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By J. L. Gillson

In a brief summary of the many occurrences of fluorspar in our western states, it is not possible to go into detail in regard to the geology, mining and milling methods, and reserves about individual deposits. Rather a broad review is made of the occurrences and an analysis of how the western deposits may fit into our future domestic economy is presented. General Statement on Fluorspar Situation Fluorspar has been used for years as a flux in the manufacture of basic open-hearth steel, in foundry cupolas for melting pig iron, in the manufacture of opalescent glass and in the preparation of hydrofluoric acid. In 1880 the annual production of fluorspar in the United States was around 4000 tons per year. By 1900 it was up to 21,656 tons and between 1902 and 1908 it averaged about 40,000 tons annually. Prices were then so low, by present standards, that it seems impossible to believe now that mining could have been performed profitably at the price levels then prevailing. In 1890 fluorspar sold at the mines for $6.70 per ton, in 1901 for $5.81, in 1916 for 85.92. When the United States entered World War I, flyorspar production and price skyrocketed; the production reached 263,817 tons in 1918, with prices above $20.00 per ton, and prices were even higher in 1919 and 1920. After 1920, the domestic production fell from the 1918 level to about 125,000 tons annually and the average price dropped back to about $18.00 per ton. By 1935 the average price had fallen to $15.00, but in 1940 with a rising demand the average price of all grades had gone back up to $20.31. Today it is 75 per cent higher than in 1940 and presumably the price of acid grade at .least would be even higher if it were not for price ceilings. The first subsequent year that the domestic production exceeded that of 1918 was 1941, and the 1944 production is expected to exceed 400,000 tons, or over one and a half times that of 1918. In five-year periods, average production and imports were as are shown in Table I. Many people concerned with the consumption of fluorspar believe that the postwar period ahead will show a repetition of price trends of the last such period. They believe that imports will be again an important factor in the available supply and the price will fall back gradually toward the prewar level. The following basic factors are pertinent in analyzing this conclusion:

Jan 1, 1948

By J. L. Gillson

In a brief summary of the many occurrences of fluorspar in our western states, it is not possible to go into detail in regard to the geology, mining and milling methods, and reserves about individual deposits. Rather a broad review is made of the occurrences and an analysis of how the western deposits may fit into our future domestic economy is presented. General Statement on Fluorspar Situation Fluorspar has been used for years as a flux in the manufacture of basic open-hearth steel, in foundry cupolas for melting pig iron, in the manufacture of opalescent glass and in the preparation of hydrofluoric acid. In 1880 the annual production of fluorspar in the United States was around 4000 tons per year. By 1900 it was up to 21,656 tons and between 1902 and 1908 it averaged about 40,000 tons annually. Prices were then so low, by present standards, that it seems impossible to believe now that mining could have been performed profitably at the price levels then prevailing. In 1890 fluorspar sold at the mines for $6.70 per ton, in 1901 for $5.81, in 1916 for 85.92. When the United States entered World War I, flyorspar production and price skyrocketed; the production reached 263,817 tons in 1918, with prices above $20.00 per ton, and prices were even higher in 1919 and 1920. After 1920, the domestic production fell from the 1918 level to about 125,000 tons annually and the average price dropped back to about $18.00 per ton. By 1935 the average price had fallen to $15.00, but in 1940 with a rising demand the average price of all grades had gone back up to $20.31. Today it is 75 per cent higher than in 1940 and presumably the price of acid grade at .least would be even higher if it were not for price ceilings. The first subsequent year that the domestic production exceeded that of 1918 was 1941, and the 1944 production is expected to exceed 400,000 tons, or over one and a half times that of 1918. In five-year periods, average production and imports were as are shown in Table I. Many people concerned with the consumption of fluorspar believe that the postwar period ahead will show a repetition of price trends of the last such period. They believe that imports will be again an important factor in the available supply and the price will fall back gradually toward the prewar level. The following basic factors are pertinent in analyzing this conclusion:

Jan 1, 1948

By James W. Guider

Of all the technology available to the iron blast furnace operator, raw materials preparation [(Fig. 1)] is by far the most important. Superior raw materials have been basic to the success of the Japanese steel industry, and they are just as essential to the American steel industry in winning its competitive battle against foreign government subsidized steel imports. Therefore, the mine operator and the ore beneficiation engineer must strive to produce the highest quality raw materials possible to meet the precise demands of the modem blast furnace and steel plant.

