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By D. L. Paulson

The Bureau of Mines is investigating pyrometallurgica1 and" chemical methods to recover valuable constituents from metallurgical dusts and slags. Under this program a technique was developed to recover iron from molten copper smelting furnace slags by carbon injection. Slags from gas-fired reverberatory and electric copper smelting furnaces were treated in an 800-kva electric-arc furnace by injecting coke breeze into the bottom of the molten bath. Over 95 pct of the iron and over 90 pct of the copper contained in the smelting furnace slags were recovered, while up to 85 pct of the carbon injected into the system was utilized. It is anticipated that the metal product containing approximately 95 wt-pct iron and 2 wt-pct copper will be a satisfactory medium for recovering copper by cementation.

Jan 1, 1977

By Kevin Connor

The mineral industry continued to be an almost negligible contributor to the country's economy as the Government continued its 1979 ban on any mineral exploitation for export; a policy initiated at the end of 1979. A national program had been underway since that time to map and inventory all mineral resources so as to permit future exploitation of mineral wealth in the beat interests of the country and its inhabitants. In March 1982, the British Sulphur Corp. Ltd., under contract to the Burundi Government and the International Bank for Reconstruction and Development (World Bank), began a feasibility study of Burundi's phosphate deposits at Matongo-Bandaga for potential commercial exploitation. The 1-year project effort was to define ore reserves, conceptually design mining operations and processing facilities, estimate capital and production cost, and develop a regional market and distribution survey. Work completed during the year comprised geological exploration and reconnaissance and 1,200 meters of core drilling. Reserves in excess of 5 million tons of ore-grade phosphate were estimated available for mining. Rare earth mineralization was associated with the primary apatite. The associated carbonatite within the rock matrix was preliminarily assessed to be of value as a raw material for the manufacture of cement. The contract effort was valued at $1.2 million? Matongo-Bandaga is located approximately 40 kilometers north of the capital city of Bujumbura and alongside one of the country's few paved roads.

Jan 1, 1984

By W. Blake, J. K. Whyatt, T. J. Williams

Researchers at the U.S. Bureau of Mines collected and analyzed over core measurements and other indicators of in situ stress characteristics at the Lucky Friday Mine, Mullan, ID. An analysis of these data revealed that significant local variations in in situ stress are present in this mine and that these variations existed prior to mining. High stresses were found to be associated with the most competent strata and a locked section of a fault. An estimate of the predominant stress field was developed for mine-wide modeling. The estimate shows that the greatest principal stress was oriented north of northwest. This information should provide a basis for mine-wide structural modeling of the Lucky Friday Mine and should generate important insights into localized stress conditions, which may significantly affect both local and mine-to-mine variations in seismicity induced by excavation.

Jan 1, 1995

By D. Litton, H. Dobroski, J. G. Kovac

Since 1910, the U.S. Bureau of Mines (USBM) has investigated practical ways of dealing with the consequences of major fires and explosions in underground mines. The results of this research have had a significant positive impact on the mining community by enhancing mine workers’ chances of surviving an underground mine disaster. Today, the Bureau continues to conduct research in mine disaster mitigation. Much of this work has direct application to search and rescue situations, such as: emergency evacuation through smoke-filled or otherwise unbreathable atmospheres, locating and rescuing survivors from rubble piles, and fire fighting in confined spaces. Three USBM research areas are discussed: (1) Life Support -- This effort is directed toward research into and development of closed-circuit breathing apparatus for use in hazardous environments which are likely to be encountered in the aftermath of a mine disaster. (2) Trapped Miner Location -- A mine disaster may result in the entrapment of miners whose normal escape routes are cut-off. This research activity resulted in the development of transportable seismic technology that can be used to locate trapped miners. (3) Mine Fire Diagnostics -- This research involves developing practical techniques for remotely monitoring how the atmosphere inside a mine changes during a fire, in order to estimate the spread and severity of an underground fire. This information is critical in deciding how best to fight a mine fire, or whether it is safe to mount a rescue and recovery mission.

