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By A. Dale Marcy, Pamela L. Drake

Workers who perform routine welding tasks are potentially exposed to fume that may contain manganese. Manganese may cause respiratory problems and is implicated in causing the occurrence of Parkinson-like symptoms. In this study, a field colorimetric method for extracting and measuring manganese in welding fume was developed. The method uses ultrasonic extraction with an acidic hydrogen peroxide solution to extract welding fume collected on polyvinyl chloride filters. Commercially available pre-packaged reagents are used to produce a colored solution, created by a reaction of manganese(II) with 1-(2-pyridylazo)-2-naphthol. Absorbance measurements are then made using a portable spectrophotometer. The method detection limit and limit of quantification (LOQ) were 5.2 mg filter-1 and 17 mg filter-1, respectively, with a dynamic range up to 400 mg filter-1. When the results are above the LOQ for the colorimetric method, the manganese masses are equivalent to those measured by the International Organization for Standardization Method 15202-2, which employs a strong acid digestion and analysis using inductively coupled plasma-optical emission spectrometry.

By J. E. Chilton, C. R. Carpenter

The U.S. Bureau of Mines has developed an intrinsically safe carbon monoxide (CO) monitoring system for mines by coupling a fiber-optic data telemetry (FODT) system with a prototype electro- chemical CO monitor. The CO monitoring system can be used in a coal mine as one component of an early fire warning system. This system may be used in belt haulage entries when the entries are used for supplying ventilation air to working places. The FODT accepts a 0.1- to 1.1-V analog signal from the monitor and converts it to pulses (0 to 5 V) at frequencies from 1.1 to 11 kHz that drive a light- emitting diode (LED). An electrically nonconducting fiber-optic cable carries the LED signal to a remote receiver. The receiver analyzes the incoming light signal and displays the measured CO concentration in parts per million. This report discusses the performance of the FODT system and characteristics of the CO monitor such as response times, linearity, and temperature and pressure effects.

Jan 1, 1992

By G. S. Scott

The flammability of trichloroethylene vapors in air has been determined in a 7-inch cyclindrical vessel. Saturated flammable mixtures were formed with air at atmospheric pressure between 30° C (86° F) and 82° C (180° F); the trichloroethylene concentrations at these temperatures are 12.5 (lower) and 90 (upper) volume-percent, respectively. Further study is necessary to assess the effects of different variables on the flammability of this material. INTRODUCTION Trichloroethylene (TCE) (ClHC = CCl2), sold under various trade names (Blacosolv, Perm-A-Clor, Tri, Triad, Triclene, Trivec, Tromex, Vapoclean, Vapoclor, Westrosol, etc.), is an important industrial chemical. A summary of its physical and chemical properties is given in table 1. It is used to degrease metals, leather, and textiles, to extract residual oils from vegetable oil cakes, for dry cleaning, and in soap. It is a powerful solvent for fats, resins, bitumens, rubber, sulfur, and phosphorus. Several explosions in which trichloroethylene was involved prompted an investigation by the Bureau of Mines to determine the conditions under which such accidents can occur.

Jan 1, 1963

Provide the U.S. mining industry with a user friendly computer program to calculate stresses in underground coal mines in order to improve safety conditions for mine workers. Capabilities of MULSIM/NL MULSIM/NL (multiple seams, nonlinear) is a three-dimensional boundary-element method (BEM) program developed at the U.S. Bureau of Mines for stress and displacement analysis of coal mines. It can analyze one or two parallel seams that can have any orientation with respect to the Earth's surface. Three main new features distinguish MULSIM/NL from its predecessors: (1) non¬linear material models, (2) multiple mining steps, and (3) energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material: (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardening, (5) strain hardening, and (6) linear elastic for gob. The multiple mining step capability enables the user to efficiently simulate a changing mine geometry. Finally, MULSIM/ NL computes energy release rate due to mining using the most recent concepts advanced by Salamon.

