Search Documents

By H. J. Heinen

This Bureau of Mines report reviews the recent developments in the heap leaching of gold ores with dilute cyanide solutions and the recovery of gold and associated silver from the pregnant effluents by a carbon adsorption-desorption method. Mineralogical considerations, experimental work, field studies, and commercial operations are described. Also presented are recent process advances developed by the Bureau, including the application of (1) alcohol additives to the conventional hot alkaline cyanide strip solution to enhance gold desorption from precious metal-laden activated carbon, and (2) Na2S precipitation of the silver from geld-silver cyanide solutions as a means of reducing the inventory of carbon required for precious-metal adsorption from heap leach effluents and for the production of low-silver bullion from activated carbon stripping solutions.

Jan 1, 1978

By C. F. McCarroll

The effectiveness of an industry's safety activities can be gaged best by the accident records of that industry. In an effort to gage conditions in the petroleum industry, and with the objective of helping to reduce the number of accidents in it, the Bureau of Mines from time to time has tabulated, analyzed, and published pertinent statistical information.3/. These reports have dealt with distribution, causes, and costs and related phases of accidents for various and collective divisions of the petroleum industry in several sections of the country. This type of study aids the personnel of the Bureau in planning the course of its activities in accident-prevention work and gives useful data to persons engaged or interested in the promotion of safety in the petroleum industry, which will aid them in their efforts to reduce the number and severity of accidents. A majority of petroleum operators and "service? contractors have acknowledged their responsibility to provide their employees with safe working conditions and to their stockholders for greater economic value of invested capital by establishing safety divisions within their respective organizations. Such divisions have a primary duty, namely, to see that properly designed and guarded machinery and working equipment are furnished the employees and that they are trained in the safest practical methods of performing their work. Some companies and individual operators, however, have shown little or

Jan 1, 1939

By Mark I. Copeland

The Bureau of Mines investigated the effect of up to 1 wt-pct of copper and silicon on the heat treatment response and hardness, tensile, and impact properties of hot-rolled medium-carbon steels. The steels were prepared by induction melting and fabricated into plates by forging and rolling. The tensile strength of 0.2-wt-pct carbon steels containing 0.3 wt-pct silicon was affected significantly by copper in both the hot-rolled and heat-treated (600° C) conditions, whereas the tensile strength of the 0.3-wt-pct carbon steels was less affected. A 600° C treatment was considered optimum as a post-rolling treatment to strengthen the steels by copper precipitation. Strengthening of 0.2-wt-pct carbon steels by silicon was reduced by increasing copper contents.. Optimum impact strengths occurred at about 0.3 wt-pct silicon in 0.2-wt-pct carbon steels containing 0.6 and 0.8 wt-pct copper. The impact strengths were lowest for 0.2-wt-pct carbon steels containing over 0.8 wt-pct copper and greater than 0.3 wt-pct silicon, especially in the heat-treated condition. Copper and silicon solutes and copper precipitates strengthened the steels. This effect was augmented slightly by strengthening through grain refinement by these solutes.

Jan 1, 1973

By Donald E. Ralston

The Huntsville study area in northeastern Alabama consists of Jackson, Limestone, Madison, and Marshall Counties. Major emphasis was placed on the Huntsville urban area in Madison County to analyze the relationship of urban growth and the minerals industry. Huntsville was delineated into its component urban, suburban, and rural parts for 1964, and the primary area of growth was predicted for 1990. Population estimates were made for the four-county area as a unit and Madison County separately, and projected to 1990. Demand estimates for crushed stone and sand and gravel were made for the same area units and projected to 1990. Analysis of quarry sites in the Huntsville area was made for the present and for the future. The mineral operations of the study area are all located in rural areas; in the case of Huntsville, the mineral sites are located in areas defined as "rural" in the component urban-suburban-rural system. The operations outside Madison County can expect to have minor problems with urban encroachment, while those operations in Madison County can expect major problems associated with urban growth and development. Some of the problems associated with limes tone production can be reduced if producers invest in capital equipment that will reduce the nuisances inherent in this activity. Although urban expansion endangers some quarry operations in Huntsville, topographic and political restrictions which prevent urban expansion can effectively shield quarry operations for some time.