By M. L. Whisman

The Bureau of Mines developed a radiotracer method for detecting the contribution of selected components and additives to thermally induce deposits of turbine aircraft fuels. Fuels were examined before and after 52 weeks of storage at 130° F. Of particular concern was the influence of aromatic hydrocarbon fuel constituents on thermal-stability quality of jet fuels during storage. A microfuel coker test apparatus was used to thermally stress the test fuels and blends, and the resultant contribution to deposits of selected fuel components, labeled with carbon-14, was determined by radioactive-counting techniques. Ninety-one blends of five test fuels with carbon-14-labeled fuel additives or components were prepared, tested, stored for 52 weeks at 130° F, and reanalyzed for deposit-forming tendency. These additives included two anti-oxidants, a metal deactivator, and a corrosion inhibitor. Of the labeled hydrocarbon fuel systems studied, the greatest reaction was observed in blends containing methyl-and ethyl-substituted indenes. Other aromatic types also showed some contribution to the deposits. Three of the additives showed a marked tendency to degrade and react during storage and thermal stress. A cresol antioxidant, however, barely contributed to deposit formation. Oleic acid interacted with cadmium present in aircraft fuel systems and produced deleterious effects upon the thermal-stability quality of the fuel.

Jan 1, 1971

By B. Dimitriades

The Bureau of Mines measured the reactivities of 19 hydrocarbons known to be prominently present in automotive exhaust and ambient air in a smog chamber. Results agreed well with those obtained using two other smog chambers. Reactivity scales were developed for hydrocarbons and aldehydes using the results of this work and those of a previous study. Application of the reactivity scales to automotive exhaust samples gave fair agreement between predicted and observed rate-of-N02-formation values; however, predicted and observed ozone yields were neither in agreement nor did they correlate well. This lack of correlation for ozone yield was attributed to the inappropriateness of (1) the individual component reactivity data, (2) the reactivity classification scheme used, and (3) the linear summation method. In seeking to understand this problem and to develop more appropriate reactivity scales, the data were examined from a reaction mechanism standpoint, and further studies were suggested.

Jan 1, 1975

By Nicholas Kyriazi

Significant portions of the present Federal regulations for certification of closed-circuit breathing apparatus (42 CFR 84) are not quantitative. The human-subject testing portion of the regulations specifies activities rather than metabolic work rates; however, heavy human subjects have higher oxygen consumption, CO2 production, and ventilation rates than lighter human subjects performing the same activities. This means that apparatus certified using different human subjects have effectively passed different tests. In addition, apparatus performance is monitored only during selected intervals of testing, and always during rest, rather than during the entire performance period. Further, testing is arbitrarily terminated at specific rated durations, leaving unknown the performance during the remaining duration. Duration itself is misleading to users who believe that the apparatus will last a certain time no matter how much they weigh or how hard they work. The actual duration obtained from an apparatus, however, is highly variable, being inversely proportional to the work rate at which it is used. In this report, recommendations are made to (1) replace the present regulations for certification of closed-circuit breathing apparatus with quantitative tests specifying metabolic work rate rather than activity,(2) continuously monitor relevant physiological stressors, (3) continue testing until exhaustion of the oxygen source, and (4) classify closed-circuit breathing apparatus by quantity of usable oxygen, i.e., capacity, rather than by duration. Physiology-based stressor levels are suggested as well.

Jan 1, 1999

By J. W. Paul

This paper deals with the third phase of on extensive research on coal-mine ventilation factors. A comprehensive report of the entire work is in course of preparation, but abstracts of the various chapters are being prepared in order to make the results public as rapidly as possible. Parts I and II of this paper were issued Serial 2621 and Serial 2647 of the Bureau of Mines in July and October, 1924. They dealt with the resistance of unobstructed entry and the resistance caused by mine cars in untimbered entry. Description of the Tests After the resistance of unobstructed entry and of mine cars in untimbered entry had been determined by tests in the Experimental Mine, three different types of timbering were installed in the test section and the increased resistance caused by the timbering was determined.

Jan 1, 1925

By T. M. Ruff

A prototype mucking machine designed to operate in narrow-vein stopes was developed by Foster-Miller, Inc., Waltham, MA, under contract with the U.S. Bureau of Mines. The machine, called a compact loader-trammer, or minimucker, was designed to replace slusher muckers in narrow-vein underground mines. The minimucker is a six-wheel-drive, skid-steered, load-haul-dump (LHD) machine that loads muck at the front with a novel slide-bucket system and ejects it out the rear so that the machine does not have to be turned around. To correct deficiencies of the tether-remote-control system, a computer-based, radio-remote-control system was retrofitted to the minimucker. Initial tests indicated a need to assist the operator in guiding the machine in narrow stopes. An automatic guidance system that used ultrasonic ranging sensors and a wall-following algorithm was installed. Additional tests in a simulated test stope showed that these changes improved the operation of the minimucker. The design and functions of the minimucker and its computer-based, remote-control system are reviewed, and an ultrasonic-sensor-based guidance system is described.

