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By Sharon Brady, Catherine O’Donoghue, John V. Beall, Paul C. Merritt

Between 1950 and 1965, more than 80% of all phosphate rock produced in the world each year was used as fertilizer, either directly applied to the soil or processed into mixed chemical fertilizers. Of the potassium salts produced, 95% followed suit. A variety of uses in industrial chemicals and consumer products absorbed the remaining percentage of each. Future trends in these two commodities will be dominated by what happens to the fertilizer market. Farming is much the same as mining the soil. Plants remove the minerals little by little. Phosphate and potash comprise two of the three primary nutrients removed in this way, the third being nitrogen. Phosphate stimulates early root formation and growth, whereas potash is a salt necessary to root strength.

Jan 10, 1966

By AIME AIME

WHEN "Chief" Buehler in mid-September set out on his official 10,000 mile swing-around-the-circle visiting Local Sections he decided not to tell his audiences how to organize and operate a state geological survey. As the director for 28 years, of the Missouri Bureau of Geology and Mines (which, he concedes, is the best in existence) lie could have done this to good advantage; but he preferred to discuss affairs of the Institute. In 25 speeches made to member and student groups, he dwelt on sonic or all of the following phases of activities. He stressed the vital importance of the Local Sections in providing the opportunity for members to associate under pleasant auspices with others in their profession. The benefits of Institute membership he classified as tangible and intangible. Of the two lie felt that the latter were more important. A man's progress in his profession depends in large measure upon a broad acquaintance and friendship with others. The Institute is incomparably the best medium for meeting fellow engineers. The primary, function of the new enlarged Membership Committee is to obtain a comprehensive list of engineers eligible to be members, always hearing in mind that the standards of membership must not be lowered in any degree. These men are to be invited by individual letter to apply for membership. Whether they become members or not is of less importance; but it is vital that no qualified man should be outside the fold for the reason that membership had never been suggested to him. Dr. Buehler emphasized repeatedly his feeling that the younger man that had never had Institute membership brought specifically to his attention had been cheated:

Jan 1, 1935

By W. W. Stephens, W. J. Kroll, H. P. Holmes

THE only two methods for producing commercial quantities of malleable zirconium, up to now, have been using magnesium reduction of the anhydrous chloride under a neutral gas, and using purification of raw zirconium by the iodide dissociation method on a hot filament. The purity of the metal obtained by the latter process is about the same as that resulting from the chloride reduction, with the exception of the oxygen content, which may be about 0.05 pct lower in the iodide metal. Even traces of oxygen have a strong hardening effect on zirconium. Since, in the iodide process, the impurities, Si, Al, Fe, Ni, and Mg in the raw zirconium used, are carried over, it would appear uneconomical to use this method of refining solely to eliminate the traces of oxygen, unless very soft metal is desired. One important step to improve the iodide method, namely, dissociating pure iodide made from carbide and recycling the iodine, which would change this refining process into a method for extracting zirconium from the ore, has not yet been made. The Bureau of Mines, by using the chloride reduction, wanted to produce quantities of a reasonably pure and malleable metal at low cost for large-scale industrial use. This aim has been achieved, and a pilot plant permitting production of 600 lb of malleable zirconium per week will be described (fig. 1). Briefly, the Bureau of Mines process consists of reducing purified gaseous anhydrous zirconium chloride with fused magnesium under a noble-gas atmosphere. The reaction product, magnesium chloride, and any excess magnesium metal present are removed from the sponge zirconium in the next step by fusion and evaporation in a good vacuum at about 925°C. In this process, care is taken to keep air out of contact with the hot metal, which otherwise would contaminate the product with oxygen and nitrogen. Both these impurities embrittle zirconium even when present in an amount as low as 0.1 pct. A number of previous reports1-3 describe the method and the various improvements that finally led to a workable process. The major steps made were the production of large quantities of carbide, which is the raw material for producing the chloride, its chlorination with reasonable efficiencies, and the elimination of iron trichloride contained in the raw chloride, as well as that of the zirconium oxide which is always present in this product. The physical nature of the anhydrous chloride, which sublimes at 331°C at atmospheric pressure and melts at 420°C under a pressure of 25 atm, made it necessary to provide a special safety device on the purification and reduction vessels in the form of a lead-alloy seal, permitting escape of excess gases if pressure tended to build up. The main difficulties encountered in the reduction and in the following step, salt separation in a vacuum at elevated temperature, were caused by the material from which the reaction pot was constructed—iron. This metal reacts with zirconium at about 940°C with formation of a eutectic. The last step, salt separation by evaporation of the magnesium and magnesium chloride in a vacuum, is quite unconventional and has not been used before on such a scale. It is only due to the improved construction of high-vacuum pumps, especially oil-diffusion pumps, that such a method could be used. The various steps of the Bureau of Mines process, as described in the general outline above, may be summarized as follows: (1) production of the carbide, (2) chlorination of the carbide, (3) purification of the raw chloride, (4) reduction of the pure chloride with fused magnesium, (5) separation of excess magnesium and magnesium chloride in vacuum at elevated temperature, and (6) melting of the sponge obtained. Production of Carbide The arc furnace, described in a previous report,' was improved both to reduce the graphite consumption caused by the burning of the bottom plates and to concentrate the heat in order to obtain better power efficiency. This was achieved by providing the bottom with graphite plates entirely embedded in refractory bricks, the contact with the current being made with three water-cooled copper plugs. Figs. 2 and 3 show the arrangement. The crucible, made

