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By A. B. Parsons

DOWN in Washington an army of individuals constituting the government of a so-called "'democratic" nation is trying to manage the conduct, in its rnultifold phases, of the greatest war in history for the country that is potentially, at least, the strongest in the world and on which, consequently, the major responsibility rests. The enterprise is one of unprecedented magnitude and complexity. That individuals and groups have made and are making serious blunders, both as to the establishment and execution of policy, is to be expected.

Jan 1, 1942

By Edward J. Felten

THE oxidation resistance of chromium and Fe-Cr alloys is increased by small additions of yttrium or other rare earth metals.1,2 In addition, the presence of the additives increases the resistance of these alloys to spalling of the external oxide above 1000°C. This ability to prevent spalling appears to be related to the formation of an internal oxide in alloys containing yttrium or the other rare earth metals. The internal oxide is found in the form of a filamentary growth concentrated in the grain boundaries of the unoxidized metal. In alloys containing yttrium this internal oxide was found to be either Y2O3 Or YCrO3.' In an earlier report,' the growth of the external oxide was found to be controlled by diffusion through the oxide layer. Thermal balance studies were used to establish the kinetics of external oxide formation. In this related study the rate of growth of the internal filamentary oxide has also been studied. The results obtained indicate that the growth of the internal oxide is also diffusion controlled. Internal oxidation appears to occur in at least two ways. Using copper alloys containing small amounts of silicon, Rhines 3 found that between 600" and 1000oC a subscale was formed which consisted of particles of silica dispersed in the metallic matrix. The conditions requisite to internal oxidation as suggested by Rhines are: 1) a solubility of oxygen in the alloy, 2) the ability of oxygen to diffuse at an appreciable rate into the alloy, 3) the possibility of the formation by the alloying element of an oxide more stable than the oxide of the host metal, and 4) a relatively low solubility of this oxide in the metal. These conditions are fulfilled for a number of other copper alloys.3-5 Furthermore, the relationship between the depth to which the internal oxide is formed and the oxidation time follows the simple parabolic law.6 The activation energy for copper containing small amounts of silicon, germanium, iron, or manganese as calculated from Rhines data6 is about 48 kcal per mole. In some cases the internal oxide is found segregated at the grain boundaries, especially near the the surface. Observations of this type of oxide formation have been reported by stead,7 Rhines,* and Lustman. Evans" cites these cases as examples of the simultaneous movement of anions and cations during oxidation. Furthermore, Evans states that the presence of a minor constituent with a high

