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By J. R. Thoenen, M. C. Malamphy, G. K. Dale

The beginning of the war and the events leading up to it precipitated a near crisis in the aluminum industry. Demands for the metal reached proportions far beyond the prewar production capacities and, in addition, the submarine menace seriously curtailed the importation of bauxite from South America, hitherto a chief source of high-grade ore. The situation required an intensive search for domestic ore to augment the reserves and in October 1941 Congress directed the Department of the Interior to investigate the extent, mode of occurrence, and quality of bauxite in the United States. In December of that year the Bureau of Mines and the Geological Survey began the search for bauxite in Arkansas, where more than go per cent of the domestic ore had been produced and where the greatest amount of bauxite was known to occur. The program involves the geophysical and geological investigation of the Arkansas bauxite region and the core drilling of areas considered favorable for the occurrence of bauxite deposits. Cores taken from the bauxite-kaolin zone are sampled and analyzed in the Bureau of Mines laboratory in Little Rock. The information from each of the deposits discovered is then assembled, the bauxite is graded with respect to its possible utility, tonnage estimates are made, and the whole is presented in the form of a war minerals report. Thirty-eight new bauxite deposits had been discovered and investigated at the end of the calendar year 1944, and the presence of several others had been indicated by the drilling. More than 5000 holes had been drilled throughout the bauxite region, and more than 60,000 chemical analyses had been made of samples taken from the bauxite-kaolin zone. A study of the chemical analyses led to certain general conclusions not only with regard to the chemical composition of Arkansas bauxite, but also with regard to its component minerals. Charts and diagrams based on these conclusions have been developed for practical use by the Bureau of Mines: (I) to serve as a check against laboratory analyses, (2) to present tonnage estimates of ore bodies based on mineral composition, (3) to illustrate the relationship of tonnages of bauxite to the alumina, silica, and iron content, and (4) to serve as a control for mining operations by providing a means for quick estimates of the value of the ore from a partial analysis of its chemical constituents. The use of charts and diagrams similar to those discussed in this paper-- is not new. The use of the trilinear diagram for studying the ultimate analyses of coals as of proposed by Ralston in Bureau of Mines Technical Paper 93 (1915) showed that the various ranks of coal fell in different areas on the diagram and that volatile matter, calorific value and other properties could also be plotted by the use of contours. A considerable subsequent literature, largely on classification of coals, has accurnulated since then, showing the utility

Jan 1, 1948

By E. W. Newman

During 1943 and 1944, there was an urgent need for certain grades of optical calcite (Iceland spar) for instruments for ' military uses. To find a supply of this material, prospecting was carried out in Montana, California and Colorado. Although some production was obtained by the work in California, the best results were from prospecting the large calcite veins of south central Montana. The bulk of the optical calcite mind during World War II has come from that area. The Bureau of Mines took an active part in the search for optical calcite in Montana. It examined most of the known calcite veins in the 70-mile distance between Wilsall, on the Shields River: and Absarokee, on the Still water River, and conducted exploration on several of the deposits. The Geological Survey also took an active part by mapping many of the veins. Actual mining of the calcite was performed at first by Calcite Operators, Inc., and later by the Metals Reserve Co., through an agent. A sorting plant was established at Clyde Park, where custom material could be sold. These activities stimulated mining by private operators. To be suitable for military uses, the calcite mined had to meet rigid specificstions as to both size and quality. Individual crystals had to be clear and transparent and if in the form of rhombs had to measure at least 7/8 in. on each edge. Some color and a few inclusions in the calcite were allowable, but material with incipient or developed cleavages, or showing twinning other than parallel to the base, was unacceptable. History of Deposits The existence of large veins of calcite in south central Montana has long been known, and for many years the farmers of this region have used the common vein calcite for producing grit for chicken feed. According to reports, the fist optical calcite produced from Montana came from the Cartwright deposit near Grey-cliff,' but until recently the mining of optical calcite in Montana has been limited to spasmodic searching for small crystals suitable for making nicol prisms for saccharimeters and microscopes, or for mineral specimens. The possible need of substantial amounts of optical calcite for military uses began to appear late in 1942 and early in 1943, therefore the Polaroid company began searching for a source of supply in Montana and California. Work on the Wade property near Clyde Park was started on a small scale in the fall of 1942, by .4. H. Hansen, of Clyde Park. During the winter and spring of 1943, a modest quantity of optical calcite was mined and shipped to the Polaroid Corporation, Cambridge, Mass. Most of this was produced from the "Hansen vug," which was found close to the surface. Early in the summer of 1943, mining on the Wade property was undertaken by Calcite Operators, Inc., a company organized for mining optical calcite from the

