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By James R. Coldwell

Mining and processing cost analyses were conducted by the U.S. Bureau of Mines on massive sulfide copper-zinc and low sulfide vein gold deposit types that may be found in the Ketchikan Mining District. Reserves and recoverable metal values (RMV) needed to make these deposits economically viable were modeled. Methods for estimating ore grades and required RMV are presented. Economic modeling for massive sulfide deposits indicated the RMV necessary for a 15% Discounted Cash-Flow Rate-Of-Return (DCFROR) for an underground cut-and-fill mine ranged from $137/mt for a 6,100 mtpd on-site milling operation to $526/mt for a 450 mtpd off-site milling operation. On-site milling was always less costly than off-site milling. Economic modeling for low sulfide vein gold deposits indicated the RMV necessary for a 15% DCFROR for an open-pit mine, off-site mining operation ranged from $S4/mt at 2,900 mtpd to $71/mt at 360 mtpd, and from $49/mt at 2,900 mtpd to $100/mt at 360 mtpd for an on-site milling operation. Off-site milling was less costly than on-site milling until production exceeded approximately 1,700 mtpd. Then, economies of scale reduced operating costs enough to offset the higher capital costs required for on-site milling.

Jan 1, 1995

By Otto Ruhl

"INTRODUCTION With the conclusion of the war and the ensuing readjustment of industry to peacetime conditions, the Bureau of Mines recognized that definite and complete figures on the reserves of zinc and lead ores in the Tri-State District would be needed for an evaluation of the problem of reconversion. In October 1945 its engineers began examination of all the mines and pros¬pects in the Tri-State area and assembling of the basic data for a complete detailed estimate of the reserves of the field. Six to twelve months will be required to complete the report with the personnel available; therefore, it has been deemed advisable to provide as much data as possible for imme¬diate use. Accordingly, a confidential report prepared in January 1944 for the use of and in cooperation with the War Production Board has been brought up to date to form the basis of this preliminary estimate of reserves.The 1944 report has been revised by first subtracting from the reserves then set up for each mill group the amounts mined and milled by those properties for 1944 and 10 months of 1945, with November and December estimated. These production statistics were taken from the monthly reports of the Metal Economics Division of the Bureau of Mines. The remaining reserves were then adjusted by additions of tonnages of new reserves disclosed by developments during the years 1944 and 1945. Such additions were based upon the data furnished by various operators, upon estimates supplied by the Federal Geological Survey District Office at Miami, Okla., and upon estimates of the engineers of the Bureau of Mines Joplin field office.It is apparent from the work so far accomplished in the detailed exami¬nations now under way that the final estimate of reserves will probably be somewhat greater and will differ to a certain degree from these preliminary totals, not only as to the tonnages of ere but also as to grades and distribution by areas. This is due to the fact that all the factors of development, exploration, and geology are being considered in the present examination and report for each individual mine and prospect, whereas the previous reports covered only the immediate development factors surrounding each mill group then in active operation or projected for operation at some early date in accordance with the possible needs for war production."

Aug 1, 1946

By Raymond B. Ladoo

"The recent discovery and exploitation of petroleum territory have resulted in the enactment of new petroleum laws in most of the South American Republics. The activities in the discovery of these new fields were engendered by the knowledge of the fact that present producing fields must within well defined periods be exhausted. Oil operators were willing to take the initial steps in exploitation in the absence of legislation that applied strictly to petroleum operations. The enactment of modern legislation in many of these Republics encouraging and protect¬ing exploitations may cause tremendous oil activities in these countries, and the results may be comparable with the magnitude of the undertakings and the prestige of the companies now entering this territory.These, oil fields are admirably located for convenient distribution of petroleum by water to all the Nations using oil as fuel for shipping and industrial concerns. The oil markets of the western coast of South America will derive immense benefits from the Panama Canal. This navigation route brings these markets into direct ocean shipment with the Atlantic coasts of the Western and Eastern Hemispheres.One deterrent to oil production in the Republics of South America is the want of inland. transportation facilities, but the recent laws of these Republics without exception provide for acquiring rights of way for pipe lines and other modes of transportation; and doubtless the great interests and. syndicates already operating in these regions will, as production increases, provide ample pipe line transportation sufficient to convey to the coast the oil produced. It way be assumed, from the legal guarantees afforded, and from operating equipment and machinery that are now being concentrated that refineries will be erected at shipping points for the purpose of making these petroleum products accessible to the world."