Jan 1, 1962

By K. Takahashi, I. Iwasaki

it is well known1 that racemic mixtures of optical isomers can be separated by passing their solutions through a column packed with r- or 1-quartz powder so that one of the isomers becomes adsorbed selectively on the asymmetric quartz surfaces. Although the natural occurrence of r- and 1-quartz is more or less equally distributed, some localities show enough deviations toward a higher proportion of l-quartz2 to suggest that optical isomerism might influence quartz flotation. Beta-amines have an asymmetric carbon atom, and therefore optical activity may be expected. Beta-amines are reported to behave quite differently from alpha-amines in the flotation upgrading of certain oxidized iron ores.3 It is of interest, for both practical and theoretical reasons, to determine whether or not optical isomerism plays a role in the amine flotation of quartz. In this article the results of Hallimond tube flotation tests and of adsorption measurements using d-beta-phenylisopropylamine on both r- and 1-quartz are compared. D-beta-phenylisopropylamine was chosen for the tests because it is commercially available in optical isomers. MATERIALS AND METHODS Brazilian quartz crystals were hand-sorted according to the difference in trigonal trapezohedral faces, and each crystal was further checked by the Airy's spiral.4 The respective crystals were then crushed, and the -150 + 200-mesh fractions were screened out for the Hallimond tube tests. The samples were cleaned by brief leaching with warm, dilute hydrochloric acid, and then by repeated rinsing with distilled water. In preparation for the adsorption measurements, they were then dry-ground in a pebble mill for several hours, washed a few times with distilled water, and finally dried in a vacuum desiccator. By means of the Krypton gas adsorption method, the specific surfaces of r- and 1-quartz samples were determined to be 27,700 and 19,800 sq cm per gm respectively, the difference being due mainly to the decantation procedure rather than to the inherent difference in their grindability. D-beta-phenylisopropylamine was the only collector used in the study. It was solubilized by neutralizing with 110% of the stoichiometric requirement of 0.1 N hydrochloric acid. The specific rotation of the d-beta-phenylisopropylamine was determined with a polari-meter using sodium D line to be, Although the d-beta-phenylis~prop~lamine showed absorption maxima in the wave length region of 250 to 270 millimicrons, due presumably to the phenyl group, these peaks were too sensitive to be used for colorimetric determination of the residual concentration in the adsorption measurements. The amine-picrate method, used in the colorimetric analysis of dodecylammonium chloride,' was found to work satisfactorily for the d-beta-phenylisopropylamine. The adsorption densities were thus determined after equilibrating 40 gm of the ground quartz sample with 300 ml of solution by tumbling in separate glass-stoppered Erlenmeyer flasks for one hour. EXPERIMENTAL RESULTS Fig. 1 presents the adsorption densities of d-beta-phenylisopropylamine on the r- and 1-quarts in the pH range of 6 to 7.5. In agreement with data reported in the literature, the adsorption density of d-beta-phenylisopropylamine was slightly higher on the r-quartz than on the 1-quartz, although the difference was not as pronounced as one might expect from the capacity of r-quartz and 1-quartz to separate racemic

Jan 1, 1969

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metalliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land of which the surface is suitable for: agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar" method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years ago has become valuable agricultural land dotted here and there with growing towns. Frequent references will' be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are applicable to all coal-mining states. Briefly stated, the question is "Does the owner of the substrata or underlying mineral owe any duty of surface support to the owner of the superjacent strata or surface?" There is no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1928

By Thomas Fraser, H. F. Yancey

PRIOR to the war just ended, Germany was the greatest coal producer in continental Europe. In 1943 the production of coal, bituminous and higher in rank, together with brown coal calculated to the equivalent amount of bituminous coal, is estimated to have been about 240 million metric tons, according to the War Department. Before the war production in Germany exceeded consumption. No other country in continental Europe except Poland had a large surplus. However, England's surplus was the largest in Europe as a whole. Before World War II the Ruhr Basin normally supplied about 70 pct of the total production of high-rank coal, the Saar and Aachen about 6 pct each, Upper Silesia about 14 pct, and Silesia and Saxony the remainder. Nearly one third of the brown coal was produced in the Rhineland, a little less than one half in central Germany west of the Elbe River, and about one fourth east of the Elbe. Bituminous coal and brown coal together constituted by far the most important energy resources of the old German Reich. Bituminous coal furnished nearly 70 pct of the total energy requirement, brown coal supplied about 25 pct, and water power, wood, petroleum and alcohol together aggregated only 7 pct. Because it was the most important single mineral resource of Germany, an excess of coal enabled the Reich to import nearly all the other mineral products that she lacked, such as iron ore from Lorraine. The area adjacent to the coal fields was supplied with gas from an interconnected grid. Similar electric grids are based on brown coal with the power stations at the mines. Coal tar provided the foundation for the development of the extensive German chemical industries as exemplified by the I. G. Farbenindustrie. For almost a century, German scientists have been adequately supported both by the State and by industry in studying improved methods of utilizing coal. In Germany the mineral rights were reserved by the State and ordered extraction of coal was enforced. Each lease comprised a relatively extensive area, which accounts for the generally large size of the mines and mining companies. In 1938 there were 160 mines in the Ruhr, with a total output of 125 million tons but go pct of the production was controlled by 20 companies. By far the largest single coal-mining company in Germany was the Gelsenkirchener Bergwerke A. G., which produced nearly 27 million tons in the Ruhr in 1937. Second was Saargruben A. G., a State-owned company operating in the Saar, which produced more than 13 million tons. Third was Bergwerksgesellschaft Hibernia A. G., with 10 million tons, also in the Ruhr. Briquettes are made from both bituminous coal and brown coal, but in 1938

