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Throughout October, U.S. producers priced unalloyed 99.5 percent aluminum ingot at 53¢ per pound. Dealers, in last month's domestic market, were quoting unalloyed ingot at a range of 45.5¢-46.3¢ per pound. Costa Rica recently issued a proposal to Japanese aluminum smelters to participate in an integrated aluminum-refining project which would include bauxite development. The project reportedly would include a 600,000-kilowatt hydroelectric power station, a 600,000-metric-ton-per-year alumina plant, and a 300,000-ton-per-year primary aluminum smelter. Two U.S. firms--Aluminum Co. of Amerjca (Alcoa) and Martin Marietta Co.--and several European aluminum smelters are also said to be interested in taking part in this project. Alcoa conducted a feasibility study for the Costa Rican Government in 1970 and estimated the bauxite reserves to contain 150 million metric tons.

Jan 1, 1977

By Julius G. Chang

Against the receding background of the October stock market crash and the December overhang of inventories, the economy began with a shaky start in 1988. As 1988 began, the Administration's estimate of real growth for 1988 had just been reduced from 3.5% to 2.4% and economists and other ob-servers were concerned that the expansion that was 5 years old might be near the end and that a recession might be around the corner. The ensuing moderately strong economic activity, however, belied all the negative signals that were evident earlier, and the real GNP continued to grow at an estimated 2.3% annual rate during the first quarter of 1988, extending the ongoing recovery into the sixth year (table 1.). The relatively accommodative policy of the Federal Reserve Board (the discount rate was cut by 0.25% in January), a strong performance by the export sector, and the revival of consumer spending were major forces underlying the economic strength. But as the quarter drew to a close, signs of tight capacity utilizations were apparent in many of the export and capital goods sectors, including textile, chemical, plastic, metal, and machinery. Employment was at a record high level while the unemployment rate was close to a historical low. Prices were rising at a faster pace than those of 1987, and the dollar resumed its slide after a brief recovery in January and February. These factors gave rise to the fears of higher inflation. Long-term interest rates increased, casting a pall over the prospect of a robust growth for the rest of the year.

Jan 1, 1988

By G. E. McElroy

Tae purpose of this paper is to present types of charts adapted to aid in the graphic solution of fan-performance problems of selection and operation, and to urge the adoption of similar charts by the National Association of Fan Manufacturers as standard forms for presenting fan-performance data. As matters now stand, it is difficult for the average engineer to solve such problems because a laree number of variables are involved, and performance data are not presented in a manner that permits their direct application to many problems encountered in practice. The performance of any centrifugal machine is determined not only by the machine itself but also by the fluid-flow system on which it operates. Actual performance of centrifugal fans is therefore e matter of the type, size, and speed of fan, on the one hand, and of the relation of pressure to quantity of flow, as determined by the physical condition of the airway system, on the other.

Jan 1, 1936

By P. C. McWilliams

Researchers at the U.S. Bureau of Mines investigated the use of close-range photogrammetry and subsequent stereo digitizing to obtain data from rock fracture roughness profiles. The photogrammetric process yielded results that were acceptable but somewhat inferior to those obtained by a mechanical profilometer. On the basis of this study, further pursuit of photogrammetry as a data collection method in mining is proposed. Fractal geometry was investigated as a means of measuring the roughness of rock fracture profiles. Four fractal algorithms were used: divider method, modified divider method, box method, and spectral method. A comparison of the methods gave ambiguous results. Brown's modified divider method provided the best means of obtaining the fractal dimension. Shear strength estimates were obtained using the parameters of the modified divider method and Myers' Z2 measure. Because of differences in results when comparing the different ways of obtaining the fractal dimension, future users of fractals in studies of rock fractures are advised to cross-check their results carefully.

Jan 1, 2010

By G. E. McElroy

[The purpose of this paper is to present type: of charts adapted to aid in the graphic solution of fan-performance problems of selection and operation, and to urge the adoption of similar charts by the National Association of Fan Manufactures as standard forms for presenting fan-performance data. As matters now stand, it is difficult for the average engineer to solve such problems because a large number of variables are involved, and performance data are not presented in a manner that permits their direct application to many problems encountered in practice. The performance of any centrifugal machine is determined not only by the machine itself but also by the fluid-flow system on which it operates. Actual performance of centrifugal fans is therefore a matter of the type, size, and speed of fan, on the one hand, anti of the relation of pressure to quantity of flow, as determined by the physical condition of the airway s: stem, on the other.]

