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By Raymond P. Maloney

The Bureau of Mines investigated the White Mountain mercury deposit, in the Kuskokwim River Basin, to better determine the extent of mercury mineralization and to encourage its development by private industry. A program of diamond drilling, augering, bulldozer trenching, and sampling was carried on during four field seasons, from 1960 to 1963, inclusive. Significant amounts of cinnabar, with only trace amounts of arsenic and antimony, occur in dolomite over an area about 4,000 feet long and 1,500 feet wide. The deposit differs from other mercury deposits in the Kuskokwim River Basin by the absence of silica-carbonate and rhyolite intrusives. Small-scale mining was started in 1963 as the result of Bureau investigation and continued during the summers of 1964 and 1965. The investigations indicate that open pit mining might be the most feasible method of working this deposit.

Jan 1, 1967

By A. W. Fahrenwald

The purpose of screening is to separate a crushed or natural product into one or more products in which size of grain is constant, or within certain size limits. The ore dresser finds need for this operation in the laboratory, in the study of ore-dressing processes, and for various purposes in the plants. In the plant, for example, screens are employed in closed circuit with crushing devices such as rolls, and sometimes are used in closed circuit with ball mills. Screens are generally used to prepare jig feed where a sized feed is wanted. For any given sieve opening there is in any feed a certain percentage of grains that will pass through the sieve meshes only with difficulty and under favorable conditions. For example, cylindrical grains of length greater than the maximum dimension of the sieve mesh and of diameter less than the sieve opening pass the sieve only when the long axis of the grain is normal or nearly normal to the sieve. Whether such grains should actually be in the through's or the oversize of a screening operation--considered from the point of view of the subsequent treatment of the grains--can not be said. The grains that pass the sieve opening in a screening process only under-favorable conditions have been named "difficult" grains by R. K. Warner.4 In many ore-dressing flow-sheets it probably matters little whether these difficult grains show up in the screen through's or oversize. The main objection to them is that they are sieve-blinding.

Jan 1, 1929

By B. K. Cantrell, K. L. Rubow

"Two source apportionment techniques have been applied by the Bureau of Mines to aerosol measurements in diesel equipped underground noncoal mines. The first technique is based on size selective sampling and the premise that the diesel exhaust fraction of the aerosol is predominately sub-micron in size while the mineral dust fraction of the aerosol is mostly super-micron in size. The second technique, Chemical Mass Balance (CMB) modeling, was used to referee the analysis of diesel and mineral dust aerosol concentrations with the size selective method.The size distribution data were modeled using a log-normal regression to parameterize the sub- and super-micron fractions of the sampled aerosol and to estimate the mineral and diesel contributions to each. For the mines visited, analysis of the size selective: samples yielded an average value for the fraction of the fine aerosol attributable.to mineral dust of 3 pct.'The CMB analysis, applied to both fractions of the respirable mine aerosol, yielded the amount contributed to each by the diesel· and dust aerosol sources. Less than 5 pct of the sub-microm fraction was mineral dust, however, as much as 20 pct of the diesel aerosol was found: ""in the super-micron fraction requiring a correction of the sub-micron fraction to account for the missing diesel mass. More accurate measurement will require a carbon specific analysis of the aerosol."

Jan 1, 1988

By W. D. Musgrove, B. W. Gandrud, A. C. Richardson

"INTRODUCTION The Cahaba coal field is the second largest coal—producing area in Alabama. This field underlies parts of Shelby, Jefferson, St. Clair, and Bibb Counties and has an area of about 270 square miles. The Cahaba formations contain a number of coal beds, about 8 of which are mined at present. Although the area contains many folds and faults, samples from various mines and beds indicate that, except for the variation in ash content, the coal from this field is very uniform in character and quality. It is a high-volatile bituminous coal used chiefly for steam-raising purposes and domestic fuel. The coal as mined usually contains too high a percentage of impurities to be marketed without some preparation. The majority of the mines have washing plants in which jigs are the favorite type of equipment, although at some mines tables are used for cleaning the slack sizes. The washing characteristics of the coal from the Cahaba field are very uniform and differ from those of the near-by Warrior field, in that the coarser sizes contain a much lower percentage of bony material than the finer sizes. In general, the bone increases with decrease in size. It breaks into thin flakes, making difficult its elimination in the cleaning process, and gives rise to what is known among the washery operators of the Cahaba field as the ""rash problem.""A previous publication 5 referred to rash from the standpoint of jig operation and suggested some means of handling it with jigs. This report presents the results of table tests on two samples of fine coal from the Thompson and Woodstock beds, respectively, of the Cahaba field to determine the influence of rash on table efficiency.This investigation has been made in connection with the study of coal-washing problems now being conducted by the U.S. Bureau of Mines and the University of Alabama, with the cooperation of the different coal operators of Alabama."