Jan 1, 1951

By Maureen G. Johnson

At least three million ounces of placer gold has been mined from hundreds of deposits in the Southwest since the 1600's. Nevada, the most productive state, produced about 1,700,000 oz. Most of the placers are in accumulations of unsorted, coarse, angular gravel in gullies, dry washes, and on hill- sides. The gold is mixed with debris from the adjacent bedrock and is typically concentrated at or near bedrock or on clay layers or caliche-cemented gravels above bedrock. The most extensive and productive placers are thick accumulations of debris in well-defined stream or gully channels, in alluvial fans at the edges of the range fronts, or as thick residuum on hillsides. With very few exceptions, the gold has been transported only a very short distance from the source. Numerous small high-grade gold-quartz veinlets, rather than single large lode deposits, are by far the most common source of placer gold. Most placer mining consisted of small-scale one-or two-man operations using rockers, pans, and sluices when water was available and dry-washing machines when it was not. Where gravels were deep the miner would dig shafts to bedrock and drift along the paystreak. Large-scale operations in the major districts utilized floating or stationary dredges or, more rarely, hydraulicking to mine extensive deposits. An adequate supply of water for efficient concentration of gold has always been a major problem in the Southwest. To overcome this problem, difficult and sometimes ingenious techniques were used-pipelines to carry water for miles to the placer area were constructed, or gravel was hauled to central washing plants where water was available; numerous designs of dry-washing machines were invented. In some districts, attempts to mine the gravels by large- scale operations failed because the gravels were too wet for dry concentration methods, and no water was available for wet methods; or, when water was available, the gravels were too porous to retain sufficient water in the dredging pond.

Jan 3, 1974

By W. L. McMorris, Shiou-Chuan Sun

The Convertol process was first described in Ger- many by Muschenborn1 in 1952. In the U. S. Fraser2 reported this new process in 1953, and Brisse and McMorris-resented the results of a Convertol pilot plant at the Alpheus preparation plant in Gary, W. Va., illustrating the mechanics of the process by a series of sketches. The purpose of the present investigation was threefold: 1) to determine the relative effectiveness of various oils and hydrocarbons for recovering coal by the Convertol process, 2) to ascertain the behavior of coal pulps in this process under various operational conditions, and 3) to compare Convertol with flotation in the recovery of fine coals.

Jan 11, 1959

By Marlin J. Veesaert

Urban quarries offer one of the greatest opportunities for profit in nonmetallic mining with limited financial risk-if properly evaluated, planned and developed to meet market needs. Location, with respect to market, is the prime consideration. Geologic considerations and quality of rock are nearly as important. Cost factors and return on investment (ROI) are the principal financial considerations.