Jan 1, 1948

By George E. Moore, B. K. Miller

The Missouri fire clays are here divided into plastic and semiplastic clays occurring as widespread bedded deposits in east central Missouri and flint and diaspore clays occurring as isolated "sink-hole" deposits in the north central Ozark region. Visual inspection was the first method used in clay prospecting. Thin overburden, hard sandstone "rimrocks," and the occurrence of diaspore float made this method particularly applicable in the flint and diaspore fields. The first drilling tool used was a hand auger. One man can drill 25 to 50 ft. per day at a cost of about 35 cents per foot. Holes can be drilled to a depth of 150 feet. Spud drills are often used where the overburden is hard. This drill uses a slotted earth socket bit. A two-man crew can drill about 100 ft. per day at a cost of about 35 cents per foot. Mechanically powered auger drills have been used extensively in wildcat drilling in the past few years. This type of drill furnishes a continuous set of cuttings. The practical depth limit with this drill is 50 to 60 ft. Two men can drill 300 ft. per day at a cost of about 20 cents per foot. Core drilling is used mainly to prove a known 'lay deposit. A A crew with a No. 22 Sullivan drill can drill about 30 to 40 ft. per day in soft clay, at a cost of about $1.25 per foot. Introduction Because of the geological variations in the Occurrence of the several types of fire clay mined in Missouri, it is necessary, when discussing the prospecting methods used for discovering and proving these clays, to divide these operations into two classes, one including plastic and semi-plastic fire clays, the other flint and diaspore clays. The plastic and semiplastic fire clays in the east central and St. Louis districts are generally classified as Cheltenham clays. This formation is a more or less continuous deposit and is found Over a large area in east central Missouri. There are variations, however, in the quality and thickness of the clay, which necessitate detailed prospecting in order to determine deposits of economic value. The nature of the overburden (Fig. 1), which consists of Pennsylvanian limestone and shale beds of varying thicknesses, and a mantle of glacial drift, regu1ates the methods and equipment used in prospecting for these clays. The district in which these clays occur is a gently rolling upland region, characteristic of most of northern Missouri. Along the southern fringe of this area there are numerous deposits of flint clay lying as masses or lenses in depressions at the base of the continuous and widespread Cheltenham formation, or as outlying "sink-hole" deposits in the area marginal to that formation. South of the Missouri River in the north central Ozark region, there are high-grade flint and high-alumina clays, commonly referred to as burley and diaspore clays in sink-hole type deposits. The overburden On these deposits is thin, consisting chiefly of soil and hard-pan, which varies from a plastic

Jan 1, 1948

By S. H. Lorain, Norman L. Wimmler, S. Ricker, P. E. Oscarson, H. G. Iverson

This paper has been prepared with the principal objective of recording the results of the Bureau of Mines exploration of five major clay deposits in the Western Region. It is based mainly on data contained in unpublished Bureau of Mines reports. Acknowledgment is made to the Federal Geological Survey for its cooperative work with the Bureau of Mines, to the various State geological and mining departments, and other State and local agencies. Clay Exploration by the Bureau of Mines Much has been written and published on clays and clay deposits relating to their refractory, ceramic, and other qualities but such literature is lacking in analyses of the available alumina content of the clays and provides little indication of their possibilities as a source of alumina. With this new objective in view, a great many of the known clay deposits were reexamined and new ones discovered. The Bureau of Mines made preliminary examination of numerous areas in the western United States. Five of those most favorably indicated were systematically drilled, and in each a large amount of high-alumina clay has been found. These five major projects are Molalla and Hobart Butte, in western Oregon; Cowlitz-Castle Rock, in southwestern Washington; Ione, in California; and the Olson-Troy area in Idaho (Fig. I). Preliminary scout drilling was done in the Stockton deposit at Coeur d'Alene, Idaho; the White ware deposit near Lewis-town, Mont.; and 13 areas in the Spokane or eastern Washington region, where the most favorably indicated area, known as the Excelsior, is now being drilled more systematically. Preliminary drilling was undertaken in numerous areas adjacent to the major deposits and others more remote. As a result, large additional clay possibilities were found. The Clay Deposits The clay deposits under consideration are of the sedimentary or transported types, parts of which have been altered further by the agencies of weathering, ground water, or hydrothermal action. There are extensive deposits of residual clays in northern Idaho and in eastern Washington, but they have been found to be low in the available alumina and to contain much free quartz, mica, and unaltered feldspar. To be of value, they must first be subjected to beneficiation to remove these gangue minerals. The sedimentary clays have been derived largely from the decomposition, erosion, and transportation of granites, gneisses, schists, and basalts. At Molalla, some