May 1, 1934

By Albert W. Deurbrouck

This report describes preparation characteristics of significant coalbeds in Tazewell County , Va . In 1961 Tazewell County produced 933,110 tons of clean coal from six coalbeds ; the Lower Banner , Raven , Jawbone , Upper Seaboard , and Pocahontas No. 3 and No. 5. Samples from all of these beds , except the Lower Banner , were included in this study plus a sample from the Pocahontas No. 4 bed . Of the samples collected , only one would require upgrading to be of metallurgical quality . The coals ranged in rank from high- volatile -A to low- volatile bituminous .

Jan 1, 1963

By A. W. Deurbrouck

This report describes the preparation characteristics of the significant coalbeds from which samples could be obtained in Webster County, W. Va. In 1964, approximately 825,000 tons of coal was produced in the county, of which 732,000 tons was mechanically cleaned in three preparation plants. The Sewell coal bed accounted for 94 percent of the coal produced. Twelve samples were collected from five coalbeds. Four of the samples would require upgrading to meet metallurgical requirements; two others of just over 8.0 percent ash would require some upgrading. In general the coalbed samples collected in the county were of medium-sulfur and medium-to low-ash content as received or after removal of the sink 1.58-specific-gravity material.

Jan 1, 1966

By Lester G. Morrel

THE RICH and varied occurrences of metallic ores in Australia, extensive nickel deposits on New Caledonia and phosphate rock on several widely scattered small islands were important aspects of the economy of the South Pacific area. Relatively small quantities of gold and nonmetallic minerals produced in New Zealand, Fiji, and the Territory of Papua-New Guinea remained important to the domestic economies of these islands, but had little importance to overall world mineral supplies. The value of mineral commodities produced in this area in 1964 was estimated at $658 million,3 compared with $585 million in 1963. The year's greatest commodity gains were in bauxite and aluminum, beryl concentrate, manganese ore, nickel smelter products, tin, and coal. Annual increases were recorded in virtually all countries and possessions in the area except Papua-New Guinea, where the drop in output of alluvial gold accounted for a decline of about $160,000. Mineral industry activities in Australia overshadowed those in all other parts of the South Pacific in 1964. Outstanding developments were the sales contract negotiations and physical preparation for exploiting the rich iron ore discoveries in Western Australia, the initiation of domestic crude oil production, the commissioning of two new steal mills and an alumina refinery and a start on the new alumina-aluminum project based on Cape fork bauxite deposits. The principal mineral development in 1864 in New Zealand was the progress on plans of the Newzealand Steel Co. to use indigenous iron sans as the resource base for a local steel industry. In New Caledonia, additions and expansion of the nickel mining and smelting facilities continued throughout the year. Plans for extensive geophysical studies were announced by the Government Geological Departments of British Solomon Islands and Fiji.

Jan 1, 1966

By L. C. IlsLey

Through the cooperation of the Pennsylvania Department of Mines the writer obtained from State, records detailed information concerning coal-mine accidents occurring in Pennsylvania bituminous mines during 1939, particularly those nonfatal accidents in which the injured person lost 60 or more days? time from mark. The writer wishes to acknowledge assistance received from Pennsylvania State officials, especially Richard Maize, secretary of mines, and. Joseph J, Walsh, deputy secretary of mines; also to Thomas Dickinson,3/ of the Bureau of Mines, who rendered valuable assistance in assembling the data an the several tables.