Jan 1, 1993

By A. T. Iannacchione

Underground stone mining represents an emerging sector for the U.S. mining industry. As this expansion takes mines under deeper cover and as more efficient mining methods are utilized, adequate stone pillar design methods will become more important. It is the purpose of this paper to examine current design practices and to discuss issues for safe mine layouts so that a rational first approach towards balancing the demands for increased production can be weighed against increased risk to worker safety from rib instabilities and pillar failures. Seventy-two stone mine pillar designs were examined. Pillars with width-to- height ratios below 1.5 and subjected to excessive stress levels appear more likely to fail. When width-to- height ratios fall below 1 .O, defects in the pillars, such as through-going discontinuities, can have a significant influence on stability. Discontinuity persistence, dip, material properties, and orientation are important factors controlling pillar strength. The influence of discontinuity dip, a characteristic easily identified in the field, was examined so that its presence could be accounted for in developing generalized guidelines for pillar design.

By Oliver Bowles

"The American Consul at Guatemala City reports that the Guatemala Marble Mining Company is preparing to operate a marble quarry about 13 miles from the railroad station of Zacapa, which station is a little over 100 miles from Puerto Barrios, the nearest port from which the product may be shipped. The deposit is extensive, and though somewhat broken up in places, great quantities of sound marble are available. It is claimed that the marble is equal in quality to the best product of the Italian Carrara quarries.Access to the quarry by rail is obtained by a spur track of the International Railways of Central America (Ferrocarril Internacional de Centro America) from Marmol, 3 miles south of Zacapa. This spur is about 5 miles long and terminates at the foot of the mountains. A double-track incline cable-way 2000 feet in length has been constructed to bring the marble down the mountain. From the top of the incline to the quarry there is a railway six miles in length over which the rock will be hauled by two side-geared Shay locomotives."

Mar 1, 1920

By E. C. Lane

"INTRODUCTION This is the fourth in a series of reports on properties of commercial motor fuels, made in accordance with a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the Department of the Interior. The first report gave data on motor gasolines sold during the winter of 1935-36 3/. The second resort gave the same data for motor gasolines sold during the summer of 1936 4/. The third report of the series gave the same data for motor gasolines sold during the winter of 1936-37 5/.This report covers 63 brands of gasoline represented by 1,136 samples excluding the Pacific Coast. Those from the Pacific Coast were averaged by the Pacific Coast technical group before being submitted and are published exactly as they were submitted. In some areas reports were received from five or six companies on the same brands of gasoline, whereas in other areas only one company reported on a brand. Thus, it can be seen that some of the data are more representative than others."

Dec 1, 1937

By H. B. Humphrey, J. J. Forbes

"In accident prevention, a study of statistical data is necessary to determine primary causes of accidents to devise means to eliminate causes at the original sources. Explosions in coal mines of the United States during the 10 years ending December 31, 1931, ranked third in the causes of fatal accidents; they constituted 16.2 per cent of all fatal accidents in bituminous mines and 8.4 per cent of all fatal accidents in anthracite mines. A study of coal-mine explosions in Pennsylvania, with approximately 160,000 men employed in anthracite mines and about 145,000 in bituminous mines or about 205,000 out of -the approximately 525,000 men employed in all coal mines of the United States, should give information of value to all persons endeavoring to reduce or eliminate coal-mine explosions. This circular reviews explosions of gas or dust or of both in the coal mines of Pennsylvania to show the hazard of gas and dust, to point out the influence of certain factors in causing explosions, and to emphasize the efficacy of explosion-preventive measures.The data published annually by the State Department of Mines and of the United States Bureau of Mines were used in compiling the tables of explosions. Through the cooperation of W. H. Glasgow, secretary, Department of Mines of Pennsylvania, and his assistants, many doubtful cases were clarified, so that as far as recorded the history is comparatively complete. Figures used in compiling some of the tables were furnished by W. W. Adams, chief statistician, demographical division, United States Bureau of Mines.Anthracite in the Wyoming Basin of Pennsylvania was used locally by gunsmiths in 1755, by blacksmiths in 1769, and as domestic fuel in 1808.Mining and shipments developed slowly between 1806 and 1812, but more rapidly after that.Early mining along the outcrops gave essentially no trouble from gas, but by 1870, when State inspection was established, explosions were frequent; ventilation was crude and accumulations of gas were generally ""brushed"" or burned out.Table 1 lists 1,232 ignitions and explosions of gas in anthracite mines from 1870 to 1932, inclusive, every one of which was accompanied by loss of life. Some details are given of 110 representative cases in which five or more lives were lost or in which it appeared that some violence was present.During the period 1870 to 1932, inclusive, gas explosions caused 2,213 fatalities, or an average of about two deaths for each ignition or explosion. Records are not available as to the number injured in these and in other explosions where no deaths occurred, but from a study of explosion reports it appears probable that the number injured exceeds the number killed. In the 110 cases described, 599 were killed and 294 were injured. As shown in Table 2, fatalities from gas explosions averaged 8.3 percent of the total fatalities in Pennsylvania anthracite mines from 1870 to 1931, varying from 6.0 percent in 1931 to 13.1 percent in 1927."