Jan 1, 2010

Detemine the elastic properties and structural integrity of a rock mass in situ. Approach An acoustic device that transmits and receives high-frequency seismic waves between boreholes was designed, built, and field tested. How It Works The acoustic cross-borehole apparatus operates by sending a seismic wave from a transmitter in one borehole to a receiver in a second bore? hole which may be located as far as fifty feet away, depending on the wave transmission quality of the rock. By measuring the wave's travel time and the distance between boreholes, the acoustic velocity of the rock mass can be determined. Characteristics of the seismic wave arriving at the receiver (such as the wave velocity, amplitude, and frequency content) are related to the physical properties of the geologic media, as calcu-

Jan 1, 1982

By E. G. Valdez

The Federal Bureau of Mines, in cooperation with Ford Motor Co., investigated the recovery of polyurethane foam and other assorted plastics from the nonmagnetic reject of automobile shredders. Preliminary studies were con-ducted on a 1957 hulk augmented with additional foam and assorted plastics. The proposed flowsheet developed by the Bureau from the preliminary studies consists of a combination of screening, water classification, and gravity separation. The process was then tested on reject from two shredded 1972 cars. All of the foam and between 52 and 70 pct of the assorted plastics were recovered. The composition of the reclaimed foam concentrates ranged from 46 to 66 pct foam; the concentrates were hydrolyzed in laboratory tests by Ford Motor Co. to produce a reusable liquid mixture of polyether glycol monomers and toluene diamine.

Jan 1, 1975

By Daniel C. Boteler

Data from 68 entrained-bed carbonization tests were treated statistically by the Bureau of Mines, and several useful relationships were developed among the major variables. Nine coals, ranging in rank from lignite A to high-volatile A bituminous, were carbonized in two entrained-bed carbonization pilot plants. The carbonizing reactors employed were vertically mounted cylinders, internally heated, refractory-lined, and 10 inches ID. The range of carbonization temperatures was from 825° to 1,600° F. Using a regression-analysis computer program, empirical equations were developed by which carbonization temperature, air-to-coal ratio, devolatilization of coal, char yield, and volatile matter content of product char may be predicted.

Jan 1, 1973

By B. T. Brady

Laboratory measurements by the Bureau of Mines indicate that failure in dry rock specimens measuring approximately 13 cm in length is preceded by tilt anomalies lasting a few milliseconds. The tilt behavior is qualitatively similar to that reported to precede earthquakes. Test results suggest that the time duration of this tilt anomaly for laboratory specimens of this length is independent of rock type, in agreement with theoretical predictions and other experimental data on rock failures including earthquakes.

Jan 1, 1975

Provide an operator cab to assure protection, comfortable use of controls, and good visibility. Approach A cab which raises and lowers by pivoting about d horizontal axis was Installed on two S&S cleanup tractors and tested in two underground working mines. How It Works Hydraulic cylinders actuated by a lever inside the cab cause the cab to pivot about a horizontal axis. This action raises or lowers the cab height. The total cab excursion is 14 inches. A release valve in the hydraulic system allows the cab to lower automatically if struck by a roof load or overhead obstruction. The pivoting action of the cab is engineered so that the operator maintains comfortable use of all controls at all cab heights. The movement is such that the angular relationship of the operator's ankles With the tram and brake foot controls IS consistently within 90 to 100 degrees. Figure 1 outlines the approximate position of the operator at three cab elevations.

Jan 1, 1977

To develop a cost-effective tool for improving the performance of rock drilling systems used in detecting and delineating underground mine voids and for coal exploration. Approach To investigate admixtures of polyethylene oxide (PEO) at zero surface charge concentrations as drilling fluid additives to enhance penetration rates and extend bit life in rock drilling systems. Background Bureau researchers have investigated the use of chemical additives to enhance drilling performance and found that the most efficient drilling occurred when the drilling fluid was able to maintain a zero surface charge (ZSC) on the surface of the rock being drilled. Laboratory drilling studies have been performed on rock types such as quart¬zite, granite, taconite, and marble. The lab tests were conducted using 5/8-inch diameter diamond-impregnated coring bits with cationic compounds as the surface charge neutralizing additives. These studies demonstrated enhanced drilling performance, however, only at the singular additive concentration that produced the ZSC condition.

Jan 1, 1991

Reduce the dust levels to which jacksetters and helpers on auger mining sections are exposed by identifying viable, effective methods for control-ling respirable dust on these sections. Approach The Bureau of Mines con-ducted laboratory tests and respirable dust surveys to identify the factors that distinguish clean auger mining operations from dusty ones. Study Results Results of the Bureau's study revealed that ventilation is the most important element of auger mining dust control. The four must important venitilation parameters are airflow, curtain configuration, curtain setback, and curtain installation.