Jan 1, 1982

The primary purpose of the Institute is to advance the technologic and engineering arts embraced by it through interchange of knowledge. This can best be clone by the presentation and discussion of technical papers by its members. Short practical papers are especially welcome. An author should always satisfy himself that his material is of a quality that will he a credit to him and to the Institute. The preparation of a good paper frequently leads to a reorientation of the author's thoughts, and publication contributes much to the professional standing of the author. Members are urged to submit papers presenting the results of their work. Attention to the following suggestions will greatly further the prompt and efficient handling of manuscripts. 1. SUBJECTS: The subject must be within the field of the Institute. Original work, the results of field, plant, laboratory or theoretical investigations, new views on old but important problems and occasionally reviews of timely and important subjects of wide interest to our members may constitute the basis of a paper. The mere fact that the work is original does not necessarily justify publication: it must be of a substantial nature, of value to a reasonable number of our members and worthy of permanent record. It is seldom desirable to subdivide the results of a single research for publication in a variety of journals. Previous publication is usually a bar to acceptance. If any part of your paper has been published elsewhere and you regard repetition as absolutely necessary please so state in your covering letter. 2. CONSTRUCTION: Papers should be clearly and concisely written in good English. Care in this regard ensures wider reading and the saving in space permits the Institute to publish more papers. It is the experience of the Papers and Publications Committee that most papers can he improved by condensation. "Readers" who are asked to recommend acceptance or nonacceptance put particular emphasis on the length of the paper and the elimination of unnecessary or any extraneous material. The terminology and units employed should be those current in the particular field. An examination of Institute publications will afford useful guidance in such matters. Webster's New International Dictionary, 1935 edition, is the Institute's authority for spelling and style. Various abbreviations are used habitually; for instance, lb., pound; bbl., barrel or barrels; ft., foot or feet; hr., hour or hours; in., inch or inches; Fig. 1 but Figs. 2 and 3.

Jan 1, 1946

By David R. Mitchell, Ernest M. Spokes

MINING ENGINEERING, page 373, March 1958, vol. 211) S. C. Sun: This article by Spokes and Mitchell deserves high commendation. For many years mineral dressers have been at a loss to explain the variation in magnetic susceptibility of the same mineral species obtained from different localities. In fact, they do not even have a list of accurately measured data on the specific magnetic susceptibility of weakly magnetic minerals to consult. Experience as a university teacher has firmly convinced me that the average student has more difficulty in acquiring a satisfactory knowledge of magnetism than of any other branch of mineral dressing. This is almost entirely because the subject has been treated far too much from a strict practical standpoint and far too little from a fundamental one. It is no exaggeration to state that almost all the published theoretical discussions are based on the experimental results of manufactured chemicals and alloys, but not of naturally occurring minerals. In an attempt to remedy this state of affairs, the author of this article not only set up a new magnetic balance in the Department of Mineral Preparation of The Pennsylvania State University, but also performed work of fundamental value, thus pointing the way to further research. This is evidenced by the fact that an investigation of the magnetic susceptibilities of manganese minerals was recently completed by S. G. Watt under the direction of David R. Mitchell, now acting dean of the College of Mineral Industries of the Pennsylvania State University. D. J. Cook is studying the magnetic susceptibility of titanium minerals under my supervision. It is hoped that our research program can be continued for several years and that similar investigations will be initiated at other universities and research institutions. Ernest M. Spokes (author's reply): The discusser has touched the heart of a pedagogical problem in the field of minerals beneficiation—students do not understand magnetism and, as a result, neither do the graduate engineers. Only recently has the average course in engineering physics started teaching the fundamentals of magnetism, as they are understood in modern physics, in addition to the classical treatment of the mathematical aspects of magnetic phenomena. It is to be hoped that this increasing instruction in fundamentals will improve our understanding and inspire research to determine more of the basic magnetic data that are essential if we are to see improved methods of separation by magnetism.

