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By Fred Chappell

Pyrophyllite, a hydrous aluminum silicate, physically similar to talc, receives its name from the Greek word Pyr, for fire and phyllite, a rock or stone. Firestone refers to its first recorded use as firestones or hearthstones. Composition and Properties Pyrophyllite is an aluminum silicate A12O34SiO2H2O (alumina 28.3 pct, silica 66.7 [ ] pct, water 5.0 pct) (Table 1). Vanderbilt1 gives pH value of pyrophyllite as 5.6 to 8.4. Pyrophyllite is usually white or cream, though it may be found in shades of pale green, pale yellow, buff or light gray, and in darker shades and other colors principally due to oxidation of contained iron minerals. It is opaque to translucent in thin sections. Its hardness is 1 to 2 in the Mohs scale. Its specific gravity is 2.8 to 2.9. Its luster is pearly to dull; it is recognized chiefly by its micaceous structure and cleavage, and its soft greasy feel. Two other varieties occur, one in which there are radiated needles in the crystalline form, and there is also a massive homogeneous structure found. Fine grinding reduces pyrophyllite to fiat plates or scales but aggregates of minute foliated plates may be formed.1 Distribution of Deposits Pyrophyllite is found in metamorphic rocks throughout the world but it is only in comparatively recent years that it has assumed much commercial importance. The principal

Jan 1, 1960

By W. A. Vine

WHEN a hole is made in a stressed solid, such as rock pierced by mine openings, equilibrium of the solid is destroyed. To re-establish that equilibrium the stress condition in the rock surrounding the opening becomes rearranged. This rearrangement may or may not develop local stresses in the vicinity of the opening which exceed the elastic strength of the rock. Since stability of the opening depends, therefore, on the strength of the naturally occurring rock surrounding the opening, this rock is an engineering material of construction, and all rock affected by the associated opening or system of open- ings may be considered a structure. The term invert is chosen to describe the formation of the structure —built from the inside, as it were, and a consequence of mining rather than an entity built for a purpose. By definition, an invert structure is formed when openings are made underground and is composed of that material on the solid side of a rock-air interface wherein the stress condition is affected by the associated opening or system of openings. The shape of an invert structure is never clearly defined; the skin of the structure may be mapped, and even described, but the boundary of the structure within the solid rock mass must be arbitrarily set. The name geomechanics is proposed to describe a branch of scientific knowledge which will encompass principles and working hypotheses for behavior and design of invert structures. It is foreseen that study

Jan 1, 1956

By Joe L. Ratigan

INTRODUCTION Rock mechanics engineers are seldom concerned with obtaining the tensile or fracture strength of brittle rock at low mean stresses. The reason for this is two fold. Firstly, the behavior of many excavations in brittle rock is controlled by the inherent discontinuities in the rock mass. Because of the jointing and faulting, tensile strength is usually taken to be negligible. The second reason that tensile strength is seldom obtained in the laboratory is that the technology of utilizing this strength measure in design is undeveloped. Despite the fact that tensile strength of brittle rock is often ignored, there are a number of applications in rock mechanics wherein the knowledge of tensile strength is of fundamental importance. The apparent tensile strength must be known in a hydraulic fracture experiment if the state of in situ stress is to be determined from the initiation of the hydraulically induced fracture. In certain underground situations, the apparent tensile strength of intact rock beams defined by jointing or bedding planes is important in determining required rock bolting. Numerous other situations require a knowledge of apparent tensile strength including such high technology uses of underground space as geothermal energy extraction and LPG storage. Three observations are invariably made when intact rock samples are taken into the laboratory and tested to determine tensile strength. (1) The apparent tensile strength depends on the sample size (the 1 arger the specimen, the lower the tensile strength)

Jan 1, 1982

By Reamy Joyce

CONDITIONS in underground mining are so variable that in approach-ing the problem of the economies effected by the use of pressure-treated mine ties and mine timbers, it is necessary to secure specific data for each mine. Facts must first be dug out to show the service life of untreated timber and the reason for its failure. Generally speaking, decay is the usual cause of failure, but in some mines mechanical destruction is an important factor. Occasionally the two causes combine to produce fail-ures, and it is difficult to determine positively which factor is responsible. In making comparisons, it is always necessary to start with the cost in place and for this reason there must be accurate information covering the labor cost of installation and the labor cost of renewals. When treated timber is used, it is necessary to know the specifications for the treating process, whether the timber was painted, dipped, treated open tank, or impregnated under pressure according to standard specifica-tions. It is also necessary to know the preservative used and the amount of the preservative that was retained by the timber after treatment. It is also well to know whether the timber was thoroughly air-seasoned before treatment or was green at the time it was treated. The kind of timber available, both untreated and treated, must be known and all of the factors listed above must be taken into consideration in the study of any problem.

