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By H. H. Dewing

The Bureau of Mines conducted a laboratory-scale investigation of a technique that produces zinc sulfate and elemental sulfur from sphalerite concentrates by reaction with sulfuric acid at 175° to 200° C and ambient pressure. The objective of the investigation was to develop a hydrometallurgical method of producing zinc from sulfide concentrates that does not generate sulfur dioxide pollutants. Reaction with 80-to 85-pct sulfuric acid produced 4 moles of sulfur for every 3 moles of sphalerite reacted, with minimal production of sulfur gases under optimum conditions. More than 98 pct of the zinc was recovered as zinc sulfate after 3 hours at 175° C. The reaction mixture was leached with simulated spent zinc electrolyte containing 13-pct sulfuric acid to recover zinc sulfate from the insoluble, high-sulfur residue. Neutral zinc sulfate, which is required for electrolysis, was separated from the sulfuric acid solution by crystallization as ZnS04?7H20 at -10° C. Up to 80 pct of the water in the recycled electrolysis solution was removed by the crystallization process; evaporation was used to further concentrate the sulfuric acid for reuse in leaching sphalerite. Advantages of the proposed method over conven-tional roasting and leaching include virtual elimination of sulfur dioxide, production of a solid sulfur byproduct, and higher zinc recoveries due to elimination of zinc ferrite losses.

Jan 1, 1978

By R. A. Guereca

The Bureau of Mines conducted an analysis to determine criteria for steady-state, laminar flow boundary conditions for a coiled-tube gas viscosimeter by comparing experimental data from a thick-walled, stainless steel capillary in a horizontal, straight-tube condition, with similar data taken after the same capillary was formed into a helix. Overlapping volumetric f10wrates and pressure drops are covered for both configurations at pressure levels of 28, 225, and 1,000 psia at 3000 K. Friction factor, Reynolds number, and Dean number correlation plots show conditions where the coi1ed-tube flow deviates from straight-tube flow. The coiled-tube data indicate departure from Poiseui11e steady-state laminar flow at a Reynolds number close to 390 and a Dean number of about 15. Below these conditions and consistent with the data reported, Dean's circulation appears negligible. For the particular coil used, a conservative upper limit of 10 is chosen for the Dean number corresponding to an upper limit of about 250 for the Reynolds number.

Jan 1, 1967

By D. J. MacDonald

The Bureau of Mines investigated two alternative methods for treating a zirconium-bearing chloride-sulfate strip liquor to obtain reactor-grade Zr02. One method involves neutralization with NH3 and the other hydrothermal precipitation. The strip liquor was derived from zircon sand by a Bureau of Mines method for separating zirconium and hafnium via solvent extraction with a tertiary amine. Neutralization with NH3 to precipitate hydrous zirconium oxide required 0.9 to 1.1 g NH3 per gram of zirconium. The NH3 can be recovered for recycle. Zr02 that met reactor-grade specifications was produced by precipitation with NH3? Hydrothermal precipitation of Zr02 from strip liquor required that the solution be maintained at 2600 C and 680 psi for 10 min and in a non-corrodible pressure vessel. In bench-scale experiments both methods gave-zirconium recoveries greater than 99 pct.

Jan 1, 1984

By E. L. Garton

An active list of permissible explosives was published in July, 1931, as part of United States Bureau of Mines Report of Investigations 3134, under the title of "Active List of Permissible Explosives and Blasting Devices Approved Prior to June 30, 1931." Changes in that list were authorized in August, September, October, November, and December, 1931, and January and March, 1932, as published in Reports of Investigations 3140, 3147, 3150, 3155, 3158, 3161, and 3163, respectively. By these changes the following explosives were added to the active Permissible list: Austin Red Diamond No. 1, L. F. Gel-Coalite W, L. F;" Austin Red Diamond No: 5. Gen-Gel No. 2. Black Diamond Nu-Gel No. 1 Genite C-1 Burton 1, L. F. Liberty No 4 Burton 2, L. F. Liberty No. 5 Burton 10, L. F. Peerless D Burton 12, L. F. Permigel 1, L. F. Burton F, L. F.