Jan 1, 1959

By Franklin G. Pardee

WARTIME depletion of the reserves of iron ore in the Lake Superior region of the grade and character now being shipped down the Lakes was serious. The time has come to take stock of the resources that remain in order to plan our future program of supply for our blast furnaces and protect, as far as possible. the tremendous investment made in the Lake Superior iron mining industry. Hugh M. Roberts and William H. Crago have estimated the reserves of the Lake Superior region in the United States at two billion long tons. These reserve figures are of direct-shipping ore and those concentrates produced by methods now in commercial use or those methods that may be expected in the near future. In their estimate they have assigned 392 million long tons to the Michigan ranges (all reserves in long tons) : 112 million tons for the Gogebic. 140 million tons for the Menominee, and 140 million tons for the Marquette.

Jan 1, 1948

By Clyde E. Williams

IN planning a postwar program for manufactured products, it is essential that the bases for the plans be wisely chosen. First we must make certain assumptions as to the war's ending. Let us assume: (1) complete victory by the United Nations, (2) peace terms that will ensure the direction of the economy of all nations of the world toward peaceful pursuits, and (3) an early ending of the war, that is, before the nations of the world, excluding the enemy, are near the point of physical and spiritual exhaustion. Thus, our manufacturing plants and transportation facilities will still be in good shape. The plants and transportation facilities, as well as the cities of a large part of Europe, however, will be badly crippled. The rich mineral and other raw material resources of the world, little of which was under control. of the Axis powers before the war or will be after the war, will not be used up. Control of these raw materials, or at least an important part of them, will remain in the hands of the strong peaceful nations.