May 1, 1921

By R. R. Wells

As a part of the strategic minerals program of the Bureau of Mines, nine chromite-ore samples were obtained during the period 1949-56 from mines in the vicinity of Red Mountain, near Seldovia, Kenai Peninsula, Alaska. This report summarizes the results of beneficiation studies of the samples at the Bureau's Juneau, Alaska, and Albany, Oreg., laboratories. In general, the ores were found amenable to concentration by gravity methods for producing concentrates that assayed over 48 percent chromic oxide. Intimate association of chromite and gangue minerals, however, necessitated fine grinding and limited the amount of chromite recoverable. Recovery of chromium in concentrate that assayed 48 percent chromic oxide or higher ranged from approximately 20 percent for low-grade ores (10 to 12 percent Cr203) to more than 95 percent for 1 high-grade sample (42 percent Cr203). The iron content of the chrome-bearing mineral -hence, the chrome/iron ratio of finished concentrate -appears to vary with the grade of the ore. Concentrates made from high-grade ores had chrome/iron ratios as high as 3.1:1; the concentrates from low-grade ores, however, had chrome/iron ratios as low as 1.8:1.

Jan 1, 1957

By A. N. Fried

One of the important problems confronting oil producers in appraising the possibilities of secondary recovery in many California fields is the effect of viscosity on oil recovery by water flooding. In January 1954 there were 554 fields and/or pools, in the State, that produced 1 million barrels daily, and 138 of these pools produced approximately 267 thousand barrels daily of heavy crude oil having gravities below 200 API. Many of these fields are nearing the end of their primary economic life and still have high residual-oil saturations, a favorable factor in water flooding. The crux of the problem is whether or not enough oil can be recovered from these fields by water flooding to make the operation economically successful. Some experiments on the relationship between viscosity and oil recovery have been made by other investigators, but in most instances the viscosity of the oils used in the experiments was lower than the viscosity of the oils found in many of the heavy-oil fields in California. A study was undertaken, therefore, to determine the relationship between oil viscosity and recovery over a wider range of viscosities and to compare the experimental results with those predicted by theoretical calculations.

Jan 1, 1955

By Spencee L. Willett

In 1984, at the request of the Bureau of Land Management, the U.S. Bureau of Mines conducted mineral surveys of the 20,508-acre Blue Lakes (NV-020-600) and 5,142-acre Alder Creek (NV-020-600D) Wilderness Study Areas (WSAs) in northwestern Humboldt County, Nevada. The WSAs are part of an upthrown, north-south trending fault block associated with the Basin and Range province. Both areas are predominantly underlain by the Cretaceous Duffer Peak pluton which intrudes Triassic metasediments and Jurassic plutonic rocks to the east and Permian Happy Creek volcanics to the south. In the Alder Creek WSA and in the southwest portion of the Blue Lakes WSA, Duffer Peak granodiorite and Happy Creek volcanics are overlain by Tertiary basalt. No active mines exist within the Blue Lakes WSA; but, several prospects, claims, and mineralized outcrops are in the south and northeast portions. No mineral resources were identified but samples from discontinuous, vein-type deposits contained anomalous amounts of gold, silver, copper, lead, zinc, molybdenum, antimony, and uranium. Very fine, residual gold was detected in nine alluvial samples collected from a small deposit in the southwest corner of the WSA; average gold value was $3.58 per cubic yard (at $350/ounce). Two mines, several prospects, and mineralized outcrops adjacent to the Blue Lakes WSA contain mineralized, irregular structures which do not appear to extend into the Blue Lakes study area.