Jan 1, 1946

By AIME AIME

THOUGH Frank Wardlaw was born in the East- at Schroon Lake, N. Y., on July 14, 1887-and was educated in New York City-Columbia, E.M., 1916 he has spent his entire professional life in the West, and is still there, as assistant general manager of the Inspiration Consolidated Copper Co., in Arizona. His first jobs were as miner and surveyor for the Utah Consolidated Mining Co., at Bingham, where he worked under A. S. Winther, now general manager of Inspiration's adjoining big neighbor, the Miami Copper Co. After rising to the position of chief engineer and geologist, Mr. Ward- law left Utah Consolidated to go to Chile for two years with the Braden Copper Co. Then he returned to his

Jan 1, 1940

By R. S. Shoemaker, F. W. McQuiston

MAGMA COPPER COMPANY San Manuel Division The San Manuel Division of Magma Copper Company is located about 40 miles north of Tucson. Tons of ore milled in 1973 .were approximately 19 million at a rate of 63,000 tons per day. From this, about 42,600 tons of copper concentrate was produced as saying approximately 1.070 MoS2 and 28.5% Cu. As with many copper ores, the San Manuel ore contains a small amount of gold, but in this particular case, much of the gold follows the molybdenite. Separation of the molybdenite from the bulk sulfide concentrate by flotation produces a moly concentrate containing 9170 MoS2, just under 1.070 Cu, and 0.44 oz Au per ton. Cyanidation of this material for gold recovery is the only practice of its kind known to the authors of this Monograph. After thickening, the final moly concentrate is filtered for subsequent repulping with cyanide and lime. Gold dissolution takes place in three agitators in series with the pulp from the agitators being filtered in two stages in disc filters. Between filtration stages, the cake is repulped with barren solution. Filtrate from both filters is the pregnant solution. The Merrill-Crowe recovery unit is comprised of two solution tanks and the usual clarifying filter, vacuum tower, zinc dust feeder and Merrill precipitate press. Because of the presence of finely divided sooty chalcocite in the molybdenum concentrate, the cyanide consumption of 55 pounds per ton is extremely high. A compensating factor, however, is the low copper, moly concentrate produced. Precipitation of the gold from the highly copper-contaminated solution requires 0.56 pounds of zinc dust and 0.28 pounds of lead acetate per ton, high figures when compared to normal cyanidation practice. The Merrill- Crowe precipitate assays approximately 28.5% Cu, 8% Zn, 156 oz Au and 197 oz Ag per ton. The San Manuel cyanidation plant is an outstanding and innovative development.

Jan 1, 1975

By H. A. Wentworth

The Huff electrostatic plant of the United States Smelting CO., operated in conjunction with its wet concentrator at Midvale, Utah, was the second plant of substantial size installed using the Huff process, and the first plant to be put in operation on the so-called Western complex ores. , In spite of the machinery being of early design and consequently embracing many of the mechanical weaknesses incident to a pioneer plant the mill has operated steadily and uniformly since the summer of 1909, about five years now, without any material change other than some rearrangement of the machinery for better handling of the sizes. The ore, at present coming almost entirely from the company's mines in Bingham, is of practically the same composition as that upon which the plant was first put in operation. The crude ore, consisting of the sulphides of copper, lead, zinc, and iron, and containing small amounts of gold and silver, is brought by train and delivered to the hoppers of the wet concentrator, where by jig and table treatment, there are produced a shipping lead concentrate, a tailing, and a middling product, the latter being conveyed in push cars to the adjoining electrostatic mill. The crude ore delivered to the wet concentrator contains from 6 to 9.5 per cent. zinc. At times the plant is used also for the treatment of custom ores from the Bingham district and elsewhere, and at such times the results of the plant vary according to the material in use, but as by far the larger portion of the product is that from the company's own mines, the results given below are fairly indicative of the general work obtained. The diagram, Fig. 1, illustrates graphically the flow of the ore through the electrostatic mill. The middling coming from the wet mill, containing from 15 to 18 per cent. moisture, is hoisted while on the cars by an elevator, and delivered from the top of the elevator to a hopper over the drier. The drier first installed was of too low capacity to take care of the moisture present in the tonnage to which the mill was later