Jan 1, 1970

By P. T. Brooks

Mineral nodules from the ocean floor represent a vast potential source of manganese, nickel, cobalt, and copper. Process development studies to devise methods for recovering these metals were conducted by the Bureau of Mines using two types of nodules--relatively low-grade calcareous nodules from the Atlantic Ocean and higher grade siliceous nodules from the Pacific Ocean. Ammoniacal carbonate leaching of reduced nodules appeared to have the best potential for processing the calcareous nodules, but the method proved to be impractical for recovering manganese. Extraction of 90 percent or better of the nickel, cobalt, and copper showed the technique to be attractive for recovery of these metals. The siliceous nodules appeared amenable to a process that starts with either a sulfur dioxide leach or a sulfation roast followed by a water leach to dissolve the soluble sulfates.

Jan 1, 1971

By W. L. Falke

The Bureau of Mines has developed a system that permits the "soft" soldering of aluminum and aluminum alloys with standard tin-lead solders. The method employs application of a thin nickel-copper-alloy coating to the substrate, which enables the tin-lead solders to wet readily and spread over the areas to be joined. With conventional technology, aluminum and aluminum alloys are extremely difficult to solder because tenacious surface oxide films prevent wetting. With the Bureau-developed method, the aluminum substrate is mechanically or chemically cleaned to facilitate bonding to a minute layer of zinc that is subsequently applied with an electroless zincate solution. The nickel-copper-alloy (30 to 70 pct Ni) coating is then applied electrolytically over the zinc, using immersion cell or brush-coating techniques. Development of acetate electrolytes has permitted deposition of the proper alloy coatings. The coated areas can then be readily joined with conventional tin-lead solders and fluxes. The joints so formed are ductile, strong, and relatively corrosion resistant, and exhibit strengths equivalent to those formed on copper and brass when the same solders and fluxes are used. The method has also been employed to soft-solder magnesium alloys.

Jan 1, 1983

By L. V. Clark, Arthur La Motte

"INTRODUCTION The U. S. Bureau of Mines in 1930 and 1931 made a study of the properties and characteristics of liquid-oxygen explosives (L.O.X.) at the request of one of the largest users, in order to determine and eliminate the hazards attending its use.This report deals with the examination of absorbents for L.O.X. to (1) determine their most desirable and most undesirable characteristics, (2) to find ways and means of desensitizing absorbents to mechanical shock, and (3) to determine the effect that such desensitization of absorbents has on the explosive Characteristics of L.O.X.ABSORBENT MATERIALS The absorbent used in driving the Simplon Tunnel, the earliest project in which L.O.X. was used, was composed of crude petroleum, soot, and kieselguhr. During the World War, powdered cork, soot, sawdust, powdered straw, or other similar powdered materials were mentioned in the German military instructions for use of ""liquid air"" explosives. At that time the common types of absorbent, materials were compounded ones containing the above ingredients as well as kieselguhr, paraffin, gas oils, charcoal, bituminous coal, etc.Kuryla and Clevenger4 investigated absorbents of the above type and made the following statement concerning them:"

Apr 1, 1932

By D. E. Kirby

The electrochemical reduction of AlC13 was investigated as a process for the production of aluminum. An externally heated, single-compartment cell with a rammed refractory lining was used with molten KCl-NaCl-AlC13 electrolyte. Aluminum was deposited qt 700° to 760° C with a current of 100 to 200 amperes on a molten aluminum cathode. Chlorine was evolved at a graphite anode and collected and measured to provide a quantitative evaluation of the AlC13 reduction. Aluminum was removed from the cell by siphoning or ladling. Granular AlC13 was added periodically to replenish that depleted from the electrolyte. Concentrations of 7.5 to 17.5 percent AlC13 in the electrolyte were optimum for operation. Anode current efficiencies of 83 to 85 percent were attained, using anode current densities of 5.9 amperes per square inch and an anode-cathode distance of 4 inches. The chemically bonded, alumina liner was resistant to attack by aluminum and chlorine but susceptible to erosion at the surface of the electrolyte. Titanium diboride proved suitable for the electrical connection to the molten aluminum cathode. Aluminum of a purity equal to or better than 1100 series metal was electrowon continuously from commercial AlC13 for a period of 4-1/2 months.