Jan 1, 1948

By Leon W. Dupuy

A brief elemental discussion of the fundamental factors involved in diamond drilling often fills a need, particularly when a mine operator is contemplating for the first time an exploratory drilling campaign. Mr. James A. Barr, of the Mining Methods Committee of the Institute, has suggested that many engineers must undertake a drilling program of one kid or another and, in the case of diamond drilling, sometimes even are at a loss as to how to start correspondence. The Bureau of Mines has acquired much experience in managing exploratory diamond-drilling activities. Its activities in diamond drilling included exploring for potash in Texas, Utah and New Mexico1-' during the 1920's. The Strategic Minerals Exploration program was started in 1939 and was materially expanded during the war to include critical and essential minerals. At the peak of its war-time activity more than 200 engineers were employed, a majority of whom supervised diamond drilling. Many of them had little experience with such work prior to their employment with the Bureau, and it was necessary to instruct them in their duties. The purpose of this paper, therefore, is to present the fundamentals of exploratory diamond drilling from the viewpoint of management in such a way that they will Serve as a basis on which those beginning exploratory diamond drilling may build an experience and acquire ability to direct exploration as they gain that experience. Selection of Method of Drilling Selection of the method of drilling is governed by the type of material to be penetrated and by the type of sample needed to determine the quality and importance of a deposit. Types of drills that might be used for a given job include diamond drills, churn drills, hand auger drills, power auger drills, bucket drills, and rotary drills (sometimes called "seismograph rigs"). Each type has a specific field in which it is most useful. While the Bureau of Mines utilized all the types of drilling mentioned, diamond drilling was used on a majority of its exploratory projects. Factors Governing Selection of Diamond Drilling The prime consideration in selecting a method of drilling is first to determine what results are desired and then to choose a method that will furnish reliable data in the ground to be penetrated. Use of diamond drills permits recovery of a core as well as sludge at a comparatively low cost. The core provides an excellent means of studying the formation being drilled and furnishes much information that would be difficult to obtain otherwise. Diamond drills will recover a satis-

Jan 1, 1948

By Frederick L. Knouse

The south border of Espirito Santo begins about 400 km. north of Rio de Janeiro and extends along the Atlantic Coast northward some 325 km. and inland 100 to 150 km. The area under consideration, where quartz crystal of strategic grades has been mined, extends from 19º to 21º and 30º south latitude; and from 40º to 41º and 30º west longitude. This includes the central part of Espirito santo, chiefly south of the Rio Doce from the Atlantic ocean, and west across the border into Minas Gerais near the town of Aimores, in the municipalities of Aimores, Minas Gerais; Baixo Guandu, Santa Teresa, Santa Leopoldina, Colatina, Joao Neiva, Fundao and Domingo Mar-tines, Espirito Santo (Fig. I). During 1943 and the first half of 1944, this region accounted for approximately 3 to 5 per cent of the quartz crystal produced in Brazil. Shipments of crystal have been made chiefly by rail to Rio de Janeiro. This region is serviced by the E. F. Minas-Vitoria and E. F. Leopoldina to Rio de Janeiro through vitoria; and by the E. F. Minas-Vitoria and E. F. Centra] do Brasil through Bello Horizonte, Minas Gerais to Rio de Janeiro. The major deposits are accessible from the railheads by dirt roads, some being 5 to 30 km. off the road, reached by trail. In 1943 and the first half of 1944, the bulk of the production was from inter- mountain marshes and adjoining hillside alluvial placer deposits in the zone surrounding the town of Santa Teresa. Most of these deposits were formed from the erosion of pegmatite~, quartz veins and pockets in the gneiss, with minor quantities produced from miarolitic cavity fillings in the granitic rock. Early Operations Mining of quartz crystal in this region began in 1928 and has been stimulated by the market demand for military uses. Before 1936 little attention was given to it, either in Espirito Santo or eastern Minas Gerais. From 1936 to 1941 the Japanese sent agents to various points of production or potential production to acquire quartz through purchase. They bought crysta1 as small as 10 grams. Since '94' only the United States and Great Britain have received quartz from Brazil. The United States purchases crystals of 100 grams and larger for strategic purposes. The first known discoveries were made either in the municipalities of Aimores, Minas Gerais, or in Baixo Guandu, 01 Domingos Martines, Espirito Santo. Marketable quartz crysta1 was first found either in the massive quartz replacement veins of the Victor Hugo mine in the municipality of Domingo Martines, or in the large 'ores of quartz in the pegmatites near Baixo Guandu, extending into Minas Gerais. Production The production of quartz in Espirito Santo from 1936 through 1941 as recorded