Jan 1, 1986

By Charles Sabine

In 1984 and 1985 at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied a 27,420-acre part of the 36,600-acre Southern Inyo Wilderness Study Area, CA-010-056, in order to evaluate the mineral resources. The study area is located in Inyo County, CA, near the town of Lone Pine, about 180 miles north of Los Angeles. The study area takes in most of the western slope of the southern Inyo Mountains. Terrain is steep and rugged; the climate is arid. The study area is underlain by folded and faulted marine sedimentary rocks dating from Ordovician to Triassic, Triassic volcanic rocks, and Jurassic to Cretaceous plutonic rocks. Most mineralization was along faults and shear zones in sedimentary rocks. The study area includes most of the Russ and Lone Pine mining districts which produced over one million dollars in gold, silver, lead, and zinc, mostly between 1860 and 1890. A few mines produced ore as late as 1951. Most production was from the Reward, Silver Spur, Long John, and Pennsylvania mines which are outside the study area. Presently, there is no mining activity in the study area; some development work was done at the Reward mine between 1981 and 1984. Dolomite marble is quarried from the base of the range outside the study area. There are currently about 70 mining claims in the study area.

Jan 1, 1986

By Robert L. Thorne

Cassiterite deposits on Sullivan Creek in central Alaska were investigated by the Bureau of Mines in the spring of 1943. Gold miners in the area have been recovering cassitorite each season as a byproduct of gold placer operations. Approximately 300 tons of tin concentrates have been shipped from the district. The deposits were sampled though trenches and small shafts. An average tin content of 0.28 pound per cubic yard was indicated. A detailed description of sampling methods and sample analyses is presented in this report.

Jan 1, 1948

By Michael S. Miller

In 1985, at the request of the Bureau of Land Management, the Bureau of Mines studied a 50,57U-acre portion of the 90,345-acre Twin Peaks Wilderness Study Area (CA-020-619A) in order to evaluate its identified resources. The area studied is located about 45 miles northeast of Susanville, CA, in Lassen County, CA, and Washoe County, NV. The area is underlain by Tertiary volcanic, volcaniclastic, and intrusive rocks. Quaternary stream, lake, and landslide deposits overlie the older rock. There are no mines or mining claims in the study area. One mineral resource, pozzolan, was identified. Mining claims, inactive in 1985, have been staked adjacent to or near the northwest corner of, and also southeast of, the study area. Examination and sampling of 17 mineralized sites, delineated mostly by prior geochemical surveys, showed at least 30 million tons of subeconomic pozzolan resources and small or low-grade occurrences of gold, silver, copper, lead, zinc, nickel, molybdenum, zeolites and clay.

Jan 1, 1986

Construction workers may be exposed to hazardous dust containing crystalline silica during site preparation when drilling systems are used. The National Institute for Occupational Safety and Health (NIOSH) found that drill dust could be decreased by using wet or dry dust reduction engineering controls, enclosed cabs, and implementing a dust control program.

Jan 1, 2009

By d&apos, Kathleen J. Amico

THIS summary appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S mineral production also is included.

Jan 1, 1964

By H. W. Kilau

The U.S. Bureau of Mines examined the wettability of bituminous and subbituminous coals before and after exposure to ambient air atmosphere, as part of an ongoing project investigating the coal-wetting abilities of surfactant solutions intended for the suppression of dust during coal mining operations. Exposure periods were generally 7 days or less, and the changes in wetting response were measured with a capillary penetration apparatus. Wetting solutions tested included a nonionic surfactant, two anionic surfactants, and pure distilled water. After exposure, higher ranked bituminous coals treated with nonionic surfactant solution and pure water showed increased wettability, but lower ranked subbituminous coals showed decreased wettability. With the anionic surfactants, the coals demonstrated opposite responses. The wettability changes appeared to be related to the coal moisture content. These changes may be amplified by specific, but incompletely understood, interactions between surfactant polar groups, absorbed water, and the coal surface.

Jan 1, 1989

By Robert J. Willard

This chapter includes tables from 1983 that were not available in time for publication of the 1983 Minerals Yearbook, but does not include corresponding tables for 1984. The value of raw nonfuel minerals produced in the United States during 1984 was estimated at $23.2 billion, an increase of $2.1 billion over the value for 1983. This is the second consecutive year that the value has increased, and except for a decrease in 1982, the value for each year has increased since 1971, or 12 out of 13 years. In 1984, 16 out of 21 metal commodities increased in output while 5 metals decreased; 14 metals increased in value and 7 decreased. Of 46 nonmetal commodities. 37 increased in output while 7 decreased and 2 remained unchanged; 35 nonmetals increased in value and 11 decreased. These statistics are grounds for continuing the cautious economic optimism expressed in 1983. Despite the note of optimism, however, numerous problems plague the mining industry, weakening its stability and inhibiting its growth potential. The problems are a complex mix of international and domestic factors that have been building in the recent past, but have become even more troublesome in 1984.