May 1, 1933

By J. M. Harrington, C. W. Owings

"The transportation of explosives, and especially their distribution from the supply magazines of the manufacturers or dealers to the mines, quarries, or other points where they are to be used, by means of horse-drawn vehicles is an old-time practice, and the records of accidents of the past show this to have been a hazardous undertaking requiring for safety the taking of many precautions not required in the transportation of other merchandise.Displacement of the horse-drawn vehicle by the motor vehicle for the transportation of explosives is increasing rapidly. A consideration of the facts that the vehicle is operated by an explosion engine, using easily vaporized liquid fuel; that the charges in the engine are fired and the vehicle lighted by electricity; and that the vehicle, being operated insulated from the ground, may accumulate static charges led to the conclusion that new hazards are being introduced into the transportation of explosives through the use of motor-operate& vehicles, and that therefore additional special precautions must be taken against these additional hazards.That accidents have already occurred in this use of motor-vehicle transportation is evidenced from the following examples:Recently in California a driver loaded a box of granular powder in the rear of an automobile truck and a box of electric detonators in the front. Suddenly, while traveling along a highway, the explosives detonated, demolished the truck, and blew the body of the driver into small pieces. No evidence was left to show the cause of the explosion, but it is assumed that a jar or other means caused the detonators to fire, and that they in turn detonated the explosive. It should be recognized that it is unsafe to transport detonators and explosives in the same compartment, and this rule should be strictly enforced. At present this rule appears to be either unknown or, at least, frequently ignored.There are usually so many possible causes of ignition or detonation of a truck load of explosives that it is often impossible to state definitely the exact cause in a given case. This is well illustrated in the following account of an accident: A trucking company was hired to haul a truck load of explosives about 200 miles. The driver had had experience in driving trucks of explosives, and it was stated that he inspected the truck carefully before leaving the garage. Eighty 50-pound boxes of explosive were placed in tiers on each side of the truck and 265 25-pound kegs of black blasting powder were placed in the center of the truck. The boxes were placed flat and the kegs were placed on end, arranged in tiers. While the truck was being driven along the highway there was a muffled explosion. When some men, who were about a quarter of a mile away, arrived at the scene the truck was in flames and they could get no nearer than 100 feet. The driver was sitting in his seat and had apparently been killed instantly either by shock or fumes. When the flames were finally quenched, the driver's body was recovered, badly charred. It was, found that several boxes of explosives had been thrown about 40 feet by the initial explosion but were uninjured. A total of half a ton of dynamite was recovered. The cover to the gasoline tank could not be found."