Jan 1, 1948

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By James A. Barr

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By I. M. LeBaron

The phosphate ore, or matrix, is a mixture of white pebbles of phosphate, of all sizes but mostly minus I to 1 1/4-in. diameter, in a matrix that varies from nearly all silica-sand gangue to a mixture of pebble, sand and clay. There is an occasional streak of hard pan of sand cemented with iron oxide, which can be drilled without much difficulty.

Jan 1, 1948

By W. F. Guenther

The usual hand-operated drilling outfit consists of a 4-in. post-hole auger with 3/4,-in. pipe for drill stem, in 4-ft lengths, with a turning handle fitted to a top pipe T. The auxiliary tools are: a chisel-bit drill made from 3/4 or 7/8-in. tool steel welded to a 4-ft length of 3/4-in, pipe, so that the regular pipe string can be used; also a churn or "mule foot" made from 3-in. pipe, slotted on one side, belled to a 4-in. tempered cutting edge on the bottom, all welded to a 3/4-in. coupling by a yoke. Other tools required are pipe wrenches and cleanout tools made from old auto springs (Fig I). A 4 1/2 or 5-in. collar welded to a plate is often used to protect the mouth of the drill hole. In general the auger is used in the typical clay overburden and brown phosphate matrix, which is relatively soft. The churn or "mule foot1' is used in hard pan, lump phosphate or cherty ground. The drill is used for breaking flint, often found loose in the overburden. The drill with the chisel bit is used for trimming sides of the hole, sounding for lime bottom and breaking through hard lumps. Holes have been drilled to a depth of 80 ft, but the limit of efficient operation is about 50 ft. In deep holes it is necessary to unscrew the string in 20-ft lengths, to

Jan 1, 1948

By H. O. Pickard

The Hoover and Mason Phosphate Co. made extensive tests with a rig manufactured by the Paris Manufacturing CO. as shown in Fig I. It is powered by a 20-hp Wisconsin air-cooled gasoline engine, through a single reduction gear and flexible coupling. The machine operates a 4-in. auger with a detachable cutting head, as shown in Fig I. The auger length is 3 ft 4 in. and the cutting head averages 7 in. The unit has a drilling capacity of 100 ft and can drill an average prospect hole in less than 15 min. The weight of the motor is used for the thrust feed for driving the auger and head down, aided by the spiral shape of the auger. The rate of downward motion—i.e., the feed—is regulated by a handwheel. The string of tools is withdrawn from the hole by a gear train controlled by a hand-operated clutch. In fairly dry strata, not of the consistency of mud, the action of the auger

Jan 1, 1948

By Hendon R. Johnston

In the Tennessee Valley Authority's program of investigation and treatment of foundations for major structures, many chert, or flint, bodies have been encountered during the diamond-drilling operations. These chert bodies occur most frequently in the Knox dolomite and

