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By Oliver Bowles

From the most remote periods of civilization, stone Las been used to perpetuate the memory of individuals or to immortalize their noble achievements. Ancient memorials ranged from simple piles of stone (cairns) or single markers to great obelisks and pyramid or magnificent mausoleums. The Taj Mahal at Agra, India, built of white marble by Shah Jehan in memory of the Empress Mumtaz Mahal, is one of the most beautiful and costly memorials ever built. It was erected between 1632 and 1050 at a cost estimated at a: high as $50,000,000, and it is today an object of unusual attraction for travelers. Other magnificent memorials, both ancient and modern, are to be found in many lands. Memorials of varying design have characterized the passing centuries and have found an important place in the New World. In early days, monuments were chiefly imported into America, but gradually an extensive memorial stone-manufacturing industry developed on this side of the Atlantic. Sales value of domestic memorials, f.o.b. quarry or mill, attained a maximum of $17,488,755 in 1920, and retail sales, of course, reached a much higher figure. Modest markers and tombstones are to be found in almost every rural community in the United States, and there are many elaborate and costly monuments in and near urban centers.

Jan 1, 1938

By V. B. Dale

This paper is one of a Federal Bureau of Mines series covering the mineral resources of the Nation. It briefly describes most of the tungsten deposits in Cochise, Pima, and Santa Cruz Counties, Ariz. Most of the descriptions are from field examinations by the two senior writers, prior to July 1957. Wolframite first was identified in Arizona in 1896 by W. P. Blake, Territorial Geologist. Tungsten mining began about 1900 in the Little Dragoon deposits of Cochise County, and about 1901 in Las Guijas district of Pima County. The price history of tungsten is an erratic one; consequently, production has been erratic. Prices rise during wars and periods of national preparedness. Production of tungsten ore was stimulated greatly by a Government purchasing program, announced on May 10, 1951, wherein the Government agreed to purchase standard-grade tungsten concentrates at $63 per short ton unit5/ for 5 years or until 1,468,750 units were purchased. This was later increased to 3,000,000 units, and after this amount had been purchased in June 1956, the purchase of an additional 1,500,000 units was authorized. Government purchase, however, was suspended in December 1956 before completion of this latter program, and the price of tungsten concentrates declined sharply. The price had dropped to $15 per short ton unit, duty extra,6/ by the last part of July 1957.

Jan 1, 1960

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

5. Development of Initial Probing System 5. 1 Introduction The preliminary evaluation of a variety of potential methods for initial probing showed that the optical system using closed circuit television (CCTV) and the sonar, or acoustic ranging, system were the most promising. The former is capable of pro¬viding a visual display of the mine passages in a clear, non-smoky environment, and the latter is capable of providing a map of the spatial location of the coal surfaces making up the entries, as well as objects, such as cribs, mining machines, etc., in the passages in both smoky and non-smoky environments. The sonar system used in conjunction with the CCTV in a clear environment can greatly assist in resolving the spatial distribution of objects seen on the TV screen. Further, in a smoky environment the interpretation of the sonar information could be facilitated if some visual information were also available. CCTV systems exist but require some modifications to suit this particular application. The Industrial Hazards and Communications Division of the Bureau has an ongoing program for the development of such a CCTV system. Rather than duplicate this effort in developing a CCTV system, it was decided to evaluate the possibility of utilizing their system for initial probing, while continuing with the develop¬ment of a system which would work in any environment, including the presence of dense smoke. The concept of using sonar for the initial probing of mine passages represents the application of new technology requiring development. The results of such a development effort undertaken during the course of this program are described in the following sections.

Jan 1, 1973

By E. L. Sweeney

The mine and mill of the Davis-Dunkirk Lines, Inc., are about 16 miles by road south of Prescott, Ariz., which is the nearest railroad point for receiving mine and mill supplies and for shipping concentrates to smelters. A good trucking road reaches within 2 miles off the property, but from that point the grade is very steep. Outgoing loads are limited to 2 tons. The topography near the mine is exceedingly rugged, and the area is slightly wooded. The climate is mild excepting in a few winter months, when the snowfall is heavy. Electric power is secured by way of a 4 1/2-mile, high-tension line connecting with the main line of the Arizona Power Co. The concentrator was intended to treat 60 tons or more daily of gold-silver-copper ore and make a single gold-silver-copper concentrate for shipment to a copper smelter.

