Search Documents

By GEORGE S. POPE

This bulletin is the third of a series a showing the results of ment purchases of coal according to specifications as to its quality and giving typical forms of proposals for supplying coal and general information relating to government coal purchases . Numerous calls for authentic information concerning the purchase of coal according to its heat value attest a growing interest in the subject. Many of the commodities of life have long been purchased according to specifications requiring chemical or physical tests , or both, to determine whether the material delivered meets the requirements , the price to be paid depending on the results of the tests . Until recent years coal consumers purchased coal merely on the statement of the dealer as to its quality , relying on his integrity and on the reputation of the mine or district from which the coal was obtained. It is surprising that the important question whether value was being received for the money expended was not sooner seriously considered . The purchase of coal by specification is an important step toward the conservation of our national mineral resources , for it results in an increased use of the lower grades of coal. The poorer coals find a market by competing with the better grades , not as to the price per ton but as to the cost of an equal number of heat units. This paper gives in detail the results of government purchases of coal for the fiscal year 1908–9 and the list of contracts with abstracts of specifications for the fiscal year 1909–10 , and summarizes the information on this subject obtained by the Survey. It is hoped that this information will promote a better understanding of the specification method of purchasing coal and furnish data valuable alike to coal dealers and coal consumers , so that equitable contracts can be more readily made.

Jan 1, 1910

By Lyman C. Hitchcock

The objective of this program was to determine the minimum luminance requirements for underground coal mining work from the working face to the first transfer point. The resulting data encompasses 114 visual tasks from conventional continuous and longwall mining methods representing the salient visual tasks found in the jobs listed. Cutter Operator Roof Bolter Face Drill Operator Airdox Operator Longwall Jackman Shuttle Car Operator Loader Operator Shot Fireman Continuous Miner Operator Longwall Head Conveyor Operator Longwall Tail Conveyor Operator

Jan 1, 1973

By John E. Pahlman

The Bureau of Mines investigated the feasibility of removing heavy metals from mineral-process waste streams by precipitation with lignochemicals and humic acids. Lignochemicals are by products from the paper industry, while humic acids are obtained by caustic treatment of peat, subbituminous coal, and lignite. These high-molecular-weight organic materials have many functional groups, which can coordinate and form innercomplex salts with heavy metals that are crystalline precipitates. Filtering of a humic-acid-or lignochemical-treated solution or waste stream containing these precipitates removes the heavy metal sequstrates. Tests were conducted with two lignochemical samples, three humic acid samples, lime (CaO), and sodium hydroxide (NaOH) in which increasing amounts of these additives were reacted with 50 mL of solution containing Fe3+ , Al3+, Cr3+, Pb2+, Cu2+, Cd2+, Zn2+, Co2+, Ni2+, Mn2+, and Hg1+. At the appropriate pH, greater than 90-and 99-pct removal was achieved for these 11 heavy metal ions from the 10-and lOO-ppm solutions, respectively, using lignochemicals and humic acids. Removal efficienC)' with these organic materials is better than that with CaO, especially for the more toxic ions, Hg1+, Cd2+, and Pb2+. Unlike the precipitates formed with NaOH or CaO, those with lignochemicals and humic acids are compact and noncolloidal. The volume of their sludge is sharply lower than that of the finely dispersed lime or soda precipitates; thus, their removal in settling tanks or by simple filtration is enhanced.

Jan 1, 1988

Despite modest improvements in the performance of domestic interest rates and gross national product,1 fixed investment in domestic producers' durable equipment continued to weaken during the second quarter of 1982 and declined at a 12.8 percent annual rate compared with the first quarter.2 Large declines occurred during the second quarter in expenditures on many of the major mineral-consuming industries such as aircraft, computers, agricultural and construction machinery and mining and oil field equipment. These data appear to be consistent with the low level of business investment plans for 1982 reported in the DOC's Bureau of Economic Analysis survey of expenditures on new plant and equipment.3 Domestic and foreign industrial production and mineral industry production activities continued to decline in the most recent period because of weak demand conditions (Tables 1 and 2). The U.S. mining production index declined 7.7 percent between April and June as compared with 1.2 percent for total U.S. industrial production (Table 1).

Jan 1, 1982

By E. J. Lintner, J. R. Thoenen

During the period 1937-40 and until peacetime research was superseded in 1941 by wartime activities , the junior author was engaged in studies regarding the relative efficiency of operating methods in quarries producing crushed stone for mineral aggregates . The results of some of these studies were published as reports of investigations in 1939 and 1940 ; / others were discontinued due to war demands on personnel and time . The published reports discussed the efficiency of particular quarry operations with respect to the time consumed and without reference to costs or mechanical factors . • At the time , the field data were collected for the published reports other data were collected relative to the relationship of the numerous variable factors inherent in the operation of a churn drill to the ability of the drill to produce blast holes . The churn drill is essentially a crusher and depends. for its performance upon the foot-pounds of energy it can impart to the cutting edge of its bit . The gravity stamp mill , so well-known in western gold mines , is essentially the same type of crusher . The ratio of foot- pounds necessary to crush the rock , to the total theoretical energy developed by the falling churn- drill tools , affords a good means of evaluating the efficiency of the tool . This does not include to tal over-all efficiency involving the mechanical equipment of the drill itself or its power unit .