Aug 1, 1930

By A. E. Wells

A critical study of the wet Thiogen process for extracting sulphur from the smoke of smelters is one of several investigations related to the general smelter-smoke problem that are being conducted under the direction of the Bureau of Mines. Part of the work done in the pyrometallurgical section of the cooperative metallurgical exhibit of the Bureau of Mines at the Panama-Pacific International Exposition during 1915 related to this investigation, and at the expiration of the exposition, the work was continued in the labora- tories of the Bureau of Mines in the Hearst Memorial Mining Building of the University of California, Berkeley, Cal., where a mining experiment station of the bureau has been established under the cooperative agreement with the University of California. Early in the spring of 1915, when plans were being made to co- operate with several metallurgical interests, the Thiogen Co. proposed to the Bureau of Mines that, along with the studies of various pro- posed methods for eliminating sulphur dioxide from smelter smoke, there should be included a study of the wet Thiogen process. In the study as outlined it was proposed to determine whether it would be technically and commercially feasible to use the, process for the recovery of elemental sulphur from the sulphur dioxide in waste smelter gases. Although there had been no large-scale work with the process, either in the laboratory or at a smelter, representatives of the metallur- gical and mining industry had shown considerable interest in the proposed method, and the desire had been expressed that a better knowledge of the possibilities of the process should be obtained. Thus, cooperation with the Thiogen Co. seemed justified by the in- terests of the metallurgical industry, and by the conservation promised by the recovery of a product of market value from what is otherwise a waste, and in some instances a serious nuisance. In accepting the responsibility for directing this investigation, the officials of the Bureau of Mines were necessarily free to conduct the work in the manner they considered necessary to determine the facts. It was also understood that any information obtained was to be made available to all who might be interested and might be printed in a Bureau of Mines report. To cover the cost of laboratory equipment and supplies, and the payment of salaries of assistants, other than Bureau of Mines employees, the Thiogen Co. in May, 1915, deposited with the cooperative metallurgical exhibit fund a sum considered sufficient to warrant starting the laboratory investi- gation. The origin and organization of this fund has been described by Clevenger and the author." In outlining the program for this investigation it was hoped that ultimately a small complete plant would be erected and the investi- gation center around the operation of the plant. However, pre- liminary to the erection of the plant, a laboratory study of the proc- ess was considered necessary, as the technical features of the process could be determined, it was believed, as satisfactorily on a smaller scale as on the scale first proposed. However, it was realized at the time that it would not be possible to determine so satisfactorily or definitely the commercial possibilities of the process on the scale of work adopted as in the larger operating plant. With this fact in mind it was planned that, if the study of the technical features on a laboratory scale gave sufficient promise of the process being commer- cially feasible, an operating unit should, if possible, be constructed later, and that more definite information concerning the commercial prospects should be determined. The investigations were started in June, 1915. In June and July work was confined entirely to small-scale laboratory tests, in which a careful study of the chemical reactions involved was made. In August, tests on a larger scale were started, and these were con- tinued until December, small-scale tests being made at the same time. On December 1, 1915, all work on the Thiogen process was discon- tinued temporarily, as the close of the exposition necessitated moving the laboratories. Work on the Thiogen process was started again in January, 1916, in the laboratories of the new mining experiment sta- tion at Berkeley, Cal., and was continued during the spring of 1916 until a point was reached where it was felt that the essential parts of the process had been carefully covered, and that some definite state- ments concerning the technical features and possibilities of the process, as given in this report, were warranted.