Jan 1, 1933

By R. W. Stahl

One of the broad purposes of the Bureau of' Mines since its establishment has been conservation of mineral resources. As some of the coal beds approach depletion, especially those coals suitable for making metallurgical coke, more and more attention is being given to means of recovering a larger percentage of coal in place. The customary system of mining in the United States is by room and pillar, or some variation thereof, which leaves pillars of coal to support, the roof. In many operations, where the pillars are not systematically recovered, the loss of coal often amounts to 50 percent or more of the original deposit. In many instances in developing new mines, It is planned to recover chain and barrier pillars on retreat when the mine has reached established boundaries. Too often, however, mines are abandoned for some unforeseen reason before completion of mining without recovering any pillars. Usually, these pillars are lost forever. With this in mind, the Mining Division, Region VIII, of the Bureau; of Mines is encouraging mining by longwall methods. It is a generally known fact that almost all of the European coal is mined by longwall methods, which are conducive to a high percentage recovery of coal. A comparison between mining systems usually is on the basis of tons per man per shift. Unless all operating conditions are similar, such a comparison could be misleading. Generally, the output per man shift in European longwall mines is less than that obtained in room-and-pillar mining in the United States. In European mining, maximum recovery of coal is not only mandatory but it must be accomplished without major damage to surface by subsidence. These restrictions necessitate packing or stowing with consequential increases In manpower and decreases in output per man shift.

Jan 1, 1954

By I. D. Shah

The copper-nickel ore of the Duluth Gabbro Complex in northeastern Minnesota is a large potential domestic resource of cobalt and platinum-group metals. However, because of the low grade of the primary metal values (0.5 pct Cu, 0.15 pct Ni), the private sector has assigned a relatively low priority to the development of technology for processing this ore, anticipating that mining probably would not begin until the mid-1990's. Furthermore, preliminary processing flowsheets considered by the mining companies centered on the primary metal values. As part of an effort to help provide the basis for technology to recover critical and strategic minerals from domestic resources the Bureau of Mines is investigating methods to recover all of the mineral values, in the Duluth Gabbro material, with particular attention to the byproduct critical minerals. A key step in this process is the removal of a relatively large amount of iron present in the bulk sulfide flotation concentrate to permit subsequent extraction of mineral values. This report describes a direct smelting method that removes most of the iron and produces a copper-nickel-cobalt matte, an intermediate product from which the metal values subsequently are separated. Copper, nickel, and cobalt grade and recovery data are presented for the direct smelting method. Test results showed that under certain conditions some of the mineral values reported to the slag, requiring slag cleaning to recover them.

Jan 1, 1983

By Oliver Bowles

Enormous quantities of limestone are used for metallurgical purposes. Approximately 23 million tons were so used in the United States in 1925 chiefly for smelting iron ores in the blast furnace. Smaller amounts are used in basic open-hearth steel manufacture, and in smelting lead, copper and antimony ores. Most limestone producers lave little knowledge of the way in which their stone is used in metallurgy. Maximum tolerances of silica, alumina, sulphur and possibly magnesium; and minimum content of calcium carbonate may be arbitrarily fixed for the guidance of the producer, but aside from these requirements little information is available to producers on the manner in which their stone is used, the office it performs in smelting, or the effects of impurities. More complete [wledge] of utilization would enable limestone operators to solve their production problems more intelligently.

Jan 1, 1927

Etching solutions containing hexavalent chromium ions (e.g., chromic acid) are used in brass finishing, printed circuit board etching, preparation of plastic for plating, anodizing, and various other industrial surface treatment operations. As the solutions are used, hexavalent chromium ions are reduced to their trivalent state, contaminants accumulate in the solution, and the effective acid concentration is reduced. When the etching rate becomes unsatisfactory for the particular operation, the solutions are discarded. This is a problem because the discarded solutions are pollutants, and because replacing the etching solution is expensive. The Bureau of Mines has developed a process for regenerating these spent solutions and returning them to the surface treatment operation without interrupting the etching process. An electrolysis cell containing anode and cathode compartments that are separated by permeable membranes, is used for regenerating the spent solutions. The spent chromic acid solution is fed to the anode compartment and sui (uric acid is circulated in the cathode compartment. Application of a steady electrical potential of a few volts dc across the electrodes causes the copper ions and other contaminants in the spent solution to migrate through the membrane to the cathode compartment where copper is plated onto the cathode. Zinc and the other contaminants remain in the sulfuric acid. At the same time, the complex, trivalent chromium ions in the spent solution are attracted to the anode where they are oxidized to their original hexavalent state. The regenerated solution in the anode compartment is then recycled back to the plant?s etching operation for reuse.

