekers who flocked to the Sierra Nevada foothills of California after the discovery of gold in 1848. Much of the gold was extracted from the ground by hydraulic or placer mining, and so the-miners' rights to the use of water became fundamentally important. Since there was no organized government in the foothills and no laws other than those made by the miners, they helped themselves to the land, the gold, and the water needed to work their claims.' They established and enforced regulations governing the acquirement and holding of mining claims and their rights to the water they needed.'In 1879 Justice Field, former Chief Justice of the California Supreme Court, spoke for the U. S. Supreme Court in saying that the miners were "emphatically the law-makers, as respects mining, upon the public lands in the State.""

Jan 2, 1960

By Julian Nardi

Pumping solids through a pipeline is not new but until very recently other means of transportation were cheaper. Many proposed pipelines for transporting solids, while technically feasible, have not been attractive enough to warrant the financial risk involved. In some instances, the difference in transportation cost was negligible. In others, the threat of pipeline competition resulted in a slashing of rates on existing transportation to the point where a pipeline could no longer be justified. In others, a competitive product was cheaper. FIRST IN PLACERS The earliest record of solids being transported in a pipe was in the late 1850s in California placer mines. Water under pressure was used to force gold-bearing gravel up through a pipe, from 30 to as much as 55 ft, to a point where it could be discharged into a flume or sluice.

Jan 9, 1959

By William D. Manly, John Towers, Paul A. Beck

RECENT work on grain growth in high purity aluminum and in a solid solution type alloy of aluminum and magnesium' showed that the isothermal increase of the average grain diameter D with time follows the equation [D = K(to + A)-Eq I] Here [to] is that portion of the total annealing time [t], which is available for grain growth, i.e. the annealing time less the time necessary for complete recrystallization. The parameters A and n depend only on the temperature. A has the dimension of time, and is usually of the same order of magnitude as the time for recrystallization: R. In some instances R may be substituted for A in Eq I. This is the case for example at long periods of annealing or at high temperatures, where both A and R become small in comparison with t. In such instances Eq I is simplified to [D-K-tnEq2] For high purity aluminum the exponent n increases in the ratio of about 1 to 5 in the temperature range of 350° to 600°C. 70-30 brass has been long known to exhibit grain growth of the continuous type, such as occurs in pure metals. For this reason, it was of interest to determine whether grain growth in brass also follows Eq I and 2 as it does in aluminum. Isothermal grain growth data for 70-30 brass were published in recent years by R. S. French2 and by H. L. Walker3 Fig I shows a log D vs. log t plot of French's data, together with the 500, 600 and 100°C data by Walker for 42.8 pct reduction by rolling. In such a log D vs. log t plot Eq 2 corresponds to a straight line with a slope of n. As seen in Fig I, the data of French and the 600°C data of Walker can be represented by straight lines. However, the 500 and 700°C data of Walker give curved lines and the average slope of his 500°C line is very different from the slope of the line representing French's data for the same temperature. Furthermore the curvature of the 700°C line suggests a tendency for grain growth to stop after 8 hr. If confirmed, this would constitute a definite deviation from Eq 2, not explainable on the basis of the specimen thickness effect found in high purity aluminum.1 Walker's specimens were 0.125 in., i.e. 3.18 mm thick, while the deviation occurs at a grain size of approximately 0.4 mm. A further point of divergence arose recently, when J. E. Burke suggested4 on the basis of Walker's data, that, instead of Eq 2, grain growth in 70-30 brass follows the equation [D-D. =K• t,Eq3] Here D, is the grain size as recrystallized at the temperature in question. Although it was possible to show5 that, for pure aluminum, for which isothermal grain growth has been carefully investigated, Eq 3 is incompatible with the experimental facts, the situation remained somewhat obscure with respect to 70-30 brass. In view of the discrepancies between the

Jan 1, 1948

By William F. Brace, Howard R. Pratt, Wayne S. Brown

In many engineering structures, the mechanical properties of large volumes of rock must be considered. Typically, such properties are assumed to be the same as those of small laboratory samples, although it is clear that the laboratory samples do not contain the joints, faults, and other natural planes of weakness of the rock mass. A cheap, convenient testing procedure is needed with which the engineer can more accurately assess the strength and elastic properties of natural jointed rock. As a first step in this direction, a test has been developed capable of determining mechanical properties of large samples in their natural undisturbed state. In the present paper, some preliminary experiments on relatively unjointed material are described. Numerous attempts have been made to measure the deformation modulus of rock masses with varying degrees of success. Rocha (1), Grimm (2), and Alexander (3) have placed flat jacks in a slot in the rock and measured the pressure required to deform the slot. Bonnechere (4) has grouted large flat jacks in granite masses and performed similar experiments using a variety of strain measuring techniques. The U. S. Bureau of Mines has conducted radial jacking tests in which a uniform radial stress is applied to the inside of a tunnel of circular cross section and radial deformation is measured by extensometers located at various depths in the tunnel fall. Plate jack tests (Rocha (5), Shannon and Wilson (6)), pressure chamber tests, and cable jacking tests (Zienkiewicz and Stagg (7)) have all been used to determine in-situ deformation modulus. Several bore hole techniques have also been used to measure rock deformation. These include bore hole jacks (Goodman (8)), bore hole dilatometers using expandable membranes (Menard (9)) and bore hole penetrometers. Most of the above tests except the radial jacking test have an unknown stress distribution and require considerable approximation to calculate a deformation modulus. These approximations include the use of elastic theory for solutions of rigid plates, thick-walled cylinders, etc., and determination of values for Poissons