Jan 1, 1915

By C. A. Doh, R. Q. Fields, M. Lebourg

A formation tester run on logging cable is now available to the oil industry. It offers a method of safely and rapidly testing possible producing formations in uncased holes. These tests can be made up the hole after running the electric log. Reservoir pressure data is continuously recorded at the surface as the fluid sample is extracted. The tester may be assembled with a reservoir of 1-, 2.75-, or 5.5-gal capacity. A retaining pad on the body of the tool is expanded against the wall of the hole at the exact depth desired; this depth is determined by electrical log control. Two bullets are then fired through the center of the retaining pad which create a connection between the formation and a flow line to the sample chamber. When the chamber is filled, a valve is closed and the fluid sample sealed at maximum pressure. The tool is retracted to minimum diameter and brought out of the hole. Electrical circuits permit a complete recording at the surface of the mechanical operations of the tool as well as the formation pressure build-up and the hydrostatic mud pressure. The tool was introduced commercially during the latter part of 1955 in the Gulf Coasts of Louisiana and Texas. Over 1,000 operations have been made to date (Sept. 1, 1956); 50 per cent of which resulted in successful tests. Failures have been due mostly to ineffective sealing in unconsolidated sands. One major company had 41 successful tests out of 80 attempts with 23 ineffective pad seals. Results for this company were very gratifying as to pinpointing gas-oil ratios, indicating productive permeabilities and aiding in determination of fluid content where electrical log and side-wall coring information were inconclusive. Eight typical pressure curves are discussed (including misruns). Six types of fluid recoveries are interpreted. Eight actual field examples of electric logs, showing the problems solved by the formation tester, are illustrated. The present applications of the tool are discussed: 1. Determination of productive fluid—varticularlv differentiating between gas and oil. 2. Determination of reservoir pressure as an aid to: (a) safety in completion technique, (b) reduction in drilling costs, and (c) reservoir analysis. 3. Determination of minimum gas-oil ratios. 4. Location of gas-oil or oil-water contacts. 5. Recovery of samples for examination and analysis: oil (gravity); gas (hydrocarbon content); water (salinity). Additional applications envisioned for the future are also given: (I) subsurface exploration based on accurate pressure, (2) recovery of fluid samples from the undisturbed reservoir for PVT work, and (3) possible quantitative study of permeabilities or productivity index. Running the formation tester requires no special pre-cautionary measures. Because full hydrostatic mud pressure is maintained at all times, well depth is no problem. Thus, the method allows safe, economical testing in wells which heretofore could only be tested by setting casing. INTRODUCTION A new method of safely and rapidly testing possible producing formations in uncased holes is achieving considerable success. The method offers promise of further advances in reservoir study. Called the formation tester, the new instrument is unique in that it operates on logging cable. It thus offers all the advantages of wire-line operations and becomes an important adjunct to present logging and side-wall coring services. The tester is operated against the wall of the hole at any depth desired. Zones to be tested are usually determined by a study of the electrical and the micro-caliper surveys. Reservoir data, as well as the operating cycle of the tool in the hole, are continuously recorded at the surface during the operation. The tester, as it was originally designed, was capable of recovering a 1-gal sample of reservoir fluid per trip in the hole. Tools with reservoirs of 2.75- and 5.5-gal capacity are now available. The 5.5-gal reservoir is equipped with a segregating system, set before going in the hole, so that the last portion of the recovery (usually 1 gal) is automatically separated from the first portion. This makes it possible

Jan 1, 1958

Perhaps, after years of concerted effort at a mineral prospect, your company has reached the stage of feasibility study. Detailed target investigations, drilling, bulk sampling, land acquisition, and engineering analyses are complete, and the deposit still remains an attractive investment possibility. Your company, after long study, decides to begin mine development-now, how do you convince lending institutions that your proposed operation will return their borrowed funds, plus interest, over the term of the loan?