Jan 1, 1948

By G. C. Weaver, G. T. Harley

Beds or lenses of potash and magnesium salts are found in a thick salt section (Salado) overlain by Rustler Red Beds in several members of which water is present and from one of which the rehery process water used by International is obtained. Most of the holes drilled are less than 1000 ft. deep, but some wildcat holes have exceeded 3- ft. cable or rotary tools are used to drill down to the salt. when samples of water are desired the cable rig is used, but when this is not necessary, and where caving material is present, the rotary rig has an advantage. The rotary rig has a further advantage in that only one machine is required to drill and core the entire hole, whereas the cable rig must be moved off to make way for the core drill. Casing is placed in the upper section of the hole as required to shut off water, and a 5 3/16 in. string is set in the top of the salt before coring starts. With the rotary rig drilling is often carried to the salt with no casing, as drilling mud seals off caving ground and water-bearing strata, and a string of 4-in. line pipe or 4-in. flush-joint casing is landed on top of salt. Several types of gasoline-powered core rigs have been used in the field and all recover a 2 1/2-in. core. More recently the Sullivan Model 37 rotary rig has been tried, and a Sullivan Model N has been adapted to use a rotary bit in the upper section. Core is recovered in 20 ft. sections with a double-tube core barrel, and the bit used is a bottom-discharge type set with diamonds. The drilling fluid must be a saturated brine to prevent solution and etching of the minerals present. Blowouts are apt to Occur from nitrogen gas trapped under the several polybalite beds, and some have been strong enough to blow the tools out of the hole. Core recovery is practically loo per cent. All holes are plugged after drilling, with cement through the salt section and opposite each water horizon* and mud through the remainder of the hole. Cores are carefully logged and preserved, and in sections containing potash and magnesium minerals they are quartered and analyzed. The correlation of Ore beds between drill holes is briefly described. Introduction Beds Or lenses of potash and magnesium salts are found at varying depths in a thick deposit of salt (Salado formation) in what is known as the Permian Basin, in southeast New Mexico and West Texas. The Salado formation is Composed chiefly of common salt (halite) with numerous beds of anhydrite, polyhalite, and the soluble potash minerals carnallite, sylvite and langbeinite. Many other minerals are present in small amounts but their Presence has no bearing On the coring technique. Before starting to core the salt section it is necessary to penetrate 300 to 600 ft. of unconformably overlying Permian sediments (Rustler formation) which are composed of red and gray clay, sand, anhydrite, dolomitic limestone and occasional lenses of salt. The upper part of the formation is predominantly anhydrite, and the lower part predominantly clastic. A thin bed of dolomitic limestone, known

Jan 1, 1948

By Frank H. Macpherson

When it became apparent early in 1941 that the United States might be drawn into the war, studies were made of the bauxite situation in Arkansas, principally because 9.5 pct of the known bauxite reserves of the country were located in that State. Bauxite mining was then geared for maximum production to supply ore to meet this country's war requirements and, if necessary, to supply the needs of Canada as well. In view of the comparatively small bauxite reserves, Congress appropriated funds for an extensive exploratory drilling program to be carried out by the Bureau of Mines in cooperation with the Geological Survey. An alumina plant was erected near Bauxite and an aluminum plant near Hot Springs, Ark., by the Defence Plant Corp. The Metals Reserve Co. established a schedule of prices, arranged for stockpile sites and a buying agency. Operators cooperated to step up production and new ones came into the field. Production Record Prior to 1941, the greatest annual production in Arkansas was 562,892 long tons, dry basis in 1918. During the single month of August 1943, 693,596 long tons were mined—130,704 tons more than for the entire year of 1918. In general the Arkansas bauxite deposits are relatively small, irregular in thickness, somewhat scattered and, compared to coal, iron or open-pit copper deposits, are ill-adapted to an expansion in output. Commercial deposits range in horizontal extent from less than an acre to about 40 acres and are usually very irregular in outline. The average thickness of all known workable deposits is between 12 and 15 ft. with a maximum of about 60 ft. The ore bodies are usually somewhat undulating and nearly horizontal although locally some deposits dip as much as IS°. Types of Bauxite Three physical types of bauxite may be recognized: pisolitic, granitic and amorphous. Pisolitic ore is the most common type. It consists of small pebble-like nodules, ranging from the size of a pin head up to several inches in diameter, all set in a fine grained matrix. Transported bauxite is usually- pisolitic. Most residual bauxite is granitic. It is believed not to have moved appreciably from the location where it originally was formed. This is indicated by the fact that it appears to grade into unaltered nephelite syenite, which it overlies. Amorphous ore is the least abundant. It is nonpisolitic and resembles clay, has no characteristic texture, and can be identified definitely only by chemical analysis. Uses of Bauxite Bauxite is chiefly used for, and at the present time is substantially the only

