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By John W. Colburn

A tractor-integrated version of an explosive ripping system was developed for mining application. This system utilizes diesel fuel and a tractor-mounted blower supplying 30 psig compressed air to a two-stage combustion chamber to produce a high pressure (600 psia) gas charge. The charge is rapidly released into the rock formation near the tip of the ripper. The system, mounted on a D9 tractor, was tested at several quarry and mining operations to investigate rock fracturing effectiveness. Although the results of comparative ripping passes conclusively demonstrated that the system increases rock fracture, performance of the system is strongly dependent on rock morphology and properties as well as basic performance of the tractor-ripper. The theory of conventional and explosive ripping modes is described and existing correlations of seismic velocity and ripper performance are shown to be in error.

Jan 1, 1977

By J. H. Crary

This report summarizes the results of a one-year agreement for research on the electromagnetic environment in coal mines, which was conceived as the beginning of a long term cooperative program between ITS and the Bureau of Mines. The concepts on which it was originally based are a result of the report on mine rescue and survival by the Committee on Mine Rescue and Survival Techniques of the National Academy of Engineering, dated March 1970. This report drew particular attention to the need for improved communications during and following mine disasters. In particular, the outstanding problems identified were the location of, and communication with, trapped miners. Some tentative solutions, generally involving long-wave electromagnetic signals, were offered. Consideration of the problems of disaster location and communication soon leads to consideration of the communications techniques (or lack of them) for use under normal mining conditions. In particular, if a disaster communication and/or location system is to be readily available and operable under disaster conditions, it should also be usable during mining operations. In this way operators can become familiar enough with the system to operate it during disaster conditions, as well as provide a mechanism for regular testing.

Jan 1, 1972

By Leonard Obert

Subsidence to surface occurs in a large proportion of underground mines. Preliminary to any indication of subsidence on the surface, there is usually a breaking up and sloughing of the cover into the mine opening which, in a period of time ranging from minutes to many years, progresses to the surface, This process is referred to as subsurface subsidence. In many mining operations, information regarding the process of subsurface subsidence is important, For example, if there are buildings or other improvements on the surface, or if the direction of the subsurface subsidence might threaten other underground workings--such as shafts--or if the subsidence might be progressing in a direction which would fall outside the anticipated subsidence limits, the problem could assume special significance.

Jan 1, 1961

By John A. Organiscak

Laboratory and underground studies were conducted by the Bureau of Mines to evaluate the effectiveness of a water-powered scrubber and a brattice partition to create a clean split of air for longwall workers at the tailgate. In simulated laboratory tests, the system was very effective in creating a clean split of air. Observed system efficiencies were 74 and 84 pct with induced airflows of approximately 2,000 and 2,500 cfm, respectively. Underground evaluations indicated that the system was capable of reducing respirable dust at the tailgate. The first underground evaluation resulted in protection efficiencies of 30.7 and 42.5 pct at scrubber water pressures of 150 and 450 psig, respectively. A 33.7-pct protection efficiency was observed in the second underground evaluation with a modified partition and the scrubber operating at 250-psig water pressure. To be most effective, the system should have the scrubber operating at a flowrate of 10 gpm at 500 psig to deliver a maximum quantity of cleaned air behind a well-sealed partition.

Jan 1, 1983

By M. R. Geer

Full-seam mining with continuous mining machines in dirty coal beds may increase loss of coal in the washery refuse. At one mine mentioned in this report the loss of salable coal was increased sixfold. Cleaning trials were made on three samples of jig refuse in a dense-medium pilot plant to demonstrate the application of this process to the recovery of coal from waste. These tests demonstrated that coal could be separated from impurity with the same degree of sharpness obtained in treating raw coal by dense medium. However, the recovery efficiency achieved in treating refuse averaged distinctly lower than that possible with raw coal because of the greater proportion of intermediate-density material in the feed and the lower yield of clean coal.

Jan 1, 1955

By Ronald A. Munson

Samples of the naturally occurring zeolites phillipsite, clinoptilolite, erionite, and chabazite have been surveyed for their gas adsorption, ion exchange, and other characteristics. Chabazite and erionite, which are generally more stable, also have higher methane adsorption capacities than do the other natural zeolites. Both natural erionite and natural chabazite are classified as small-port zeolites on the basis of their inability to adsorb chlorotrifluoromethane. In the range of 8 to 100 mesh, the adsorptive capac-ity of natural zeolites is improved only slightly by a decrease in particle size. The capacity of natural clinoptilolite to adsorb methane is increased by cation replacement by the hydrogen ion and decreased by exchange with calcium ion. Natural phillipsite, which is easily decomposed by heat, adsorbed methane to a limited extent.

