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By Edmund S. Leaver

The Precious Metals Section is concerned primarily with ore-testing problems associated with precious metals and with the analysis and concentration of a large number of the strategic-mineral samples that have been included in the research program of the Bureau of Mines. During the fiscal year 1938-39, 30 projects were completed. The requests for this service are based upon the desire f the sponsor to obtain the best or most satisfactory method for maximum recovery of the minerals. In many instances it is a question of improving present milling practice, with due regard to utilization of present equipment. In others, the probable tonnage available maybe the deciding factor in the choice of a particular recovery method. Under all circumstances the results of tests axe prepared with the thought of aiding a competent metallurgist, familiar with local conditions, to formulate a practical flow sheet or to assist the mill operator to correct known losses. A microscopic examination for identification of the mineral constituents and their association in each ore is always a big help, in planning the tests and may indicate the reason for former troubles or assist with best procedure.

Jan 1, 1940

By Edmund S. Leaver

The Precious Metals Section is concerned primarily with ore-testing problems associated with precious metals and with the analysis and concentration of a large number of the strategic-mineral samples that have been included in the research program of the Bureau of Mines. During the fiscal year 1938-39, 30 projects were completed. The requests for this service are based upon the desire of the sponsor to obtain the best or most satisfactory method for maximum recovery of the minerals. In many instances it is a question of improving present milling practice, with due regard to utilization of present equipment. In others, the probable tonnage available maybe the deciding factor in the choice of a particular recovery method. Under all circumstances the results of tests axe prepared with the thought of aiding a competent metallurgist, familiar with local conditions, to formulate a practical flow sheet or to assist the mill operator to correct known losses. A microscopic examination for identification of the mineral constituents and their association in each ore is always a big help, in planning the tests and may indicate the reason for former troubles or assist with best procedure.

Jan 1, 1940

By James C. Cawley

The Bureau of Mines conducted an investigation to statistically determine the mean current or voltage for resistive, inductive, and capaci-tive circuits that would cause spark ignitions in 8.3% methane-air, 5.3% propane-air, and 7.8% ethylene-air mixtures. Each mean ignition current or voltage was determined on the basis of 100 trials. Each trial consisted of 400 revolutions, 200 in each polarity, at 80 rpm of the standard breakf1ash apparatus. In general, spark ignition curves published in UL 913 for resistive and inductive circuits represent approximately the mean current values determined in this study, while published capacitive circuit values in methane are considerably less than the mean voltage values from this study, especially for a capacitance of less than 100 ~F. For resistive and inductive circuits, spark ignitions were obtained at currents con-siderably below those in the published curves, but this study was not optimized to find minimum ignition values. This report defines "safety factor" as applied to intrinsic safety testing as the energy ratio of the mean values of ignition current or voltage for two test gases. The safety factors presented in this report are not constant with voltage or current and, therefore, are not recommended for use.

Jan 1, 1986

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 L. L. Brown

As part of the Federal effort to help maintain an adequate supply of fertilizer materials, the Bureau of Mines conducted research to characterize complex low-grade Michigan phosphate materials and to devise methods for recovering fertilizer-grade phosphate concentrates. The rock is from middle Precambrian sedimentary formations in the Marquette Range located in the central part of the Upper Peninsula of Michigan. Occurrence of phosphate-bearing sediments in Precambrian rocks is rare. This deposit, containing 12 to 15 pct P205, is believed to be the richest Precambrian phosphate deposit in the United States. Petrographic examination showed that the conglomeritic rock contains crystalline apatite both in "black pebbles" and in quartz matrix. Attrition scrubbing and sizing tests showed that there is no tendency for phosphate to concentrate in any of the sized fractions. In beneficiation tests, which included grinding to minus 325 mesh followed by phosphate mineral flotation using a fatty acid-fuel oil collector, a phosphate concentrate was obtained that had a grade of 30 pct P205 and a P205 recovery of 72 pct. This concentrate should be suitable for fertilizer manufacture.

Jan 1, 1981

By William C. Larson

This Bureau of Mines report discusses uranium in situ leach mining in the United States to acquaint the public with an overview of this emerging mining technology. This report is not intended to be a technical discussion of the subject matter, but rather should be used as a reference source for information on in situ leaching. A list of in situ leaching publications is included as well as engineering data tables for almost all of the active pilot-scale and commercial uranium in situ leaching operators. These tables represent a first attempt at consolidating operational data in one source, on a regional basis. Additional information is given that discusses the current Bureau of Mines uranium in situ leaching research program. Also included is a listing of various State and Federal permitting agencies, and a summary of the current uranium in situ leaching operators. Finally, a glossary of terms has been added, listing some of the more common terms used in uranium in situ leach mining.

