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By B. W. Madsen

Research by the Bureau of Mines has shown that treatment of open pit waste by crushing and sizing followed by flotation of the fines and leaching the coarse fraction results in greater metal recoveries than obtained by leaching only. Tests with a chalcocite-bearing quartz monzonite mine waste sample that had been crushed to minus 6 inches and screened on 1/2 inch yielded copper and silver recoveries of 71 and 22 percent, respectively, by the combined flotation-leaching process, compared with 48 percent of the copper and no silver recovered leaching the run-of-mine material. Copper was more readily leached from the coarse material with the minus 1/2-inch fines removed than from material with the fines included. The improved leaching was attributed to improved permeability and the associated improved circulation of air to the interior of the ore column. Cost estimates showed that the proposed intensive treatment of mine waste will require a greater capital investment and higher annual operating costs than conventional milling and dump leaching process. However, the income from the additional metal production offsets the increase in capital investment and operating costs, resulting in additional profit.

Jan 1, 1975

By Harold E. Heide

The United States is the world's largest consumer of tin and depends entirely upon foreign imports for its major source of supply. Only a small quantity of tin is produced on the North America continent. The advent of the war in Europe in 1939?brought a threat to our foreign sources of supply, and the Congress took steps to forestall shortages of tin and other metals. By authority of the Strategic Minerals Act, passed by Congress in 1939, and subsequent legislation, the Bureau of' Mines ?and Geological Survey conducted investigations of domestic tin deposits. Most of the tin that has been produced in North America came from the Seward Peninsula, Alaska.

Jan 1, 1948

By M. W. Von Bernewitz, J. J. Forbes

"In the United States there are hundreds of underground and surface (inside and outside) inclines at coal mines on which trips of cars are continually being run with coal, rock, supplies, and men. The safety of the men and prevention of damage to the slopes depend, excluding the personal element of the hoist-man, on the strength and condition of the wire cable, draw bars, and the couplings, and on the links of chains and pins as well. Within a recent period of four weeks there have been two runaway trips, one on the surface and one underground; it seems desirable to call attention of mechanical engineers and others at coal mines to the need for closer and more frequent inspection of the cable, draw bars, coupling links and pins, derailing devices, wheels, brakes, and other parts of cars or trips on which men are hauled on inclines. This bureau has never published anything on this class of accident heretofore.How frequently runaway trips occur is not known. If no serious injury or fatalit has to be reported to the State authorities, a number of such happenings may occur and not be mentioned outside of the immediate vicinity of the mine.Runaway trips can and do result in considerable loss of life, in injuries, and damage, either at or near the place of the break, or throughout a mine by causing an explosion of gas or coal-dust or both, This report is restricted to a study of the mechanical and physical phases of car trip construction and of the metal of couplings and ropes; derailed trips are not included and may be the subject of another paper. There is no need to mention gas accumulations, coal-dust and rock-dusting, open lights, protected power lines, and permissible equipment, because these have all been well covered in Bureau of Mines publications which have been widely distributed and partly or wholly reprinted by others.Most of the items regarding the runaway trips tabulated have been abstracted from reports made respectively by Clarence Hall, W.O. Snelling, and J. W. Paul; D. Harrington and J. J. Forbes; H. C, Howarth and G. S. McCaa; K. L. Marshall and E. H. Denny; J. J. Forbes, G. W.- Grove, and R. D. Currie; S, P .Howell and K. L. Marshall; and .J. W. Paul, H. D. Mason, and G. E. McElroy, all of the mining and safety divisions; and C. H. Herty, jr., and G. R. Fitterer of the metallurgical section of the Bureau of Mines. W. J. Fene, K. L. Marshall, and S. P. Howell of the safety division, and J. F. Lessig, mechanical engineer, and G. St. J. Perrott, superintendent, Pittsburgh Experiment Station, read the text and offered sugges¬tions. W. J. McGregor, coroner for Allegheny County, and P. F. Nairn, State Mine Inspector of Pennsylvania, contributed valuable information."