Jan 1, 1980

By D. A. Reynolds, L. P. Rockenbach

"The method of analyzing light oil for benzene is fully described by Fieldner and others 4/ and Kester and Kolmes 5/. In this procedure, benzene is determined by shaking 20 cc. of the 79º to 81º C. boiling point cut from the fractionation of the refined light oil with 3 volumes of 98—percent sulfuric acid in an A. S. T. M. separator funnel of the type used for determining water in bitumi¬nous materials. After the mixture has been shaken 5 minutes it is allowed to settle at least half an hour and the acid is drawn off; the residual oil is reported as paraffins and the decrease in volume as benzene. The method has been found satisfactory for light oils from coals carbonized at 5000, 600°, and 7000 C. but does not give accurate, reproducible results for oils from the 800° C. tests.The content of benzene of the 790 to 81° C. cut is high, 90 to 95 percent, for 800° C. light oils, whereas for lower—temperature light oils it is considerably less. Benzene is the most difficult of the aromatics to sulfonate, hence the acid concentration must be maintained above 95 percent to insure complete sulfonation. Sulfuric acid (98 percent) reacts with benzene, but its reaction with paraffins at ordinary temperatures is negligible; however, more concentrated acid will attack paraffins and give erroneous yields of benzene. The reaction between benzene and sulfuric acid forms water that will dilute the acid. The effect of this dilution may be overcome by increasing the acid-to-oil ratio or increasing the strength of the acid. The latter, however, must not be used, because the stronger acid reacts with paraffins."

Mar 1, 1942

By David E. Nicholson

This report investigates the mechanical behavior of fine soils in a lunar environment in engineering gravity-flow bins. The ultrahigh vacuum, absence of moisture, and a lunar gravity one-sixth that of earth gravity represents a unique environment, both advantageous and detrimental to these systems. On earth, moisture and gases contained in powder masses can be responsible for complex descriptions of gravity flow. Their absence appear to simplify the lunar soil behavior. However, simulation of the lunar gravity and vacuum complicates the development of experimental data for designing bins. The properties of a dry soil powder, its behavior under one-dimensional compression, and its torsional and direct shearing strength under earth atmosphere are described in part 1 of this paper. These properties provide the parameters for a finite-element analysis to optimize the design of bins, to be described by Dr. William Pariseau in part 2. Shear tests assess the failure criteria for the material. Compression tests provide modulus and (Ko) stress-ratio values from the loading portion of the compression cycle, duplicating the condition of a bin at rest with the discharge closed. During the unloading portion of the compression cycle (soil overconsolidated), the residual Ko values rise. It is postulated that this phenomenon creates a high-lateral stress in bins when they approach incipient flow. Assessment of the Ko value, overconsolidation ratio, and the void ratio state is proposed as a criterion to determine the flowability of powder.

Jan 1, 1971

By D. W. Richardson

This Bureau of Mines publication provides the enthalpy of formation of malachite [Cua(COs)(OH)2] as determined by hydrochloric acid solution calorimetry. At 298.15 K the enthalpy of formation from the component oxides is -15.l0±0.30 kcal/mole and from the elements, -251.9±0.5 kcal/mole.

Jan 1, 1974

By William L. Crentz

1. SALES PUBLICATIONS

Nov 1, 1949

By Eugene T. Sheridan

The 23d annual survey of the peat industry by the Bureau of Mines, United States Department of the Interior, revealed that 75 producers in 17 States re-ported commercial production of peat in 1956. Forty-seven producers reported humus production, 19 reported reed-sedge peat, 17 reported moss peat, and 1 reported muck. This total exceeds the number of active operations, but several producers reported recovering more than one type of peat. Fifty-five percent of the total production was reported as peat humus, 30 percent as reed-sedge peat, and 15 percent as moss peat. A negligible amount was reported as other types. More than one-fourth of the total output was raw peat with no preparation, other than having been air-dried. The remainder consisted of processed peat prepared for use by cultivation, shredding, or kiln drying.

Jan 1, 1958

By Frank J. Wiebelt

The Mohawk lead-zinc mining in San Bernardino County, Calif., was examined by D. W. Butnor, an engineer or the Bureau of Mines, at the request of Dunton, Ray, and Greenwood, leaseholders. Current operations were on a marginal economic basis, and government aid was sought in an endeavor to outline ore reserves so that production might be maintained.

Jan 1, 1949

By F. E. Armstrong

Tritiated water has been used as a tracer to follow the path of leach liquids as they flow through a copper-mine dump. Semipermeable layers, produced within the dump by compaction and "stratification" of deposized dump material, restrict the vertical movement of water. Knowledge of this restriction would aid in the optimization of the leaching process. The portion of the dump of particular interest was approximately 2,000 feet long, 800 feet wide, and 200 feet high. A total of 94 curies of tritiated water was injected into the dump at the rate of 650 gpm over a period of 39 hours. The leach liquid was sampled at natural surface outflows and through a series of wells, some drilled to the bottom of the dump and others to intermediate levels. More than 3,300 samples were analyzed, most by liquid scintillation counting, but a few hundred by gas counting. Data obtained permitted calculation of flow paths, recycle times, total fluid volume, and estimates of retention times in various portions of the dump.

