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By Brian T. Brady

The year 1992 recorded unimpressive economic growth and uncertainties over what changes would occur for the financial market. Falling interest rates in the United States and elsewhere tended to exert a number of positive influences on financial markets and, indirectly, the mining and quarrying industry. The interest rate declines during 1992 were no exception. Lower rates prompted many investors to turn their attention to long-term investments such as stocks that offer potentially greater rates of return, causing large cash inflows into the equity market. Lower rates made it easier for businesses to finance growth and for consumers to finance the purchase of products businesses made. Also the rates enabled many companies to increase their health and profitability by refinancing their existing loans at lower rates. Falling interest rates were not confined to the United States. With Japan and Western Europe in the midst of economic slumps, marketing authorities in many countries overseas lowered rates in an effort to stimulate business activity. True to form, that contributed to stock market rallies abroad. Stabilizing inflation and lower interests stimulated the industry during 1992 and will likely influence favorably the industry for the next few years.

Jan 1, 1992

By Bruce D. Hanson

The Bureau of Mines conducted a series of experiments using four different coal types to determine the effect of attack angle and symmetric bit wear on airborne respirable dust (ARD) generated by point-attack bits and in energy consumption. Neither had a significant effect on ARD at the 95-pct confidence level, but bit wear had a significant effect (95 pct confidence) on specific energy (energy per gram of cut coal) for three coal types, Depth of cut was the most significant factor affecting ARD and specific energy.

Jan 1, 1979

By R. F. Droullard

The Bureau of Mines has used gross alpha and gross beta detectors to continuously measure radiation working levels for a number of years. During this time, improvements have been made in the design and performance of continuous working-level (CWL) detectors. This report discusses the improved designs and some of the operating principles and applications of CWL detectors in the measurement of radon daughter products in mines and dwellings.

Jan 1, 1985

By K. C. Dean

Fine-sized mineral wastes discarded by ore milling plants require stabilization to prevent air and water pollution. Stabilization has been attained by physical, chemical, vegetative, and combination procedures. Vegetative reclamation is preferred to physical and chemical stabilization but is diffi¬cult to achieve because the wastes are sterile, contain deleterious inorganic salts, and lack the essential nutrients and physical characteristics required for sustaining vegetative growth. Methods now have been developed for attain¬ing vegetative growth on all but excessively acidic, basic, or saline tailings at costs ranging from $120 to $650 per acre. The cost for stabilizing tail¬ings requiring more intensive treatment techniques may range upward to $1,750 per acre. This report summarizes procedures developed by the Bureau of Mines and industry for vegetating amenable tailings, lists costs for the various processes, and suggests procedures that may be applicable for stabilizing saline and pyrite-containing tailings. Ridged planting beds, drip irrigation, and deep-furrow planting techniques are suggested for stabilizing saline wastes. A combination of mill tailings and sewage sludge can be used for pro¬ducing synthetic soils, and layers of sewage sludge buried under a layer of tailings offer promise of inhibiting acid formation from oxidation of sulfides in mineral wastes.

Jan 1, 1974

By J. R. Cobble

Dissolution of chalcopyrite with acidified ferric sulfate produces a sulfur layer on the unreacted chalcopyrite surface that interferes with further dissolution. The U.S. Bureau of Mines has developed a process to improve the leaching kinetics of these types of diffusion-controlled systems. The system features the Bureau-developed turbomill, an attrition grinder that scrubs the reaction product coating away from the unreacted mineral grains during leaching. The system can be operated continuously at any temperature up to the boiling point of the leaching agent. This method is a hydrometallurgical alternative to chalcopyrite smelter technology and eliminates sulfur dioxide emission problems with its associated costs. Batch testing at 900 C with the chalcopyrite-ferric sulfate system resulted in copper extraction exceeding 99 pct. At an optimal energy consumption of 1,520 kW· hjst, 95 pct of the copper was extracted. The pregnant liquor was clarified and tested for typical solvent-extraction recovery of the copper. Two-stage extraction and two-stage stripping recovered 96 pct of the copper in an electrolyte suitable for copper electrowinning.

Jan 1, 1993

By M. P. Dalton

This paper which describes the milling practice at the Morning concentrator of the Federal Mining and Smelting Co., Mullan, Idaho, is one of a series being prepared by the Bureau of Mines. ACKNOWLEDGMENT The author wishes to acknowledge the assistance given by H. G. Washburn, general manager of the Federal Mining and Smelting Co., and by C. S. Price, assistant mill superintendent, in the preparation of this paper.

Jan 1, 1932

By G. S. Scott

The investigation of the causes, behavior, and control of anthracite mine fires, which the Bureau of Mines has been carrying on has yielded several publications directly applicable to mine-fire problems. 3/, 4/, 5/, 6/, 7/, 8/ As a further step in elucidating the causes of heating in certain anthracites subjected to oxidation, reliable information vial needed relative to the actual amount of heat that is liberated when a unit volume of oxygen combines with anthracite at varying temperatures.