Jan 1, 1973

By L. Mark Irwin, R. A. Marsyla

The objective of this laboratory investigation was to develop a mattesmelting process for the recovery of copper from industrial smelter dusts . Experimentation was conducted on three samples of Cottrell precipitator dust from a northern Michigan smelter with variations in the following conditions : Temperature , charge composition , pelletization , and moisture content . Based on chemical analyses of the furnace slags , poorest recovery of copper was effected in smelting dry charges regardless of composition . Some improvement was noted with uniformly moistened charges and still more with pelletized (but dry) mixes , but best results were obtained from smelting moist , self - fluxing pellets . Under favorable conditions , experiments yielded furnace slags with an average copper content of only 0.15 percent , which is well below that of industrial copper reverberatory slags .

Jan 1, 1963

By Allen D. Look

Use of two-way radio communication at the Santa Rita open pit of the Kennecott Copper Corp. has furnished a satisfactory answer to the problem of communications for an operation covering an extended area. Coordination of operations has resulted, with little loss of time in making changes during the shift. Repairs are facilitated, and safety of operations is increased through better control of blasting and hazardous conditions. INTRODUCTION Expansion of mining operations brings increasing needs of improved communications to coordinate the mechanized operations that contribute to the efficiency of present-day open-pit methods. Equipment found satisfactory when first installed becomes inadequate as distances and demands increase. It is the, purpose of this paper to record the progress being made by one mine in meeting this problem.

Jan 1, 1952

By J. W. Adams

This report surveys the efforts of six contractors to the U.S. Bureau of Mines with regard to their electromagnetic noise measurement programs. What has been done, what is planned, and evaluations and recommendations are given for each contractor. The main observation is that to date there is not sufficient knowledge of electromagnetic interference in mine environments to design a reliable communication system. This knowledge should be available by the end of June 1972 if certain planned programs are completed successfully. A major effort of this report is to establish parameters to be measured, units to be used, and workable formats for data presentation. This is given in Appendix A. Some details concerning equipment, procedures, locations, and sample data are included in Appendix B.

Jan 1, 1971

By D. Harrington

Correct ventilation of underground workings whether in coal or in metal mines consists in establishing such control of air currents that the miners may work in safety, with maximum comfort and efficiency, and without impairment of health; also in controlling the air flow so that the mine workings may at ordinary times be kept reasonably free of harmful gases or dusts, and so that in time of emergency, as when a fire or an explosion occurs, there may with minimum delay be maintained as much or as little air flow as is desired throughout the mine in its entirety or in certain parts of the mine. Control of air flow is the essential point of any mine ventilating system, and is obtained only by the installation of mechanically operated fans, and other ventilating devices such as doors; overcasts, regulators, etc. Every mine, large or small, coal or metal, should from the outset be equipped with a fan. Much has been written about natural ventilation, and many claims have been made that in specific mines or parts of mines there is sufficient natural air flow. As a matter of fact, there are actually very few if any mines, coal or metal, where natural ventilation creates atmospheres anything like adequately safe or healthful for underground workers even at ordinary times or under ordinary. conditions; and at the time of a fire or an explosion mines depending upon natural ventilation are practically helpless, and are decidedly dangerous for the unfortunates forced to be in them either at the time of the disaster or afterwards when trying to handle conditions arising from the emergency.

Jan 1, 1929

"Status of the Mineral Industries" provides a written and graphic view of the Nation's mineral position and its mineral industries. The report, issued annually by the Bureau of Mines, U.S. Department of the Interior, describes recent activities in mineral production, consumption, imports, exports, and uses of significant minerals and mineral raw materials. Charts profile trends for the past 28 years in supplies and uses of iron, steel, major nonferrous metals, primary nonmetallic construction raw materials, fertilizers, and plastics. Also included are current and historical financial data on the mineral industries, such as debt-equity ratios, asset-to-liability ratios, and plant and equipment expenditures.

Jan 1, 1979

By K. C. Dean

Changes in the types of materials used for the construction of recent automobile models have occasioned a review of the continued applicability of current recycling techniques. Plastics are being used increasingly in late model cars. To evaluate the changes occurring, a 1972 Mercury Montego, furnished by the Ford Motor Co., was completely dismantled and analyzed, and the composition was compared with that of a composite automobile from 15 vehicles ranging in date of manufacture from 1954 to 1965 and designated as a circa 1960 model. The composite vehicle contained about 26 pounds of plastics, while the 1972 model contained over four times that quantity. The increasing use of plastics in automobiles suggests that research to improve the economic potentiality of plastics recycling is warranted.