Jan 1, 1985

By Walter W. Kaufman

This report summarizes a study conducted to determine the state of the art of various rock removal systems and their capabilities. The Objective of the study was to determine if currently manufactured equipment can adequately accomplish rock removal in surface mine reclamation applications. Evaluations of state reclamation regulations, with regard to topsoil rock content, were made to determine the rock removal requirements. The major categories of equipment studied are rock pickers and rock rakes. The impact of rock removal implementation on the reclamation operations is discussed in detail.

Jan 1, 1979

This Part describes a mine pager phone to public telephone interconnect sys tem that permits mine paging telephones to be selectively interconnected with the public telephone system, as illustrated by Figure 1. This interconnect concept was first conceived and demonstrated in breadboard form by H. E. Parkinson of Industrial Hazards and Communications, PMSRC, as one means for providing improved emergency and off-hours communications. The third-generation prototype unit described in this Part was designed and fabricated by Arthur D. Little, Inc. This unit is a small desk-top or wall-mounted unit that connects directly to both the public telephone line and the mine pager phone line, and requires no modifications to either the public dial telephone or mine pager phones. As part of this task, ADL also built, under a very compressed time schedule, a second-generation prototype unit suitable for reliable demonstration of the interconnect concept during the Bureau's technology transfer seminar on mine communications in March 1973. * A major objective of the design of the third-generation unit described in this Part was that it be compatible with present mine pager phone systems utilizing DC voltage on the mine phone line to activate the phone loudspeakers. Therefore, this unit was designed to operate in a push- to-talk, push-to-listen mode that accommodates the inherent design differences and operation modes of the mine phones of different manufacturers. Though this push- to- talk, push- to-listen mode of operation may seem slightly unusual at first sight, we have found it is easily learned by new users. However, mine phone manufacturers wishing to expand their product lines with such an interconnect system will probably find it to their advantage to customize the design of this system to their particular mine phones, thereby utilizing the unique attributes offered by their individual product lines. This customization should not be difficult, and Section III below suggests some of the features that can be easily added to future designs. Detailed parts lists and circuit schematics for the present third-generation proto- type system can be obtained from the system manual submitted to PMSRC and placed on public file.

Jan 1, 1974

By G. R. Hopkins, E. W. COCHRANE

According to reports received by the United States Bureau of Mines , Department of Commerce , as of January 1 , 1930 , there were 412 completed refineries in the United States with a daily crude oil capacity of 3,755,585 barrels . This compares with 413 refineries of 3,509,540 barrels capacity on January 1 , 1929 , which indicates that whereas the number of refineries was practically unchanged , the total capacity increased 8 per cent during the past year . Of the completed plants as of January 1 , 1930 , 358 plants , of 3,634,825 barrels total capacity , were operating and 54 , with a capacity of 130,760 barrels , were shut down . Compared with a year ago , this indicates a decline in the percentage of the total refinery capacity that is inoperative . There has been a decided decrease in the number of shut-down plants since 1924 and 1925 , when one plant in every three was inoperative . Many of the inoperative plants of 1924 and 1925 were constructed soon after the boom times of 1920. Some of these were operated for a time but were unable to show a profit during 1923 and 1924 , when an overproduction of crude petroleum was accompanied by demoralized markets for refined products . Prices for refined products improved in 1925 and 1926 , but only a comparatively few of the shut -down plants , then partly obsolete , were able to obtain or renew their crude connections and compete successfully with the larger , more firmly established refineries . After five years or more of continuous idleness , a refinery would be rendered practically useless through corrosion and obsolescence . Consequently , most plants now being carried as " shut -down " have operated intermittently since 1923 . struction . A material change occurred in 1929 in the matter of plants under con- On January 1 , 1929 , there were 14 plants under construction , with a potential capacity of 99,000 barrels per day , whereas on January 1 , 1930 , there were only eight plants of 37,200 barrels capacity being built . This decline was due to the fact that the construction program in west Texas , which was at or near its height on January 1 , 1929 , was completed prior to January 1 , 1930 .

