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By B. J. Scheiner

Extraction of silver from silver mill tailings by an electrolytic oxidation procedure was investigated by the Bureau of Mines. Various parameters affecting silver extraction, such as electrolysis time, particle size, and dissolution of the silver as the tetrachloro or cyanide complex, were studied at 30° C with an electrolyte concentration of 20 weight-percent sodium chloride. Resulting silver extractions ranged from 77 to 90 percent, depending on the tailings being treated. Concomitant extraction of mercury ranged between 90 and 95 percent. Power consumption was 52 to 90 kilowatt-hours per ton for the tailings investigated. Comparative experiments using direct cyanidation resulted in extraction of 46 to 82 percent of the silver and 20 percent of the mercury. Cyanide consumption ranged from 3.3 to 9.4 pounds per ton of tailings, depending on the tailings being treated. Silver and mercury were recovered from leach solutions by precipitation on iron powder, followed by conventional distillation and fire refining steps.

Jan 1, 1972

By M. H. Stanczyk

The Bureau of Mines made bench-scale laboratory tests on a sample of typical Florida phosphate slime to determine alumina and phosphate extractions obtainable by agitation leaching, by baking and curing, and by a leach-electrolysis scheme. Recovery of mineral values from leached slime pulps by resin-in-pulp ion exchange contact and the reaction of the leached pulps to filtration, flocculation, and settling were also investigated. The best extractions of alumina and phosphate were obtained by (l) agitation leaching with sulfuric, hydrochloric, or nitric acid at an elevated temperature or (2) curing or baking the slime with sulfuric acid. Alumina extractions ranged from 80.8 to 90.0 percent and phosphate extractions ranged from 93.3 to 98.4 percent when the slime was leached at 90° C with sulfuric, hydrochloric, or nitric acids. Baking the slime with sulfuric acid at 200° C for 4 hours yielded an alumina extraction of 92.3 percent and a phosphate extraction of 97.0 percent, whereas curing with sulfuric acid at 100° C for 24 hours gave slightly higher alumina and phosphate extractions. Flocculation and settling properties of the slime were virtually unaffected in all cases. Filter area requirements, although somewhat improved as compared to untreated slime, remained relatively high. The lowest filter area requirement obtained was 44 square feet per ton of dry solids treated per day. Contacting leached slime pulps with ion exchange resins depleted the leach pulps of solubilized values; however, the filtration and settling properties of the barren pulps were unaffected. A leach-electrolysis scheme resulted in some concentration of solubilized phosphorus, but the method showed little promise of being commercially feasible.

Jan 1, 1966

By John Dixon

This paper is one of a series on milling methods and costs being published by the Bureau of Mines. Acknowledgment is made to J. B. Tyrrell, managing director, and Wm. Sixt, manager of the Kirkland Lake Gold Mines, for permission to publish this article. The Kirkland Lake Geld Mining Co.'s mill is located on Government Road at the west end of the productive part of the Kirkland Lake mining area, 1 mile west of the village of Kirkland Lake. The crushing plant is connected to the shaft house of No. 2 shaft, which is now the only operating shaft.

Jan 1, 1931

By William C. McLaughlin

In the deep vein mines of the Coeur d'Alene mining district, rock bursts are a potential hazard to the mine structure and underground personnel. Damage repair costs are estimated by one company to exceed $1 per ton of ore mined. The Bureau of Mines, in cooperation with the mining companies, has conducted research intermittently over the past 10 years to help reduce bursts. Onsite inspections of major rock bursts were conducted, and reports were submitted to mine management; these included the geology and geometry of the affected area. The paper discusses the development and improvement of microseismic and surface monitoring equipment. The underground microseismic network, when operated on a regular basis and the results plotted daily, is capable of detecting stress concentration in certain areas. The surface seismographs record rock bursts, blasts, earthquakes, etc., throughout the district and show approximate location, time, and relative intensity of the event.