Jan 8, 1979

By A. S. Richardson

THE design of mine airways receives, in general, very little engineering treatment. To a large extent this is, of course, due to the fact that information upon which to base calculations is seldom available in definite form. In many mines the extent of the workable deposits may not be known at the time an air course is planned, and the length of service is indeterminable. Volume of air required for ventilation may also increase with extension of the life of a property, and natural obstacles, such as heavy ground, often place limitations upon the size of opening that can be maintained. Perhaps a majority of the shafts used in ventilation of metal mines were originally intended as hoisting shafts, and many of the tunnels and cross-cuts similarly used, were also designed as haulage ways or for other operating purposes. Even when a shaft is sunk solely for ventilation, custom usually dictates a size and shape consistent with the type commonly used for ordinary operations, because experience has demonstrated it can be excavated and maintained. In fact it may not be very far wrong to say most ventilation openings were never made with any consideration as to economic design for such use. When an air course is required to pass air between different parts of mine workings under a fixed pressure, the size of opening required for a given volume of flow, is, of course, determined by the resistance factor of the air course. It is then impossible to proportion the opening with reference to economics of power consumption, and this paper is limited to the design of openings where ventilation pressure or power consumption may be varied for economic advantage.

Jan 2, 1926

By J. B. Shannon, J. D. Grenia

The Buick Mine is a joint venture of American Metals Climax, Inc. and Homestake Mining Company located 120 miles by road southwest of St. Louis, near the village of Boss, in the `New Missouri Lead Belt'. Since start-up in 1969, over four million tons of lead-zinc ore have been mined and milled at Buick. Situated 1100 ft below the surface at an elevation 270 ft above sea level, the flat lying sinuous orebodies are up to 250 ft wide, 85 ft high and several thousand feet long. Mineralization is galena, sphalerite and chalcopyrite in dolomite.

Jan 7, 1973

F. E. BACHMAN, Port Henry, N. Y. (written discussion*).-Experi-ments with titaniferous ores found in Essex County, New York, made by the MacIntyre Iron Co. in 1914, showed' that titaniferous concentrates are reduced in the furnace with no greater, and probably with less, expenditure of heat, and consequently of fuel, than non-titaniferous mag-netites; and as a greater proportion of their oxygen is removed by carbon monoxide than is the case with non-titaniferous magnetites, a lower fuel consumption for the reduction of iron may be expected. After the furnace was blown out at the end of the experiment, the formation in the hearth was found to be abnormal. The brickwork was replaced, entirely around the furnace, by a layer which at -the tuyere circle was made up of cinder, fine carbon, and coke; the coke, however, gradually disappeared toward the bottom, being replaced by cinder and graphite. The usual salamander of graphite and iron was missing. The material left in the hearth seemed to be cinder that had not drained from the last cast; its composition, though, would indicate that it was in the furnace previous to the taking off of the titaniferous ore. At first, this material was thought to be blast-furnace cinder mixed with less iron and graphite than is normal; but an examination showed it to be made up of cinder with small masses of iron and graphite. There were also patches of a steel-gray material having a metallic luster; a microscope showed these patches to be made up of black metallic crystals interlacing white crystals.

Jan 11, 1919

NAME AND OBJECT. SEc. 1. This Institute is incorporated under the Membership Corporations law of the State of New York ; its corporate name is American Institute of Mining Engineers; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II. MEMBERS. SEC. 1. The membership of the Institute shall comprise four classes, namely 1. Members ; 2. Honorary Members ; 3. Associates ; 4. Junior Members. All members shall be equally entitled to the privileges of membership, except¬ing that Honorary Members, Junior Members, and Members and Associates whose residences shall be outside of the United States, Mexico, and Canada shall not be entitled to vote. Members and Associates residing within the United States of America, Mexico, and Canada, and not in arrears for dues, shall be entitled to vote in person at the meetings of the Institute, or, as hereinafter provided for, by letter ballot. SEC. 2. The following classes of persons shall be eligible for membership in the Institute, namely : as Members, all professional mining . engineers, geologists, metallurgists, or chemists, and all persons actively engaged in mining and metal¬lurgical engineering, geology, or chemistry ; as Associates, all persons desirous of being connected with the Institute who in the opinion of the Board of Directors are suitable.