Jan 1, 1917

By Joseph H. White

In its investigations looking to the improvement of health condi- tions and the increase of efficiency in the mining industry, the Bureau of Mines, in cooperation with the Bureau of Public Health, is studying sanitary conditions in and about mines with the intent of pointing out how those conditions that are a menace to the health of the miner may be most efficiently removed or remedied. An out- line of sanitary betterment work at mining villages in the Birming- ham district of Alabama has already been published by the bureau," and in this bulletin are presented suggestions on the planning of mining towns and the construction of miners' houses. The bulletin does not pretend to be a treatise on the so-called "housing problem," and mentions sociologic issues only incidentally. It is assumed that the influence of proper shelter on health is understood and that not a lack of appreciation so much as a lack of knowledge of the best remedies is responsible for many of the undesirable conditions that exist at mining towns. The purpose of this bulletin is to supply facts on the building of well-lighted, well- ventilated, warm, attractive, and economical houses for miners, these houses being assumed to be units of an industrial village or town the building and management of which are under the control of a corporation, so that special conditions hold which do not apply to houses built and owned by individual miners. From this it is not to be inferred that the company-controlled town is the best system or the only one in vogue. The discussion of this side of the subject in all its phases is too involved to be included in this paper. One element in favor of the company-controlled town is its possible immediate responsiveness. Hence this assumption. Also the assumption is made that a-new isolated town is being built, and hence the selection of the site, the arrangement of the streets, and the situation of the houses are discussed before the house itself is treated, for one of the most important factors in obtaining an economical sanitary house is a well-selected town site. Many of the suggestions, however, may be applied in improving conditions in existing towns, in building new houses in old towns, or in repairing old houses. Emphasis must be laid on the fact that as a rule a mining village has a shorter life than a manufacturing town. Economy is emphasized frequently because the discussion is predi- cated upon the assumption that the miner himself is to pay for all that he gets. House rent will doubtless be expected to bring in a reasonable return on all money invested in streets, sidewalks, water supply, sewer system, and houses; in other words, the town is to be run on a business and not on a paternal or charitable basis. "Fair and reasonable" precludes, of course, the idea of excessive returns. Some companies do not consider it good policy to realize as high a rate of interest as an independent realty company would be war- ranted in realizing. Under some circumstances part of the town improvements might be charged as "expense of the industry," that is, to the consumer. The isolation of a mining town introduces a unique responsibility. As the miners are practically obliged to rent the company houses, the officials of the company ought to scrutinize all expenditures in- volved so that house rent may be reduced to a minimum. In a way the town builders are placed in the position of trustees. They deter- mine, within certain limits, what proportion of a man's wages shall be spent on house rent. This consideration should restrain fanciful and unnecessarily expensive building; the other extreme should like- wise be avoided. True economy should be distinguished from cheap- ness. Ugly, insanitary, uncomfortable shacks should not be built even if, because of their cheapness, there is a demand for them from tenants. The obligation of the industry to society as a whole as well us to the tenant ought to forbid this. A cheerful, strong, healthy, virile race will not rise out of the filth and squalor of cheap hovels. An insanitary environment often does its damage slowly and silently; vitiated air does not, like mine gas, announce its deadly work by an explosion. As Talbot⚫ says: Health depends in part on freedom from infection. The probability of obtain- ing that freedom will be greatly increased by maintaining the body at a high state of vigor, or "vitality," as it is popularly called. This implies the promo- tion of all agencies which have to do with the physical well-being as well as with the control of sources of infection. Many men realize that in building houses for their workmen they are invested with a peculiar responsibility that must be wielded wisely, and in large developments they call into consultation the land- scape architect, the sanitary engineer, and the building architect, as well as the mining engineer.

Jan 1, 1914

By L. C. IlsLey

A preliminary investigation has recently been made by the U. S. Bureau of Mines to determine whether or not the ordinary mine- type telephone is entirely safe in gaseous atmospheres . Two well known makes of mine- type phones were purchased for this investigation . It is not conceivable that the current necessary for talking over telephones could ignite gas . However , such phones are provided with efficient magnetos , and it was believed that danger might result from the ringing of the magneto . Again , while this type of phone has been designed to have a certain measure of dust and moisture tightness , evidently it has not been designed as an explosion- proof device . either with regard to cover joints and fastenings or strength of castings . Therefore , the problem was simplified . First it was assumed that owing to the construction of the telephones the gas would penetrate into their interior , and the question was to ascertain whether or not the gas would be ignited from the operation of the magneto .

Jan 1, 1922

By A. B. Hooker, L. C. IlsLey

In lare-scal e blasting, it is customary to fire me.l'\Y shot.!:l simu1. taneously. The electric !atonators ara usually conneced in seies, ard are fired either from a power circuit or :from a blasting ma.chine with large capacity, operated by hand. "!hen :'::ri111; with a blasting ca.chine, trouble with missed shots has been freqi.,.ently e>:pert0nced.. Unit1:i:' thes ,:::rcu:ns tances, the shots that fail to fire are often a gr"up in the t.:E"nter r,f t>e series, Various explaz,.a.tions hs.ve been given as to the cause of the failurs. Tis paper covers a few tests made cy the electrical section of tl:.e Dti..'t'cau. cf Mines, wh;.r.;h may be helpful in understanding the -probable cuse of tl1e misfiring of c.:anter shots, Wh3tever th9 source ot the firir. current generator, magneto, or batter, the CUl"rent delivered th:·01.1.gh a shot-f:?·ing circu.it is determined by t.ae total resistance of ,;he clrcili +.; c:1nd all cure:it leaving th9 p,si tive terminal must return to tre negative te1-minal. If a. metallic circuit is well i1,.sul.:tted, praeti­ccl. l;1 a.ll of the t.'Urrent keepo within the circu.it; but in a. shot-!11·.irig ci.rc1li t, Nhere the ·.vires f:ll·e often 1n c.c,i.cact with the eru:"!ih as i11 wet holer., end whero the ins".lla.tion of the leg wires :i. inadecpa.te to prc·,ent lea.l.tage, the current ma.v tu.e v a.r ious pa the: thro-.. .. gh the nr r. earth.