Jan 1, 1936

By M. R. Geer

This report presents the results of washability examinations of seven coals from the principal coal-producing fields of Montana. A complete performance test of the Baum-type jig operated at one of the mines is included, as are the results of cleaning tests made on two of the coals in a dense-medium pilot plant. The coals examined from the Red Lodge, Bull Mountain, and Forsyth fields are comparatively easy to clean. Ash contents of 5 to 10 percent can be obtained at yields of washed coal ranging from 90 to 95 percent. The coal from the Great Falls field, however, could not be cleaned readily to less than 14 percent ash, and the rejection of impurity would amount to over 25 percent. The two coals treated in the dense-medium pilot plant were characterized by sharp separation of impurity, high recovery efficiency, and satisfactory reduction in ash content.

Jan 1, 1955

By Bertha R. Klahold

"In response to numerous inquiries regarding tests and analyses of minerals and related inorganic materials; Bureau of Mines Information Circular 6999, ""Laboratories That Make Fire Assays, Analyses, and Tests on Ores, Minerals, Metals and Other Inorganic Substances,"" by C. W. Davis and M. W. von Bernewitz, was published .in 1938 and revised in 1939 (I. C. 6999R). In this paper on analytical and testing laboratories, the original text has been rewritten and expanded, and a table has been added, in which are listed laboratories prepared to offer a number of special testing services in addition to ordinary assays and chemical analyses. The arrangement of laboratories on, a geographical basis has been maintained.This circular is compiled as a public service, and none of the laboratories listed herein is recommended over any other,These lists were compiled from questionnaires sent to organizations whose work is connected with mineral and metallurgical testing. The response in general was very satisfactory, and the author takes this opportunity to express her appreciation to the officers of the listed laboratories for their cooperation.Acknowledgment is also made of the valuable assistance of the members of the technical staff particularly Morris Slaving/ of the Eastern Experiment Station of the Bureau of Mines at College Park, Md., in the preparation of the questionnaire and technical descriptions.Many mineral samples are sent to government agencies in the National Capital with the request that they be assayed or chemically analyzed. It should be emphasized that there is no place in Washington D. C. where assays and quantitative analyses are made for the public b the Federal Government.Virtually all of the States maintain a bureau of mines, a geological survey, or some similar organization, frequently at the State University, where minerals found by residents of the State will be identified free of charge. Usually, a charge is made for assays. Specific tests, as on clays, are made by some of these offices.The Federal Bureau of Mines, although it attempts to avoid duplication of services rendered by State Bureaus, is always glad to give advice as to prospective markets. It does not compete with private assayers and chemists, but with respect to samples sent to its field laboratories, it does offer to identify them as far as this can be done by inspection and simple optical and chemical tests. This examination is usually sufficient to indicate whether the material has commercial value, or at least if the expense of an assay would be warranted. Except in connection with its own technical investigations, no assays or other special tests are made by the Bureau of Mines.The Federal Geological Survey and the National Museum also make simple tests of specimens as a public service. Neither of these bureaus nor the Bureau of Mines, however, can afford to render such services on long suites of specimens submitted by mineral dealers, well drillers, or others, when such work can be done regularly by commercial concerns."

Oct 1, 1949

By Gerhard Braüner

The report gives a review of the methods of predicting mine subsidence; these methods are used particularly in European coalfields. The methods are subdivided into two groups, based on mathematical expressions either for the trough profile or for the influence of infinitesimal extraction elements. The fundamental relationships common to all methods described herein are the principles of superposition and of equivalent extraction areas. The involved parameters are derived from field observations. For calculating horizontal displacements, their relation to the slope of the subsidence profile is applied. The time-dependent development of the subsidence process is characterized by the empirical "time factor." Modifications for the case of inclined strata are considered. A brief review of experimental and theoretical model investigations is given.

