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In September 1985, the Chairman of the Transportation, Aviation and Materials Subcommittee of the House of Representatives requested that the Director of the Bureau of Mines address the issue of South Africa and critical materials dependency in testimony before the Subcommittee. Subsequent to the testimony, the Bureau has prepared a technical report focusing on the importance of South Africa and, in some cases, its neighboring countries as suppliers of six key materials. The report includes a qualitative analysis which examines the supply shortfall resulting from a potential disruption, options that are available for mitigating the impact, and their likely effectiveness, and quantitative analyses which estimate the economic impacts in the chromium and manganese markets resulting from peacetime disruption scenarios specified by the Subcommittee Chairman. The concluding section treats the role and capabilities of the Bureau of Mines in dealing with mineral supply disruptions.

Jan 1, 1986

By G. Richards Gwinn

Vermiculites are secondary minerals formed by the: alteration of biotite and philogopite mica and are associated with basic rocks such as dunites, serpentines, and pyroxenites. Vermiculite was first described by T. H. Webb in 1824. It remained a mineralogical curiosity until 1913, when the first commercial deposit was discovered in the Turrett mining district of Colorado. Expanded or exfoliated vermiculite was first marketed in 1915 from a deposit in this district 5 miles southeast of Hecla, Colo. This activity was brief, but successful and continuous commercial development began in 1921 in Montana. 'Deposits in other States have been found and developed, but Montana is by far the largest producer. Vermiculite has also been found in South Africa, Western

Jan 1, 1944

By Erle C. Donaldson

Bureau of Mines engineers examined the chemical and biological treatment of sewage water designed in one case for reuse and in another for subsurface injection. In the first case discussed, approximately 6 million gallons per day of sewage are treated by the activated sludge process followed by tertiary treatment that includes ion exchange. The renovated water is used in the industrial complex. Liquid industrial waste is sent to a waste disposal facility where it is treated for injection into a deep subsurface formation. In the second case, a community of 3,000 people is using a lagoon sewage treatment system followed by subsurface injection of t- treated effluent. Subsurface disposal is used to avoid growth of algae and weeds in a nearby lake to which the treated effluent was originally discharged. The renovation of municipal water for reuse provides a source of water for industries in a semiarid region and may also provide a source for domestic use in densely populated regions where domestic water requirements have priority over industry needs. In addition both waste treatment systems provide examples of the use of subsurface waste disposal to avoid pollution of surface streams.

Jan 1, 1971

By L. O. Bacon, H. R. Joesting, J. H. Getz

"INTRODUCTION For a number of years manganiferous iron ore has been mined on a small scale at Boston Hill, in Grant County, N. Mex. Total production up to 1943 is estimated to be over 793,000 long tons, containing 8 to 35 percent manganese and 26 to 46 percent iron. 4/ During 1941 to 1943 production was estimated to be 206,000 long tons, containing about 13 percent manganese and 37 percent iron. During 1944 daily production was several hundred tons, mostly from a single open pit. Several moderately large deposits have been mined: and many smaller ones have been found.From February to April 1945 geophysical surveys were carried out on Boston Hill by the Division of Geophysical Exploration, in cooperation with District 5, Central Region, Bureau of Mines, to determine if hitherto undiscovered manganiferous iron deposits exist. Field work was interrupted for a total of about 1 month during this period by work on other projects in nearby areas. Previous to the geophysical surveys, a preliminary examination was made by H. R. Joesting to determine if geophysical methods could be utilized in exploring the area. 5/Field measurements were made by L. O. Bacon and J. H. Getz, project geo¬physicists of the Bureau of Mines, under the general supervision of H. R. Joesting. A grid survey of the area, to locate geophysical stations, was made by Paul Russell, Bureau of Mines engineer, who also collected specimens for laboratory tests. Most of the computations and the preliminary magnetic and resistivity maps were made by L. 0. Bacon."