Mar 1, 1931

By Benjamin W. Haynes

As part of the first-order assessment of potential manganese nodule processing reject waste materials, the Bureau of Mines estimated the physical and chemical characteristics of reject waste materials that would be generated from each of five potential process flowsheets. These processes were chosen because of their economic and technical feasibility for first-generation nodule processing. A brief description of the five processes is given to show process inputs and outputs, The physical characteristics are predicted based on land-based laterite processing where applicable, and where no land-based analog exists, on the basis of process chemistry. The probable chemical characteristics such as element content and compound form are tabulated for each process for 16 elements: As, Ba, Be, Cd, Go, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, TI, and Zn. These elements were chosen based on their presence on the toxic substance list of priority pollutants, EP toxicity criteria, and major and minor elements of economic importance (Co, Fe, Mn, and Mo). Physical and chemical analyses as well as results of the EP toxicity test of one industrially supplied pilot plant reject waste material are presented.

Jan 1, 1982

By Rov G. Stott

In recent years there has been no loss of life from fires in the underground mines of the Lake Superior district, but numerous minor fires and several serious ones involving loss of property and production have occurred. The iron-ore-producing companies recognize that well-equipped mine rescue stations are a valuable asset against the ever-present ranger of mine fires or the possibility of hazardous atmospheric conditions underground. Prompt action by trained and properly equipped rescue teams is recognized as the prime essential in saving lives, property, and production when fires occur. To achieve this purpose, the mining companies have provided themselves with mine rescue equipment and maintain trained mine rescue crews. This circular describes how one progressive company has provided, maintained, and improved upon such protection for its underground iron-ore mines on the Marquette and Menominee iron ranges of Michigan's upper peninsula. SUMMARY The central mine rescue station of The Cleveland-Cliffs Iron Co. at Negaunee, Mich., has provided the company's mines with competent and well-equipped mine rescue teams. The new central mine rescue station at the Mather mine "B" shaft has the distinction of having underground training facilities provided as a part of the station. The company maintains the largest trained force in mine rescue in the Lake Superior district, and mine rescue training is employed as a part of the accident-and fire-prevention program. One of the most important results has been the promotion of closer cooperation and understanding between the management and the workmen. In addition to the service rendered to company mines, the station and its personnel have given assistance to others. The station and its equipment have also been used for training several nearby community volunteer fire departments. This mine rescue station and its personnel have been a dependable and valuable asset to the community in which it is located.

Jan 1, 1954

By G. D. Coe

Float-and-sink tests indicate what results are obtainable by gravity separation and rare therefore an invaluable adjunct to most coal-cleaning processes. However, it is difficult to make a direct interpretation of float-and-sink data on coal, and several systems for interpreting them have been proposed. Of these, that developed and used extensively by Bird3/, Yancey4/, and Gandrud5/ is considered by the author to be the most satisfactory. It makes use of four interrelated curves (hereafter referred to as be "washability curves"). These curves were explained by Bird in a paper6/ published in 1923, but his explanation has been regarded by some as not sufficiently

Jan 1, 1938

By McHenry Moiser

"SUMMARY This mine, which was discovered in 1846, was active in the 1850's, in the 1870's, and again in 1883. Since this last date, it has been idle. Two parallel bed-veins in lower Silurian limestone, about 50 feet apart, strike N. 70° E. and dip 70° NW. The north vein had an average width of 12 feet to a depth of 50 feet, where it was barren. The south vein had an average width of 16 feet to a depth of 75 feet; on the 110-foot level, although well-defined it carried little or no values. The zinc content of the ore was as high as 12 percent, and some lead and silver were associated with it. A reduction plant for production of spelter and zinc oxide was constructed at the mine. The only available record of production is for 1873 to 1876, inclusive, when 357 tons of smelter was shipped. The mine is caved and inaccessible, and nothing now remains of the treatment plant.Four holes totaling 1,046 feet wore diamond-drilled to probe for extensions of the ore in depth. Core recovery was about 85 percent. No samples were taken for analysis.INTRODUCTION AND ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. The policy of the Bureau is to publish the facts devel¬oped by each project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Branch, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The deposit was examined in 1944 by C. B. White, mining engineer of the Bureau of Minos. Diamond-drilling was under the immediate supervision of McHenry Mosier. 2/ The diamond-drill cores were logged by Arnold Brokaw, geologist, Federal Geological Survey, and 'wore filed in the core library of the Bureau of Mines, Mount Weather, Va."