Aug 1, 1922

By J. A. Woolf, E. S. Leaver

"So much has been written on the ore genesis of the Comstock Lode that it is sufficient here to describe the original ores as consisting chiefly of quartz and some calcite. In places .a considerable amount of pyrite appears. There are also minor amounts of galena, chalcopyrite, and sphalerite. The chief silver minerals are argentite, stephanite, and polybasite. Most of the gold is native.A composite analysis of the ore; obtained by averaging the results from the early workings of several mines, is shown in Table 1.The history of the milling of Comstock ores from the Sixties to date would call for a review of the development of precious-metal metallurgy. However, a brief outline of the methods employed will give a better basis for studying the difficulties that are to be expected in the final retreatment of the remaining residues.In the earliest days amalgamation was accepted as the main recovery method. The large tonnage of good-grade ore from the Comstock Lode attracted the best metal¬lurgical talent of the time, and developed there the highest skill in the art of amalgamation, including the auxiliary chemical preparation of the ores and the mechanical operation. In this work 0.5 to 6.0 pounds of mercury was used per ton of ore. The mercury loss probably averaged about 2.5 pounds per ton of ore treated.The better grade of tailings from the ores milled were impounded, often near the works. In many cases the same tailings were reworked several times before they entered the main outflow waste stream that had its course down Seven Mile Canyon to the Carson River. Following the water course down the canyon the tailings were re-impounded, and, as metallurgy advanced, new plants were erected to again re-treat them. The most successful of these plants used forms of amalgamation, chlorination, and cyanide methods of recovery. To the tailings from the re-treatment plants, smaller tonnages of untreated tailings produced by milling lower-grade ore are continually added.Along the stream bed down the canyon a series of blanket runways were constructed, and each was independently operated for years by one or more men. All, or the heavier portion of the stream flow was run over the blankets; in this way much of the heavier concentrate, mostly sulphides and mercury products, was reclaimed.All of the residues finally entered the run-off flow along with the sewage from Virginia City and waste from the gas works, saw mills, and stables. As the accumulation along the bed of the Carson River became a nuisance, the lighter and better grade of tailings was impounded on the banks of the river. This accounts for the large dumps locally known as ""Douglas tailings."""

Jul 1, 1928

By E. J. Ostrowski

The Bureau of Mines experimental blast furnace, Bruceton, Pa., was operated to determine the feasibility of replacing part of the burden coke requirements with solid fuels injected directly into the smelting zone. This report describes preliminary experiments and information resulting from such an interchange. These experiments were made on an all-sinter burden, using two parts sinter to one part fuel. Anthracite fines were injected intermittently into the smelting zone of the furnace by compressed air through auxiliary tuyeres. The interval between injection periods ranged from 5 to 15 minutes. A maximum of 28 percent of the stock column coke bur-den was replaced. This percentage replacement caused furnace malfunction, but the overall percentage of these experiments indicated that 20 to 24 percent of the coke requirements could be replaced in this way. The metallurgical coke consumption was decreased by as much as 377 pounds (25.3 percent) per ton of pig metal produced. Buckwheat anthracite No.4 was used in this experiment; however, such solids as bituminous coal or coke fines also could be used. The frequency as well as the quantity of solid fuel injected has a direct bearing on furnace performance.

Jan 1, 1960

By John B. Shutack

In an effort to improve the performance of the explosive-anchored rock bolt, the Bureau of Mines studied the effect of the detonation velocity of the explosive and type of charge (linear or nonlinear) on the fracturing tendency of the anchor tube. Also, different types of tubing were compared to determine the one most suitable for use as an anchor tube. The Bruceton up-and-down method was applied in tests in which steel shooting blocks having boreholes ranging from 1-3/8 to 2-1/8 inches in diameter were used. Of the four types of tubing evaluated, a welded A-178 tubing that was drawn over a mandrel and renormalized gave the most promising results. The A-179 seamless tubing that is normally used with the explosive bolt was the most inferior. Both types, however, gave significantly better anchorage than the conventional shell when tested in both laboratory and underground experiments. Within the range of velocities studied (5,000 to 7,000 m/sec), the type of explosive showed no significant effect on anchor-tube performance. In general; linear explosive charges provided better anchorage than nonlinear charges.