Feb 1, 1948

By B. L. Razzaboni, P. Bolsaitis

"The formation of reactive oxygen species resulting from the interaction of silica dust particles with red blood cell membranes was investigated; particularly, the effect of surface hydroxyl (silanol) group concentration on the rate of formation of such reactive oxygen species was investigated. The rate of formation was measured indirectly through the effect of catalase, a hemoprotein peroxidase, on silica-induced hemolysis. It was found that the addition of exogenous catalase to erythrocytes markedly reduces the hemolysis caused by silica particles. Furthermore, the amount of catalase required for deactivation of silica per unit area of particle surface is lower for fumed silica particles and calcined crystalline particles than for uncalcined, crystalline silica, suggesting a correlation between the concentration of OH groups at the silica particle surface and its potential for generation of H2O 2• The addition of albumin, a copper chelator, also decreases hemolysis. These results suggest that the hemolysis caused by silica particles is at least partly related to the formation of H2O2 at the particle surface and its subsequent reaction with Cu+ ions. The relationship between the concentration of surface silanol groups on the silica surface and the amount of catalase required to decrease hemolysis may also provide a method for testing potential fibrogenicity of respirable dusts. IntroductionReactive hydroxyl groups on silica surfaces are known to be cytotoxic and are believed to play a major role in silicosis (1-9). It has been proposed that this cytotoxicity results from hydrogen bonding to cell membranes and a resulting increase in membrane fluidity and permeability (4). Surface hydroxyl groups on silica surfaces have also been shown to interact with carbonyl oxygens in cell membranes (1,5). An extensive study by Nolan et al. (6) of the relationship between the negative surface charge resulting from ionized silanol groups and the hemolytic activity of crystalline a-quartz (Min-U-Sil) has shown a positive correlation between hemolytic activity and the surface concentration of silanol groups. These authors demonstrated that the hydrogen bonding of polyvinyl-N-oxide (PVPNO) with silanol groups, as well as the bonding of metal cations to the ionized sm- groups, results in significant decreases in hemolytic activity. Furthermore, it has been found that the complete removal of surface hydroxyl groups from the surface of respirable silica particles nearly eliminates the hemolytic potential of silica (7), suggesting that hydroxyl groups might be involved in other cytotoxic processes associated with silica-induced lung injury. Reactive oxygen species have been .implicated in cellular damage caused by respirable silica particles. Evidence for the presence .of oxygen radical species (02, OH°, H2O2) generated by silica, especially on freshly formed surfaces, has been produced by various investigators. Kalbanev et al. (8) detected H2O 2 in aqueous suspensions of quartz. Electron spin resonance and spin trapping by Shi et al. (9) confirmed the presence of OH"" radicals in aqueous suspensions of quartz, and Gulumian and van Wyk (10) suggested that both glass and quartz produce hydroxyl radicals in the presence of H2O 2 • Gabor et al. (11) detected the presence of malondialdehydereactive lipid peroxides (i.e., lipid-0°) in cultures of macrophages and respirable silica particles using the thiobarbituric acid (TBA) reaction test. Will (12), however, reported that iron enhances the TBA value of peroxidized lipids, and Scheulen and Kappus (19) found that catalase augmented malondialdehyde formation, thereby increasing the TBA values."

Jan 1, 1990

By J. O. Winget

Phosphonic acid and iminodiacetic acid chelating resins were investigated to assess their potential as selective ion exchangers for separating lanthanide elements and yttrium . The affinity of phosphonic acid resin for lanthanides increases with increasing atomic number , and that of iminodiacetic acid resin for lanthanides increases with atomic number to a maximum for element 62 and then declines with atomic number throughout the remainder of the series . Elution sequences of the elements with mineral acid eluants corresponded favorably with equilibrium data , whereas the elution sequence obtained with chelating eluants was proportional to the relative values of the stability constants of the chelating agents with the lanthanides . Separation of lanthanide mixtures into groups of light and heavy elements with iminodiacetic acid resin appears feasible .

Jan 1, 1964

By Carl Belser

This paper, covering Chaffee, Fremont, Gunnison, Lake, Larimer, Park, and Summit Counties, Colo., is the second of a series reporting on the tungsten potential of the Colorado region. The assembled information was obtained by examination of some properties, personal contacts with owners, and access to unpublished reports by other engineers. The tungsten-bearing areas of the 7 counties cover approximately 400 square miles and are in 10 distinct areas, which vary in size (fig. 1) from 1 square mile up to 290 square miles. The tungsten mineral wolframite was discovered by a man named Hackay near Dale on the Florence & Cripple Creek Railroad in the early 1900's, and wolframite and hubnerite were noted at Climax and the adjacent areas in Lake and Summit Counties at an early date, but no records of shipment from any of the areas are available before World War II. It is not known when scheelite was first discovered, but it was recognized in the Stockton mine during World War I. In the counties listed 64 properties are known to contain tungsten; of these, 18 have had some commercial output, although only 3 of them produced in 1953. The total production through 1953 is estimated at 115,000 short-ton units of tungsten trioxide. In 1953 by far the major portion came from the Climax mine.