Jan 1, 1978

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 W. P. Haynes

The Bureau of Mines has been studying a modified steam-iron process using coal-derived producer gas for making either hydrogen plus carbon monoxide or methane. To provide a guide for this experimental study, compositions of equilibrium product gases for the reaction of steam plus carbon dioxide with iron were calculated and are discussed in this report. The calculations, which are described in this report, are based on thermodynamic data in the literature and cover temperatures from 800° to 1,300° K., pressures from 1 to 30 atmospheres, and hydrogen-to-carbon atomic ratios in the gas of 4 to 12. The equilibrium gas compositions are discussed in regard to making hydro-gen, carbon monoxide, and methane in the oxidation step of the modified steam-iron process. From the viewpoint of thermodynamics alone, assuming the reactions reach equilibrium, the discussion considers the effects of temperature, pressure, and composition of feed gas upon the composition of the product gas, the degree of oxidation of the iron, and the possible deposition of carbon. The results indicated the following: (1) Nearly all the carbon can be converted to methane at low temperatures (800° to 900° K.) and high pressures (over 20 atmospheres); (2) to obtain high yields of synthesis gas, high temperatures are required. For example, at 30 atmospheres, a temperature over 1,200° K. is required to convert 60 percent of the steam plus carbon dioxide to hydrogen plus carbon monoxide. Lower temperatures may be used at lower pressures) (3) oxidation of the iron increases with increasing pressure and decreases with increasing temperature; and (4) process conditions favoring carbon deposition were found within the range of variables studied, but it is thermodynamically possible to operate the oxidation process with steam and carbon dioxide outside this range of carbon deposition.

Jan 1, 1961

By FREDERICK L. WARD

This paper , describing the operation of the Ward Sand and Gravel Co.'s plant at Oxford , Mich . , is one of a series being prepared for and published by the United States Bureau of Mines on methods and costs of mining and preparing sand and gravel throughout the United States . These papers are designed to disseminate technical information regarding the methods used . The cost tabulations represent local operating expenditures only and not total production costs . It is recognized that publication of total costs might in some instances cause embarrassment to individual producers as well as to the industry as a whole . On the other hand , operating costs are essential to the technical discussion and study of the methods employed . The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue . The plant described is a dredging operation with many unique features ; especially noteworthy are the mining of the sand and gravel with hydraulic jets operating on the principle of a water ejector , the unusual construction of the dredge and the self- unloading barges that tend it , the transportation of the sand and gravel to shore in barges instead of in pipe lines , the large storage capacity of the plant , and the fact that all material goes into storage before being shipped .

Jan 1, 1932

By C. E. Wyndham

The occurrences of manganese In Alabama were reported to be widely scattered over the northeastern section of the State, and these were examined before a development project was started.2/ The most promising and available showings were chosen for further investigation, which include 1 deposit in Goshen Valley, 6 in the Rock Run area, and 2 in the northern section of Calhoun County. The work was performed by the Bureau of Mines from July 29, 1949, to February 17, 1950. The work consisted of power auger drilling 69 holes 3-1/2 inches in diameter and totaling 2,548.4 linear feet. The accuracy of samples from auger drill holes in this type of deposit was determined by sinking two shafts a total depth of 68.17 feet, from which channel samples were cut. Sixteen rotary core holes totaling 1,048.7 linear feet were drilled with a 3-inch, double-tube core barrel. Twenty-two diamond core holes were drilled with a 2-1/8-inch, double-tube core barrel and NX diamond bit. In addition to the above drilling 220.8 cubic yards of soil and rock was excavated by hand from 403.9 linear feet of trenches and 69.7 feet of test pita. A total of 206 samples were taken and analyzed for manganese, iron, cobalt, nickel, and insoluble.

Jan 1, 1953

By Raymond B. Ladoo

"The talc and soapstone deposits of Vermont have been worked more or less continuously for nearly 100 years, but all of the early efforts seem to have been directed toward the production of slabs for foot warmer, and other similar uses. Altho soapstone of good quality occurs at several places, much of the material first utilized was really talc and was not massive enough to be cut successfully. The grinding of talc in Vermont seems to have commenced in about 1902 and has shown continuous growth since that time. Statistics compiled by the Geological Survey in Mineral Resources of the ,United States show that the production of talc in Vermont has increased, from 8,978 short tons valued at $65,525 in 1905 to 93,960 short tons valued at $625,150 in 1917. Until 1917, New York was the leading producer in both tonnage and value with Vermont second, but in 1917, Vermont took the lead in tonnage produced, although not in value, with a production of over 47% of the total tonnage produced in the United States and over 35% of the world's pro-duction. This increase in production will probably be continued, though possibly at decreased rate, for the reserves of talc In Vermont are large.Active talc mines and mills in Vermont are found in four districts: Chester, Windsor County; Rochester, Windsor County; Waterbury, Washington County; and Johnson, Lamoille County, These mines and mills are distributed as shown in the following table:While there are a great many other known deposits of talc and soapstone in Vermont, some of which have been worked, those listed above are the only ones which have survived and are producing on a commercial basis. The closing down of many mines and quarries, for example, those at Perkinsville, Stockbridge, Reading, Cavendish, and Athens, has been attributed to several causes. Of these causes the most important seem to be exhaustion of the deposit, poor grade, long haul to the railroad, poor management due to lack of knowledge of mining methods and failure to consider talc mining strictly as a business proposition. The companies which are now operating with greatest apparent success are those which have realized the present and future possibilities of their industry, and have invested sufficient capital in both equipment and personnel to establish their companies on a firm business basis."