Jan 1, 1976

By Thomas C. Atchison

The experimental work described in this report is part of a continuing study by the Federal Bureau of Mines of the fundamental physical processes involved in breaking rock with explosives. Six explosives were tested for their strain-producing abilities in a dolomitic marble. The explosives selected for testing had a tenfold variation in detonation pressure and a fivefold variation in characteristic impedance (product of loading density and rate of detonation). Strain pulses produced by the detonation of small charges of the explosives were recorded at distances of 5 to 130 feet. Peak strain, ?, was found to decrease with distance, R, in accordance with an exponential propagation law previously determined for other rock types, namely ? = (K/R)e ?aR The absorption constant, a, did not vary significantly with the explosive and was of the same order of magnitude as that for other rock types. The different explosives produced a fivefold variation in the value of the intercept constant, K.

Jan 1, 1961

By C. A. Herbert

In summer, when hot, moisture-laden air enters a coal mine in the region east of the Mississippi River, the moisture is likely to condense on the roof and ribs because the incoming air is cooled below its dew point upon contact with the roof, ribs, and floor of the mine passageways. When the roof and ribs become wet owing to this condensation they are said to "sweat." In many mines, as soon as this sweating begins, shale or slate roof that appears solid and strong in winter begins to cut and fall. For a long time most mining men believed (many still believe) that the roof trouble was due to this sweating. However, from observation of conditions in one mine the operators concluded that the trouble was caused by expansion and contraction of the roof due to changes of temperature. This opinion was confirmed by experiments at several mines in cooling the air as it entered the mines. Methods used in these mines for cooling the air are described in this circular. MINE A At mine A the roof gave considerable trouble in the summer, and it was observed that where a spray of water from a leaking dam kept the roof wet and at a uniform temperature no difficulty was experienced with the roof, although it had cut and fallen on either side of that point. From this fact the company officials concluded that changes of temperature in the air rather than moisture caused the trouble and that if the incoming air were cooled to approximately normal strata temperature much of the additional roof trouble experienced during the summer would be overcome.

Jan 1, 1940

By A. Wahab Khair, Nagendra P. Reddy

"This paper presents an analysis of preliminary tests on the effect of in-situ and operating parameters on fragmentation of coal using a specially designed unique automated rotary coal cutting simulator (ARCCS). In these tests coal blocks with an approximate dimension of 18 in. x 15 in. x 6 in. (45.7 cm x 38.l cm x 15.2 cm) were first. subjected to confining pressures, equivalent to in-situ conditions. Such. blocks were then cut by the cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using an optical microscope with a camera attached to it. Furthermore, the coal fragments were collected in bags using a vacuum cleaner. These fragments were then sieved for size distribution analysis. The results of the preliminary tests indicated that underground coal cutting can be simulated in the laboratory and the effects of the important parameters, i.e. operating and in-situ parameters, can be studied successfully. INTRODUCTIONThe continuous-mining machines which were introduced in the 1950's now account for more than half the production of coal from underground mines. Unfortunately, these continuous miners, which were designed for increased productivity, have also increased the concentration of respirable dust in mines. As a result, the Federal Coal Mine Health and Safety Act of 1969 was enacted to enforce on the coal operators that the airborne respirable dust not exceed 2 mg/m3, and was intended to reduce the incidence of coal workers pneumoconiosis. This plus the other aspects of the legislation and the subsequent monitoring and enforcement by MSHA made it very imperative that the coal operators provide a relatively healthier and safer working environment for the coal miners. Since 1970, the Federal government has paid over 11.7 billion dollars to more than 470,000 miners with coal workers pneumoconiosis and their survivors (1). These regulations, coupled with the assessment of the continuing burden on miners, the mining industry and taxpayers appear to have provided an impetus for the mining .community towards comprehending the different parameters that influence dust generation and entrainment."

Jun 1, 1988

By Fred N. Kissell

Air recirculation caused by dust scrubbers at coal mine working faces was examined by the Federal Bureau of Mines with regard to the potential hazards caused by a possible buildup of methane gas. A theoretical analysis indicated that there was no apriori way to predict the effect of scrubber recirculation on methane concentration levels. Experiments conducted in a full-scale model of a working face area indicated that methane levels were dependent to a great extent on the location of the scrubber exhaust, but that the scrubber recirculation did not substantially increase the methane concentration above those levels that would have prevailed were the scrubber not in operation. An analysis of two underground scrubber trials showed that the scrubbers had no significant effect on methane levels, and a review of explosions attributed to recirculation showed that these were characterized by a lack of fresh air as well as recirculation. It was concluded that high methane levels are due more to a lack of fresh air than to recirculation.