Jan 12, 1978

By D. Harrington

One of the main functions of the United States Bureau of Mines is to obtain and disseminate information that will promote safety in and around mines, and the health and safety of employees engaged in mining. Serious health and safety conditions arising out of contamination of air in metal mines by dust, fumes from explosives and fires, and absorption of oxygen by timber and other causes, led the Bureau of Mines to cooperate with the United States Public Health Service in the study of dust occurrence and ventilation in metal mines in various parts of the country. A. J. Lanza, of the U. S. Public Health Service, and Edwin Higgins, mining engineer of the U. S. Bureau of Mines, in 1915, made a detailed study in the mines around Joplin, Mo.; their reports1 are now available. In 1916, 1917, and 1918, a similar study was made in the Butte, Mont., region by Doctor Lanza and D. Harrington, mining engineer of the Bureau of Mines; the reports of this investigation will be available soon. In 1919, the study was continued in some of the Arizona mines by D. Harrington, of the Bureau of Mines, and G. E. McElroy and R. A. Koronski, of the U. S. Public Health Service, the underground work being completed in June, 1920; these reports are now being prepared for publication. In the spring of 1920, the scope of the work was extended, with D. Harrington in charge as supervising mining engineer, and short studies were made in the mines of the Coeur d' Alenes in Idaho and around Oatman, Ariz. It is hoped soon to extend the work into mines of California, Nevada, Colorado, Michigan, and Minnesota, and ultimately to other states should the mining companies be willing to coöperate. While the coöperation of the mining companies is necessary, the companies are put to practically no expense other than supplying a guide to accompany the investigators underground, the length of time spent

Jan 1, 1922

By H. W. Straley, G. R. MacCarthy, J. C. McCampbell, W. R. Johnson

In the spring of 1935 the authors undertook to compare the geomagnetic and direct-current carth-resistivity methods of tracing a concealed dike along its strike. An area near Chapel Hill, North Carolina, was selected, where a diabase dike was known. For rapid reconnaissance the magnetic method offers several advantages ovcr the electrical. The resistivity method is useful in determining the position of underground water, a factor of consideration in regions where mining is contemplated. All factors considered, the coincidence between the positions of the dike as determined by the two methods is striking.

Jan 1, 1940

By W. R. Johnson, H. W. Straley, J. C. McCampbell, G. R. MacCarthy

In the spring of 1935 the authors undertook to compare the geomagnetic and direct-current carth-resistivity methods of tracing a concealed dike along its strike. An area near Chapel Hill, North Carolina, was selected, where a diabase dike was known. For rapid reconnaissance the magnetic method offers several advantages ovcr the electrical. The resistivity method is useful in determining the position of underground water, a factor of consideration in regions where mining is contemplated. All factors considered, the coincidence between the positions of the dike as determined by the two methods is striking.

Jan 1, 1940

By M. D. Cooper

UNDERGRADUATES in mining engineering may be prepared for work by giving them sound instruction in the courses generally considered essential to the profession. The industry is not deeply concerned about the details of those courses. The average man in the coal industry does not wish to insist upon a rigid program. Therefore, he differs little from those in the teaching profession-who evidently are not unanimous in their opinions, or all college catalogs would be alike. For the good of the profession, it is just as well that there should be differences in regard to details. It appears that students graduating in mining engineering from the accredited institutions receive similar instruction.