Jan 1, 1956

By Steve W. Webb

The Bureau of Mines is researching a new technology for dewatering clay suspensions that consists of flocculation by high-molecular-weight poly-ethylene oxide (PEO) polymer and subsequent removal of water from the floes via a trommel. The minimum amount of PEO required to dewater the clays depends on the ions adsorbed on the surface of the elay particles. Infrared studies were performed on clays with Li+, NH4+, K+, Mg2+, Ca2+, Ba2+, or 8r2+ adsorbed, with and without adsorbed PEO, to develop data to aid in understanding the dewatering mechanism. Hydroxyl stretching modes between 3,400 and 3,250 em-I, associated with water adsorbed on the clay, showed changes in intensity proportional to the ionic eharge-to-radius ratio; that is, the ionic potential. In addition. a water-bending vibration of adsorbed water at 1,630 cm-1 showed variations associated with water desorption. The data are consistent with changes in adsorption of PEO resulting from variation of the acidity of water coordinated with the exchange ions, induced by the variation in field strength of the ions with the ionic potential.

Jan 1, 1986

By John W. Cole

The Bureau of Mines conducted a trenching and sampling project during 1947 on the tungsten-rich granodiorite that outcrops in Henderson Gulch, Montana. During the course of this investigation, interest was attracted to the Sunrise copper-gold mine in metamorphosed limestone in the north slope of the gulch. The mine was examined by S. H. Lorain, Chief, Mining Division, Albany Branch, in May 1948. A trenching and drilling program was recommended to develop a parallel vein indicated by outcrops to lie below the principal productive Queen vein. In the meantime, the Queen Mining Syndicate initiated a trenching program that exposed high-grade lead-copper-silver-gold ore in a nearly vertical vein that strikes N. 600 E. to east. A core-drilling program to develop this vein was initiated in September 1948. This report presents the factual data obtained from the trenching and drilling operations. The Sunrise mine was discovered about 1890. Production has been estimated to be $120,000 in gold from 40,000 tons of ore mined during the period 1892-1903. The tailing from this operation was treated by cyanidation in 1912, with a reported recovery of $3.50 to $4.00 a ton from 15,000 tons of material. Subsequent production of sulfide ore was 7,396 tons treated by smelting, with recovery of 1,569.42 ounces of gold, 10,003 ounces of silver, 352,899 pounds of copper, and 354 pounds of lead.

Jan 1, 1950

By E. L. Fosse, W. S. Wright

"INTRODUCTION Preliminary and detailed exploratory examinations of iron and copper ores on Prince of Wales Island have been conducted by the Bureau of Mines from early in 1942 until the end of 1944. Among these investigations was that of the Jumbo magnetite deposit, which was visited by Stephen P. Holt, an engineer of the Bureau of Mines, during a preliminary examination of the Copper Mountain and Jumbo properties September 15 to 18, 1943, During the months of June, July, and August 1944, a more detailed examination, which consisted essentially of mapping and sampling, was made by the authors working in conjunction with George C. Kennedy of the Geological Survey, Geological, topographical, and dip-needle contour maps were made of the area, and 97 channel samples were cut.ACKNOWLEDGMENTIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes sam¬ples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.Special acknowledgment is made to R. D. Stewart, Territorial Commissioner of Mines and former general manager, and to Duncan Campbell, Ketchikan, Alaska, former mine superintendent of the Jumbo mine. Acknowledgment is also due to George C. Kennedy of the Federal Geological Survey for extending cooperative assistance in topographical mapping, dip-needle surveying, and geological study of the deposits. Further acknowledgment is made to C. Travis Anderson, chief, Rolla Division, Metallurgical Branch, and other members of that division for conducting beneficiation tests on Jumbo Basin ores."