Jan 1, 1970

By S. J. Haynes

"This paper documents the characteristics of the different quartz veins, and their relation to gold, in the turbiditic Meguma domain of eastern Nova Scotia. Eleven different types have been distinguished in the greenschist facies on the basis of form, internal structure, mineralogy, wallrock alteration and crosscutting relationships to each other and to regional structures. Gold is present as rare visible disseminations in host rock slates and in ore-grade, early-formed veins, that pre-date the formation of upright Acadian folds and intrusions of Devonian granitoids. Four vein types pre-date Acadian folding. Five gold-deficient vein types are associated with Acadian folding (syndeformation); whereas two gold-deficient vein types clearly post-date this deformational event: Previously unreported, wall rock alteration is associated with early crosscutting and semiconcordant auriferous veins. In contrast, early stratiform veins are devoid of wallrock alteration. It is suggested that the auriferous vein arrays formed as submarine exhalitive systems over synsedimentary tensional faults and that the Meguma domain may represent the opening of a basin similar to the modernGuaymas rift .IntroductionThe term ""turbidite-hosted gold deposits"" is introduced to distinguish gold deposits contained within a turbiditic sequence of wackes and shales (or their metamorphosed equivalents) from gold deposits in other types of sediments. Usage and justification for the term is similar to ""carbonate-hosted lead-zinc deposits"" or ""volcanogenic massive sulphides"". A range of different characteristics can be present in individual deposits, some of which may be indicative of specific deposit types in the same manner that volcanogenic massive sulphides can be subdivided into ""Cyprus type"", ""Kuroko type"", ""Besshi type"", etc. Historically, gold deposits hosted by turbiditic flysch were an important class of quartz-vein gold mines in the 19th century. They included the goldfields of Victoria, Australia, Otago, New Zealand and Nova Scotia, Canada. Production from most of these fields had ceased by World War II and interest in this type of deposit waned. However, the recent exploration interest in gold has resulted in both re-assessment of the classical mining camps and the discovery that ""turbidite-hosted"" gold deposits are present in many parts of the world.Mapping of the regional geology and gold deposits of the Megumadomain of Nova Scotia was carried out by E.R. Faribault of the Geological Survey of Canada between 1886 and 1939. Faribault produced a comprehensive series of maps and reports for each gold district, a compendium of which was published by Malcolm (1929)."

Jan 1, 1987

By George J. Conroy

To provide data as a basis for proposed acceptance standards and procedures covering permanent splices in trailing cables, the Bureau of Mines conducted testing programs on the flexure life in flat types W and G dc trailing cable splices and ground conductors. Primary reliance was placed on laboratory testing, although some cross comparisons were made at manufacturers' plants and mine operations Besides providing data for acceptance standards and procedures, results of the program should promote the general improvement of commercially available splice kits.

Jan 1, 1977

By Russell E. Griffen

With the development of larger mine-haulage trucks in recent years, the visual field of the driver has diminished correspondingly. Specifically, the operator's lack of direct vision in the right front area and directly to the rear constitutes a serious hazard to personnel in nearby small utility vehicles. Recently developed electronic technology has made it possible to supplement the use of mirrors and fresnel lenses to warn the operator of specific collision dangers in the truck's blind areas. This Bureau of Mines report describes the results of a coordinated contract and in-house research program to develop and test in-mine prototype electronic systems to detect the presence of smaller vehicles within the blind areas of large mine-haulage trucks. Each system utilized transmitters installed on the smaller vehicles and receivers installed on the haulage trucks. Transmitting techniques tested included both low-and high-frequency radio waves. On-vehicle testing established the engineering feasibility of each approach. Further private sector product development to improve reliability and reduce system costs is recommended. Mining companies should consider the advantages of each type of system.