Jan 1, 1948

By George A. Morrison

A deposit Of limestone Was known to exist at a depth of 2000 ft under the property of the Columbia Chemical Division of the Pittsburgh Plate Glass Co. at Barber-ton, Ohio. A 662-acre site was selected for the projected mine, some two miles northwest of the plant and near the main line of the Erie Railway. An electric railway 8800 ft in length connects the mine and the plant. The deposit is overlain by 18 ft of un-consolidated (sand and gravel), 100 ft of water-bearing sandstone, and finally 2080 ft of shale into which thin layers of sandstone are embedded. The limestone bed itself is 345 ft thick and overlies 200 ft of gypsum. A 300-ton-per-hour capacity mine was decided upon. Two shafts were deemed advisable, one for production and the second for service; and these were sunk 550 ft apart, one to a depth of 2323 ft and the other to 2258 ft. Each is 16 X , ft in the clear and timbered with 6-in. steel H-sets on 8-ft centers, using 3/8 X 4 X 4-in. angles as studdles. Twelve inch I-beams were used at 160 ft intervals as bearers set in deep hitches and concreted to a vertical depth of 8 ft. Wooden sheathing was first employed but sloughing of the shale created a pressure on this lining and finally concrete was deemed necessary. Water was encountered only within the first 315 ft, flowing at 60 gpm and by grouting this was reduced to 15 gpm. Temporary wooden sinking headframes were installed with 300 cu ft capacity storage pockets and with doors automatically controlled by air cylinders by hoistmen. Each shaft was operated on four 6-hr shifts. The usual V-cut was drilled at the center of the shaft and the round consisted of 34 holes- A 40 pet gelatin dynamite was employed with some 60 pet in the cut holes. Drilling crews consisted of four to six men. Shale drilled easily but became more bed in depth and sandstone wore away the gauge Of the bits rapidly. A room-and-pillar mining system was adopted whereby rooms turned off on 80-ft centers, each room 40-ft wide and 50-ft high. Rib pillars between rooms were cut into 100 ft lengths by frequent holes. Ventilation is achieved through the two shafts, the down-draft through the service shaft, and the return through the pr0duction shaft. The hoist has a a Of 300 tons per hour and is equipped with 10-ton balanced skips requiring. a 2-min cycle Or 30 trips Per hour- Hoisting is designed to Operate by automatic loading and no hoistman is required for normal Operation. The 48 X 60 in. jaw primary crusher is underground. It is fed through chute and chain feeders and is flood-oil lubricated and cooled. An inclined belt conveyor returns oversized material to the crusher. Tramming is by Diesel-powered trucks.

Jan 1, 1948

By W. J. Millard

It is well known that the excellent mica from Brazil played a most vital role in World War 11. Increased production from Brazil was necessary and with the assent of the Brazilian Government engineers from the united' States went down to study the problem. One of the means advocated by a former Chief of Metals and Minerals Branch of the Board of Economic Warfare, Mr. Carl Schwegler, was the use of stripping machinery. On a pegmatite dike favorable for stripping, a small number of miners could produce as much mica per day as an underground mine employing many times the same number of men. Type of Deposit Favorable The most favorable type of pegmatite for stripping is that which lies more or less parallel to the surface of the slope of a hill. Pegmatite dikes that cut directly into a hill are not suitable for stripping except where a long outcrop extends along the slope. Then just the outcrop could be stripped to some advantage. The ratio at no time should be greater than 1: 3; i.e., I cu. m. of pegmatite to 3 cu. m. of waste, unless the pegmatite was extremely rich throughout the dike. The Economics of Stripping When a mineral is badly needed to win a war, not too much heed can be paid to costs. The object is to produce rapidly and in quantity. Again, a deposit containing a superior grade of mica may be worked although the pegmatite is more costly to work than another deposit containing a considerably greater amount of poor-grade mica. For example: one deposit may have a little mica that will run 11 per cent good stain and better when trimmed and contain 2 kg, of crude mica per cubic meter of pegmatite, while another may run 0.2 per cent of good stain and better, and have a mica content of 10 kg. per cubic meter. A number of stripping projects were found in the vicinity of Raul Soares, Minas Gerais. These were sampled in the various old workings by cutting out a cubic meter of pegmatite and saving the usable mica. Because of the proximity to the surface of most stripping projects, about 34 per cent only of the mica is good for trimming. The other 66 per cent is too badly weathered to be of use. In Table I are given data collected on five properties near Raul Soares. In Table I, "value per cubic meter of pegmatite" means the value of the qualified mica obtainable. This does not include the half trimmed and splittings. By "value per cubic meter of matter" is meant the value of the qualified mica per cubic meter of material excavated; i.e. both waste and pegmatite. This is the figure that should be used to determine whether the operation will be profitable or not, as the cost of stripping is about $0.14 per cubic meter. With new machinery not subject to breakdowns, the cost per cubic meter should be around $0.10 to $0.15. To this should be