Jan 1, 1923

By J. J. Kanter

A. I. Blank.*-—Mr. Kanter has spoken of failures from causes other than creep itself in metals that are subjected to creep stresses. Would it be possible for the author to enlarge on this very important matter of "cataclysmic types of failures? " J. J. Kanter.—Of course, it is always a delicate matter to discuss specific failures. I would prefer to keep the present discussion on fundamentals and principles. H. L. Burghof.*—Mr. Kanter, I should like to ask what you consider the responsibility of the designer in avoiding stress concentrations that would lead to these types of failures? J. J. Kanter.—lt was my feeling in looking over the papers of this symposium that they were significantly lacking in consideration of what happens to the metals when strained under conditions that lead to rupture. Often creep tests are run that produce only a fractional percentage of the deformation, in several thousand hours. That kind of information gives the designer no assurance whatever that cracks will not result in his structure at points where stress concentrations, and therefore deformation concentrations, exist. I think anyone in this day and age who presents a paper on creep should incorporate with those studies a thorough investigation of creep rupture if it is expected to make an impression upon the design engineer.

Jan 1, 1945

By W. N. Page

The Red-Ash colliery was the scene, March 6, 1900, of an explosion by which some fifty men were killed or wounded, and much property was injured or destroyed. On March 19th, the earliest date at which entrance was practicable, I examined the mine with the view of determining the extent, cause and point of origin of the explosion, and with the permission of Mr. F. Howald, the manager, and the owners of the property, for whom the examination was made, I present in this paper some results of that examination, comprising the essential portions of my report to them. Location and Plan of the Mine. The Red-Ash colliery, situated on the south side of New river, next below the Rush Run mine, with which the underground workings are connected, is a drift-mine, the entrance to which is on a slope, about 500 ft. above the river. (Fig. 1 is a plan of the workings, in which the points where human bodies were found are designated by numbers.)

Jan 1, 1901

By Thomas W. Gibson

THE Province of Ontario in recent years has come strongly to the front as a producer of metals, especially nickel, copper, silver, and now gold. Of the last named, the output for 1922 was in the neighborhood of $20,000,000. The law governing the mining industry in a community where such develop-ments are taking place will be of interest, therefore, in other places where mining laws are up for revision The first mining of importance done in this province was for copper on the north shore of Lake Huron, where the Bruce mines were opened in 1846. These deposits of copper sulfides, notwithstanding the remoteness from markets and the cost of transportation, were vigorously worked for 12 or 15 years and also intermittently later, but the active career of the mines came to an end in 1875. From first to last, a little less than 10,000 tons of copper was produced, valued at $3,300,000. All the product was shipped to England as dressed ore, contain-ing up to 13 per cent. of the metal. In. 1866, a rich pocket of gold was found on the Richardson farm near Madoc, Hastings County, but was not followed by further discoveries of a like kind and in time the excitement it caused died away. Rich silver ore was found in 1868 on Silver Islet in Lake Superior, a speck of land not larger than a good-sized ball-room. The assemblage of minerals here was practically the same as that at Cobalt, discovered 35 years later, namely, native silver, cobalt, nickel and arsenic; in addition, there was considerable argentite, which has always been scarce at Cobalt. In all, the silver produced amounted to about $3,500,000. The belief persisted that the deposit was not mined out, and in the summer of 1922, some rich ore was extracted from the roof, perilously near the bottom of Lake Superior.

Jan 2, 1923

By Freeman Bishop

The Bureau of Mines is working on a long-term program to completely revolutionize mining-to create a mine-systems technology that integrates the need to recover minerals at low cost under safe and healthful working conditions while protecting the environment. Everyone should be brought into the planning process preceding each new mining development, the Interior Department urges, and Assistant Secretary Hollis M. Dole seems determined to push this kind of systems approach with everything he can move.