Jan 1, 1973

By K. K. Kelly

METALLURGICAL thermochemistry of titanium is a broad subject and (if data were available) could include a wide variety of topics. The present report is restricted to extractive metallurgy and to substances and reactions that bear upon the magnesium, sodium, and hydrogen-reduction processes employing titanium tetrachloride. The aim has been to present enough data so that the reader not only can check: the calculations for the reactions discussed but also can conduct related calculations if he so desires, without recourse to other compilations of data. The subject matter divides naturally into two parts-the selection of the data to be adopted and the application of these data to pertinent metallurgical reactions.

Jan 1, 1959

By S. J. Hemberger, F. W. Lee

"This project constitutes the results of a geophysical field investigation undertaken in the mining areas in the vicinity of Marion, Crittenden County, Kentucky.Results were obtained at well-known mines being worked for fluorspar. Of special interest was the determination of mineral trends at such mines, particularly in relation to the fault patterns, because of ore in them.This work also constitutes a comparison between the field information that can be obtained by purely geological means and the additional information obtained by applying geophysical surveys to the same areas.As the mineralization in this area is controlled almost surely by the faults therein, the great importance of locating faults cannot be over emphasized. Accordingly, there has been incorporated herein the analyses as well as the application of electrical resistivity methods for fault determinations.In the western part of Kentucky, particularly in that area designated as the Cave-In-Rock quadrangle by the United States Geological Survey, is located the center of the fluorspar mining district of Kentucky. From the mining as well as commercial viewpoint, this area is of considerable interest and importance. It has been described by Currier4/ as a large structural dome that collapsed, through faulting, into a mosaic composed of a main fault pattern that has a strike to the northeast in sedimentary formations. Accompanying this main fault pattern are a large number of irregular faults. This fault complex is also traversed by a dike pattern that has a regional strike for this region focusing a northwesterly direction. The faulting occurred before the dike intrusions, the latter being composed largely of peridotite rocks. According to Reed,5/ most of the metallic mineralization, composed chiefly of galena and sphalerite, occurs at or near the Intersection of the dikes with the faults, indicating a possible igneous origin of the ore deposits. Reed adds that the fluorspar generally does not follow this rule but may also be found in other portions of the faulted zone not directly related to dike intrusions. The area may be considered of equal interest in the occurrence of lead and zinc and in the occurrence of fluorspar controlled by the faults. Hatmaker and Davis6/ give detailed information concerning the form of the ore bodies and economic factors that control ore production in this area; they also suggest the application of geophysical methods in this territory. Ulrich and Smith7/ also discuss geological details in this area. This area is therefore of interest, whether examined from a large structural point of view or from a very detailed angle. The former will assist in determining the origin of the mineralization and its economic possibilities, whereas the latter will give details concerning fault locations and their geologically and geophysically controlling features. This work was undertaken as a pilot investigation relating to the study of the location of fault occurrences, in which it was attempted to determine the location of faults as well as the fault patterns in certain isolated areas. No effort was made to identify the mineralization from the gouge material in the faulted zones; this problem was left for subsequent investigations."

Jun 1, 1946

By L. G. Austin

The model originally proposed by Austin, et al., has been modified in the light of further investigation of the breakage laws in SAG milling. The model uses a fully-mixed reactor for short L/D mills and calculates the breakage of small particles by the nipping action of balls and pebbles. The autogenous self-breakage of larger lumps is treated as an effective means of fast breaking rock and much slower breaking rock. Experiments show that fast autogenous breakage can be treated as a first-order breakage with an overall specific breakage rate which incorporates fracture and chipping. Similarly, slow breakage incorporates fracture and abrasion. Autogenous breakage is cushioned by the accumulation of fine material. Simulation results are compared to results from tests in a 2 m diameter continuous pilot-scale SAG mill. Future work is discussed.