Jan 1, 1932

By J. M. Mutmansky

"The objective of this study was to produce coal dusts for laboratory research that are similar to mine airborne dusts in chemical, mineral, and physical characteristics. In this investigation, dusts produced in laboratory comminution equipment were compared with continuous miner- generated dust for similarity in physical characteristics. Mining-generated dust (MGD) and bulk coal samples were first collected from an underground mining operation. The bulk samples were then processed in the laboratory for size reduction in various comminution devices. These laboratory- generated dust (LGD) samples were subjected to size and microscopic analyses. Physical properties of the dust particles were studied on a scanning electron microscope (SEM ). A numerical shape coordinate system (SCS) was also developed and applied to 300 particles from each sample. Statistical analysis was then performed on the collected data and characteristics of the MGD and LGD samples were compared. IntroductionIn many biomedical studies, researchers routinely introduce a dust mass into an experimental environment to assess the response of a biological entity, usually lung macrophages in vitro or a live laboratory animal, to the dust mass. To provide data of maximum usefulness, it is highly desirable to use dust with characteristics of actual mine airborne dust. The primary objective of this research was to produce dusts in the laboratory similar in chemical, mineralogical, and physical characteristics to mine airborne dusts. This paper outlines the evaluation of the physical characteristics of the lab-generated dusts.Particle shape analysis is perhaps the least-developed area in mineral-related particle science and technology. There are still no standard methods or instruments to scientifically quantify particle shapes. To date, many attempts have been made to characterize particle shapes. These procedures can be roughly classified into three categories:"

Dec 1, 1995

By A. F. Colombo

Laboratory-scale tests were conducted by the Bureau of Mines on an argillaceous Michigan copper ore and mill tailing to determine the feasibility of leaching with acidified ferric sulfate solutions. The ore and tailings, containing 1.24 and 0.24 percent copper, respectively, were from the White Pine Copper Co., Ontonagon County, Mich. The investigation showed that ferric sulfate leaching of the ore and tailings followed a predictable pattern. Thus, with 4 hours of leaching, up to 58 percent of the copper in the ore was extracted, but prolonged leaching (2 to 3 weeks) was required to dissolve more than 90 percent of the copper. Similarly, about 50 percent of the copper in the mill tailings sample was dissolved in a few hours, but 8 days or more were required for extractions of over 90 percent.

Jan 1, 1962

By C. E. Wethered

This paper describing the mining methods employed by the Federal Mining and Smelting Co., operating the Morning mine at Mullan, Idaho, is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The daily tonnage produced at the Morning mine, including that mined by leasers, is 1,100 tons. Mine run of ore will average 9.1 per cent lead, 5.8 per cent zinc, and 4.4 ounces silver per ton. A stull set and fill method of mining is employed.

Jan 1, 1930

By Joanne L. Johnston

Researchers at the U.S. Bureau of Mines have developed a new technique for bonding strain gauges to rock bolts. These instrumented bolts are used to determine load at intervals along the length of the bolt so that reliable, consistent measurements for the design of support systems can be obtained. In this Information Circular, this technique is described in detail and should result in improved miner safety in underground mines.

Jan 1, 1993

By D. G. Kuehn

Positive ion sampling studies have been conducted on do discharges containing 0.33 percent sulfur dioxide in helium. Measurements were made for normalized gas pressures from 0.45 to 6.8 torr and discharge currents from 5 to 40 ma. Ion species observed included SO+, S+, SO2+, SO3+; O+, and 0+, 02+. Studies were conducted on the functional dependence of the various ion species with respect to axial distance, pressure, current, and gas flow rate. Interpretation of these results is consistent with the assumption of SO2 dissociation. Deposition of sulfur compounds was observed in the plasma container during these studies. The present results are compared with previous studies which have been conducted in SO2.