Jan 1, 1975

By John R. Duda

The Bureau of Mines is developing estimates of capital investment, operating cost, and selling price for underground mines producing bituminous coal by various mining methods. This study estimates the required capital investment, operating costs, and selling prices for two hypothetical mines designed to produce 1.5 and 3 million tons per year (MM tpy)3 by using a longwall system in conjunction with a continuous-mining system. The coal properties being mined are assumed capable of sustaining a 20-year product Lon period. Wages and union welfare payments used in this study are those in effect as of December 6, 1975, as set forth under the National Bituminous Coal Wage Agreement of 1974. Costs of materials and equipment are based on January 1976 Indexes. Initial capital investment is $33.8 million for the 1.5-MM-tpy mine and $61 million for the 3-MM-tpy mine. Capital requirements, including deferred investments, were estimated to be $52.5 and $94.2 million, respectively. These figures translate into total capital investments of $34.87 and $31.31 per ton of annual production. Assuming a desired 15-percent discounted cash flow rate of return, with Federal income taxes at 50 percent, the required selling prices would be $12.06 and $10.94 per ton for the 1.5- and 3-MM-tpy mines.

Jan 1, 1976

By A. T. Harris

Ground quartzite, known in the industry as amorphous silica, is produced from a quartzite deposit near Honey Brook, Pa., by George F. Pettinos, Inc., of Bala-Cynwyd, Pa. The quartzite is mined by the open pit method and processed in a mill at the mine. The operation regularly produces five standard grades of sand and one grade of crushed stone; however, the company accepts special orders and will produce material to meet the customer's specifications. Beneficiation (chiefly crushing and screening) is controlled by laboratory screen tests on samples taken during preparation of the sand. The chief uses of the sand are for foundry operations, furnace lining, concrete aggregate, and other specialized uses. The quartzite in this deposit is of uniform composition and does not require control by chemical analysis. However, for special purposes, analysis will be furnished.

Jan 1, 1965

By L. A. Neumeier

The Bureau of Mines evaluated the properties of a Zn-0.75 pct Cu-0.12 pct Ti alloy extruded at temperatures between 400° and 720° F. The extrusions were made with a reduction ratio of 28-to-l and at relatively slow speed. Rod was also extruded at 560° and 640° F with a reduction of 255-to-l. With increased extrusion, temperature, extrusion pressures decreased substantially and creep resistance of the rod improved significantly. Coefficients of thermal expansion were low in the long rod dimension. Microstructures, hardness, and tensile properties were also evaluated, and a limited evaluation was made of bend ductility at 32° F for the rod extruded with the 255-to-1 reduction.

Jan 1, 1969

By R. E. Heithecker, Van A. Mills

"Crude oils are capable of dissolving quantities of gas under pressure. This fact has been known for some time, but questions have arisen as to the effects of gas in solution upon the characteristics of the oil. Previous investigations4 show that gas in solution in an oil affects the viscosity and surface tension of the oil, but the effects on the volume and A. P. I. gravity of the oil have not been known. The results given in this report show that there is a decided change both in volume and in the A. P. I. gravity of the oil due to the solution of the gas in the oil under pressure. As gas is dissolved, the volume of the oil and the A. P. I. gravity increase. The converse of this phenomenon is also true: if the gas is released from a saturated oil, there is a shrinkage in volume and a decrease in A.P.I. gravity due to the release of gas from solution. However, various oils show marked tendencies to retain a portion of the dissolved gas upon releasing the pressure to that of the atmosphere. This retained gas has an appreciable effect on the volume and A. P. I. gravity of the oil because the oil does not resume its initial volume or gravity while it retains dissolved gas. In a sense the oil has been ""freshened"" and will not return to its original or weathered volume until it loses some of the lighter fractions. Wiggins5 has shown that a fresh oil decreases both in volume and in gravity because of the weathering of the lighter fractions while the oil is standing in storage tanks.This paper includes data attained during the determination of volume and gravity correction factors to be applied in the oil recovery investigations of the Bureau of Mines. Three oils having a wide range in gravity were used in determining the correction factors. These oils were from the Bartlesville-Dewey field, Oklahoma, the Seminole field, Oklahoma, and the Inglewood field, California. The same gas that was used in the oil recovery experiments was used throughout this investigation. Determinations were made of the volume and A.P.I. gravity increases resulting from the gas going into solution at 200, 400, 600, 800, and 1,000 pounds pressure; also the increases in the volume and gravity of the oil due to retained gas were determined after the dissolved gas was liberated from solution by releasing the pressure to that of the atmosphere.Samples of residual and liberated gas were taken throughout the investigation in order to study the selective absorption and selective retention by the oil of the various constituents of the gas. The analyses of these gas samples showed that there was selective absorption and selective retention of the constituents of the gas. The tests on Inglewood crude gave the most pronounced example of selective absorption and selective retention of the gas.All of the tests were conducted at a constant temperature of 709F."