Oct 1, 1946

By R. H. Reist, R. D. Dey, V. Castranova, J. P. Durham, Y. Rojanasakul

"Silicosis is a fibrotic pulmonary disease produced by inhalation of silica-containing dusts (Peters, 1986). Chronic silicosis may develop 20-40 years after initial exposure to crystalline silica, and the disease may progress from a simple to a complicated form. Few symptoms are evident in simple silicosis with pulmonary function being relatively normal. However, chest radiographs reveal small rounded ·opacities in the upper lobes of the lungs. These silicotic nodules consist of collagen arranged in a distinctive circular pattern. As fibrotic changes become more severe, the disease progresses to complicated silicosis (progressive massive fibrosis). Complicated silicosis is associated with shortness of breath and decreases in pulmonary function characteristic ofrestrictive lung disease. Chest x rays reveal numerous large silicotic nodules which may be associated with scar emphysema. Several mechanisms have been proposed to explain the cellular events which result in silica-induced lung damage and fibrosis (Lapp and Castranova, 1993). They include: ( l) direct cytotoxicity of silica, (2) activation of oxidant and enzyme release from alveolar macrophages, (3) recruitment and activation of polymorphonuclear leukocytes, and (4) stimulation of fibroblast proliferation and collagen synthesis.Tetrandrine is a bisbenzylisoquinoline alkaloid derived from the Chinese herb Radix Stephania tetrandra. It has a molecular weight of 622.73 and an empirical formula of C38H420 6N2. The chemical structure of tetrandrine has been published previously by our laboratory (Castranova et al., 1991 a). Its structure is characterized by methoxy groups at C7 and C12 , uncharged nitrogens at N2 and N’2 and two 17-carbon ring members connected by a double oxygen bridge between Ca-C7 and C11-C12. Tetrandrine has been shown to reduce both silica-induced fibrosis and the elevation of lung collagen content in rats (Huang et al .. 1981; Yu et al., 1983; ldel, 1987). Furthermore, tetrandrine has been used as an antifibrotic agent in Chinese clinical trials (Li et al.. 1981 ). Preliminary results suggest that administration of tetrandrine to patients with silicosis results in substantial improvement of symptoms, increases in diffusion capacity, and decreases in the size of shadows on lung x rays."

Nov 1, 1995

By Ben E. Lindsly

The study of "bottom-hole' samples follow,-is in natural sequence the study of samples3 obtained under high pressures at the well heads of flowing wells. The principal object of this phase of gas-solubility research, started actively in January, 1530, was to gain a more accurate knowledge of the physical and chemical characteristics of the oil-gas mixtures that exist in natural reservoirs. In possession of actual data regarding the condition of the oil; the quantity of gas liberated from solution upon dimunition of pressure; and the relative volumetric proportions of gas to oil at various pressures throughout the flow string in a well, it should be possible to predict, with a fair degree of accuracy, what physical changes these mixtures would undergo throughout the life of a pool. Such information not only is important in designing flow strings in flowing wells but is important also in solving problems relating to pumping efficiency and the power required for pumping. Although certain fundamental rata Mere obtained in the stud of samples taken at the well head, "bottom-hole" samples are more representative of subsurface mixtures of oil and gas because they are obtained at reservoir temperatures, and before the oil has had the opportunity of intermingling with extraneous gas; that is, gas which either was not in solution originally, or which was liberated from solution at some higher pressure, and later became mired with the original undissolved gas.

Jan 1, 1933

By Clayton M. Rumsey

The U.S. Bureau of Mines investigated prospects and mineralized areas in and adjacent to the Indian Pass and Picacho Peak study areas in 1983 and 1984. The Indian Pass study area contains 33,640 acres and the Picacho Peak study area contains 5,450 acres. The study areas are located in the southeast corner of California and are underlain by Precambrian gneiss, Pre-Tertiary metavolcanic and metasedimentary rocks, and Tertiary volcanic and non-marine clastic rocks. Low-grade gold-silver resources may be present in hydrothermally altered gneiss in the upper plate and altered schist in the lower plate of the Chocolate Mountain thrust fault. The thrust fault is exposed in the study areas for about 3.5 miles west and 5 miles east of Indian Pass. Mineralized zones in the thrust plates were not discovered until 1983. Earlier prospecting explored areas containing minor copper carbonate occurrences in schist and sedimentary and volcanic rocks that are younger than the thrust. Twenty-three mines, prospects, and mineral occurrences inside the study areas and fourteen outs; de were examined for this study. These surficial copper occurrences have been prospected extensively in the study areas; large areas have been scraped, pitted, and trenched by bulldozers. However, they appear to be of limited economic significance. Slightly mineralized zones are in the northwest part of the Indian Pass study area where granite contacts sedimentary and volcanic rocks.