Jan 1, 1943

By H. A. Wahl, J. M. Campbell

This study extends our information on solid-liquid slurries to the flow of sand in horizontal fractures. Inasmuch as this is basically an unsteady-state process, a comprehensive photographic study was undertaken in a 10-ft windowed cell to determine if the basic flow regimes described for steady-state flow in pipes applied to the subject process. Since the number of potential variables far exceeds the capacity of a single study, emphasis has been placed on the effects of sand concentration, oil viscosity and oil flow rate. The extensive photographic evidence obtained has proven very valuable in gaining an insight into the basic flow mechanisms. Being able to follow visually the flow characteristics that accompany the quantitative data is valuable in the application of the results. Although the use of dimensionless parameters was carefully investigated. it was found that the data obtained could be more easily, and as accurately, correlated by judicious use of the dimensional variables investigated. However, a study into the feasibility of scaling slurry flow was made in the event this technique is justified in future investigations. The data presented show that the pressure behavior observed in solids transport in pipes basically applies to slurry flow in horizontal fractures. The roles of the parameters are altered but a basic equivalence exists. The most significant correlating parameter was the oil viscosity (µo) and the bulk velocity of the slurry (vn), expressed as ''µv" product. The most significant correlation expresses the rate of advance of the sand as a function of the variables investigated. There are many practical ramifications of this phase of the investigation that should aid in better treatment design. Evaluation of sand advance rates provides a means of estimating sand placement efficiencies during a treatment and the resulting sand distribution in the fracture. The results show that sand placement efficiencies are low under typical treatment conditions. A brief description of the effects of overflushing is also included. INTRODUCTION The flow of sand-oil slurries in fractures is an area in which little basic knowledge is available. This stems to some degree from the fact that it is impossible to duplicate fractures at the surface. They occur in various shapes and sizes with an infinite combination of irregularities. Unfortunately, we can never "see" these fractures except in cores and by indirect means of measurement. In spite of this inherent difficulty, it is desirable to develop some basic concepts that will provide a better understanding of the sand transport mechanism. An insight into the problem is provided by investigations of fluid flow in rectangular conduits. Several studies on the flow of liquids in non-circular conduits1,13 show that a Reynolds number-Fanning friction factor relationship can be written if the hydraulic diameter is substituted for the regular diameter in a circular pipe. This hydraulic, or equivalent, diameter is taken as four times the cross-sectional area occupied by the flowing fluid divided by the wetted perimeter. Eq. 1 expresses an extension of this same work when applied to infinite parallel planes b distance apart.' Eq. 1 is a theoretical equation expressing the friction factor as a function of the Reynolds number for laminar single-phase fluid flow. This expression has been verified experimentally. The equivalent expression for a smooth circular conduit differs only in that the value of the constant is 16 instead of 24. Numerous studies have related friction losses to Reynolds number in both circular and non-circular conduits. These results are widely used and are not reviewed here. Huitt' investigated the effect of surface roughness on fluid flow in simulated fractures. He concluded that fluid flow in fractures may be treated similarly to fluid flow in circular conduits. This work, together with that of Nikuradse,' shows that surface roughness has no appreciative effect upon the resistance to flow in the viscous flow region. In the region of turbulent flow, surface roughness is a prominent factor. Hydraulic conveyance literature is another important source of information. Durand3 has attempted to organize systematically the variables involved in hydraulic-solid transport in pipes. He has classified the modes of flow into three types according to the size of the particles in the mixture— homogeneous mixtures, intermediary mixtures and heterogeneous mixtures. With the usual concentrations and flow rates used in hydraulic transportation, particles with diameters of less than 20 or 30 microns form eszentially homogeneous mixtures with water. The data show, however, that even small materials will tend to settle out under laminar flow conditions. Mixtures containing solids over 50 microns in diameter do not achieve total homogeneity even under turbulent flow conditions. Particles from 50 microns to 0.2 mm in diameter may be transported in fully suspended flow at normal transport velocities although the concentration in the vertical plane is not uniform. Above 2 mm in diameter solid materials are transported along the bottom of the conduit at a velocity substantially less than that of the liquid itself. Between 0.2 and 2 mm in diameter, the particles tend to be in a transition zone between heterogeneous suspended flow and deposit flow at normal hydraulic transport velocities. The sand sizes used in fracturing usually fall in this size range. It is interesting to note that the grain size range designated by Durand for this transition zone corresponds closely to the transition zone between

DURING September, the Coal Commission pre- pared for issue a series of 18 reports on varied aspects of- the bituminous coal industry; the final report, dated Sept. 22, sums up the facts and offers recommendations addressed to Congress, to the industry, and to the public. The few following paragraphs are selected: Bituminous coal is the real foundation of that great industrial and transportation structure which enables more than a hundred million people to live in America and be so well supplied with things necessary for their health, comfort; and convenience; it also furnishes domestic fuel for two-thirds of the homes of the land. The distribution of the output of the bituminous mines tells the story: 28 per cent. goes to the railroads, 25 per cent. to the boiler houses of factories and mills of all kinds, 15 per cent. to the coke ovens and gas plants, 10 per cent, to the homes, 7 per cent. to steel plants and the same percentage to power plants and street railways, 4 per cent. is exported, 2 per cent is used for power at the coal mines, and the remaining 2 per cent. goes to the seaboard for steamship fuel. Bituminous coal enters into interstate commerce on a scale approached by no other commodity; less than a fourth of the coal mined in the United States fails to enter interstate com-merce. All but one of the 45 coal producing districts in the United States ship coal outside the State in which it is mined. Three hundred miles of cars loaded with coal is the daily output of the bituminous mines of the United States. The public-welfare element in coal is seen in the dependence of public health and safety on an unfailing supply of fuel, in the close connection between the prosperity of most industries and the uninterrupted operation of the coal mines, and in the obvious fact that without coal the great network of railroads which binds together this great country would be idle. The railroads and the public utilities, themselves so clearly obligated to render what-ever public service is demanded of them that the constitutionality of their public regulation is unquestioned, are of all industries most dependent upon coal. Thus, coal makes up over 35 per cent. of the operating cost at the gas plant and over 25 per cent. at the electric power station, and in the operating expenses of. a railroad the cost of coal is the largest single item, next to labor. The practical logic that half a century ago clothed with a public interest the steam locomotive and in later years the electric-power station must recognize a large element of public service in the coal mine that furnishes the necessary energy to both locomotive and power-plant.