Jan 1, 1948

By Edward N. Trump

Extensive beds of rock salt occur in New York, Michigan, Kansas, and Texas. Wells are drilled through the beds, cased, and equipped with a suspended center tube. By circulating water through such a well, the soluble saline is dissolved and a brine produced. Operation of a well results ordinarily in the formation of an inverted conical cavity in the saline, inasmuch as the dissolving action of the fresh water is more rapid at the top of the bed than at the bottom. Under continued operations, the side wall of the cavity becomes so flat that a blanket of mud is deposited thereon and if the bed is overlain with shale or a soft rock caving follows. Three methods of operating wells have been employed—the "Tully plan," "the Detroit plan," and "the Trump plan." Both the Tully plan and the Detroit plan involve the formation of the aforesaid conical cavity with constant caving of shale above and deposition of mud on the side wall; the Trump plan was developed to avoid both these circumstances and thus materially prolong the life of a well. Details of the three plans follow. The Tully Plan In the Tully plan, the water passes down the annular space between the casing and the center tube, the brine rising in the center tube (Figs. I and 2). An inverted conical cavity is formed, the side wall of which relatively soon becomes so flat that it is blanketed by mud and impurities from the rock salt; this blanket limits dissolving action to the perimeter of the base of the cone, situated at the top of the saline bed. Caving of the overlying strata follows, and the total production of brine from the well is comparatively small. The Detroit Plan In the Detroit plan, the water passes down the center tube, the brine rising in the annular space between the center tube and casing (Figs. I and 2). Initially, this flow forms a pear-shaped cavity in the bottom of the salt bed, but this cavity soon changes in shape to that of an inverted cone, as under the Tully plan, with the attendant disadvantages inherent in that plan. Application of the Detroit plan is limited to salt beds 300 ft. thick as a minimum. This depth of bed is necessary to prevent fresh water of lower specific gravity than the brine from rising in the

Jan 1, 1948

By Warren E. Wilson

The transportation of solids in pipe lines is a matter of deep concern in many fields of engineering. Much experimental and theoretical work has been done in an effort to devise means of designing pipe lines that will satisfactorily transport given solid loads, but there remain many unanswered questions in this field. The present discussion will be confined to a rather narrow portion of this field and will endeavor to point out certain factors that may well be considered when comparing the relative economy of various installations. The data have been presented previously but a new interpretation was prompted by a suggestion in a paper by Professor O'Brien,1 of the University of California, that the friction work per pound of dry material should be considered in determining the relative efficiency of various installations. This method of considering relative economy in various pipe lines leads to some rather unexpected conclusions, especially with reference to the economy of large pipe sizes. A previous suggestion by the writer3 concerning the economy of a rather peculiar type of installation is strengthened. It is not believed that the considerations set forth herein apply directly in the case of dredge lines, where economy is largely a matter of a high rate of pumping in order to reduce the unit overhead charge. However, it is believed that some value may be gained from these considerations in cases involving the disposal of a fixed amount of solids per unit time with a minimum expenditure of energy and at a low cost for replacement of worn pipes. Such situations are not uncommon in the disposal of mill tailings and the disposal of solids deposited from irrigation waters. It was found that data leading to general conclusions for various pipe sizes were not available but certain definite trends are indicated and methods of analyzing available data are presented in the hope that they may be of assistance in preparing engineering estimates on designs of pipe lines of the type described above. Energy Requirements Carrying out the idea contained in ' Professor O'Brien's paper concerning the method of computing energy required to transport solids, the following analysis leads to some rather interesting conclusions. Let us represent: Solids load in term of mass per unit time by W Ratio of mass of suspended solids to total mass of mixture flowing by p Volume rate of flow of mixture by Q Length of pipe by L slope of energy grade line by s Mass per unit volume of solids by m. Mass Per unit volume of liquid by mi Mass per unit volume of mixture by mm We then have as an expression for the solids load: W = pQmm The work done per unit mass, P, on the mixture to move it along the pipe the