Jan 1, 1947

By Len Blackman

The Absaroka-Beartooth Study Area is a tract of approximately 1.4 million acres of National forest land in southern Montana, part of the Greater Yellowstone Area. This study evaluated the mineral potential of four mineral terranes containing undiscovered resources in the area. The geological data is probabilistic, with estimates of the possible number: of deposits and their grades and tonnages. Possible future development scenarios range from no development to many mines, including some very large. As two thirds of the study area is within the Absaroka-Beartooth Wilderness, the future development scenarios reflect the area's mineral potential, not what we expect to see in the foreseeable future. Based on the analysis performed on these four terranes, the most likely future scenario for the study area would include the potential for two medium sized, (predominately) gold, mines, each employing a few hundred workers. There is a small chance, less than 5%, that a large Porphyry Copper or Superior Iron deposit would be discovered and be economically feasible to develop.

Jan 1, 1994

By J. W. Town

The Bureau of Mines made continuous-circuit beneficiation studies to determine the optimum conditions for concentrating phosphate minerals from the intermediate-and marginal-grade ores of the Phosphoria Formation in southeast Idaho. Intermediate-grade ore was represented by a sample from Georgetown Canyon and marginal-grade ore from the Gay mine near Fort Hall. Two flow-sheets were developed: The first involved roasting, attrition scrubbing, sizing to remove a concentrate, grinding of the oversize, des liming, and flotation; in the other flowsheet roasting was eliminated. Controlled attrition scrubbing was used to remove clay and silt-size quartz particles imbedded in the phosphate pellets without breaking the pellets. The minus 35-plus 200-mesh fraction was removed by sizing as a finished acid-grade concentrate. The plus 35-mesh material was ground in a rodmill to minus 35 mesh and recycled to the attrition scrubber. The minus 200-mesh fraction was des limed at about 800 mesh to remove clay slimes and floated with 3 to 4 pounds of emulsion per ton of feed. The aqueous fatty-acid oil emulsion consisted by weight of 3 parts No.2 diesel oil, 3 parts crude tall oil, and 0.5 part water-soluble petroleum sulfonate.

Jan 1, 1967

By A. G. Mayton

Vehicle vibration exposure has been linked to chronic back pain and low back symptoms among agricultural tractor drivers. The objectives of this study by the National Institute for Occupational Safety and Health (NIOSH) were to assess driver whole body vibration (WBV) exposures and recommend interventions to reduce the risk of back related injuries, particularly relative to vehicle jarring/jolting (the transient mechanical shock components of WBV). The methodology included collecting, from two independent samples, ?eld data and health and work history data of farm equipment operators. Data were collected during mowing, raking, baling, chiseling, tilling, and road travel for different model tractors. Spraying using a sprayer and shrub removal with a skid steer loader were also included. Based on ISO 2631 (1985), the American Conference of Governmental Industrial Hygienists, threshold limit values, presents 0.5 m/s2 as the action level recommended by the Commission of European Communities for overall weighted total RMS acceleration (vector sum for axes x, y, and z) [ACGIH, 2006. Threshold limit values and biological exposure indices. Cincinnati, OH]. WBV measured at the operator/seat interface exceeded this action level. The roughest rides and highest vector sum accelerations occurred with small utility tractor mowers (3.3 and 2.8 m/s2) and a skid steer loader (1.7 m/s2). Major ?ndings from health and work history data showed 96% of participants reported having to bend or twist their necks, although 24% reported neck symptoms. Sixty four percent of participating operators reported experiencing back symptoms (e.g., pain, aching, stiffness, etc.). Recommendations included: specifying a seat that ??better?? isolates operators from jars/jolts with new tractor purchases; maintaining the seat/seat suspension and replacing worn or damaged cushions with NIOSH tested viscoelastic foam padding; using larger diameter tires with radial ply instead of bias ply construction, particularly on small utility tractor mowers, to aid in attenuating ride ??roughness??; using a swivel seat to reduce the stress on the neck from bending or twisting; and improving efforts to educate owner/operators of the adverse effects of WBV exposures. Since the data presented in this paper were collected from two independent samples, the authors were unable to draw any correlations or etiological inferences from the study. However, results were compared and contrasted with other studies which included similar vibration measurements in agriculture.