Jan 10, 1923

By H. P. Willard, Conrad Martin

SINCE the deposits were found in 1927 in the Paradise Range of western Nevada, more than 1 mil- lion tons of magnesite and half a million tons of brucite have been mined and processed into a variety of granular refractory materials used as furnace linings by the steel industry. An additional million tons of magnesite were used during World War II to produce magnesium metal, and some magnesium oxide from the area is going into magnesia cements. Located near Gabbs, Nev., on the west flank of the Paradise Range, the principal bodies occupy an area a mile long by half a mile wide, and lesser occurrences have been found in a belt more than four miles long and in places almost two miles wide. Magnesite reserves containing less than 5 pct lime are estimated at more than 25 million tons. Reserves of better grade material are considerably less.

Jan 4, 1957

By Holt, Grover J.

PRIOR to :1937 any discussion of mining and transportation in the iron mines of Minnesota would have been limited largely to conventional methods which have been used for years in the iron ore industry. Today, however, an inspection trip to the crest of almost any open pit on the ranges will re- veal great progress underground mining and the transportation of underground ore have also developed rapidly and if and when underground mining of iron ore again becomes generally economically feasible; these mining methods will probably witness a transformation equal to that which has taken place in the open pits.

Jan 1, 1941

By John Brownson

Ge-Si N-N heterodiodes hare been built recently which show promise as high-speed logic devices. Low-resistivity germanium is deposited on silicon substrates held at temperatures above the germanium melting point and an alloyed heterojunction formed. The diodes are fabricated from this material using conventional mesa techniques. Over-all device qualify has been greatly improved by the use of epitaxial silicon substrates, that is, a subsirale consisting of a film of thin, high -resistivity silicon on a thicker Piece of low-resistirily silicon crystal. A semimpirical device design equation has been devised which predicts switching performance fairly well within the range of resistivitics and geometries employed. Switching times 01 0.9 ns and PIV 's of —20 v are typical of the better 10-ma diodes. Switching times as low as 0.5 ns have been observed for 10-ma diodes and as low as 2.8 ns for 200-ma diodes. With further development it should be possible to improve switching speed by a factor of four. IN our laboratory, Ge-Si heterodiodes have been built recently which show promise as high-speed logic devices. The diodes have been built using a process reported in some detail in an earlier publication.' The process in short involves alloying a thin film of low-resistivity germanium into a silicon substrate. the germanium having been transported and deposited by the well-known Theuerer halide reduction process.2 This process contrasts with that reported earlier by Oldham who used an essentially conventional direct epitaxial deposition technique.3 Oldham's process, unlike ours, requires cleavage of the silicon sample inside the reactor furnace the instant prior to deposition. Our process has the advantage of yielding large-area macro-scopically plane heterojunctions. Heterodiodes in general have several interesting properties. Without attempting to summarize the theory of heterojunctions.4 two of these properties which have direct relevance should be mentioned. First, N-.V and P-P heterojunction diodes rectify alternating current. Provided that either the band gap or the electron affinity of the two materials is different (which in general is the case), electronic barriers will exist in the junction band structure. When the device is sufficiently forward-biased, the barriers shift so as to permit current flow, and when it is reverse-biased. the barriers block current flow. Second, for N-N and P-P heterodiodes. the foward-conduction process involves majority carriers only. Consequently. when such a device is turned off. there is no minority-carrier storage and hence the diodes switch on and off quite rapidly. As we have reported earlier. N-P and N-N Ge-Si heterodiodes have been built in this laboratory. As one would predict from theory, the N-P heterodiodes were rather slow in turning off while the N-N's were quite fast. Similarly, the turn-off time of the N-P's increased rapidly with forward current while that of the N-N's was independent of forward current. Both N-N's and N-P's were moderately photosensitive. Photocurrents resulting from normal room illumination were as high as 1 µa at 1 v for small-area devices. The most disappointing parameter of the early N-N devices was reverse leakage.' The reverse characteristic was invariably "soft" and leakage at only several volts reverse bias was intolerable. The reverse characteristic was greatly improved by using higher-resistivity silicon substrates. Leakage becomes large at voltages about one third of the avalanche voltage one would expect of a P-N homo-junction formed on silicon of the same resistivity. Thus leakage could be reduced to reasonable limits by using unconventionally high-resistivity silicon. Medium-power diodes formed on 30 ohm-cm substrates leaked typically 15 to 50 µa at 100 v reverse bias. The use of high-resistivity silicon substrate material, however, created a new problem. In order to have an acceptable forward-conductance characteristic. the area of the diodes had to be increased. With this increase in area, the capacitance increased. Switching time for N-N heterodiodes is essentially a linear function of capacitance. Thus when the resistivity was raised. so was the switching time. A SEMIEMPIRICAL HETERODIODE DESIGN EQUATION As a result of our experiments with a limited range of diode geometries and resistivities. a semi-