Jan 1, 1941

By George S. Rice, W. L. EGY, H. P. Greenwald, L. M. JONES

CHAPTER I. INTRODUCTION AND SUMMARY. BY GEORGE S. RICE. PREFATORY STATEMENT. This bulletin describes the second series of coal-dust explosion tests conducted by the Bureau of Mines in the experimental mine near Bruceton, Pa. It covers a period from 1913 to 1918, inclusive, of more or less consecutive testing, during which many important conclusions were drawn regarding the way a coal-dust explosion may originate, the mechanism of an explosion, and the methods of pre- venting explosions and of limiting incipient explosions. The manuscript was prepared in 1918, but its publication had to be put aside during the World War for more pressing publications and it was not until this fiscal year 1922 that funds could be allotted for its printing. Meantime the general facts concerning methods of preventing explosions have been made known to the mining industry, with great advantage, it is believed, as explosions of coal dust in mines in the United States have become infrequent. This fact, however, must not lull the consciousness of mining men to the terrible potential danger that lurks in untreated coal dust. The experiments described in this volume should be of aid to them in planning to keep the ever present coal dust in an innocuous condition. The first series-reported in Bulletin 56, "First Series of Coal-Dust Explosion Tests in the Experimental Mine"-included only pre- liminary tests of the ability to start explosions of coal dust under the conditions in the experimental mine. After this fact had been determined and several violent dust explosions had been demon- strated before large audiences of mining men, the work had to be suspended in order that necessary repairs and extensions might be made in the fall and winter of 1911-12. Although the question of the possibility of coal dust causing explo- sions had been considered for more than a century, and much testing in laboratory apparatus and in small surface galleries had been done, coal-mining men generally did not believe that coal dust was explo- sive and considered that fire damp or gases of unknown composition were responsible for the mine explosions that had cost thousands of lives in the various coal-mining countries during the last century. As coal mines increased in number, size, and depth, explosions became alarming in their frequency. Finally came the Courriéres disaster in northern France, 1906, by which 1,100 lives were lost, and the following year in this country, the Monongah mine explosion, in West Virginia, which killed 361 men, and the Darr explosion, in Pennsylvania, which killed 239 men. These two disasters, both in December, 1907, led Congress to make an appropriation for an in- vestigation of the causes of mine explosions. The funds became available July 1, 1908, and the work was placed under the United States Geological Survey's technologic branch, with the late Dr. Joseph A. Holmes in charge. Before undertaking the investigations Dr. Holmes visited Europe, accompanied by the senior author of this bulletin, to study the methods foreign countries used to prevent mine explosions, to obtain details regarding tests being made in several countries, to procure safer explosives and better safety lamps for use in gaseous and dusty mines, and to study the methods used in coal-dust explo- sion tests in the recently completed galleries at Altofts, England, and Liévin, France, and in the older galleries at Gelsenkirchen, Germany, and Frameries, Belgium. At all of these stations the explosions tests were made in surface galleries. The Austrian gallery at Segengottes, near Brünn, Moravia, visited by the writer in 1911, is an underground gallery, but the testing done in it was limited, dealing with ignition of coal dust rather than with propagation. Although the results obtained in the foreign galleries had indicated that coal dust was explosive, mining men in the respective countries were of the opinion that the dust would not explode under mine con- ditions. This situation led Dr. Holmes to the conclusion that testing must be done in a real mine, to make certain that the conclusion would be reliable and would be accepted by the mining public as decisive.

Jan 1, 1922

Lower workers' dust exposures during bag stacking while ergonomically improving the bag stacking process. Approach Install a new pallet loading dust control system which uses a push-pull ventilation technique along with a hydraulic lift table to control the pallet loading height throughout the entire loading cycle. How It Works A low-volume, high-velocity blower system operating at approximately at 120 cfm blows a stream of air over the top layer of bags on the pallet. The blower system is composed of two 3-inch air jets (approximately 1,200-ft/min velocity) directed toward an exhaust system on the opposite side of the pallet. As these air jets travel across the pallet, they en-train dust generated during bag stacking. The dust laden air is then captured by the exhaust ventilation system which draws approximately 2,500 cfm through an exhaust hood on the opposite side of the pallet.