Jan 1, 1970

By Leon McCulloch

WIIen clean iron and metallic zinc dust, protected from the air, arc heated below the melting point of zinc, the iron takes on a coating that has excellent protective value. This coating is a brittle alloy of zinc and iron, and the process is called sherardizing. Although the zinc particlcs are covered with oxide and cannot touch the iron, an extremcly small amount of the zinc vaporizes and the vapor, reaching the iron, alloys with it. Other zinc then vaporizes to replace that which has been removed from the atmosphere. This process continues indefinitely at a decreasing rate, for the coating already formed permits zinc to diffuse through it to combine with the iron beneath. In this way, the coating grows outward from the surface of the iron, as the bark grows from a tree. The method of growth was clcarly seen while sherardizing small cubes of cast iron, at about 450" C., in a srnall glass-stoppcrcd bottle enclosed in a rotating drum. The dust contained about 3 per cent. iron, which prevented caking, and coatings % in. thick were grown in a few hours. After a heavy layer had been formed, the cubes mere again treated for a shorter time. The layer last formed was seen to lie next to the iron, instead of at the outer surface, showing that the growth was from the surface of the iron outward. The coatings split at the edges and corners, leaving the iron exposed there. Flakes of graphite from the iron were lifted upward and embedded in the coatings. The composition of sherardized coatings varies from the outer surface inward, as would be expected from the mode of growth. That is, the iron content increases slowly at first, then more rapidly as the iron is approached. At the surface the least amount of iron possible is 6 per cent., as the experiments described below have shown. A study was made of the effect of iron in zinc dust on the proccss and on the resulting coatings. Glass bulbs, holding the small pieces to be sherardized, together with enough zinc dust to make them two-thirds full, were heated in a small, rotating electrically heated and controlled furnacc. The bulbs had 6-in. (15 cm.) necks, of 96-in. (9.Fj mm.) tubing, plugged

Jan 1, 1923

By Leon McCulloch

WIIen clean iron and metallic zinc dust, protected from the air, arc heated below the melting point of zinc, the iron takes on a coating that has excellent protective value. This coating is a brittle alloy of zinc and iron, and the process is called sherardizing. Although the zinc particlcs are covered with oxide and cannot touch the iron, an extremcly small amount of the zinc vaporizes and the vapor, reaching the iron, alloys with it. Other zinc then vaporizes to replace that which has been removed from the atmosphere. This process continues indefinitely at a decreasing rate, for the coating already formed permits zinc to diffuse through it to combine with the iron beneath. In this way, the coating grows outward from the surface of the iron, as the bark grows from a tree. The method of growth was clcarly seen while sherardizing small cubes of cast iron, at about 450" C., in a srnall glass-stoppcrcd bottle enclosed in a rotating drum. The dust contained about 3 per cent. iron, which prevented caking, and coatings % in. thick were grown in a few hours. After a heavy layer had been formed, the cubes mere again treated for a shorter time. The layer last formed was seen to lie next to the iron, instead of at the outer surface, showing that the growth was from the surface of the iron outward. The coatings split at the edges and corners, leaving the iron exposed there. Flakes of graphite from the iron were lifted upward and embedded in the coatings. The composition of sherardized coatings varies from the outer surface inward, as would be expected from the mode of growth. That is, the iron content increases slowly at first, then more rapidly as the iron is approached. At the surface the least amount of iron possible is 6 per cent., as the experiments described below have shown. A study was made of the effect of iron in zinc dust on the proccss and on the resulting coatings. Glass bulbs, holding the small pieces to be sherardized, together with enough zinc dust to make them two-thirds full, were heated in a small, rotating electrically heated and controlled furnacc. The bulbs had 6-in. (15 cm.) necks, of 96-in. (9.Fj mm.) tubing, plugged

Jan 1, 1923

By R. B. Haagensen, E. Martinez, V. Kudryk

The sample under investigation contained approximately 16% BaSO, and was 80% -325 mesh. Established methods for floating barite did not produce concentrates of satisfactory grade or barite recovery because of low barite content and the presence of 6% calcite in the feed. By using a new long-chain sulfosuccinamate collector in combination with relatively high concentrations of sodium silicate, a barite concentrate was produced that would be acceptable as an oil-drilling mud using a simple rougher-cleaner circuit. No desliming of the fine-ground feed was necessary. Barite recovery was over 80% and the concentrate produced had a specific gravity higher than 4.3. During the course of the investigation, a procedure was developed to obtain semiquantitative determinations of barite, calcite, quartz, and feldspar in test samples using an infrared spectrophotometer. Samples were also analyzed in a thermobalance for determination of the calcite content. The use of these instruments made it possible to obtain quick mineralogical assays and proved to be of invaluable assistance in guiding the flotation testing.