Jun 1, 1948

By J. S. Walker

The Bureau of Mines monitored surface subsidence and water level fluctuations in 10 shallow observation wells above a series of four adjacent longwall panels in southwestern Pennsylvania, for about 4 yr. This study attempted to correlate the changes in the water levels within the observation wells to the measured vertical and horizontal ground movements associated with subsidence. Results of this study indicate that the fluctuation of the water levels appears to be a function of the well location relative to the mine layout and the proximity of mining. Wells are generally unaffected by mining of a preceding panel unless they are located within the angle of draw for that panel. Wells located at the centerline of a longwall panel exhibit the greatest fluctuation and head loss. This relationship may be related to the strain developed by the advancing longwall face. The water levels in the wells monitored fell at the greatest rate when the ground surrounding the well was in tension. The rate of the decline decreased as the dynamic development of the strains was changing from tension to compression. The water levels were found to be near the premining level before the ground was subject to maximum compressive strain. Nine of the ten wells investigated recovered to their premining water level after mining was completed.

Jan 1, 1988

By R. C. Buehl

An experimental iron blast furnace of 3-foot-diameter hearth, producing about 12 tons of metal per day, was operated for 2 weeks with various proportions of anthracite replacing a corresponding amount of coke. The furnace operated well with anthracite in amounts up to 40 percent of the total fuel and produced metal of uniformly low sulfur and normal silicon contents. An increase to 50 percent anthracite during two attempts resulted in poor operation and the charge hung in the s haft of the furnace. INTRODUCTION Anthracite production in Pennsylvania decreased from 84,400,000 net tons in 1926 to 40,600,000 net tons in 1952, and there was a further decline in 1953 to 30,900,000 net tons. Employment in the anthracite industry dropped from 165,000 men working an average of 244 days per year in 1926 to 57,900 working an average of 163 days per year in 1953,3/ which has naturally resulted in considerable unemployment in the region. The industry is actively engaged in promoting new uses for anthracite to increase the demand and thus improve economic conditions in the region. One possibility is the use of anthracite to replace part of the coke for smelting iron ore in blast furnaces. The tests in this report were made to determine whether this use of anthracite would be feasible.

Jan 1, 1955

By R. D. Ladoo

"At the beginning of 1920 a general feeling of optimism was noted in many talc-producing districts. The industry seems to have recovered from the temporary depression of the first half of 1919 and many mills are running at capacity production with their entire output for 1920 contracted for. The imports of talc for 1919 were only slightly larger than in 1918 by weight and probably no more by value. Thus foreign competition has not begun to be seriously felt. Several new companies in this country have been organized, some to operate new deposits and others to continue the work done by others.An interesting phase of the present situation is the possibility of increased use of talc in paint. There is a shortage of barium sulfate used as,paint filler. Since, for some uses, talc is considered second only to BaSo4 as a filler for paint, it is possible that part of the shortage could be relieved by an increased use of talc.A series of physical tests upon all pigment materials used in the manufacture of paints is being conducted for the Paint Manufacturers Association of the United States. It is important that all types of talc be represented in these tests. Producers of finely ground talc, 200 mesh and finer, are urged to submit samples of at least two pounds each of these grades that are available to paint makers with trade name and quality data, to the Institute of Industrial Research, 19th & B Streets, Washington, D. C., where the tests are being conducted.The Talc Products Company, Inc., Washington Building, Los Angeles, California, has recently been organized to develop a large body of talc one mile north of Riggs, San Bernardino County, California, This deposit contains a compact, white talc which can be sawed into crayons. The company's mill, at Los Angeles) is equipped with a unit of the Raymond system of grinding and air separation, and pencil sawing machines. It is reported that the pencils are being successfully used in Pacific Coast ship yards.The mining of talc where no mill is owned by the operator and the consequent sale of talc in its crude massive state has not proved profitable in a number of cases recently noted. Under exceptional circumstances, where mining costs are low and the product can be sold to a mill near the mine, the operation maybe profitable, but this condition is not common. One mine of this type has recently closed down, at least temporarily; but a second, more fortunately situated, in another district, is continuing operations, although plans are being made to erect a mill in the early spring. Most satisfactory results are ordi¬narily obtained where the mine and mill are owned by the same company.The sale of the Balmat mine of the International Pulp Company, near Gouverneur, N. Y., to J. H. McLear, Gouverneur, and H. G. McLear of New York, has been reported. It is stated that a large part of the property has been already leased to the Sylvia Lake Company, who will operate it. ""Cement, Hill, and Quarry""* states that ""the first mining done on this property was for silver and lead, but it developed into a good zinc producing property and later it was worked for its talc deposits. It has passed through several hands, the American Pulp Co., the Union Talc Co., and the International Pulp Co., all having had it in successive periods since 1891."""