Jan 1, 1988

By W. H. Tomlinson

This publication presents the basic text for a 20-hour accident-prevention training course developed for supervisors by the Federal Bureau of Mines. During the past 2 years, the course has been used by the Bureau in teaching more than 300 groups of coal-mine supervisors-men whose responsibility is twofold: To manage in production and maintenance phases of coal mining and to guide their men along paths of safety. This is a handbook for teaching teachers. In this handbook will be found references to safety practices followed by companies that consistently have low accident records. These companies credit their outstanding performance to the adoption and faithful observance of accident prevention by supervisors and workers alike on a wholesome, cooperative basis. Teaching safety to workers involves both on-the-job and classroom-type instruction. If such training is to be permanently effective, it must be reinforced consistently on the job by the immediate supervisor of the worker. This publication is intended to provide such a supervisor with the motivation to provide such follow-up and shows how he can accomplish it effectively.

Jan 1, 1962

By M. Hertzberg

Results of a comprehensive study of the absolute spectral radiance of the infrared emissions from methane-air explosions are reported. The spectral growth of these expanding flames were recorded with a time resolution of 1 msec in the spectral range of 1.7 to 5.0 µm. Time-resolved spectra were obtained for methane-air mixtures as a function of stoichiometry, nitrogen dilution, and Halon dilution, in a 9-liter vessel under different venting conditions. Data are also presented for coal dust-air explosions. Temperatures, obtained from the absolute radiances and from a band ratio technique for methane-air, are internally consistent and are generally 50° to 200°K below adiabatic flame temperatures. All near limit mixtures gave essentially the same flame temperatures (1,500° to 1,600° K) regardless of whether the limit was obtained by dilution with excess air, excess methane, excess nitrogen, or Halon. The coal dust explosion spectrum is essentially a blackbody continuum at 1,500° K with some selective emission at 4.4 µm from hotter CO2. The data are analyzed in terms of the radiative dynamics of a sperically expanding flame zone. The importance of radiative transport is assessed. An equation is derived which relates the instantaneous fraction of combustion power radiated to adiabatic variables.

Jan 1, 1973

By D. R. Corson

The Bureau of Mines instrumented an operating stope in a deep vein mine to determine the amount of wall closure and the magnitude of loads imposed on a backfilled stope. Hydraulic pressure cells used to monitor pressures in the fill) with bolt closure points to measure vein-wall movement and the procedure for their installation) are described) and the results of the laboratory calibration analysis of the reliability of these cells are given. An attempt to monitor density and moisture changes in the backfill with a nuclear density-moisture device was only partly successful) owing to either deformation of access tubing or relative displacements of the vertical vein walls relative to the emplaced tubes. Data from the instrumentation indicate vein-wall closure in excess of 20 inches and pressures within the fill approaching 600 psi. Analysis) incorporating field data with results of laboratory tests of the compressibility of timber and tests defining the constrained moduli of the fill) points out the limited restraint to vein closure offered by timber sets. Ground movement induced by mining activity could be more effectively con-trolled by the use of densely compacted backfill.

Jan 1, 1967

By Tom Tallone

In the majority of metal and nonmetal mining operations, narrow vein deposits are being mined with slusher hoists. Thin; method of mucking is costly, due in part to its inherent labor intense operation and to its inability to muck 100 pct of the deposits. Mechanized equipment would greatly improve the material handling in narrow vein mining and would dramatically reduce the operational cost. The Compact Loader/Trammer, known as the "mini-mucker" has been developed to increase productivity of the load/haul/dump portion of the typical narrow vein mining cycle. This is Volume II of the final report and concerns the operation and maintenance of the mini-mucker. Volume I covers a general and design review of the activities on the subject contract and are available under separate cover.