Jan 1, 1985

Past issues of Minerals and Materials have discussed such aspects of the economy as consumption and investment expenditures, interest rates, productivity, and international trade barriers and their effect on the minerals industry here and abroad. In this issue, we will (l) look at recent indications of a possible economic recovery, (2) present 1983 expectations reflecting the results of industry surveys conducted by the U.S. Department of Commerce (DOC), and (3) briefly discuss the contribution of the U.S. mining industry to total gross national product (GNP). THE RECOVERY Throughout most of 1982, DOC's Composite Index of Leading Indicators provided evidence of impending improvement in the economy. The index increased moderately during eight of the months in 1982 and then jumped an estimated 3.6 percent in January 1983 (table 1). While the leading indicators continued to predict improvement, the general economy, as measured by the Index of Industrial Production, continued its slide through November 1982 (table 2). Finally total industrial production increased in December 1982 and continued on an upward path in January and February, as predicted by the leading indicators.

Jan 1, 1983

By K. K. Kelley

Despite the wide interest in titanium and its compounds, no heat and free-energy-of-formation values for titanates (that is, compounds formed from titania and other metal oxides) have been available heretofore except for ilmenite (FeTi03). Such data are needed for understanding and developing processes for producing titania and titanium tetrachloride from ores (and possibly slags) and in connection with ceramic usage of titania. This paper reports experimental measurements of the heats of formation at ordinary temperature of 11 titanates-ilmenite, perovskite, barium metatinate, strontium metatitanate, barium-strontium metatitanate, barium orthotitanate, strontium orthotitanate, barium-strontium othotitanate, geikielite, magnesium-titanium spinel, and magnesium dititanate. The experimental method was solution calorimetry. The solution calorimeter was operated at 73.7°C. and used a strong hydrofluoric-hydrochloric acid mixture as the calorimetric fluid and reaction medium.

Jan 1, 1954

By Matthew D. Meyer

SMART, an association of surface mining companies formed in 1995 to develop a coordinated approach to technology development for the mining industry, has recognized the need for the establishment of a worldwide database that continuously collects mining equipment data and provides metrics related to productivity and cost. Under the auspices of SMART, Syncrude Canada, Suncor Energy and Albian Sands Energy (three oil sands mining operations located in northern Alberta) have established a pilot project for mine benchmarking. This presentation will include a review of the pilot progress including: ???Data gathering techniques: means of collection and storage, proposed practice for data control and normalization, access to data/reports and format for data. ???Reports/analyses for individuals, across groups, within the total industry pool and publicly. ???Security and confidentiality of information belonging to identified parties. ???Sharing of best practices among members. SMART has identified two key deliverables to ensure success of the project. First, data supplied from surface mines must be validated and normalized to common definitions and then analyzed to provide participating companies with regular reports that allow them to understand their position and resultant opportunities to achieve world-class performance. This model maintains granularity of the data for each operation that can then be recombined into standard comparisons or specific indices as required. The general categories of: operating delays, maintenance downtime, standby, and scheduled downtime, have been used to frame comparisons. Second, participating companies are looking to go behind the indices to identify and share best practices that distinguish particular operations. The spirit of cooperation between the companies involved in the pilot project is meant to be a model for future expansion of the benchmarking project.

Apr 1, 2005

By P. R. Perry

This publication is a compilation of tested methods for the analyses of titanium tetrachloride, titanium sponge, and various intermediate materials and products. They are presented in concise form without the detail usually found in publication of new methods because many of them are modifications of well known procedures. The Electrometallurgical Experiment Station, Boulder City, Nev., has been developing titanium production methods since 1945. Most of this development was on a modified Kroll Process but also included work on sodium reduction and electrolytic methods. During these years a large variety of samples were analyzed. Most of the analytical problems were solved using published methods or modifications of the same. At the start, there were no published procedures for analyzing titanium sponge using spectrochemical methods. A great deal of study was given to testing several of the well known techniques, and some of them, such as direct sparking of the metal, proved to be completely unsatisfactory. Solution-spark techniques were finally tried, and satisfactory procedures were developed for some of the more common impurities. These spectrochemical methods were then put into routine use for several months before their publication.2/ Some new modifications have been made, and techniques have been developed to determine other impurities found in titanium sponge and tetrachloride. All spectrochemical methods used in 1954 are included in this publication.