Jan 1, 1976

By L. G. Graper, E. L. Ramsey

THE present program of increased production of armament and lend-lease material for mechanized war has created a problem for the shops that must do the machining. They have naturally turned to the steel producers to provide them with a steel that can be accurately machined with the greatest possible speed. The adding of sulphur to steel as an aid to machinability has long been practiced; however, it may cause red shortness in rolling and may result in billets with seams and cracks, which must be removed before rolling can be continued. This conditioning of billets slows down production and adds to the cost of making steel. Experience with various grades of sulphur steel made to different specifications has shown that Bessemer sulphur steels roll better than similar grades made in the open hearth, and also that low-carbon steels that are open or semi-killed as tapped roll better than completely deoxidized or killed steels. This has led to the belief that oxygen plays an important part in the rolling qualities of sulphur-bearing steels. It is generally held that the red shortness of sulphur steels is due to the low melting point of the sulphide compounds that separate out at the grain boundaries when the steel solidifies. At the rolling temperature of steel these sulphide compounds melt and cause cracking. ADDING SULPHUR AS A SULPHITE These difficulties can be avoided if sulphur is introduced into the steel by means of an anhydrous sulphite, such as sodium sulphite or sodium bisulphite, which-upon decomposition-forms sulphur dioxide. It is assumed that, in this case, the oxygen of the sulphur dioxide forms part of the sulphide inclusions in the steel, and raises their solidification temperature enough so that the formation in the steel of a low-melting eutectic is prevented. The result is the prevention of hot shortness and a more uniform distribution of inclusions. Fig, I shows photomicrographs of steels made with sulphur, while Fig, 2 illustrates the structure of steels made with sodium bisulphite. These samples were cut from the steels as cast-that is, before rolling and were polished and lightly etched to bring out the grain boundaries. Fig. I shows that sulphide inclusions segregate more or less at the grain boundaries, and it can be seen how the continuity of these low-melting inclusions would cause red shortness. Fig. 2 shows that the sulphide inclusions are more or less uniformly distributed throughout the matrix. This arrangement of inclusions has no apparent effect on the rolling qualities of a steel. This statement has been substantiated by the observation of the rolling of over 6000 tons of steel made with a sulphite addition. RESULTS As stated before, the sulphur dioxide is added to steel by means of the decompcsi-

Jan 1, 1942

By E. S. Moore

THE Kolar gold field has been for a long time the most important gold-producing area of India. It is situated in the State of Mysore, southern India, and not far from the City of Bangalore. The productive field is about 3 miles long and in it a gold-bearing quartz vein varying in width from 1 in. to over 10 ft. is worked. The vein carries high values to great depths and many of the mines have paid large dividends. GEOLOGICAL FORMATIONS IN THE MOLAR REGION The rocks of the Molar region are pre-Cambrian in age and bear a close resemblance to some of the pre-Cambrian formations of America. The oldest rocks seen are basic lavas, now mostly altered to hornblende-schists, with which is associated some banded iron-formation; these rocks are similar to the Keewatin schists and iron-formation in the Lake Superior region. The schist is cut by the gold-bearing quartz vein. In certain parts of the area there is also a conglomerate containing pebbles of granite, jasper,, and schist. The matrix resembles a horn-blende-schist and is intruded by small granite dikes, which in some cases have been pinched off by squeezing of the rock. This has led Dr. W. H. Smeeth, Chief Inspector of Mines of Mysore, to whom the writer is greatly indebted for information regarding this area and for his hospi-tality while visiting the field, to regard this conglomerate as a breccia due to crushing of granite dikes in the schist. Dr. J. W. Evans has regarded the conglomerate as probably a squeezed glacial boulder clay. From analogy with pre-Cambrian conglomerates in America, the writer regards it as a metamorphosed rock similar to our basal Huronian conglomerate. However, the main bearing which it has upon the problem under discussion is the apparent fact that it is younger than the schist

Jan 3, 1918

By Edgar G. Tuttle

The accompanying figures show the arrangement of a twocompartment excentric jig fitted with adjustable and automatic discharges for drawing oft' the lower product obtained in jigging minerals, ores, coal, etc., which is designed to remove or separate more effectively the materials treated, as they travel over the jig from the receiving- to the discharge-points.

Jan 1, 1897