Jan 1, 1974

By H. S. Hardman, G. T. Adams, Will H. Goghill

"Usually a newly developed machine leaves the factory ""on a wing and a prayer."" The manufacturer hopes that the operator will hasten to report defects. In turn, when the suggestions arrive the manufacturer makes the required changes and maintains close collaboration with the operator. Thus the history of our machines of today is written.Laboratory concentration tables are exceptions to growth by experiment and collaboration. Their operation never enters directly into the cost sheet; they are seldom used for longer periods than 10 minutes; and the experimenter, while hurrying to another job, accepts the table, good or bad, for a quick test on his ore. Thus we go back about 50 years when we use the preset in factory-built laboratory table.The Southern Experiment Station, Bureau of Mines, in cooperation with the University of Alabama, recognized the existence of a tabling problem net usually considered. That is, instead of using the table to test the ore, the ore was used to test the table. In this critical examination of laboratory table six defects were encountered (and remedied). They are:"

Oct 1, 1945

By J. Bootle

Marrow vein deposits will continue to be an important source of valuable minerals. Productivity per manshift is not keeping pace with operating costs. Increased mechanization of stoping operations must be obtained to create greater productivity at a reduced cost per ton. This application of mechanization may be to either present methods or to newly developed concepts. The total mine unit operations will be effected by increased productivity. Two approaches to increasing the mechanization of narrow vein stoping were studied with the intention of increasing stope productivity and decreasing stoping costs. A method of bringing efficient rubber-tired equipment into narrow cut and fill stopes was designed. It proposes to provide stope access by way of a ramp constructed on the stope fill. Impact breaking equipment was studied and specific applications proposed.

Jan 1, 1977

By D. W. Frommer

The investigation reported in this paper is one of several included in a broad program of developing new or improved concentration processes for the oxidized and partly oxidized deposits of lead and zinc, A sample from the Playter lease, Newton County, Mo., containing pyromorphite was successfully concentrated by fatty acid flotation to a grade of over 62 percent lead. Owing to the presence of a high content of slime-size values, the overall recovery of lead at that grade was limited to 44 percent. DESCRIPTION AND HISTORY OF PROPERTY The mineral pyromorphite is a chlorophosphate of lead containing 76.4 percent lead, and, although it occurs frequently in association with other lead minerals, it is considered a minor ore mineral of lead. The manner of occurrence of oxidized lead minerals, including pyromorphite, which frequently are no larger in grain size than the clay with which they are found, militates both against development of a simple beneficiation process and high recovery. The profitable exploitation of such deposits depends not only on a successful treatment procedure but a highly favorable metal market as well. For these, and perhaps other reasons, very little research has been done on the recovery of pyromorphite from its deposits.

Jan 1, 1956

By John A. Davis, David W. Brunton

During the past few years great progress has been made in the United States toward safer, more efficient, and more economical tunneling methods. This advance is partly due, no doubt, to the recent increase in the number of tunnels and adits driven for devel- oping and draining mines and transporting ore. The Bureau of Mines during 1911 and 1912 made a special examination of this phase of mining operations, in connection with an investigation of mining methods and means for preventing accidents. The details especially studied were the provisions for the safety of employees, the kinds of equipment, the methods of driving, and the costs of con- struction. The results and conclusions obtained from that investi- gation are discussed and summarized in this bulletin. Up-to-date information concerning tunneling methods is difficult to obtain. There are few books on the subject; and much of the material they contain, although interesting and of value historically, is now obsolete. The engineering periodicals, it is true, endeavor to keep abreast of the times, and several in nearly every issue present some article bearing upon tunnel work. But the very multiplicity of these articles prevents one from reading them all, and the foreman or superintendent in charge of a tunnel, or the mining engineer designing one, and especially the business man financing the project, has no time for a lengthy search after scattered articles in order to determine the present status of tunnel work. Then, too, knowledge of new methods travels slowly. Valuable inventions and improve- ments in tunneling as well as in all the other industries frequently remain in the notebook of the investigator, or as theses are buried in university libraries, or are published only in journals of small scien- tific societies. New tunneling methods and equipment that are prov- ing safe, efficient, and economical may be totally unknown outside the district in which they originate. This paper, based on a special examination both in the field and in engineering literature, is in- tended to supply data concerning modern and recent tunneling practice in the United States, and to make suggestions that, it is hoped, will result in a saving to the mining industry of energy, capital, and life.