Jan 1, 1985

By J. E. Allison

As part of a Bureau of Mines research program to conserve critical and strategic metals, an aqueous electrodeposition method for preparing stainless-steel-type coatings was studied. Chromium powder (averaging 3 J1.m diam) was suspended in a ferrous-nickelous sulfate electroplating bath and occluded in the electrodeposited Fe-Ni alloy matrix. Subsequent heat treatment of the resulting composite coating formed the ternary alloy. The occlusion process was affected by the quantity of Cr powder suspended in the electrolyte and by the microstructure and composition of the electrodeposited matrix. Coatings containing up to 21 wt pct Cr were deposited from an electrolyte containing 20 vol pct suspended Cr powder. Heat treatment at 1,100° C for 8 h homogenized the composite coating. Deposition of 44Fe36Ni20Cr alloy coatings (250 J1.m thick) on AISI 1020 carbon steel rods, followed by heat treatment, provided complete protection of the carbon steel during exposure to a boiling 65-pct-HN03 solution. Corrosion rates of 0.6±OA mm/yr for the coating in the boiling HN03 approximate that of 304 stainless steel. Practically shaped electroforms have been prepared by the coating method.

Jan 1, 1989

By Noel N. Moebs

The U.S. Bureau of Mines is conducting research on many topics relating to the mineral resources of the United States. This is done to ensure an adequate supply of minerals essential to a viable domestic industry and a sound economy. The United States is almost totally dependent on foreign supplies for a number of minerals such as chromium, niobium, tantalum, and manganese for which there is no available substitute, while many other minerals such as titanium are abundantly distributed throughout the earth but seldom occur in adequate concentrations or useful forms. This report describes an example of a small but high-grade occurrence of titanium are in Nelson County, VA. This occurrence could be exploited under favorable economic conditions with new mining technology such as borehole slurry mining. The report demonstrates that the dikes at titanium ore, a mixture of ilmenite and apatite locally termed nelsonite, can be detected and traced along strike using magnetometer traverses. This information will aid in the selection of appropriate slurry borehole mining test sites in the area.

Jan 1, 1993

By Paul E. Loustaunau

This report describes a project in which three structured underground coal mine equipment operator training programs were developed. The project was carried out in two parts. In the first part, a research study was conducted to determine how on-the-job training is currently conducted in industry, and to determine the overall effectiveness of current on-the-job training. In addition, the possible application of the principles of social learning theory to on-the-job training was investigated. In the second part three prototypes on-the-job training programs were developed for shuttle car operation, roof bolter operation, and continuous miner operation. These programs were carefully structured to eliminate the shortcomings of current industrial on-the-job training identified in the research study and incorporated the application of relevant principles of social learning theory. The programs are prototypes which underground coal mine training personnel can use as models to develop their own customized equipment operator training programs.

Jan 1, 1983

By G. S. Scott

In the course of the investigation into the causes, behavior, and control of mine fires, which the Bureau of Mines is now conducting, some attention was given to the subject of spontaneous heating. It is self-evident that the temperature of a pile of broken coal will rice if the rate of generation of heat exceeds the rate of brat dissipation and will fall if the opposite is the case. Factors that affect the rate of generation of heat are:

Jan 1, 1941

By Paul Hatmaker

Lime was a highly useful commodity thousands of years before the simple chemistry of its manufacturing process was known. The employment of lime for agriculture, building, and even certain essentially chemical purposes is so old that its origin is among the unrecorded details of man's first ventures into the manufacture and use of prepared substances. Lime is a most versatile material and consequently has come to be widely utilized in modern civilization. Immediately before the depression of the early 1930's the annual production of lime in the United States was more than 4 million tons, valued at 33 to 42 mil-million dollars. This output was sold to many industries, so many that mere enumeration becomes tedious.

Jan 1, 1934