Sep 1, 1919

By H. F. Yancey

Traditionally the Pacific Northwest has relied on hydroelectric power, which has been both abundant and cheap. However, comparatively few hydroelectric sites capable of providing low-cost power remain, therefore the need for supplemental thermal generation, perhaps within the next decade, is generally recognized. Based on the present cost and availability of competing fuels, coal seems to be the logical choice for projected thermal power plants. Power companies and public utilities have become interested in establishing reserves of coal for future use. One deposit explored in 1958-59 lies in southern Thurston and northern Lewis Counties, Wash., near Centralia. Drilling, totaling 22,700 feet, proved the existence of 70 million tons of strippable coal--an ample reserve for the projected power plant. The coal, like most others and particularly those of Washington and Oregon, when mined in full seam section by mechanical methods, would require cleaning to make it suitable for use. The amount and nature of the impurities in this coal dictated a thorough investigation of its cleaning characteristics to establish economic factors and to insure proper preparation-plant design. Therefore, arrangements were made through a cooperative agreement to conduct such work at the Seattle Coal Research Laboratory of the Bureau of Mines. This report describes that investigation. The results are of interest primarily in connection with the utilization of this particular deposit, but some of the information developed is applicable to other deposits of low-rank coals in the West, because the impurities in these coals differ greatly in behavior from those generally associated with the higher rank coals of the Appalachian field.

Jan 1, 1961

By Leonard Obert

The investigation reported herein is concerned with the generation and propagation of the strain wave produced in rock by the detonation of a high-velocity explosive. This report is the second of a series that will deal with this and related problems. The rock type in which these experiments were carried out was greenstone. Subsequent reports will discuss similar investigations in other rock types. Specifically, the problem under study is concerned with how certain characteristics of the strain wave, such as the maximum compressive and tensile strain, the maximum time rate of change of strain, the frequency components present in the pulse, the duration of the pulse, and other measurable characteristics, vary with the size of the charge and the distance from the detonation point to the point of measurement. . Other investigators have studied certain aspects of the generation and propagation problem in rock. However, in these studies the travel distances from the detonation to measurement point were comparatively long and the frequency components in the explosive wave were usually under 100 c.p.s. In this study the detonation to measurement distance covered. the range from 2 to 54 feet, and the strain gages and recording equipment employed in the instrumentation of the problem had a frequency response range from 200 to 10,000 c.p.s.

Jan 1, 1950

By T. E. Gray

This report describes preparation characteristics of the significant coalbeds in Marion County, W. Va., as determined by the Bureau of Mines. It is one in a series telling what coals are suitable for producing metallurgical coke, either as mined or after beneficiation. Over 9.4 million tons of coal was produced in Marion County, W. Va., in 1958, of which almost 6 million tons was cleaned mechanically in nine cleaning plants. All of the coal mechanically cleaned came from the Pittsburgh bed. The Bureau of Mines estimated that 1,578 million tons of recoverable coal remained in the county in beds 28 inches or more thick as of January 1, 1955.