Jan 1, 1939

By C Gunther

Mining examinations are of several kinds and the scope of the investigation depends in each case upon the purpose for which the examination is made. A formal examination of a developed mine is an expensive undertaking; from one to several months are allowed for the work according to the size of the property; many samples are taken; investigation is made of the geological features, including, perhaps, a topographical and geological survey of the surface; the metallurgical treatment of the ore is studied; finally, a determination of costs is demanded. Formal examinations are made for prospective purchasers or as a basis for the consolidation of several properties, and occasionally, in the owner's behalf, to verify the work of resident engineers, or to determine the readiness of a mine for equipment and the kind and capacity of equipment it shall receive. A formal examination of a mine should not be undertaken until a preliminary examination has shown that it is justified. It is regrettable that some engineers are in the habit of prosecuting long and exhaustive examinations of properties whose lack of merit should be, and perhaps is, apparent from the start, or of continuing their investigation long after an unfavorable result is seen to be inevitable. This wasting of a client's money is a species of trickery difficult to prove, and therefore the more contemptible. Preliminary examinations are precisely what the term implies, and are undertaken to determine the advisability of making

Jan 1, 1932

Mining examinations are of several kinds and the scope of the investigation depends in each case upon the purpose for which the examination is made. A formal examination of a developed mine is an expensive undertaking; from one to several months are allowed for the work according to the size of the property; many samples are taken; investigation is made of the geological features, including, perhaps, a topographical and geological survey of the surface; the metallurgical treatment of the ore is studied; finally, a determination of costs is demanded. Formal examinations are made for prospective purchasers or as a basis for the consolidation of several properties, and occasionally, in the owner's behalf, to verify the work of resident engineers, or to determine the readiness of a mine for equipment and the kind and capacity of equipment it shall receive. A formal examination of a mine should not be undertaken until a preliminary examination has shown that it is justified. It is regrettable that some engineers are in the habit of prosecuting long and exhaustive examinations of properties whose lack of merit should be, and perhaps is, apparent from the start, or of continuing their investigation long after an unfavorable result is seen to be inevitable. This wasting of a client's money is a species of trickery difficult to prove, and therefore the more contemptible. Preliminary examinations are precisely what the term implies, and are undertaken to determine the advisability of making

Jan 1, 1932

By Allen Rogers

THERE are few natural monopolies comparable with the nitrate industry. Perhaps the only other one is, curiously enough, also an essential fertilizer material, viz., potash, of which the Germans have heretofore held practically a-monopoly due to the existence in their territory of the most important known deposits of potash salts. And although nitrates in minute amounts are found in many desert regions, the only deposits callable of being worked commercially exist in Chile. Combined nitrogen in the oxidized form is an essential for plant life. Nature provides it mainly through the agency of nitrogen-fixing bacteria. But where lands are cropped artificially this supply is too small; and gradually the nitrogen supply becomes exhausted. In order to continue farming, it is necessary to furnish a supply of nitrogenous plant food, and this is clone by putting on various substances containing combined nitrogen. These consist of various animal wastes, ammonium sulphate, the ammonia of which is obtained in the destructive distillation of coal, and Chile saltpeter. The latter is immediately available as a plant food, the nitrogen being in the required form. The other substances must oxidize before they are available. Besides its use as a fertilizer, Chile saltpeter is the source from which the bulk of the nitric acid of commerce is derived. The use of nitric acid in the manufacture of almost, all modern explosives is, of course, well known.