Jan 1, 1968

By A. F. Colombo

The differences in starch demands that occur between ore types subjected to the anionic flotation of calcium-activated gangue and the range of residual starch contents expected to give the best metallurgical response were evaluated on a batch and pilot plant basis. A phenol-sulfuric acid procedure was used to determine the residual starch contents in the iron ore slurries. Three pilot plant campaigns on samples from a group of orebodies located on the Marquette Range, Michigan, showed that in the rougher flotation pulp, a residual carbohydrate range of 25 to 100 ppm, which is equivalent to a 0.5 lb/short ton spread, yielded optimum results. Concentrates assaying at least 65 percent Fe and less than 6.0 percent Si02 and containing more than 80 per-cent of the recoverable iron were obtained. Both batch and continuous research indicated that starch adsorption is calcium modulated and relatively unaffected by the fatty acid additions employed. Residual starch level is not a critical control factor, but the addition must be adjusted to about 25 to 50 ppm residual starch and kept in this range for most effective utilization of the added tapioca flour.

Jan 1, 1972

By K. O. Bennington

The thermodynamic properties of pollucite [(Cs0.650Na0.185Rb0.028)(AlSi2) (05.8630H0.137)?0.19H201 were determined by the Bureau of Mines in collaboration with the Argonne National Laboratory. The standard enthalpy of formation determined by hydrofluoric acid calorimetry is ?Hf°298 = -3,098.52 ±3.63 kJ mol-1. The standard enthalpy of formation from the oxides is ?H298 (from oxides) = -209.50 ±2.38 kJ mol-1. Low-temperature heat capacities were determined by adiabatic calorimetry from 5.0 to 306.1 K. The derived standard entropy is S°298 = 207.24 ±0.43 J mol-1k-1. Enthalpy increments above 300 K were measured by copper-block drop calorimetry from 349 to 674 K. Various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of measurements. Standard enthalpies of formation and Gibbs energies of formation are given as functions of temperature. The Gibbs energy of formation is ?Gf°298 = -2,919.9 W mol-1

Jan 1, 1983

By W. A. Selvig

The experiments described herein were made at the request of Committee D-5, on Coal and Coke, American is n Society for Testing Materials, in order to obtain data as to the probable contamination of laboratory samples of coke Then pulverized to pass a No. 63 sieve of tine U. S. Standard Sieve Series2 by methods other than by ball-mills or hard-steel diamond mortars, which methods are specified-in the standard methods of that Society.3 After pulverizing, representative samples were analyzed by the Bureau of Mines at Pittsburgh for ash content to detect any contamination of the samples by the pulverizing apparatus. Preparation of Core Samples for Tests. Two samples of 48-hour beehive coke (Continental and Leisenring) made from Pittsburgh coal were selected for the tests. These cokes were crushed approximately to No. 10 sieve size, by first passing through a jaw crusher and then through a, roll crusher. The crushed coke was then carefully mixed and riffled into portions of about 800 grams each, and sent to three cooperating laboratories for grinding, through a No. 60 sieve. Size tests on these samples shoved the fineness to be as follows: [ ]

Jan 1, 1925

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

7. Development of Acoustic Seal Checking System The acoustic approach was shown in Section 4 of this report to be the most promising concept for checking the seals. This section describes the development of this concept into a working hardware system to be used later in the field test program. This development effort included: (1) Theoretical analysis of the acoustic behavior in the mine using acoustic modeling- techniques. (2) Experimental determination of acoustic patterns in mine passages. (3) Refinement of the theoretical model. (4) Verification of final theoretical predictions in the quarter-scale laboratory model of a mine passage and seal. (5) Development of system specifications. (6) Development of the Acoustic Prototype Seal Checking System. 7. 1 Analysis of the Acoustic Seal Checker Concept The acoustic seal checker concept is based on a model which combines corridor acoustics and hole transmission theory. The idealized model for the mine sealing application is shown schematically in Figure 66. A high intensity acoustic- source is located in a corridor at a, position adjacent to the location to be sealed. The acoustic signal transmitted through the seal is monitored by a microphone pick-up placed on the opposite side.

Jan 1, 1973