Jan 1, 1965

By R. M. Rose, D. P. Ferriss, J. Wulff

Single crystals of tantalum, tungsten, and the binary alloys thereof were grown by electron-beam zone melting and tested in tension between 77° and 373°K. The ductile-to-brittle transition temperature increased sharply with solute concentration, for both tungsten-rich and tantalum-rich alloys; apparently, the maximum transition temperature exists near the 50 pet concentration. Twinning was observed to be a consequence of cleavage-crack propagation. Cleavage occurred on(100)planes, and extensive tearing and "river markings" were present. The onset of brittleness could not be associated with any change in deformation mode, the yield point phenomenon, or the large rise in yield stress with decreasing temperature. Cleavage was observed to initiate at either the specimen surface, or subgrain boundaries. The observation was made that the grain boundaries of Polycrystalline materials are probably even better as nucleation sites for fracture, and are responsible for brittleness at high temperatures and lower solute concentrations than those of the corresponding single crystals. TUNGSTEN and tantalum, the two high-melting neighbors in the third transition period of the periodic table, present striking contrasts. Although both are bee, tungsten has far higher elastic moduli, and the highest ductile-to-brittle transition (DBT) of all the pure metals.' Tantalum, however, is ductile at liquid helium temperatures. Large strain aging and yield point phenomena are observed in tantalum,2,3 but only to a lesser extent in tungsten.4 Tungsten work-hardens at a high rate,5 whereas this effect is negligible in tantalum.' Since the mutual solid solubility of these two metals is complete,7 and no ordering has yet been reported in the binary system, the possibility of depressing tungsten's DBT by tantalum additions was considered. Also, tungsten additions to tantalum could produce hard, high-melting alloys which might be ductile at room temperature. Such alloys offered excellent bases for complex alloy development, particularly with regard to the effect of rhenium on Group VI metals.8"10 In addition, there was the opportunity to examine flow and fracture modes in the vicinity of the DBT, with particular emphasis on the correlation between brittleness and fundamental deformation mechanisms. Myers11 has reported that recrystallized alloys with up to 10 pet W in tantalum are ductile at room temperature, but alloys with 20 pct W could not be swaged at temperatures as high as 500°C. The whole spectrum of Ta-W alloys has been surveyed by Braun, Sedlatschek, and Kiefferl2 using sintered powder compacts. In addition to some physical properties they reported a maximum hardness at about 50 at. pet W, dropping to much lower hardness levels for the pure components. They were able to cold work tantalum-base alloys with as much as 30 pet W and to warm work tungsten-base alloys with up to 20 pet Ta by procedures similar to those used for pure tungsten. EXPERIMENTAL In order to study deformation modes and to keep the impurity concentrations at a minimum, electron-beam zone melting was used to prepare single crystals of high purity. The electron-beam zone melting apparatus is similar to that described by Calverley, Davis, and ever" and incorporates a grid control rectifier to maintain control of emission current. Pure metals were refined by making three zone passes at 4 mm per min up the rod. Alloys were prepared by melting together wire of one constituent on a previously melted rod of the major constituent. Subsequently, two zone passes were made in opposite directions to level the composition after the manner suggested by pfann.14 Purification of the starting materials was accomplished by evaporation of the several impurities, and the degree to which this was accomplished is indicated in the chemical analyses of Table I. The uniformity of composition along a zone levelled rod was within the i 1 pet accuracy of the fluorescent X-ray technique used to determine composition. Crystallographic orientation of the