Jan 1, 1986

By W. W. Adams

"During the calendar year 1925 the Bureau of Mines received from the operators of several hundred mines and quarries complete accident records covering deaths, permanent disabilities, and “lost time” temporary injuries. Some of the companies, - those that participated in the National Safety Competition-also furnished information showing the number of man-hours of work performed during the year. With these two types of information it was possible to calculate the accident-frequency and accident-severity rates of the different plants. Complete and comparable reports of accidents and Man-hours of “exposure” were received from 34 underground metal mines, 59 underground coal mines, 15 underground mines producing other nonmetallic minerals, and 102 open quarries or open-pit mines. The figures in the table appended to this report show the accident severity rates and other data for each of the 34 underground metal mines and for the group as a whole. It is proposed to publish similar figures for the other classes of mines and quarries at an early date.The 34 metal mines listed in the table are situated in Arizona, Idaho, Kansas, Michigan, Minnesota, Missouri, New Jersey, New Mexico, Oklahoma, South Dakota., and Utah; they employed 5, 925 men, an average of 174 men per mine, including employees above-ground as well as underground. With but few exceptions, 50 men was the minimum number of employees in any mine. The total period of employment or “exposure” at the 34 mines was 14,612,607 man-hours, an average of 2,466 hours per man, or the equivalent of 308 work-days of eight hours for each employee. Accidents resulted in 15 fatalities, 9 permanent disabilities, and 1,950 temporary “lost time” injuries (causing disability exceeding remainder of shift). The fatal and nonfatal injuries represented 132,575 days of disability. Thus the accident frequency rate for the group was 135 accidents per million hours and the accident severity rate was 9.073 days lost per thousand hours of 1 “exposure”. The severity rates ranged from 0.227 to 88.653, while the ·range of the accident-frequency rates was from 16. 6 to 307 .4. In compiling the accident severity rates shown in the table, all accidents caused by explosives were weighted at twice the number of days actually lost, as one of the purposes of the National Safety Competition was to stress the prevention of accidents caused by explosives."

Sep 1, 1926

By Florence L. Feicht, H. H. Schrenk, Carlton E. Brown

This report describes the dropping - mercury electrode , its use in analysis , and the procedure of the Health Division of the Bureau of Mines in determining lead , cadmium , and zinc . The dropping - mercury electrode or polarograph is an electrolytic device , one electrode of which consists of mercury issuing in small drops from a capillary tube . Such electrodes have been in existence for more than 50 years, but they were not used for analytical purposes until about 1922.6/ Developments since have been rapid , especially in Czechoslovakia , Germany , Italy, and Japan and more recently in the United States . A recent bibliography / contains references to, 825 articles issued from 1903 through 1940. In 1939 Kolthoff and Lingane presented the first comprehensive critical review, in English , of the device and its use in analysis . They have recently issued a book on the same subject. Similar information also is included in a recent book10/ by Kolthoff and Laitinen . Much of the information in this and the two following sections on this device and its use in analysis was obtained from these three publications . The use of the dropping - mercury electrode in analysis is based upon the fact that the kind and amount of electro - reducible and electro - oxidizable constituents in solution can be determined from the current -voltage relationships revealed by this electrode or electrolytic device .

May 1, 1942

By M. J. Brevoort

Research work in the Bureau of Mines cryogenic laboratory requires the use of high-sensitivity galvanometers of the d'Arsonval type in a building that is subject to unusually severe vibrations. A modified form of the galvanometer suspension described by Julius3 has damped the vibrations so successfully that a short note concerning it is thought to be desirable, The laboratory is on the site of the Amarillo helium plant near a building that houses gas engines of from 180 to 250 hp., driving compressors and electric generators. The distances from the galvanometers to the individual engines range from about 80 to 180 feet. The subsoil, consisting of black clay loam, transmits the impulses without much damping. The usual methods of protecting galvanometers from vibration were tried and proved fruitless. A Julius suspension purchased on the market was carefully installed in the hope that it would overcome the difficulty, but the conditions were too severe even for this elaborate arrangement. Several mudifications of the original Julius suspension, which were then introduced, resulted in almost complete elimination of all vibrational effects.

Jan 1, 1931

By Wing G. Agnew

The first six Reports of Investigations in this series , pertaining to the investigation of stemming at the Mount Weather Testing Adit, dealt with ( 1 ) the dust produced by blasting , ( 2) the effect of stemming upon gases generated by blasting , ( 3 ) the relative advantages and disadvantages of different types of stemming and no stemming when used with 60 - percent ammonia gelatin dynamite , (4) the length of stemming material through which a primer will fire and detonate a charge of dynamite , ( 5) comparison of dust and gases produced when blasting charges of dynamite in drill holes , bombs, and mud - cap shots , and ( 6 ) the relative advantages and disadvantages of different types of stemming and no stemming when used with 40 - percent ammonia gelatin dynamite .