Apr 1, 1930

By J. H. East, D. Harrington

Fires in metal mines have resulted in some of the worst disasters in American mining history insofar as loss of life is concerned. One fire caused the death of 163 miners and individual less spectacular fires have cost the lives of scores of workers. Metal mines are often very deep, and the men working on numerous levels far removed from direct communication with the surface. In many instances they cannot be warned quickly of an emergency or a mine fire by telephone or other usual method of communication, or by messenger, flashing lights, gongs, sirens, or whistles. Telephones are not paricularly effective as a means of warning unless placed at all strategic points and with attendants always on duty; though telephones well placed have a definite value in any well-pla.mied emergency procedure in mines of all kinds. Messengers are slow and men working in remote parts of a mine would not receive a warning quickly enough. Most metal mines are not electrically lighted, except at or adjacent to shaft stations and in principal haulageways, and this limits the effectiveness of flashing lights. Electric gongs and sirens or whistles have been tried as warning signals, but the sound is quickly deadened and does not travel upward into the stopes, especially those of an extensive volume. Shutting off the compressed air is by no means satisfactory as a warning, as not infrequently it is stopped accidently, so that it loses its value as an alarm. The introduction of water into compressed air lines is undesirable as a fire warning and necessitates considerable care, especially in deep mines; pressure-reducing valves must be provided to reduce pressure that otherwise would break connections or split the pipe. A quick, effective method of warning miners underground of the existence of an emergency requiring them to leave the mine immediately, such as a fire on the surface or underground, is provided by the introduction of stenches in the compressed-air lines. This method of warning is by no means experimental, inasmuch as it has been used successfully for many years in

Jul 1, 1943

By Clayton M. Rumsey

In 1984, the U.S. Bureau of Mines conducted a mineral survey of a 26,598-acre study area which includes the 23,702-acre Mt. Limbo Wilderness Study Area (NV-020-201). The study area is 65 miles northeast of Reno, NV, and is underlain mainly by Cretaceous granodiorite that comprises the Selenite Range. Tertiary basalt, rhyolite, and sedimentary rock as well as Quaternary alluvium and lake deposits are exposed near the study area boundary. Mines just north of the area in the Hooker mining district produced tungsten ore in the 1940's and 1950?s. Similar deposits are not known in the study area. Disseminated gold is in sinter about 6 miles west of the study area and at several other locations regionally.

Jan 1, 1986

According to industry representatives, U.S. producers were listing unalloyed 95.5 percent aluminum ingot in October at 53-57.5 cents per pound, but reportedly much is being priced at 53 cents. New York dealers raised their October positions by about 3 cents to 56-56.5 cents, mainly to cover spot supply shortages. London Metal Exchange 3-month forward contracts traded up in October from 52.3 to 57.3 cents per pound and closed at 56.4 cents. ASBESTOS The Jaquays Asbestos Corp. has announced the imminent closure of its mine and mill in Globe, Arizona. This is the last asbestos producer in the State having operated continuously, except during the early thirties, since 1914. Cost of compliance with environmental regulations was given as the reason for closure.

Jan 1, 1978

By Robert G. Bottge

Hard rock mining has grown in importance in the Yukon Territory during the last 10 years while Alaskan hard rock mining has declined. One asbestos deposit in Alaska is dormant, but an asbestos deposit 55 miles to the east in the Yukon Territory is being mined by the Clinton Mine Div., Cassiar Asbestos Corp., Ltd. In this Bureau of Mines report, the economics of mining in the two locations were derived using the Clinton mine as a model. Both deposits were assumed to be of equal size and mined by similar methods. Conventional open pit mining and processing methods were assumed, and capital and operating costs were derived using flowsheets and standard costing methods. The estimated cost for the mine, mill, and support facilities in Alaska was about 30 percent more expensive than that in the Yukon Territory. The higher labor rates in Alaska were the primary contributor to the higher construction costs; freight rates added only slightly to the total costs. Approximately two-thirds of the additional annual costs of operating in Alaska were for wages and fringe benefits. The price required for the Alaskan asbestos fiber was $356.65 per ton compared with $287.44 for Yukon fiber, plus or minus 20 percent. A 12 percent discounted cash flow rate of return, 100 percent equity financing, and a rapid writeoff of assets were assumed.

Jan 1, 1975