Jan 1, 1989

By Leonard F. Heising

Domestic production of Metallurgical-grade manganese has contributed such a small percentage of the United States industrial demands that areas known to contain large tonnages of low-grade manganese ore have been investigated by the Bureau of Mines to reduce this country's dependence on foreign ores. A major source of low-grade manganese is the Cuyuna iron range in Minnesota. The entire Cuyuna iron range is covered by an overburden of glacial drift that, in some places, reaches depths of 200 feet or more. Prospecting and exploration must be guided by geophysical methods, drilling results, or projections of exposures found in operating mines because there are no outcrops near the productive parts of the range. Past drilling for the purpose of outlining iron ore generally was confined to the highly oxidized zones. Much of the manganese with which the Bureau of Mines is concerned occurs in thin-bedded unoxidized iron formations, too low in iron content to have been of interest to those seeking commercial iron ore. The primary objective of the core-drilling reported here was to obtain cores of different classes of manganiferous rocks and to determine whether or not the samples were amenable to beneficiation.

Jan 1, 1959

By J. W. Miller

Depletion of coals most suitable for metallurgical fuel has nude necessary a general survey of coking-coal reserves in the United States. These investigations were begun in 1948 at the joint request of the Munitions Board, Department of Defense, and a number of coal companies. This report, which is one of a series, by counties, describes the preparation characteristics of the coals of Letcher County, Icy. From these data it is possible to determine: (a) Which coals either as mined or after beneficiation by conventional preparation are suitable under present standards for producing metallurgical coke, (b) which coals require special and more intensive treatment in preparation than is now practiced, and, (c) which coals cannot be upgraded by known commercial preparation methods to metallurgical fuel standards now accepted.

Jan 1, 1955

By Jr. Karr

The Bureau of Mines studied the influence of carbonization method, temperature, and carrier gas on the composition of eight different low-temperature tars produced from a Colorado subbituminous coal. A fluidized bed was compared with an entrained bed, temperature was varied from 500° C to 650° C, and external heating using recycle gas as the carrier gas was compared with internal heating using oxygen-containing gas. The entrained bed yielded significantly more m-cresol and m-ethylphenol, indicating that thermodynamic equilibrium was more nearly approached in the system. Increasing the temperature greatly increased the yield of benzenes and naphthalenes, while paraffins, olefins, and total tar acids were reduced. Using oxygen in the carrier gas decreased the yield of low-boiling phenols and increased that of paraffins and olefins at 650° C.

Jan 1, 1966

By S. H. Lorain

Shortly after the Strategic Minerals Act of 1939 we passed by Congress, the Bureau of Mines was authorized to begin a program of investigation of domestic sources of strategic minerals. Since World War I, the Philipsburg district had been virtually the only one in the United States that was producing manganese on a commercial scale. Consequently, the district was among the first to he investigated. During the summer of 1939, the Geological Survey mapped the geology and ore deposits of the district. In late July 1939 the writer examined the district for the Bureau of Mines. On the basis of this examination and of the work performed by the Geological Survey, the Bureau of Mines diamond-drilled at several properties in the district during the summer of 1940. This report reviews the mining history and geology of the district, and presents the factual data obtained by diamond drilling.

Jan 1, 1950

By William A. Beck

Since bauxite mining began in the Irwinton District, Wilkinson County, Ga., in 1912, it has been on a small scale, as most of the deposits of high-grade ore are small. The bauxite has a high silica content, and its use has been largely limited to the chemical industry. Drilling under this project did not disclose any bauxite deposits of commercial value: However, numerous holes penetrated high-alumina clay deposits, but no attempt was made to delimit them, as the project was solely an exploration for bauxite. Bauxite was first discovered near Irwinton in 1907. The district covers virtually all of Wilkinson County and extends into the adjoining counties of Washington, Baldwin, and Twiggs. Mining was begun in 1912 by the Republic Mining & Manufacturing Co. on the Honeycutt, Parker, and Daniel properties, which are 1.5 miles from Wriley on the old Irwinton to Milledgeville Road.