Jan 2, 1918

Because common salt, sodium chloride, is necessary to all animal and much plant life, it is probably the most widely used of all mineral commodities, except for water. Nevertheless, of the total salt consumed, only 7% is used for food, including animal food. Two-thirds of the total is used as chemical raw material, principally for making such basic chemicals as chlorine, caustic soda, and soda ash. Other uses are for road thawing (16%) and water softening. Some 162.5 million tons of salt were used, worldwide, in 1972 (Table 15.4F.1). Production is from bedded salt deposits, salt domes, and evaporation of brines, including solar evaporation of seawater. Production is worldwide from at least 20 countries, of which the United States, China, USSR, the United Kingdom, and West Germany are the leaders. Consumption increases about 7 % annually. Reserves are plentiful: Other important sodium salts are soda ash (sodium carbonate) and salt cake (sodium sulfate). Soda ash comes mainly from the Solvay process (70% ) , which uses salt, limestone, and ammonia as raw materials. A large and growing portion of United States production is from mining large bedded deposits of trona, a natural hydrated sodium carbonate and bicarbonate found in Wyoming, and from brine evaporation in California. Soda ash is used for glassmaking, phenol, soap, detergents, and bleaches. Half of the United States salt cake used is a byproduct from rayon manufacturing. The other half comes from brines and playa lakes in California, Texas, and Wyoming. Salt cake is used mainly for papermaking. ACKNOWLEDGMENT Appreciation is expressed to William B. Dickson, president, Salt Institute. [ ]

Jan 1, 1976

By R. W. Titshall

WHAT IS SAMPLING? We are all involved in sampling almost every day of our lives, by tasting, feeling, or smelling. Most raw materials, food products or manufactured items are sampled several times at various stages of the production process before a commodity of suitable quality can be produced. Data obtained from sampling is used in establishing price, quality control, allocating production costs, or overall process efficiency. The area of sampling outlined in this article is the collection of a small quantity of material from large continuous bulk flows of solids and slurries. The concern in obtaining the sample is that the material obtained is truly representative of the main flow in every respect. The methods and equipment outlined are for the collection of a manageable sample. The sample has to be analyzed in a laboratory to determine its characteristics and compliance to set standards. SELECTING A SAMPLING SYSTEM When selecting a sampling system, it is essential to define the requirements, as to what the actual sample obtained will be used for and what degree of precision is required. Determine whether or not the system has to comply with any set standards such as A.S.T.M. (American Society for Testing and Materials) which have established methods for collection of a gross sample of coal. Sampling which is done for in-plant or process control is not generally governed by set procedures, but similar care should be taken during the selection process so that when the equipment is put into service it will operate reliably and produce a sample which is truly representative of the total material lot or consignment.

Jan 1, 1982

By R. Pakalnis, J. P. Savely, R. D. Call

A simple and inexpensive clay imprint core orienting device has been developed by Dr. R. D. Call. It has a minimum of moving parts, is durable and easily used by drillers, and adds only 15 minutes to a core run. Conventional wire-line drilling and a drill hole inclined 30° to 60° from the horizontal plane are required. The device will not operate in a vertical hole. The orientor is an eccentrically weighted downhole device which can be constructed in a mine shop from an old inner core barrel and lead. Modeling clay is packed in the core lifter case, which is screwed on the downhole end of the orientor. A clay imprint of the bottom of the hole is taken after each coring run. This imprint is matched to the top of the succeeding core run, the drill core is pieced together, and a reference line representing the drill hole is scribed on each core. Fracture attitudes are measured relative to the reference line and the core axis. On recent drilling projects, tests for imprint reproducibility were conducted. The results of these tests show an average variation of f3" in location of the scribed reference line between imprints. Comparisons of surface mapping data with oriented core data are good. It is rare that the entire length of drill core in intensely fractured zones can be oriented because it is impossible to piece the core together. However, if a triple tube set-up is used, a modification in the scribing procedure can result in a good statistical sampling of the fracture population. Attitudes of major structures have been oriented with this technique.