Jan 1, 1960

By G. V. Sullivan, G. F. Workentine

Beneficiation studies were conducted by the Bureau of Mines on three samples of low- grade chromite - bearing material from the Stillwater complex of Montana . The objective of the study was to develop methods for recovering chromite from low- grade materials to improve the domestic reserve situation . Samples were obtained from the three largest deposits in the district , Mouat , Benbow , and Gish . The chromic oxide ( Cr₂ 0 ) content of the ore and of the chromite was about the same in each of the samples . The major gangue constituents ranged from clean olivine in the Mouat sample to such altered minerals as serpentine and talc in the Benbow and Gish samples . Tabling , flotation , high- tension electrostatic separation , and combinations of processes were applied to each ore . Treatment of the Mouat sample ( 9.95 percent Cr₂ 0 ) by high- tension electrostatic separation , a combination of tabling and high- tension electrostatic separation , and tabling with middling retreatment resulted in concentrates that graded 42.8 , 42.0 , and 40.7 percent Cr₂03 at chromium recoveries of 85 , 86 , and 84 percent , respectively . Other techniques were less selective . 2 The Benbow sample ( 7.75 percent Cr₂0 ) responded most selectively to tabling with middling retreatment and a combination of tabling and hightension electrostatic separation to produce concentrates of 40.1 and 39.5 percent Cr₂g with each process having a chromium 2 recovery of 69 percent . Response of the Gish sample ( 8.04 percent Cr₂03 ) to the various concentration techniques was about the same as that of the Benbow sample , but in general , somewhat less selective . A combination of tabling and high- tension electrostatic separation resulted in a concentrate that contained 71 percent The Mouat mine was reopened in 1953 when the American Chrome Co. contracted with the Federal Government to produce 900,000 tons of chromite concentrate . The ore , averaging 20.2 percent Cr₂03 , was treated by tabling to produce a 38.5 - percent Cr₂ O concentrate.

Jan 1, 1964

By Robert W. Ageton

Optimal planning for mining the deep, lead-zinc-silver deposits of the Coeur d'Alene mining district, Shoshone County, Idaho, could be facilitated by a knowledge of the magnitude and direction of the pressure acting in the virgin rock. The distribution of primary stresses should be considered in order to prevent possibly destructive mining-induced stress concentrations. This particular investigation was concerned with determining stress in a zone 4,000 feet below the surface and known to be ender stress concentrations due to mining operations. Disking of the stress-relief cores obtained in a vertical down hole permitted qualitative evaluation from visual observations; the results indicate that a high lateral stress existed at the time the measurements were made. Stress-ellipsoid determinations gave a compressive principal stress of -13,000 psi oriented about N 45° W and nearly horizontal, a compressive principal stress of -11,000 psi oriented about S 45° W and abut 60° off the vertical pointing away from the vein, and a compressive principal stress -5 -7,000 psi oriented N 45° E and about 60° off the vertical, pointing toward the vein. Subsequent to the overcoring stress-relief drilling, a rock burst occurred about 100 feet northwest of the test site.

Jan 1, 1967

By G. St. J. Perrott

Through the development of manufacturing processes whereby ethylene glycol can be made on a large scale; ethylene glycol dinitrate is now being used in high explosives (dynamites and permissible explosives) by some manufacturers as a low-freezing ingredient of the "explosive oil" instead of such compounds as nitropolyglycerin and nitrosubstitution compounds. The amount of ethylene glycol dinitrate being used constitutes 25 to 50 per cent of the oil. The purpose of this report is to give the results of toots, to determine the effect on the safety and physical properties of permissible explosives of subsituating 25 peg cent of ethylene glycol dinitrate for an equal amount of nitroglycerin or a mixture of nitroglycerin and nitropolglycerin.

Jan 1, 1929

By John Nagy

Dust explosion data obtained in laboratory tests by the Bureau of Mines are presented for 181 miscellaneous materials that present an explosion hazard. Data are given also for 50 dusts that present primarily a fire hazard and for 88 dusts that did not present an explosion hazard.

Jan 1, 1968

By William E. Dennis

"INTRODUCTION The San Antonio Canyon prospect was examined by engineers 3/ of the Bureau of Mines in March 1943 and again in October 1944. In July 1944, the United States Geological Survey mapped the prospect and submitted a report 4/ recommending core drilling by the Bureau of Mines. The drilling project, which was supervised by the author, was started on January 10 and completed on May 10, 1946.ACKNOWLEDGMENTSIn its program of investigation 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 project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual investigative work, and prepares the final report. The Metallurgical Branch, O. C. Ralston, chief, analyzes samples and performs beneficiation tests. Acknowledgment is made to W. D. McMillan, engineer in charge of the Austin field office, and to J. H. Hedges, chief of the Tucson Division, Mining Branch, for general direction and advice. The samples were analysed in the laboratory of the Metallurgical Branch at Rolla, Mo., C. Travis Anderson, chief."

May 1, 1947

By Donald F. Reed

In its investigation of old, abandoned, lead-zinc mines at which records of operations are not available, in 1914 the Bureau of Mines dug surface trenches anti', in 1947 It diamond-drilled three holes at the Albright Farm deposit in Sinking Valley. Some good lead-zinc ore had been extracted from veins in dolomitic limestone during the time of the American Revolution and as late as 1870. Since that time the only activity was sporadic prospecting and developing. Thu Bureau of Mines disclosed two additional veins by surface trenching, but diamond drilling failed to find significant lead-zinc mineralization.

Jan 1, 1949