Jan 1, 1971

By Wilbur I. Duvall

Surface vibrations of ground, rock, and structures resulting from blasting or other sources are often measured with portable seismographs. These instruments are usually supported by a three-point mount or tripod which is simply placed on a horizontal surface on which vibration levels are to be measured. The rigid-body motion of a tripod-supported seismograph is considered from the point of view that there should be no slippage of the feet with respect to the surface and none of the feet should leave the surface as a result of imparted motion. From these studies the following design criteria are deduced which assure that the seismograph will respond accurately to vibration levels as large as 1/2 g.:3/ First, the coefficient of friction between the feet and the surface on which the instrument rests should be as large as possible, preferably approaching unity; second, the center of gravity of the instrument should be vertically above the centroid of the three-point mount; and third, the vertical distance between the center of gravity of the instrument and the centroid of the three points of contact with the surface should be less than the perpendicular distance between the centroid point and anyone of the three sides of the triangle formed by the three points of contact. Portable seismographs that do not satisfy these conditions should be clamped to the surface if vibration levels above 0.1 g. are to be recorded.

Jan 1, 1961

By R. V. Mrazek

The heat of formation of vanadium trichloride was determined at 298.15° K. Measurements were made in a solution calorimeter in which an aqueous hydrochloric acid-potassium dichromate solvent was employed. Data are presented for the heats of solution of vanadium trichloride and the vanadium trioxide "backup" compound, and for appropriate dilution reactions needed to preserve stoichiometry. The resulting heat of formation of vanadium trichioride (VCI3) at 298.15° K was found to be ?H°298.15° K = -138.89 ±0.37 kcal/g mole.

Jan 1, 1968

By A. Wahab Khair, Richard D. Begley

"This paper presents results of destructive tests performed on rectangular coal specimen under the influence of two vertical and simultaneous wedge indentation forces. Several wedge designs and spacings were utilized in compression tests. The objective of these experiments was to qualitatively monitor the effect of different wedge designs and spacings on the stress distribution within the coal specimen.Coal samples from the Waynesburg coal seam were cut and trimmed to cubical dimensions of approximately 5 X 10 X 20 cm. These specimen were subjected to parallel compressive forces through two vertically applied wedge indentors. Loading was achieved with a hydraulic hand pump in order to facilitate interferogram construction. The load increments were limited due to the sensitivity of the holographic interferometric technique (holometry) in measuring small displacements; therefore, interferograms were taken only during similar increments in order to allow for a qualitative comparison between different wedge design and spacings. In some cases, interferograms were taken immediately before and after failure of the specimen.Introduction Failure Modes Three distinct modes of failure occur when geologic materials are subjected to wedge indentation forces. As shown in Figure 1, a crushed zone is located immediately adjacent to the indentor while chipping can occur if the fractures initiated in the crushed zone extend upwards to the free surface.. The third failure mode is a zone of intricate frac¬tures located between the crushed zone and the chipping zone. Several experiments have been conducted over the years to better understand crater formation and stress distribution within geologic materials under the influence of an indentor. Generally speaking, crack initiation and propogation observed in these experi¬ments correlate fairly well with wedge indentation theory; however, the nature of the .fractures is greatly influenced by different material properties such as grain size and cleavage planes. In other words, a wide range of behavior has been found in different rocks subjected to wedge penetration. For example, it has been observed that some rocks are merely crushed and indented while others are more prone to cracking and chip formation. Therefore, the development or nondevelopment of chips depends mostly on wedge geometry, rock type and depth of penetration. This work is part of the study associated with opti¬mization of cutting parameters, which is best modeled by using brittle materials and subjecting them to rigid wedge penetration tests."