Jan 1, 1983

By Frank F. Aplan

INTRODUCTION Coal is a solid, combustible mineral substance resulting from the degradation and alteration of vegetable matter largely in the absence of air. In this natural process of coalification, some non-combustible mineral matter is always associated with the combustible material. Coal preparation or cleaning is the process of removing this inert mineral matter from the coal. Preparation is highly successful in removing the large fragments of inert material, but is not very effective in removing the fine inorganic mineral matter intimately associated with the coal. Of the 600 million tons of coal produced in the United States every year, approximately one-half is produced by coal cleaning methods (1). The bulk of this tonnage is cleaned by coarse or intermediate gravity preparation methods (5 inches to 28 mesh, Tyler). Fine cleaning, say, -28 mesh, is done by shaking tables, washing cyclones, and flotation, or, until recently, the fines were either incorporated into the clean coal or simply discarded--not infrequently, the latter. In 1972, only 13 million tons of raw coal were cleaned by flotation in the United States, and from this 8.4 million tons of clean coal were produced (1). The percentage of clean coal produced by flotation in Europe (England, West Germany, Poland, U.S.S.R., etc.) is substantially higher. However, coal flotation has grown rapidly in the United States from only a few plants in 1950 to 31 in 1960 (2) and 66 in 1970 (1). Virtually all new preparation plants incorporate flotation into their basic flowsheet. The essential difference between ore and coal flotation is that for ores the entire tonnage is ground to flotation size, whereas for coal

Jan 1, 1976

By R. S. Archer

The proper representation of equilibria involving graphitic carbon in the constitutional diagram of the iron-carbon system is admittedly an unsolved problem, the complete solution of which will probably require the establishment of more experimental evidence than is at this time available. The object of this paper is to present the author's observations on some of the phenomena in question and his interpretation of this and other recorded evidence. The chief of the recently disputed questions upon which the author has experimental evidence concerns the occurrence of graphitization at temperatures below the Al point. In a paper1 presented at the September, 1919, meeting of this Institute, the following is found: "the results given would seem to indicate that the graphite eutectoid lies at a smaller value of carbon content than has been previously supposed. At least this is true unless there is either a marked formation of graphite eutectoid at these rates of cooling, or a decomposition of pearlite into graphite, both rather unlikely suppositions, but not impossible ones." In a discussion of this paper, H. A. Schwartz2 takes the position that the possibility of graphitization occurring below the A1 point is an open question, but that complete graphitization (to less than 0.10 per cent, combined carbon) commonly occurs above this temperature. Another opinion from the malleable castings industry is found in a recent paper3 by Touceda: "Also the carbide of iron can be broken up into its two soft constituents at the temperature referred to. This temperature is called the critical temperature, or critical range, and for air-furnace hard-iron castings it is in the vicinity of 1440" F. It is the

Jan 1, 1922

By R. S. Archer

The proper representation of equilibria involving graphitic carbon in the constitutional diagram of the iron-carbon system is admittedly an unsolved problem, the complete solution of which will probably require the establishment of more experimental evidence than is at this time available. The object of this paper is to present the author's observations on some of the phenomena in question and his interpretation of this and other recorded evidence. The chief of the recently disputed questions upon which the author has experimental evidence concerns the occurrence of graphitization at temperatures below the Al point. In a paper1 presented at the September, 1919, meeting of this Institute, the following is found: "the results given would seem to indicate that the graphite eutectoid lies at a smaller value of carbon content than has been previously supposed. At least this is true unless there is either a marked formation of graphite eutectoid at these rates of cooling, or a decomposition of pearlite into graphite, both rather unlikely suppositions, but not impossible ones." In a discussion of this paper, H. A. Schwartz2 takes the position that the possibility of graphitization occurring below the A1 point is an open question, but that complete graphitization (to less than 0.10 per cent, combined carbon) commonly occurs above this temperature. Another opinion from the malleable castings industry is found in a recent paper3 by Touceda: "Also the carbide of iron can be broken up into its two soft constituents at the temperature referred to. This temperature is called the critical temperature, or critical range, and for air-furnace hard-iron castings it is in the vicinity of 1440" F. It is the

Jan 1, 1922

By W. H. Bassett, J. C. Bradley

In considering the effects of reducing gases on hot solid copper the following conclusions have been reached. (I) Depth of deoxidation of copper heated in reducing gas is grealer the smaller the amount of cuprous oxide originally present in the copper, the range studied being from 0.015 to 0.136 per cent. oxygen. It is suggested that the reason for this diflerence in depth of deoxidation is thai, when the copper is low in cuprous oxide, the reducing gas is diluted less by the gas that is formed in the reaction than when the copper is high in cuprous oxide; and the greater the concentration of the reducing gas the deeper the deoxidation. (2) The rate of deoxidation is much more rapid at the beginning of exposure than at the end, a condition especially noticeable at temperatures around 900" C.; that is, deoxidaion is retarded as the depth penetrated by the reducing gas increases. (3) Within the accuracy of the experiments arsenic in copper up to 0.5 per cent. has no tendency to increase or decrease the action of a reducing gas on the cuprous oxide presenx in the copper. In 1912 pieces of 0.365-in. hard copper rod 1/2 in. long were heated in a porcelain tube in an electric furnace, while illuminating gas was passed through. An approximate analysis of this gas is: Hydrogen 38 per cent., carbon monoxide 30 per cent., illuminants 13 per cent., methane 10 per cent., ethane 3 per cent., carbon dioxide 3 per cent., nitrogen 2 per cent., oxygen 0.4 per cent. After heating for various lengths of time at various temperatures, samples were quenched