Jan 1, 1948

By Geoffrey Gilbert

The Montana Phosphate Products Co., subsidiary of the Consolidated Mining and Smelting Company of Canada, operates three phosphate properties north and northeast of Garrison, Powell County, Mont. Production of all three is from the same phosphate bed, a 3 to 4-ft. member of the Phosphoria formation, whose outcrop is traceable across the mountains of the Garnet Range in a series of southeasterly pitching folds. Because of topographical differences and of variations in the attitude of the bed, each property has its own mining methods and problems. Most of the phosphate rock produced since 1930 has been shipped to the plant of the Consolidated Mining and Smelting Co. at Trail, B.C., where it is treated with sulphuric acid for conversion to phosphoric acid, which in turn is used to produce various fertilizers. History The occurrence of rock phosphate in Montana has been known since 1910, and the Garrison area was mapped by the United States Geological Survey in 1913. In the nineteen twenties William Anderson, owner of a ranch 8 miles north of Garrison, discovered phosphate on his land, and the Montana Phosphate Co., which later became the Montana Phosphate Products Co., was formed to work the deposit. Montana Phosphate Products Co. later obtained United States leases on two adjoining parcels of ground, and this combined property, known as the Anderson mine, has been the main source of Con-solidated's phosphate rock. The mine now includes an adjoining parcel leased from Anaconda and mined from the Anderson workings. In 1940, the Graveley mine, a small privately owned property 6 miles east of the Anderson, was leased from the owner by Montana Phosphate Products Co., and a U. S. lease held by Graveley on some adjoining ground was subleased. In 1943 the Luke mine, on the Mineral Hill property, 1 3/4 miles south-southwest of the Graveley, a U. S. lease, which previously had produced a few thousand tons, was optioned from the lessees by Montana Phosphate Products Co., and is now being developed. At both these mines the rock is appreciably higher grade than at the Anderson mine. Geology The Phosphoria formation is the Permian member of an extensive sequence of Paleozoic and Mesozoic rocks. It is underlain by Pennsylvanian (Quadrant) quartzite and Mississippian limestone, and overlain without any marked unconformity by Jurassic (Ellis) shale and Cretaceous shale and sandstone. In the Garrison area, the Phosphoria itself consists mainly of about 50 ft. of gray to yellow chert. Immediately below the chert is the phosphate, usually 3 to 4 ft. thick. Below the phosphate occur a few

Jan 1, 1948

By P. de Vitry, Willis P. Mould

The wire saw is a tool not less than 60 years old, probably nearer 100 years old. It was developed in Europe and is reputed to have originated in Belgium. Frombold is said to be the original patentee. Wire sawing equipment, as indicated in Fig. I, is very simple. It consists of a three-strand wire cable, usually pis or 1/4 in. in diameter, or a single flat ribbon of medium hard, tough, alloy steel twisted into a helix of those diameters, made to form an endless belt of any length up to several thousand feet. The wire is guided into the cut by sheaves mounted in slides on steel columns situated close to either end of the cut. The feed motion usually is controlled either by gravity or by hand-operated feed screws. The steel columns or "standards" range from 15 to 30 ft. in length. At the top is a swiveled arm supporting a sheave similar to the traveling sheave below. Immediately under the swivel-mounted sheave is a guy plate or collar with shackles attaching four chain or wire-rope guys with suitable tightening devices, or with two guys and two jack legs for supporting the standard vertically or at any desired anale. The usual drive is by a 10-hp. motor through a gear reducer, on which are Insti- two grooved sheaves, One of which is keyed and the other free running On the shaft. Tension is provided by a car running on a track in line with the driving sheave

Jan 1, 1948