Jan 1, 1962

By Geo. W. Goetz

The following tables show the analyses of ores from nearly all of the mines which will produce over 10,000 tons of ore each during the season of 1890. There are many small mines now in the course of development, some of which may become large producers. Many of the mines produce several different grades of ore, but the analyses given in the tables are fair averages of ore such as the respective mines can deliver. Most of these analyses were obtained from the agents of the respective ores, and are averages of the season of 1889. One can state positively that over 75 per cent. of all the iron-ores of the Lake Superior district will average over 60 per cent. of metallic iron. During the past 34 years this region has produced about 48,137,421 tons of ore, the different districts contributing about as follows: Marquette District,. 29,754,057 Menominee " .10,415,859 Gogebic " . 6,622,194 Vermilion " . 2,342,991 Miscellaneous,. .. .. 2,320 In the year 1889, the product of all the districts was nearly '1,300,000 tons. The product of the entire region for the season of 1890 may exceed 9,000,000 tons. This large amount of ore is shipped to the lower lake ports, from Escanaba, Marquette, Two Harbors and Gladstone.

Jan 1, 1891

By Walter C. Holmes

IN the recently published book entitled "Man in a Chemical World," by A. Cressy Morrison, the several pages discussing explosives were included in the chapter on "Serving Industry." Such a classification is entirely correct, as blasting explosives function only as a tool for accomplishing certain useful work, a tool which is completely destroyed in one use. Explosives are so important to industry and to modern society, in fact, that it seems impossible to imagine the existence of civilized nations without access to commercial explosives as ready servants. Two main types of explosives are now in use, the low-velocity or deflagrating type, such as black powder, which is adapted for use in coal mining and other applications where a slow, heaving effect is desired, and high explosives of the dynamite type,

Jan 1, 1938

By James P. Kimball

Jan 1, 1885

By H. W. Krotzer

ADOPTION on a commercial scale of electrolytic deposition of metals brought with it the problem of providing an acid-proof cell or tank. Where the electrolyte contained only a dilute solution of sul-furic acid, wooden, tanks with lead linings were gen-erally adopted. There were cases, however, where a lead lining was impractical as a result of the presence of nitric acid in the electrolyte or because of the method of handling the current for deposition. purposes. Wherever lead was unsuitable for this work, asphaltic mastic was used in its place. This material, in addi-tion to possessing acid-proof qualities and being an insulator for electrical current, is also cheaper than lead. The only reason that prevented the common adoption of mastic for all work of this type was that it was still an unknown, unproved. material; while lead, although more costly, could be relied on. There are several electrolytic tank-houses equipped with acid-proof mastic linings now in operation. The first large one was the series tank-house of the Balti-more Copper Co., where the mastic used was composed of natural asphalts and a silica aggregate. These lin¬ings are now seventeen years old and still in service. The next large plant was that of the Chile Exploration Co., at Chuquicamata, Chile, ,and it is with this that this article deals. Another plant of more recent date is that of the Nichols. Copper Co., Laurel Hill, L. I., and specifications for the new electrolytic tank-house of the Union Miniere du Haut Katanga call for mastic lining. It is also being tried out on a smaller scale or for experimental purposes by many of the larger metal-lurgical companies. Thus while mastic linings were adopted originally to meet operating conditions that prohibited the use of lead, they are now in a position to compete successfully with the standard lead linings that are in general use. The Chile Exploration Co. plant, with a total area of over a million square feet, giving satisfactory ser-vice under the most adverse climatic and metallurgical conditions can be truly called the pioneer in this work. ,This article will deal with the development of the acid-proof mastic linings in Chuquicamata from the original experiments begun in 1912 up to and including the final successful installation that has now been in service for a number of years.