Jan 1, 1939

By J. A. Kosek

Work has been carried out under Bureau of Mines Contract HO 395132 to develop improved sensor cells for use in direct-reading detectors and diffusion exposure meters. A pumped CO sensor cell was developed which has a shorter response time, improved temperature cycle characteristics, and improved linearity and stability at high CO concentrations. Diffusion CO sensor cells have shown good response level stability and linearity up to 1000 ppm. In addition, a new sensor cell catalyst has been developed for NO2 sensor cells which has a much shorter response time and improved response stability characteristics.

Jan 1, 1982

By Kenneth M. Earl

In its program of investigation of deposits of strategic minerals, the Bureau of Mines did some development drilling at the Douglas Deposit in an attempt to find an additional source of supply of copper. The deposit, which was opened in 1878, was worked until 1883 and is reported to have produced between 2 and 3 million pounds of copper. Heap-roasting and smelting and later gravity concentration were employed in ore reduction. Old slag dumps and tailing piles from these operations still remain. In 1917, the American Smelting & Refining Co., purchased the mine, and in June 1918 production was started in a 125-ton mill, using both tables and flotation. The mill was closed December 31, 1918, and soon after the milling plant Was dismantled and removed. The mine has remained idle ever since. The deposit occurs in a mineralized zone that follows the schistosity. The principal metallic minerals are pyrite) chalcopyrite, pyrrhotite) arsenopyrite, sphalerite, magnetite) slight chalcocitel and cuprite. To search for additional ore shoots and to prove the known ore shoot at depth, the Bureau of Mines drilled seven holes, which totaled 2,117.4 feet. No additional ore was developed by this work.

Jan 1, 1950

By S. P. Kinney

[The blast-furnace operator is often confronted with the problem of determining the size of the materials which are used in the furnace burden. The statement is heard that the coke is larger or smaller or that certain ore is finer than that previously used. A screen analysis of the materials used gives a measure of the different sizes of materials in an aggregate. When one is fine and the other is coarse, the difference is obvious; but when the materials are of similar sire, it is more difficult to estimate the degree of finances or coarseness. In considering raw materials it would be desirable to be able to judge the size of the radio ideal materials entering the furnace and the burden as a whole, by one representative value, such as the average size of particle. Previous work by Perrott and Kinney3 developed a method for measuring the average size of particle in a mass of finely ground materials, and an attempt will be made to apply this method to the materials included in the blast-furnace charge and to the entire burden.]

Jan 1, 1930

Table 1.-Salient statistics of carbon black produced from natural gas and liquid hydrocarbons in the United States [ ]

Jan 1, 1967

By Chas. F. Jackson

The work of the mining division is divided between seven sections, each in charge of a supervising engineer, as follows: 1. Metal-mining methods section, the supervising engineer of which is also supervising engineer of the Southwest Experiment Station at Tucson, Ariz. 2. Metal-mining research section. 3. Nonmetal minim section. 4. Coal-mining section. 5. Mine-ventilation section. 6. Mineral-industries survey section. 7. Electrical section. The names of the sections indicate broadly the fields covered by each, and in the following pages the objectives and type of work of each section will be summarized briefly and the active problems listed. The work done during the calendar year 1936 will also be summarized.

Jan 1, 1937

By Cleo Griffith Rall, D. B. Taliaferro

The method for determining oil and water saturations described herein has been used successfully for several years in the core laboratories of the Bureau of Mines. The apparatus constructed according to the original specifications has proved very satisfactory; in fact, it has been widely adopted by core laboratories throughout the petroleum industry. The writers have found that the method gives reproducible results, the degree of accuracy depending largely on the attention to details given by the operator. The relative importance of these details of procedure and the design of the apparatus are discussed in this report. In September 1940, the Bureau of Mines published a report describing a method used in its laboratories for the determination of the water content of oil-field cores. The procedure was essentially the same as that adopted by the American Society for Testing Materials for the determination of the water content of petroleum products, although the apparatus and technique were altered slightly to increase the precision of the method and to adapt it to the characteristics of the material to be tested. The report also contained a description of the method used at that time in the Bureau’s core laboratories for measuring the oil content of a core, utilizing the sample on which the water-saturation determination had been made. The procedure involved the transfer of the weighed sample, from which the water had been distilled and measured, to a Soxhlet extractor and the removal of the remaining oil by means of a suitable solvent. Soon after the report was published, the water-determination apparatus described therein was modified so that both the oil and water contents of a core sample could be determined simultaneously. This method, which has been described by Yuster, is now widely used throughout the industry.

