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By R. S. Olsen

The Bureau of Mines is engaged in a continuing research effort toward the recovery of alumina from kaolinitic clay and other nonbauxitic domestic minerals. Hydrochloric acid extraction of calcined clay is among the acid processes under consideration. Although aluminum is easily leached from calcined clay, the presence of fines and slimes in the leached residue has hindered the application of this and other acid leaching processes. A clay feed preparation method was therefore developed that eliminated the slimy nature and the separation problems normally associated with leached clay residues. The preparation process consists of crushing the raw clay to minus 20 mesh, dampening the crushed clay with a fine water mist while tumbling on a rotating disk, and calcining the misted clay at 750° C. The misting process increases residue settling rates threefold to 9 cm/min (18 ft/hr) and filtration rates by two orders of magnitude. Leaching-kinetics were determined for misted clay feeds in a batch, stirred-tank reactor. Rapid leaching occurred during the first 85 to 90 pct of the extraction. The linear relationship of extraction to time during this initial phase corresponded to a zero order reaction with a rate constant of around 10 pct/min.

Jan 1, 1981

By D. L. Pool

To increase metal recoveries and to minimize pollution by improved extraction technology, the Bureau of Mines investigated a hydrometallurgical technique to recover copper, lead, nickel, and cobalt from lead smelter mattes. The metals were converted from insoluble sulfides to soluble chlorides using a HCI-CI2-02 leaching system. Parameters studied in a 50-gallon, glass-lined reactor were the ratio of hydrochloric acid to chlorine, chlorine consumption per pound of matte, oxygen reaction pressure, and temperature. The matte material used contained, in percent, 19.7 Cu, 52 Pb, 2.9 Ni, 1.5 Fe, 0.38 Co, 0.19 As, 0.41 Zn, and 0.12 Cd. Extraction of Cu, Pb, Ni, Co, and Cd ranged from 92 to 98 pct, with concomitant extractions of Fe and As of <0.1 pct. The Cu and Pb were recovered as electrowon metals, while the Ni, Co, and Cd were recovered as mixed hydroxides.

Jan 1, 1981

By D. W. Frommer

Processing of nonmagnetic taconites by selective flocculation-des liming and anionic flotation of calcium-activated silica has been investigated using innovative procedures as a means of improving operating costs. Areas chosen for cost-cutting evaluation were grinding, fine screening, and water conservation and reclamation. The investigation was performed on Marquette range nonmagnetic taconites in the Bureau of Mines Twin Cities Metallurgy Research Center flotation pilot plant, at feed rates ranging between 900 and 1,100 lb/hr. With fully integrated water reclamation, flotation concentrates containing 65.8 percent Fe and 3.4 percent Si02 were made in the best operating period, with accompanying weight and iron recoveries of 40 and 74 percent, respectively. During this same period, the estimated cost of both flotation and water reclamation reagents was only $0.80 per ton of concentrate (1968 pricing basis). This cost is about 15 percent lower than obtained previously at this Center for flotation reagents only. The investigation demonstrated additional potential savings in operating costs of approximately $0.96 per ton of concentrate through autogenous grinding as a substitute for ballmilling. Fine screening of intermediate concentrates was employed advantageously, but the frequency of blinding may be a factor militating against use of the screen in this flotation system.

Jan 1, 1973

By Jack C. White

The purpose of this Bureau of Mines work was to develop information useful in improving copper recovery during copper milling operations. Eleven copper mill tailings from the Western United States were subjected to froth flotation and cyanide leaching to provide an experimental basis for comparing their beneficiation response. Recoveries in flotation concentrates made from mill tailings ranged from 65 to 15 percent, at copper grades of 13 and 2.2 percent, respectively. Liberated copper sulfide minerals present in two samples were readily recovered by laboratory froth flotation. Nine of the samples were less amenable to froth flotation because of physical locking between copper sulfide minerals and gangue. Correlations among tailings indicated that recovery of sulfide copper by flotation was directly related to the sulfide copper content. Empirical equations derived from flotation data provided average values for unrecoverable copper and for recovery efficiency. Flotation response of copper mill tailings may be predicted from the equations. Data from cyanide leaching provides an equation describing the limiting high values for removal of copper by this method.