Jan 1, 1988

By Aarne Visnapuu

Pneumatic chipping, scaling, and grinding can expose the tool operator to noise levels in the range 90 to 120 dbA. In most chipping and scaling operations, casting resonance is the primary source of noise, followed by air exhaust, and machine and chisel resonance. In grinding, the air-exhaust noise predominates. The Bureau of Mines has shown that noise from these operations can be reduced by up to 15 dbA. Workpiece resonance was reduced by sand or other damping methods; tool resonance, by internal damping; and chisel resonance, by constrained-layer treatment. Mufflers reduced air-exhaust noise, and an acoustically treated booth was effective in containing noise around the work area without increasing operator exposure.

Jan 1, 1977

By D. B. Dow

"In the natural-gas Gasoline industry, the methods used in determining the amount of gasoline in natural gas are many and varied; they include the specific-gravity test, laboratory tests involving absorption, charge in volume of the gas or in the absorption medium, absorption in charcoal with subsequent distillation, compression of the gas which results in the condensation of the gasoline, and the absorption of the gasoline vapors in an absorption oil, from which the gasoline is distilled and measured. Each of these various tests has advantages, and disadvantages. It is however, conceded in the industry that the tests in which the gasoline is obtained and measured as such are the more reliable.This paper deals with certain factors which should be considered in making absorption tests using ""mineral seal oil"" as an absorbent; this method of testing is widely used not only in the field, but in control work in absorption gasoline plants where the gasoline content of the intake and discharge gas is determined daily. In control work it is frequently found that the plant produces more gasoline than the tests show, which gives the plant the appearance of making more gasoline than is actually present in the gas treated, or in other words operating at more than one hundred per cent efficiency. Obviously then, the tests as made in these cases are in error, and in hope of correcting some of these variances, the following factors have been studied at the U. S. Bureau of Mines petroleum station at Bartlesville, Oklahoma."

Aug 1, 1920

By D. N. Nilsen

The Bureau of Mines is developing a method to recover Ni, Co, and Cu from laterites containing less than 1.2 pct Ni and 0.25 pct Co. The method consists of the following basic unit operations: (1) reduction roasting, (2) leaching, (3) solvent extraction, and (4) electrowinning. The method reflects three Bureau of Mines objectives: (1) recovery of critical minerals that are domestically in short supply from low-grade domestic laterites, (2) lower processing energy requirements, and (3) solution recycling. This report deals with the extraction of cobalt and the preparation of a suitable cobalt electrolyte by solvent extraction from liquor produced by this method. Nickel and copper are coextracted with LIX64N from an ammoniacal ammonium sulfate leach liquor containing about 1.00 g/l Ni, 0.30 g/l Co, 0.03 g/l Cu, and 0.02 g/l Zn. Cobalt (III) in the nickel-copper barren raffinate is reduced to cobalt (II) with cobalt metal. Reduction of cobalt (III) to cobalt (II) greatly aids subsequent extraction. Commercially available XI-51 extracts about 94 pct of the cobalt from the treated raffinate in one stage in a laboratory mixer-settler continuous circuit. Ammonia loaded on the solvent is removed in two washing steps. About 94 pct of the cobalt then is stripped from the XI-51 in one stage with spent cobalt electrolyte containing about 77 g/l Co and 18 g/l sulfuric acid (H2S04), Electrolytes containing less H2S04 also may be used. Preliminary data indicate that coextracted zinc may be removed from pregnant cobalt eletrolyte containing 3 g/l or less H2S04 with di-(2 ethylhexyl) phosphoric acid (D2EHPA).

Jan 1, 1980

By Joseph A. Sutton

The prospect of utilizing bacteria in mining and metallurgical processes introduces a new and challenging area of investigation. Elements of bacteriology and metallurgy are discussed in connection with possible areas where biological science might be applied in extractive metallurgy. Bacteria may prove important in the selective separation of metals from ores and metallurgical solutions, the production of sulfur from gypsum or pyrites, and the production of sulfuric acid from elemental sulfur. A series of reports concerning the experimental applications of bacteria on minerals and metallic ores will follow this paper. For several years the Bureau of Mines has been investigating the action of bacteria in the oxidation of sulfide minerals and their potential uses in metallurgical processes. Primary attention has been given to the possible utilization of certain strains of autotrophic bacteria that live in industrial leaching solutions or fractures of mineral outcrops. The purpose of this paper is to acquaint the mining and metallurgical engineer with micro-organisms and some of their possible applications in the field of extractive metallurgy.

Jan 1, 1961