Jan 1, 1955

By K. A. Natarajan

Platinum electrodes are not inert as originally thought to be. The reactivity of platinum electrodes can explain their erratic behavior in many electrochemical measurements of metallurgical interest, e.g., in flotation systems, streaming potential measurements, contact-angle measurements, and in leaching systems. The anomalous behavior of platinum electrodes in redox potential measurements in aqueous systems was studied through Eh and pH measurements in water-oxygen, iron-water-oxygen and manganese-water-oxygen systems. Stability relations between Fe++ and Fe(OH)3 and between Fe(OH)2 and Fe(OH)3 were studied to judge the correspondence between experimental and theoretical equilibrium lines. The practicality of redox potential measurements in estimating ferric-ferrous ratios in aqueous systems was investigated along with their suitability as indicators in leaching operations, e.g., the removal of iron by aeration from manganese leach solutions.

Jan 1, 1970

By Richard E. Chism

Jan 1, 1902

By Terry S. Cory

This report is a comprehensive summary of the results of the propagation measurements program conducted for the US Bureau of Mines under Contract H0366028. Data was gathered in the MF frequency range from a cross sample of six mines representative of the industry having typical wireless requirements. From the raw data which was gathered, a logical method of data reduction is presented which culminates in a set of average attenuation characteristics for all mines visited. These characteristics define a typical MF wireless system when the communication range requirements are known. Direct through-the-earth propagation and the range enhancement mechanism due to coupling on and off conductors are evaluated and related to the planning of a typical wireless MF communications system.

Jan 1, 1977

By R. G. Bradburn

The events which led to computer control of the grinding circuit at Brenda Mines are described, beginning with mill operating philosophy. High production rates are encouraged so that, despite severe upstream disturbances, a manual control method to meet this philosophy had developed. Unfortunately, due to the time interval between manual control adjustments, losses in production resulted. An analog control method was devised and, although superior to manual control in some situations, was found to suffer from several practical limitations. The data logging capabilities of a control computer seemed warranted. Circuit test- work combined with an analysis of operating data showed that (1) metallurgical personnel, at times could increase production rates by as much as 10 percent over that achieved by grinding operators, (2) the chosen data base required an increase of 2 percent or more to be statistically significant and (3) for a 2 percent increase there would be a significant rate of return of investment in a computer installation, Consequently one grinding circuit was fully instrumented, and a rented control computer was installed by Brenda personnel. Prior to installation, Brenda metallurgical and instrumentation personnel were trained in the use of the computer. An experimental program was devised with short and long term objectives. The short term objective was to develop a practical control strategy which would yield immediate production improvement. This goal has been met as described in this paper. Statistically significant increases in excess of 2 percent have been established. Work is being completed for the permanent installation of computer control on all four grinding circuits at the present time. Long term objectives are (1) off line analysis of the circuit using mathematical models of process units, (2) on line experiments to study alternative contol tactics, and (3) possible expansion of computer facilities to the crushing plant.

Jan 1, 1976

By M. F. Dunn

The objective of this work was to define jet fan performance in d variety of large cross-section underground mine applications and to develop guidelines for thin performance in open airways, dead headings, and multiple face areas. Measurements include common ventilation instruments, continuous recording remote electronic anemometers to measure air velocity, and sulfur hexaflouride tracer gas with chromatograph analysis to determine dilution rates and air recirculation. For open airways the following were determined: Large jet fans are leas efficient in smaller airways, but quite effective in larger open airways for achieving both uniformity end greater air entrainment, when inclined about 10° or elevated. For dead headings the following were determined: The jet fan must be placed against the rib of the heeding closest to the incoming airstream from the crosscut or recirculation will increase. The fan should be placed at the pillar corner to increase airflow. As the fan is moved closer inby, recirculation increases. Larger fans promote recirculation. Inclining fans about 12° improves airflow in large headings. For face areas the following were found: For panels having uncontrolled airflow, the fan should be placed in the incoming airflow, about one pillar inby, and directed diagonally across the faces. For panels having narrower rooms and controlled airflow, the fan should be placed alongside the panel side in the first room so as to direct or intersect the incoming airflow at the next entry or crosscut.

Jan 1, 1983