Jan 1, 1974

By Ivette E. Torres

For a study such as this, which summarizes and amalgamates much information collected, compiled, and utilized by the numerous U.S. Bureau of Mines country specialists and branch chiefs for inclusion in their country and regional reports that comprise the five other sections of 1992 Minerals Yearbook-International Review, it is clearly impossible to cite all sources of information used in its presentation, but some recognition is due. Generally speaking, this study and its related detailed studies on countries and areas would be much more difficult, if not impossible to complete, without the efforts of the personnel of our counterpart national mining and geological agencies throughout the world. Information that they collect, compile, and then publish, either in their own volumes or those of central statistical agencies in their countries, are the foundations on which this work rests. Thus, our appreciation is expressed to the multitude of persons employed by these agencies for their contributions.

Jan 1, 1994

By Larry Patts, Michael J. Brnich

Approximately 45% of U.S. coal is produced from underground mining. The use of diesel engines to power under- ground mining equipment has steadily increased over the past four decades in an effort to improve mine safety and productivity. Several advantages realized with the use of diesel-powered mining equipment in underground coal mines are listed in Table I. The primary disadvantage of using diesel equipment in underground coal mines is that diesel exhaust emissions can contaminate mine ventilation air. The major constituents of diesel exhaust are gaseous emissions (which include carbon monoxide, carbon dioxide, oxides of nitrogen, sulfur oxides and unburned hydrocarbons) and diesel particulate matter (DPM). The Mine Safety and Health Administration (MSHA) has incorporated threshold limit values for all gaseous components of diesel exhaust into their regulations. These have been established by the American Conference of Governmental Industrial Hygienists.

By Launa G. Mallett, Kathleen Kowalski-Trakofler, Robert H. Peters, Charles PH. D. Vaught, Peter Keating, William J. Wiehagen

On-the-job training is a common means of training or retraining workers and the practice may seem simple and straightforward. Doing it effectively however requires more thought and preparation than simply having someone follow an experienced worker around and watch what they&apos;re doing. Over the years, various techniques and practices have evolved that pass on the skills and knowledge of a trainer or coach in a manner that leads an inexperienced trainee to really absorb the information being taught. On-the-job training thus becomes less a haphazard show-and-tell and more a real transfer of information. The goal of this document is to describe how to develop or manage an on-the-job training program so that information is passed on from trainer/coach to trainee efficiently and effectively. By efficient is meant the best use of time and resources of all those involved in the training process, and by effective is meant that the trainee truly learns the skills and internalizes the knowledge needed to perform the job well. The first part of the document discusses topics to think about when developing a formal on- the-job training program. A structure based on coaching is suggested. Then a workshop designed to prepare trainers as coaches is described. Workshop materials include an instructor’s guide and trainee workbook. These materials can be used to train coaches and to assist trainees as they go through the learning process. Content related to specific jobs can be added to these materials to create targeted on-the job-training manuals. Structuring a formal on-the-job training program It is likely that some form of on-the-job training (OJT) is being conducted at your workplace. The formality of that training can range from a structured program to an informal “follow Joe around” method. If your program is completely unstructured, it may not be meeting current training needs. Worse, it may perpetuate bad habits and create “trained” employees who are not given the same information or evaluated to the same standards. Wiehagen et al. comment that, “Success in using unplanned OJT is usually dependent on the luck of the draw, that is, whether the informal trainer is competent at the task he or she is teaching, is motivated to teach, can organize the job into logical components, and knows something about good practices in teaching and evaluating” (2002, p. 27). It is only through planning a structured OJT program that consistency can be created and maintained. At the least, all trainees who have successfully completed such a program can be expected to perform at an established level—they will know what they must do to be successful.