Jan 1, 1920

By M. Howard Berliner

In August 1943 the Bureau of Mines completed seven churn-drill holes in an area of old mine workings near Linden, Wis., formerly known as the Argall mine. The work was undertaken as part of a general investigation by the Bureau of the zinc and lead producing area of southwestern Wisconsin at a time when special effort was being made to increase the production of metals necessary for war. The area was selected for investigation on the basis of its favorable geologic structure, past history, and apparent mineralization.

Jan 1, 1948

By Linneas W. Laage

Coal production from underground coal mines has been important to the development of the industrial economy of the United States. Environmental problems have developed from some abandoned operations. These problems include: mine and refuse pile drainage, subsidence, unsafe mine openings and to a lesser extent mine gases, slope stabilities, mine and refuse pile fires and abandoned equipment and structures. Field investigations in three eastern coal mining districts, two in Ohio and one in Illinois, were performed to document the mine closure procedures used and subsequent problems that developed. The purpose was to identify, evaluate, and rank the seriousness of these problems. Based upon this evaluation, the undesirable present day situations could have been avoided or at least minimized by varying certain mining practices or mine closure procedures. It was found that federal regulations address all of these problems during the pre mining, active mining and post mining phases except for abandoned equipment which is the least threatening problem category. Ideally current practice would prevent future problems. However, the extensive and complicated nature of the legislation, environment and mining practices will necessitate adjustments to the law. The investigator recommends the following: 1) Goal oriented legislation encouraging complete resource extraction, standardization and compilation of mining generated hydrological data, periodic review of the coal mining regulations, and improved communication and cooperation between coal interests, regulators and the public. 2) Permitting effluent limitations to accurately reflect natural conditions. 3) Solidly back filling shafts and individual assessment of sealing or capping requirements. 4) Installing shaft vent pipes into the fill material to intercept and vent methane.

Jan 1, 1982

By Foster Fraas

The electrical conductivity of minerals increases with increase in temperature as a result of the thermal activation of the electrons. Some oxidizable minerals have a change in the stoichiometric proportions after heating in air, and the conductivity does not return to the original value after cooling. Similar changes occur in reducing atmospheres. Other minerals, such as carbonates and hydrates, are completely decomposed. Electrical resistivity measurements on single particles when compared to standard separation measurements show that minerals having resistivities above 1013 ohms respond as nonconductors. Those below 1011 respond as good conductors.

Jan 1, 1956

By S. P. Sandoval

Several researchers have shown that the surface of chalcopyrite becomes hydrophobic under oxidizing conditions. Because dissolution of copper from chalcopyrite in dump leaching occurs under oxidizing conditions, the U.S. Bureau of Mines studied the effect of surfactants on chalcopyrite leaching under dump chemical conditions. Surfactants were selected for study because they can lower interfacial tension. The tests were conducted in shaking water baths using 250-mL Erlenmeyer flasks in statistical experimental design formats. The addition of nonionic surfactants increased copper extraction in the fernc sulfate leaching of chalcopyrite when sufficient Fe3+ was present. A positive interaction between Fe3l+ concentration and surfactant concentration was demonstrated. Copper concentration in the leachhing solutions was increased by as much as 100 pct at 25° and 50° C by adding nonionic surfactants. ionic surfactants decreased leaching. The structure of the nonionic surfactants and their hydrophile-lipophile balance (HLB) influenced surfactant performance. The branched hydrophile of an ethoxypolyol was beneficial to surfactant performance. The ethoxypolyol was the superior surfactant at 25° C, but became unstable at 50° C. Four surfactants, an ethoxyalchohol and three block copolymers, performed best at 50° C.

Jan 1, 1990

By A. W. Fahrenwald

[In studying coarse sand flotation3/ the question of the relation between fineness of grinding and mill capacity logically arose. Everyone familiar with present fine-grinding practice knows that the capacity of a ball mill or similar mill is determined, among other things, by the fineness of the finished product. Undoubtedly a great many mining companies must have a good deal of data directly bearing on this point, yet no quantitative relationship between ball-will capacity and fineness of finished product has been established. The experimental study presented here is an effort to establish this relationship in a semiquantitative way. The subject is a tremendously large one and grows in complexity as the study becomes more searching. In this work the power consumed by the mill in the various experiments was not determined end neither vas the steel consumption measured; mill capacity only was considered.]