Jan 1, 1916

By Richard Rittenhouse

This program was to develop a new base line system for automated continuous room and pillar type mining. The primary requirement estab¬lished for this machine is that the machine be capable of mining and bolting simultaneously. Additionally, this machine was to provide temporary and permanent roof control, have a productive - full - face semi-automatic mining system, leave a clean entry outby the machine, provide maximum operator protection, provide effective dust suppression and provide air scrubbing to restrict respirable dust to permissible levels. The machine has effectively demonstrated the ability to mine and bolt simultaneously. Additional above ground operation, testing, and time studies are recommended to further verify the machines abilities. Design improvements are recommended for future generation AES machines. These relate to marginal design areas such as side loading on vent duct lift cylinders, etc., that will not impair additional testing of the existing machine.

Jan 1, 1983

By Frederick W. Horton

The lack of comparable and accurate statistics of coal-mine accidents in the United States as a whole led the Bureau of Mines in 1911 to undertake the collection of such data. The importance of such statistics as a basis for remedial legislation can not be overestimated, moreover they serve to indicate the results of the efforts made by the Federal Government, State mining departments, and mine operators throughout the country to lessen the hazard of coal mining. The mining departments of the leading foreign coal-producing countries have long taken cognizance of the importance of such statistics. In Great Britain, official statistics of coal-mine accidents have been collected and published since 1851, in France since 1853, in Austria since 1875, in Germany since 1852, and in Belgium since 1831. The United States not only leads these countries in the production of coal but the output of its coal mines is greater than those of Great Britain, France, Belgium, Austria, India, Japan, and New South Wales combined. Accordingly, it is proper that there should be some official record of the accidents in this, the greatest mining industry not only in the United States but in the world. It is especially appropriate that this work should have been undertaken by the Bureau of Mines, as, through its investigations of mine accidents in the field, it is constantly in close touch with coalmining conditions throughout the country. Its engineers are not only able to obtain first-hand information as to a great many accidents, but, through their special training and experience, are able to appreciate the significance of the figures reported by the coal-mine operators, thus aiding an intelligent and uniform classification 01 the accidents for the country as a whole. Further, the State mining dnpartments and State mine inspectors of every State in the country having a system of coal-mine inspection are cooperating with the bureau by sending it monthly reports of accidents in the coal mines of their respective States. The receipt of such reports places the bureau in a most advantageous position to publish promptly statistics of these accidents. Although a few years ago accurate statistics of c~al-mine accidents in the United States as a whole were entirely lacking this bureau was able to pubjiish the 1912 statistics within three n:onths after the close of the year and long before corresponding statistics had been issued by the mining departments of the leading foreign coal-producing countries. The cooperative agreement with the State coal-mine inspectors has not only made possible the prompt publication of the statistics, but it has also enabled the bureau to classify the fatalities by months and according to cause, showing the months in which the greatest and the least number of men were killed and from what causessomething that has never before been accomplished for this country.

Jan 1, 1913

By Doris M. Hyde

In the past, mining has represented between 11% and 12% of the gross domestic product (GDP). In 1982, mining contributed over $150 million to the estimated $1.4 billion GDP.2 Overall economic growth for 1983 was projected at about 2%, primarily as a result of increased tourism. The inflation rate remained at or fell below the 1982 level of almost 4%. The Government continued its efforts to strengthen the industrial base by improving infrastructural systems and the establishment of a free trade zone. Laws against property ownership by foreigners or foreign-owned companies were strengthened, but the prohibition was softened to allow for close family inheritance. Otherwise, Government approval must be obtained to retain property acquired through inheritance, court order, mortgage, or other means. Special consideration was granted to foreign investors seeking to promote industries beneficial to the economy.

Jan 1, 1985

By T. M. Barczak

One of the primary goals of Bureau of Mines research is to reduce the cost of coal mining by improving the efficiency of longwall supports. One method of achieving this goal is the optimization of stress distribution within the support structure, resulting in a lower overall weight, more fully stressed shield. However, before stress optimization can be initiated, load conditions must be defined that cause maximum stress in the various support components. A finite-element model of a longwall shield was used to identify these critical load conditions. These load conditions were then evaluated in the Bureau's mine roof simulator (MRS) by instrumentation of a longwall shield and measurement of strains in each of the shield components. The critical (canopy-base contact) load conditions were identified that can cause structural failure at less than rated shield (hydraulic yield) capacity. Comparisons were made between full-contact and partial-contact load conditions. Other parameters investigated included the stiffness of the contact material, changes in shield geometry, rate of load application, and effects of horizontal constraint. Conclusions were drawn regarding the structural integrity of the major shield components and potential for stress optimization.

Jan 1, 1987