Jan 7, 2005

By R. H. Thompson

Six different types of blasting caps, mainly of the type used in coal mines, were evaluated to determine both their 1lF and DC characteristics. Two of the caps were of foreign manufacture. All the American made caps had "no-fire" (0.1% firing probability with 95% confidence, as determined by the Bruceton test) levels above 0.04 watts. One of the caps of foreign manufacture had a "no-fire" level of 0.023 watts. A worst case analysis of blasting cap pick up of RF power in coal mines was performed and safe distance curves were generated.

Jan 8, 1973

By G. E. McClelland

As part of its mission to assure an adequate domestic supply of metals essential to the Nation&apos;s welfare, the U.S. Department of the Interior, Bureau of Mines, investigated a particle agglomeration technique as a means for improving the flow of leaching solution through heaps of clayey or finely crushed, low-grade, gold-silver ores. Bench-and pilot-scale experiments showed that the percolation rate of cyanide leaching solution was markedly enhanced by mixing the ore with a portland cement binder, moistening the mixture, and mechanically agglomerating and aging the feed prior to heap building and leaching. The rate of gold and silver recovery markedly increased because of the increased, uniform percolation of leaching solution through the agglomerated feed. The use of concentrated cyanide solution instead of water during the agglomeration procedure decreased the leaching time required to obtain maximum recovery. Results of bench-and pilot-scale experiments are discussed.

Jan 1, 1981

By Edward L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

By Clarence O. Babcock

ROCK BEHAVIOR has proved of national interest in a variety of fields. The behavior of rock consequent to a nuclear blast was used to detect such blasts, as criteria for the design of underground military defense installations that would resist nuclear blasts, and for judging the feasibility for peaceful uses of nuclear explosives. An obvious peaceful application of nuclear explosives would be for large-scale rock excavation, and plans were presented during the year to improve the present Panama Canal or create a new canal by this method. These plans were based largely on earlier crater tests that demonstrated rock behavior when subjected to a buried nuclear blast. A knowledge of rock behavior under impact was used to evaluate the materials of the moon by means of the geometric configurations visible in the close-up pictures of the moon surface taken by the U.S. rocket Ranger 7. The composition of the moon must be considered in devising methods for taking samples of the surface layers or in designing underground shelters as bases for future explorations of the moon.

Jan 1, 1965

Although the Stamler feeder/breaker has been used for coal crushing in underground mines for many years, it has only recently been applied to other crushing operations. Two companies presently using Stamler feeder/breakers for rock crushing were contacted regarding their experiences with the units in actual field use. In both cases information was obtained directly from the individuals responsible for field operation and maintenance of the units. White Pine Copper Co. has been using Stamler feeder/breakers for over two years to crush copper ore. They now have fourteen 450-ton-per-hour units on line. The ore has a compressive strength of from 18,000 to 28,000 psi and is extremely abrasive. Maintenance is performed on a tonnage basis. The breaker shaft is replaced every 250,000 tons (requiring about 4 hrs) and picks are replaced about every 1500 tons by the operator (requiring about 2 min per pick). Very little unscheduled maintenance has been required. Crushing costs are fairly high (estimated at 13 to 15t per ton including maintenance and operation) because of tale extreme abrasiveness of the material. A new Stamler feeder/breaker with Ultramet wear surfaces was put or line in June 1976. Ultramet was found to increase the life of belt transfer station surfaces by up to 400 percent and it is hoped that it will do the same for the feeder/breaker. At this time it is still too early to evaluate the performance of the Ultramet unit. If it does improve abrasion resistance, crushing costs could be greatly reduced. White Pine is very pleased with the units and the service provided by Stamler.