Oct 1, 1928

By T. L. Joseph

The size and accessibility of the Minnesota manganiferous iron ore deposits make them attractive as a potential source of ferromanganese, which is essential in the production of steel. For several years the Bureau of Mines has been conducting experiments to determine the feasibility of producing ferromanganese from these ores by a three-step process which involves (1) the smelting of the ores in the blast furnace to produce a high-phosphorus spiegel; (2) the treatment of the spiegel produced from step 1 in an electric or open-hearth furnace to separate the manganese from the phosphorus and the iron; and 3) the smelting of the high-manganese slag from step 2 to produce ferromanganese. The details of the first two steps of the process and the results of tests with the experimental furnaces have been given in previous reports.

Jan 1, 1931

By H. W. St. Clair

In about 1930, Degussa applied for a patent on a process for the of oxides, carbides, sulfides, and other nonmetallic impurities by filtration in the molter state. The filtering media listed were wire screen, coke, and ceramic materials, and quartz. It was also suggested that filtration might be combined with chemical reaction between the metal and the filter medium or that might be added to the system. No patent was granted on the general scheme, but several years later a patent was granted on a continuous process purification of crude light metals, especially or alkali earth and their alloys. The melt was stirred at 1 temperature at which the impurities (such as oxides and salts) remained solid and the metal was drawn through a filter tube. The impurities collected under the filter and were removed by a screw conveyor. Crude sodium was purified by this process in Degussa's Knapsack plant. During the last war, when the refining of scrap became a very urgent Problem in Germany, experimental investigations were extended to separation of other metals and metallic compounds by filtration. Preliminary experiments seemed to confirm the opinion of Dr. L. Weiss that the principles of wet chemical filtration might be applied to a great extent in the purification of metal and alloys.

Jan 1, 1949

By H. D. Baylor

This is the first of a series of papers describing mining methods and costs at cement plant quarries throughout the United States and deals directly with those methods employed and costs obtained at the quarry of the Louisville Cement Co. located at Speed, Ind. ACKNOWLEDGMENTS The author wishes to acknowledge the assistance of Mr. J. M. Buohheit, superintendent of quarries, and Mr. H. E. Schoonover, quarry engineer, in furnishing data and in compiling this report.

Jan 1, 1930

By P. C. Good

This Bureau of Mines report describes the preparation of phosphoric acid directly from phosphate ore, without prior beneficiation, in a small-scale, continuous process research unit, as part of an effort to improve minerals and metals recovery from domestic resources while minimizing environmental effects. Three phosphate-matrix samples, ranging in grade from 18.2 pct P20S5to 11.9 pct P205, were dry-fed at a rate of 1.82 kg/hr (4 lb/hr) to a continuous-circuit, 12-liter, single-tank digester to yield phosphoric acid and byproduct gypsum filter cake. Comparison with earlier data shows that a significantly improved filtration rate was attained in a single-tank reactor compared with that attained in a five-tank reactor train processing the same ore. Iron and aluminum impurities in the product phosphoric acid averaged about 60 pct higher than amounts reported in commercially prepared, concentrate-derived acid. All gypsum filter cakes prepared had a firm, sandy texture, rendering them physically suitable for stacking or landfill use. Introduction of dry attritioning and air classification approximately doubled the attainable filtration rate when the dry-beneficiated product was digested. In air classification, there was a 12-to 14-pct P205 loss. Depending on the technique used and the matrix grade, overall P205 recovery ranged from about 72 to 89 pct.