Jan 1, 1971

By George M. Schwartz, Ian L. Reid

The Soudan mine in the Vermilion district of northeastern Minnesota is the oldest iron mine in the state. It has shipped ore every year since 1884 and still contributes a yearly quota of high grade lump ore. No comprehensive report on the Vermilion iron-bearing district has appeared since Clements' monograph,' but Gruner' discussed the possible origin of the ores in 1926, 1930, and 1932, and recently Reid and Hustad have added data on mining and geology." For many years geologists of the Oliver Iron Mining Div., U. S. Steel Corp., have kept up to date a series of plans and vertical sections of the Soudan mine. In connection with mine operation considerable diamond drilling has been done, and this, together with the mine openings, has permitted a reasonably accurate picture of the structure of the orebodies and wall rocks.

Jan 3, 1955

By D. W. Frommer, M. M. Fine

Mineral dressing research showed that iron concentrates of commercial quality could be produced from the Pea Ridge deposit near Sullivan, Mo. Magnetic separation and flotation, on a laboratory scale, yielded concentrates ranging from 60.0 to 71.4 pet Fe at recoveries of 89.9 to 97.6 pct. Early in 1957 St. Joseph Lead Co. announced discovery of three new centers of iron ore deposition in east central Missouri.' The discovery resulted from exploratory drilling in the vicinity of a magnetic anomaly or high. A deep hole, drilled into the Pre-Cambrian porphyry to determine the cause of anomaly, penetrated a magnetite-rich deposit.' The magnetic surveys that revealed the anomalies were begun by the Missouri Geological Survey in 1929 and were continued into the 1930's.3 At that time an area in Crawford County known as the Bourbon magnetic high was located. A second anomaly, similar in size and intensity, was discovered about six miles to the northeast in Franklin County in the vicinity of Sullivan. This area was not studied in detail until the early 1940's. To determine the cause of the anomalies, the USBM drilled four holes at the Bourbon site in 1943-1944.4 The most productive hole penetrated four mineralized zones having a total thickness of 127.5 ft. These zones contained magnetite in rhyo-lite porphyry at depths between 1600 and 2000 ft. Additional iron ore below 2000 ft was considered a possibility at the time. Some years later, the USGS, Missouri Geological Survey, St. Joseph Lead Co., and others cooperated in sponsoring an aeromagnetic survey of the Bourbon-Sullivan area which resulted in discovery of a third high, about eight miles distant at Pea Ridge. This deposit, with an estimated reserve of 50 to 100 million tons of iron ore, is considered the main find, although other orebodies in the same general area are of definite interest.' When this discovery was announced, St. Joseph Lead also revealed plans to exploit the deposit jointly with Bethlehem Steel Co. A new corporation, Meramec Mining Co., was established, and 1962 was set as the target date for completing physical plant.2 Annual production goals of 2 million tons of beneficiated and pelletized iron ore were proposed. Preparation of the site for shaft sinking was begun in June 1957. Orebody and Character of Samples: Drilling to date has established the Pea Ridge orebody as a crescent-shaped pipe about 300 ft wide. Some drillholes were bottomed at 2800 ft in very good iron ore.6 he orebody is predominantly magnetite, although hematite and a mixture of hematite and magnetite occur in the upper areas and peripheral walls. Drillhole cores representing ore from different areas and depths of mineralization were grouped into composites for testing. These composites consisted of: 1) medium grade mixed hematite and magnetite, 2) high grade mixed hematite and magnetite, and 3) high grade magnetite. The medium grade ore came from three holes with depths of i350 to 1900 ft. The high grade mixed hematite and magnetite cores came from the 1790 to 2812-ft interval of one hole. Partial chemical analyses of the three samples, given in Table 1, reveal that all are excessively high in phosphorus and sulfur, and sample 1 is

Jan 1, 1960

By L. G. Austin, P. T. Luckie, R. R. Klimpel

Application of the Charles and Bond Laws to batch grinding can be deduced as a special case of solution of the first-order batch grinding equation. With additional limitations on the feed size distribution, this special case also gives Rosin-Rammler distributions of constant slope, with the 36.79% retained point a simple function of time. In general, the assumptions concerning the breakage parameters S and B which are necessary to get Charles' and Bond's laws, are not valid except as a crude approximation. With less restrictive assumptions, it is still possible to get approximate Rosin-Rammler distributions, but the slopes change with time of grinding, and the 36.79% retained point is a more complicated function of time. An alternative form to Charles' law is suggested, which accomplishes the same result and has the same errors, but avoids the use of energy of grinding and deals with specific rate of grinding.

Jan 1, 1973