Jan 1, 1976

By J. H. Perry, Joseph Cervik, G. N. Aul

The Bureau of Mines is conducting research to determine the effectiveness of long holes in degasifying an area of the Upper Split of the Lower Sunnyside coalbed at Kaiser Steel CO.&apos;s Sunnyside No. 1 mine. These holes were drilled from the two outside entries of a section that was closed to mining because of excessive methane emissions. Two holes drilled to 430 and 450 feet produced initial gas flows of 160,000 and 127,000 cfd, respectively. Sixteen days after the completion of the second hole, the total gas production declined to just over 144,000 cfd. In 9 months of degasification, over 35 MMcf of commercial-quality gas has been removed from the coalbed. The combined gas flows declined to 106,000 cfd in the 9-month period. The two holes have reduced face emissions by about 40 pct.

Jan 1, 1978

By D. L. Boreck

Thick coal seams are common in the Western United States, Many seams are over 50 it thick (some are over 200 ft thick) and are too deep to extract using surface methods. Currently, such deposits are developed using standard "eastern" mining methods which only extract a few feet of total seam thickness, often rendering the remaining coal unminable with current technology. Novel methods that increase thick-seam recovery have been developed and are currently being used in Europe. These methods--high-face single-pass and multislice longwall, longwall caving, and hydraulic mining--have great potential for use in the United States. Successful use of these methods is an objective of the Bureau of Mines. Their use requires, among other things, a full evaluation of geologic features common to thick coals. The objective of this report is to present and summarize those features that will affect the introduction of the methods into thick-seam mines in the Western United States. The geologic elements delineated are three-dimensional configuration of the seam, cleat development, joints and fractures, roof and floor lithology, and faulting.

Jan 1, 1986

By D. Harrington

The occurrence of dusts in underground workings creates many difficult and, in some instances, contradictory and conflicting problems for workers, operators, and all others interested in health and safety in mining and tunneling. Moreover, there are many misconceptions both as to the actual effect of most dusts which may be encountered in underground work and as to remedial or alleviating measures. Although the harmfulness of mine dusts to health of miners has been mentioned by man; writers in ancient times, much of our really authentic knowledge of the effect of underground dusts upon health or safety in both coal and metal mines has been pained during the past 30 or 35 years. There has been, however, a considerable amount of generalizing from some local condition or occurrence or theory rather than arriving at conclusions after extended studies and observations made not only in mines and tunnels but also in town, camps, and plants, and comprising date on as many different mining and tunneling localities, conditions, etc., as could be secured with reasonable expenditure of time or money. This paper dives sortie observations based on the writer&apos;s 30 odd years of experience in and around both coal and metal mines, including approximately 20 years? close study of dust disease with detailed surveys and reports on dust occurrence and effects in considerably more than 100 mines in probably 20 States of the Union. The observatio are those of an engineer and in many respects conflict the with "going" ideas of doctors, pathologists, and others who have written on dust disease. Were the word dust is used in this p: per in connection with respiratory disease, it refers to solid particles which float or can float in the air breathed by workers. Although these particles are usually dry, they may be wet; in general, their dimensions are so small as to be invisible to the nailed eye. Dusts in coal mines which may be involved in the initiation or extension of explosions, are generally thought to be those which are smaller than 20-mesh in size but chiefly finer than 20-mesh; coal-mine dusts which are harmful to health of workers have essentially the same general physical characteristics as other dusts, but usually consist of smaller particles.

Jan 1, 1936

By N. E. Hanna

The effect of small percentages of sodium chloride on the incendivity of permissible explosives was studied by the Bruceton up-and-down technique in gallery tests. Both the reduction in incendivity achieved by addition of sodium chloride and application of the test method to explosives evaluation are discussed. It is demonstrated that the up-and-down technique in gallery testing is suitable for distinguishing differences in incendivity between different explosive compositions and between lots of the same composition. The study also shows that addition of relatively small quantities of sodium chloride tends to reduce the incendivity of explosives to firedamp, but addition of sodium chloride cannot insure reduced incendivity. Any improvement attributable to the salt can be counteracted by undefined variations in the explosive. The need for experimental investigations of a number of factors that may affect the safety of permissible explosives is emphasized. ACKNOWLEDGMENTS Grateful acknowledgment is made of the assistance of Roy L. Grant in analyzing for normality of distribution of the data obtained by the up-and-down methods and to Harold E. Tubbs for numerous calculations.