Jan 1, 1971

By M. M. Hassan

This report describes the analysis tools developed at West Virginia University which can be implemented to optimally design coal mine electrical systems. The basic analytical tools for all power systems are the load-flow and short-circuit analysis. Well known programs have been developed for analysis of ac transmission and distribution systems, but they are not applicable to a system which has combined ac/dc distribution, such as a coal mine power system. Furthermore, the topology of a coal mine electrcal system changes continuously due to the movement of the locomotives on the track. In the first section of this report, algorithms for carrying out load flow and short-circuit analysis of a coal mine electrical system are described. Results from the study of a typical coal mine system are presented. In the second section a method is described to optimally size power cables for cyclic loads. The method is based on the development of a thermal-electric model for a low-voltage power cable. Results from experimental verification of the model are also presented. These techniques are useful in the safe, efficient, reliable and economical design of the coal mine electrical power systems.

Jan 1, 1979

By J. Dean Warner

In 1984, as part of a project to evaluate Alaskan occurrences of certain critical and strategic minerals, the Bureau of Mines investigated a columbium-bearing regolith on upper Idaho Gulch, near Tofty, AK. The regolith is derived from weathering of a dolomitic marble and consists mostly of iron oxide minerals with accessory apatite, zircon, xenotime, rutile, monazite, and the columbium minerals aeschynite, columbite, and ilmenorutile. Two regolith lenses contain 340,000 lb of columbium resources at an average grade of 0.07 pct. Calculated composite concentrates from two regolith samples (approximately 200 lb each) contained 53 and 57 pct of the columbium at grades of 0.97 and 0.86 pct, respectively. In each case the grade could be improved to 1.1 pct Cb with a sacrifice of 9-pct recovery. The regolith's mineralogy, trace-element geochemistry, and similarity to descriptions of other columbium-enriched regoliths suggest that the underlying marble may be a carbonatite. The lack of associated alkalic igneous rocks and the stratiform nature of the regolith, however, may be interpreted as evidence for sedimentary origin of the marble. The marble and regolith are a lode source for some of the minerals in the Idaho Gulch placer deposit.

Jan 1, 1986

By H. M. Smith

In studying the chemistry of lubricating-oil fractions from so-called ?paraffin-base? crudes, one of the first requisites is a method for the separation and removal of waxy material. A method utilizing solvents for this purpose is described in this report, together with preliminary experiments with solvents that led to its development. The solvents actually used are secondary butyl alcohol, acetone, and mixtures of these.. Isopropyl alcohol was also studied. Preliminary Experiments In previous work on "intermediate-base" crude oil, following the work of Wyant and Marsh acetone had been used for laboratory separations of oil and wax. Then acetone was tried for the separation of the waxes and oils of "paraffin-base" crude, the volume of acetone required (80 parts to 1 part of oil) was found to be too great for large-scale work. For this reason the effectiveness of other solvents was studied; the separation by acetone, however, was used as a standard.

Jan 1, 1927

By H. A. Watson

Fluorine-containing polymers are comparatively new materials that exhibit very desirable characteristics not usually found in non-fluorine containing polymers. Among these characteristics are heat and flame resistance, desirable electrical properties, and chemical inertness. Polytetrafluoroethylene and polymonochlorotrifluoroethylene are examples of such polymers commercially available. In practical applications it is reasonable to expect thermal position of these materials if they are subject to high enough temperatures. The temperatures at which thermal decomposition takes place and the nature of the gaseous products of decomposition are considered pertinent data in intelligent use of these materials. The purpose of the tests discussed herein was to determine: (1) The temperatures at which gases were produced when small specimens of the two polymers were located and (2) determine the identity of the major constituents of gaseous products.

Jan 1, 1950

By R. S. Dean

The principle of explosive crushing depends upon the fact that an expandable substance contained within the pores of a solid body will disrupt such a body upon expansion. Such expansion may be obtained by the detonation of an explosive or by the sudden release of pressure of a superheated liquid. That this principle of disruption may be applied to minerals rests on the fact that cracks, cleavage planes, and pores exist in all mineral to an extent hardly conceived possible heretofore. Crushing by this method takes advantage of force applied from within the mineral rather than from forces applied from without. The application of a force from within would appear to be more effective. A consideration of the possibilities of such a method for crushing led to some experimental work of a preliminary nature, the results of which are embodied in this paper. No systematic program was followed in the work and the results are, therefore, not final and far from complete. The success attained so far, with the mediocre apparatus available seems to warrant a preliminary report, with the expressed hope that the work may be carried on as well-outline program covering such phases as have been impossible to investigate at this time.

Jan 1, 1931