Jan 1, 1926

1. What Effect Has Sulfur Or Vanadium (In The Oil) On The Steel With Your Burner? 2. Also, what is the decibel rating on the floor when your burner is on? AUTHORS' REPLY 1. There is no effect. 2. The decibel rating is 98-99 decibels.

Jan 1, 1972

By James Ruddy

THE medical program of the Climax Molybdenum Co. is under the supervision of the department of industrial medicine of the University of Colorado, of which James J. Waring, professor of medicine at the University Medical School, is director. Dr. Waring is consultant and direct supervisor of both the hospital and industrial medical department at Climax. At Climax the program is in charge of the medical director and the associate physician, Dr. Galen M. Hover. The hospital at Climax is completely equipped with all that is necessary for the practice of scientific medicine and surgery. Only graduate registered nurses with experience in industrial medicine are employed. Being only a few hundred yards from the portal of the mine. acci-

Jan 1, 1946

By AIME AIME

THIS year's Chairman of the Institute of Metals Division is a relatively rare phenomenon in the metallurgical profession; he is an expert historian of metallurgy, he is a confirmed collector and student of old works on alchemy, chemistry, and metallurgy-vide: the famous Biringuccio and he is a profound student (with a somewhat idealistic slant) of recent trends in world affairs and in what some incurable optimists call civilization; and at the same time he is still possessed of a sense of humor. Incidentally he is also one of the bestknown nonferrous metallurgists in this country and abroad, and for fifteen years has been a willing worker in A.I.M.E and the Institute of Metals Division.

Jan 1, 1943

By S. R. Rao

Interaction of potassium amyl xanthate with pyrrhotite has been studied thermochemically. Heats of adsorption of xanthate on unactivated mineral and the mineral activated with cupric ions have been compared with heats of reactions between potassium amyl xanthate and ferrous and cupric salts. It is shown that xanthate is consumed by stoichiometric exchange with anions present at the mineral surface. The floatability of the unactivated mineral is poor since xanthate is precipitated in bulk without creating a hydrophobic surface on the mineral. At the activated mineral surface, xanthate is adsorbed in certain isolated patches (active spots) and thereby creates a hydrophobic surface. The hydrophobicity of the mineral is greatly improved by lowering the pH to 4.5.

Jan 1, 1972

M. A. Hanna is investigating a nickel prospect near Riddle, Ore. Drilling is under way and a prospect shaft is being put down to obtain samples for metallurgical test work. The deposit is favorably situated for open pit mining. The property had been drilled previously by the USGS and by Freeport Sulphur Co. A $75,000 laboratory pilot plant will begin operations this year to determine if economic beneficiation of a deposit of low grade iron ore, being examined by M. A. Hanna in the Iron River, Mich., district, is possible. Three miles east of Randville 2560 acres of land have been acquired, and drilled, over the last 2 years. The ore is reported to be 34 pat Fe.

Jan 6, 1951

The largest variety of asphalt and related bitumen deposits in this country is found in Utah. Utah is one of the few places in the world where the hydrocarbon minerals, gilsonite or uintaite, wurtzilite (trade name elaterite) and ozokerite are produced. These bitumens occur in an area embracing nearly 10.000 square miles in eastern Utah near the Colorado line. This area is largely in the western part of the Uintah basin. The bitumens are in the Tertiary horizon in the various divisions of the Eocene series. Cilsonite is an asphaltite derived from petroleum, wurtzilite is an asphaltic pyrobitumen derived from petroleum, and ozokerite is a native mineral wax resulting from the metamorphosis of paraffinaceous petroleum.

Jan 1, 1925