Jan 1, 2008

To provide a flexible, low-maintenance, low-cost continuous mine air monitoring system as an alternative to conventional fixed-point, electronic monitoring systems. Background Continuous monitoring of mine air is highly desirable (and often required) not only to improve miner safety, but also to increase mine productivity. Continuous air monitoring systems can provide earl" warning of developing fires, excessive methane accumulation, reduced oxygen levels, and other developing problems in remote, inaccessible or sealed areas, and in active workings. Fixed-point, electronic systems require one Sensor for every gas to be measured at every defined monitoring location. As the number of monitoring locations increases, so does the cost, along with increases in the time required for routine maintenance and calibration of the sensor System cost also increases when monitoring locations are identified for mine areas requiring permissible electrical equipment.

Jan 1, 1988

By J. J. Jakosky, D. H. Zellers

"IntroductionThis paper is the seventh of a series describing an investigation being conducted by the Bureau of Mines on underground communication. A review of past work and results obtained has been published. The present paper deals with a study of line-radio or wired-wireless methods of communication, herein electrical energy is transmitted by metallic conductors.The use of line-radio over metallic conductors has been practiced for a number of years, and at present is being used on a large scale in long-distance carrier-current telephone and telegraph. The early work of the U. S. Army Signal Corps and the Bureau of Standards in using ordinary radio transmitting and receiving apparatus for communication over metallic conductors was been descried. Later publications describe commercial applications, and an excellent treatise and resume is given by E. Colpitts and C. B. Blackwell.Scope of ReportThis report contains (1) a discussion of the chief factors affecting carrier-current transmission, with particular reference in application to underground communication for mines; (2) a description of typical underground circuits used for power and lighting; and (3) description of apparatus used and results obtained in line-radio experiments in coal mines near Pittsburgh, with circuit diagrams, and conclusions as to power requirements and limitations for mine use."

Apr 1, 1925

By Franklin B. W. Woodbury

The Bureau of Mines, as part of its goal of helping maintain an adequate supply of minerals to meet national economic and strategic A needs, is evaluating alternative technologies to treat oxidized taconites. Since process control is an essential element in the application of these process technologies, research was performed on a prototype monitoring system utilizing a Californium-252 (252-Cf) neutron source and a thermal neutron capture-gamma ray spectra analysis method to measure the amount of iron and percent solids in process slurries. The prototype system was used to monitor the concentrate and tailing streams in a 900-lb/hr flotation pilot plant during continuous around-the-clock tests. The iron content of the process slurries was determined by measuring the total peak areas under the capture spectrum peaks at 7.626-7.632 MeV, the associated escape peaks at 7.136-7.122 and 6.626-6.612 MeV, and the iron doublets at 4.900 and 4.998 MeV. A potential method for determining the percent solids in process slurries using the 2.22 MeV hydrogen capture peak is discussed. Results of this work demonstrate a potential method for providing process control parameters using the data from thermal neutron capture-gamma ray reactions.

Jan 1, 1980

By Michael R. Yenchek

The U.S. Bureau of Mines investigated the performance of portable power cables under transient conditions. This research had a twofold purpose: (1) to define the thermal characteristics of electrically overloaded trailing cables, and (2) to conceptualize electrical protection for cables that allows maximum cable efficiency without diminishing electrical safety in underground mines. Several tasks were undertaken in support of these goals during the 3-year research effort. Overload tests ranging from 2 to 12 times rated ampacity were conducted in the Bureau's Mine Electrical Laboratory. Two thermal models of energized type G-GC trailing cables were constructed, one based on thermodynamic theory and the other using empirical data from previous Bureau load tests. The empirical model was then incorporated into an interactive computer program that can assist designers and approvers of mining machines in selecting the appropriate size trailing cable. This program can be the basis for a cable protection system that ensures that cables are not the source of fires, ignitions, burns, or explosions underground.

Jan 1, 2010

By Wm .. O. Vanderburg

This paper describing the mining practices at the Block P mine of the St. Joseph Lead Co. at Hughesville , Mont . , is one of a series of similar papers being prepared by the Bureau of Mines on mining practices , methods , and costs in the various mines of the United States .

Mar 1, 1931

By Andrew B. Cecala

The U.S. Bureau of Mines has designed and evaluated total mill ventilation systems at two different mineral processing operations. Both systems have proven very effective at reducing respirable dust levels throughout the mill in a cost-effective manner. A 25,500-cfm system installed at a clay processing mill provided approximately 10 air changes per hour. This system reduced respirable dust concentrations by approximately 40 pct throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 50,000 and 100,000 cfm of ventilation to the mill building, corresponding to 17 and 34 air changes per hour. Average mill-wide respirable dust reductions were 36 and 64 pct, respectively. Not only did these systems reduce respirable dust concentrations and increase visibility throughout the mills, they were also easy to install and required minimal maintenance. A total mill ventilation system provides a general purging of the mill air; the system should be viewed as a supplemental technique to assist other dust control systems in operation.