Jan 4, 1927

By AIME AIME

A COMMITTEE of the American Railroad Association, consisting of Samuel Rea, president of the Pennsylvania System, Chairman; F. D. Underwood, president of the Erie Railroad; A. T. Dice, president of the Philadelphia & Reading Railroad; E. J. Pearson, president of the New York, New Haven & Hartford Railroad; and C. H. Markham, president of the Illinois Railroad (who was represented at the meeting by J. F. Porterfield of his system), met at the headquarters of the American Institute of Mining and Metallurgical Engineers, New York, on April 6 to assist in the Coal and Coke Committee's attempt to solve the bituminous coal problem. There was a full discussion of the questions of seasonal freight rates and the purchase by the railroads during the slack months of their winter's supply of coal. As the question of fuel supply for the railroads is in the hands of the Railroad Association, as well as the coal operators, it was vital that it should be represented at this important conference. The situation from the point of view of the mine operators was presented very thoroughly. No seasonal rates were considered necessary for the year 1920, and, as this matter requires considerable thought, it will be given thorough study and worked out in detail at a subsequent meeting.

Jan 1, 1920

By William H. Radford

Having worked some rather lorn--grade gravel during the past season at a small profit, I give the actual figures, in the hope that other mining engineers interested in this line of work may be thereby induced to do the same, in order that we may all get more data on this little-ventilated subject. The property here referred to is situated in one of the northern counties of California, where hydraulic mining is still permitted by the courts. The water-right belonging to the mine is a good one, furnishing water during about nine months, whenever there is an average rain-fall, and a fair proportion of the precipitation is in the form of snow. The ditch, about 11 miles in length, is cared for during the rainy months by two men, and during the rest of the year by one; and the water cost last season, delivered at the mine, 0.69 cent per miners' inch. The season commenced in November, 1899, and ended the last of July, 1900. During this time, 655,657 miners' inches (an inch equals 1728 cu. ft. in 24 hours) of water were used for piping, and for sweeping the bed-rock at the end of the season. From actual surveys, this amount of water washed down 1,251,399 cu. yds. of material, consisting of pay-gravel lying on the bed-rock, and varying in thickness from a few inches to 8 ft., and practically barren top-material, consisting of mountain slide, carrying considerable broken rock, clay, and soil. The banks varied in height from 50 to 130 ft., the average height being 63 ft. The grade of the sluices was 7 in. to 12 ft., the boxes being paved with block-riffles 12 in. deep. Long bed-rock cuts extended from the heads of the sluices to within a few feet of the banks, and were kept practically to grade as the work advanced. At first, electric drills were used on this work; hut as it was found that heavy blasting shattered the rock too much, and caused slips, these drills were

Jan 1, 1902

By AIME AIME

WHETHER by the Mohawk Trail, Sound steamer, air plane, railroad or any other route or mode of locomotion, all roads will lead to Boston the week of National Metal Congress, Sept. 21-25. The Institute of Metals and Iron and Steel divisions of the Institute are then to meet jointly at the Hotel Statler, and the American Society for Steel Treating, the American Welding Society, the Society of Automotive Engineers and the Iron and Steel Division of the American Society of Mechanical Engineers present carefully planned programs at their respective sessions. The National Metal Exposition will be held on Commonwealth Pier.

Jan 1, 1931