Jun 1, 1988

By G. B. Goodman, W. H. Pailes, P. D. Kaplan, I. Stachura, V. Castronova

"The risk of developing silicosis in underground coal miners, tunnel workers and some foundry workers is well-known. These persons generally develop the classic form of the disease over a prolonged period of time. Workers involved in abrasive blasting of bridges and those polishing tombstones have been reported to develop an acute form of silicosis within a few years of commencing exposure. Not well-appreciated is the potential for development of acute silicosis among drillers at surface coal mines. We report the case of a 33-year--old man who worked primarily at surf ace drilling, developed acute silicosis within three years of beginning exposure, and who initially responded dramatically to corticosteroid therapy. CASE REPORTThe patient is a 33-year-old white man who worked as a rock driller at a quarry and also at surface coal mines in western Pennsylvania since 1975. Prior to 1983, much of his work was done with a wet process in which water was applied to reduce dust generation. After 1983 he worked primarily as a driller at a surface coal mine using a dry process. He never wore a respirator. He described the dust as being so dense that he ""couldn't see anything.- In August 1986, he presented to his local physician with a complaint of pleuritic chest pain and shortness of breath. A chest x-ray film was obtained showing only a few p and q opacities. He continued working and these symptoms subsided, but the patient noted the onset of progressive weight loss. By May 1987, he had lost approximately 50 lb. In addition, he suffered profound malaise, dyspnea, migratory chest pain and arthralgia, fevers and drenching night sweats.A course of erythromycin therapy given in the hospital resulted in only fleeting improvement. Studies for Legionella and Mycoplasma infections were negative, as was a tuberculin skin test. The patient was transferred to Allegheny General Hospital in Pittsburgh on June 4, 1987.There was no history of serious medical illness, including tuber¬culosis. The patient admitted to smoking between I and 1 1/2 packages of cigarettes daily for 2 1/2 years prior to May 1987 when he stopped smoking. He denied intravenous drug abuse, homosexual activity or receiving transfusions of blood or blood products.On physical examination the patient was a thin, febrile white man who appeared chronically ill. Bilateral axillary and cervical lymphadenopathy was present. Chest examination showed restricted expansion and bilateral crackles. Examination of the heart and abdomen disclosed no abnormalities."

Mar 1, 1992

By F. J. Palumbo

Effective recycling or disposal of flue dusts is a continuing problem for copper, brass, and bronze smelters. Over 300,000 short tons (st) of dust is generated annually by U.S. secondary copper, brass, and bronze smelters. The Bureau of Mines has developed an alkaline leach method for recovering metal values from copper converter flue dust containing zinc, tin, lead, and copper. The dust was leached with a hot solution of ammonium chloride and ammonium hydroxide to solubilize ZnO. All of the tin (as Sn02) and the metallic copper, lead, and zinc, as well as possible insoluble compounds of each, report to the residue. Dissolved copper and lead salts are removed from the leachate by cementation with granular zinc. Zinc oxide is precipitated by diluting the leachate with water. The tin-rich (9.8 pct) residue has a ready market. The cement product is recyclable to the smelting operation. The ZnO is at least 97 pct pure and has potential marketability.

Jan 1, 1985

By Fred Kissell

The Bureau of Mines has developed the shearer-clearer--a new type of dust control system for longwall shearers. The system partitions the airflow around the shearer into a clean split and a contaminated split. The dust cloud is confined to the vicinity of the coal face, while the shearer operators remain in the clean split on the gob side of the machine. The shearer-clearer operates on the principle that each water spray moves air like a small fan and can be positioned to direct the dusty air towards the face. The hardware is inexpensive and can be installed in a single shift. It consists of several strategically mounted water sprays and one or more passive barriers. Laboratory testing indicates reductions 1n shearer operator dust exposure as high as 97 pct. Preliminary results from an underground demonstration in one mine also indicate that considerable dust reductions at the shearer may be obtained. In conjunction with the development of the shearer-clearer, dust surveys were conducted in three other mines to determine if some shearer spray systems currently in use partition the flow in a manner similar to the shearer-clearer, and if so, whether this partially accounts for markedly cleaner conditions on some longwalls. Results from these surveys indicate this to be the case. A feature of the cleaner longwalls was a downwind orientation of their water sprays, which is a key element of the shearer-clearer system. The shearer-clearer system described in this report was designed for an Eickhoff EDW 300 shearer working a 7-foot coal seam. The testing to date has concentrated on cutting directions counter to the primary airflow. The development effort continues for different mining equipment and conditions. It is expected that different systems will be required to accommodate the range of conditions occurring underground. Application of the system presented here to conditions different than those described is not likely to produce the same results.