Jan 1, 1979

By Charles E. Munroe

At the outset of the war the uncontrolled production and possession of explosives obviously became a serious menace to the safety of persons and property and the successful conduct of military opera- tions. Even in the years immediately preceding the entrance of the United States into the Great War explosives were employed in attempts to wreck munitions plants as at Eddystone, Pa., or to inter- rupt transportation and conveyance by demolition of munition-laden cars as at Black Tom Island, N. Y., or by attacks on ships, bridges, and viaducts. Outrages with explosives, such as that which Holt inflicted on the Senate reception room, United States Capitol, were not infrequent, and often caused serious loss of life and injury to persons as well as destruction of property. The regular manufacturers of explosives were keenly alive to this menace and early took such steps as lay within their power to meet it as is shown by the following letter:

Jan 1, 1921

By J. H. McClain

In the last 3 years' operation of the zirconium-production plant, zirconium metal has been employed to good advantage in many applications. The most frequent use has been in situations requiring resistance to attack by hydrochloric acid. In this service, it has been shown to be a serious competitor to Hastelloy. Zirconium also has excellent resistance to most other corrosives end could be considered for use as an all purpose metal. For example, this report cites 18 applications in hydrochloric acid, 4 applications in sulfuric acid, 5 applications in phthalic-hydrochloric acid, 3 applications in wet hydrogen chloride-chlorine atmospheres, and 2 applications in fused caustic.

Jan 1, 1954

By J. W. Eckerd, W. S. Sanner, P. L. Woolf, R. E. McKeever

The Bureau of Mines experimental blast furnace was operated successfully with anthracite metallurgical briquets . Tuyère pressures were higher and more erratic than for operations using coke , and furnace " hangs " occurred more frequently . Higher hot - blast temperatures were required to maintain the quality of the metal . By using higher hot blast temperatures , the fuel and production rates and slag volumes were comparable to those obtained for all - coke operation . The anthracite metallurgical briquets exhibited excellent mechanical strength and descended through the shaft of the furnace with little breakage or reduction in size .

Jan 1, 1964

By H. R. Hardy Jr., E. J. Kimble Jr., H. W. Shen

"The primary objective of this research project is to study the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. Secondary objectives include the investigation of the acoustic emission technique as an indirect method for coal dust characterization and remote bit wear monitoring. The results of the project will be useful in developing efficient coal cutting techniques which significantly reduce the harmful coal dust components, and in providing methods for remote monitoring of bit condition and associated coal dust character. This paper will outline recent experiments carried out on coal under uniaxial compression, linear single-bit cutting, and cutting using a laboratory-scale, single-bit shearer. During the experiments acoustic emission and a variety of other mechanical parameters were monitored. · A commercially available artificial intelligence computer package, namely: JCEPAK (Intelligent Classifier Engineering Package), has been utilized to provide a powerful and objective means for AE waveform analysis. This program is able to evaluate a number of features of each AE event and to make objective comparisons between AE signals associated with different loading or cutting parameters. Finally, the paper will discuss the results obtained from a variety of coal breakage tests.INTRODUCTIONStudies to date clearly indicate that the reduction of the severity, and eventual elimination, of Coal Workers' Pneumoconiosis (CWP) depends on gaining fundamental understanding in a number of major areas. These include dust generation and entrainment, transportation, suppression, medical effects of dust and possible treatment. At present a project is underway by the authors to investigate the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. An important aspect of this on-going project is the development of acoustic emission (AE) criteria which will make it possible to carry out remote monitoring of coal cutting operations. Suitable on-line analysis of monitored AE data would allow engineers to evaluate factors such as shearer bit condition and cutting efficiency, and to quantify the particle size and shape distribution of the generated dust. The on-going AE studies are fundamental in form and were undertaken to evaluate the general feasibility of AE monitoring techniques using simplified coal cutting procedures. This paper will outline recent experiments on coal under uniaxial compression, linear single-bit cutting, and cutting using a laboratory-scale, single-bit shearer. Additional information on these studies are presented elsewhere [4]."

Dec 1, 1996