Jan 1, 1950

By B. M. Larsen, J. W. Campbell

Several articles have recently been published discussing the conditions necessary for accurate measurements of temperatures in the open-hearth steel furnace. In the course of a study of refractories service conditions in steel furnaces, the present writers have taken temperatures in several open-hearth shops in the Pittsburgh district. The conclusions, as to conditions necessary for accurate measurements of temperature, are somewhat at variance with those of other investigators. The subject is closely connected both with the close control of steel-making and the prevention of overheating of the silica refractories used in roofs and walls. It is becoming more and more important to obtain furnace temperatures of fairly definitely known accuracy. At present, the most useful instrument for such measurements is the disappearing-filament type of optical pyrometer. This method of measurement has formed the basis of most other discussions on the subject and was also used by the writers. Previous Investigations In 1916, Burgess' made perhaps the first systematic series of measurements in steel furnaces. The emissivity figures of 0.40 for liquid steel and of 0.53 to 0.65 for liquid slags had been determined by the Bureau of Standards and were used by Burgess in this work. These correction factors are still being used and are regarded as fairly accurate, so that the tapping and teeming temperatures on metal streams given by Burgess should be very nearly correct. Most of his temperatures of furnace roofs and slag surfaces were taken while flames were present in the furnaces and include a few roof temperatures above 1700' C. (3100' F.).

Jan 1, 1927

By G. Van Esbroeck, M. Van Weyenbergh

The copper mines of the Katanga region in the Belgian Congo lie along the same mineralized belt as those of Northern Rhodesia. There are two distinct types of deposits in that belt, the dolomitic and the quartzitic. In the dolomitic type the metallic minerals are found in a dolomitic limestone country rock. Through oxidation and enrichment, large deposits of high-grade oxidized copper ores were formed, some of which are being worked by the Union Minière du Haut Katanga. Such deposits are all in Katanga. The quartzitic deposits are found in Katanga and Northern Rhodesia. Here the primary mineralization occurred in sandstones and quartzites, in horizons stratigraphically lower than the dolomites. These rocks are not favorable to secondary enrichment and the oxidized zone is poorer than the sulphide zone, which alone contains the ore. There are also in Katanga a few ore-bearing veins. One of them is being worked in the Prince Leopold mine at Kipushi. Prince Leopold Mine The Kipushi ore body fills a fault vein and invades the wall rocks more or less extensively by metasomatic replacement. The vein strikes north-northeast and south-southwest and dips to the west. The variable dip averages 60' to a depth of 300 ft., and more uniformly 80' below 400 ft. In the upper section the average width is 200 ft. and below the width is about 150 ft. The length of the ore body is 2300 feet. The eastern side of the vein—the footwall—is dolomitic and contains irregular masses of ore sometimes extending 100 ft. or more from the main

Jan 1, 1940

By M. Van Weyenbergh, G. Van Esbroeck

The copper mines of the Katanga region in the Belgian Congo lie along the same mineralized belt as those of Northern Rhodesia. There are two distinct types of deposits in that belt, the dolomitic and the quartzitic. In the dolomitic type the metallic minerals are found in a dolomitic limestone country rock. Through oxidation and enrichment, large deposits of high-grade oxidized copper ores were formed, some of which are being worked by the Union Minière du Haut Katanga. Such deposits are all in Katanga. The quartzitic deposits are found in Katanga and Northern Rhodesia. Here the primary mineralization occurred in sandstones and quartzites, in horizons stratigraphically lower than the dolomites. These rocks are not favorable to secondary enrichment and the oxidized zone is poorer than the sulphide zone, which alone contains the ore. There are also in Katanga a few ore-bearing veins. One of them is being worked in the Prince Leopold mine at Kipushi. Prince Leopold Mine The Kipushi ore body fills a fault vein and invades the wall rocks more or less extensively by metasomatic replacement. The vein strikes north-northeast and south-southwest and dips to the west. The variable dip averages 60' to a depth of 300 ft., and more uniformly 80' below 400 ft. In the upper section the average width is 200 ft. and below the width is about 150 ft. The length of the ore body is 2300 feet. The eastern side of the vein—the footwall—is dolomitic and contains irregular masses of ore sometimes extending 100 ft. or more from the main