Jan 1, 1981

By Andrew Cecala

Miner?s exposure to dust remains a top concern among regulatory agencies, particularly at production facilities with high levels of silica. This respirable dust is present in almost all operations and is a direct cause of the deadly disease silicosis. Silica is one of the most abundant minerals on Earth and is a threat at all operations, especial-ly granite and sand and gravel facilities. The National Institute for Occupational Safety and Health continues to analyze silica?s threat. The institute?s research indicates that heavy-equipment operators have an increased risk to dust exposure, especially when drilling or breaking rock, even when working from an enclosed cab. However, there are methods to reduce an operator?s exposure further, according to recent NIOSH research, which is detailed in its report, Improving Air Quality in Enclosed Caps with Uni-Directional Filtration/ Pressurization System. NIOSH indicates that when surface mining equipment is new, the operator?s dust exposure is normally at accept-able levels. As the equipment ages and components such as gaskets and seals deteriorate, the level of protection can degrade to a point where it is no longer acceptable. However, the institute indicates that at least two critical factors necessary for an effective system.

Jan 1, 2009

By L. Y. Sadler

The Bureau of Mines conducted a study Lo determine the loss in weight of silica (Si02) volatilization from low-alumina (A1203) refractories used as hot face liner materials in such process equipment as coal gasifiers, synthesis gas transfer lines, and ammonia plant secondary re-formers. Small specimens of 80-and 40-pct-A1203 brick and 95-pct-SiO2 brick were exposed to steam in high-pressure furnaces at pressures of up to 1,000 psig and temperatures up to 1,400° C for periods ranging up to 120 h. Weight losses from the 40-pct-A1203 brick after 40 h of exposure were highest, 2.75 pet at 1,400° C and 1,000 psig. The rate of weight loss had dropped to near zero after 80 h of exposure at all temperatures. No relationship between total silica content of the specimen and weight loss could be established nor did scanning electron microscopic examination of the specimens before and after exposure identify specific regions (e.g., surface) suffering a disproportionate share of the silica loss. It was concluded that minor silica volatilization is likely to occur, if at all, at temperatures of less than 1,000° C and pressures below 1,000 psig, and that low-alumina refractories should be used as dry-ash coal gasifier hot face linings.

Jan 1, 1986

By Curtis D. Edgerton

The Pittsburgh Mine Map Repository of the Bureau of Mines serves as a basic reference file for the archival preservation of mine map data of mines east of the Mississippi River. About 22,000 of an estimated 500,000 available mine maps have been microfilmed A computerized index serves as the mechanism for retrieval of any microfilmed mine map. The operation, equipment, and index are described in the report.

Jan 1, 1974

By L. B. Berger

This information circular is a revision of I.C. 7238, Danger from Carbon Monoxide in the Home, by L. B. Berger and H. H. Schrenk, issued in April 1943. Each winter brings its toll of deaths and serious accidents from the deadly gas, carbon monoxide. Newspapers carry warnings to the public of the, dangers of this gas, and frequent news items report the finding of persons dead at unconscious from the effects of carbon monoxide, yet these accidents continue. Either these warnings are not read, or they are unheeded by people who feel that, "It can't happen to me." It can happen to you carbon monoxide is no respecter of persons.

Jan 1, 1954

By Richard V. Ageton

Compressed- air blowers are frequently used both in large and small metal ines , not only as an aid to ventilation , but in some mines as a substitute for an dequate ventilation system . As a temporary fixture , blowers have their uses , but hey should never be used in lieu of a permanent ventilation system. A number Probably the most common error made in placing dependence on compressed- air lowers as an aid to underground ventilation is the tendency to over- rate their cooling efficiency . It is a very common but natural error to assume that compressed air which issues freely from a blower is of the same temperature as the compressed air which issues freely from the exhaust port of a rock-drilling machine . of readings were taken in different mines of the temperature of the rock- drill exhaust , of the compressed air flowing from the blowers , and of the surrounding air In both cases . In general , the temperature of the rock- drill exhaust was from 10 to 30 degrees below that of the surrounding air , in many instances being slightly below freezing , 32° F . The average temperature for a number of compressed-air lowers and for the mine air surrounding them is shown in Table I.

Jan 1, 1922