Jan 1, 1959

By J. Roger Loebenstein

Small amounts of arsenic trioxide were shipped in 1988 from remaining stocks at ASARCO Incorporated&apos;s closed plant at Tacoma, WA. Imports of arsenic trioxide were at about the same level in 1988 as in the previous year. Legislation and Government Programs The Occupational Safety and Health Administration (OSHA) levied a $1.6 million fine against Asarco for exposing its workers at its East Helena lead smelter in Helena, MT, to unacceptably high levels of lead and arsenic. The bulk of the fine was for violations of a respiratory protection program. The same smelter and its environs has been listed as a Superfund toxic-waste site by the Environmental Protection Agency (EPA). Tests had shown high levels of lead, cadmium, and arsenic in the soil near the smelter. EPA planned to extend the cleanup to areas within the town of East Helena because high levels of arsenic had been found in shallow test wells outside the smelter site. Federal and State health officials have warned residents living in the vicinity of East Helena to avoid eating certain home-grown vegetables because of high concentrations of heavy metals.2

Jan 1, 1990

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

8. Field Demonstration of the Remote Mine Sealing System in a Coal Mine 8. 1 Selection of Field Test Site Eastern Associated Coal Corporation (EACC) offered its Federal No. 1 coal mine in Grant Town, West Virginia as the site for field testing of the remote sealing system. The choice of Federal No. 1 mine was particularly appropriate as the first attempt at fire control by remote sealing was done in this mine in 1963. EACC provided the men and equipment required for much of the initial preparation. Considerable assistance, advice, and background on coal mining technology was given by Mr. William Laird, Vice President for Research and Development, EACC, and by Mr. Lawrence Jackson, Resident Engineer at the Federal No. 1 mine. District 3 USBM office, the West Virginia Bureau of Mines, the Technical Support Group of the USBM, and Local 4047 of the United Mine Workers of America also cooperated. 8.2 Preparation of Field Test Site 8.2. 1 Underground Site Preparation The underground site chosen for the field testing was in a non-working portion of the mine within a few hundred feet of the main haulage road, as shown in Figure 80. Known as "Seven Switch, " this area was a 20 minute walk or 5 minute "jeep" trip from the man-trip shaft. Ten years having passed since this area was actively worked, considerable effort was required for gob clearing, roof bolting, rock dusting, and rejuvenating the track from the haulage road to the test area. Three primary borehole locations were chosen for the test program. Borehole No. 1 was in a straight passageway

Jan 1, 1973

By H. Billmayer

This report covers the period from June 17, 1974 to February 20, 1975, and describes the work performed in compliance with the requirements of Contract No. H0346102 and Modification No. 1 thereto. The purpose of the contract was to design protective canopies for an Elkhorn Scoop, a Lee Norse Miner, a Wilcox Miner and a Wilcox Bolter; to construct mockups of the canopies; and to obtain machine operator evaluations of the canopy designs by assessing the mockups while installed on their machines in the mines. The overall program objective was to achieve protective canopy designs for the four machines which would be acceptable to the operators.

Jan 1, 1975

By J. P. Baur

The sensitivity of radiochemical techniques makes possible the study of the initial-stage sulfuric acid leaching kinetics of chalcopyrite and other copper sulfide minerals. This Bureau of Mines study of the initial leaching of chalcopyrite used techniques to evaluate the molecular and electrochemical processes. High-grade Transvaal chalcopyrite was neutron-irradiated in a TRIGA reactor4 to produce radioisotopes copper-64, iron-59, and sulfur-35. Dissolution rates were measured in the time interval zero to 60 minutes, during which time significant anomalies were observed. First was an initial period of rapid dissolution lasting a few minutes; second, an arrest or ?plateau? region usually lasting from 6 to 10 minutes; third, a second period of dissolution of lesser rate than the first. The effects of solution variables such as pH, oxygen partial pressure, and ferric ion concentration at different temperatures were measured.

Jan 1, 1974