Dec 1, 1946

By P. L. Swanson

Stability analyses of fractured and faulted rock masses require delineation of the position, extent, and orientation of geologic discontinuities. The size of the smallest active discontinuity that may potentially be resolved using the spatial distribution of microseismic event locations is Limited by the accuracy and precision of the location methods. At a hard-rock mine in the Coeur D'Alene mining district of northern Idaho, two data sets consisting of calibration blast signals from a known source site and origin time and microseismic event signals were recorded using a stope-wide accelerometer array. These seismic signals are used to quantify various sources of error in event location. Five factors influencing source location errors are examined in this U.S. Bureau of Mines study: (1) biases of the numerical source location techniques, (2) receiver array geometries, (3) uncertainties in receiver positions, (4) errors in picking arrival times, and (5) uncertainties in seismic velocity structure, including the effect of mine openings. In addition, synthetic data (accelerometer positions, travel-time picks and wave velocity) are used to determine the effect of known systematic and random errors on source location calculations. It is shown that the commonly accepted association of minimum travel-time residuals with the best location solution does not necessarily hold true when there is a systematic error in seismic velocity. Recommendations are made for increasing the accuracy and precision of locations of microseismic events detected under similar field conditions.

Jan 1, 2010

By D. D. Harbuck

To decrease reliance on foreign sources for the strategic and critical metals gallium and germanium, the U.S. Bureau of Mines identified and developed processing technology for two domestic sources of these metals: a Tennessee zinc residue and a Utah ore. Sulfuric acid (H2S04) solutions were used to solubilize gallium and germanium in both sources. Statistically designed experiments showed that the most important parameter for high metal extraction from zinc residue was the H2S04 concentration. At a concentration of 2.9M H2S04, 95 pct of the gallium was extracted, and at a concentration of 0.6M H2S04, 73 pct of the germanium was extracted. Controlled H2S04 concentration was also the key for high metal extractions (97 pct Ga, 87 pct Ge) from the Utah ore. Such control was achieved using a two-stage countercurrent leach circuit. Testing showed that the insoluble germanium in both the residue and ore was tied up with silica. Several methods for overcoming this problem are given. To recover gallium and germanium from the leach solutions, the solvent extractants octylphenyl acid phosphate (OPAP) (for gallium) and LIX 63-OPAP (for germanium) were identified. These extractants were tested in separate, continuous, solvent-extraction circuits yielding a gallium recovery of 94 pct and a germanium recovery of more than 90 pct.

Jan 1, 2010

By R. F. Droullard

The Bureau of Mines has developed test facilities for use in a research program that deals with radiation hazards in mining. This report describes the radon test chamber located at the Denver Research Center and the Twilight experimental mine located near Uravan, CO.

Jan 1, 1984

By Albert W. Cox

This paper, one of a series prepared for the United States Bureau of Mines discussing the methods used in mining, crushing, and grinding materials for cement manufacture, deals particularly with the methods used at the Security plant of the North American Cement Corporation. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local operating expenditures only and not total production costs. It is recognized that publication of, total production costs might in many instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scone of the cost tabulations shall ensue.

Jan 1, 1932

During 1990-1999, a total of 458 fires occurred in all coal mining categories; 157 of those fires caused 164 injuries and 2 fatalities. The greatest number of fues and fire injuries occurred at surface mines, whch also had the highest risk rate values. A total of 66 fuefighting interventions were required. Of these, there were 25 mine rescue team interventions in underground mines, including 5 mobile equipment firefighting interventions, and 41 fire brigade and fire department interventions at all surface operations, including 19 mobile equipment interventions. In all, 50 fires destroyed or heavily damaged equipment (including 16 pieces of mobile equipment) because of failure of other firefighting methods, late fire detection, undetected fires, or fire size. A total of 1 14 fires were detected late by smoke, and 42 fires were not detected.

By Richard F. Hewlett

Computing average grade and tonnage either for an entire ore deposit or for individual blocks of ore is a continuing problem in mining. As part of a research program, investigating application of statistical techniques to mine sampling, Bureau of Mines engineers at the Denver Mining Research Center have made extensive use of an electronic digital computer for developing mine sampling theory, simulation of ore deposits, and analysis of mine sample and assay data. This report is one of a series describing use of the digital computer for rapid solution of computing problems in the mining industry.3 4 Development of a computer program to compute ore reserves by the commonly used triangular method was necessary so that results could be made available for analysis within hours.

Jan 1, 1963

By J. B. Zadra, H. J. Heinen

Electrowinning molybdenum from oxide feed materials dissolved in a variety of molten baths was investigated . A NaCl - NaF - Na₂ B₁ O -Mo0, system operating at 1,000 ° C in a cell without a protective atmosphere gave the best current efficiency , metal - to - cathode adherence , and purity of electrowon Technical - grade molybdic oxide , containing associated impurities of aluminum , iron , copper , silicon , and tungsten in combined quantities of 10 percent , was used as feed material to produce dendritic crystals of molybdenum metal containing less than 0.5 percent total base metal , carbon , and oxygen impurities . Arc - melting molybdenum electrowon from either chemically pure or commercial - grade Mo0, produced ingots that contained less than 0.1 percent total impurities and had hardness readings of 168 to 200 Vhn .

Jan 1, 1964