Jan 1, 1949

By A. D. Hahn

The Federal Bureau of Mines examined ilmenite-bearing sands in southern Texas as part of a program to discover sources of supply for the domestic titanium industry. Deposits were examined from May 1956 through January 1959 in the outcrops of sandstone beds in the Jackson group of Eocene formations in Lee, Burleson, Fayette, and Starr Counties on the Gulf Coastal Plain; in alluvial valley fill in Brewster County in southwest Texas; in the sand beaches of Matagorda Peninsula and the Galveston, Padre, and Brazos Islands--part of the offshore chain of barrier islands along the Texas coast; and in unconsolidated sediments in Willacy County on the Rio Grande delta in the southeast Texas.

Jan 1, 1961

By Wilber Duvall, Leonard Obert

"INTRODUCTION This report is the first of four to be presented on the microseismic method 4/ of predicting rock failure in underground mining. The application of the microseismic method to one specific case, namely, that of predicting rock bursts in deep mining, has been described in two previous reports. 5/ 6/ Since the publication of these reports 5/ 6/ the method has been extended to other fields of mining, end it is the purpose of this report (Part I) to describe the general microseismic method, giving the empirical facts upon it is based, the different testing procedures, the method of recording and analzing the data, and the interpretations that can be obtained there-from. Part II will describe a series of laboratory experiments that were performed to give information on the origin of microceismims and the microseismic properties of various rocks. Part III will cover application of the method to specific mining problems together with a brief description of a number of investigations performed during, the last three years. Part IV will describe in detail the microseicmic equipment used in the various phases of these investigations."

Feb 1, 1945

By William Cochran

Data on the cost and quantity available were developed for rutile (TiO2), which is potentially recoverable as a byproduct at sand-washing plants in the Southeastern States of Alabama, Georgia, North Carolina, and South Carolina. Baaed on 1969 production data, an estimated 4,300 tons of rutile could be recovered annually from plants that process more than 25,000 tons of sand per year. Rutile prices at which this resource would be available ranged upward from $262 per ton, compared with the current market value of $185 per ton.

Jan 1, 1972

By R. C. Anderberg, F. J. Caervenyak, F. J. Frattali, H. J. Kandiner, R. A. Brown

"INTRODUCTION Considerable interest was shown .prior to and during World War II in the winning of metallurgical-grade alumina from anorthosite, kaolin, siliceous bauxites, diasporic clays, and other aluminum-bearing ores. Laboratory and pilot-plant investigations were made on many of these ores by the Bureau of Mines, and a series of reports on them is being prepared. This report covers the tests made on the application of the lime-soda-sinter process to anorthosite, which is a mixture of albite, NaAlS1308, and anorthite, CaAl2Si208. Extensive deposits of anorthosite occur in the Laramie Range in Wyoming and extend into Colorado; other deposits are found in New York, with outcroppings appearing in Vermont, Maine, and Labrador.Anorthosito can not be treated by the Bayer process for the production of metallurgical-grade alumina, because excessive losses of soda and alumina occur from the formation of sodium-aluminum silicate due to the large amount (50 percent) of silica in the ore.RESULTS OF INVESTIGATIONSSmall-scale laboratory tests supplemented by pilot-plant runs have demonstrated that the alunina and soda occurring in the Wyoming anorthosite from the Laramie Range can be extracted and recovered satisfactorily by the lime-soda process. It has been shown that liquors containing approximately 95 gram of A1203 per liter can be consistently produced at Na20:A1203 ratios from 1.75 to 2.27, and that these liquors can readily be desilicated and carbonated to yield high-grade alumina trihydrate of quality comparable to that essential for cell-grade alumina. The optimum results were obtained with Na20:A1203 mol ratio of 1.03 and Ca0:Si02 ratio of 2.14 in the sinter when calcined at an average temperature of 2,444ºF. for 25 minutes."

Nov 1, 1947

By Mark Sheppard

This paper is the third of a series recording the results of tests made at various quarries throughout the United States to determine (1) the relation between the size gradation of feed to, and product from, primary crushers, (2) the particle shape of the crushed. product, (3) the differences in gradation and particle shape produced by different types of primary crushers, and (4) the differences in gradation and particle shape caused by crushing different kinds of stone. Progress reports 1 and 2 dealt with comparisons of different types of crushers crushing the same type of stone. This report deals with relation¬ship between feed and product of two different limestones, as to size distribution and particle shape, when crashed in the same crusher.

Jan 1, 1938