Jan 1, 2010

By R. O. Dannenberg

This Bureau of Mines report describes the results of research to develop a process for recovering additional beryllium from a commercial mill waste product, fluoferrate leach residue. Forty-five percent of the total beryllium in the leach residue was recovered in a beryllia product assaying over 98 pct Be0 by a process comprising (1) leaching with 1 N sulfuric acid, (2) adjusting the acidity of the leach liquor to pH 2, (3) extracting the beryllium with di-2-ethylhexyl phosphoric acid (EHPA), (4) stripping the loaded extract with sodium hydroxide solution, (5) boiling the sodium beryllate strip solution to precipitate beryllium hydroxide, and (6) calcining the beryllium hydroxide. Calculated reagent requirements per pound of Be° recovered by a proposed flowsheet were 28.1 lb sulfuric acid, 0.04 lb flocculent, 0.15 lb EHPA, 0.06 lb isodecanol (IDA), 0.22 gal kerosine, and 6.3 lb sodium hydroxide.

Jan 1, 1966

By Roy C. Bartholomae

This Bureau of Mines report presents the results of a laboratory investigation of coal cutting mechanics and noise. These experiments were performed using linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts was ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to formulate analytical models of the coal cutting forces and noise. The analytical model for coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator's position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as provide benefits to other important areas of health and safety in underground mining.

Jan 1, 1983

By H. H. Schrenk

There is a need for a method of determining benzene vapor in air which is simple and accurate and suitable for making industrial hygiene surveys. The most widely used method in this country is the Smyth modification of the Elliott and Dalton procedure. This depends on the nitration of the benzene to m-dinitrobenzene, reduction to phenylenediamine with an excess of standard titanous chloride solution, and back titration with a standard ferric ammonium sulphate solution. This method has the disadvantages of being somewhat time-consuming and cumbersome; it requires considerable apparatus, and a special modification is necessary in the presence of toluene. Recently Cook and Ficklen have published a method based on the oxidation of benzene with hydrogen peroxide in the presence of iron salts. This method requires the use of solid carbon dioxide to freeze out the benzene. The reaction Which produces the color is complex; and only approximate quantitative estimations can be made, except in a very narrow range.

Jan 1, 1935

By L. H. Banning

Recent dry-top electric smelting tests at the Northwest Electrodevelopment Experiment Station, Albany, Oreg., indicate that a high-titanium slag and a good grade of pig iron can be produced from alluvial Idaho ilmenite. A total of 120 tons of concentrates were smelted during this investigation, to yield an average of 0.5 ton of slag and 0.3 ton of pig iron per ton of ilmenite. Power consumption averaged 1,400 kv.-hr. per ton of ilmenite, at a feed rate of 400 to 500 pounds per hour, when operating at an electrical energy input of 290 to 370 kilowatts. The optimum operating voltage appeared to be 110 volts, phase-to-phase. Graphite electrode consumption averaged 15.6 pounds per ton of ilmenite smelted. Magnesite furnace refractory withstood the corrosive action of the hot metal and slag better than carbon refractory.

Jan 1, 1955

By Mark S. Sanders

This report discusses the development and testing of prototype gloves for underground mining work. An analysis of HSAC hand-finger injuries revealed three high-risk jobs: laborer, mechanic, and roof bolter. Laboratory tests of dexterity and protection were performed using six off-the-shelf gloves. Two prototype gloves were developed. Both were Kevlar-cotton blend knit gloves. One had polyvinyl "Ks" screened on the palm and fingers, and a hand pad sewn into the palm. The other prototype had the palm and fingers coated with a sol id layer of polyvinyl and had no hand pad. Field tests revealed that the solid-coated gloves were preferred by workers, but that the polyvinyl melted when working with hot drill steels.

Jan 1, 1985

By N. A. Gokcen

Equilibrium partial pressures of gaseous HCl and H2O over aqueous binary and ternary solutions of HCl and AICls were calculated or estimated in the range of 20° to 110° C, and up to saturation with AlC13?6H2O. The results were extended to solutions containing less than 10 wt-pct FeCl3 by assuming that FeCl3 and AIC13 are equivalent on the molar basis, since both salts have trivalent cations with a cammon anion. The ionic activity coefficient of HCl and the equilibrium constant for dissolution of gaseous HCl were also computed. This research is part of the effort by the Bureau of Mines, U.S. Department of the Interior, to provide thermodynamic data to expand the technology base relevant to the extraction of alumina from nonbauxitic domestic raw materials.

Jan 1, 1980