Oct 1, 1943

By E. M. SEELEY, F. S. LOTT

The total capacity of the natural-gasoline industry to produce light hydrocarbon products increased to 21,322,000 gallons ( 507,670 barrels ) daily on January 1 , 1948 , from 17,928,000 gallons ( 426,860 barrels ) daily on January 1 , 1946. Expansion of the industry in the first two post -war years , 1946 end 1947 , thus averaged 9 percent annually , compared with 6 percent annually in the last two war years , 1944 and 1945 . The number of cycle plants increased only from 37 to 39 in the years 1946 and 1947 , and total capacity of these plants gained 21 percent to 5,857,000 gallons de ily on January 1 , 1948 , represent ing 27.5 percent of the total capacity of the industry , compared with 27.0 percent on January 1 , 1946. All other plants decreased in number in the two-year period from 589 to 510 on January 1 , 1948 , but their total daily capacity increased 18 percent to 15,465,000 gallons . The daily capacity of the average plant in the industry was enlarged from 28,600 gallons on January 1 , 1946 , to 38,800 gallons on January 1 , 1948 , continuing the long -established trend to producing units of greater size and efficiency . The average cycle plant capacity increased from 131,000 gallons daily to 150,200 gallons daily on the same dates as the average capacity of all other natural -gasoline plants increased from 22,200 gallons to 30,300 gallons . Owing to the elimination of small , obsolescent plants in Illinois , Oklahoma , and Pennsylvania , these States experienced the greatest reductions in numbers of plants in 1946 and 1947. In Oklahoma and Texas , several consolidations of two or more plants into a single operating unit were reported . Louisiana and Mississippi were the only States in which the number of plants increased , but daily capacity to produce light products was larger in eleven States on January 1 , 1948, than two years earlier . Added facilities in California and Texas accounted for 41 and 36 percent , respectively, of the national gain in capacity .

Sep 1, 1948

By Ben E. Lindsly

The study of "bottom-hole samples follows in natural sequence the study of samples obtained under high pressures at the well heads of flowing wells. The principal object of this phase of gas-solubility research, started actively in January, 1930, was to gain a more accurate knowledge of the physical and chemical characteristics of the oil-gas mixtures that exist in natural reservoirs.. In possession of actual data regarding the condition of the oil; the quantity of gas liberated from solution upon dimunition of pressure; and the relative volumetric proportions of gas to oil at various pressures throughout the flow string in a well, it should be possible to predict, with a fair degree of accuracy, That physical changes these mixtures would undergo throughout the life of a pool. Such information not only is important in designing flow strings in flowing Tells but is important also in solving problems relating to pumping efficiency and the power required for pumping. Although certain fundamental data were obtained in the study of samples taken at the well head, "bottom-hole" samples are more representative of subsurface mixtures of oil and gas because they are obtained at reservoir temperatures, and before the oil has had the opportunity of intermingling with extraneous gas; that is, gas which either was not in solution originally, or which was liberated from solution at higher pressure, and later became mixed with the original undissolved gas.

Jan 1, 1933

By J. P. Bennett

The Bureau of Mines investigated the dimensional changes of ceramic materials exposed to acid environments to evaluate construction materials for emerging technology in chemical and metallurgical processes. Six commercial ceramic materials (two red shale, two fireclay, one silica, and one silicon carbide (SiC» were exposed to H20, 20 and 30 wt pct HCl, 40 and 60 wt pct HN03, and 10 and 50 wt pct H2S04 at temperatures from 50° to 90° C for 300 days. Linear expansions ranged from a low of -0.02 pct for the silica to a high of 0.45 pct for the red shale. A general ranking of the volume expansion of the materials tested, (from high to low), is as follows: high-porosity red shale A and fireclay B » low-porosity red shale B and fireclay A > silicon carbide and silica. A general ranking (largest to smallest) of the effect of exposure environments is HCl > H2S04, HN03 > H20. An autoclave test method was evaluated. Data obtained from 8-to 24-h exposures were compared with data obtained from the 300-day exposures. The relative expansion trends were similar, indicating that this method could be used as an accelerated test.

Jan 1, 1988