Jan 1, 1930

"The following articles were produced through funding under Generic Mineral Technology Center for Respirable Dust research. Full articles appear in the proceedings, 3rd Symposium in the Mineral Industries, published in 1991 by the Society for Mining, Metallurgy and Exploration, Inc.Personal Diesel Exhaust Aerosol SamplerV.A. Marple, K.L. Rubow, and Y. TaoParticle Technology, Mechanical Engineering Department, University of Minnesota, Minneapolis, Minnesota(Section ill. Diesel I: Diesel Particulate Measurement, pp. 73-81)Abstract. Techniques are being developed for measuring the mass concentration of respirable diesel exhaust particles found in underground coal mines. Studies have been conducted over the past five years to investigate size selective 18Dlpling techniques to measure the respirable mass concentrations of diesel exhaust and mine dust aerosol particles in underground coal mines. Results from these studies have been used to develop design and performance criteria for a personal diesel exhaust aerosol sampler.Three personal diesel exhaust aerosol samplers have subsequently been designed and evaluated in both laboratory and field settings. These samplers use size selective classifiers for the determination of respirable mass concentrations of mineral dust and diesel exhaust particles. Their designs are based on the premise that diesel exhaust particles are predominantly less than 0.8 µm while mineral dust is greater than 0.8 µm.One design, selected for field evaluation, consists of a 10 mm nylon respirable dust cyclone followed by a 0.8 µm cutpoint impactor and afterfilter. The cyclone removes the nonrespirable particles while the inertial impactor state, collects the mineral dust on an impaction plate and allows the diesel particles to penetrate to an afterfilter. The two sample fractions of the respirable particles ( <0.8 µ.m and >0.8 µm) are gravimetrically analyzed to determine the concentrations of the diesel and mineral dust portions in the respirable coal mine aerosol."

Mar 1, 1992

By F. J. Gallagher

Some serious fires have occurred in bituminous-coal mines because of short circuits on direct-current power systems that do not have adequate circuit-breaker protection. The writer&apos;s observation of circuit-breaker installations in numerous coal mines leads to the conclusion that many persons am not properly informed as to the true functions, limitations, and operation of circuit breakers. Faulty protection results in fire hazards that endanger lives and property. Proper circuit-breaker protection would greatly minimize or, in many instances, eliminate the hazards; moreover, many operating advantages of proper application of modern circuit breakers would be gained. The purpose of this circular is to show why fire hazards exist in many mines despite the use of circuit breakers and how, the hazards may be overcome. A method is given for determining whether additional circuit-breaker, protection is required for a specific 250/275-volt direct-current distribution system, and, if so, the approximate locations and capacities of the required supplemental breakers.

Jan 1, 1951

By S. J. Broderick

[The authors gratefully acknowledge the assistance of O. C. Ralston, chief engineer, Nonmetals Division, Bureau of Mines, Who suggested the problem and Gave valuable aid during the course of the work. Thanks axe due also to Will H. Coghill, supervising engineer of the Southern Experiment Station, Bureau of Mines. INTRODUCTION One phase of the general program for utilization of coal-mine waste led to the possibility of making a water softener from the material, as the waste matter contained both coal and clay and. it is known that both these substances can be so activated as to exhibit distinct base-exchange properties. The carbonaceous]

Jan 1, 1941

By A. W. Newberry

The Virginia copper district is situated in North Carolina and Virginia. It contains many mines and prospects that were active at the turn of the nineteenth century. The Bureau of Mines, as part of the strategic-minerals program, began a project in September 1942 to investigate and explore the most promising of the mines in the district. The Seaboard, High Hill, Durgy, and Blue Wing mines were the sites of the main project activity. This report deals principally with these four mines. Drilling did not discover any new ore shoots but indicated the persistence of known ore shoots in depth. There appears to be no indication of impoverishment of copper with depth.

Jan 1, 1948

By H. L. Riley

This report describes the methods and equipment used by the Watauga Stone Co. to drill and blast limestone in a two-level quarry, and to crush, screen, blend, and load this stone. Power requirements per ton of stone produced are reported. The personnel requirements for individual phases of the operation are tabulated in man-hours per ton of stone produced.

Jan 1, 1963