Jan 1, 1940

By Chester A. Fulton

APATITE, the most abundant crystalline phosphate mineral, is found in igneous rocks and probably is the primary origin of all other phosphates, whether mineral or organic. Its chemical formula may be expressed as Ca5(Cl,F) (PO4) 3. The chlorine may be replaced almost entirely by the fluorine. It is found in large or small hexagonal prisms, usually of a vitreous luster and a green or red color, but also violet, white, or yellow. It is found largely as an accessory mineral in granitoid rocks. Its hardness is 4.5 to 5 and its specific gravity is about 3.2. There are many other phosphate minerals-for instance, amblygonite, autonite, collophane, lazulite, monazite, pyromorphite, torbenite, triphylite, turquoise, vivanite, wavellite-with base elements of calcium, magnesium, iron, aluminum, manganese, lead, cerium, lanthanum, lithium, or several of these in combination and with various amounts of water of crystallization. However, these phosphate minerals have but little value save as specimens for mineral collections, the exception perhaps being turquoise. While large deposits of igneous apatite are mined today for the production of fertilizers and chemicals, more than 90 pct of the world phosphate production is derived from secondary apatites, called phosphorites. These calcium (and magnesium, aluminum, and iron) phosphates have been formed in the alteration of sediments by solutions containing phosphoric acid. Such solutions have come from the weathering or leaching of igneous rocks containing apatite, bone deposits of prehistoric animals and marine life, or guano deposits (excreta of birds). These phosphorites are mostly alterations of phosphatic limestones that took place slowly over many years. Whether it is apatite or phosphorite that is being produced, it is known in the trade as "phosphate rock." The sedimentary phosphate deposits are of marine origin. Some, as laid down, were rich in phosphate or have become so by subsequent subaqueous action and have not been further enriched since emergence from the sea. Some were originally phosphatic limestones or marls from which calcium carbonate was dissolved away by waters containing carbon dioxide, in which calcium carbonate is much more soluble than

Jan 1, 1949

By Vince Poxleitner, John Delaney

Introduction In the mining industry, comminution typically begins in the mine with a blast of explosive to break rock so that it can be handled by the avail- able equipment. Though the breaking of the rock is essential for material handling in the mine and plant, this is not the only reason for ore reduction in the mineral industry. Comminution is primarily required to liberate minerals from ore so that they can be concentrated into valuable products or to prepare minerals, such as talc, for market as mined. The size of the equipment used for comminution ranges from small to massive. Regardless of equipment size, the power required to reduce the rock is a major expense. Years ago, mineral deposits could be mined more selectively and required less grinding to produce saleable products. However, as richer deposits were depleted, it has become necessary to mine low-grade deposits, with the valuables dispersed throughout the rock. Comminution equipment evolved in physical size and capacities to meet the new mine and process requirements. A modern, modestly sized mining operation, with a capacity of 25.000 TPD may use crushers two stories high weighing over a million pounds, SAG mills 36 feet in diameter driven by dual motors putting out 10.000 horse- power, and ball mills over 16 feet in diameter . Because of the increasing size and weight of modern equipment, the builder is faced with the problems of erecting massive foundations and field assembling equipment on these foundations. As equipment costs and plant construction costs increase, builders are finding that owners are asking for more detailed progress and cost data. Comminution construction projects are generally classified as grass roots plants or expansions or modifications to existing plants. It is estimated that 60-702 of the jobs involve existing plants. Today ' s costs for construction of small, new comminution plants can reach tens of millions of dollars; larger plants can cost hundreds of millions of dollars. Modifications, on the other hand, usually run from a few thousand to several million dollars. Though many problems are common to the construction of both new plants

Jan 1, 1982

By Francis A. Thomson

IN reviewing mineral industry education a year ago, occasion was taken to congratulate the Institute in general and to felicitate the Education Di- vision in particular on "the most gratifying growth which is taking place in Institute consciousness in regard to its responsibility for the recruitment and adequate training of student personnel and for the successful bridging of the difficult gap between graduation and achievement of professional status." Continuation of this growth of interest throughout 1939 is a recognition of the validity of the splendid statement of George Otis Smith that the mining students of today are the ore reserve of the Institute for the future. In this connection one recalls the equally apt expression of another distinguished geologist, George M. Fowler, who, speaking of exploration for ore deposits, says, "The place to look for elephants is where elephants have been found."

Jan 1, 1940